Comparative evaluation of the fracture resistance and fracture patterns of endodontically treated anterior teeth restored with two different esthetic posts: An In Vitro study

The present in vitro study was conducted to comparatively evaluate the fracture resistance and fracture patterns of endodontically treated anterior teeth restored with two different esthetic posts, namely glass fibre posts and zirconia posts. A total of twenty freshly extracted, maxillary central incisors were used in this study. They were randomly divided into two test Groups A and B of ten samples each. All the samples were endodontically treated. Tooth preparation was done to obtain a 2mm ferrule for the crown and post space preparation was done uniformly for all the samples and the teeth. Group A test samples were restored with glass fibre posts and Group B with zirconia posts. All the samples were then subjected to core build up with light cure composite material. Nickel chromium cast copings were fabricated and cemented to the prepared teeth with post-core. All the samples were embedded in acrylic resin block with the periodontal ligament simulation and subjected to static loading in universal testing machine. The maximum load at which fractures occurred for all the test samples were recorded and tabulated. Statistical analysis was made with independent student’s T test and P value less than 0.05 was considered significant. Samples with zirconia posts exhibited greater fracture resistance than those with glass fibre posts. However, the differences in the mean values between the two Groups were not statistically significant. This study indicates that both the esthetic posts, namely glass fibre and zirconia posts exhibited similar fracture resistance statistically. The fracture patterns with respect to locations of fractures were also tabulated for Group A and Group B samples. Visual inspection of the fracture patterns of the endodontically treated anterior teeth restored with glass fibre and zirconia posts have revealed that use of zirconia posts exhibited 60% of the root fracture while glass fibre posts exhibited 60% of crown fractures. The choice of an appropriate restoration of endodontically treated teeth is guided by strength and esthetics. Cast metal post and core foundation have a long history of successful use due to the superior physical properties. However, esthetics properties of these materials are limited when used to support the all-ceramic restorations, in the prosthetic rehabilitation of maxillary anterior region. The Prefabricated posts made of tooth coloured material such as glass fibre or zirconia have become popular because they increase the transmission of light within the roots and overlying tissues. In this in vitro study, the post and core foundations with glass fibre and zirconia posts exhibited higher values of fracture resistance (798.20 N, 840.60 N) than the maximum physiological forces of 200N acting on the teeth in the oral cavity.40 Therefore, it may be suggested that endodontically treated anterior teeth restored with these posts would resist normal occlusal forces. Hence, these posts can be used as an alternative to cast post core or prefabricated metallic posts in the maxillary anterior region. Further studies to examine fracture mechanics, as well as long-term clinical investigations are needed to evaluate the performance of glass fibre and zirconia posts