This in vivo and in vitro study investigated the influence of pulpal vitality on the optical properties of teeth over a 1-month period.

We monitored two specific areas (2-mm-thick pure enamel and 3-mm-thick enamel-dentine complex) in 10 teeth against two backgrounds (white and black) using a calibrated reflectance spectrophotometer at the following time points: before extraction (T0); immediately after extraction (T1); at 1-day post-extraction (T2); at 1-week post-extraction (T3); and 1-month post-extraction (T4). We recorded tooth colour based on the Commission Internationale d'Eclairage L*a*b* model and translucency and analysed these characteristics over time using analysis of variance.

The 2-mm-thick pure enamel area showed significant changes (p > 0.05) in L*, a* and b* values between before and 1 month after extraction (T0-T4). Translucency was detectable between (T0-T3) and (T0-T4). The 3-mm-thick enamel-dentine complex also exhibited significant differences (p > 0.05) in L*, a* and b* values within (T0-T4). Translucency value changes significantly (p > 0.05) within the first day (T0-T2) and (T0-T3). CIEDE 2000 DE values revealed no statistically significant differences (p < 0.05) in colour between the T0 L*a*b* measures and all the subsequent measures at times T1, T2, T3 and T4.

Within the limitations of this study, we conclude that the optical characteristics (i.e. colour and translucency) of teeth change after extraction.

The results help understanding the precise moment when the colour of extracted tooth changes to identify optimum time to use a tooth for scientific investigation and determine whether it is necessary to extract pulp tissue beforehand.