Evidence-Based Dentistry: A Developing Paradigm

Headnote

Abstract

Now a days the practice of dentistry is becoming more complex because of continually changing materials and methods, avai- lability of enormous research literature, information explosion and its dissemination through advances in internet, and an incr- ease in awareness and expectations of patients. Though research evidence can now be readily accessed by both patients and de- ntists, it is becoming a challenge to filter out the relevant and valid research findings from the abundant research literature ava- ilable and apply it in the clinical management of patients in everyday practice. The principles and methods of evidence-based he- althcare give the dentists an opportunity to integrate the research into clinical practice. To practice in an evidence-dased dentistry manner, practitioners must be able to formulate a clear question, find the best available evidence efficiently, evaluate the eviden- ce systematically and, if it is relevant and credible, apply the results of the appraisal to their practice. The evidence-based app- roach has spread from university and epidemiology origins into virtually every aspect of dental research and the delivery of care.

Keywords: Evidence-based dentistry; research design; systematic reviews; meta-analysis.

Introduction

In the recent years, the world of dentistry has been inun- dated with numerous new materials, clinical techniques and methods. The advances in internet and the information explosion have made these developments accessible to bo- th the patient and the dentist. The patients now are more ed- ucated, have increased expectations and demand for assur- ance of effectiveness of the treatment. The knowledge base in dentistry has also evolved from anecdotal evidence bas- ed on experiences of experts towards scientific literature based on research. The amount of research now is overwh- elming. Despite increased desire of the dentists to remain updated with the recent developments and to base their cli- nical decisions on the best research evidence, it is challen- ging for them to filter out the valid and relevant research fi- ndings from the huge body of research literature available today. Because of the variation in the quality of research re- ports and accuracy of conclusions drawn, tools are needed to scientifically interpret and apply the research findings.

Following evidence-based approach can help provide a so- lution to these problems as it is aimed at integrating the re- search into real world clinical practice so as to assure quali- ty care to patients and to justify clinical decisions.14 Recent years have seen an increase in the importance of evidence- based approach in education, planning research and prac- tice in all healthcare disciplines.

Evidence Based Dentistry

Evidence-based medicine has been defined by Sackett et al., as the conscientious, expedient and judicious use of cu- rrent best evidence in making decisions about the care of individual patients.145 The American Dental Association (ADA) has defined Evidence-Based Dentistry (EBD) as an approach to oral health care that requires the judicious inte- gration of systematic assessments of clinically relevant sci- entific evidence, relating to the patient's oral and medical condition and history, with the dentist's clinical expertise and the patient's treatment needs and preference.6 Underst- anding the principles and the method of evidence-based dentistry can help dentists to interpret and apply research findings in making clinical decisions and hence, better care of their patients.1

The term evidence-based healthcare is sometimes used to describe the application of evidence-based approaches at the population level.5

Evolution of the dental knowledge base and the concept of Evidence based dentistry

The scientific research evidence has built the knowledge base in dentistry and has always provided the foundation for quality practice. The concept of using current evidence to guide decision making was first introduced by Gordon- Guyatt and the Evidence based working group at Me Mas- ter University in Ontario, Canada in 1990's.7 The develop- ment of the concept of evidence-based dentistry can be tra- ced to the revolutionary changes that have taken place over the years in the way the knowledge is produced and disse- minated.58

In the early years of dentistry, the knowledge was more or less based on experience of experts. There was limited sha- ring of the knowledge amongst practitioners and it was mo- stly passed on by experts to the novices with virtually no or limited texts available. Around the middle of the 18 th centu- ry, the texts based on observation of experts began to get published, exemplified by Fauchard. The knowledge diss- emination improved with the establishment of dental scho- ols and 1st dental society journals in the 1840's. It was at the beginning ofthe 20th century, that protocol based experime- ntation became more common. The product of this evolu- tion was the traditional review of literature based on a sub- jective interpretation of literature by experts. This phase marked the most active period of knowledge disseminati- on, growth of university based dental curriculum, and prol- iferation of journals.5 910

The dental knowledge base has now entered a new era- 'The Age of evidence'. Knowledge creation in this era is characterized by the dominance of randomized controlled trials and improved statistical methods. In the publications, the systematic reviews have replaced traditional reviews. Systematic reviews represent a substantial change in the knowledge synthesis through ensuring inclusion of relevant evidence, de-emphasizing the role of expert, and minimizing bias through strict protocols and objective approach. The methods of knowledge diffusion now include university curriculum, text books, journals, and continued dental education. Evidence based clinical guidelines are being propagated by various agencies, and evidence summaries or abstracts of systematic reviews are also published commonly in dental journals. The most significant change in the dissemination of dental knowledge base is easy access by both patient and dentist to the substantial majority of the knowledge base through the internet.10 All of these developments indicate an increasing emphasis on evidence for guiding clinical practice and hence the increased focus on EBD by dental organizations worldwide.11

Application of Evidence-Based Dentistry

It involves 5 steps:1'2'5'12

1. Framing a clear and focused question from a clinical problem

2. Searching for the best evidence

3. Reviewing and critically appraising the evidence

4. Applying the results of the evidence to patient care in consideration for the patient's preferences, values and circumstances

5. Evaluation of performance of the technique, procedure or material

1. Framing a clear and focused question

Everyday we come across patients with unique problems. Articulating the clinical problem in the form of a question facilitates the process of search of evidence. Practitioners of EBD use a framework called PICO Model to form a focussed question. It includes identifying the Patient or Population; Intervention; the Comparison; and the specific Outcome.2 5 Example: In adult patients with sleep bruxism, does the use of occlusal splint, as compared to no intervention, reduce the temporomandibular pain? A clear question helps to identify key words for an effective search strategy. The focus will make it easier to limit the electronic search and to discard the research that is not pertinent.

