Microleakage of posterior packable resin composites with and without flowable liners

The use of flowable composites as liners in Class II packable composites ha s been suggested by some manufacturers. However, the contributions of this technique are unproven. This study evaluated marginal microleakage in Class D packable composite restorations with and without the use of a flowable c omposite liner. A conventional microhybrid composite was used as a control. Microleakage at occlusal and gingival margins of Class II cavities was eva luated using Ca-43 and autoradiographs. Fifty non-carious, restoration-free human molar teeth were used. Separate m esio-occlusal and disto-occlusal Class II cavity preparations were made in each tooth. Gingival margins of all cavities were placed 1 mm apical to the cementoenamel junction (CEJ). Four Packable composites (Alert, Surefil, Py ramid and Solitaire) and one conventional microhybrid composite (Renew) wit h their respective manufacturer's bonding agents were used to restore the c avities. One side of each tooth was restored with composite alone, while th e other side was restored with the composite lined with that manufacturer's flowable liner. The restored teeth were thermally stressed and 45Ca was us ed to evaluate microleakage. Two independent evaluators scored leakage base d on the autoradiographs. The results showed flowable composites helped reduce microleakage at gingiv al margins of Class II restorations (p <0.05). Gingival margins had higher microleakage than occlusal margins (p<0.05). Without flowable liners, three packable composites (Alert, Pyramid and Surefil) showed higher leakage (p< less than>0.05) than the microhybrid control. Only Solitaire packable compo site without liner showed no significant difference in microleakage to the control (p >0.05). Although the flowable liners help reduce microleakage, A lert and Pyramid packable composites with liners still showed higher leakag e than the control (p<0.05). Surefil and Solitaire packable composites with flowable liners showed no significant difference in microleakage (p<greate r than>0.05) to the control.