Microleakage of Class II box-type composite restorations

To investigate whether in small box-type Class II preparations the use of glass ionomer cement, a dentin primer or a different type of conditioner had an effect on the microleakage compared to a more simple total-etch system using a phosphonated bonding agent.

In extracted premolars, 84 box-type Class II composite resin restorations with margins in enamel were made following a standardized protocol. A transparent matrix system was used and the composite resin was applied in two layers. The teeth were restored using a phosphonated total-etch bonding system as a control (Photo Bond). In the experimental groups a glass ionomer lining-cement (Vitrebond), a total-etch adhesive including a primer (Scotchbond Multi-Purpose) and a total-etch adhesive using a self-etching primer (Liner Bond 2) were used. The teeth were thermocycled, immersed in a dye solution and sectioned. The cervical and occlusal dye penetration was assessed.

Preventing microleakage was not more effective in the experimental groups than in the control group (P < 0.05). Scotchbond MP groups using maleic acid showed statistically significant more microleakage than the control group (Photo Bond) at the cervical side. Liner Bond 2 and Scotchbond MP groups using maleic acid showed statistically significant more microleakage than the control group at the occlusal side. The use of a lining cement did not improve the quality of the restoration. From this study it was concluded that in this type of restoration, total-etch systems using a primer are not always an improvement.