Incisal edge reattachment: The effect of preparation utilization and design

Objective: This study evaluated the effect of preparation utilization and d esign, and addition of resin composite to the bonding interface, on the fra cture resistance of reattached incisal fragments. Method and materials: Six ty bovine incisors were distributed among 1 control group and 5 experimenta l groups. Experimental specimens were sectioned 3.0 mm from the incisal edg e with a 0.15-mm wafering blade at a 25-degree inclination apically in a fa ciolingual direction. Two groups received no further preparation. Specimens in the other 3 groups received either external bevels, internal bevels, or combined external and internal bevels. One preparationless group was reatt ached with dentin bonding agent alone. All other fragments were reattached with a dentin bonding agent-resin composite interface. After thermocycling and 4 weeks of bond weathering, specimens were sheared to failure in a univ ersal testing machine. Results: No significant differences in fracture stre ngth were observed among any of the experimental groups, yet each displayed significantly less resistance to fracture than the control group. Reattach ment of fragments in all groups restored approximately one half or one thir d the fracture strength of the control teeth for crown or root fractures, r espectively. Conclusion: Compared to the simple, expedient regimen of using a dentin bonding agent alone, nonconservative tooth modification and the a ddition of resin composite to the bonding interface did not increase resist ance to fracture and thus provided no retentive advantage.