Evaluation of fracture resistance and sites of failure of different dowel core restorations: An in-vitro study

Background: Dowel Cores are often required in endodontically treated tooth to aid retention and resistance for a final prosthetic crown. Studies concerning the role of post-core systems on the fracture resistance with different dowel material remain controversial. Aim: This experimental study aimed to investigate the fracture resistance strength and failure mode of 3 dowel systems (glass fiber, indirect resin, and prefabricated metal with resin core). Methods: Twenty-one extracted human maxillary central incisors were first endodontically treated and then separated into 3 equal groups randomly;1^st group consisted of glass fiber dowel, 2^nd group consisted of indirect resin dowel, and 3^rd group consisted of the prefabricated metal dowel. All specimens were restored with resin core and indirect resin crown. A testing force was applied with a universal testing machine (at 135^o angle) at 3 mm from the incisal edge of crown and forces were measured. Statistical tests were done using One-way ANOVA and Chi-square Test. Results: There was no significant difference (P-value >0.05) of the fracture resistance among glass fiber dowel, indirect resin dowel and pre-fabricated dowel with indirect resin crown. The prefabricated metal dowel had maximum fracture resistance (566 ±157.771 N) followed by Glass fiber dowel (541.047 ±199.571 N) and indirect resin dowel and post (444.550 ±139.788 N). Conclusion: Glass fiber dowel, indirect resin dowel and prefabricated metal dowel with resin core and indirect resin crown systems showed statistically insignificant fracture strength values and mode of failure.