Medication-related osteonecrosis of the jaw: A literature review and update.

Since the initial description of medication-related osteonecrosis of the jaw (MRONJ) almost two decades ago, the potential pathophysiology and risk factors have been elaborated on in many investigations and guidelines. However, the definitive pathophysiology based on scientific evidence remains lacking. Consequently, the optimal clinical treatment and prevention strategies for MRONJ have not been established. Despite their different mechanisms of action, many drugs, including bisphosphonates, denosumab, angiogenesis inhibitors, and other medications, have been reported to be associated with MRONJ lesions in cancer and osteoporosis patients. Importantly, MRONJ occurs predominantly in the jawbones and other craniofacial regions, but not in the appendicular skeleton. In this up-to-date review, the currently available information and theories regarding MRONJ are presented from both clinical and basic science perspectives. The definition and epidemiology of MRONJ, triggering medication, and histopathology are comprehensively summarized. The immunopathology and the potential pathophysiology based on immune cells such as neutrophils, T and B cells, macrophages, dendritic cells, and natural killer cells are also discussed. In addition, antiangiogenesis, soft tissue toxicity, necrotic bone, osteocyte death, and single-nucleotide polymorphisms are examined. Moreover, other possible mechanisms of MRONJ development are considered based on the unique embryological characteristics, different cell behaviors between jawbones and appendicular skeleton, unique anatomical structures, and sustained bacterial exposure in the oral cavity as a basis for MRONJ site specificity. Based on the literature review, it was concluded that multiple factors may contribute to the development of MRONJ, although which one is the key player triggering MRONJ in the craniofacial region remains unknown.

Periosteal reaction of medication-related osteonecrosis of the jaw (MRONJ): clinical significance and changes during conservative therapy.

PURPOSE: We previously reported that the periosteal reaction (PR) in medication-related osteonecrosis of the jaw (MRONJ) is a poor prognostic factor in surgical cases, but it is not clear how PR changes during conservative therapy. The purpose of this retrospective study was to compare computed tomography (CT) findings at the first visit and during follow-up visits in MRONJ patients subjected to conservative therapy and to investigate factors associated with the exacerbation of PR during conservative therapy. METHODS: Sixteen patients with MRONJ of the lower jaw who underwent conservative therapy and experienced a PR on CT images at the first visit and underwent CT examination again after 6 months or more were enrolled in the study. Clinical features and CT findings (extent of osteolytic lesion, extent of PR, type of PR, and changes during conservative treatment) were investigated. RESULTS: On the second CT scan, the osteolytic lesion improved in 4 patients, had not changed in 5, and deteriorated in 7, whereas the PR improved in 5 patients, had not changed in 4, and deteriorated in 7 patients. PR was significantly deteriorated in patients who continued to receive antiresorptive agents during conservative treatment and in patients with deteriorated osteolytic lesions. CONCLUSION: PR in MRONJ often expands during conservative therapy and the PR type progresses from the attached type to the gap type, and the irregular type, but discontinuation of antiresorptive agent may improve PR as well as osteolytic lesions.

Awareness of Complications of Dental Treatment in Patients Treated with Drugs Affecting the Immune System : A Nationwide Questionnaire Survey of Dental Practitioners in Japan.

The aim of this study was to investigate the awareness and experience, among dental practitioners, of adverse events resulting from dental treatment of patients undergoing therapy with drugs that affect the immune system [angiogenesis inhibitors, biological agents, immunosuppressants, and disease-modifying anti-rheumatic drugs (DMARDs)]. For this purpose, a nationwide questionnaire survey was conducted. Questionnaires were sent to 2,050 dentists, of which 206 (10.1%) were completed and returned. The results showed that most dentists were aware of complications associated with dental treatment of patients treated with drugs that affect the immune system, and about half had actually experienced such complications. Delayed wound healing, osteonecrosis of the jaw (ONJ), and postoperative infections were reported. Whereas approximately 50% of dentists did not discontinue the drugs during dental treatment, about 18% did. During temporary drug discontinuation, some patients experienced aggravation of the primary disease, such as worsening of rheumatism, growth of tumors, and rejection reactions of transplanted organs. As for medical cooperation, only less than half of the dentists were asked for oral hygiene management by a physician prior to starting the drug treatment. Prospective studies are needed because evidence for dental treatments in patients treated with these drugs remains limited.

Does inflammatory dental disease affect the development of medication-related osteonecrosis of the jaw in patients using high-dose bone-modifying agents?

