Fracture resistance of maxillary lateral incisors restored with different post systems

Fracture resistance of endodontically treated teeth is low and they are more prone to biomechanical failure. Endodontically treated maxillary central incisors when restored with post show increase fracture resistance. The remaining thickness of dentine at Cemento-Enamel Junction (CEJ) in maxillary incisors is minimal due to access cavity and crown preparation. The aim of this study was to assess fracture resistance of maxillary lateral incisors with and without post. Forty human maxillary lateral incisors free from caries, restoration and previous endodontic treatment with similar shape and root length were collected. Teeth were divided randomly into 4 groups (n = 10 each). Group 1 was restored with glass fiber post, group II with zirconia post, group III with cast post and core and group IV represented a control group without post and core. All teeth were restored with all-ceramic crowns. The specimens were exposed to increasing compressive load in universal testing machine at a crosshead speed of 0.01 cm/min until fracture. The pattern of fracture was classified into restorable (above CEJ) and non-restorable (below CEJ). Maximum load to failure was compared between four experimental groups by ANOVA and p value <0.05 was considered as statistically significant. The lowest mean load to failure was shown in specimens of group-IV (175.3±33.40) and highest was noted in group-II (311.21±51.77). The mean loads to failure ingroup III (248.58±38.40) and group I (231.26±43.67) were comparable. In groups IV and I, 100% and 80% of failures were above CEJ respectively. In groups II and III, 50% and 40% of failures was above and below CEJ respectively. The loads required to fracture lateral incisors restored with zirconia post were higher compared to those restored with glass fiber and cast post and core. Therefore, zirconia posts are recommended for clinical applications for longer survival and better prognosis of restored endodontically treated teeth.