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J Dent Educ. 71(6): 825-831 2007
© 2007 American Dental Education Association
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Evidence-Based Dentistry

Evidence-Based Dentistry: A Model for Clinical Practice

Clóvis M. Faggion, Jr., D.D.S.; Yu-Kang Tu, D.D.S., M.Sc., Ph.D.

Key words: evidence-based dentistry, decision making, clinical practice, model

Submitted for publication 08/10/06; accepted 02/14/07


   Abstract
Top
 Abstract
Material and Methods
 Results
 Discussion
 References
 
Making decisions in dentistry should be based on the best evidence available. The objective of this study was to demonstrate a practical procedure and model that clinicians can use to apply the results of well-conducted studies to patient care by critically appraising the evidence with checklists and letter grade scales. To demonstrate application of this model for critically appraising the quality of research evidence, a hypothetical case involving an adult male with chronic periodontitis is used as an example. To determine the best clinical approach for this patient, a four-step, evidence-based model is demonstrated, consisting of the following: definition of a research question using the PICO format, search and selection of relevant literature, critical appraisal of identified research reports using checklists, and the application of evidence. In this model, the quality of research evidence was assessed quantitatively based on different levels of quality that are assigned letter grades of A, B, and C by evaluating the studies against the QUOROM (Quality of Reporting Meta-Analyses) and CONSORT (Consolidated Standards of Reporting Trials) checklists in a tabular format. For this hypothetical periodontics case, application of the model identified the best available evidence for clinical decision making, i.e., one randomized controlled trial and one systematic review of randomized controlled trials. Both studies showed similar answers for the research question. The use of a letter grade scale allowed an objective analysis of the quality of evidence. A checklist-driven model that assesses and applies evidence to dental practice may substantially improve dentists’ decision making skill.

The concept of evidence-based practice was introduced into dentistry more than ten years ago.1–3 It has been claimed that the application of results from relevant clinical studies, together with the clinicians’ expertise and patients’ values, may be helpful in making better clinical decisions. There is a trend in dental education curricula towards the evidence-based dentistry (EBD) philosophy. It is believed that students taught with this approach perform better than when the curriculum does not include classroom training and clinical application of EBD concepts and techniques.4

However, some studies have demonstrated that EBD, when taught only in the classroom, may have little impact on the attitudes or behaviors of clinical practitioners.5 In other words, theoretical knowledge of EBD, obtained without opportunities to practice using an evidence-based approach to patient care decision making, may lead to no changes in dental practice at all. Therefore, it is crucial to implement evidence from research into clinical practice, and by doing this, the concept of EBD can become practically relevant to the dentist. However, there is no consensus in the dental literature about the best system for implementing evidence into dental practice. It is important, therefore, to introduce a model of decision making based on the best available evidence to clinicians.

The objective of this study was to demonstrate the application of a clinical decision model, based on the philosophy of evidence-based dentistry to help clinicians implement the EBD process into daily dental practice. Thus, the purpose of this article is to show dental practitioners how to critically evaluate relevant publications selected from a literature search using well-established guidelines such as the Consolidated Standards of Reporting Trials (CONSORT)6 and the Quality of Reporting Meta-Analyses (QUOROM).7 These guidelines were created to improve the reporting of randomized controlled trials and systematic review of randomized controlled trials, respectively.


   Material and Methods
Top
 Abstract
 Material and Methods
Results
 Discussion
 References
 
The standard four-step EBD model was used to find, appraise, and apply research evidence related to the case scenario described below:

  1. definition of a well-constructed question in the PICO format (Patient, Intervention, Comparison, and Outcome);
  2. definition of key words, followed by searching and selecting relevant articles;
  3. critical appraisal of selected literature using the CONSORT and QUOROM checklists; and
  4. application of results to resolve the patient’s health care problems.

However, for EBD step 3, the CONSORT and QUOROM checklists were used to guide appraisal of the identified research reports.

