Effects of different ceramic and dentin thicknesses on the temperature rise during photocuring

Background/purpose: The aims of this investigation were to describe the effect of different ceramic and remaining dentin thicknesses on substrate temperature during photocuring, and investigate whether the temperature increased by >5.5°C for different dentin/ceramic combinations. Materials and methods: Three groups of dentin thicknesses of 1.0 (D1.0), 1.5 (D1.5), and 2.0 mm (D2.0), and three groups of ceramic thicknesses of 1.5 (C1.5), 2.5 (C2.5), and 3.5 mm (C3.5) were examined. Temperature changes and the maximum temperature were observed under a high-intensity halogen light (QTH-Atralis 10 ECS program at 1200 mW/cm² for 30 seconds, Ivoclar Vivadent AG, Schaan, Liechtenstein). Four groups, D1.0-C1.5 (+11°C), D1.5-C1.5 (+7.2°C), D1.0-C2.5 (+6.7°C), and D2-0C1.5 (+5.8°C), demonstrated temperature changes of >5.5°C. Results and Conclusions: A statistical analysis showed that separate individual thicknesses and combinations of dentin and ceramic had significant effects on temperature changes (P < 0.01). It was observed that the ceramic exhibited a smaller temperature shielding effect than dentin. Clinically, it would be optimal to preserve the dentin to avoid damaging pulp tissues. Where there is insufficient overall thickness (≤3.5 mm), continuous high-energy output photocuring should be avoided to protect pulp tissues from thermal injury.