Osteonecrosis of the jaw after zoledronic acid and denosumab treatment

Italian position paper (SIPMO-SICMF) on medication-related osteonecrosis of the jaw (MRONJ)

OBJECTIVE

This paper aims to describe the 2023 update position paper on MRONJ developed by the Italian Societies of Oral Pathology and Medicine (SIPMO) and of Maxillofacial Surgery (SICMF).

METHODS

This is the second update following the 2013 and 2020 Italian position papers by the Expert panel, which is a representation of the two scientific societies (SIPMO and SICMF). The paper is based on an extensive analysis of the available literature from January 2003 to February 2020, and the subsequent review of literature conducted between March 2020 and December 2022 to include all new relevant published papers to confirm or modify the previous set of recommendations.

RESULTS

This position paper highlights the main issues of MRONJ on risk estimates, disease definition, diagnostic pathway, individual risk assessment, and the fundamental role of imaging in the diagnosis, classification, and management of MRONJ.

CONCLUSION

The Expert Panel confirmed the MRONJ definition, the diagnostic work-up, the clinical-radiological staging system and the prophylactic drug holiday, as recognized by SIPMO-SICMF; while, it presented novel indications regarding the categories at risk of MRONJ, the prevention strategies, and the treatment strategies associated with the therapeutic drug holiday.

A Case Report of Ibandronic Acid Induced Non-Exposed BRONJ Involving the Maxillary Sinus

Background

The aim of this case report is to present an interesting case of bisphosphonate-related osteonecrosis of the jaw, involving the maxilla and the maxillary sinus, as a result of per os administration of ibandronic acid.

Methods

A female patient, 62 years old, was referred to the Department of Dentoalveolar Surgery, Surgical Implantology and Radiology, School of Dentistry, Aristotle University of Thessaloniki, Greece, complaining about pain in the first quadrant. Her medical history revealed per os bisphosphonate administration for the past four years. Subsequently, the cone-beam computed tomography examination revealed a small sequestrum of bone, surrounded by radiolucency, in proximity with the sinus floor. The clinical examination didn't reveal any pathological clinical signs.

Results

Based on the radiological examination, a surgical approach was implemented to remove the necrotic bone, irrigate the alveolar process and the sinus with saline, and finally achieve primary closure, after which, the patient healed uneventfully. The osteonecrosis was attributed to the bisphosphonate administration.

Conclusions

Bisphosphonate-related osteonecrosis of the jaw without obvious or with minor implication of gingival tissues is a diagnostic challenge indicating an early stage of this adverse reaction. Imaging is critical for the early detection of those cases. After careful choice of the case the proper surgical intervention could be effective to eliminate a future advancement of bone destruction. The prevention of osteonecrosis of the jaw can be achieved through the provision of adequate education to dental medicine practitioners, medical doctors, and patients.

Osteonecrosis of the jaw: a rare but possible side effect in thyroid cancer patients treated with tyrosine-kinase inhibitors and bisphosphonates

Osteonecrosis of the jaw (ONJ) is a rare but very serious disease that can affect both jaws. It is defined as exposed bone in the maxillofacial region that does not heal within 8 weeks after a health care provider identification. ONJ can occur spontaneously or can be due to drugs like bisphosphonates (BPS) and anti-RANK agents, in patients with no history of external radiation therapy in the craniofacial region. Although in phase 3 trials of tyrosine kinase inhibitors (TKIs) used in thyroid cancer (TC) the ONJ was not reported among the most common side effects, several papers reported the association between ONJ and TKIs, both when they are used alone and in combination with a bisphosphonate. The appearance of an ONJ in a patient with metastatic radio-iodine refractory differentiated TC, treated with zoledronic acid and sorafenib, has put us in front of an important clinical challenge: when a ONJ occurred during TKIs treatment, it really worsens the patients' quality of life. We should consider that in the case of ONJ a TKI discontinuation becomes necessary, and this could lead to a progression of neoplastic disease. The most important aim of this review is to aware the endocrinologists/oncologists dealing with TC to pay attention to this possible side effect of BPS and TKIs, especially when they are used in association. To significantly reduced the risk of ONJ, both preventive measures before initiating not only antiresorptive therapy but also antiangiogenic agents, and regular dental examinations during the treatment should always be proposed.

