EFFECT OF RESTORED AND UNRESTORED NONCARIOUS CERVICAL LESIONS ON THE FRACTURE-RESISTANCE OF PREVIOUSLY RESTORED MAXILLARY PREMOLAR TEETH

Objectives: 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 grou p of extracted maxillary premolar teeth with mesio-occlusal-distal (MO D) restorations of amalgam, and restored or unrestored simulated NCCL. Method: Forty sound maxillary premolar teeth were divided at random i nto four groups, each of 10 teeth, which were fixed crown uppermost an d long axis vertical in stainless steel moulds. Groups 1, 2, 3 and 4 w ere prepared with standardized parallel-sided MOD cavities, then resto red with amalgam. Groups 1, 2 and 3 were further prepared with standar dized NCCL. The NCCL in Group 1 were restored using a resin-modified p olyalkenoate (glass-ionomer) cement, and the NC:CL in Group 2 were res tored with an adhesive composite resin system. The NCCL in Group 3 wer e 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 Grou ps 1, 2, 3 and 4. Two-way ANOVA and Scheffe's Multiple Range Test show ed no statistically significant difference between the groups. Conclus ions: It is concluded that the presence of a standardized NCCL in an e xtracted maxillary premolar tooth does not reduce the fracture resista nce of the tooth when loaded compressively at 1 mm min(-1). The restor ation 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). (C) 1998 Elsevier Science L td. All rights reserved.