Effect of restored and unrestored non-carious cervical lesions on the fracture resistance of previously restored maxillary premolar teeth.
OBJECTIVE
The effect of non-carious cervical lesions (NCCL) on tooth fracture resistance has not previously been investigated. The aims of this in vitro study were to examine the fracture resistance of a group of extracted maxillary premolar teeth with mesio-occlusal-distal (MOD) restorations of amalgam, and restored or unrestored simulated NCCL.


METHODS
Forty sound maxillary, premolar teeth were divided at random into four groups, each of 10 teeth, which were fixed crown uppermost and long axis vertical in stainless steel moulds. Groups 1,2,3 and 4 were prepared with standardized parallel-sided MOD cavities, then restored with amalgam. Groups 1, 2 and 3 were further prepared with standardized NCCL. The NCCL in Group 1 were restored using a resin-modified polyalkenoate (glass-ionomer) cement, and the NCCL in Group 2 were restored with an adhesive composite resin system. The NCCL in Group 3 were left unrestored. The specimens were loaded compressively at 1 mm min-1 using a universal testing machine.


RESULTS
Mean fracture loads (KN) of 1.08, 1.03, 0.98 and 1.14, respectively, were recorded for Groups 1, 2, 3 and 4. Two-way ANOVA and Scheffe's Multiple Range Test showed no statistically significant difference between the groups.


CONCLUSIONS
It is concluded that the presence of a standardized NCCL in an extracted maxillary premolar tooth does not reduce the fracture resistance of the tooth when loaded compressively at 1 mm min-1. The restoration of NCCL with the materials tested did not result in an increase in the fracture resistance of the previously restored premolar teeth, when loaded compressively at 1 mm min-1.
University Dental Hospital of Manchester, UK.
K L
KL
Osborne-Smith
F J
FJ
Burke
T M
TM
Farlane
N H
NH
Wilson
D000704:Analysis of Variance; D001641:Bicuspid / Q000473:pathology* / Q000503:physiopathology; D003188:Composite Resins; D019245:Compressive Strength; D003723:Dental Amalgam; D003737:Dental Cavity Preparation / Q000145:classification; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000145:classification; D003799:Dental Stress Analysis; D004198:Disease Susceptibility; D005899:Glass Ionomer Cements; D006801:Humans; D008437:Maxilla; D014072:Tooth Abrasion / Q000503:physiopathology / Q000628:therapy*; D019237:Tooth Cervix / Q000473:pathology* / Q000503:physiopathology; D014077:Tooth Erosion / Q000503:physiopathology / Q000628:therapy*; D014082:Tooth Fractures / Q000145:classification / Q000503:physiopathology
D003188:Composite Resins; D005899:Glass Ionomer Cements; D003723:Dental Amalgam