Fracture resistance of incisal tooth fragment reattached with different adhesive materials and retentive techniques

OBJECTIVE: This study evaluated in vitro the shear bond strength of experimentally fractured human tooth fragments reattached with different adhesive materials and retentive techniques.METHODS: Forty-eight sound mandibular incisors were randomly divided into 6 groups (n=8). Their incisal edges were cut off in 5 groups, representing an enamel-dentin fracture. Intact teeth were used as control (Group 1). The fragment edges were reattached with adhesive system (Scotch Bond Multipurpose – 3M ESPE) (Group 2), adhesive system and composite resin (ICE – SDI) (Group 3), adhesive system and composite resin with circumferential bevel (Group 4), adhesive system and composite resin with internal dentin groove (Group 5), and adhesive system and composite resin with the circumferential bevel and internal dentin groove (Group 6). Shear bond strength was determined in a universal testing machine. Fracture modes were identified by light microscope. Kruskal-Wallis was used to analysis resistance to fracture and fracture patterns.RESULTS: The results showed statistically significant differences (p<0.05) among groups. The intact teeth (Group 1) showed higher fracture resistance than the other groups. Groups 2 and 6 did not differ and were statistically superior to other techniques. Group 4 presented statistically higher than in Group 5, which in turn was more resistant than Group 3.CONCLUSIONS: None of the fragment reattachment techniques was able to achieve the strength of sound teeth. Fragments reattached only with adhesive system or with adhesive system and composite resin with the circumferential bevel and internal dentin groove showed the best performance for resistance to fracture.