## 3 Discussion  
The present report describes a digital workflow for necrotic bone resection and the prevention of mandibular fracture secondary to MRONJ surgical intervention through virtual surgical planning and customized CAD/CAM reconstruction plates where otherwise, to date, few studies are available. The results of the present case series indicate that the applied protocol allowed successful resection and the adaptability of the reconstruction plates to both patients. Considering the significant impact of MRONJ on patients' quality of life, it is necessary to maintain good clinical practices for primary and secondary prevention. Primary prevention is focused on eliminating, or at least reducing, oral and dental risk factors in the pre-, per-, and post-medication phases [20]. Secondary prevention aims at early diagnosis in order to increase treatment success rates [20], and in this sense it is of paramount importance to obtain a complete medical history of the patient. A challenging aspect of MRONJ therapy is the delineation of necrotic bone to be resected. Several authors have suggested different approaches, such as the resection of bleeding bone and fluorescence-guided surgery; however, it is difficult to achieve a clear demarcation of necrotic bone [21; 22; 23; 24]. In the cases presented in this study, the marginal resection of necrotic bone was planned with preoperative Computer Tomography scans (Figures 1c and 2a). VSP and tridimensional modelling were useful in determining the extension of resection and allowed the precise replication of resection margins for the patient using the CAD/CAM surgical guides. Moreover, VSP helped to preserve the integrity of the inferior alveolar nerve and to safely determine the dimensions of the unaffected bone to be spared in the inferior border of the mandible. In both cases, 6 mm of reminiscent bone were calculated, implying a significant risk of mandible fracture during or after the procedure given the patients' ages and comorbidities. Mandible fracture has a significant impact on quality of life, given its association with pain and the inability to eat normally [13]. Moreover, managing fractures in elderly patients poses additional challenges, including poor bone quality, decreased osteogenesis, and operative risks, such as bleeding and anesthetic complications, with increased post-operative morbidity and mortality [25; 26]. Therefore, in these two cases, patient-specific reconstruction plates were planned and applied as means of avoiding mandible fracture while minimizing operative time by eliminating intraoperative plate bending procedures. These advantages were previously reported by other authors, who confirmed that pre-bent plates decrease surgical time and increase reconstruction accuracy [16]. Moreover, concerns over fatigue fracture might be dismissed considering that mandibular reconstruction CAD/CAM plates avoid the use of excessive bending procedures that weaken the plates [15; 18; 27]. Nevertheless, the potential disadvantages of surgical interventions, including anesthetic risks, the possible exposure of plates in the absence of keratinized tissue, or overheating during drilling procedures, should also be accounted for when planning these interventions. A combined intraoral-transbuccal approach was used. In the first case, placing the surgical guide intraorally was more cumbersome due to its excessive thickness. Pre-drilling hole extensions were intraoperatively reduced with a bur to allow its use. In the second case, we designed a two-component surgical guide with reduced thickness for improved ease of insertion and fixation. We recommend using the latter design when an intraoral approach is to be followed. The surgeries were performed in an outpatient fashion, under general anesthesia and perioperative antibiotic prophylaxis.