To question the current widely used phrase, "evidence-based
dentistry" is similar to questioning the Bible in a meeting with
a devoutly religious group. However, in our candid opinion, we
clinicians need to express our concern about the obvious respect
for and overuse of this phrase and the unquestioning attitude of
many dentists and authors toward it. More importantly, we need
to open discussion about how evidence-based dentistry (EBD)
influences our patients, third-party payers, dental education and
ourselves. This school of thought is certain to spark some
debate; our intention is to provoke serious thought and discussion
on the following topic.
The purpose of this article is to help you to determine if,
when and how "evidence-based" research projects can help your
practice and your patients, and how to evaluate projects
reported in publications.
What is Evidence-based Dentistry?
Throughout the past few years, clinical dental practitioners
have heard and read the phrase "evidence-based dentistry" ad
nauseum. Almost every article, dental faculty member, research
paper, dental continuing education speaker and even lay publications
have picked up and used this popular "buzz" phrase. If
you were to observe the overall health science literature, you
would find hundreds of articles (with which we will not bore
you) proclaiming the advent and value of EBD and evidence-based
medicine (EBM) in dental, medical, nursing and allied
health science literature. However, there are a growing number
of articles discussing the limitations of it, especially in medical
literature. It is as if we have never had any evidence related to
our practice procedures in the past; that we just bumbled on
blindly. Because of the predominance and constant bombardment
of the phrase "evidence-based dentistry" used by dental
teachers, manufacturers and researchers, practitioners are wary
of almost any dental paper that is published. All of us see
research projects contradict each other in "evidence-based,"
"peer-reviewed" dental literature; some even in the same issue of
a given journal. Additionally, it is not uncommon to see a so-called
"evidence-based" publication offer results that are diametrically
opposed to the long-time observations of experienced
Is the phrase, "evidence-based dentistry" something new, a
passing fad, an academic fetish or is it something to which we
practitioners should pay strict attention to and use when making
decisions regarding patient care? Are there limitations to evidence-
based dentistry, and if so, what are they?
Evidence-based medicine is not new. In fact, David L. Sackett,
MD, one of the leading physicians involved with analyzing and
critiquing EBM in recent years says, "Evidence-based medicine,
whose philosophical origins extend back to mid-19th century
Paris and earlier, remains a hot topic for clinicians, public health
practitioners, purchasers, planners and the public." He states further,
"Criticism has ranged from evidence-based medicine being
old hat to it being a dangerous innovation, perpetrated by the
arrogant to serve cost cutters and suppress clinical freedom."1
How is EBD or EBM defined? Evidence-based practice (the
term that is replacing the use of EBM/EBD) is "the integration
of clinical expertise, patient values and the conscientious, explicit
and judicious use of current best evidence in making decisions
about the care of individual patients to improve clinical and
functional treatment outcomes.”1,2 In other words, we can conclude
that it is not just scientific evidence. It includes clinical
expertise. Often this aspect of evidence-based dentistry is overlooked
in lectures and publications.
Many dentists are familiar with the "hierarchy of evidence"
in research, which describes levels of evidence that are superior
or more accurate than lower echelon levels. These evidence levels are commonly positioned or ranked based on the degree of bias
or freedom of bias involved in the research methodology used.
Most publications and organizations rank the levels of evidence
from highest to lowest as follows:
What is the "best evidence"? The following definitions are
self-explanatory.3 The highest level of evidence is further
explained by the following three categories.
- meta-analysis and systematic reviews
- randomized controlled clinical trials
- prospective cohort studies
- case control studies
- case series and reports
- observations, expert opinions and editorials
- unpublished clinical data and observations of which clinicians are all a part
Meta-analysis: A review in which the results of many randomized
controlled trials are pooled and the overall results are
analyzed. We routinely observe meta-analyses in our work. The
significant problem with these compilations of data is that there
are usually supporting papers both on the positive and negative
side of any question, and you still have to come to your own
conclusions. As an example, the Cochrane Collaboration is a
widely used and quoted database of systematic reviews of randomized
controlled clinical trials. In this system, outcomes of
treatment are categorized as "likely to be beneficial," "likely to
be harmful," or "evidence did not support either benefit or
harm." This categorization is useful when a large amount of data
exists and is included in the review. However, the actual number
of randomized controlled clinical trials included is often small,
and direction for the dentists in treating their patients is questionable.
We often need more than just "likely to be beneficial"
to come to our own conclusions. El Dib stated in a 2007
analysis of 1016 systematic reviews from the 50 Cochrane
Collaboration Review Groups that 96 percent of the reviews recommend
further research.4 It has almost become a mandatory
requirement to end any article with the phrase, "however, further
research is required." What do practicing clinicians do in the
interim until the "best evidence" can be provided? Do we ignore
the other levels of evidence or our individual clinical expertise?
Randomized, double-blind controlled clinical trials: In a
randomized, double-blind trial, neither the investigators nor the
study participants know who is receiving whatever is being studied
versus the control for the study.
