Assessment of the quality of reporting observational studies in periodontal literature

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Content

Assessment of the Quality of Reporting Observational Studies in Periodontal
Literature

Diane Costandi

A Thesis Presentation to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
(CRANIOFACIAL BIOLOGY)
August 2015

Copyright 2015 Diane Costandi

2

Table of Contents

Introduction Pages 3-10

Methods Pages 11-17

Results Pages 18-23

Discussion Pages 23-30

Conclusion Pages 30-31

Acknowledgement Page 31

List of References Pages 32-52

Figures Pages 53-87

3

Introduction:
Evidence-based dentistry is defined as “an approach to oral health-care decision-making
that requires the judicious integration of systematic assessments of clinically relevant
scientific evidence relating to the patient’s oral and medical condition and history,
together with the dentist’s clinical expertise and the patient’s treatment needs and
preferences” (Kwok et al., 2012). Such treatment decision-making involves scientific
evidence, experience and judgment of the clinician, patient preferences, and the clinical
circumstances of the patient (Kwok et al., 2012). Clinicians are using published dental
literature to support treatment decisions and explain dental processes to patients on a day-
to-day basis. With the use of current literature, dentists are able to familiarize themselves
with contemporary treatment options and the pros and cons of available technologies, and
to rationalize the use of a specific modality to treat patients. Thus, the information
presented in the dental literature becomes an important aspect of patient management and
must be critically analyzed to ensure appropriate interpretation and application.

Various study designs have been created with the lowest evidence being available in vitro
research and the highest evidence produced by meta-analyses and systematic reviews

(Kwok et al., 2012) (Fig. 1).Rrandomized controlled clinical trials are considered to be
superior in the hierarchy of evidence because that study design can potentially limit bias.
However, such trials may not be possible to use or implement because of the complexity
of setting up such trials or the limitation of such design and, thus, other research
methodologies are considered. Understanding study designs is important in evidence-
based dentistry, as it will aid in determining which information can be incorporated into

4

clinical practice and patient care.

One field of dentistry that is exponentially expanding with regards to research is
Periodontology. Several articles are published yearly addressing all aspects of
periodontology with attempts to improve clinical management of periodontal and implant
therapies. As a result, several advances have been made within the last 40-50 years

(Preshaw, 2012),

creating a wealth of research data that can be implemented in
periodontal practice.

Within the field of periodontology, epidemiological studies are important, as they attempt
to determine the prevalence of, incidence of

(Beck and Loe, 1993), and reason for disease
in different groups of people. With such information, clinicians are able to develop and
evaluate therapies to improve or prevent such disease. Epidemiological studies are further
classified into experimental or observational studies. Experimental studies, which are
considered the highest level of a clinical study design, include a treatment modality
aimed at changing disease exposure of progression (Kwok et al., 2012). Observational
studies, on the other hand, do not include any form of intervention and, instead, measure
and collect data to determine the distribution of specific variables within a population,
characterizing any associations between these variables and disease.

Observational studies can be further classified into two main subgroups: analytical or
descriptive studies (Fig. 2). Descriptive studies discuss the history, frequency, possible
modifiers, and characteristics of a specific condition, creating hypotheses about disease

5

causation. Case series and case reports, considered to be the lowest level of evidence

(Kwok et al., 2012), are defined as descriptive studies

(Grimes and Schulz, 2002). Case
series and case reports present descriptive data on selected subjects before and after a
specified treatment without a separate control group. More specifically, a case series
describes “clinical, pathophysiological, or operational aspect[s]” associated with a certain
disease or outcome in subjects with common characteristics

(Meijer and Raghoebar,
2012). Such studies are not ideal for guiding clinical decisions as they do not allow for
associations to be drawn

(Grimes and Schulz, 2002), but may provide an environment to
collect initial evidence for future, more elaborate studies.

Unlike descriptive studies, analytical studies include some form of a comparison group

(Grimes and Schulz, 2002). They are further sub-classified into cohort studies, which
provide the strongest level of evidence, case-control studies, and cross-sectional studies

(Preshaw, 2012)

(Fig. 2). These three study designs may relate health information
regarding types of disease, remission of disease, complications of disease, and occurrence
of risk factors of disease

(Vandenbroucke et al., 2007).

Cohort studies follow a group of subjects longitudinally to observe the effects of
exposure to various risk factors or treatment options. The subjects chosen for this study
(“the cohort”) are assembled in advance and their outcomes are observed at various
follow-up appointments. In general, a cohort study design can aid in identifying true risk
factors or incidence of disease, the number of new cases of a disease occurring over time

(Hulley et al., 2007). There are two main types of cohort studies: prospective and

6

retrospective. In a prospective cohort study, the investigator will select a sample,
measuring various characteristics that may affect the studied outcome, and follow-up the
cohort over time. This design strengthens inferences about associations between the
disease and selected variables, as there is no knowledge of the outcome as in
retrospective studies. In a retrospective cohort study, the cohort has been chosen in the
past along with the baseline and follow-up measurements. Because indirect sources are
used in the retrospective design, there is limited control over baseline measurements,
existing data, and follow-up

(Hulley et al., 2007).

Case-control studies reverse their sequence of measurements, with the investigator
working backwards; they are retrospective in nature

(Beck and Loe, 1993). Subjects with
the disease or outcome (the cases) are compared to other subjects without the disease or
outcome (the controls) to determine which variables, risk factors, or predictors are
associated with the effect of interest. Case-controls can yield a great amount of
information with a small number of subjects, especially in cases of rare diseases

(Grimes
and Schulz, 2002), and estimate the strength of an association between a disease and
variables

(Newman et al., 2007). However, with this study design, only a single variable
can be studied at a time and inferences about incidence or prevalence of the disease
cannot be made as the amount of individuals with the disease is determined by the
number of cases and controls selected for the study and not the actual proportion within a
given population

(Newman et al., 2007). With case controls, it is important to note that
improper selection of controls

(Grimes and Schulz, 2002) can lead to skewed results and
inaccurate conclusions.

7

Cross-sectional studies look at representative subjects at a specific time point to
determine the prevalence of disease within a population and the characteristics of
individuals with the disease, in aims to provide a hypothesis that can test for the
etiological factors responsible for the studied disease. Such study design aids in
monitoring disease trends, the effectiveness of specific treatments

(Beck and Loe, 1993).
A major advantage of this study design is the lack of loss to follow-up because all
measurements are made at a single time point. However, because cross-sectional studies
provide information about the proportion of individuals who have the disease at a specific
time point, casual relationships and definite conclusions about causes and prognosis may
be difficult to establish

(Hulley et al., 2007).

A large number of observational studies have been published regarding dental research
since they cost less, have quicker completion time, do not require randomization of
providers and/or patients

(Butani et al., 2006), and their ability to broaden their
population base

(Kwok et al., 2012). Despite these advantages, observational studies
present with an overall limitation of introducing bias into a study because of their non-
randomization and subject selection

(Butani et al., 2006). It is, thus, of importance that
the quality of published observational studies be analyzed to ensure the best quality of
patient care and the greatest positive impact on clinical practice.

Because observational studies constitute the majority of published dental research, it is
important that standards for conducting and reporting such research are present

(Butani et
al., 2006). Understanding any imprecision of uncertainty of published research data is

8

integral to clinical practice as it will drive which treatment options can be offered to
patients and their potential associated risks and benefits

(Needleman, 2005).

Because of the importance and role of observational literature in dental interventions, it is
critical that the reporting of these studies be strong and of good quality. To aid in such
efforts, a checklists has been introduced to guide authors on how to report on and to
improve the quality of reporting of observational studies. This statement, created by
several medical researchers, methodologists, epidemiologists, and statisticians

(Von Elm
et al., 2008), is referred to as “Strengthening the Reporting of Observational Studies in
Epidemiology (STROBE)”. The initiative started in 2004, when the scope of STROBE
was established to include three specific study designs of observational studies: cohort,
case-control, and cross-sectional studies. The STROBE checklist consists of 22 items
(Table 1) relating to the title, abstract, introduction, methods, and discussion sections of
articles that are considered essential on reporting of observational research. A checklist
for each of the three types of studies and a combined checklist including cohort, case-
control, and cross-sectional studies have been created for the following purposes: “to
assist authors when writing up analytical observational studies, to support editors and
reviewers when considering such articles for publication, and to help readers when
critically appraising published articles” (Von Elm et al., 2008).

In essence, the STROBE
statement exists to assess the quality of reporting and not the quality of the research

(Vandenbroucke et al., 2007).
In Europe, a study

(Mannocci et al., 2014) was conducted to look at the impact of
reporting guidelines (including STROBE) for various study types in public health

9

literature published between 2010 and 2013. Of the 3,456 articles reviewed, 2,117 were
classified as observational studies and followed the guidelines for STROBE 0-0.6% of
the time

(Mannocci et al., 2014).

In an article published in 2006, Butani et al. evaluated the reporting quality of
observational studies published in pediatric dental literature. They concluded that
different observational studies comparing the same treatment modalities could present
with substantially different results. Therefore, the authors expressed that observational
studies should be guided in their data collection and analysis and the reporting of their
results (Butani et al., 2006).

In 2011, Pandis and colleagues

(Pandis et al., 2011) looked at the top impact journal in all
specialties of dentistry: Endodontics, Oral and Maxillofacial Surgery, Orthodontics,
Pediatric Dentsitry, Periodontology, and Prosthodontics. They wanted to analyze the
quality of published research, including various study designs, across the selected 6
specialty journals. Of 396 articles examined in the study, cross-sectional studies
constituted the majority of published data overall (55%), while interventional and
observational studies were mostly found within the periodontal literature. When assessing
the various variables (random allocation, sample size calculation, confounding issues,
effect measurement, and multivariate analysis) affecting the overall quality of the
research studied, all variables scored below 40%. Of all the journals analyzed, the
Journal of Clinical Periodontology was found to include more of the characteristics that
define quality research

(Pandis et al., 2011).

10

More recently, Meijer and Raghoebar assessed the quality of observational studies
published on implant dentistry using the aforementioned STROBE statement. Of the 260
articles included in this study, the authors reported an improvement from 1990 to 2010 in
the percentage of items that were properly addressed in the STROBE checklist. The
highest reported average percentage was 84% given in 2010 for the introduction section
of the selected articles, but no more than 70% was given for a full article
149
. Medical
literature too, has stated that the quality of published observational studies was
“insufficient” (Meijer and Raghoebar, 2012).