OBJECTIVES: High-dose bone-modifying agents (BMAs), such as bisphosphonates and denosumab, are essential for the treatment of cancer patients with bone metastases. The incidence of medication-related osteonecrosis of the jaw (MRONJ) is increasing. Inflammatory dental diseases could lead to MRONJ, and hence, they should be managed appropriately. Tooth extractions are commonly advised to prevent dental inflammation; however, the accurate indications for tooth extractions before starting BMA therapy have not been established. Hence, we assessed teeth with inflammatory dental diseases to identify indicators for prophylactic extraction before starting BMA therapy. MATERIALS AND METHODS: We included 745 teeth with inflammatory dental diseases of 212 cancer patients on high-dose BMA therapy. We assessed the relationship between inflammatory dental disease and risk of MRONJ development. Multivariate Cox regression analysis was used for statistical analysis. The cumulative occurrence rate of MRONJ was calculated using the Kaplan-Meier method. RESULTS: MRONJ occurred in 43 of 745 teeth. Teeth characteristics significantly correlated with MRONJ occurrence were mandible (p = 0.009), molar region (p = 0.005), radiopaque changes in bone surrounding the root on orthopantograms obtained at patients' first visits (p < 0.001), and tooth extractions after starting BMA therapy (p < 0.001). CONCLUSIONS: Radiopaque changes in bone surrounding the root are an important radiographic finding that indicates the need for prophylactic tooth extractions before starting BMA therapy. CLINICAL RELEVANCE: Our results suggest that the prophylactic extraction of teeth with radiopaque changes in bone surrounding the root before starting BMA therapy could prevent the onset of MRONJ.

Awareness among patient at risk of developing Medication Related Osteonecrosis of the Jaw (MRONJ) - A primary prevention strategy.

The quality of life, in itself, in cancer patients or in osteoporotic individuals, without even considering the side effects of the medication in the first place, has a considerable negative impact on the clinical outcome. The Medication Related Osteonecrosis of the Jaw (MRONJ), in the maxillofacial region, although rare, needs to be addressed with the prime importance. One of the key components of any given preventive treatment strategy is to, create awareness about the medication related unwanted effects, among health care professionals and patients. OBJECTIVE: This study is aimed to explore and assess the awareness level among dental patients about MRONJ, the risk factors, and the high-risk category (who are prone to develop MRONJ). MATERIAL AND METHODS: This is a prospective interviewer administered research electronic data capture (REDCap) survey. The sample included 68 patients, who are currently taking or will be taking Bisphosphonate (BP), and/or Denosumab, and anti-Angiogenic agent. Data have been analyzed using IBM SPSS software. RESULTS: Sixty-eight patients (18 males and 50 females), participated in this study. Only 23 subjects (33.82%) were aware about the MRONJ. Females were more aware about the complications than males. The awareness among the subjects with education at college level appears to be higher than the subjects having education less than high school level. Even though, a dental check- up, is mandatory, prior to starting these medications, to see if any dental treatment is required, only slightly more than half of the patients (54.72%) had a dental checkup. CONCLUSION: This is a novel study in the Middle- East, used to assess awareness about the MRONJ including three type of related medications. Low awareness of MRONJ is alarming. The results of the study will help to initiate the process of providing the education materials, about the side effects and importance of oral hygiene maintenance, giving priority to improve the quality of life in such patients. Awareness of patients regarding the complications must be an important part of health care practice guidelines.

Quantitation and distribution of metallic elements in sequestra of medication-related osteonecrosis of jaw (MRONJ) using inductively coupled plasma atomic emission spectroscopy and synchrotron radiation X-ray fluorescence analysis.

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse effect of antiresorptive agents like bisphosphonates. Abnormal concentrations of various trace metallic elements contained in bone minerals have been associated with MRONJ. In this study, we focused on trace metallic elements contained in the MRONJ sequestrum; their content and distribution were compared to those in osteomyelitis and non-inflammatory bones using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and synchrotron radiation X-ray fluorescence analysis (SR-XRF). On ICP-AES analyses, various trace elements (Co, Cr, Cu, Fe, K, Mg, Ni, Sb, Ti, V, Pb) were significantly more in MRONJ sequestra than non-inflammatory bones. The Cu content was significantly higher in MRONJ sequestra than osteomyelitis and non-inflammatory bones. The Cu content in MRONJ sequestra was high even after decalcification. Additionally, Cu was distributed along the trabecular structures in decalcified MRONJ specimens, as observed using SR-XRF analysis. Therefore, this study was indicative of the characteristic behavior of Cu in MRONJ.

