Reattachment of rehydrated dental fragment using two techniques

The reattachment of dental fragments is a conservative treatment and should be considered in the restoration of anterior tooth fractures. This study compared the fracture strength of dehydrated and rehydrated tooth fragments submitted to two different bonding techniques. Materials and Methods: Sixty human central and lateral mandibular incisors were divided into six groups and sectioned 3 mm from the incisal edge, using a diamond disk. Two reattachment techniques were applied: (a) bonding, using the Single Bond adhesive system and FiltekZ250 composite resin, followed by placement of a chamfer on the fracture line that was filled with composite resin (Groups 1, 3 and 5); and (b) use of the same bonding technique after dentin removal from the tooth fragment (Groups 2, 4 and 6). The following hydration treatments were applied to the fragments before bonding: (a) 48-h hydration (Groups 1 and 2); (b) 48-h dehydration (Groups 3 and 4); (c) 48-h dehydration followed by rehydration 30 min before bonding (Groups 5 and 6). The reattached teeth were mounted in acrylic resin cylinders and stored in distilled water for 24 h. The specimens were fractured at a speed of 1 mm min^-1 in a universal testing machine. Results: The following mean fracture strengths (kgf) were recorded: (G1) 12.9 ± 0.6; (G2) 18.8 ± 4.8; (G3) 7.3 ± 1.5; (G4) 15.2 ± 2.4; (G5) 13.4 ± 2.2; and (G6) 17.1 ± 3.2. Analyses using two-way anova and the Tukey test (P < 0.01) revealed significant differences between the restorative techniques and the hydration treatments. Conclusions: The bonding technique that incorporated dentin removal from the fragment before bonding showed greater fracture strength across all groups. Fragment dehydration for 48 h caused a reduction in fracture strength, which was recovered by a 30-min rehydration.