Given that observational studies compromise most of published dental literature

(Butani
et al., 2006), constituting nine out of ten articles published in “specialty journals,”

(Pandis
et al, 2011) and are important in the expanding field of periodontology, it is important to
measure the standards of reporting of these studies. One journal commonly referred to in
the field of Periodontology, with over 200 articles produced in 2013 is the Journal of
Periodontology. Thus, this study aims to assess the quality of reporting on observational
studies published in the Journal of Periodontology in 2013 using the STROBE checklist.
The null hypothesis was that the reporting quality of published observational studies in
the Journal of Periodontology is good (above 85%).

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Methods:
Inclusion and Exclusion Criteria:
Because this study was based on literature review, IRB approval was not required.

Being the official publication of the American Academy of Periodontology and because
of its large influence on the field, the Journal of Periodontology was assessed in this
study. Articles published from January 1, 2013 until December 31, 2013 were included in
this study as they culminated the work of the most current full year from which this study
was created and the data was collected. Also, selecting articles from 2013 allowed a good
number of years (>5 years) for the STROBE checklist to be put into use by various
researchers and reviewers, since its release in 2007.

The types of observational studies included in this quality assessment were the analytical
ones - cohort studies, retrospective and prospective in nature, case-control studies, and
cross-sectional studies. Since these three observational study types are considered to
provide the highest level of evidence in the hierarchy of observational research, they were
the ones choses for analysis. The inclusion of the studies was not restricted to certain
topics or treatments, but all reports considered to be analytical observational studies, as
defined above.

Case series, case reports, in vitro studies, animal studies, experimental studies,
interventional studies, randomized controlled clinical trials, systematic reviews, and
meta-analyses were excluded in this research. Any retrospective or prospective cohort,

12

case-control, or cross-sectional studies conducted on initial data collected from animal
studies, experimental studies, interventional studies, or randomized controlled clinical
trials were also excluded in this assessment.

Search Strategy
An initial hand search of the literature was conducted in the 13 published issues of the
Journal of Periodontology from the year 2013. This was supplemented by an electronic
search restricted to volume 85 of 2013 on the journal’s website
(http://www.joponline.org) to ensure that all the electronic articles were not missed in the
hand search.

During the screening, all addresses, obituaries, editorials, letters, commentaries, peer
reviews, corrigendum, erratum, and meeting abstracts were excluded from the study.
Titles were initially screened followed by the abstracts to exclude any articles that did not
match the inclusion criteria. The remaining articles were then read all the way through to
determine if they were cohort, case-control, or cross-sectional studies and fit the inclusion
criteria defined above (Fig. 3).

One examiner (first authors) independently assessed the Journal of Periodontology
regarding eligible studies. When the eligibility of a study was questionable, a second
reviewer was asked. If an agreement regarding the eligibility of a selected study could not
be reached, a third reviewer was asked to evaluate the article and a decision was reached.

13

Data Extraction
The published “Strengthening the Reporting of Observational Studies in Epidemiology
(STROBE)” statement was used to assess the quality of observational studies. The
combined checklist from 2007 for cohort, case-control, and cross-sectional studies was
used to assess 22 various criteria relating to the title, introduction, methodology, results,
discussion, and other additional information. The studies included in this review were
analyzed against the 22 criterions in the following manner: a Yes indicates that a study
has met the indicated criterions, while a No indicates that a study has not met the
indicated criterions. For those sections that included more than one criterion (items 1, 6,
12, 13, 14, and 16), each of these sub-criterions was separately scored with a yes or a no.
Again, a Yes indicates that a study has met the indicated criterions, while a No indicates
that a study has not. All the criteria that received a Yes were given a numerical score of 1,
while all those criteria that received a No were given a 0. If a specific item of the
STROBE checklist was not applicable to a given study, that study received an NA and no
numerical score.

For the exact definition and explanation of each of the 22 items used in the STROBE
checklist and to determine if they were appropriately reported, the guidelines explained in
the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE)
Explanation and Elaboration (Vandenbroucke et al, 2007) were used. For item 1a, an
explicit and commonly used term should be indicated to define the study type in the title
or abstract. The terms observational, cross-sectional, case-control, or cohort were
accepted in this study and given a Yes and a score of 1. For item 1b, key items and details

14

should be summarized in the abstract to give a concise overview of the article.
For item 2, the scientific background should give an overview of the topic and lacking
knowledge that may be present.
For item 3, the aims of the study should be detailed and stated.
For item 4, key elements of the study design should be indicated at the end of the
introduction or in the methods section. More specifically, “authors should indicate that
the study was a cohort study, which followed people over a particular time period, and
describe the group of persons that comprised the cohort and their exposure status.
Similarly, if the investigation used a case-control design, the cases and controls and their
source population should be described. If the study was a cross- sectional survey, the
population and the point in time at which the cross-section was taken should be
mentioned” (Vandenbroucke et al, 2007).
For item 5, the location and setting of the study needs to be clearly defined.
For item 6a, the description of the study participants must be clearly stated. For item 6b,
the matching of subjects within a cohort or case-control study must be explained.
For item 7, all the variables considered in the study must be evident and outlined.
For item 8, the way by which each variable was measured must be explained.
For item 9, bias must be indicated and assessed by the authors of the individual articles.
For the purpose of this study, any article in which the word bias was not used was given
an automatic No and 0 for this category.

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For item 10, the determination of the sample size must be indicated. For those studies that
indicated they were unable to calculate a sample size because of insufficient data
available were given a Yes and a score of 1 for this criterion.
For item 11, authors must describe how quantitative data was grouped and analyzed.
For item 12a, the type of statistical analysis for the various data points should be
indicated. In this study, if the type of statistical study was indicated in a table with the
data and/or in writing within the article that study was given a Yes and a score of 1 for
this criterion. For item 12b, the indication and type of analyses completed for subgroups
must be mentioned. For item 12c, the article must explain the how missing data factored
into the overall analysis. For item 12d, the amount of individuals lost during the study
must be indicated. More specifically, for cross-sectional studies, the analytical methods
used to adjust for complex sampling strategies should be discussed. In this analysis, those
cross-sectional studies that did not explicitly indicate their sampling strategy, were given
a No and a score of 0 for this criterion. For item 12e, the study must conduct a sensitivity
analysis to investigate the consistency of results.
For item 13a, the details of subject recruitment should be included in the study. For item
13b, an explanation of why subjects were excluded or dropped out from a study should be
expressed. For item 13c, a flow diagram is recommended, especially for complex studies.
In this study, any article that did not present with a flow diagram was given a No and a
score of 0 for this criterion.
For item 14a, detailed descriptions of the study participants should be given. In this
study, only those articles that presented a separate table of the subject characteristics was

16

given a Yes and a score of 1 for this criterion. For item 14b, the number of missing data
for each selected variable should be clearly indicated. For item 14c, cohort studies must
present the average or overall duration of the study.
For item 15, descriptive data should be presented indicating the rate of an occurrence or
outcome of an event.
For item 16a, unadjusted must be presented with or without data adjusted for different
variables or confounders. For item 16b, data should be presented with boundaries such as
range of values or specific decimal places. For item 16c, an absolute risk for relevant
studies should be considered. In this analysis, those studies that reported an odds ratio
were given a No and a score of 0 for this criterion. Only those studies that indicated a
dependent association of their data were considered for this criterion in this analysis.
For item 17, if any other types of analyses, such as subgroup analyses, were conducted
within the study, they must be identified.
For item 18, a summary of the overall findings of the paper should be presented.
For item 19, the limitations and biases of the study should be pinpointed and explained.
In this study, if either the limitation or the bias was not discussed, the article received a
No and a score of 0 for this section.
For item 20, the overall interpretation of the results of the study, including limitations,
should be indicated. In this analysis, if an article failed to express any limitations, it was
given a No and a score of 0 for this criterion.

17

For item 21, the external validity of the specific study should be explained. In this
assessment, if the article did not clearly state how such data affects or impacts clinicians,
it was given a No and a score of 0 for this criterion.
Finally, for item 22, the conflict of interest along with the source of funding and the role
of funders should be indicated in detail. In this analysis, an article was given a No or a
score of 0 if it did not clearly indicate what part of the study each of the funders was
responsible for. In this study, if criteria 5-22 were explained anywhere within the article
and not necessarily within the specified Methods, Results, or Discussion sections of the
article.
The same examiner independently analyzed the eligible studies against the 22 criteria of
the STROBE statement. All items were scored and recorded for each article. When
eligibility of a selected study could not be determines, a discussion was held between the
first and second examiners till a consensus was reached.

Statistical Analysis
Descriptive statistics were used to present data of STROBE compliance in terms of
percentages of properly addressed items per section. More specifically, the percentage of
appropriately addressed criteria in the STROBE checklist was calculated for each
selected article. Alongside this, the mean percentages for properly addressing each of the
22 items on the checklist and the overall average of STROBE guidelines addressed by all
the articles selected in this analysis were calculated.

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Results:
Study Characteristics
The electronic and hand search of the Journal of Periodontology from January 1, 2013 to
December 31, 2013 identified a total of 245 articles. From assessing the titles, 151
articles were excluded. The resulting 94 abstracts were obtained and screened, and 22
were excluded. Full-text articles were obtained for the 72 remaining articles, and after
reading through the entirety of the text, 13 of the articles were further excluded.

Reviewer agreement
Slight disagreements, which occurred for a couple of articles, were generally caused by
minor differences in the interpretation of the studies, but were easily resolved by
consensus discussion with a 2
nd
reviewer or by a third reviewer. Only two articles
137, 175

required a third reviewer during the full read of the articles resulting in the exclusion of
one article
175
for being descriptive and the inclusion of the other
137
as a cross-sectional
study.

Exclusion of studies
The 186 excluded studies along with their reason for exclusion are presented in Table 2.
Of these articles, four were letters to the editor, two were obituaries, one was a
corrigendum, three were erratums or classifications, three were addresses by the
academy, two were workshop-related, three were research abstracts, three were peer
reviews, two were commentaries, three were consensus reports, seven were literature
reviews, twelve were systematic reviews, twenty-seven were animal studies, forty-five

19

were in vitro studies, one was an interventional study, two were controlled clinical trials,
fifteen were experimental studies, three were meta-analyses, one was a randomized case
presentation, thirty were randomized clinical trials, two were quality assessments, 6 were
descriptive studies, three were case series, one was a cohort study considering data from
case series, four were cohort studies that considered data from clinical trials (randomized
controlled clinical trials, included), and one was a case control considering in vitro data.

The reasons for excluding the 13 articles after full reads were: cohort study based on a
clinical trial (n=4), cohort study based on data from case series (n=1), case-control study
with an in vitro component (n=1), case series (n=1), descriptive study (n=4),
experimental study (n=2).

Inclusion of studies
The 59 studies included in this assessment along with their reason for inclusion are
presented in Table 3. Eleven of these studies were cohort studies (18.64%), with 6 of
them being prospective in nature (54.55%) and 5 retrospective in nature (45.45%),
eighteen were case-control studies (30.51%), and 30 were cross-sectional studies
(50.85%) (Figure 4).