Dental treatments, tooth extractions, and osteonecrosis of the jaw in Japanese patients with rheumatoid arthritis: results from the IORRA cohort study.

This study aimed to evaluate dental treatments, tooth extractions, and osteonecrosis of the jaw (ONJ) in Japanese patients with rheumatoid arthritis (RA). Patients with RA enrolled in our cohort completed self-administered questionnaires, which included questions regarding their dental treatments, tooth extractions by dentists during the past 6 months, and past history of ONJ. The history of ONJ was validated with the patients' medical records. Logistic regression was used to determine the association of variables with dental treatments and tooth extractions during the past 6 months. Among 5695 Japanese patients with RA who responded to the questionnaires (mean age, 61.0 years; 85.6 % female), 2323 patients (40.8 %) and 378 patients (6.6 %) reported having had dental treatments and tooth extractions performed by a dentist within the past 6 months, respectively. In multivariate models, advanced age was significantly (P < 0.0001) associated with both dental treatments and tooth extractions during the prior 6-month period, and ever smoking was significantly (P = 0.023) correlated with tooth extractions during that time. Among patients who reported a history of ONJ, we confirmed five cases of ONJ with patient medical records. The prevalence of ONJ was 0.094 % among all RA patients and 0.26 % among female RA patients ≥65 years of age (n = 1888). Our data suggest that more than a few Japanese patients with RA have dental complications that require care by dentists, and that Japanese rheumatologists and dentists should cooperate to improve dental health in patients with RA.

Radiological manifestations and clinical findings of patients with oncologic and osteoporotic medication-related osteonecrosis of the jaw.

Medication-related osteonecrosis of the jaw (MRONJ) poses a challenging form of osteomyelitis in patients undergoing antiresorptive therapies in contrast to conventional osteomyelitis. This study aimed to compare the clinical and radiological features of MRONJ between patients receiving low-dose medications for osteoporosis and those receiving high-dose medications for oncologic purposes. The clinical, panoramic radiographic, and computed tomography data of 159 patients with MRONJ (osteoporotic group, n = 120; oncologic group, n = 39) who developed the condition after using antiresorptive medications for the management of osteoporosis or bone malignancy were analyzed. The osteoporotic group was older (75.8 vs. 60.4 years, p < 0.01) and had a longer duration of medication usage than the oncologic group (58.1 vs. 28.0 months, p < 0.01). Pus discharge and swelling were more common in the osteoporotic group (p < 0.05), whereas bone exposure was more frequent in the oncologic group (p < 0.01). The mandibular cortical index (MCI) in panoramic radiographs was higher in the osteoporotic group (p < 0.01). The mean sequestra size was larger in the oncologic group than in the osteoporotic group (15.3 vs. 10.6 mm, p < 0.05). The cured rate was significantly higher in the osteoporotic group (66.3% vs. 33.3%, p < 0.01). Oncologic MRONJ exhibited distinct clinical findings including rapid disease onset, fewer purulent signs, and lower cure rates than osteoporotic MRONJ. Radiological features such as sequestrum size on CT scan, and MCI values on panoramic radiographs, may aid in differentiating MRONJ in osteoporotic and oncologic patients.

Treatment of medication-related osteonecrosis of the jaw with cell therapy.

