Implication of the definition of carious dentine Scanning electron microscopy has mode it possible to demonstrate that the dental tissue underlying o carious lesion has on outer demineralised and infected area, and an inner sclerotic layer due to introtubular mineral deposition. In order to eradicate the bacterial infection while minimizing the surgical destruction of the potentially-reminerizable underlying tissue, the current guidelines indicate that only the outer layers of the carious dentine should be removed, on objective that con be more easily reached if the border between the demineralised and the sclerotic areas is clearly identified. Given the availability of new (including laser-based) technology the present study represents a first attempt to define morphological criteria for the treatment of hard dental tissue.