Aim: A clinical case is described in order to focus on a little known but relevant aesthetic drawback potentially related to bone substitutes. Material and Methods: Case Report: After a minimally traumatic extraction of a first maxillary right molar, MHA (Sint- Life) particulate was inserted into the socket for bone preservation. Surgical procedure and healing process were uneventful. Two months later, buccal soft tissues displayed an asymptomatic bluish discoloration. Six years later, the pigmentation was still present and the radiographic evaluation showed residual biomaterial particles. In order to comprehend the origin of the mucosal alteration, an histomorphological evaluation of soft and hard tissues was performed. Histological examination confirmed the presence of residual MHA particles, mainly in direct contact with bone tissue, but partly embedded into the subepithelial fibrotic chorion. There was no melanosis or melanocytic hyperplasia in the epithelium. Mild inflammatory infiltrate was observed, without haemosiderin deposits.
Results: These findings suggest that MHA represents the source of discoloration. An explanation can be found in the Tyndall effect, which refers to the fact that different wavelengths of light do not scatter depending on size of substances they encounter: longer redder wavelengths can penetrate more deeply into the soft tissues than shorter blue wavelength before reflecting out. So the light reflecting from tissue over the biomaterial contains less red light than blue. Conclusion: The potential appearance of permanent mucosal discoloration represents a relevant drawback for oral cavity, especially for those areas with clear aesthetic demands. More investigations are needed in order to confirm the present observations.
