The effect of cusp capping with composite resin on fracture resistance of premolars with prepared endodontic access cavities: An in vitro study

Introduction: The purpose of this study was to evaluate the effect of remaining dentinal wall thickness and the effect of remaining cusp height of endodontically treated premolars when restored with composite resin. Materials and Methods: Ninety premolars were divided into 4 test groups (n = 20) and 2 control groups (n = 5). In all groups, except the negative control group (sound teeth), standardized endodontic access cavities were prepared, pulp extirpated, mesioocclusodistal (MOD) cavities prepared and access sealed with Light Cure Glass Ionomer Cement (LC GIC). Test groups were divided as:- Cusp reduction for Groups I and II- 2.5 mm and for Groups III and IV- 1.5 mm. Dentinal wall thickness for Groups I and III- 1-1.5 mm and Groups II and IV- 2-3 mm. The groups were further subdivided into Subgroup A, restored with P60 and Subgroup B, restored with Herculite Precis. Positive control- only access cavity with no cusp reduction and restoration. Fracture resistance was assessed using Universal Testing Machine (UTM). Results: Highest fracture resistance was demonstrated by Group VI and least by Group V. Groups VI, II and I, showed statistically insignificant difference for both the composites (P > 0.05). Groups III and IV showed statistically significant difference only for Subgroup B. Conclusion: When the cusp reduction was 2.5 mm, dentinal wall thickness had no effect on the fracture resistance, for both the composites. When the cusp reduction was 1.5 mm and the remaining dentinal thickness was 1-1.5 mm, Herculite Precis showed inferior results to P60.