Clinical Differences in Autofluorescence Between Viable and Nonvital Bone: A Case Report With Histopathologic Evaluation Performed on Medication-Related Osteonecrosis of the Jaws

Medication-related osteonecrosis of the jaws (MRONJ) is an adverse side effect of several drug therapies, including bisphosphonates (BPs). Osteonecrosis of the jaw specifically related to BP therapy is usually referred to using the acronym BRONJ. However, no consensus has yet been reached regarding the most appropriate management of BRONJ. The greatest success rates have been recorded with surgical removal of necrotic bone. In particular, erbium:yttrium-aluminum-garnet (Er:YAG) laser-assisted surgery has shown significantly better results than conventional surgical approaches. According to a position paper reported by the American Association of Oral and Maxillofacial Surgeons in 2007, the identification of necrotic bone margins during osteonecrosis removal can be very difficult. In 2015, a review of treatment perspectives for MRONJ reported that both surgical debridement and resection cannot be standardized owing to the lack of guidance to define the necrotic margins. Recently, the use of autofluorescence (AF) of the bone as a possible suitable guide to visualize necrotic bone during surgical debridement or resection was proposed. It seems that vital bone could be highlighted by its very strong AF. In contrast, necrotic bone loses AF and, thus, appears much darker. The molecular sources of the phenomenon of AF are the specific amino acids of the collagen molecules that show AF when irradiated by ultraviolet or blue light. The use of AF as an intraoperative diagnostic tool is entirely new in the management of MRONJ, although it has been used for several years in other fields (eg, intervertebral disc surgery). The aim of the present report was to describe a case of mandibular BRONJ treated with a new surgical approach performed with an Er:YAG laser and guided by AF. The histopathologic evaluation of the removed hypofluorescent bone block and hyperfluorescent surrounding bone has also been reported in detail.