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Should
a non-carious cervical lesion be restored?
Some dentists recommend watchful-waiting.
Others recommend early intervention. No matter what you decide,
here’s some research you should know about ...
by Nelson Gendusa, DDS
Director - Research
It was just 12 years or so ago that Dr. John O. Grippo introduced
the word “abfraction” and his concept of the “abfraction
lesion” ... a cervical “erosive” lesion created by
the mechanisms of resultant stresses from occlusal loading.1
Until John showed us the way, we’d assumed that cervical lesions
were caused primarily by toothbrush abrasion or acidic drinks. In
fact, these factors probably DO contribute to lesion formation,
but stress concentration resulting in stress/fatigue-corrosion within
the tooth (the GRIPPO FACTOR) is now generally recognized as THE
primary determinant of the depth of the lesion.
John is careful to correct me when I refer to him as the discoverer
of the occlusal/cervical link. Others had studied it before him.*
However, John along with Professor James Masi of the School of Engineering
at Western New England college were the first to describe the complex
etiology of these lesions, where the loss of tooth substance caused
by stress in the presence of acids, can be further exacerbated by
toothbrush abrasion. 2
When a patient occludes on the linqual cusp, stress concentrates
smack at the deepest point of the lesion. (Think of it as the tooth
trying to “fold” over at the defect.) There’s less
stress out at the margins. As a result, tooth structure is destroyed
much faster at the deepest part of the lesion than at the margins.
The result is the V-shaped or notched cervical erosion called an
abfraction. It’s a vicious spiral. The deeper the defect gets
... the worse the stress at the bottom. So it deepens even more.
Which makes the stress at the bottom even worse, so ...
But wait, it gets worse.
When this stress concentration occurs in an acidic environment (plaque,
diet, reflux, etc) the rate of tooth destruction increases due to
a phenomenon called “stress-corrosion.” And if the force
loading the tooth isn’t constant, but cyclical (as it is during
mastication) the ditching is even further exacerbated. Here it’s
called “fatigue-corrosion.”
And now for the good news
New research suggests that if you intervene by placing a bonded
restoration, you can halt or at least slow the spiral. The stress
won’t be completely eliminated, but the distribution will change
so there’s much less concentration at the bottom of the lesion.3
As a result, the rapid progression will stop.
The restoration not only reduces the concentration of mechanical
stress, but also protects the vulnerable surfaces from the corrosive
environment and toothbrush abrasion. Prior to placing any restorations,
John recommends that you carefully evaluate the occlusion and the
other contributing factors. (He published an excellent summary of
these factors a few years ago in an article still available from
the ADA Library Services.)4
When we introduced Epic®-TMPT in 1993, we showed
the material being placed into a notch-shaped lesion in #20. (See
“1993” above) The “2002”, photo shows the same
tooth today. Notice the small non-carious abfraction that’s
developed in the enamel above the restoration. This shows that the
patient is still clenching, still creating stress. Yet the restoration
remains intact. The resilient Epic-TMPT stopped the rapid notching,
however the activity then occurred at the unprotected margin.
By the way, the same day that bicuspid was restored, an identical
Class V was bonded in the proximal molar using Amalgambond. Two
years ago, the MOD amalgam gave up the ghost, so the molar was crowned.
During tooth preparation, the 8-year-old Epic was removed. And the
dentist discovered a pristine restoration/tooth interface. No leakage.
No discoloration. It looked pretty much as it did the day the restoration
was placed.
And that, in a nutshell, is what a slightly resilient material and
a good bonding agent can mean when you’re restoring a cervical
lesion. By flexing with the tooth, the restoration remains bonded
- absorbing and redirecting much of the stress that might otherwise
be destroying tooth structure.
Dr. John Grippo lives in Longmeadow, MA. He is happy to answer
questions about cervical lesions - and is available for lectures.
His e-mail address is meadownet@aol.com.
1
Grippo JO. Abfractions: a new classification of hard tissue lesions
of teeth. J Esthet Dent. 1991 Jan-Feb;3(1):14-9.
2 Grippo JO, Masi JV. Role of Biodental engineering factors (BEF)
in the etiology of root caries. J Esthet Dent. 1991 Jan-Feb; 3(1):
14-19
3 Kuroe K, et al. Biomechanical effects of cervical lesions and
restoration on periodontally compromised teeth. Quint, Int. 32:2,
p111-118, Feb 2001
4 Grippo JO. Noncarious cervical lesions: The decision to ingnore
or restore. J Esthest Dent. 1992 (Supplement) Vol 4:55-64
5 Halvorson RH, et al. Cuspal microstrain comparisons of adhesive
bonded amalgam. J Dent Res, 74:Spec, Abstr 752, p 105, Mar 95
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