Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Operative Dentistry

This study was carried out to verify the effect laser pretreatment on sealing ability of resin composite restorations bonded with two different adhesive approaches. A total of one hundred and twenty freshly extracted caries-free human mandibular posterior teeth were selected for this study. The teeth were divided into two main groups according to laser pretreatment. Each group was divided into two subgroups according to the type of adhesive system(total etch system or self-etch adhesive system. Each subgroup was divided into two classes according to aging period (one day, one month and 3 months). Standardized class V were prepared with the following dimensions (3 mm occlusogingival, 2 mm bucco-lingual, 2 mm mesio-distal). All restorative materials were applied according to the manufacturer{u2019}s instructions. Each restoration was finished with fine grit finishing diamond stones and was polished with fine and superfine Al₂O₃ discs. All samples were stored in distilled water. For specimens aged for 1 and 3 months, distilled water was changed every twice weekly .For microleakage testing, the specimens were immersed in 2% aqueous solution of methylene blue for 24 hours. Teeth were longitudinally sectioned in a buccolingual direction

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