STROBE checklist analysis
The 59 studies that met the inclusion criteria and thus, included in this analysis, were
scored for each of the 22 items of the STROBE checklist (Table 1).

20

When assessing the average compliance of each section of all the included articles (Title
and Abstract, Introduction, Methods, Results, Discussion, and Other) to the STROBE
checklist items, the highest percentage of compliance was found in the Introduction
section (97.46%), followed by the Results section (74.24%), the Methods section
(70.81%), the Discussion section (68.64%), the Title and Abstract sections (33.90%), and
the Other section, which resulted in the lowest compliance at 15.25% (Figure 5).

Title, Abstract, and Introduction sections
When taking a closer look at the exact STROBE items in each section, it was found that
the highest percentage compliance of all the analyzed articles in the Title, Abstract, and
Introduction sections was to STOBE item 2 with a 100% average compliance and the
lowest to STROBE item 1 with a 33.90% average compliance (Figure 6). More
specifically, subcategories of STROBE item 1 resulted in a 100% average compliance to
STROBE item 1b and a 33.90% to STROBE item 1a (Figure 7). Within all the included
59 articles, approximately 46% (27 articles) mentioned their study design, while the
remaining 54% (32 articles) did not (Figure 8). Of those articles that did mention the type
of observational study they were, 74% indicated in the Title or Abstract, 15% in the
Methods section, and 4% in the Introduction, Discussion, and Conclusion sections
(Figure 9).

Methods section
In the Methods section, STROBE items 4 to 12 are included. When assessing the average
compliance to these STROBE items in the Methods section, the highest average

21

compliance of 100% was found with items 5, 6, and 8, while the lowest average
compliance of 5.08% was found with item 12. There was a 98.31% compliance to item
11, 94.92% to item 7, 89.83% to item 4, 25.42% to item 10, and a 23.73% compliance to
item 9 (Figure 10). When taking a closer look at STROBE items 6 and 12, they present
with subcategories. With regards to item 6, there was a 100% compliance to item 6a and
item 6b (Figure 11). With item 12, there was a 100% compliance to items 12a and 12b,
an 85.71% compliance to item 12c, a 54.35% compliance to item 12d, and a 6.78%
compliance to item 12e (Figure 12).

Results section
The Results section of the analyzed articles coincides with STROBE items 13 to 17. In
assessing the average compliance of the selected articles with these specific STROBE
items, the highest average percentage compliance was to items 15 and 17 at 100%, while
the lowest compliance was found with item 13 at 6.78%. There was an average
compliance of 86.44% to item 16 and a 77.97% average compliance to item 14 (Figure
13). STROBE items 13, 14, and 16 present with subcategories. With regards to STROBE
item 13, there was a 100% average compliance to items 13a and 13b, but only a 6.90%
average compliance to item 13c (Figure 14). With STROBE item 14, there was a 91.67%
compliance to item 14c, an 81.36% compliance to item 14a, and a 78.57% compliance to
item 14b (Figure 15). With STROBE item 16, there was a 100% compliance to item 16b,
a 98.31% compliance to 16a, and a 22.22% compliance to item 16c (Figure 16).

22

Discussion and Other sections
The Discussion and Other sections of the articles selected for this analysis coincide with
items 18 to 22 on the STROBE checklist. When determining the average percentage of
compliance to these specific STROBE items, the highest percentage of compliance was
to item 18 at 100%, followed by items 20 and 21 at 77.97%, item 19 at 18.64%, and item
22 with the lowest average percentage of compliance at 15.25% (Figure 17).

Overall, the highest average compliance of 100% was found with STROBE items 2, 5, 6,
8, 15, 17, and 18, while the lowest average compliance of 5.08% was found with
STROBE item 12. The average compliance to the other STROBE items is as follows:
item 11 (98.31%), items 3 and 7 (94.92%), item 4 (89.83%), item 16 (86.44%), items 14,
20, and 21 (77.97%), item 1 (33.90%), item 10 (25.42%), item 9 (23.73%), item 19
(18.64%), item 22 (15.25%), and item 13 (6.78%) (Figure 18). In essence, mentioning of
the background/rationale, setting, participant description, data measurements, outcome
data, and the key results of the study were very well addressed, achieving an average
100% compliance by all included studies. Bias, study size, statistical methods, participant
results, limitations, and funding of the study were all areas that were poorly addressed,
achieving an average compliance of less than 30% by all included studies.

An average compliance of each of the included 59 articles against the 22 items of the
STROBE checklist was calculated. Only 1 paper scored an average compliance between
90-99% to the STROBE checklist, while 7 scored between 80-89%, 14 scored between
70-79%, 29 scored between 60-69%, and 8 scored an average compliance to the

23

STROBE checklist between 50-59% (Figure 19). Of the analyzed 59 articles, 25% of the
articles had an average compliance between 75-100%, while 75% of the articles had an
average compliance between 50-74% (Figure 20). Furthermore, only 2% of the included
59 articles scored an average compliance percentage between 85-100%, while 98% of
those articles scored and average compliance percentage between 50-84% (Figure 21).

Discussion:
In this study, the quality of observational studies (case-control, cross-sectional, and
cohort) published in the Journal of Periodontology in the year 2013 were assessed using
the STROBE statement. For the included 59 studies, the percentage of properly
addressing the 22 items of the checklist was calculated to determine the quality of
reporting. The results illustrate that 98% of the analyzed articles complied between 50%
to 84% of the STROBE checklist, while only 2% of the analyzed articles complied to
between 85% to 100% of the STROBE checklist items.

It is not surprising to find that the least commonly published observational studies are the
cohort type (18%), both prospective and retrospective, (Figure 4) as cross-sectional and
case-control studies are less time consuming and require less finances to conduct

(Silva,
1999). With regards to cross-sectional and case-control studies, cross-sectional studies
do not require follow-up or a strict selection of a control group (Berker, 2013) and are
thus easier to conduct, measuring a sample population at a single time point. In an article
published in 2012 assessing risk factors affecting implant dentistry using the STROBE
statement, the authors expressed that very few cohort studies exist within the literature

24

because of the complexity of the study design, especially when “the incidence of the
outcome assessed is rare” (Berker, 2013).

The quality of reporting differed per article section as can be seen in Figure 5. The
Introduction section scored the best (above 95%), while the “Other” section scored the
lowest (less than 20%). It is not striking that the STROBE items of the Introduction
section were well addressed as they focus on the background, rationale, and objectives of
the study.

Although several of the studies indicated that they received funding or which grant was
associated with their research, only 15% actually gave the role of the funders in the study
and what particular portion of the research they contributed to. As indicated in the
instructions to authors who wish to publish in the Journal of Periodontology, a statement
must be created indicating the source of funding for the study and defining any
commercial relationships of each of the authors, alluding to any conflict of interests. In
some instances, no sources of external funding may have been used in a particular study
and solely the resources of the researcher’s department(s) or university department(s). In
such cases, authors may not find it necessary to indicate where it is they received their
funding since it was all internally based. Although this may occur, it is imperative that
authors specifically indicate where they received funding for their research to prevent any
misunderstandings. A systematic review published in JADA in 2013

(Bekelman, 2003)
illustrated that financial conflicts of interest can influence the results of published
research, ultimately affecting its application in clinical practice.

25

When specifically looking at the STROBE items of the Title and Abstract, it is interesting
to note that about 54% of the included articles failed to indicate their study design within
the Title or Abstract of the article (Figure 8). However, if looking at the mention of the
study design within the entirety of the article, the number on articles was reduced to 46%.
Of the articles that indicated their study design, the majority (74%) indicated within the
Title and Abstract, while others indicated in the Methods, Results, Discussion, and
Conclusion sections. Most of the articles that cited the study design in the discussion or
conclusion section mentioned it as a discussion of a limitation or strength of the research.
It is important that authors indicate the type of study so that readers can better and more
easily understand the validity and extraction of the research results obtained. It is
important to note, however, that some research may incorrectly indicate their type of
study as a result of their design and setup, and thus readers must be familiar with the
various study designs available and critically analyze all research that is read.

When looking at STROBE items 4-12 of the Methods section, it is interesting to note that
the average compliance to items 9, 10, and 12 were less than 30%, with item 12 having
an average compliance of less than 6% (Figure 10). Item 9 refers to the efforts made by
the authors to indicate and explain and sources of bias. One of the major disadvantages of
observational studies is to attempt to prevent and to discover any areas of bias that may
affect the research outcome and the reliability of the data

(Needleman et al., 2005). Given
its importance in such studies, it is surprising that only 24% of articles actually addressed
the source of bias within their studies. Bias is defined as “a collective term for factors that
systematically distort the results of research away from the truth” (Beck and Loe, 1993).

26

Different types of bias can exist

(Sanderson et al., 2007) including subject selection,
performance, and measurement, which can ultimately skew the reported results

(Sackett,
1979). Thus, it is important that more focus is directed towards assessment of bias with
each research project.

With regards to STROBE item 10, only 25% of the analyzed articles expressed how it is
the sample size was arrived at (Figure 10). Sample size determination is important
because it can affect the statistical precision of the results. It is important to understand,
however, that with observational studies, authors may be unaware of the number of
individuals who will actually meet their criteria selection and thus, provide no power
calculation. At times, the a sample size may not be determined beforehand because of the
imprecision of measuring variables, inability to define clinically important differences, or
the possibility of having to reduce confounding factors.

In looking at STROBE item 12 of the Methods section, 54.35% of the articles discussed
loss to follow-up in cohort studies, matching of cases and controls in case-control studies,
and sampling strategy in cross-sectional studies (item 12d), while only 6.78% of the
articles described any sensitivity analyses (item 12e) (Figure 12). Missing data commonly
occurs in observational studies, and unfortunately, is not fully reported, which may
ultimately affect the overall results and analyses of a single study

(Tooth et al., 2005).
With matched case-controls, the authors should indicate the analysis used to ensure that
no bias in introduced into the study (Von Elm et al., 2008). With the cross-sectional
studies, understanding their sampling strategy is important, especially when estimates of

27

association want to be made. Because the sampling strategy can affect the precision of
results, it is important that authors clearly state the methods they use so that readers can
understand and appropriately determine the results presented (Von Elm et al., 2008).
Sensitivity analysis is useful in investigating whether the main results obtained within the
study are comparable or similar to those that would be obtained with different variables
or assumptions. Such analyses can help identify to what degree an association,
confounding factors, or bias is present within a study, all of which ultimately affect the
main results and their applicability (Von Elm et al., 2008).

