Fracture Resistance Of Endodontically Treated Teeth With Class II Or Class V

Method: Seventy mandibular premolars were randomly categorized into seven groups of ten each. Group 1 was sound premolars (control). Group 2 to 7 were received a root canal treatment and then restored with different methods, i.e., Group 2, 4 and 6 were Class I access, II and V preparation and then restored with resin composite, whereas Group 3, 5 and 7, were Class I access, II and V preparation and then restored with resin composite in conjunction with fiber posts. All samples were thermocycled at 5 and 55 °C for 10,000 cycles. The fracture resistance was performed by using the universal testing machine, with a stainless steel spherical ball (diameter 4 mm) and loading at 45°angle to horizontal plane with cross head speed 10 mm/min until fracture occurred. Data were analyzed with Two-way ANOVA and Bonfferoni test.

Result: The results showed that the fracture resistance of the endodontically treated mandibular premolars with different cavity designs was significantly different from each other with p-value<0.005, i.e., mean of fracture resistance of cavity Class II was significantly less than Class I access about 115.8 N (95%CI 31.8-199.9 N) with p-value = 0.004.  Whereas the effect of fiber post and interaction between type of cavity and fiber post on fracture resistance, were not significantly different (p-value = 0.890 and 0.082).

Conclusion: This study showed that cavity design affects the fracture resistance of endodontically treated mandibular premolars, whereas using of fiber posts did not enhance the fracture resistance of the endodontically treated mandibular premolars presented with different cavity designs.