Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse reaction to antiresorptive or antiangiogenic therapy that leads to severe pain, bone exposure, and pus discharge from a fistula at advanced stages (Nicolatou-Galitis et al., 2019; Ruggiero et al., 2022). The most frequent causes of MRONJ are antiresorptive agents, such as bisphosphonates and denosumab, which are used for patients with bone-consuming malignant diseases, bone metastasis of malignant diseases, or osteoporosis (Hayashida et al., 2017; Ruggiero et al., 2022). Although the mechanism of osteonecrosis caused by antiresorptive agents is not fully understood, the number of patients with MRONJ is expected to increase over the next decade. This trend suggests that MRONJ treatment will become a challenging issue in oral and maxillofacial surgery (Hallmer et al., 2018; Alzahrani et al., 2022).

Several research groups have reported that, for patients with MRONJ (at both early and advanced stages), surgical treatment results in better healing outcomes compared with nonsurgical conservative treatment (Hayashida et al., 2017; El-Rabbany et al., 2019; Ristow et al., 2018). In their 2022 position paper, the American Association of Oral and Maxillofacial Surgeons (AAOMS) redefined the clinical characteristics of MRONJ and provided more support for the early and extensive surgical treatment of patients with MRONJ at all stages (Ruggiero et al., 2022). The main purposes of the surgical treatment of MRONJ are to achieve complete mucosal healing of the exposed bone and at least down-staging for symptom relief (Ruggiero et al., 2022).

The complete removal of necrotic bone and infected soft tissue, along with closure of the wound, is crucial to minimizing the risks of MRONJ relapse and progression (El-Rabbany et al., 2019; Ristow et al., 2018; Suyama et al., 2024). However, soft-tissue closure using only a mucoperiosteal flap has demonstrated unstable and poor mucosal integrity in patients with advanced MRONJ, with low success rates ranging from 18.7% to 54.5% (Klingelhöffer et al., 2016; Lemound et al., 2018; Ahrenbog et al., 2020; Huang et al., 2024).

A variety of techniques for covering soft-tissue defects have introduced new possibilities and opportunities for providing healthy, stable tissue, which promotes mucosal healing and vascularization of the debrided bone. These techniques include well-vascularized local flaps (Eckardt et al., 2011; Berrone et al., 2015; Rotaru et al., 2015; Lemound et al., 2018; Ristow et al., 2018; Aljohani et al., 2019; Ahrenbog et al., 2020; Jose et al., 2022; Huang et al., 2024) and free flaps (Mücke et al., 2016; Caldroney et al., 2017), depending on the size and location of the defects as well as the patient's overall health condition.

For patients with stage 2 or stage 3 maxillomandibular MRONJ, our group has previously explained technical methods using the buccal fat flap (BFF), nasolabial flap (NFL), facial artery musculomucosal flap (FAMM-F), and submental island flap (SIF) to cover and close the defects after removal of the necrotic bone (Myoken and Fujita, 2018, 2020, 2021, 2022, 2023; Fujita et al., 2020). The present study was conducted to evaluate the success rates of various soft-tissue closure techniques, including BFF, NLF, FAMM-F, and SIF, following bone surgery in stage 2 and 3 MRONJ patients. This evaluation aimed to provide appropriate indications and limitations for each method.