POSSIBLE IMPROVEMENTS OF CLINICAL PROPERTIES OF DENTAL COMPOSITE-MATERIALS WITH PULSED BLUE LASER CURING

Despite considerable improvements of dental composite materials, the p resent-day composite resins still suffer from two major shortcomings t hat limit their use: inadequate degree of conversion and polymerizatio n shrinkage. The objective of this study was to evaluate the degree of conversion and polymerization shrinkage of two hybrid and two microfi lled composite materials cured by pulsed blue dye laser pumped XeCl ex cimer laser at 308 nm and the standard curing unit. The degree of conv ersion was measured by a Perkin Elmer FTIR spectrometer at the surface of the material and at a 3.0 mm depth. Statistical analysis (ANOVA p < 0.05) showed a significantly higher degree of conversion values in t he case of pulsed laser. Polymerization shrinkage measured by a pycnom eter showed significantly lower values in the case of pulsed laser cur ing for six out of eight materials observed. The saturation effect in the material illuminated by monochromatic blue pulsed laser light (468 nm) may be responsible for the higher degree of conversion, while the relaxation of the molecules between nanopulses may lead to a reduced polymerization shrinkage.