The Importance of Alliance between Hematologists and Dentists: A Retrospective Study on the Development of Bisphosphonates Osteonecrosis of the Jaws (Bronj) in Multiple Myeloma Patients

(1) Background: Multiple myeloma is a rare cancer that primarily affects the bone marrow. Osteoclasts are responsible for increased bone resorption and, therefore, bone destruction. Bisphosphonates are a class of drugs that can slow down bone resorption by reducing the number and action of osteoclasts. Intravenous injections of bisphosphonates (generally Zoledronic Acid) are administered to patients affected by Multiple Myeloma, but BRONJ is described as a serious side effect. This 5-year retrospective study aims to evaluate the efficacy of appropriate dental treatment protocols prior to initiating bisphosphonate therapy to prevent the development of BRONJ. (2) Methods: A total of 99 patients with symptomatic multiple myeloma were involved in this study (41-90 years, mean age 65 years, standard deviation 5 years). The data relating to the visits were tracked using a specific server and consulting the clinical reports. The AAOMS (American Association of Oral and Maxillofacial Surgeons) position was applied for both diagnosis and treatment. A total of 79 patients were examined before the administration of bisphosphonates (group A) and 20 after (group B). (3) Results: The entire sample required dental treatment: 23.2% underwent restorative therapy, 8% endodontic treatments, 44.4% tooth extractions. Periodontal disease was present in 41.4% of the patients. No osteonecrosis was observed in the first group, whereas BRONJ was found in five patients of the second one (25%) and two patients (10%) showed osteosclerotic areas under investigation [OR 0.026 (CI 0.0027 to 0.2454)]. (4) Conclusions: In the literature, there are no precise data about the prevalence of BRONJ. Despite the limitation of the present study, we point out that dental treatment before the treatment with intravenous bisphosphonates can help in reducing the incidence of BRONJ and good dental status is necessary for BRONJ prevention.

Osteonecrosis of the Jaw Beyond Bisphosphonates: Are There Any Unknown Local Risk Factors?

INTRODUCTION

Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) is a complication of intravenous (IV) BP therapy. BP therapy locally affects the dentoalveolar area, while systemic effects are associated with parenteral/IV BP use. Despite numerous publications, the pathogenesis of BRONJ is not fully understood, as only some patients receiving IV BPs develop BRONJ.

PURPOSE

Can impaired bone remodeling (found in aseptic-ischemic osteonecrosis of the jaw [AIOJ], bone marrow defects [BMD], or fatty-degenerative osteonecrosis of the jaw [FDOJ]) represent a risk factor for BRONJ formation?

PATIENTS AND METHODS

A literature search clarified the relationship between AIOJ, BMD, FDOJ, and BRONJ, in which common characteristics related to signal cascades, pathohistology, and diagnostics are explored and compared. A case description examining non-exposed BRONJ is presented.

DISCUSSION

Non-exposed BRONJ variants may represent one stage in undetected BMD development, and progression to BRONJ results from BPs.

CONCLUSION

Unresolved wound healing at extraction sites, where wisdom teeth have been removed for example, may contribute to the pathogenesis of BRONJ. With IV BP administration, persisting AIOJ/BMD/FDOJ areas may be behind BRONJ development. Therapeutic recommendations include IV BP administration following AIOJ/BMD/FDOJ diagnosis and surgical removal of ischemic areas. BPs should not be regarded as the only cause of osteonecrosis.

CT imaging features of antiresorptive agent-related osteonecrosis of the jaw/medication-related osteonecrosis of the jaw

OBJECTIVES

Antiresorptive agent-related osteonecrosis of the jaw (ARONJ)/medication-related osteonecrosis of the jaw (MRONJ) include both bisphosphonate-related osteonecrosis of jaw (BRONJ) and denosumab-related osteonecrosis of jaw (DRONJ). The purpose of this study is to study radiological characteristics of ARONJ/MRONJ. These imaging features may serve as one useful aid for assessing ARONJ/MRONJ.