In analyzing the Results section, STROBE items 13-17 are assessed, with item 13 having
only a 6.78% average compliance from all the included studies and item 14 having a
77.97% average compliance (Figure 13). When looking at the subcategories for item 13,
there is a poor compliance at 6.90% to item 13c, the presence of a flow diagram (Figure
14). A well-structured flow diagram is useful in observational studies, which may
become confusing participants lost as a result exclusion criteria or lost to follow-up. Such
charts can aid in vividly and readily conveying important information regarding the study
that would otherwise need to be understood through reading a lengthy description within
the article

(Egger et al., 2001). As a result, it is imperative that authors consider placing
such diagrams to help readers better understand the flow of the reported study. When
looking at the subcategories for item 14, there is a compliance of 81.36% to 14a and a
78.57% of compliance to item 14b (Figure 15). Item 14a refers to the characteristics of
the study participants. In this analysis, only those articles that included a separate table
for patient characteristics were indicated as complying with this specific criterion in

28

hopes of minimizing subjectivity. This stringent definition may have resulted in an
underreporting of the compliance rate of studies, which do indicate patient characteristics
in the methods section, but not in a separate table format. Item 14b refers to the indication
of the number of participants with missing data for various variables. As iterated above, it
is important to indicate the amount/number of missing variables as such information will
affect the statistical analysis of the study and overall, the results, conclusion, and their
validity.

When looking at the STROBE checklist, items 18 to 21 coincide with the Discussion
section of an analyzed article (Figure 17). Of these criterions, item 19 had an average
compliance of less than 20%, while items 20 and 21 had an average compliance of
approximately 78%. Item 19 refers to the discussion of the limitations of the study along
with reporting on sources of bias. Because STROBE item 9 included efforts to report
bias, all those studies that failed to comply with item 9 also failed to comply to item 19.
Only 3 articles (27.27%) that did not comply with item 19 were due to failure to indicate
limitations of the study, while the rest of the articles failed to indicate any source of bias.
Such results further allude to the importance of reporting bias within a given study.
Reporting and discussing the limitations of a particular study can affect the
generalizabilty, validity, and the precision of the results and conclusions reported within
the paper

(Von Elm et al., 2008). Item 20 also included the interpretation of limitations of
a study and thus, all those studies that failed to comply with item 19, with regards to
study limitations, also failed to comply with this item as well. Finally, item 21 referred to
the external validity of the study results. Of the analyzed studies, 77.97% actually

29

indicated the applicability, or “the extent to which the results of a study can be applied to
other circumstances” (Von Elm et al., 2008). It is important for readers to know to what
extent the results of a particular study can be applied as such information can potentially
affect their treatment decisions.

When taking an overall look at the average compliance of the selected articles to the
STROBE checklist, most studies addressed the background/rationale, setting, participant
description, data measurements, outcome data, and the key results of the study very well
(100% compliance). Areas that require vast improvement are bias, study size
determination, statistical methodology, participant results, limitations, and funding of the
study, achieving an average compliance of less than 30% (Figure 18). Such results are
similar to the results of Rochietta et al., which found the statistical methods, particularly
reporting on how missing data was handled and sensitivity analyses, to be the weakest
points of all their analyzed articles (Rocchietta and Nisand, 2012). In another study on the
reporting of observational studies in dermatology journals by Langan et al, only 9% of
the included articles explained the role of the funders, similar to our reported 15% in this
analysis (Langan et al., 2010). In another assessment of the quality of reporting
surrounding peri-implant disease, Tomasi and Derks

reported that one of the “most
obvious shortcomings” was the indication of the study design within the title or abstract,
which occurred in 25% of their studies; such results are similar to our observed 33.90%
of studies (Tomasi and Derks, 2012). Another area that required improvement according
to Tomasi and Derks was the indication and assessment of bias within published research
(Tomasi and Derks, 2012).

30

When we analyze all the included papers and their average compliance to the STROBE
checklist, we observe that the majority of the papers (about 59%) scored between 60-69%
(Figure 19). More specifically, only 25% of the papers had a compliance rate between 75-
100% (Figure 20), while only 2% (1 paper of the 59 analyzed) scored a compliance rate
between 85-100% (Figure 21). A study analyzing the impact of the STROBE statement in
dermatology journals between 2004 and 2010, found the median score of studies
complying to the STROBE statement to be about 57%, with an improvement of this
number by about 10% between 2004-2005 and 2008-2010 (Batsuji-Garin et al., 2013).

In conclusion, this analysis has helped highlight critical item of the STORBE checklist
that are not appropriately addressed within observational studies, suggesting room for
improvement in reporting. Addressing such items for future studies will not only improve
the quality of reporting research, but provide readers and clinicians with more reliable
means of analyzing research data and applying such knowledge to their every-day
practice. It appears that observational studies published in periodontal literature,
including the Journal of Periodontology, would benefit from the incorporation and usage
of the STROBE statement in reporting their research.

Conclusion:
It is important to reiterate that a vast amount of clinical knowledge comes from
observational research that can provide information ranging from disease transmission to
the detection of treatment effects and treatment outcomes. Such information is valuable
to the field of periodontology, where clinicians use the results and evidence of published

31

research to decide treatment modalities for patients in every day practice. From our
analysis in this project, it can be concluded that the overall quality of reporting of
observational studies published in the Journal of Periodontology in 2013 was below 85%
with majority of the papers (about 59%) scored between 60-69%, while only 2% (1 paper
of the 59 analyzed) scored a compliance rate between 85-100%. Editors, reviewers and
authors should be further encouraged to adhere with STROBE statement to improve
quality of reporting in observational studies in Journal of Periodontology

Acknowledgement:
I would like to thank Dr. Satish Kumar for the conception of this study and his
mentorship and guidance regarding research writing and analysis. I would like to that Dr.
Sarah Bushehri for acting as the second examiner in the literature search associated with
this study and Dr. Satish Kumar for acting as a third reviewer in the literature inclusion of
this study. Finally, I would like to thank Dr. Kar, Dr. Paine, and Dr. Sameshima for their
mentorship, feedback, and support with this study and the associated manuscript.

32

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136. Li, C., Liu, J., Tan, L., Yu, N., Lin, L., Geng, F., Zhang, D., and Pan, Y.
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162. Morandini, A.C., Chaves Souza, P.P., Ramos-Junior, E.S., Brozoski, D.T.,
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R.L., and Buekens, P. (2013). Change of periodontal disease status during and
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263. Yu, N., Prodanov, L., te Riet, J., Yang, F., Walboomers, X.F., and Jansen,
J.A. (2013). Regulation of periodontal ligament cell behavior by cyclic
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52

264. Yuh, D.Y., Cheng, G.L., Chien, W.C., Chung, C.H., Lin, F.G., Shieh,
Y.S., Fang, W.H., Mau, L.P., Fu, E., and Huang, R.Y. (2013). Factors affecting
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(2013). The clinical effect of scaling and root planing and the concomitant
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Periodontol. 84(3), 332-51.
266. Zhang, S., Barros, S.P., Moretti, A.J., Yu, N., Zhou, J., Preisser, J.S.,
Niculescu, M.D., and Offenbacher, S. (2013). Epigenetic regulation of TNFA
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267. Zhao, L., Wu, Y., Tan, L., Xu, Z., Wang, J., Zhao, Z., Li, X., Li, Y., Yang,
P., and Tang, T. (2013). Coculture with endothelial cells enhances osteogenic
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and Duarte, P.M. (2013). Local and circulating levels of adipocytokines in obese
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624-33.

53

Figures
Figure 1. Hierarchy of Research Evidence

Figure 2. Classification of Observational Studies
Observational
Study
Analytical
Study
Cohort Study
Case-Control
Study
Cross-sectional
Study
Descriptive
Study
Case Report Case Series

54

Table 1. STROBE checklist of items to be included in reports of observational studies
(cohort, case-control, and cross-sectional) in epidemiology
Topic Item Recommendations
Title and abstract 1 (a) Indicate the study’s design with a commonly used term
in the title or the abstract
(b) Provide in the abstract an informative and balanced
summary of what was done and what was found
Introduction
Background/rationale 2 Explain the scientific background and rationale for the
investigation being reported
Objectives 3 State specific objectives, including any pre-specified
hypotheses
Methods
Study design 4 Present key elements of study design early in the paper
Setting 5 Describe the setting, locations, and relevant dates,
including periods of recruitment, exposure, follow-up, and
data collection
Participants 6 (a) Cohort study—Give the eligibility criteria, and the
sources and methods of selection of participants. Describe
methods of follow-up
Case-control study—Give the eligibility criteria, and the
sources and methods of case ascertainment and control
selection. Give the rationale for the choice of cases and
controls
Cross-sectional study—Give the eligibility criteria, and
the sources and methods of selection of participants
(b) Cohort study—For matched studies, give matching
criteria and number of exposed and unexposed
Case-control study—For matched studies, give matching
criteria and the number of controls per case
Variables 7 Clearly define all outcomes, exposures, predictors,
potential confounders, and effect modifiers. Give

55

diagnostic criteria, if applicable
Data sources/
measurement
8* For each variable of interest, give sources of data and
details of methods of assessment (measurement). Describe
comparability of assessment methods if there is more than
one group
Bias 9 Describe any efforts to address potential sources of bias
Study size 10 Explain how the study size was arrived at
Quantitative
variables
11 Explain how quantitative variables were handled in the
analyses. If applicable, describe which groupings were
chosen and why
Statistical methods 12 (a) Describe all statistical methods, including those used
to control for confounding
(b) Describe any methods used to examine subgroups and
interactions
(c) Explain how missing data were addressed
(d) Cohort study—If applicable, explain how loss to
follow-up was addressed
Case-control study—If applicable, explain how matching
of cases and controls was addressed
Cross-sectional study—If applicable, describe analytical
methods taking account of sampling strategy
(e) Describe any sensitivity analyses
Results
Participants 13* (a) Report numbers of individuals at each stage of study—
eg numbers potentially eligible, examined for eligibility,
confirmed eligible, included in the study, completing
follow-up, and analyzed
(b) Give reasons for non-participation at each stage
(c) Consider use of a flow diagram

56

Descriptive data 14* (a) Give characteristics of study participants (eg
demographic, clinical, social) and information on
exposures and potential confounders
(b) Indicate number of participants with missing data for
each variable of interest
(c) Cohort study—Summarize follow-up time (eg, average
and total amount)
Outcome data 15* Cohort study—Report numbers of outcome events or
summary measures over time
Case-control study—Report numbers in each exposure
category, or summary measures of exposure
Cross-sectional study—Report numbers of outcome events
or summary measures
Main results 16 (a) Give unadjusted estimates and, if applicable,
confounder-adjusted estimates and their precision (eg,
95% confidence interval). Make clear which confounders
were adjusted for and why they were included
(b) Report category boundaries when continuous variables
were categorized
(c) If relevant, consider translating estimates of relative
risk into absolute risk for a meaningful time period
Other analyses 17 Report other analyses done—eg analyses of subgroups
and interactions, and sensitivity analyses
Discussion
Key results 18 Summarize key results with reference to study objectives
Limitations 19 Discuss limitations of the study, taking into account
sources of potential bias or imprecision. Discuss both
direction and magnitude of any potential bias
Interpretation 20 Give a cautious overall interpretation of results
considering objectives, limitations, multiplicity of
analyses, results from similar studies, and other relevant
evidence

57

Generalizability 21 Discuss the generalizability (external validity) of the study
results
Other information
Funding 22 Give the source of funding and the role of the funders for
the present study and, if applicable, for the original study
on which the present article is based

* Give information separately for cases and controls in case-control studies and, if
applicable, for exposed and unexposed groups in cohort and cross-sectional studies.

