مقايسه تاثير نوار ماتريكس شفاف و فلزي در ميزان پليمريزاسيون ترميم هاي كامپوزيت

Effect of Metal and Transparent Matrices on Micro Hardness of Posterior Composite Resin Restorations

Purpose: This study compared the degree of polymerization measured by micro hardness at gingival margin of a hybrid posterior composite restoration placed by different matrices. Method and Material: A human molar tooth extracted recently was selected in this study. After preparation a (3 m.m.wide, 2.5 m.m. deep, 4 m.m. tall) box in distal aspect of the tooth, it was mounted between two artificial teeth in a acrylic maxillary arch to simulate the geometric configuration of intraoral condition. This box preparation was used as a mold for preparing samples, so the walls were covered by one coat of biofilm as separator. Then samples were prepared by placing two horizontal increment of composite (tetric ceram). Four types of matrices and techniques were used to prepare samples: Group I -Metal matrix band and wooden wedge Each increment was light cured for 40 seconds, from the occlusal. Group 2 -Clear matrix band and reflective wedge Each increment was light cured for 40 seconds, from the occlusal. Group 3 - Metallic matrix band and wooden wedge Each increment was light cured for 40 seconds from occlusal and then after removing matrix band, light cured for 40 seconds at the buccal and 40 seconds at the lingual. Group 4 - Clear matrix band and reflective wedge Each increment was light cured for 40 seconds from occlusal and 20 seconds at the buccal and 20 seconds at the 1lingual. All resin composite specimens were mounted in acrylic molds and the hardness of the gingival surface was determined through Vickers hardness test. Data were analyzed by one - way analysis of variance (P < 0105). Result: Statistical analysis revealed there was no statistically significant difference between the groups. Conclusion: Based on these finding, the polymerization of the gingival surface doesnʹt differ through the usage of clear and metal matrices.