METHODS

CT scans of 74 Japanese patients, who were clinically diagnosed by inclusion criteria of ARONJ/MRONJ, obtained between April 1, 2011 and September 30, 2016, were evaluated. We investigated the CT imaging features of ARONJ/MRONJ, and clarified radiological differentiation between BRONJ and DRONJ, BRONJ due to oral bisphosphonate administration and due to intravenous bisphosphonate administration, BRONJ with respective kinds of medication, BRONJ with long-term administration and short-term administration, BRONJ with each clinical staging respectively. Fisher's exact test, χ² test, Student's t-test and analysis of variance were performed in the statistical analyses.

RESULTS

Unilateral maxillary sinusitis was detected in all patients with upper ARONJ/MRONJ (100%). DRONJ showed large sequestrum more frequently than BRONJ (3/4, 75 vs 3/35, 8.6%, p < 0.05). DRONJ showed periosteal reaction more frequently than BRONJ (4/10, 40 vs 7/65, 10.1%, p < 0.05). Patients of BRONJ resulting from intravenous bisphosphonate administration showed larger and more frequent buccolingual cortical bone perforations than BRONJ resulting from oral bisphosphonate administration (7/8, 87.5 vs 11/30, 36.7%, p < 0.05). There was no significant correlation between CT findings and respective kinds of medication, long/short-term administration, clinical stages of BRONJ.

CONCLUSIONS

ARONJ/MRONJ has characteristic CT image findings which could be useful for its assessment.

Does CBCT alter the diagnostic thinking efficacy, management and prognosis of patients with suspected Stage 0 medication-related osteonecrosis of the jaws?

OBJECTIVES

To evaluate the impact of cone beam CT (CBCT) in the diagnostic thinking efficacy, management and prognosis of patients with suspected Stage 0 medication-related osteonecrosis of the jaw (MRONJ).

METHODS

For 15 patients with suspected Stage 0 MRONJ, clinical photographs, a panoramic radiograph and selected CBCT sections were identified. 13 oral surgeons reviewed the material and answered 10 questions in two different sessions. First session included clinical photographs and panoramic radiographs, while second session also included CBCT images. Questions (Qs) referred to dental disease and bone abnormalities (Qs 1, 2 and 3), differential diagnosis (Qs 4 and 5), patient management (Qs 6 and 7) and prognosis (Qs 8 and 9). Q 10 queried indication (first session) and usefulness (second session) of CBCT images.

RESULTS

Qs 2, 3, 5, 7 and 9 scores increased between sessions, with statistical differences for Qs 2, 3, 5 and 7 (<0.05). Patients 2, 8 and 11 showed a significant increase in the average score of all Qs between sessions, while scores for patient 10 nearly reached statistical significance (p = 0.055). For Q 10, 57.4% of answers reported that CBCT was needed (first session) and was beneficial (second session).

CONCLUSIONS

CBCT had a significant impact in differential diagnosis and management of patients with suspected Stage 0 MRONJ.

Osteonecrosis of the Jaws (ONJ) after Bisphosphonate Treatment in Patients with Multiple Myeloma: Decreasing ONJ Incidence after Adoption of Preventive Measures

Bisphosphonates (BPs) are administered to Multiple Myeloma (MM) patients with bone lytic lesion. Osteonecrosis of the Jaw (ONJ) is a complication reported since 2003 in patients treated with intravenous (IV) BPs such as zoledronic acid and pamidronate, with 6%–26.3% frequency in early literature series, before some preventive measures were recommended. We evaluated the occurrence of ONJ with and without dental preventive measures in MM patients treated with BPs in our centre between 1996 and 2015. Since 2005, MM patients (already under treatment or before treatment) underwent a baseline mouth assessment (dental visit, Rx orthopantomography, and eventual tooth avulsion or dental care if necessary) and were followed by a multidisciplinary team. We reviewed the charts of 119 MM patients receiving IV BPs, classified into 3 groups: (a) “historic group” (21 patients who had started BP treatment in years before the awareness of ONJ); (b) “screening group” (20 patients starting BPs without baseline evaluation); and (c) “prevention group” (78 patients starting therapy only after baseline preventive assessment and eventual dental care measures). ONJ was observed in 3/21 patients (14.2%) from group a, in 2/20 patients (10%) from group b, and in no patients from group c (0%). Notably, the median number of IV BP administrations decreased after 2005. Our data confirmed a meaningful reduction of ONJ risk in MM patients treated with BPs if preventive measures are applied. Both implementation of prevention measures and reduction of cumulative doses of IV BPs could have contributed to a decreased incidence of ONJ.