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) poses a significant challenge considering the absence of a "gold standard" treatment. Cell-based therapy and tissue engineering offer promising therapeutic alternatives. This study aimed to harness the regenerative properties of adipose-tissue stromal vascular fraction (AT-SVF) and leukocyte-platelet-rich fibrin (L-PRF) for MRONJ treatment. AT-SVF contains mesenchymal stromal cells (MSC) and endothelial progenitor cells (EPC), which promote bone formation, while the L-PRF scaffold can serve as a three-dimensional scaffold for the AT-SVF and support tissue healing through growth factor release. Materials and methods: The protocol involved applying autologous AT-SVF within an L-PRF matrix following surgical debridement. Age, gender, body mass index, comorbidities, underlying oncological condition, prescribed antiresorptive treatment: BP or DMB, antiresorptive treatment duration, antiresorptive treatment potential discontinuation, number of MRONJ lesion, MRONJ location, MRONJ stage, MRONJ trigger factor were assessed for each patient. Patients underwent the procedure and were monitored for a minimum of 6 months based on clinical, biological and medical imaging criteria. Results: Nine patients, with a total of ten MRONJ lesions, participated in the study. Six patients were female, and three were male, with a mean age of 68 ± 8 years. Four patients had multiple myeloma (MM), three had metastatic breast cancer, and two had metastatic prostate cancer. Seven MRONJ cases were classified as stage II, and three were classified as stage III. Soft tissue completely healed within a month after treatment in nine cases, with no clinical improvement observed in the remaining case. During follow-up, no sign of MRONJ recurrence was observed. Tridimensional medical imaging revealed bone healing 6 months after the surgical procedure. Immunophenotyping confirmed the presence of MSC and EPC in the AT-SVF: 12,6 ± 4,5% CD31+, 20.5 ± 7,8% CD34+, 34,4 ± 7,3% CD146+ and 54,6 ± 7,4% CD45+. Conclusion: This prospective study introduces a potential new treatment approach for MRONJ using autologous AT-SVF within an L-PRF scaffold. Our results are encouraging and suggest the need for further investigation with a larger patient cohort to better understand the underlying mechanisms.

Geranylgeraniol (GGOH), incorporated into a bone cement pellet promotes osteoclast function and healing in a model of medication-related osteonecrosis of the jaw.

Introduction: There is no cause -based treatment for Medication-Related Osteonecrosis of the Jaw (MRONJ). MRONJ is a morbid condition including exposed, infected bone and mandibular fractures in osteoporotic individuals and metastatic cancers patients treated with nitrogen containing bisphosphonates (NBP). NBPs inhibit farnesyl diphosphate synthase (FDPS) in the mevalonate pathway, depriving osteoclasts and other bone cells of small GTPases necessary for their function and survival. We test the hypothesis that geranylgeraniol (GGOH),a metabolite downstream of FDPS, when incorporated into a bone cement pellet, enhances osteoclast function and promotes local bone healing in in vitro and in a proven animal model of MRONJ. Methods: 3H labelled GGOH (2 mM) was incorporated into a Hydroset bone cement pellet and release from the cement was assessed over time. To assess the effect on bone cell function, the GGOH-loaded cement was placed in a porous filter above cultured osteoclasts treated with bisphosphonate and the effect on osteoclast survival and function were measured. In a pilot study the effect of GGOH on osteotomy microstructure was measured in a rat model of MRONJ using a split mouth design. Results: The release of GGOH from bone cement increased osteoclast survival/metabolic activity, and promoted resorption of the calcified substrate. In vivo released GGOH limited the effects of the bisphosphonate and promoted healing. In an animal pilot study, GGOH from the infused cement carrier stabilizes bone structure and restores the ability of osteoclasts to remodel. Conclusion: These initial findings point to GGOH in a bone cement carrier as a useful therapeutic approach to prevent or mitigate the pathogenesis of MRONJ.

Usefulness of quantitative bone SPECT/CT for evaluating medication-related osteonecrosis of the jaw treatment response.

OBJECTIVE: For assessment of therapeutic response in medication-related osteonecrosis of the jaw (MRONJ) cases, the clinical usefulness of quantitative bone single-photon computed tomography-computed tomography (SPECT/CT) results was investigated. MATERIALS AND METHODS: Sixteen patients (18 lesions) with a clinical diagnosis of MRONJ underwent bone SPECT/CT scanning before and during/after anti-inflammatory therapy given for 3 or more months. The GI-BONE software package was used to determine standard uptake values (SUVs), including maximum (SUVmax), peak (SUVpeak), and mean (SUVmean), and metabolic bone volume (MBV) and also total bone uptake (TBU). In both responders (downstage) and non-responders (upstage or no change), differences in quantitative values between the first and second SPECT/CT examinations were analyzed using a Wilcoxon test. RESULTS: Following therapy, significant reductions in SUVmax, SUVpeak, SUVmean, MBV and TBU values for 11 lesions were noted in the responders after therapy (p = 0.003, p = 0.006, p = 0.004, p = 0.003, and p = 0.002, respectively). On the other hand, those for the seven lesions in the non-responder group were not significantly different (p = 0.17, p = 0.16, p = 0.26, p = 0.96, and p = 0.12, respectively). Results for SUVmax change showed sensitivity and specificity values of 45.5% and 85.7%, respectively, for differentiating responders from non-responders, with - 37.3% the optimal cutoff value. Those for MBV change were 72.7 and 85.7%, respectively, with - 29.4% the optimal cutoff value. Those for TBU change were 81.8% and 85.7%, respectively, with - 36.3% the optimal cutoff value. CONCLUSION: The present findings showed that therapeutic response in MRONJ cases could be determined by use of quantitative SUV, MBV, and TBU values based on bone SPECT/CT findings.

