EVALUATION OF THE EFFECTS OF DIFFERENT FERRULE DESIGNS ON THE MANDIBULAR PREMOLARS INCORPORATING FIBER POSTS,COMPOSITE CORES AND CROWN RESTORATIONS

Objective To evaluate the fracture resistance of endodontically treated mandibular premolars restored with quartz fiber posts,composite cores,and crowns when different types of ferrule designs were incorporated.Methods Forty-eight mandibular premolars were divided into six groups: Group 1: teeth with root canal treatments having a full crown prosthesis;Group 2: teeth with a 1mm circumferential ferrule;Group 3: teeth with a 1mm ferrule only in the buccal region;Group 4: teeth with a 1mm ferrule only in the lingual region;Group 5: teeth with a 1mm ferrule in the buccal and lingual region,;and Group 6: teeth with no ferrule.All the extracted teeth were restored with quartz fiber posts-composite cores and porcelain fused to metal crowns. All experimental teeth were subjected to an increasing compressive force with a crosshead speed of 1mm/min until thec fracture occurred.Results The loading force value(1067.6±234.30N)in the first group was hjigher than the sixth group(668.9±230.90N),and there was significant difference between them(P0.05).The remaining groups showed no statistical significance.Conclusion Fiber post and core can be used for a variety of mandibular premolars with a wide range of prospects.