Mevalonates restore zoledronic acid-induced osteoclastogenesis inhibition

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is likely to be caused by continuous imperfection of bone healing after surgical treatments in patients with long-term administration of nitrogen-containing bisphosphonates (NBPs). NBPs inhibit osteoclastic bone resorption by impairing the mevalonic acid sterol pathway in osteoclasts. Thus, we hypothesized that exogenous mevalonic acid metabolites restore the inhibitory effects of NBPs on osteoclastogenesis and bone remodeling. To clarify the effects of mevalonic acid metabolites, especially geranylgeranyl pyrophosphate (GGPP) and geranylgeranyl transferase substrate geranylgeranyl acid (GGOH), we examined the effects of zoledronic acid with or without GGOH or GGPP on osteoclast differentiation, multinucleation, and bone mineral deposition in tooth-extracted sockets. Zoledronic acid decreased the number of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells derived from mouse osteoclast precursors treated with receptor activator of nuclear factor-κB ligand and macrophage colony-stimulating factor. Zoledronic acid simultaneously suppressed not only the expressions of osteoclastic differentiation-related molecules such as TRAP, cathepsin K, calcitonin receptor, and vacuolar H-ATPase but also those of multinucleation-related molecules such as dendrocyte-expressed 7 transmembrane proteins and osteoclast stimulatory transmembrane protein. Treatment with GGOH or GGPP, but not farnesyl acid, restored the zoledronic acid-inhibited number of TRAP-positive multinuclear cells together with the expressions of these molecules. Although intraperitoneal administration of zoledronic acid and lipopolysaccharide into mice appeared to induce BRONJ-like lesions with empty bone lacunae and decreased mineral deposition in tooth-extracted socket, both GGOH and GGPP partially restored the inhibitory effects on zoledronic acid-related mineral deposition. These results suggest the potential of mevalonic acid metabolites as therapeutic agents for BRONJ.

Osteochemonecrosis: an overview

Osteonecrosis of the jaw to a certain extent has been with us for many years. But recently the advent of various medications such as bisphosphonates, VEGF inhibitors, tyrosine kinase inhibitors and humanized antibodies to osteoclastic action have resulted in thousands of cases. While the bisphosphonates continue to be the most common medication associated with osteochemonecrosis antibodies such as denosumab which irreversibly act on osteoclastic action are also being reported. This narrative review will serve as an update with a focus on some of the histopathologic features discussed and reviewed. Perhaps even more uncommonly seen in past reports a discussion of features possibly observed while grossing specimens will be discussed. At the end of this report is hoped that the pathologist will have a better understanding of the historical features, clinical settings, gross examination features as well as histopathologic features associated with osteochemonecrosis.

Epidemiology, clinical manifestations, risk reduction and treatment strategies of jaw osteonecrosis in cancer patients exposed to antiresorptive agents

ABSTRACT: Osteonecrosis of the jaws (ONJ) is an adverse side event of bisphosphonates and denosumab, antiresorptive agents that effectively reduce the incidence of skeletal-related events in patients with metastatic bone cancer and multiple myeloma. Available data suggest that 0–27.5% of individuals exposed to antiresorptive agents can develop ONJ. There is increasing evidence that avoidance of surgical trauma and infection to the jawbones can minimize the risk of ONJ, but there are still a significant number of individuals who develop ONJ in the absence of these risk factors. Bone necrosis is almost irreversible and there is no definitive cure for ONJ with the exclusion, in certain cases, of surgical resection. However, most ONJ individuals are affected by advanced incurable cancer and are often managed with minimally invasive nonsurgical interventions in order to control jawbone infections and painful symptoms. This article summarizes current knowledge of ONJ epidemiology, manifestations, risk-reduction and therapeutic strategies. Further research is needed in order to determine individual predisposition to ONJ and clarify the effectiveness of available treatments.

