Colour stability of dental restorative materials submitted to conditions of burial and drowning, for forensic purposes

Abstract

The aim of this study was to evaluate the effect of earth and water on the colour stability of tooth-coloured dental restorative materials: composite resin (CR) and glass ionomer cement (GIC). Aiming to distinguish between one and another tooth-coloured material and to estimate the period in which they could be submitted to the factors earth and water, the proposed method may contribute to the proceedings of human identification of victims of burial and submersion in water. Forty bovine incisors were prepared (6 x 6 x 2mm) and restored with CR FiltekTM Z250 XT (3M ESPETM) and GIC KetacTM Fil Plus (3M ESPETM). After initial colour read-outs (VITATM Easyshade spectrophotometer), the samples were separated into two groups (n=10), according to the conditions to which they were submitted: simulations of burying and submersion in water, for periods of 1, 3, 6 and 12 months, when new read-outs were taken. The values of colour change (ΔE, ΔL*, Δa*, and Δb*) were subjected to 3-way ANOVA statistical analysis, repeated measures, Bonferroni (p<.05), and it was verified that both factors produced colour changes in the restorative materials, which were higher for glass ionomer cement (p<.05) after 12 months of burial, and 6 months of submersion in water. The authors concluded that the analysis of colour change in the material contributed to the forensic odontology casework depending on the time during which the victim was submitted to the condition of burial or submersion in water.