The PICO question was developed from a hypothetical case scenario. A fifty-six-year-old, systematically healthy male patient with chronic periodontitis is looking for treatment. He is afraid of dental procedures and would like to avoid staying long in a dental chair. This information was converted into one well-structured question in the PICO format, which was used to direct the literature searching:

P (patient): adults with chronic periodontitis

I (intervention): periodontal treatment with sonic and ultrasonic scalers

C (comparison): periodontal treatment with manual instruments

O (outcome): effectiveness (measured by clinical attachment gain), pocket probing depth reduction, and efficiency (measured by treatment time)

Therefore, the question was structured as follows: "In adult patients with chronic periodontitis, which nonsurgical periodontal treatment (sonic/ultrasonic scalers or manual instruments) is more effective, in terms of probing pocket depth reduction/attachment level gain, and efficient in terms of duration of treatment?"

To begin the second step, the research of articles was conducted on July 17, 2006, by using the electronic database PubMed/Medline. The following free-text term combinations were used: periodont* AND sonic, periodont* AND power-driven and periodont* AND machine-driven. A search strategy, including controlled vocabulary (MeSH terms), was conducted with terms "periodontitis" and "sonic" in order to compare results of both search strategies. Inclusion criteria for critical appraisal of literature were Randomized Controlled Trials (RCT) and Systematic Reviews of Randomized Controlled Trials (SRRCT) with at least six months follow-up.

The results of the critical appraisal were used to assist with clinical decision making. In other words, the decision of using sonic/ultrasonic scalers or hand instruments was based on evidence from scientific publications.

The CONSORT includes a checklist and flow diagram originally developed by an international group of clinical investigators, statisticians, epidemiologists, and biomedical journal editors to help researchers improve the quality of reporting randomized controlled trials.6 The CONSORT checklist contains items that should be reported by RCTs. After its creation, CONSORT was revised based on feedback from users, and now the checklist includes twenty-two items that assess the quality of each pivotal part of a clinical trial report (title and abstract, introduction, material and methods, results, and discussion).6

The QUOROM checklist was also developed through consensus by a heterogeneous group of health professionals.7 It consists of twenty-one headings and subheadings that assess the quality of various steps necessary for conducting a systematic review, regarding search and selection of studies, validity assessment, data abstraction, study characteristics, and quantitative data synthesis, and for reporting the results regarding the "trial flow," study characteristics and quantitative data synthesis.7

In this study, important sections of the studies that were identified from the review of the literature were compared directly to the items described on both checklists using a functional table as demonstrated below.

Three criteria were used to assess the methodological quality of the research reports. A grade of A was assigned if the assessed topic was in total agreement with checklist recommendations; a grade of B was assigned if the assessed topic was in partial agreement with checklist recommendations; and a grade of C was assigned if the assessed topic was not in agreement with checklist recommendations or there was no reference in the manuscript text about the checklist topic.


   Results
Top
 Abstract
 Material and Methods
 Results
Discussion
 References
 
The literature search identified 148 studies, and 130 were excluded by examining their titles. The abstracts of the remaining eighteen articles were assessed, and two had their full text completely analyzed (Figure 1Go). The reasons for the exclusion of sixteen reports are shown in Table 1Go.


Figure 1
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  		Figure 1. Flowchart explaining the literature search results

 

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  		Table 1. Reasons for the exclusion of sixteen studies during the abstract analysis phase
 
A systematic review of thirteen clinical studies with a follow-up of at least six months that compared sonic/ultrasonic scalers and manual instruments showed similar results for effectiveness in both treatments.8 The authors also concluded that the treatment with sonic/ultrasonic scalers demanded less time than the treatment with manual instruments. From sixteen assessed topics in the QUOROM statement, only one obtained grade C and another one was classified as B (Table 2Go).


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  		Table 2. Quality assessment of the systematic review using a letter grade scale
 
There were differences between the inclusion of articles by the systematic review (SR)8 and by this study. Three articles were identified in both SR and this study, but they did not meet this study’s inclusion criteria: one had different outcome measures,9 another had only three months control,10 and the remaining one used a nonconventional scaler tip.11 Therefore, they were excluded from final analysis. The other ten studies identified in the SR were not retrieved in our literature search.

The other selected study (RCT) used a split-mouth design to compare ultrasonic and manual instruments.12 Again, the efficiency of both therapies was not statistically different. The quality of this study is shown on Table 3Go with the CONSORT statement as reference. A greater number of topics were classified as B and C in this RCT than in the SR.