Stage 0 osteonecrosis of the jaw in a patient on denosumab

Osteonecrosis of the jaws (ONJ) is a complex disease involving multiple tissue and cell-type responses to wound healing or infection. AAOMS defines bisphosphonate related ONJ (BRONJ) as exposed, necrotic bone in the maxillofacial region that has persisted for more than 8 weeks in a patient with current or previous antiresorptive treatment, without a history of radiation therapy to the jaws. Since the first reported ONJ cases in 2003 and 2004, there has been little advancement in understanding the etiology and pathophysiology of ONJ. Many hypotheses have been proposed, including bisphosphonate (BP) toxicity to oral epithelium, altered wound healing after tooth extraction, high turnover of the mandible and maxilla, oral biofilm formation, infection and inflammation, and suppression of angiogenesis and bone turnover. The current classification system of ONJ involves stages 0 to 3 and is based on patient clinical presentation. This report describes a case of stage 0 ONJ in a patient on denosumab and indicates the full-spectrum similarities between BP- and denosumab-associated ONJ clinically, radiographically, and histologically.

Clinical study evaluating the effect of bevacizumab on the severity of zoledronic acid-related osteonecrosis of the jaw in cancer patients

This study aimed to evaluate the effect of bevacizumab (BVZ) on the severity of osteonecrosis of the jaw (ONJ) in a cohort of cancer patients treated with intravenous zoledronic acid (ZA). We reviewed 42 oncologic patients with ONJ between 2007 and 2010. Only patients with solids tumors and who had received ZA were included. Data analyses included age, sex, underlying disease, ZA and BVZ dosages, dental history and ONJ characteristics. Of the 42 ONJ patients treated with ZA, 10 also received BVZ. In the 10 ZA/BVZ patients, the mean duration of ZA treatment at the time of ONJ diagnosis was 12.4 months (±6.8), compared to 22.9 months (±4.8) in the 32 patients who received ZA only (p<0.05). Cox's model analysis of the delay to ONJ diagnosis confirmed the impact of BVZ on ONJ diagnosis. In the ZA/BVZ-treated group, 7 (70%) patients developed spontaneous osteonecrosis. Multiple logistic regression analysis showed that ZA/BVZ is associated with increased risk of developing spontaneous ONJ (OR 6.07; 95% CI, [1.3-28.2], p<0.05). And finally, the number of ONJ lesions was increased in the ZA/BVZ-treated group compared to the ZA group (p<0.01). Other clinical conditions as type of tumor (prostate, breast…), cancer severity or other chemotherapy drugs also could be involved in ONJ evolution. However, this study demonstrates for the first time the potential negative influence of BVZ on the incidence and severity of ONJ in patients receiving ZA. Within the study limits, our results suggest that combination ZA/BVZ treatment may possibly predispose to the development of spontaneous and earlier ONJ.

Risks for jaw osteonecrosis drastically increases after 2 years of bisphosphonate therapy

SUBJECTS

This study consisted of 191 patients older than 40 years with osteonecrosis of the jaw (ONJ) drawn from dental practices in the geographic locations of 3 practice-based research networks (PBRNs). Control patients (n = 573) enrolled were individuals older than 40 years without prior history of ONJ. Three control patients were matched with each ONJ case. The ONJ cases originated from primary, secondary, and tertiary care centers. For each ONJ case diagnosed at a primary care center, the 3 matched controls were selected from the same primary care center. However, controls for cases obtained from secondary or tertiary care centers were selected when possible from the general dental practice that referred the case or from another practice in the same geographic area.

KEY RISK/STUDY FACTOR

The key risk factor in this study was bisphosphonate therapy.

MAIN OUTCOME MEASURE

The main outcome measure was ONJ. The definition of ONJ was maxillary or mandibular exposed bone of any size that clinically appeared necrotic, without regard for duration or cause. Therefore, all types of jaw osteonecrotic lesions were included in this study; but patients were limited to those diagnosed with onset of ONJ after January 1, 2003, without prior history of facial trauma or sickle cell disease.

