EFFECT OF LIGHT CURING UNIT AND HEAT TREATMENT TEMPERATURE ON POLYMERIZATION DEGREE AND FLEXURAL STRENGTH OF DIRECT RESIN COMPOSITE FOR INDIRECT APPLICATION
MAYA HUDIYATI, Dr. drg. Widjijono, SU.
2011 | Tesis | S2 Kedokteran Gigi-
Resin composites are extensively tooth-colored materials used today to restore the patient’s dentition directly and indirectly. The indirect application have some advantages such as increased degree of polymerization and improved physical and mechanical properties, and this can be fabricated from commercial direct resin composites associated with heat treatment after photocuring in a digital oven with the various temperatures. The different types of light curing unit have an impact on the resulting light intensity, and may affect the degree of polymerization. Flexural strength is one important factor for indirect restorations and it can be affected by the polymerization degree. The aim of this study was to evaluate the effect of light curing units and various heat treatment temperatures on the polymerization degree and flexural strength of direct resin composite for indirect application. This research was an experimental study, using 60 specimens of a resin composite divided into 12 groups. They were quartz tungsten halogen (QTH) and light emitting diode (LED) groups heated respectively at temperatures of 280C (control group), 149, 159, 169, 179 and 1890C. Measurement of flexural strength used the universal testing machine, polymerization degree used the fourier transform infrared spectroscopy (FTIR). The results were analyzed by two way anova and least significant difference (LSD) tests. The results of this study showed that the mean of polymerization degree and flexural strength increased from the control group of QTH and LED to the groups heated above the room temperature. The lowest polymerization degree (54.72 ± 0.83) and flexural strength (13.20 ± 5.63) were in the control group of QTH. The highest polymerization degree (62.54 ± 0.74) was in the LED group heated at 1790C, while the highest flexural strength (72.30 ± 30.59) was in the QTH group heated at 1890C. The results of two way anova test showed that light curing unit (LCU) was different significantly for the polymerization degree (p < 0.05), but not for the flexural strength (p > 0.05); whereas temperature was different significantly for the polymerization degree and flexural strength (p < 0.05). The interaction between LCU and temperature was not significant (p > 0.05). There were weak relationships between temperature and polymerization degree, also flexural strength. It can be concluded that: LED induced the polymerization degree higher than QTH, while LED induced the flexural strength as well as QTH did; temperature rising at the heat treatment increased the polymerization degree and flexural strength; there was no interaction between LCU and temperature in affecting the polymerization degree and flexural strength of direct resin composite for indirect application.
Kata Kunci : direct resin composite, light curing unit, heat treatment temperature, polymerization degree, flexural strength
