Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin

Objective

The aim of this study was to evaluate the effect of multiple layers of aninfection control barrier on the micro-hardness of a composite resin.

Material and Methods

One, two, four, and eight layers of an infection control barrier were used tocover the light guides of a high-power light emitting diode (LED) light curingunit (LCU) and a low-power halogen LCU. The composite specimens werephotopolymerized with the LCUs and the barriers, and the micro-hardness of theupper and lower surfaces was measured (n=10). The hardness ratio was calculated bydividing the bottom surface hardness of the experimental groups by the irradiatedsurface hardness of the control groups. The data was analyzed by two-way ANOVA andTukey''s HSD test.

Results

The micro-hardness of the composite specimens photopolymerized with the LED LCUdecreased significantly in the four- and eight-layer groups of the upper surfaceand in the two-, four-, and eight-layer groups of the lower surface. The hardnessratio of the composite specimens was <80% in the eight-layer group. Themicro-hardness of the composite specimens photopolymerized with the halogen LCUdecreased significantly in the eight-layer group of the upper surface and in thetwo-, four-, and eight-layer groups of the lower surface. However, the hardnessratios of all the composite specimens photopolymerized with barriers were <80%.

Conclusions

The two-layer infection control barrier could be used on high-power LCUs withoutdecreasing the surface hardness of the composite resin. However, when using aninfection control barrier on the low-power LCUs, attention should be paid so asnot to sacrifice the polymerization efficiency.