MAIN RESULTS

The results indicate that 83% of cases and 15% of controls received bisphosphonate therapy for a mean duration (standard error) of 5.6 (0.7) and 4.2 (0.6) years, respectively. Therapy with either intravenous or oral bisphosphonates was highly predictive of ONJ; however, intravenous bisphosphonates (odds ratio [OR] = 299.5; 95% confidence interval [CI] = 70.0- 1282.7) were more associated with ONJ than oral bisphosphonates (OR = 9.8; 95% CI = 5.3- 18.1). Risk of developing ONJ existed within the first 2 years and increased fourfold after 2 years of bisphosphonate use (P < .0001).

CONCLUSIONS

The authors concluded that ONJ is causally linked to both intravenous and oral bisphosphonate use, and risk of ONJ escalates tremendously after 2 years of bisphosphonate therapy. The authors also concluded that oral suppuration and dental extractions are independent ONJ risk factors.

Decreasing frequency of osteonecrosis of the jaw in cancer and myeloma patients treated with bisphosphonates: the experience of the oncology network of piedmont and aosta valley (north-Western Italy)

Background. Data concerning frequency of Osteonecrosis of Jaws (ONJ) are mostly based on single center experiences. Patients and Methods. Since 2005 a multidisciplinary study group collected data of cases of ONJ in patients treated with Bisphosphonates (BP) and observed in oncology and hematology centers of a regional network. Results. By December 2008, 221 cases were registered. We report details of 200 cases, identified after cross-checking reports from centres of medical oncology, haematology, and oral care. Primary neoplasm was breast cancer (39%), myeloma (32%), prostate cancer (16%), and other types of cancer (8%). In about 50% of the cases a history of dental extraction was present. Zoledronic acid was administered (alone or with other BP) to 178 patients (89%). Median time from first infusion to ONJ diagnosis was 21.0 (zoledronic acid only) and 39.0 months (pamidronate only). The number of ONJ cases per year was 3 in 2003, 21 in 2004, 58 in 2005, 60 in 2006, 37 in 2007, and 21 in 2008. Conclusion. The number of new ONJ cases in cancer and myeloma patients increased until 2006 and then reduced. The possible reasons of this trend (introduction of zoledronic acid; increase of ONJ awareness; diffusion of preventive dental measures; late modifications of BP prescription) are herein discussed.

Denosumab osteonecrosis of the mandible: a new entity? A case report

In the treatment of osteoporosis, M. Kahler and bone metastases from prostate and breast cancer bisphosphonates play a major role. Not all patients respond well to bisphosphonate treatment. Since a few years adverse effects of these drugs have been reported. A new drug, denosumab, a fully human monoclonal antibody to RANKL, has recently been developed. This case reports a 74-year-old male patient with a medical history of diabetes mellitus, angina pectoris, coronary bypasses, hypertension, and prostate cancer with multiple metastases to lymph nodes, bone and lungs. The prostate cancer was treated according to the protocol. But he was never treated with bisphosphonates. Instead he was included in a phase III randomized double blind multicenter trial, testing the efficacy of denosumab compared to zoledronic acid in the treatment of bone metastases of hormone resistant prostate cancer. Only 7 months after start of denosumab infectious symptoms developed, followed by infestation of the mandible. Despite surgical treatment fistula and exposed bone remained. This case illustrates that use of denosumab can lead to a type of osteonecrosis resembling bisphosphonate related osteonecrosis of the jaws.

Osteonecrosis of the jaw onset times are based on the route of bisphosphonate therapy

PURPOSE

Osteonecrosis of the jaw (ONJ) has been reported to be associated with patients receiving bisphosphonate (BP) therapy. There are many reports that suggest that the time of exposure to BPs is a significant risk factor for ONJ and that the greatest risk occurs after dentoalveolar surgery. The aim of this study was to retrospectively investigate the duration of BP therapy and related events before the onset of ONJ based on an intravenous (IV) or oral route of administration.

