ABSTRACT
Reconstruction of hard dental tissue after endodontic treatment is a difficult and important duty of the dentist. According to the general opinion, endodontically treated teeth are inferior in quality, more brittle, predisposed to fractures and crackings. The aim of the present study was to compare the fracture resistance of endodontically treated maxillary premolars including MOD cavities with different restoration methods. Ninety intact extracted human maxillary premolars were assigned to six different restoration methods. After endodontic treatment, MOD cavities with 2/3 inter cuspal distance was prepared and restoration was carried out by one of the following methods: Group I: Buccal and palatal cusps were reduced 2mm and were restored with indirect composite onlay. Group II: The cavity preparation was same as group I, and then were restored with porcelain onlay. Group III: Reduction of palatal cusp was done as much as 2mm. One semihorizontal threaded pin was placed in buccal cusp and then was restored with amalgam. Group IV: The cavities were prepared same as group III and were restored with posterior resin composite. Group V: The MOD cavities were restored with amalgam. Group VI: The cavities were restored with posterior composite. The teeth in all groups were subjected to thermocycling and mechanical loading. Then all specimens were loaded to failure with static force in a universal testing machine at 0.5 mm/min. The mode of fracture was determined using a stereomicroscope and classified according to 3 categories, cohesive failure of tooth, and cohesive failure of restoration and mixed. Data were analyzed with ANOVA and Tukey test [alpha=0.05]. ANOVA showed significant differences among groups [P<0.001] Tukey test found that the highest fracture resistance were in groups I, II, IV. The most unfavorable fracture site was occurred in group 1. Endodontically treated maxillary premolars with wide MOD cavities could be successfully restored by indirect composite and porcelain onlay and semihorizontal threaded pin plus composite
ABSTRACT
Background and Objective: Theoretical and clinical teachings in dentistry are not always according to the dentistry curriculum requirements, but they serve as the basis upon which Dentistry graduates start their own practice. The aim of this study was to find the resemblance between dentistry curriculum requirements with clinical experiences in restorative clinics of Mashhad Dental School in the two academic years of 2007 and 2008
Methods: Recorded data related to the teachings devoted to posterior Amalgam and Composite restorations were gathered from the archive of Restorative Department of Mashhad Dental School. Teaching volume was determined by considering the number of lecturers and sessions of preclinical exercises in the operative simulation laboratory during the General Dentistry program. Data available for direct posterior restorations placed by fourth, fifth and sixth year students were gathered from the students' report papers. The collected data were coded and categorized according to the surface number of posterior amalgam fillings [AFS1, AFS2, AFS3] and posterior composite fillings [CFS1, CFS2, CFS3]. These finding were placed on spreadsheets of Excel program and the related bar graphs were constructed for comparison of the devoted teaching volume and practice with the Dentistry curriculum requirements and the number of posterior amalgam and composite restorations
Results: Theoretical and practical teachings of amalgam and composite restorations have been in favor of amalgam with the ratio of 2 to 1. Clinically, practiced posterior composite restorations were 3 times more than the curriculum requirement. For the placement of three surface posterior restorations, amalgam favored over composite
Conclusion: Shift to the placement of posterior composite restorations needs to be addressed within dentistry curriculum, so the newly graduated dentists are prepared to place composite restorations properly