MicroRNA in medication related osteonecrosis of the jaw: a review.

Medication related osteonecrosis of the jaw (MRONJ) is a condition caused by inhibition of the osteoclast activity by the anti-resorptive and anti-angiogenic drugs. Clinically, there is an exposure of the necrotic bone or a fistula which fails to heal for more than 8 weeks. The adjacent soft tissue is inflamed and pus may be present as a result of the secondary infection. To date, there is no consistent biomarker that could aid in the diagnosis of the disease. The aim of this review was to explore the literature on the microRNAs (miRNAs) related to medication related osteonecrosis of the jaw, and to describe the role of each miRNA as a biomarker for diagnostic purpose and others. Its role in therapeutics was also searched. It was shown that miR-21, miR-23a, and miR-145 were significantly different in a study involving multiple myeloma patients as well as in a human-animal study while miR-23a-3p and miR-23b-3p were 12- to 14-fold upregulated compared to the control group in an animal study. The role of the microRNAs in these studies were for diagnostics, predictor of progress of MRONJ and pathogenesis. Apart from its potential diagnostics role, microRNAs have been shown to be bone resorption regulator through miR-21, miR-23a and miR-145 and this could be utilized therapeutically.

Osimertinib: Another medication related to osteonecrosis of the jaws? A case report and literature review.

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is an oral complication in cancer patients being treated with either antiresorptives, mainly denosumab and bisphosphonates, or antiangiogenic drugs. Osimertinib is a third-generation epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) for the treatment of patients with EGFR T790M advanced non-small-cell lung cancer (NSCLC). TKI-induced osteonecrosis of the jaw has been reported in recent years, but these cases almost occur in combination with bisphosphonates, and the data on MRONJ associated to osimertinib is scarce. Case report: We reported a case of MRONJ associated only with osimertinib. A 69-year-old female patient with NSCLC developed MRONJ after 4 years of treatment with osimertinib. Six months ago, she felt persistent pain and swelling in the right maxilla. After 3 months of pain, her dentist extracted one tooth in the right maxilla under local anesthesia. We examined her gingiva and found fistula and pus spillage. A digital volume tomography scan revealed sequestrum. The patient underwent surgical debridement of the necrotic bone under general anesthesia and administered intravenous antibiotics at the hospital. Histopathological analysis of the bone biopsy revealed a diagnosis of MRONJ. Conclusion: This report provides evidence that osimertinib monotherapy can cause MRNOJ, and has a contribution to explore the formation mechanism of MRONJ. For those patients who take osimertinib, routine oral examinations and monitoring should be performed before and during treatment, as well as prompt closure of wounds and antibiotic treatment to avoid infection after invasive oral surgery such as tooth extraction.

Usefulness of quantitative bone SPECT/CT for medication-related osteonecrosis of the jaw in clinical settings.