Randomized, controlled clinical trials: Same as above, but
Our following critique is provided to guide you in making
clinical decisions in treating your patients, and it is not intended
to be overly critical of dental research.
What if only one randomized, properly designed controlled
trial is reported in an article
you are reading?
Can you trust the results? The results of one study could be
purely a chance happening, in spite of a reported sophisticated
statistical analysis on the data the investigators have obtained.
Before making any decision about the value of a study, evaluate
the following conditions:
It is extremely difficult to analyze studies. We can name
numerous studies in the literature that have had one or more of
the preceding challenges, thus confounding the results. In fact,
many of these studies have been published in some of the most
respected peer-reviewed journals in the dental industry.
- Do you know and trust the investigators/authors?
- Is the article featured in a trusted journal?
- What group, company, manufacturer, third-party payer or
individual funded the study? There are often ulterior
motive potentials for publications. Many negative
research results are not published due to financial contracts
with the manufacturers or manufacturer-funded
"third-party" evaluation groups.
- Is the research truly blind?
- Does it appear that the funding parties for the research
could be biased from a financial standpoint?
- Are the investigators actually practicing what they are
studying? There are many authors who publish frequently,
but rarely or never pick up a handpiece.
- Was the protocol aligned with real-world practice standards
Determining whether the peer reviewers are competent
and non-biased can be another challenge. In our opinion, peer
reviewers are only sometimes competent and non-biased. We
can cite numerous published studies in which the peer
reviewers (who we were acquainted with) did not, in our
opinion, have significant real-world clinical background in
the subjects they were reviewing. Yet, the papers were published
in well-known respected journals, misleading the readers
and often providing significant income to the companies
involved in the study.
What if a well-designed controlled clinical trial was
It is obvious that if the group being studied does not represent
the broad population, the results will be biased toward that
group and only be representative of the characteristics of the
group being studied. As examples, a study of dentures made by
American Board Certified prosthodontic specialists does not
represent the results to be expected from the total population of
all dentists of various educational levels and experience. A study
of dental caries in one state or country represents only that area
and not a broader area. A Class II resin-based composite study
accomplished by one excellent clinician does not represent the
results to be expected from the broad population of dentists of
all abilities. Almost every journal you pick up has studies in
which whatever is being studied does not represent the true
practice of dentistry. The studies are easily identified. Look for
them, and accept them only for whatever specific population
What if a study has been done in-vitro only, without a
In our opinion, there are far too many studies in the literature
of this nature. There must be a clinical component to an invitro
study for any legitimate clinical conclusions to be made.
What about a single well-designed case-control or
A cohort or longitudinal study is where subjects are prospectively
followed over time without any intervention. A case control
study is where a group of patients and a group of control
patients are identified and information about them is determined
We just finished looking at such studies relative to the
longevity of amalgam and resin-based composite restorations
over time. The results were so variable that only a few questionable
conclusions could be made. On the other hand, such studies,
which are considered to be of a lower level than the previous
ones, are still useful if the groups represent real-world situations,
and are accomplished carefully.
Can you trust evidence from literature reviews or single
descriptive or qualitative studies?
Many authors review the literature to determine answers to
clinical or basic science questions. The reviews might be minimal
in scope or broad and detailed. The results could easily be based
on chance findings or the biases and opinions of the author(s).
Single descriptive studies are interesting and often provide
ideas and potentially useful information. Their results must be
scrutinized to determine their value.
How about the reliability of "expert" opinions from
authorities or expert committees?
In dentistry we constantly see these types of articles both in
respected journals and in commercial magazines. Often, the
people writing or speaking are true authorities who have broad
knowledge of available research as well as clinical experience.
Such trusted individuals have taken the time and made the
effort to analyze the available information on a subject and make
personal conclusions on the subject. The value of such opinions
must be based on the reputation of the person providing the
information, and past experiences relative to that person being
able to make conclusions based on both research and his or her
Conversely, opinions of persons not based on the available
information in the literature which express only personal opinions
must be scrutinized to determine their value. Many "experts" or
"key opinion leaders" have financial ties to the manufacturers of
the products or techniques about which they publish or on which
they speak. It is important to recognize those that are broad based
in their expert opinions and equally assess all products, treatments
and the research item being investigated.
Where are we? Can we trust anything?
Let's go back to Sackett's statements on the subject, which, in
our opinion, are profound. He states "EBM is the conscientious,
explicit and judicious use of current best evidence in making decisions
about individual patients. The practice of EBM means integrating
individual clinical experience with the best available clinical
evidence from systematic research." This is right on. Evidence comes
from many sources and it must contain two components: evidence
from systematic research and evidence from individual clinical
experience. Neither one by itself is enough!
