STRENGTHENING IMMATURE TEETH DURING AND AFTER APEXIFICATION

The purpose of this study was to evaluate the strengthening effect of an internal resin bonding technique. One hundred central incisors were endodontically treated and divided equally into five groups. Group 1, without any cervical preparation and with access repaired with bonded resin, served as the positive control. Teeth in groups 2 to 5 were ce rvically prepared to simulate the thin dentinal wall of immature teeth , and obturation material was removed to 3 mm below the cementoenamel junction (CEJ). In group 2, the negative control, the access was resto red with bonded composite to the level of the CEJ. In group 3, access was restored with composite resin 3 mm apical to the CEJ using a clear post system. Group 4 was treated similarly to group 3, but an opaque post replaced the clear post. Group 5 was treated like group 3, after which a metal post was cemented into the channel left after removal of the clear post. All teeth were subjected to compression testing and t he force required to fracture the teeth cervically was recorded for ea ch group and the Kruskal-Wallis analysis performed to detect intergrou p differences. All of the bonded resin techniques significantly streng thened the teeth against fracture, compared with the negative control group (p < 0.05). None of the experimental groups (3-5) were significa ntly different from the positive control group.