Oral tissues are exposed to optical radiation during various dental treatments and diagnostic methods. However, adverse effects are seldom addressed. Hyperspectral imaging (HSI) and visible near-infrared reflection spectroscopy (VNIRS) were used to observe oral tissue changes in mice exposed to blue light with respect to erythema (erythema index; EI) and pigmentation (melanin index; MI). Pigmented mice (C57BL/6N; ngroup = 3) were exposed on the tongue and the abdominal skin for control or left unexposed. Irradiation was performed with an LED intended for photopolymerisation of dental materials (λpeaks: 409/460 nm) with irradiance ≈ 2 W/cm2 and radiant exposure ≈ 120 J/cm2.

The aims of this study were to improve the algorithms for calculating a transcutaneous bilirubin index (TcB), to follow the bilirubin concentrations during phototherapy and to evaluate possible changes in skin optical parameters such as pigmentation and erythema during phototherapy.