Temperature rise during photo-polymerization under ceramic restorations.

AIM The aim of this study was to measure the temperature increase induced by various light-curing units during photo-polymerization beneath ceramic restorations. METHODS Three light-curing units were used; a high intensity QTH unit Elipar 2500 and two LED units: Translux Power Blue and Excelled 1400. The 15 ceramic specimens (CEREC Blocks) used in this study were of 2.5 mm thickness, 5 mm wide and 6 mm long and made using a slow speed saw. Using the same slow speed saw the occlusal enamel portion of 15 mandibular third molars was removed and 15 dentin discs of 1 mm height were prepared. The thickness of the luting cement was delimited to 0.5 mm, using a Teflon mold and then brought into contact with the dentin disc. Light-curing time for all the groups was 20 sec. The temperature rise was measured placing underneath the dentin disc a K-type thermocouple wire connected to a data logger. Five measurements were carried out for each group. Statistical analysis was performed using ANOVA (a=0.05). RESULTS The results indicated that there was a lower temperature rise induced from Translux Power Blue than from the other two light-curing units, which did not present statistically significant difference (p<0.05). However, temperature rise from the light-curing units used in this study is lower than 5.5°C, which is the limit of pulpal damage. CONCLUSIONS Within the limitations of this study, although the type and characteristics of light-curing units may affect temperature rise under ceramic restorations, this influence is possibly not of clinical significance.