Another definition of EBD that is in line with our own
thinking is "Evidence-based dentistry is the practice of dentistry
that integrates the best available evidence with clinical experience
and patient preference in making clinical decisions."5
Another frustrating and growing use of "evidence-based
Many insurance companies are moving toward "evidence-based
reimbursement" in which they will not pay for treatment
unless it can be proven by the highest levels of evidence. The
medical industry has witnessed lawsuits against this practice, yet
it still continues to be pursued. This growing trend is not only
questionable, but limits new and improved treatments for
patients. One technique exception is the growing number of
insurance companies that are covering implant restorations in
place of fixed partial dentures (bridges). Many more years will
pass before the strongest level of evidence will be available on
Where can clinicians find the "best evidence"?
We know that practitioners have very little time to look up
information and analyze multiple projects for their clinical
value. However, from time to time you might want to look up a
question which is bothering you. We have listed a few locations
below for you to find answers. Use these locations to find scientific
This statement gives clinicians guidance based upon many levels
of research and advises the clinician to "follow" the literature
for those improvements in treatment or higher levels of evidence.6
- PubMed www.pubmed.com
- Embase www.embase.com
- MEDLINE www.medscape.com
- Cochrane Collaboration www.cochrane.org
- Google Scholar www.scholar.google.com
- Peer-reviewed journals
- Professional associations that publish guidelines when not
all of the highest levels of research are available.
- A recent example, The Academy of Osseointegration recognized
that not all of the evidence is yet available, and
they published useful guidelines for specialists and general
dentists. Their 2010 Guidelines of the Academy of
Osseointegration for the Provision of Dental Implants
and Associated Patient Care states,
…the Council (ADA) recognizes that evidence-based
care requires the judicious use of current best evidence. It
is nonetheless recognized that much of the current evidence
base lacks consensus and, to this end, implant dentistry is
often practiced on the basis of best anecdotal evidence, which may or may not be supported by lower echelon studies
and/or case reports. As such, there is a responsibility for
individual clinicians to avail themselves of the parameters
for patient care for the safe and effective provision of dental
implants and to continue to avail themselves of ongoing
- Independent research groups.
- Our own nonprofit group, Clinicians Report (CR) (Previously CRA), has for 35 years conducted controlled
clinical trials, blended them with the trials of other
groups, determined practitioner experiences and opinions
on the subjects being studied, and made conclusions
and suggestions for implementation into practice. All CR research and the subsequent publications have contributions
from experts in their area, including all the specialties
and representing both academic and practitioner
orientation. CR implements a vigorous review process to
ensure that the information is accurate, timely and representative
of the majority of practicing dentists. The CR conclusions are based on the best scientific research available
and the clinical information and opinions obtained
from hundreds of experienced full-time practicing
Clinicians Report Evaluators. The information is published
Conclusions on "Evidence-based Dentistry"
- It is fortunate that we now have the concept "evidence-based
dentistry" re-identified. However, it is not new. It
is only a logical system to assist us in identifying current
truth for implementation into practice.
- The phrase evidence-based dentistry is greatly overused, misunderstood
by many and perhaps too trusted by the profession.
- Projects that claim to be evidence-based can be and often
are flawed, and the research needs your personal evaluation
and comparison with your own clinical observations to
determine the usefulness of the information.
- Basing your clinical decisions on just the "best scientific
evidence" does not provide complete answers to questions.
Clinical observations must be considered also.
- Often there are multiple "correct" treatments or solutions to
our patients' needs that are equal in level of evidence.
Infrequently is there only one treatment for a specific condition.
- Published articles must be scrutinized on many levels to
determine their value for practicing dentists.
- There is "scientific evidence" on both the positive and the
negative side of almost every clinical question.
- After observing the best scientific evidence available, clinicians
should blend the scientific information with their
own and their peers' clinical observations and experiences
and finally make clinical conclusions.
- Whatever is considered truth (fact) today will probably be
questioned or disproven tomorrow.
- Evidence-based dentistry concepts are only a guide. They
are not inviolate and they must be observed with caution.
- Dentists are smart people. They can usually determine
truth from hype on any clinical question. Such decisions
come with careful analysis and time.
- Sackett DL, Rosenberg MC, Gray JAM, Haynes RB, Richardson WS. Evidence based medicine: what it is
and what it isn't. BMJ 1996; 312:71.
- Committee on Quality of Health Care in America. Crossing the Quality Chasm: A New Health System for
the 21st Century. National Academies Press.
- Melnyk BM. Fineout-Overholt E. Evidence-based practice in nursing and healthcare: A guide to best practice.
Philadelphia: Lippincott, Williams & Wilkins.
- El Dib RP, Atallah AN, Andriolo RB (August 2007). "Mapping the Cochrane evidence for decision making
in health care". J EvalClinPract 13 (4): 689–92. doi:10.1111/j.1365 2753.2007.00886.x.PMID
- Healey D, Lyons K. Evidence-based practice in dentistry. NZ Dent J. 2020 Jun; 98(432):32-5.
- Guidelines of the Academy of Osseointegration for the Provision of Dental Implants and Associated Patient
Care. Int J Oral Maxillofac Implants 2010;25:620-627.