58

Figure 3. Flowchart of the selected articles in the current analyses

59

Table 2. Excluded Studies with Reason for Exclusion
Title Reason for
Exclusion
Peer Review Panel and Ad Hoc Reviewers for the Journal of
Periodontology
Peer Review
Efficacy of Subgingivally Delivered Simvastatin in the Treatment of
Patients With Type 2 Diabetes and Chronic Periodontitis: A
Randomized Double-Masked Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Host–Bacterial Interactions During Induction and Resolution of
Experimental Gingivitis in Current Smokers
Experimental
Treatment of Localized Gingival Recessions Using Gingival Unit Grafts:
A Randomized Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Influence of Endodontic Treatment in the Post-Surgical Healing of
Human Class II Furcation Defects
Controlled
Clinical Trial
(Case Series)
Accuracy of Linear Measurements and Visibility of the Mandibular
Canal of Cone-Beam Computed Tomography Images With Different
Voxel Sizes: An In Vitro Study
In Vitro
Effect of a Collagen Membrane Combined With a Porous Titanium
Membrane on Exophytic New Bone Formation in a Rabbit Calvarial
Model
Animal
Nano-Sized Calcium Phosphate Particles for Periodontal Gene Therapy In Vitro
Human Neutrophil Defensins and Their Effect on Epithelial Cells In Vitro
Obituary: Robert S. Schoor, DDS Obituary
The Effect of an 810-nm Diode Laser on Postoperative Pain and Tissue
Response After Modified Widman Flap Surgery: A Pilot Study in
Humans
Experimental

60

Effect of the Timing of Restoration on Implant Marginal Bone Loss: A
Systematic Review
Systematic
Review
Quality Assessment of Systematic Reviews on Periodontal Regeneration
in Humans
Quality
Assessment
Toothbrushing Education via a Smart Software Visualization System Interventional
Immediate Implant Placement in Infected Sites: A Case Series Case Series
Efficacy of Varying Concentrations of Subgingivally Delivered
Metformin in the Treatment of Chronic Periodontitis: A Randomized
Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Guided Bone Regeneration Using Injectable Vascular Endothelial
Growth Factor Delivery Gel
Animal
A Novel Approach for Enhanced Nanoparticle-Sized Bone Substitute
Adhesion to Chemically Treated Peri-Implantitis–Affected Implant
Surfaces: An In Vitro Proof-of-Principle Study
In Vitro
Specificity of Antimicrobial Peptide LL-37 to Neutralize
Periodontopathogenic Lipopolysaccharide Activity in Human Oral
Fibroblasts
In Vitro
Mast Cells Act as Phagocytes Against the Periodontopathogen
Aggregatibacter Actinomycetemcomitans
In Vitro
Erratum: Interleukin-1 Gene Polymorphisms and Chronic Periodontitis
in Adult Whites: A Systematic Review and Meta-Analysis
Erratum
Letter to the Editor: Re: “Real-Time Quantitative Polymerase Chain
Reaction Analysis of Patients With Refractory Chronic Periodontitis”
Letter to the
Editor
Letter to the Editor: Authors’ Response Letter to the
Editor
Clinical Effects of Potassium–Titanyl–Phosphate Laser and
Photodynamic Therapy on Outcomes of Treatment of Chronic
Periodontitis: A Randomized Controlled Clinical Trial
Randomized
Controlled
Clinical Trial

61

Cyanoacrylate Versus Laser in the Treatment of Dentin
Hypersensitivity: A Controlled, Randomized, Double-Masked and Non-
Inferiority Clinical Trial
Randomized
Controlled
Clinical Trial
Is Surgical Root Coverage Effective for the Treatment of Cervical
Dentin Hypersensitivity? A Systematic Review
Systematic
Review
1% Alendronate Gel as Local Drug Delivery in the Treatment of Class II
Furcation Defects: A Randomized Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Role of Space Provision in Regeneration of Localized Two-Wall
Intrabony Defects Using Periosteal Pedicle Graft as an Autogenous
Guided Tissue Membrane
Randomized
Controlled
Clinical Trial
The Clinical Effect of Scaling and Root Planing and the Concomitant
Administration of Systemic Amoxicillin and Metronidazole: A Systematic
Review
Systematic
Review
Effect of Recombinant Human Bone Morphogenetic Protein 2
Associated With a Variety of Bone Substitutes on Vertical Guided Bone
Regeneration in Rabbit Calvarium
Animal
Efficacy of Using PDGF and Xenograft With or Without Collagen
Membrane for Bone Regeneration Around Immediate Implants With
Induced Dehiscence-Type Defects: A Microcomputed Tomographic
Study in Dogs
Animal
Progression of Periodontal Destruction and the Roles of Advanced
Glycation End Products in Experimental Diabetes
Experimental
Stimulation of Periodontal Ligament Stem Cells by Dentin Matrix
Protein 1 Activates Mitogen-Activated Protein Kinase and Osteoblast
Differentiation
In Vitro
Periodontal and Systemic Responses in Various Mice Models of
Experimental Periodontitis: Respective Roles of Inflammation Duration
and Porphyromonas gingivalis Infection
Animal
Maternal Periodontal Disease in Rats Decreases Insulin Sensitivity and
Insulin Signaling in Adult Offspring
Animal

62

Comparative Study of Chinese Hamster Ovary Cell Versus Escherichia
coli-Derived Bone Morphogenetic Protein-2 Using the Critical-Size
Supraalveolar Peri-Implant Defect Model
Animal
2012 Research Forum Poster Session Abstracts Research
Abstracts
American Academy of Periodontology Statement on the Use of Moderate
Sedation by Periodontists
Academt
Statement
Academy Report: Peri-Implant Mucositis and Peri-Implantitis: A
Current Understanding of Their Diagnoses and Clinical Implications
Academy
Report
Enamel Matrix Derivative, Alone or Associated With a Synthetic Bone
Substitute, in the Treatment of 1- to 2-Wall Periodontal Defects
Randomized
Clinical Trial
Platelet-Derived Growth Factor Promotes Periodontal Regeneration in
Localized Osseous Defects: 36-Month Extension Results From a
Randomized, Controlled, Double-Masked Clinical Trial
Randomized
Controlled
Clinical Trial
A Systematic Review of the Use of Growth Factors in Human
Periodontal Regeneration
Systematic
Review
Inferior Alveolar Neurosensory Deficiency Associated With Placement
of Dental Implants
Case Series
Splinted and Unsplinted Short Implants in Mandibles: A Retrospective
Evaluation With 5 to 16 Years of Follow-Up
Experimental
Soft-Tissue Alterations Following Exposure to Tooth-Whitening Agents In Vitro
Opposing Effects of Diabetes and Tetracycline on the Degradation of
Collagen Membranes in Rats
Animal
Toll-Like Receptor 2 Knockdown Modulates Interleukin (IL)-6 and IL-8
but not Stromal Derived Factor-1 (SDF-1/CXCL12) in Human
Periodontal Ligament and Gingival Fibroblasts
In Vitro
Kaempferol Inhibits P. intermedia Lipopolysaccharide-Induced
Production of Nitric Oxide Through Translational Regulation in Murine
Macrophages: Critical Role of Heme Oxygenase-1-Mediated ROS
Reduction
In Vitro

63

Adjunctive Antimicrobial Photodynamic Treatment of Experimentally
Induced Periodontitis in Rats With Ovariectomy
Animal
Clarification/Erratum: The Use of Conscious Sedation by Periodontists Clarification /
Erratum
Clarification/Erratum: Guidelines: In-Office Use of Conscious Sedation
in Periodontics
Clarification /
Erratum
Infection and inflammatory mechanisms Literature
Review
Periodontal systemic associations: review of the evidence Literature
Review
Periodontitis and systemic diseases: a record of discussions of working
group 4 of the Joint EFP/AAP Workshop on Periodontitis and Systemic
Diseases
Workshop
Overview
Periodontitis and atherosclerotic cardiovascular disease: consensus
report of the Joint EFP/AAPWorkshop on Periodontitis and Systemic
Diseases
Consensus
Report
Periodontal bacterial invasion and infection: contribution to
atherosclerotic pathology
Literature
Review
Inflammatory mechanisms linking periodontal diseases to
cardiovascular diseases
Literature
Review
The epidemiological evidence behind the association between
periodontitis and incident atherosclerotic cardiovascular
Systematic
Review
Evidence that periodontal treatment improves biomarkers and CVD
outcomes
Systematic
Review
Diabetes and periodontal diseases: consensus report of the Joint
EFP/AAP Workshop on Periodontitis and Systemic Diseases
Consensus
Report
A review of the evidence for pathogenic mechanisms that may link
periodontitis and diabetes
Literature
Review
Effect of periodontal disease on diabetes: systematic review of
epidemiologic observational evidence
Systematic
Review

64

Evidence that periodontal treatment improves diabetes outcomes: a
systematic review and meta-analysis
Systematic
Review
Periodontitis and adverse pregnancy outcomes: consensus report of the
Joint EFP/AAP Workshop on Periodontitis and Systemic Diseases
Consensus
Report
Adverse pregnancy outcomes (APOs) and periodontal disease:
pathogenic mechanisms
Literature
Review
Epidemiology of association between maternal periodontal disease and
adverse pregnancy outcomes – systematic review
Systematic
Review
The effects of periodontal treatment on pregnancy outcomes Literature
Review
List of workshop chairs, participants, and reviewers Workshop
Information
Corrigendum Corrigendum
Practice Based Research Networks Impacting Periodontal Care: PEARL
Initiative
Commentary
Histologic Comparison of Healing Following Tooth Extraction With
Ridge Preservation Using Two Different Xenograft Protocols
Randomized
Clinical Trial
Periodontal Diagnosis Affected by Variation in Terminology Randomized
Case
Presentation
Matrix Metalloproteinases, Tissue Inhibitors of Matrix
Metalloproteinases, and Inflammation in Cyclosporine A–Induced
Gingival Enlargement: A Pilot In Vitro Study Using a Three-
Dimensional Model of the Human Oral Mucosa
In Vitro
Laser Therapy as an Effective Method for Implant Surface
Decontamination: A Histomorphometric Study in Rats
Animal
Porphyromonas gingivalis HmuY-Induced Production of Interleukin-6
and IL-6 Polymorphism in Chronic Periodontitis
In Vitro

