ABSTRACT

Microleakage resulting from polymerization shrinkage on composite resins is a major cause of clinical failures in modern dentistry. This slow process produces a progressive unsuccessful restoration. In this in vitro study, class V cavities (2x3 mm in width and 1.5 mm in depth) were prepared on the buccal surfaces of 60 deciduous teeth. The apical foramina of teeth were sealed with a layer of varnish and composite restorations. Samples were divided randomly into three groups containing 20 teeth each and restored with Compoglass® F per manufacturer's instructions. Photo-activation was performed by 1) continuous light (500 μW/cm2) for 40 seconds, 2) stepped light with low intensty (150 μW/cm2) for 10 seconds and high intensity (500 μW/cm2) for 30 seconds, and 3) intermittent light (450 μW/cm2) for 60 seconds. All specimens were thermocycled between 5 to 55oC for 1000 cycles with a 30-second dwell time, followed by immersion in %0.2 basic fuccine for 24 hours. The crowns of the teeth were separated in bucco-lingual direction and examined by stereomicroscope to determine microleakage levels. Degree of leakage was classified on rates from zero to three (0=no leakage, 1=dye penetration up to one-half of the preparation depth, 2=dye penetration more than one-half preparation depth but less than the axial wall, 3=dye penetration along the axial wall). In conclusion, microleakage levels in Group 1 were higher than those in the other groups, and there was no significant difference between the Groups 2 and 3. When all the groups were compared, Groups 2 and 3 had low microleakage levels on occlusal and cervical walls of the cavities. Inter-group comparisons showed that microleakage levels on cervical walls were significantly higher than those on the occlusal walls.