Different Pile Of Nuclear Material And Hoop Structure With Premolar Resistance, Experimental Studies

objective To evaluate the fracture resistance of endodontically, this study was to evaluate the fracture resistance of endodontically treated mandibular premolars restored with glass fiber posts and casting post when different types of ferrule designs were incorporated.Methods eighty-eight mandibular premolars were divided into three groups:Group A is casting post,Group B is fiber post.Group C is not post. A, B group is divided into 5 groups, each with eight samples. Group 1:teeth with a 1mm circumferential ferrule; Group 2:teeth with a lmm ferrule only in the buccal region; Group 3:teeth with a 1mm ferrule only in the lingual region; Group 4:teeth with a 1mm ferrule in the buccal and lingual region; Group 5:teeth with no ferrule. A, B groups were used to casting post, fiber posts before restored with porcelain fused to metal crown. Group C(control):teeth with root canal treatments having a full crown prosthesis.All experimental teeth were subjected to an increasing compressive force with a crosshead speed of 1mm/min, until fracture occurred.Results (1)Group A:The loading force value in first group is 1383.3±187.6N, which is significantly higher than 1067.6±234.3N in the control group (p<0.01); The loading force value in first group is 1067.6±234.30N, which is significantly higher than 668.9±230.90N in the sixth group (p<0.05). The difference in remaining groups were not statistically significant.(2)Group B:The fifth group of the loading force value (668.9±230.90N) than the control group, there is significant difference (p<0.05). The difference in remaining groups were not statistically significant.(3) The comparison values of loading force between different post and core with the same ferrule structure shows that Al (1383.3±187.6N) and B1 (837.5±228.0N) there are differences (p=0.001), no difference between other groups.(4) The comparison of fracture mode between different post and core with the same ferrule structure shows that A2 and B2 (p=0.026), A3 and B3 (p=0.007), A5 and B5 (p=0.001) were significant differences. No difference between other groups.Conclusion It was concluded different ferrule designs did not have any influence on the fracture resistance of mandibular premolars with fiber posts. And when the remaining tooth structure is less, the fracture mode for the repair-type. Therefore, Fiber post and core can be used for a variety of mandibular premolars, with a wide range of prospects.