65

Doxycycline Counteracts Bone Morphogenic Protein 2–Induced
Osteogenic Mediators
In Vitro
Therapeutic Effects of Alpha Lipoic Acid and Vitamin C on Alveolar
Bone Resorption After Experimental Periodontitis in Rats: A
Biochemical, Histochemical, and Stereologic Study
Animal
Tumor Necrosis Factor-α Inhibits Transforming Growth Factor-β–
Stimulated Myofibroblastic Differentiation and Extracellular Matrix
Production in Human Gingival Fibroblasts
In Vitro
Tumor Necrosis Factor-α and Porphyromonas gingivalis
Lipopolysaccharides Decrease Periostin in Human Periodontal
Ligament Fibroblasts
In Vitro
Collinin Reduces Porphyromonas gingivalis Growth and Collagenase
Activity and Inhibits the Lipopolysaccharide-Induced Macrophage
Inflammatory Response and Osteoclast Differentiation and Function
In Vitro
Peer Review Panel and Ad Hoc Reviewers for the Journal of
Periodontology
Peer Review
Are There Specific Benefits of Amoxicillin Plus Metronidazole in
Aggregatibacter actinomycetemcomitans-Associated Periodontitis?
Double-Masked, Randomized Clinical Trial of Efficacy and Safety
Randomized
Clinical Trial
Bone-to-Implant Contact Around Immediately Loaded Direct Laser
Metal-Forming Transitional Implants in Human Posterior Maxilla
Experimental
Comparison of Surgical Stripping; Erbium-Doped:Yttrium, Aluminum,
and Garnet Laser; and Carbon Dioxide Laser Techniques for Gingival
Depigmentation: A Clinical and Histologic Study
Experimental
Ten-Year Results Following Treatment of Intrabony Defects With an
Enamel Matrix Protein Derivative Combined With Either a Natural
Bone Mineral or a β-Tricalcium Phosphate
Data from
Randomized
Controlled
Clinical Trial
Quality Assessment of Systematic Reviews on Short Dental Implants Quality
Assessment
Effect of Surgical Defect Coverage on Cervical Dentin Hypersensitivity
and Quality of Life
Experimental

66

Effect of Hydrosoluble Chlorine–Mediated Antimicrobial Photodynamic
Therapy on Clinical Parameters and Cytokine Profile in Ligature-
Induced Periodontitis in Dogs
Animal
Bacterial Antagonism Against Periodontopathogens In Vitro
Comparison Between a β-Tricalcium Phosphate and an Absorbable
Collagen Sponge Carrier Technology for rhGDF-5–Stimulated
Periodontal Wound Healing/Regeneration
Animal
Bone Morphogenic Protein-2 Induces Apoptosis and Cytotoxicity in
Periodontal Ligament Cells
In Vitro
Effects of Estrogen Deficiency and/or Caffeine Intake on Alveolar Bone
Loss, Density, and Healing: A Study in Rats
Animal
rgpA DNA Vaccine Induces Antibody Response and Prevents Alveolar
Bone Loss in Experimental Peri-Implantitis
Experimental
Initial Periodontal Treatment for Prevention of Chronic Obstructive
Pulmonary Disease Exacerbations
Controlled
Clinical Trial
Clinical Efficacy of Subgingivally Delivered 1.2% Atorvastatin in
Chronic Periodontitis: A Randomized Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Long-Term Follow-Up of Turned Single Implants Placed in
Periodontally Healthy Patients After 16 to 22 Years: Microbiologic
Outcome
Data from
Case Series
Are Short Dental Implants (<10 mm) Effective? A Meta-Analysis on
Prospective Clinical Trials
Meta-
Analysis
Enhancing Guided Tissue Regeneration of Periodontal Defects by Using
a Novel Perforated Barrier Membrane
Randomized
Clinical Trial
Vestibuloplasty: Porcine Collagen Matrix Versus Free Gingival Graft:
A Clinical and Histologic Study
Experimental
Doxycycline-Loaded β-Tricalcium Phosphate Release Following EDTA
Root Surface Etching Improved the Clinical Outcomes in Chronic
Periodontitis: An In Vivo Study
Randomized
Controlled
Clinical Trial

67

Evaluation of Supracrestal Gingival Tissue After Surgical Crown
Lengthening: A 6-Month Clinical Study
Experimental
Hyaluronic Acid as an Adjunct After Scaling and Root Planing: A
Prospective Randomized Clinical Trial
Randomized
Clinical Trial
Use of a Collagen Membrane Loaded With Recombinant Human Bone
Morphogenetic Protein-2 With Collagen-Binding Domain for Vertical
Guided Bone Regeneration
Animal
Effectiveness of Periodontal Treatment to Improve Metabolic Control in
Patients With Chronic Periodontitis and Type 2 Diabetes: A Meta-
Analysis of Randomized Clinical Trials
Meta-
Analysis
Aggressive Periodontitis Defined by Recursive Partitioning Analysis of
Immunologic Factors
Descriptive
Ex Vivo Bone Morphogenetic Protein-2 Gene Delivery Using Bone
Marrow Stem Cells in Rabbit Maxillary Sinus Augmentation in
Conjunction With Implant Placement
Animal
Comparative Studies on Microvascular Endothelial Cells Isolated From
Periodontal Tissue
In Vitro
Induction of Toll-Like Receptor Expression by Porphyromonas
gingivalis
In Vitro
Protective Potential of Non-Dialyzable Material Fraction of Cranberry
Juice on the Virulence of P. gingivalis and F. nucleatum Mixed Infection
In Vitro
Antibiotic Susceptibility of Periodontal Enterococcus faecalis In Vitro
2012 Balint Orban Memorial Program Abstracts – Basic Research Research
Abstracts
Beneficial Effects of Hormone Replacement Therapy on Periodontitis
Are Vitamin D Associated
In Vitro
A Randomized, Double-Masked Clinical Trial Comparing Four
Periodontitis Treatment Strategies: 1-Year Clinical Results
Randomized
Clinical Trial
Palatonasal Recess on Medial Wall of the Maxillary Sinus and Clinical
Implications for Sinus Augmentation via Lateral Window Approach
Descriptive

68

Effect of Maxillary Sinus Membrane Perforation on Vital Bone
Formation and Implant Survival: A Retrospective Study
Data from
Clinical Trial
Treatment of Supra-Alveolar-Type Defects by a Simplified Papilla
Preservation Technique for Access Flap Surgery With or Without
Enamel Matrix Proteins
Randomized
Controlled
Clinical Trial
Clinical Effectiveness of Diode Laser Therapy as an Adjunct to Non-
Surgical Periodontal Treatment: A Randomized Clinical Study
Randomized
Clinical Trial
Protective Mechanisms of Simvastatin in Experimental Periodontal
Disease
Experimental
Locally Delivered 1% Metformin Gel in the Treatment of Smokers with
Chronic Periodontitis: A Randomized Controlled Clinical Trial
Randomized
Controlled
Clinical Trial
Efficacy of Acellular Dermal Matrix and Coronally Advanced Flaps for
the Treatment of Induced Gingival Recession Defects: A
Histomorphometric Study in Dogs
Animal
Plasma Rich in Growth Factors Promotes Bone Tissue Regeneration by
Stimulating Proliferation, Migration, and Autocrine Secretion in
Primary Human Osteoblasts
In Vitro
In Vitro Analysis of the Efficacy of Ultrasonic Scalers and a Toothbrush
for Removing Bacteria from Resorbable Blast Material Titanium Disks
In Vitro
Progression of Osteogenic Cell Cultures Grown on Microtopographic
Titanium Coated With Calcium Phosphate and Functionalized With a
Type I Collagen-Derived Peptide
In Vitro
Effect of Essential Oil and Chlorhexidine Mouthwashes on Gingival
Fibroblast Survival and Migration
In Vitro
The Effects of a Novel Botanical Agent on Lipopolysaccharide-Induced
Alveolar Bone Loss in Rats
Animal
Letter to the Editor: Re: “Periodontal Diagnosis Affected by Variation
in Terminology”
Letter to the
Editor
Letter to the Editor: Authors’ response Letter to the
Editor

69

Rehabilitation of Deficient Alveolar Ridges Using Titanium Grids
Before and Simultaneously With Implant Placement: A Systematic
Review
Systematic
Review
Randomized Controlled Clinical Trial Evaluating Connective Tissue
Graft Plus Resin-Modified Glass Ionomer Restoration for the Treatment
of Gingival Recession Associated With Non-Carious Cervical Lesion: 2-
Year Follow-Up
Randomized
Controlled
Clinical Trial
Host Genome, Epigenome, and Oral Microbiome Interactions: Toward
Personalized Periodontal Therapy
Commentary
Effect of Porphyromonas gingivalis on Citrullination of Proteins by
Macrophages In Vitro
In Vitro
Periodontal Tissue and Serum Concentration of Clarithromycin After
Systemic Administration in Patients Affected by Chronic Periodontitis
Experimental
Thermo-Reversible Green Tea Catechin Gel for Local Application in
Chronic Periodontitis: A 4-Week Clinical Trial
Experimental
Boric Acid Irrigation as an Adjunct to Mechanical Periodontal Therapy
in Patients With Chronic Periodontitis: A Randomized Clinical Trial
Randomized
Clinical Trial
Histometric Analysis of the Effect of Enamel Matrix Derivative on the
Healing of Periodontal Defects in Rats With Diabetes
Animal
Orthodontic Force Increases Interleukin-1β and Tumor Necrosis
Factor-α Expression and Alveolar Bone Loss in Periodontitis
Animal
Blocking Proinflammatory Cytokine Release Modulates Peripheral
Blood Mononuclear Cell Response to Porphyromonas gingivalis
In Vitro
Inhibition of Transforming Growth Factor β1/Smad3 Signaling
Decreases Hypoxia-Inducible Factor-1α Protein Stability by Inducing
Prolyl Hydroxylase 2 Expression in Human Periodontal Ligament Cells
In Vitro
MyD88 or TRAM Knockdown Regulates Interleukin (IL)-6, IL-8, and
CXCL12 mRNA Expression in Human Gingival and Periodontal
Ligament Fibroblasts
In Vitro
2012 Balint Orban Memorial Program Abstracts – Clinical Research Research
Abstracts

