Tooth fragment reattachment through the use of a nanofilled composite resin

The purpose of this study is to evaluate resistance to fracture with static tests of dental fragments reattached through the use of different light-curing composite resins. For this purpose 40 bovine inferior incisors were utilised, which were randomised into 4 groups; one control group and 3 experimental groups.

All teeth of the 3 experimental groups were sawed at 3 mm from the incisal margin, and the respective fragments were then reattached utilizing different composite resins: in group 2_EI the hybrid composite Tetric EvoCeram (Ivoclar Vivadent AG) was used, in group 3_ZI the hybrid composite FiltekTM Z250 (3M ESPE) was used, and in group 4_SN the nanofilled composite FiltekTM Supreme (3M ESPE) was used. After reattachment, on each tooth were performed a chamfer on the buccal surface and an overcontour on the lingual surface along the fracture line, which were then filled with the composite resin corresponding to the respective group. Finally, all teeth were embedded in plaster blocks, and a force was applied on the buccal surface.

All teeth in groups 2, 3, and 4 showed a significant loss of resistance to fracture compared to the teeth of the control group (P<0.0001). Resistance to fracture of the teeth belonging to groups 2_EI and 3_ZI was 37.35% and 47.35% of that of intact teeth respectively; in group 4_SN resistance to fracture reached 60.05%. Teeth of group 2 exhibited values of resistance to fracture statistically significant from those of group 4 (P=0.024), but no difference was found between group 2 and group 3 (P=0.298). The difference in resistance between group 3 and group 4 was not statistically significant (P=0.199).

Static test showed that reattachment of coronal fragments do not restore resistance to fracture to the value of intact teeth. Resistance to fracture in in vitro studies is influenced by the type of composite resin utilised.