2. Searching for the best evidence

This requires an understanding of the 'Evidence-Hierarchy' or the 'Levels of evidence' and the basic concept of clinical research design (Figure 1 ).15 For questions related to inter- ventions or therapy, systematic reviews and randomized controlled trials represent the highest levels of evidence, whereas case reports and expert opinion are the lowest.14 For questions related to diagnosis, prognosis or causation, other study designs such as cohort studies or case-control studies are more appropriate. Randomized controlled trial (RCT) is the strongest research design because this has the greatest potential to minimize bias through features such as randomization which keeps study groups as similar as pos- sible from the outset, blinding, appropriate outcome meas- ures and statistical analysis. Randomized controlled trials are followed by observational studies, the case control stu- dies and the case series in declining order of strength.5

Systematic Reviews- When the information from all rele- vant randomized controlled trials addressing the same question is combined using a strict protocol, rigorous met- hodology, the result is a systematic review or overview. Sy- stematic reviews, also called as "secondary" publications or integrative research is generally regarded as the best for- m of evidence because these report the combined results of a number of primary studies. The methodology includes a comprehensive search of all potentially relevant articles and the use of explicit, reproducible criteria in the selection of articles for review.4 The primary research designs and st- udy characteristics are then appraised and the results are interpreted. The findings from individual studies can then be aggregated to produce a summary estimate of the over- all effect of the intervention. A quantitative systematic rev- iew, or meta-analysis, is a systematic review that uses sta- tistical methods to combine the results of 2 or more studies. Meta-analysis is performed when the studies are similar enough so that combining their results is meaningful.15 Ho- wever, it is necessary to exercise caution in interpreting the results, a meta analysis is only as good as the studies it co- mbines.5 It can be valid only if the studies included repre- sent the complete body of research and are not biased in such a way that conclusions misrepresent the effectiveness and safety of clinical interventions.16

Sources of evidence-Anumber of excellent and highly sp- ecialized databases provide electronic access to original re- search. MEDLINE, a popular multipurpose database, crea- ted and maintained by the United States National Library of Medicine (NLM) of the National Institutes of Health is an index to the biomedical literature from 1950 onward.1718 Medline can be accessed through gateways such as Emb- ase and PubMed. Using certain strategic search skills can help us extract relevant evidence from PubMed.18 A clearly defined patient group and intervention are the major conce- pts inmost subject searches. Other search strategies inclu- de using features such as 'Exploding' and Boolean operat- ors. The study design, language, and date can be used as li- mits. A special feature of PubMed, the Clinical Queries mode, has been developed to assist in locating original stu- dies with high quality designs (such as randomized trials) suitable for EBD enquiries.8 Applying filters such as the ty- pe of question (diagnosis, therapy, etc) and the scope (bro- ad or narrow) is very useful in reducing the volume of ref- erences retrieved. The Clinical Queries mode can also be used to find systematic reviews that have been published in journal article form.

Secondary resources- Over the last 2 decades, evidence- based research groups working in a wide range of countries have produced a systematic and reliable evaluation of the evidence about a variety of topics. The reviews are condu- cted rigorously according to recommended guidelines, by expert teams using extensive information resources and se- arch strategies.8 A critical summary is a short summary or abstract of a systematic review and is an efficient means of providing a rapid oversight ofthe systematic reviews to the clinician. Clinical recommendations or guidelines are syst- ematically developed statements for patient treatment ma- de by an expert panel based on the best evidence available. There are several forums and internet sites available now to facilitate the evidence-based dentistry which disseminate the systematic reviews, critical summaries and clinical pra- ctice guidelines.8 ''These include the sites produced by aca- demic centres, including university and hospital sites, prof- essional organization sites and sites of several medical sea- rch engines.

