## 2 Materials and Methods  
Data on patients who received treatment between 2017 and 2022 were collected. All patients underwent surgery at the Department of Oral and Maxillofacial Surgery of the Wonju Severance Christian Hospital. Patients who underwent mandibular reconstruction without R-plates were excluded. Patients with MRONJ who underwent surgical intervention of the maxillary bones were also excluded as this study focused on the reconstruction of mandibular segmental defects. In addition, patients with ONJ due to the use of antineoplastic or antiangiogenic drugs were excluded to ensure that the ONJ was not associated with cancer or radiation therapy; therefore, we included only patients using antiresorptive drugs, such as bisphosphonates or denosumab. Thus, this retrospective observational study included patients who underwent the reconstruction of mandibular continuity defects resulting from surgical removal of the diseased bone in MRONJ using an R-plate without a bone graft. Prior to surgical intervention, these patients were diagnosed with MRONJ based on the following 2022 AAOMS criteria [11]:  
1. Current or previous treatment with antiresorptive therapy alone or in combination with immune modulators or antiangiogenic medications. 2. Exposed bone or bone that can be probed through an intraoral or extraoral fistula(e) in the maxillofacial region persisting for more than 8 weeks. 3. No history of radiation therapy to the jaws or metastatic disease to the jaws. Segmental mandibulectomy and mandibular reconstruction using an R-plate (Jeil Medical Corporation, Seoul, Republic of Korea) were performed. The bone-cutting margin was confirmed through clinical and radiographic assessments. The extent of the necrotic bone and defect was determined through panoramic radiography, cone-beam computed tomography (CBCT) (Carestream CS9300, Carestream Health, Rochester, NY, USA), and bone scanning. Intraoperatively, if a fresh blood supply and a sound bone margin could not be confirmed, the resection margin was extended. When removing the necrotic bone, the periosteum was gently handled and conserved to maximize its osteogenic potential. Following segmental mandibulectomy, the R-plate was placed. R-plates are rigid plates that are made with the intention of bridging a defect, stabilizing remaining segments, and maintaining occlusion and the facial contour. They are mainly used to fix bone blocks or vascularized bone grafts to the remaining mandible. R-plates were originally made of stainless steel, but the titanium plates are more preferable due to their biocompatibility [23]. There are several types of R-plates, but the main principle is to have one single plate of sufficient thickness and width of approximately 3 mm thick and 5 mm wide to hold the fragments in place. Every reconstruction case was held with a 2.4 mm thick titanium R-plate placed with 2.7 mm screws 5 mm above the inferior border of the mandible. Patient-specific R-plates were prepared preoperatively by pre-bending R-plates with the support of a rapid prototype model (RP model). After affixing the R-plates, they were completely covered with the conserved periosteum to utilize its osteogenic potential and prevent exposure of the surgical site. Postoperatively, analgesics and antibiotics were routinely prescribed, and the patients were regularly monitored. In the first week postoperatively, we routinely used cephalospororin and acetaminophen or ketorolac intravenously. After 2-3 weeks, according to the symptoms of patients, antibiotics and analgesics were prescribed perorally. Intermaxillary fixation and radiographic examination, including panoramic radiography and CBCT, were performed a day after the operation. A Levin tube (L-tube) diet was indicated during the first postoperative week. The L-tube is a simple small-diameter tube that is inserted through the nares to pass through the posterior orophax, down the esophagus, and into the stomach.