Home' News Bulletin : ADA News Bulletin August 2015 Contents 39
Practising evidence-based dentistry
WHERE DO WE START?
Today the buzz is evidence-based practice -- but what does it
mean and how can we achieve it in day-to-day dental practice?
We are all familiar with the old adage "The art and science of
dentistry", but which is more important -- the art or the science?
Debunking the myths about sound decision-making in dental
practice is often difficult. Busy practitioners are bombarded with
information relating to some areas of practice and in other areas
there is nothing more than "that's the way we've always done it"!
So how should we approach the clinical decisions that we need
to make every day -- whether they are related to the procedures
or product choices?
When developing guidelines for clinical practice in healthcare,
the ultimate aim must be that they lead to the desired patient
Let's take caries prevention as an example. Obviously the desired
outcome is keeping our patients cavity-free but for each choice
and recommendation we make -- what are we hoping to achieve?
There are many facets to this answer but ultimately, we want
to engage the patient and support them in maintaining good
oral health. We can assist patients in several ways -- optimising
their ability to perform good oral hygiene practices at home,
encouraging them to consume a healthy diet and ensuring that
they have access to effective preventive oral care products.
With regard to product choices -- how do we know which
information is most trustworthy? To answer this question we
need to understand the process of testing that new products
and technologies undergo:
Laboratory studies -- A series of different trials undertaken to
ensure safety and efficacy in a simulated environment. These in
vitro studies give an initial indication of whether a product should
be further developed for clinical testing. These studies should not
be relied upon for evidence of clinical efficacy because real life
conditions cannot be accurately simulated in a laboratory.
In situ studies -- These are usually the next stage of testing and
often utilise bovine or human tooth substance from extracted
teeth and in the case of caries preventive product may utilise an
artificial caries or demineralisation model. Whilst these studies are
useful in assessing whether the product shows any promise in an
oral environment, we must consider the substrate used (bovine or
human enamel) and the artificial lesion that was created prior to
testing in the oral environment. Ten Cate2 alerts us to the fact that
the predictive value of an in situ model with respect to a caries
preventive therapy is dependent on how closely the model relates
to the natural oral condition. Factors such as site of placement
of the enamel slabs within the mouth, duration of wear of the
appliance and whether the appliance is worn whilst eating and
drinking and during routine oral hygiene procedures will obviously
all have an important bearing on the outcome of the study.
Clinical trials -- When products show promise at these first two
levels of trial, they are then ready for clinical testing using the final
product formulation, in a target population, in the way it would
be expected to be recommended for use. The optimum type of
clinical study is the randomised controlled trial which randomly
assigns participants to test, placebo and/or control groups and in
which both the participants and clinical assessors are blinded to
which group the participant belongs to. Randomised controlled
trials are widely accepted as the best evidence to answer questions
about the effectiveness of treatments1 and are the best type of
study to rely on when making evidence-based clinical decisions.
Systematic reviews, meta-analyses and Cochrane reviews
-- once there have been several well-conducted randomised
controlled trials, a systematic review with meta-analysis can be
conducted and will provide the highest level of evidence of clinical
efficacy. An important step in this process is to pose a clinical
question that is specific and not too broad in scope.
Unfortunately, there are situations where randomised controlled trials
are not available or are few in number. When this is the case, lower
grades of evidence are sometimes used to develop guidelines. Case
reports and clinical trials using very small numbers of participants
provide the lowest level of evidence. It is tempting to use anecdotal
evidence from expert clinicians to formulate clinical recommendations
or guidelines but the weakness is that this type of evidence may
have many uncontrolled factors leading to the perceived success
of the product or procedure. For example, the expert clinician
may carry out intensive oral hygiene instruction and monitoring in
addition to the proposed intervention, the patient population may be
largely from one geographic or socio-economic group, the patients
may or may not have access to other interventions such as water
fluoridation, fluoride toothpaste and/or other preventive products.
Failure to recognise these confounding factors can lead to misguided
recommendations for the general population and so published
guidelines should always inform clinicians on the quality of the
underlying evidence for each recommendation.3
It is important also to look at where the research is published.
Reputable journals with good impact factors and where articles
are peer-reviewed prior to publication, are the most reliable source
of high quality studies. However, it is important to make sure
that the research is derived from a full research article and not an
abstract from a conference presentation. An example of this is the
Journal of Dental Research which, although it has a high impact
factor, publishes the abstracts from the International Association of
Dental Research meetings from around the world. These abstracts
represent a summary of the oral and poster presentations at the
conferences but the content of the abstract has not undergone a
peer review prior to being published in the journal and may even
be documenting a pilot study or preliminary results. This type of
reference can usually be identified as it will only be one page and
is often contained in a special issue of the journal. The obvious
disadvantage of using this type of reference as evidence for the
recommendation of a product or procedure is that the methods
and full data of the study are not able to be independently
scrutinised in order to decide upon the quality of the evidence.
Of course, when recommending preventive products or procedures
to patients several other considerations must also be made --
including caries risk, age of the patient, efficacy, affordability and
patient acceptance of the product. This is sometimes where the
"art" comes in and we need to alter clinical guidelines to suit
our individual patients. However, in order to make appropriate
guidelines and recommendations for the general population it is
important to use techniques, procedures and products that have
a sound evidence base wherever available.
In striving to make evidence-based decisions in your practice --
useful resources can be found at:
Cochrane Library (via Australian Dental Association National
Centre for Evidence-based Dentistry -- American Dental Association
Dr Sarah Raphael
Paediatric Dentist and Consultant Colgate Oral Care
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