OBJECTIVE: This study was conducted to investigate the clinical utility of quantitative bone single-photon computed tomography-computed tomography (SPECT/CT) for detection and classification for medication-related osteonecrosis of the jaw (MRONJ). MATERIALS AND METHODS: Fifty-nine patients (69 lesions) clinically diagnosed as MRONJ by four specialists of Japanese Society of Oral Surgery according to the AAOMS diagnostic criteria and who underwent bone SPECT/CT were enrolled. One reader determined standard uptake values (SUVs), including maximum (SUVmax), peak (SUVpeak), and mean (SUVmean), as well as metabolic bone volume (MBV), representing total volume above threshold, and total bone uptake (TBU), calculated as MBV × SUVmean, using the GI-BONE software package. One-way repeated-measures analysis of variance and subsequent post hoc analysis were employed to compare quantitative values between clinical stages. To check reproducibility of values, another reader calculated these quantitative values. RESULTS: Mean SUVmax values for stage 0 (n = 21), 1 (n = 13), 2 (n = 25), and 3 (n = 10) were 5.82 ± 3.20, 5.46 ± 3.79, 8.16 ± 3.93, and 10.57 ± 8.43, respectively, while values for MBV were 9.52 ± 6.33, 11.36 ± 7.32, 12.4 ± 8.21, and 17.84 ± 16.94, respectively, and for TBU were 40.60 ± 46.97, 53.70 ± 77.26, 62.37 ± 42.91, and 102.01 ± 74.52, respectively. There were significant differences for SUVmax, SUVpeak, and SUVmean between clinical stages (p = 0.024, p = 0.027, p = 0.039, respectively). Subsequent post hoc analysis showed that SUVmax and SUVpeak of stage 3 were significantly higher than those of stage 0 (p = 0.046, 0.045, respectively). MBV and TBU showed a tendency to increase with increased stage, though differences between stages were not significant (p = 0.15, p = 0.053, respectively). Little differences of mean SUVmax, SUVpeak, SUVmean, MBV, and TBU between two readers were observed (- 3.10%, - 0.26%, - 4.24%%, 0.69%, and - 3.42%, respectively). The intraclass correlation coefficients (ICCs) of SUVmax, SUVpeak, SUVmean, MBV, and TBU were 0.985, 0.990, 0.980, 0.994, and 0.994, respectively (almost perfect for all values). CONCLUSION: As objective and reliable indicators, SUVmax and SUVpeak derived from quantitative bone SPECT/CT results are useful for detection of early status disease, as well as staging in MRONJ patients.

Age Related Immunosenescence Epstein-Barr Virus-positive Mucocutaneous Ulcer of the Palate Mimicking Medication-related Osteonecrosis of the Jaw.

Epstein-Barr virus (EBV) -positive mucocutaneous ulcer (EBVMCU) was first described as a lymphoproliferative disorder in 2010. In recent years, EBVMCU has been reported in the field of oral surgery. On the other hand, medication-related osteonecrosis of the jaw (MRONJ) is an osteomyelitis that occurs in patients receiving antiresorptive agents including bisphosphonates (BP) and/or denosumab developing with bacterial infections such as dental diseases and mucositis. MRONJ caused by EBVMCU in the elderly has not been reported. Here, we report a rare case of MRONJ caused by EBVMCU in the elderly. The patient, an 82-year-old woman, had received BP for more than 2 years. An ulcerative lesion was found in the palatal mucosa; biopsy performed from the site confirmed the diagnosis of EBVMCU. At follow-up, the lesion disappeared spontaneously. At the 6-month follow-up, bone formation was observed at the site of the lesion, and the sequestrum was removed. At the 12-month follow-up healing of the EBVMCU region was seen indicating a good prognosis.

Lineage-associated connexin 43 expression in bisphosphonate-exposed rat bones.

Expression of signaling proteins in bone cells depends on their embryological mesoderm-derived (e.g. tibia) or cranial neural crest (CNC)-derived (e.g. jaw) origin. Connexin 43 (Cx43) is a gap junction protein that plays an essential role in the mode of action of bisphosphonates (BP). This study aimed to investigate Cx43 expression and the influence of BP application on mesoderm- and CNC-derived bone. Using a rat model, molar extraction and tibia osteotomy with (Group 4) or without (Group 3) previous BP application was performed. Untreated (Group 1) and animals selectively treated with BPs (Group 2) served as controls. Cx43 expression was immunohistochemically determined 12 and 16 weeks postoperatively via a labeling index. Cx43 expression in CNC-derived bone was significantly higher compared with mesodermal bone. BP application decreased Cx43 expression; however, detected expression levels were still higher in jawbone (Group 2 tibia vs jaw: 5.83 ± 5.06 vs 23.52 ± 6.42; p = 0.007). During bone healing after surgical intervention (Group 3) there were no expression differences between tibia and jawbone. BP treatment prior to surgery resulted in significantly lower Cx43 expression in CNC-derived compared with tibia bone (Group 4 tibia vs jaw: 56.84 ± 15.57 vs 16.40 ± 5.66; p < 0.01). Increased Cx43 expression in jaw compared with tibia bone is in line with their embryological origins. A significant Cx43 suppression in jawbone after BP application and surgery might contribute to the selectively altered osseous turnover and development of MRONJ in CNC-derived bone.

Medication-related osteonecrosis of the mandible: an unusual presentation and treatment.