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  		Table 3. Quality assessment of the randomized controlled trial using a letter grade scale
 
No subject heading for the word "sonic" was identified. Therefore, the search for evidence was performed only with the word "periodontitis" in the "not exploded" search option. This search retrieved 10,554 articles.


   Discussion
Top
 Abstract
 Material and Methods
 Results
 Discussion
References
 
Several models that apply the concepts of evidence-based dentistry into clinical practice have been described in the literature.13–15 However, to the best of our knowledge, this study is the first to demonstrate a practical use of the CONSORT and QUOROM checklists to quantitatively assess the quality of selected studies. In this study, a periodontics case was used to demonstrate application of checklist-driven critical appraisal, but this systematic method can be applied to other fields of clinical dentistry.

The CONSORT and QUOROM statements were developed to help clinical practitioners critically appraise the characteristics of clinical studies. They are important tools for the practice of EBD.16 Our study attempted to show busy clinicians how to apply both guidelines in a systematic and practical way to interpret research evidence in a short period of time. By comparing the sections of the selected manuscripts to the checklists in a tabular format, clinicians can objectively evaluate each section of studies by grades (A, B, or C). This process can therefore provide a valuable guidance for dentists to systematically extract useful information from SR and RCT and evaluate the validity and quality of the extracted information. Consequently, more clinical decisions can be made based on research evidence.

The search strategy of this model used only three combinations of free-text terms linked by search operators, and it retrieved a great number of relevant articles in a short time span. When some free-text terms ("periodontitis" and "sonic") were used in the controlled vocabulary search strategy, it was only possible to obtain articles with one word ("periodontitis") and with a high number of articles not related to the searched topic. In fact, the controlled vocabulary search was too sensitive, and results generated were impractical to be applied into clinical setting. Therefore, the search strategy using free terms demonstrated a balance between sensitivity and specificity,17 and it retrieved a more realistic number of articles to be assessed by the clinician (Figure 1Go). This may be an alternative for busy dental practitioners.

The use of RCT and SR in this study provided more reliable results, as these studies are less prone to various biases and have been considered the best evidence for clinical decision making.18,19 Six months follow-up was an arbitrarily chosen threshold for the inclusion of studies in the search strategy due to the concern that a shorter period probably would not be sufficient for the comparison of effectiveness and efficiency between the two therapies.

The RCT had clearly more B and C grades than the systematic review when compared with the checklists. Following the proposed hierarchy of evidence,20 when more than one study is selected and there are different results, decision making should be based on the study with the best methodological quality. In our study, based on checklist references, the systematic review of RCT seems to have a better quality than the RCT.

Our approach in this study can be a practical model for the development and enhancement of evidence assessment skills, and it can be incorporated into an organized continuing education program. A potential limitation of the presented model is that, to correctly evaluate the evidence, clinicians need to have some experience with literature search and have an adequate understanding of the published guidelines. Therefore, it would be helpful if dental organizations such as local dental associations and dental schools could provide some training courses, for example, on study designs and basic statistics for general dentists. This could facilitate the implementation of EBD models described in this study or others into the clinical practice.

The chosen electronic database in this study was the PubMed/Medline. However, other databases could also be used to perform the literature searching process. It is important to note that each database has its own searching techniques, and therefore, the search strategy should be adjusted to the database used by the clinician.17

In summary, this study demonstrated an approach that translates scientific evidence from research directly into clinical dental setting. This process may help busy dental practitioners make proper clinical decisions.


   Footnotes
 
Dr. Faggion is a Private Practitioner in Florianópolis, Brazil; and Dr. Tu is Senior Clinical Research Fellow, Leeds Dental Institute and Biostatistics Unit, Centre for Epidemiology and Biostatistics, University of Leeds. Direct correspondence and requests for reprints to Dr. Clóvis Mariano Faggion, Jr., Rua Duarte Schutel, 181 Ap. 811,, 88015-640 Florianópolis,, polis, Brazil; ; 55-48-3211-8788 phone; 55-48-3222-2277 fax; clovisfaggion{at}yahoo.com.

The second author was funded by the United Kingdom government’s Higher Education Funding Council for England (HEFCE). There was no external source of funding for this study.


   REFERENCES
Top
 Abstract
 Material and Methods
 Results
 Discussion
 References
 

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