الفهرس 
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Abstract
This study was performed to evaluate a one year clinical follow up of Bulk fill composite (Tetric N Ceram) in sandwich technique using two different lining materials either flowable composite (Tetric N Flow) or light curing glass ionomer cement (Ionoseal). Twenty patients participated in the study (4 males & 16 females aged 25- 45 years) where a total of 60 posterior teeth (9 molars & 41 premolars) were restored with either bulk fill composite only, bulk fill composite with flowable composite liner or bulk fill composite with glass ionomer liner representing three main groups (20 teeth each). Each patient received at least three types of restorations. The distribution of material, type and tooth location was randomized. Cavity designs were restricted to eliminate carious tissues from primary caries. No beveling was performed. Calcium hydroxide was placed in deep areas. All materials were used according to the respective manufactures’ directions. A thin layer of the lining material was applied then composite resin was inserted in bulk and light cured. Excess material was removed then restorations were finally finished and polished under water cooling. All restorations were subjected to a periodic clinical follow up schedule at base line, 6 months and 12 months during which two investigators rated the restorations according to the modified United States Public Health Service (USPHS) criteria regarding retention, color matching, marginal discoloration, marginal adaptation, secondary caries, surface texture, anatomic form, and postoperative sensitivity. The examiners were not involved in the placement of the restorations and were unaware of the materials used. In this double- blind study, when disagreement aroused during evaluation they reevaluated the restorations together and determined the score by consensus. For confirmation of the clinical findings, the marginal seal of some representative restorations were verified by examining the marginal integrity by scanning electron microscope using an epoxy resin replica. The data obtained from the clinical evaluation at different follow up periods were collected, tabulated and statistically analyzed to determine the difference in performance of the tested techniques using Chi square test. Results revealed no statistically significant difference between the three tested groups at different follow up periods (P > 0.05). Spearman’s test revealed a statistical positive correlation between marginal adaptation versus both marginal discoloration and anatomic form as well as marginal discoloration versus both surface texture and color match.