A 71-year-old woman was referred to the clinic with extensive medication-related osteonecrosis of the jaw (MRONJ) involving the mandible. She had received 7 years of zoledronate therapy. On cone beam computed tomography, the MRONJ presented as a large sequestrum spanning from the left to the right condylar process, surrounded by thick sub-periosteal bone. The sequestrum was excised via an intraoral approach, leaving the newly formed sub-periosteal bone as a neo-mandible. The patient recovered well from the operation and was discharged 5 days after surgery. She healed completely without complications. This case report presents an alternative surgical treatment that may be considered if there is clinically stable sub-periosteal bone surrounding extensive MRONJ.

Mandibulectomy Reconstruction with Pectoralis Major Island Flap Associated with Primary Reconstruction Plate for Mandibular Medication-Related Osteonecrosis.

A bimaxillary edentulous male patient, aged 67 years, diagnosed with prostate cancer who underwent intravenous bisphosphonates treatment (zoledronic acid) for about one year presented with pain in the anterior mandibular arch, with exposed necrotic bone, and was diagnosed with stage 2 medication-related osteonecrosis of the jaw (MRONJ). MRONJ is the development of bone necrosis in the oral cavity as an adverse reaction in patients treated with antiresorptive and antiangiogenic medication, without radiation therapy to the head and neck. This persistent bone necrosis does not always respond to standard treatments. The reconstruction technique with pectoralis major flap, at a distance, associated with the primary reconstruction plate, was an effective treatment modality for the treatment of large osteonecrosis noncompliant with conservatory treatments. Through this technique, the morpho-functionality of the jaw can be restored almost completely.

Various Therapeutic Methods for the Treatment of Medication-Related Osteonecrosis of the Jaw (MRONJ) and Their Limitations: A Narrative Review on New Molecular and Cellular Therapeutic Approaches.

Medication-related osteonecrosis of the jaw (MRONJ) is one of the most interesting diseases in the field of maxillofacial surgery. In addition to bisphosphonates, the use of antiresorptive and antiangiogenic agents is known to be the leading cause. However, the exact pathogenesis of MRONJ has not been established, and various hypotheses have been proposed, such as oxidative stress-related theory. As a result, a definitive treatment protocol for MRONJ has not been identified, while various therapeutic approaches are applied to manage patients with MRONJ. Although the surgical approach to treat osteomyelitis of the jaw has been proven to be most effective, there are limitations, such as recurrence and delayed healing. Many studies and clinical trials are being conducted to develop another effective therapeutic modality. The use of some materials, including platelet concentrates and bone morphogenetic proteins, showed a positive effect on MRONJ. Among them, teriparatide is currently the most promising material, and it has shown encouraging results when applied to patients with MRONJ. Furthermore, cell therapy using mesenchymal stem cells showed promising results, and it can be the new therapeutic approach for the treatment of MRONJ. This review presents various treatment methods for MRONJ and their limitations while investigating newly developed and researched molecular and cellular therapeutic approaches along with a literature review.

New Perspective for Soft Tissue Closure in Medication-Related Osteonecrosis of the Jaw (MRONJ) Using Barbed Sutures.

The aim of this study was to compare the effectiveness of barbed versus smooth sutures for soft tissue closure of exposed jawbone sites in medication-related osteonecrosis of the jaw (MRONJ) patients. Exposed necrotic jawbone sites surgically managed by intraoral soft tissue closure were evaluated. Either barbed sutures (Stratafix™ or V-Loc™) together with Prolene® or Vicryl® sutures were used. We estimated the effect of barbed sutures (BS) with Prolene® compared to smooth sutures (Vicryl®) on the hazard rate of intraoral soft tissue dehiscence using a multivariate Cox regression model within a target trial framework, adjusting for relevant confounders. In total, 306 operations were performed in 188 sites. In the primary analysis 182 sites without prior surgery were included. Of these, 113 sites developed a dehiscence during follow-up. 84 sites were operated using BS and Prolene®. A total of 222 sites were operated with Vicryl® (control group). In the BS group, the median time to event (i.e., dehiscence) was 148 days (interquartile range (IQR), 42-449 days) compared to 15 days (IQR, 12-52 days) in the control group. The hazard rate of developing intraoral dehiscence was 0.03 times (95%-confidence interval (CI): 0.01; 0.14, p < 0.001) lower for BS patients compared to the control group. Within the limits of a retrospective study, BS showed a high success rate and are therefore recommended for soft tissue closure of exposed jawbone sites in MRONJ patients. Additional studies are warranted to further evaluate this novel application of BS.