Evaluation of the Load-bearing Capacity of Fractured Incisal Edge of Maxillary Permanent Central Incisors restored with a Glass Fiber-reinforced Nanocomposite: An in vitro Study

Objectives: The aim of this study was to evaluate and comparethe load-bearing capacity of fractured incisal edge of maxillarypermanent central incisors restored with a nanocomposite anda glass fiber-reinforced nanocomposite.Materials and methods: Thirty-six extracted sound maxillarycentral incisors randomly divided in three groups were usedfor the present study. Group I (control) contained untreatedteeth. Samples in experimental groups II and III were preparedby cutting the incisal (one-third) part of the crown horizontallyand subjected to enamel preparations and restored with ananocomposite and a glass fiber-reinforced nanocompositerespectively. All restored teeth were stored in distilled waterat room temperature for 24 hours. Fracture resistance wasevaluated as peak load at failure (Newton) for samples testedin a cantilever-bending test using Hounsfield universal testingmachine. Failure modes were microscopically examined.Results: Highest mean peak failure load (Newton) amongexperimental groups was observed in glass fiber-reinforcednanocomposite group (863.50 � 76.12 N ) f ollowed bynanocomposite group (633.67 � 40.14 N). One-way analysisof variance (ANOVA) revealed that the restoration techniquesignificantly affected the load-bearing capacity (p < 0.001).Scheffe’s post-hoc comparison test (subset for a = 0 .05)revealed that there was significant difference in the mean peakfailure load values of nanocomposite and glass fiber-reinforcednanocomposite groups when considered together (p < 0.001).Experimental groups showed similar types of failure modeswith majority occurring as cohesive and mixed type. Fifty-eightpercent of the teeth in glass fiber-reinforced nanocompositegroup fractured below the cementoenamel junction. Conclusion: By using fiber-reinforced composite substructureunder conventional composites in the repair of fracturedincisors, the load-bearing capacity of the restored incisal edgecould be substantially increased.