Heat Induced Changes to Dental Resin Composites: A Reference in Forensic Investigations?

The objective was to investigate color change and surface damage in dental resin composites exposed to high temperatures over different time intervals for comparative purposes. Samples were prepared using two resins - Z100® (R1) and Charisma ® (R2), heated at the following temperatures: 200°C, 400°C, 600°C, 1000°C, for 15, 30 and 45 min (n = 104 for each resin sample). Color (ΔE*) and brightness (ΔL*) changes were analyzed by spectrophotometry using the CIE L*a*b* system and surface changes by Scanning Electron Microscopy (SEM). R1 showed more intense color changes after heat exposure than R2. ΔL* values were found to be the best parameter for evaluation of light and color change. A biphasic pattern after thermal exposure was detected, from dark brown to light white. SEM showed more intense alterations in R2 than in R1. These results indicate that the parameters observed in both resins are useful as a guide in forensic analyses.