One the major sources of reliable evaluated information is Cochrane Database of Systematic Reviews (CDSR), a sec- tion of the Cochrane Library available at http://www. cochrane.org. ADA has also established Centre for Evide- nce Based Dentistry to disseminate summaries of systema- tic reviews and evidence-based guidelines. Many journals now publish systematic reviews; examples include Evide- nce-Based Dentistry and the Journal of Evidence-based Dental Practice

3. Critical appraisal of evidence

Once one finds the studies that address the question, the ne- xt step is to decide if these are relevant to the clinical prob- lem and whether the results can be applied to one's patient. Assessing the validity (closeness to the truth) and the rele- vance (importance and usefulness) ofthe evidence is called critical appraisal.3 This would involve careful reading and analysis of the articles with respect to how the study was carried out (the methodology), what the results were, and whether the conclusions arrived at were reasonable.4 It inv- olves asking the following questions:'9

a) Study question- Did the study ask a clearly focused qu- estion in terms of population studied, the intervention giv- en and the outcomes considered?

b) Randomization- Were the patients randomized to the intervention and control groups by a method that ensured the assignment was random? Does the study explicitly des- cribe the allocation of patients to the intervention and con- trol groups?

c) Blinding- Were the patients and the clinicians kept blin- ded (masked) to which treatment was being given?

d) Sample size- Did the study have enough participants to minimize the play of chance

e) Follow-up- Were all patients in all groups followed up and data collected in the same way?

f) Interventions and co-interventions- Were the interve- ntions described in sufficient detail to be repeatable by oth- ers? Were the 2 groups cared for in a similar way except for the study intervention?

g) Result: Are the results of study valid? What were the re- sults? Were clinically important outcomes assessed?

h) Applicability- Will the results help me in caring for my patients? Are the study patients similar to my own?

4. Apply the evidence to the patient

Having found the evidence, it is time to apply it to the pat- ient. The evidence has to be integrated with clinical exper- tise and the patient's unique circumstances and preferences (Figure 2).

5. Evaluate how useful it was

This step serves as a feedback loop in which the effective- ness and efficiency of the process is determined. In other words, how much did the process help the patient and if not much, what could be done to improve it next time?4

Benefits of Evidence-Based Dentistry 1 2 921

1. The dentists are benefitted as it provides opportunity for improved clinical decision making and treatment planning based on stronger clinical scientific evidence. Adopting E BD helps in minimizing risks of harm and maximizing tre- atment safety. The treatment decisions are easier to justify, especially when there is a dento-legal issue. This would al- so counter the criticism of dentists because of findings that enormous variations exist in treatment recommendations and health care facilities.

2. Patient is benefitted as time and resources are saved by choosing treatments that are more effective and efficient.

3. It informs dental researchers and educators, thereby im- proving their insight and methods.

4. The compiled evidence can aid the government and the policy makers to decide on useful and cost effective oral health care policies.

Problems with Evidence-Based Dentistry2 14 22 23

1. Many dentists continue to practice the skills that they le- arnt in dental school; based on anecdotal evidence rather than true scientific evidence.

2. Some clinical trials where the size of experimental and control group is too small, risk an erroneous conclusion. The existence of publication bias is a big threat to evide- nce-based dentistry practice.

3. Other problems exist with finding the most recent evid- ence. Randomized controlled trials are expensive and diffi- cult to mn and the results take long to get published. There is need to focus efforts on high quality studies to reduce the number of unnecessary trials and to prioritize areas for sys- tematic reviewing.

Challenges and the future of the evidence-based dentis- try practice

The evidence based dentistry poses some particular challe- nges to the profession. They include resistance from denti- sts, misinformation about evidence-based practice, the thr- eat of the loss of clinical autonomy, inappropriate dental education, and dearth of evidence for much of dentistry. Its practice involves a set of skills that are different from the usual and so, will require a different approach to dental ed- ucation for the practitioners or through a revised dental sc- hool curriculum.1625 Despite its limitations, the profession is accommodating the evidence based dentistry and benef- itting from some of its early outcomes. For example, syste- matic reviews have helped resolve some clinical issues, while posing challenge to some of our general belief on ot- hers. The need for evidence, as shown in systematic revie- ws that failed to answer common clinical questions, has led to the initiation of research work so as to add research find- ings to the evidence base. Dental school curriculum are be- ing revised to include basic information on EBD concepts and to ensure that the course content is evidence based.31126 Dentistry has abundance of published research but there is still dearth of strong evidence in the form of unbiased ran- domized controlled trials on many issues.22 Under these cir- cumstances, identifying the best evidence and incorporati- ng it in daily clinical practice is challenging. However, on- ce the skills are learnt and there is sufficient evidence, evi- dence based science cannot only enable the clinicians to pr- ovide best treatment to individual patients, but can also su- pport prevention activities and improved patient care at co- mmunity level.27

Conclusions

The need for valid and current information for answering everyday clinical problems is growing. When considering a new therapeutic or preventive intervention, the highest levels of evidence, randomized controlled trials (RCTs) and systematic reviews, should be sought before subjecti- ng patients to possibly useless, and perhaps even harmful, treatments. Evidence based care is a global movement in all health science disciplines. The evidence-based appro- ach is helpful for efficiently filtering, from the knowledge base, what is truely important for clinical decision making. It also helps the researchers and educators identify the are- as where the knowledge or research is lacking and develo- ping critical thinking skills. EBD, however, is not a rigid method and cannot result in cookbook approach to individ- ual patient care. The best external evidence must be integr- ated with individual clinical expertise, experience and jud- gement; as well as the patient's clinical state, predicament and preferences. The evidence-based dentistry is a movem- ent that can improve both the quality of dental education as well as practice.

References

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