MATERIALS AND METHODS

We conducted a retrospective cohort study of patients referred to our institution to identify the onset of ONJ based on the exposure to BP therapy and associated triggers (ie, dentoalveolar surgery or spontaneous occurrence) based on the route of BP administration. Demographic data (ie, age, gender, and race), medical diagnosis related to BP therapy, and information as to whether the BP therapy was continued at the time of ONJ diagnosis were also collected.

RESULTS

We reviewed the records for 114 patients with a history of ONJ. We divided patient cohorts by route of BP administration, with 76 patients having a history of IV BP therapy and 38 patients having a history of oral BP therapy. The overall onset of ONJ was earlier in the IV BP group (median, 3 years) compared with the oral BP group (median, 5 years). There was no statistical difference in the duration to occurrence of ONJ associated with dental extraction compared with spontaneous occurrence for both the IV and oral BP groups.

CONCLUSIONS

The median onset of ONJ for patients undergoing IV BP therapy occurs earlier than the median onset for patients undergoing oral BP therapy, and there was no difference in onset occurring spontaneously and after dental extraction. The significance of these findings suggests that patients who receive IV BP therapy should be closely evaluated after the initiation of BP therapy. The lack of evidence suggesting greater onset after dental extraction may provide clinical support for dentoalveolar surgery that is indicated for patients with a history of BP therapy. Research focusing on the clinical circumstances and physiologic events during early antiresorptive therapy may provide insight as to the critical risk factors.

Dexrazoxane shows cytoprotective effects in zoledronic acid-treated human cells in vitro and in the rabbit tibia model in vivo

INTRODUCTION

Bisphosphonates are important and effective drugs in oncology and osteoporosis therapy. They accumulate in the bone matrix becoming released and active by bone resorption. This leads to effective inhibition of tumor cells and bone degradation. A side effect of bisphosphonates similar to other drugs like denosumab is osteonecrosis of the jaws (ONJ). This problem mostly occurs after tooth extraction. We studied the cytoprotectant dexrazoxane known from anthracycline chemotherapy for cytoprotection in nitrogen-containing bisphosphonate treated cells and in the rabbit tibia model to evaluate a possible value in ONJ management.

MATERIALS & METHODS

Human osteoblasts (HOB) P2 cells and Human ginigiva fibroblasts (HGF) P2 cells were treated with zoledronic acid (50 μmol/L) and the cytoprotectant dexrazoxane (600 μmol/L). Analysis included cell viability testing with MTT assay and morphology analysis using CellTracker™ Green CMFDA. A biomaterial carrier (Bio-Oss Collagen) was implanted in the rabbit tibia of 6 female chinchilla bastard rabbits on both sides with drill hole defects (d: 3.2mm). Implants were loaded with 25 nmol zoledronic acid, with and without 300 nmol dexrazoxane and unloaded in a control group. Analysis included histological examination of undecalcified samples with toloudine blue staining after 10 days.

RESULTS

In vitro experiments showed a significantly higher MTT activity in cells treated with zoledronic acid together with dexrazoxane compared to the same cells treated with the bisphosphonate alone in t-test (HOB: p=0.0003; HGF: p below 0.0001) and one-way ANOVA. Cell morphology changes were consistent with these results. In vivo results showed newly formed bone trabeculae directly growing towards the implanted hydroxylapatite particles and cortical bone interface resorption activities in the control and the experimental group only.

CONCLUSION

The study suggests a possible value of this patented technology for ONJ therapy and prevention with local or systemic application.

Non-exposed bisphosphonate-related osteonecrosis of the jaw: a critical assessment of current definition, staging, and treatment guidelines

Non-exposed bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a newly reported complication arising from bisphosphonate therapy that presents with atypical symptoms and no apparent mucosal fenestration or exposure of necrotic bone. The clinical observation of the presence of necrotic bone underneath normal epithelial coverage was not conclusive for the diagnosis of BRONJ based on current guidelines established by the American Association of Oral and Maxillofacial Surgeons (AAOMS) and the American Society for Bone and Mineral Research (ASBMR), which specify the presence of clinically exposed necrotic bone for more than 8 weeks. Hence, the purpose of this review is to critically assess the current guidelines for diagnosis and management of BRONJ and propose a modified staging system and treatment guidelines to properly address the non-exposed variant of BRONJ lesions.