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11/29/2010
1
Non-Carious Cervical Lesions:
Etiology and Considerations for
Successful Treatment
Dr. Harald O. Heymann
UNC School of Dentistry “It is the differences in the opinions of
good men that is knowledge in the
making”
-Goethe
A Current Popular Theory Being
Promulgated Maintains That Non-Carious
Cervical Lesions (NCCLs) are Exclusively the Result of
Toothbrush and Dentifrice AbrasionAbrahamson TC. The worn dentition: pathognomonic patterns of abrasion and erosion. Inter Dent
J. 2005; 55:268-276.Dzakovich JJ and Oslak RR. In vitro reproduction of noncarious cervical lesions. J Prosthet Dent; 2008; 100(1): 1-10.
Are non-carious cervical
lesions caused solely by
toothbrush/dentifrice
abrasion or do other etiologic factors exist? Non-Carious Cervical Lesions
The Question At Hand:
Is this NCCL solely the result
of Toothbrush/Dentifrice
Abrasion?
How often have you found
isolated NCCLs when
conducting an exam?
NO…. research and clinical
observation strongly
support the role of tooth
flexure and associated weakening of cervical tooth
structure as a strong
etiologic factor
This type of NCCL is called
an ABFRACTION
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Abfraction
Grippo J. Abfractions: A new classification of hard tissue
lesions of teeth. J Esthet Dent 1991; 3(1):14-19.
A term that means “breaking away.”
Proposed by John Grippo in 1991 to
describe non-carious cervical lesions
whose pathogenesis is largely related to stress induced tooth flexure.
Proposed Mechanism
Lee and Eakle,
J Prosthet Dent, 1984
52(3):374-380
“Possible Role of Tensile
Stress in the Etiology of
Cervical Erosive Lesions
of Teeth”
Early Theories
Tooth Flexure is Not
Theory, It is FACT!
Numerous finite element
analysis (FEA) studies
reveal tooth flexural
stresses are concentrated in the cervical region.
Image courtesy Dr. William Liebenberg
Why is the cervical
area of the tooth more
prone to weakening
and breakdown from tooth flexure?
Studies show that stress
concentrations occur in the
cervical region underocclusal loading (Goel and
Khera, 1990, Rees, 1998).
DEJ is poorly developed in
the cervical with little
scalloping (Spir, 1988).
Images courtesy Dr. W illiam Bartel
Why in the cervical? Enamel in cervical region is
largely aprismatic and enamel
crystals morphologically indistinct (Poole, et al, 1981).
Cervical enamel is more
brittle than occlusal enamel
and more subject to breakdown
(Hassan, et al, 1981).
Why in the cervical? Lambrechts, et al (1987) report findings of enamel cracks in the
cervical region under tensile stress.
Braem et al (1992) report SEM evidence of crack propagation.
Harnirattisai (1993) demonstrated SEM evidence of cervical
cracks extending 3 to 7 microns into dentin.
Since the perio ligament is only .3mm wide (Scott, 1982), tooth “bottoms out” in socket with occlusal loads that begin at less than
10N (Picton, 1964), resulting in cuspal deformation (Rees, 2000).
11/29/2010
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A bio-mechanical engineering concept
whose relationship to abfractions was
introduced by Grippo and Masi, 1991
Occurs when stresses (tooth flexure)
are concentrated in the presence of
corrosive agents (lowered pH at site)
Results in greater loss of tooth
structure contributing to formation of
NCCLs.
Stress Corrosion
• Dietary factors (acidic foods, drinks)
• Reduced salivary flow (lowered buffering capacity)
• In-situ factors (dental plaque)
Lowered Oral pH
• Parafunctional contacts (bruxism,
clenching, occlusal disharmony, etc.)
Tooth Flexure Conclusions Regarding Tooth Flexural Effects on Teeth:
Tooth flexure is fact, not theory.
Tooth flexure results in cervical stress concentrations.
Cervical tooth structure is structurally inferior.
Cervical tooth structure is more prone to weakening when
stressed, especially in an acidic environment (stress corrosion).
Weakened tooth structure from flexural stresses likely is more
prone to abrasion and chemical erosion.
"Research supports a complex etiology which is most often multifactorial
in nature"
Non-Carious Cervical Lesions:
The “Bottom Line”
Bader JD et al. Case-control study of non-carious cervical
lesions. Comm Dent Oral Epidemiol 1996; 24:286-291.
The Doubters Still Remain! Initiation vs. Progression
of Cervical Lesions
"What causes the initiation
of cervical lesions may or
may not be what results in
their progression"
Abfractions:
Clinical and Epidemiological Studies
and Evidence
Are NCCLs Really Due Solely to
Toothbrush/Dentifrice Abrasion? Reported in 1894 by
Zhigmondy. He called
these lesions
“keilformigen defekte”
(keel-shaped defects)
Historical Perspective
Non-Carious Cervical
Lesions are Not a
Modern Day
Phenomenon
11/29/2010
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Anthropological Research
by
Dr. Susan McEvoy
“Wedge-shaped cervical dental lesions in
two prehistoric Native American
populations”
- 1,100 specimens
- 5,000 years old
American J Physical Anthropology. 1996; Supp 22:162. Abstr # 22.
Archaeological Specimens
Courtesy Dr. Gene McCoy
Research Findings
The McEvoy study revealed that the same
types of non-carious cervical lesions that
are seen in modern-day man also were
present in pre-historic specimens, well
before the advent of the toothbrush!
