Statement of problem: The increase in wall thickness of weakened roots using composite resins may increase the root resistance to fracture. However, little is known about the recently developed methods for intraradicular reinforcement of weakened roots.
Purpose: The purpose of this study was to determine the fracture resistance of experimentally weakened roots reinforced with composite resins, compared with conventional systems that use cast and prefabricated posts.
Material and methods: Forty-eight maxillary incisors were divided into 6 groups (n = 8). The control group (C) used a conventionally prepared root canal filled with cast CuAl posts. Experimental groups had the root canals overprepared to weaken them and were restored as follows: CP, cast CuAl posts; LT, light-transmitting polymerization post (Luminex) + Tetric Ceram resin + prefabricated titanium post (PTP); LF, Luminex posts + Filtek Supreme resin + PTP; LZ, Luminex posts + Z100 resin + PTP; and LR, Luminex posts + Renew resin + PTP. All posts were cemented with a resin luting agent (C & B Cement). Specimens were subjected to compressive load (N) until fracture. Data were submitted to 1-way analysis of variance and the Dunnett test (alpha = .05).
Results: There was significant difference (P < .01) between the conventionally prepared specimens and those filled with a cast post (C, 447.8 +/- 167.9) and the overprepared specimens and those filled with a cast post (CP, 212.8 +/- 62.4). No significant differences were found among the control specimens (447.8 +/- 167.9) and the weakened-roots filled with Luminex and composite resins LT (520.9 +/- 173.1), LF (479.9 +/- 214.9), LZ (391.6 +/- 173.6), and LR (333.0 +/- 112.2).
Conclusion: The use of composite resins in root canals reinforced the weakened roots during fracture resistance testing.