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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).

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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

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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

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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

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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

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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

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• 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)