70

The Association Between Clinical and Radiographic Periodontitis
Measurements During Periodontal Maintenance
Data from
Randomized
Controlled
Clinical Trial
Intrapregnancy Non-Surgical Periodontal Treatment and Pregnancy
Outcome: A Randomized Controlled Trial
Randomized
Controlled
Clinical Trial
Efficacy of Collagen Membrane Seeded With Autologous Gingival
Fibroblasts in Gingival Recession Treatment: A Randomized, Controlled
Pilot Study
Randomized
Controlled
Clinical Trial
Mathematical Modeling Suggests That Periodontitis Behaves as a Non-
Linear Chaotic Dynamical Process
Descriptive
Effect of Nanoscale Topography of Titanium Implants on Bone Vessel
Network, Osteocytes, and Mineral Densities
Randomized
Controlled
Clinical Trial
Periodontal Ligament Stem Cells Possess the Characteristics of
Pericytes
In Vitro
Optimal Medium Formulation for the Long-Term Expansion and
Maintenance of Human Periodontal Ligament Stem Cells
In Vitro
Orally Administered Liposomal Lactoferrin Inhibits Inflammation-
Related Bone Breakdown Without Interrupting Orthodontic Tooth
Movement
Animal
Resveratrol Decreases Periodontal Breakdown and Modulates Local
Levels of Cytokines During Periodontitis in Rats
Animal
Virulence Mechanism of Bacteria in Mixed Infection: Attenuation of
Cytokine Levels and Evasion of Polymorphonuclear Leukocyte
Phagocytosis
In Vitro
The Upregulation of Transglutaminase-2 by Cyclosporin A in Human
Gingival Fibroblasts Is Augmented by Oxidative Stress
In Vitro
A Synthetic Oligopeptide Derived From Enamel Matrix Derivative
Promotes the Differentiation of Human Periodontal Ligament Stem
Cells Into Osteoblast-Like Cells With Increased Mineralization
In Vitro

71

The Influence of β-Tricalcium Phosphate Blocks Containing
Extracellular Matrix on Osteogenic Differentiation of Rat Bone Marrow
Stromal Cells
In Vitro
Oral Neutrophils Display a Site-Specific Phenotype Characterized by
Expression of T-Cell Receptors
Descriptive
Regulation of Periodontal Ligament Cell Behavior by Cyclic
Mechanical Loading and Substrate Nanotexture
In Vitro
Obituary: Henry M. Swenson, DDS Obituary
Five-Year Results Evaluating the Effects of Platelet-Rich Plasma on the
Healing of Intrabony Defects Treated With Enamel Matrix Derivative
and Natural Bone Mineral
Data from
Randomized
Controlled
Clinical Trial
An Autologous Platelet-Rich Plasma Stimulates Periodontal Ligament
Regeneration
In Vitro
Ridge Preservation Comparing Socket Allograft Alone to Socket
Allograft Plus Facial Overlay Xenograft: A Clinical and Histologic
Study in Humans
Randomized
Controlled
Clinical Trial
Coronally Advanced Flap Alone or With Connective Tissue Graft in the
Treatment of Single Gingival Recession Defects: A Long-Term
Randomized Clinical Trial
Randomized
Controlled
Clinical Trial
The Frequency of Peri-Implant Diseases: A Systematic Review and
Meta-Analysis
Systematic
Review &
Meta-
Analysis
implified Drilling Technique Does Not Decrease Dental Implant
Osseointegration: A Preliminary Report
Animal
A 3-Day Randomized Clinical Trial to Investigate the Desensitizing
Properties of Three Dentifrices
Randomized
Clinical Trial
Epigenetic Regulation of TNFA Expression in Periodontal Disease Experimental

72

Periodontitis as a Novel Contributor of Adipose Tissue Inflammation
Promotes Insulin Resistance in a Rat Model
Animal
Discriminant Analysis for the Thin Periodontal Biotype Based on the
Data Acquired From Three-Dimensional Virtual Models of Korean
Young Adults
Descriptive
In Vitro Evaluation of Demineralized Freeze-Dried Bone Allograft in
Combination With Enamel Matrix Derivative
In Vitro
Analysis of Occlusal Stresses Transmitted to the Inferior Alveolar Nerve
by Multiple Threaded Implants
Descriptive
In Situ Chlorhexidine Substantivity on Saliva and Plaque-Like Biofilm:
Influence of Circadian Rhythm
In Vitro
Effects of Tacrolimus and Nifedipine, Alone or in Combination, on
Gingival Tissues
Animal
Triclosan Blocks MMP-13 Expression in Hormone-Stimulated
Osteoblasts
In Vitro
Lactoferrin Knockout Mice Demonstrates Greater Susceptibility to
Aggregatibacter actinomycetemcomitans–Induced Periodontal Disease
Animal
AAP President’s Address AAP Address
Peer Review Panel and Ad Hoc Reviewers for the Journal of
Periodontology
Peer Review
Mixed Nano/Micro-Sized Calcium Phosphate Composite and EDTA
Root Surface Etching Improve Availability of Graft Material in
Intrabony Defects: An In Vivo Scanning Electron Microscopy
Evaluation
Randomized
Clinical Trial
Periodontal Probing of Dental Furcations Compared With Diagnosis by
Low-Dose Computed Tomography: A Case Series
Case Series
Effect of Flapless Surgery on Single-Tooth Implants in the Esthetic
Zone: A Randomized Clinical Trial
Randomized
Clinical Trial

73

The Significance of Keratinized Mucosa on Implant Health: A
Systematic Review
Systematic
Review
Implant–Buccal Plate Distance as Diagnostic Parameter: A Prospective
Cohort Study on Implant Placement in Fresh Extraction Sockets
Data from
Experimental
Study
Do Implant Length and Width Matter for Short Dental Implants (<10
mm)? A Meta-Analysis of Prospective Studies
Meta-
Analysis
Periodontal Treatment Reduces Matrix Metalloproteinase Levels in
Localized Aggressive Periodontitis
Experimental
Periodontal Treatment Decreases Levels of Antibodies to
Porphyromonas gingivalis and Citrulline in Patients With Rheumatoid
Arthritis and Periodontitis
Randomized
Clinical Trial
Probiotic Therapy Reduces Periodontal Tissue Destruction and
Improves the Intestinal Morphology in Rats With Ligature-Induced
Periodontitis
Animal
Effects of Resolvin D1 on Cell Survival and Cytokine Expression of
Human Gingival Fibroblasts
In Vitro
Coculture With Endothelial Cells Enhances Osteogenic Differentiation
of Periodontal Ligament Stem Cells via Cyclooxygenase-
2/Prostaglandin E2/Vascular Endothelial Growth Factor Signaling
Under Hypoxia
In Vitro
Peptides: β-Cyclodextrin Inclusion Compounds as Highly Effective
Antimicrobial and Anti-Epithelial Proliferation Agents
In Vitro

74

Table 3. Included Studies with Reason for Inclusion
Title Reason for
inclusion
Periodontal Status and Hyperlipidemia: Statin Users Versus Non-Users Cross-
sectional
Changes in Inflammatory and Metabolic Parameters After Periodontal
Treatment in Patients With and Without Obesity
Prospective
Cohort
Alveolar Bone Loss Associated With Age-Related Macular Degeneration
in Males
Cross-
sectional
Exfoliative Cytology and Titanium Dental Implants: A Pilot Study Case Control
Proinflammatory and Anti-Inflammatory Cytokines in Gingival
Crevicular Fluid and Serum of Patients With Rheumatoid Arthritis and
Patients With Chronic Periodontitis
Cross-
sectional
Relationship Between Normal Serum Creatinine Concentration and
Periodontal Disease in Japanese Middle-Aged Males
Cross-
sectional
Individual Composition of Human Leukocyte Antigens and
Periodontopathogens in the Background of Periodontitis
Cross-
sectional
Periodontal Condition of Patients With Autoimmune Diseases and the
Effect of Anti-Tumor Necrosis Factor-α Therapy
Cross-
sectional
Severe Preeclampsia and Maternal Self-Report of Oral Health, Hygiene,
and Dental Care
Prospective
Cohort
Evaluation of the Effects of Buccal–Palatal Bone Width on the Incidence
and Height of the Interproximal Papilla Between Adjacent Implants in
Esthetic Areas
Cross-
sectional
Periodontal Disease, Hypertension, and Blood Pressure Among Older
Adults in Puerto Rico
Cross-
sectional
Innate Immune Receptor Expression in Peri-Implant Tissues of Patients
With Different Susceptibility to Periodontal Diseases
Prospective
Cohort
Mast Cell Degranulation in Human Periodontitis Cross-
sectional

75

Changes in Masticatory Performance and Quality of Life in Individuals
With Chronic Periodontitis
Case Control
Severe Loss of Clinical Attachment Level: An Independent Association
With Low Hip Bone Mineral Density in Postmenopausal Females
Cross-
sectional
Profiles of Dental Caries and Periodontal Disease in Individuals With
or Without Psoriasis
Case Control
Peripheral Arterial Disease Associated With Caries and Periodontal
Disease
Case Control
Elevated Levels of a Disintegrin and Metalloproteinase 8 in Gingival
Crevicular Fluid of Patients With Periodontal Diseases
Cross-
sectional
Five-Year Changes in Periodontal Disease Measures Among
Postmenopausal Females: The Buffalo OsteoPerio Study
Prospective
Cohort
Progression of Periodontitis and Tooth Loss Associated with Glycemic
Control in Individuals Undergoing Periodontal Maintenance Therapy: A
5-Year Follow-Up Study
Case Control
Potential Association of Paraoxonase-1, Type 2 Diabetes Mellitus, and
Periodontitis
Cross-
sectional
Local and Circulating Levels of Adipocytokines in Obese and Normal
Weight Individuals With Chronic Periodontitis
Cross-
sectional
Serum Levels of Long-Chain Polyunsaturated Fatty Acids in Patients
With Periodontal Disease
Cross-
sectional
Change of Periodontal Disease Status During and After Pregnancy Prospective
Cohort
Association Between Periodontitis and Salivary Nitric Oxide
Metabolites Among Community Elderly Koreans
Cross-
sectional
Effect of Chronic Periodontitis on Oxidative Status in Patients With
Rheumatoid Arthritis
Cross-
sectional
8-Hydroxy-Deoxyguanosine Levels in Gingival Crevicular Fluid and
Saliva in Patients With Chronic Periodontitis After Initial Periodontal
Treatment
Case Control

