Effect of eccentric load cycling on microleakage of class V flowable and packable composite resin restorations

Class V composite restorations are subject to the stresses that induce non- carious cervical lesions. This study evaluated the effect of eccentric obli que load on microleakage of restorations. Class V cavities were randomly pr epared on the buccal surfaces of 40 recently extracted premolars and restor ed with composite resin according to manufacturers' directions. Teeth were randomly assigned to one of four treatment groups with 10 teeth per group: (1) flowable resin (Revolution) without load cycling; (2) packable resin (P rodigy Condensable) without load cycling; (3) flowable resin with load cycl ing (200,000 cycles) and (4) packable resin with load cycling (200,000 cycl es). All teeth were then immersed in 2% methylene blue solution for 24 hour s after thermocycling (500 cycles). Dye penetration was measured (scores 0- 3). The results indicated that adding load cycling significantly increased microleakage (p <0.05). No significant differences in microleakage were obs erved for flowable resin vs packable resin. Gingival margins had significan tly more microleakage (p <0.05) than occlusal margins.