The treatment methods for ORN and MRONJ include conservative approaches and surgical intervention. Treatment should be approached in steps according to the stage of necrotic progression. Conservative treatment is generally performed in early-stage ORN and MRONJ. Antibiotics, debridement, hyperbaric oxygen therapy, and pharmacotherapy are representative methods of conservative treatment [7,8,9]. However, if conservative treatment does not work for a long time, a surgical approach should be attempted immediately regardless of the stage. A surgical approach is essential for advanced ORN or MRONJ accompanied by fractures, osteomyelitis, oro-cutaneous fistula, or intractable pain. Radical debridement, mandibulectomy, and free flap reconstruction are commonly used as surgical methods [10,11,12,13]. The most commonly used flap for the reconstruction of the defective area after mandibulectomy is a FFF. The pedicle length of the FFF is sufficient to reach the transverse cervical vessels in the case of using the distal bone and removing the proximal bone . The mandibular defects in our patients severely damaged with ORN or MRONJ were successfully reconstructed using FFFs.
Common complications after successful reconstruction include flap loss, fistula, neck infections, and hematomas, which require additional surgery. Minor complications that do not require surgery include donor site dehiscence, infections, and partial skin graft loss . All of our patients with postoperative infections were ORN patients (patient 3 also had MRONJ). According to previous studies, the incidence of complications after the reconstruction of ORN defects with a free flap ranged from 24 to 44% [14,15,16,17]. Of the complications after ORN defect reconstruction, 13% were due to infections [15, 18, 19]. In our study, 4 of 5 patients with ORN developed infections with elevated CRP levels after surgery. However, this should be regarded as a limitation of this study due to the relatively insufficient number of patients, and it should be supplemented with studies of larger patient groups in the future.
Alam et al. reported that 6 of 33 ORN patients (18%) had wound infections as postoperative complications. Four of 6 patients with these postoperative infections did not show the growth of typical polymicrobial anaerobic oral flora in the cultures but instead grew single-organism multi-resistant gram-negative rods. The organisms were resistant to penicillin and clindamycin, the 2 typical antibiotics of choice for orally contaminated wounds. However, they did not mention what antibiotics they changed to and how they controlled the infections .
In 2021, Zhu et al. reported that 173 (79.0%) of 219 samples from the surface of local infected lesions or exudate liquid showed significant bacterial infections. The top 3 aerobic bacteria were Klebsiella pneumoniae (15.1%), Pseudomonas aeruginosa (13.54%), and Staphylococcus aureus (10.94%). Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 5.21% in the whole samples. The authors reported the antimicrobial susceptibilities of all culture-positive strains and the drug resistance rate (DRR). The drugs with almost no resistance were ticarcillin (DRR = 0.00%), ofloxacin (DRR = 0.00%), vancomycin (DRR = 0.00%), tigecycline (DRR = 0.00%), meropenem (DRR = 0.88%), and piperacillin + tazobactam (DRR = 0.88%) .
Gram-negative bacteria (Acinetobacter nosocomialis and Pseudomonas aeruginosa) and gram-positive bacteria (Enterococcus faecalis, Streptococcus mitis, and Streptococcus oralis) were detected in our patients’ pus cultures. After surgery, ceftriaxone and flomoxef were prophylactically used, and after the infection occurred, it was changed to tazoferan (piperacillin/tazobactam), vancomycin, ampicillin/sulbactam, or other antibiotics by consultation with the infectious medicine department regarding the pus culture results. Antibiotics were changed immediately or the next day according to the advice from infectious medicine. The time taken until CRP levels were reduced to less than 2mg/dL was 6 days for patient 1, 11 days for patient 2, 10 days for patient 3, and 11 days for patient 7. On average, CRP levels were controlled 9.5 days after infection and all patients who developed infections were discharged after the infection was controlled.
Empirical antibiotic use is also important, but to use antibiotics suitable for each patient, it is important to cultivate the pus or blood from the infection focus and consult with infectious medicine experts to select the appropriate antibiotics. If complication management after surgery can be thoroughly performed, FFF is a very useful method for reconstructing ORN and MRONJ defect sites.
This study is limited because it has small number of cases (7 patients). Reconstruction of mandibular defect in ORN and MRONJ using FFF is not common currently. Hence, more cases should be collected to evaluate prognosis of FFF and management of postoperative wound infections in the future.