76

Periodontitis and Gestational Diabetes Mellitus in Non-Smoking
Females
Case Control
Mast Cells in Periodontal Disease of Individuals With and Without HIV
Undergoing Highly Active Antiretroviral Therapy
Case Control
Radiographic Analysis of a Transalveolar Sinus-Lift Technique: A
Multipractice Retrospective Study With a Mean Follow-Up of 5 Years
Retrospective
Cohort
The Sociodemographic Characteristics, Periodontal Health Status, and
Subgingival Microbiota of Patients With Chronic Periodontitis and Type
2 Diabetes Mellitus: A Case-Control Study in a Chinese Population
Case Control
Prevalence and Severity of Periodontitis in Indonesian Patients With
Rheumatoid Arthritis
Case Control
Periodontal Disease and Pregnancy Hypertension: A Clinical
Correlation
Case Control
The Effect of Esthetic Crown Lengthening on Perceptions of a Patient’s
Attractiveness, Friendliness, Trustworthiness, Intelligence, and Self-
Confidence
Case Control
Tooth Loss and Periodontitis in Older Individuals: Results From the
Swedish National Study on Aging and Care
Cross-
sectional
Periodontal Inflammatory Conditions Among Gutka Chewers and Non-
chewers With and Without Prediabetes
Cross-
sectional
Plasma 25-Hydroxyvitamin D Concentrations and Periodontal Disease
in Postmenopausal Women
Cross-
sectional
Association Between Periodontitis and Gestational Diabetes Mellitus: A
Case-Control Study
Case Control
Suppuration-Associated Bacteria in Patients With Chronic and
Aggressive Periodontitis
Cross-
sectional
High Salivary Estrogen and Risk of Developing Pregnancy Gingivitis Prospective
Cohort
Increased Levels of Serum and Gingival Crevicular Fluid Monocyte
Chemoattractant Protein-1 in Smokers With Periodontitis
Cross-
sectional

77

Are Periodontal Bacterial Profiles and Placental Inflammatory Infiltrate
in Pregnancy Related to Birth Outcomes?
Case Control
Treatment Outcome in Patients With Peri-Implantitis in a Periodontal
Clinic: A Retrospective Study
Retrospective
Cohort
Periodontal and General Health in Long-Term Periodontal
Maintenance Patients Treated in a Norwegian Private Practice: A
Descriptive Report From a Compliant and Partially Compliant Survivor
Population
Retrospective
Cohort
Influence of Dyslipidemia and Diabetes Mellitus on Chronic Periodontal
Disease
Cross-
sectional
Predictive Power of the Severity Measure of Attachment Loss for
Periodontal Care Need
Cross-
sectional
Increased Nucleic Acid Receptor Expression in Chronic Periodontitis Case Control
Influence of Periodontal Status and Periodontopathogens on Levels of
Oral Human β-Defensin-2 in Saliva
Cross-
sectional
Long-Term Stability of Contour Augmentation With Early Implant
Placement Following Single Tooth Extraction in the Esthetic Zone: A
Prospective, Cross-Sectional Study in 41 Patients With a 5- to 9-Year
Follow-Up
Cross-
sectional
Factors Affecting Treatment Decisions and Outcomes of Root-Resected
Molars: A Nationwide Study
Retrospective
Cohort
New Attempts to Modify Periodontal Risk Assessment for Generalized
Aggressive Periodontitis: A Retrospective Study
Retrospective
Cohort
Gingival Crevicular Fluid, Serum Levels of Receptor Activator of
Nuclear Factor-κB Ligand, Osteoprotegerin, and Interleukin-17 in
Patients With Rheumatoid Arthritis and Osteoporosis and With
Periodontal Disease
Cross-
sectional
Association Between Low Bone Mineral Density and Clinical
Attachment Loss in Japanese Postmenopausal Females
Cross-
sectional
Association Between Periodontal Disease and Chronic Obstructive
Pulmonary Disease: A Reality or Just a Dogma?
Case Control

78

Salivary Cotinine Concentrations and Prevalence of Periodontal
Disease in Young Japanese Women: The Kyushu Okinawa Maternal and
Child Health Study
Cross-
sectional
Implant Survival and Marginal Bone Loss at Turned and Oxidized
Implants in Periodontitis-Susceptible Smokers and Never-Smokers: A
Retrospective, Clinical, Radiographic Case-Control Study
Case Control

Diabetes-Associated Periodontitis Molecular Features in Infrared
Spectra of Gingival Crevicular Fluid
Case Control
Subgingival Bacterial Burden in Relation to Clinical and Radiographic
Periodontal Parameters
Cross-
sectional
Is Interleukin-17 Involved in the Interaction Between Polycystic Ovary
Syndrome and Gingival Inflammation?
Cross-
sectional

79

Figure 4. Percentage of cohort, case-control, and cross-sectional studies included in the
current analyses

Figure 5. Average percentage of properly addressed STROBE items per article section

10%
8%
31%
51%
Prospective Cohort
Retrospective Cohort
Case-Control
Cross-sectional
0 10 20 30 40 50 60 70 80 90 100
Title and Abstract
Introduction
Methods
Results
Discussion
Other
Percentage Compliance
Article Section
Average Percentage of Properly Addressed Items Per
Section

80

Figure 6. Average percentage of properly addressed STROBE items in the Title,
Abstract, and Introduction

Figure 7. Average percentage of compliance to Strobe item 1 Components

0
10
20
30
40
50
60
70
80
90
100
1 2 3
Percentage Compliance
Strobe Item
Title, Abstract, & Introduction Sections Compliance
0 10 20 30 40 50 60 70 80 90 100
1a
1b
Percentage Compliance
STROBE Item
Compliance to Item 1 Components

81

Figure 8. The mention of study design within the included 59 articles

Figure 9. Location of mention study design within the selected 59 articles

0% 10% 20% 30% 40% 50% 60%
Yes
No
Percentage
Article Mention of Study Design
74%

4%

15%

4%

4%

Location
of
Mentioned
Study
Design

Abstract
&
Title

Introduction

Methods

Discussion

Conclusion

82

Figure 10. Average percentage of properly addressed STROBE items in the Methods
section

Figure 11. Average percentage of compliance to Strobe item 6 Components

0
10
20
30
40
50
60
70
80
90
100
4 5 6 7 8 9 10 11 12
Percentage Compliance
Strobe Item
Methods Section Compliance
0 10 20 30 40 50 60 70 80 90 100
6a
6b
Percentage Compliance
Strobe Item
Compliance to Item 6 Components

83

Figure 12. Average percentage of compliance to Strobe item 12 Components

Figure 13. Average percentage of properly addressed STROBE items in the Results
section

0 10 20 30 40 50 60 70 80 90 100
12a
12b
12c
12d
12e
Percentage Compliance
Strobe Item
Compliance to Item 12 Components
0
10
20
30
40
50
60
70
80
90
100
13 14 15 16 17
Percentage Compliance
Strobe Item
Results Section Compliance

84

Figure 14. Average percentage of compliance to Strobe item 13 Components

Figure 15. Average percentage of compliance to Strobe item 14 Components

0 10 20 30 40 50 60 70 80 90 100
13a
13b
13c
Percentage Compliance
Strobe Item
Compliance to Item 13 Components
0 10 20 30 40 50 60 70 80 90 100
14a
14b
14c
Percentage Compliance
Strobe Item
Compliance to Item 14 Components

85

Figure 16. Average percentage of compliance to Strobe item 16 Components

Figure 17. Average percentage of properly addressed STROBE items in the Discussion
and Other sections

0 10 20 30 40 50 60 70 80 90 100
16a
16b
Percentage Compliance
Strobe Item
Compliance to Item 16 Components
0
10
20
30
40
50
60
70
80
90
100
18 19 20 21 22
Percentage Compliance
Strobe Item
Discussion & Other Sections Compliance

86

Figure 18. Average percentage of properly addressed STROBE items

Figure 19. Distribution of average compliance of each article against the STROBE
checklist

0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Percentage (%)
Strobe Itme
Average Compliance to the STROBE Checklist Items
0

5

10

15

20

25

30

35

50-‐59%
60-‐69%
70-‐79%
80-‐89%
90-‐99%

Number
of
Papers

Average
Percentage
Compliance

Distribution
of
Compliance
of
All
Papers

87

Figure 20. Distribution of average compliance of the included articles above and below
75% against the STROBE checklist

Figure 21. Distribution of average compliance of the included articles above and below
85% against the STROBE checklist

75%
25%
Avergae Compliance of Papers Above and Below 75%
50-74%
75-100%
98%
2%
Average Compliance of Papers Above and Below 85%
50-84%
85-100%

Asset Metadata

Creator Costandi, Diane (author)

Core Title Assessment of the quality of reporting observational studies in periodontal literature

Contributor Electronically uploaded by the author (provenance)

School School of Dentistry

Degree Master of Science

Degree Program Craniofacial Biology

Publication Date 07/09/2015

Defense Date 05/14/2015

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag case-control,cohort,cross-sectional,OAI-PMH Harvest,observational study,strengthening the reporting of observational studies in epidemiology (STROBE)

Format application/pdf (imt)

Language English

Advisor Kar, Kian (committee chair), Paine, Michael L. (committee member), Sameshima, Glenn T. (committee member)

Creator Email dgacostandi@gmail.com,dganthon@usc.edu

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c3-590048

Unique identifier UC11301310

Identifier etd-CostandiDi-3578.pdf (filename),usctheses-c3-590048 (legacy record id)

Legacy Identifier etd-CostandiDi-3578.pdf

Dmrecord 590048

Document Type Thesis

Format application/pdf (imt)

Rights Costandi, Diane

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA

Abstract (if available)

Abstract Background: Observational studies intend to examine variables in a population with hopes of characterizing any potential associations. Thus, the quality of reporting of observational studies is important in evidence-based clinical decision-making processes. Comparison of the reporting quality to established standards can help identify short comings of a study and aim to improve quality of reporting and relevance of the published data in clinical decision making. ❧ Purpose: To assess the quality of reporting of observational studies in a widely read periodontology journal, the Journal of Periodontology (JoP). ❧ Methods: Electronic search, supplemented by hand search of JoP was completed independently and in duplicate by two reviewers. The combined strengthening the reporting of observational studies in epidemiology (STROBE) statement and checklist (consisting of 22 criteria) were used to evaluate the reporting quality of the selected observational studies from JoP published in the year of 2013. ❧ Results: STROBE items 9 (publication bias), 10 (study size determination), 12e (sensitivity analysis), 13c (diagram usage),19 (limitations), and 22 (funding of the study) were consistently scored low in the journal, whereas items 2 (background), 5 (setting of the study), 6 (participants of the study), 8 (data measurement), 15 (outcome data), and 18 (key results) were consistently scored high. ❧ Conclusion: The quality of reporting of observational studies in JoP can be improved as compared to the STROBE statement.