The Effect of Variable Environmental Pressure on Microleakage of Direct and Indirect cIV Composite Restorations

an air void between the restoration and tooth because of Variable Environmental Pressure can lead to pulpal pain or fracture of the tooth or restoration.

60 molar teeth  divided to 2 groups. Preparation in Group A was a Cl V cavity in wich the Gingival margin was 1mm under CEJ while the occlusal margin was in  enamel. For Group B, we followed the same procedure plus a 0.5mm bevel with 45 degree angle in the enamel margin. Group A was filled with composite inlays of Filtek Z250 (3M ESPE, St. Paul, MN, USA). Group B was restored directly by the same composite.Each group were divided into control and case groups. The case specimens were put into 96 cycle pressure for 0 to 5 atm. Then the specimens were put in distilled water and were kept in silver nitrate solution. After washing them with water, they put in radiographic developer solution under fluorescent light. Finally, they were cut by a  diamond disc and the microleakage were studied under a stereomicroscope with 20X magnification. Data was evaluated using two-way nonparametric model

There was no significant difference between direct and indirect restorations, both in fixed and variable pressures in the occlusal walls. P=0.1 Besides, in both direct and indirect groups there was a significant difference in gingival wall between fixed and variable pressure, in a way that in fixed pressure, there was less microleakage. (P=0.000)

Changing in environmental pressure increase the microleakage in direct and indirect restorations.