Anthropological Research
by
Dr. Susan McEvoy
Epidemiological Study
Faye, B. et al. Noncarious cervical lesions among a non-toothbrushing population
with Hansen’s disease (leprosy): Initial findings. Quint Inter 2006; 37(8): 613-619.
Conclusions: “…toothbrush/dentifrice abrasion was not a factor in
the etiology of NCCL’s in the population studied.”
Co-variables noted:
- Acidic corrodents in diet (stress corrosion?)
- Parafunction documented in subjects
Non-carious Cervical
Lesions:
Does the Type of
Occlusion Matter?
YES!
Results of UNC study by Dr. Louis
Marion revealed that the risk for
cervical lesions was 6 times greater
for teeth in patients with group
function lateral guidance!
Occlusion Factors
-Marion LR, Bayne SC, Shugars DA, et al. Effects of occlusion type and wear on cervical lesion frequency. J Dent Res. 1997; 76:309; Abst # 2364.
-Hanoka K. et al. Occlusion and the non-carious cervical lesion.BulKanagawa Dent Coll. 2001; 29(2): 121-129.
Feline Dental Research
Okuda A, Harvey CE. Etiopathogenesis of feline dental resorptive lesions.
Veter Clinics North Amer: Small Animal Prac 1992; 22(6):1385-1404.
Conclusions: “…local mechanical trauma may be
an important factor in initiating the resorptivelesion.”
And “The etiopathology of feline resorptive
lesions may be considered as mechanical stress
including occlusal mechanism (sic)…”
Toothbrush Abrasion?
(Initial Lesion)
Feline Dental Research
(Advanced Lesions
Restored with GIC)
Feline Abfraction
Courtesy Dr. John Grippo
Before
Restored
Restored
11/29/2010
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Is this phenomenon due
solely to toothbrush and
dentifrice abrasion?
Absolutely Not!
In Addition to
Research Evidence, Common Sense Should Prevail!
Clinical Observations“Selective” Toothbrush
Abrasion?
Is This From
Toothbrush
Abrasion?
Is This From
Toothbrush
Abrasion?
“Selective” Toothbrush
Abrasion?
Courtesy Dr.
Randy Huffines
If so, why no lesion
on the most
prominent tooth?
Is This From
Toothbrush
Abrasion?
“Selective” Toothbrush
Abrasion?
Is This From
Toothbrush
Abrasion?
Sub-Gingival Lesion
Courtesy Dr. Richard Leaderman
Is This From
Toothbrush
Abrasion?
Sub-Gingival Lesion
11/29/2010
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Is This From
Toothbrush
Abrasion?
Sub-Gingival Lesion
Courtesy Matthew Korn
"Research and clinical observations support a
complex etiology which is most often multifactorial
in nature"
The “Bottom Line”
Revisited!
Toothbrush/dentifrice abrasion
is NOT the sole determinant or
cause of NCCLs.
Tooth flexure and its role in
weakening cervical tooth
structure clearly contributes to
the etiology of NCCLs.
Why are abfractions seen more frequently on
the facial rather than the lingual?
Several Theories Exist:
Functional movements are in an arcuate motion to
the facial.
Facial range function is more intense than lingual
range function or balancing, non-functional contacts.
Lingual cusps generally are volumetrically larger and
more resistant to tooth flexure.
If heavy parafunction is present,
abfractions can be seen on both
facial and lingual cervical areas.
Abfractions
Facial Lingual
Abfractions
How do you best treat abfractions?
• Limited occlusal adjustment?
• Occlusal nightguard or orthotic?
• Coverage with soft tissue graft?
• Desensitizer?
• Restoration?
Tooth Flexural
Effects on Restorations
11/29/2010
7
Heavy Centric Forces Heavy Eccentric Forces
What are the
effects on
cervical
restorations?
Tooth Flexure Effects
on Cervical
Restorations
Heymann HO, et al.
J Am Dent Assoc 1991; 122:41-47
Clinical Studies
Study Findings
Correlation between
stressful occlusion
and retention failures
Microfills retained better
than hybrids
Other Research
Materials that flex are best
suited for restoration of Class V
lesions.
Ichim IP et al. Restoration of non-carious cervical lesions Part II. Restorative material selection to minimize fracture. Dent Mater 2007; 23:1562-1569.
Microfilled Resins
Examples:
• Durafil VS (Heraeus Kulzer)
• Renamel Microfill (Cosmedent)
• Micronew (BISCO)
So what materials are best to accommodate
tooth biodynamics when restoring Class V’s?
Examples:
• Aeliteflo (BISCO)
• Tetric-Flow (Vivadent)
• Filtek Flow (3M ESPE)
• Star Flow (Danville)
Other Restorative
Systems
Flexible Posts
11/29/2010
8
• The etiology of non-carious cervical lesions is
multi-factorial
• Tooth brush/dentifrice abrasion is not the sole
determinant in the etiology of NCCLs
• Tooth flexure as a result of parafunction plays a
significant role in the pathogenesis of cervical
lesions (stress corrosion)
• Weakened cervical tooth structure from occlusal
stress likely is more susceptible to
dentifrice/toothbrush abrasion or erosion
Conclusions• Patient occlusion and the possibility
of parafunction should be assessed
when cervical lesions of unknown
etiology are found, particularly in
patients with group function
• Tooth dynamics must be considered
when selecting a restorative system
(lower elastic modulus)