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6 | CERECDOCTORS.COM | QUARTER 3 | 2014
||| FASBINDER
uses statistical measures, including data
from multiple studies, to generate an
assessment on the predictability of a
clinical outcome.
A SYSTEMATIC REVIEW OF CAD/CAM
A clinician wishing to become knowl-
edgeable about CEREC restorations is
faced with this dilemma. Do they have to
review almost 30 years of clinical studies
themselves to find an answer? One
approach would be to locate a system-
atic review article. The most recent
systematic review on CAD/CAM resto-
rations was found by this author to be by
Wittneben and colleagues, and published
in 2009. The investigators performed a
search of the dental literature from 1985
to 2007 to identify 329 studies involving
CAD/CAM single-tooth restorations.
They were able to identify 16 articles,
including 14 prospective studies and two
retrospective studies, on 1,957 restora-
tions for further analysis. The restora-
tions had a mean clinical service time of
7.9 years, resulting in an overall five-year
survival rate of 91.6 percent. This was
calculated to be a 1.75 percent failure rate
per year per 100 restorations. This failure
rate may seem high for most current
CEREC clinicians, however this system-
atic review included only studies using
the CEREC 1 or CEREC 2 systems. And
this illustrates a common criticism of
EBD; it is generally not possible to find
systematic reviews on the newest mate-
rials and techniques since it takes time to
generate clinical studies.
Lack of evidence does notmean lack of
effectiveness. It means it is not possible
to advocate for a predictable outcome.
This is commonly the problem for
newer materials and techniques — a lack
of clinical studies to provide evidence of
a predictable outcome. And this poses a
problem for clinicians: if there is a lack
of scientific evidence, what should be
used to evaluate the effectiveness of a
material or procedure?
THE CLINICAL STUDY AS TOOL
So, where does that leave the thoughtful
clinician? A single clinical study or case
report is insufficient evidence on its own
to justify a clinical decision. However,
they can still be valuable tools. They
illustrate potential new approaches to
solving a clinical problem or provide a
description of an innovative treatment
technique. They also can reveal early
evidence on how well the newer mate-
rials or techniques may perform. The
most significant finding would be to
provide early evidence of poor perfor-
mance. Single clinical studies just do not
provide sufficient evidence of predict-
ability of the outcome. Replication of
the outcomes across a number of clin-
ical studies is the true test of clinical
predictability.
Review type articles of materials,
techniques or procedures attempt to
summarize the published evidence on
a topic. They do not reach the level
of evidence of a systematic review
primarily because there is consider-
ably less scientific evidence to report,
but the review does provide a useful
summary of what may be available
at that time, and can be better than a
single study to appreciate the area of
interest.
How do in vitro or laboratory studies
factor into “best evidence”? The search
for an in vitro test that is truly predictive
of clinical outcome has been fruitless
to date. That does not mean that they
provide no scientific evidence; labora-
tory studies are very useful to test theo-
ries for product development and rela-
tive performance. A good example of
this is the numerous adhesive bonding
studies that are published. They provide
valuable information on how newer
products may perform in specific
physical property tests; however they
just do not provide sufficient evidence
for predicting clinical outcomes. Only
controlled clinical studies can provide
Clinicians need
the best available
evidence, not just
any available
evidence. It is
not just selecting
studies that support
a particular point
of view, but also
studies with
opposing findings,
and attempting to
explain the different
outcomes. One of
the foundations
of a successful
dental practice is
predictable clinical
results for patient
treatment.