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Fasbinder has studied CAD/CAM restor-
ative modalities for more than 20 years,
and stands by the abilities of well-placed
all-ceramic restorations — both full- and
partial-coverage — to stand up against
the abuse they will be subjected to in the
mouth. As he and I talked about the effec-
tiveness of an onlay compared to a conven-
tional crown, I asked him if there were any
research or articles delineating the pros
and cons of onlays comparedwith conven-
tional full-coverage crowns. His response
was that “any evidence comparing onlays
versus crowns is purely anecdotal.”
4
As I tried to find more specific compari-
sons of crowns andonlays, the responsewas
always similar to “we have crown studies or
wehaveonlaystudies,butnothingtogether.”
Unfortunately, a research project needs
funding, and that fundingmost often comes
from dental manufacturers who want to
show
how
their
materials holdup compared
to other similar companies. They are not as
concerned if their product can be used just
as effectively in one situation compared to
another. Research endeavors can cost more
than $300,000 to facilitate. In order to tell
the dental community anything useful,
more than 75-100 restorations need to be
prepped, fabricated and seated by a compe-
tent teamor individual, and then six-month
recall appointments need to be in place
for follow-up and data collection for many
years thereafter. There is also the important
need of having control groups, and calcula-
tionof results, not tomention the time spent
putting all of those findings into a coherent
and usable format for the public. The cost
associated with such an undertaking is
prohibitive for most private entities and,
as such, a sponsor is needed. This need for
funding is also the very thing that can cause
the results achieved to be received with
speculation by the doctors meant to benefit
fromit.Theyseenothingmore thananother
advertising campaign touted by the very
peoplewho stand tobenefitmost fromtheir
positive outcomes. Dr. Fasbinder reminded
me that, “research isn’t conducted so that
only one person or group can get positive
outcomes; it’s about being able to have data
that benefits themasses.”
4
So, where can we turn for information
on how onlays stand up against crowns if
there isn’t any reliable research to support
our hypotheses? Many of us need look no
further than our own practices to find our
very own
anecdotal
answers. Dr. Chris-
tensen extrapolated that the vast majority
of onlay and other partial-coverage indirect
restorationsarecompletedbydentists inthe
CAD/CAMworld.Farandaway,thatismost
likely to be those reading this magazine;
CEREC owners who want to improve their
ability to face and fix the problems coming
through their doors. I was curious just how
many onlays
I
haddone in the last fewyears
(because in my mind, I was doing them all
the time), and Iwas shocked to see that only
4 percent to 5 percent of my indirect resto-
rations during the last two years, respec-
tively, were onlays. I have to admit that I am
among those of us who need to see the light
and better recognize that onlays are a viable
and often times superior (in conserving
tooth structure and serving the patient’s
needs) restoration when compared to full-
coverage crowns.
Although there isn’t any specific data
showing when an onlay could be better
suited to a situation than a crown, Dr. Chris-
tensen has tested the strengths of onlays
in his lab in Provo, Utah, and released the
results in his January
Clinicians Report
.
Amongthetestedteeth,wherenon-restored
teeth were the control group, and zirconia,
Lava Ultimate, Empress, and e.max CAD
were used for the onlays,
“all onlay mate-
rials were shown to have higher strength and
resist
cuspal fracture better than unrestored
natural tooth structure”
1
(Figs. 5-8).
Conclusion
Onlays are nothing new. We’ve all seen
them and know that they can be highly
successful and ought to be a great addition
to the armamentarium we use to treat the
broken-down dentition. Crowns also are a
fantastic aid that we use and will continue
to use for the foreseeable future. That said, I
feel duty bound tomy patients to offer them
the
opportunity
tokeepmoreof theirnatural
toothstructurewhenpossibleandtoprovide
more than a “one size fits all” approach to
treating a fractured or decayed tooth. The
CERECmachine and the CAD/CAMworld
in general have been so blatantly misbal-
anced toward the full-coverage
“
crown in
a day
”
mentality, not because it hasn’t been
able to attain great fits, but because we as
dentists have been unknowingly unwilling
to embrace anything else. Every one of us
has a typodont from Sirona with multiple
onlay preps that we could practice with,
but most of our practice has come from the
crown preps they provided. Take the time
to brushup onwhat you need to do tomake
onlays aviablepart of yourpracticebecause,
at the end of the day, The Golden Rule still
holds sway. You owe it to your patients.
For questions and more information,
Dr. Sutton can be reached at
.
references
1 Christensen, Gordon, “Are Tooth-Colored Onlays Vi-
able Alternatives to Crowns?” Clinicians Report.
Volume 5, (January 2012): Pages 1 and 3
2 Delta Dental. Third Party Insurer. September 25, 2012.
3 O’Brien, William. Director of Milwaukee VA and
Prosthedontist. 2004
4 Fasbinder, Dennis. Program Director of the Advanced
Education in General Dentistry Program at the Uni-
versity of Michigan. September 12, 2012
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7
8
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