Development Of Osteonecrosis Of The Jaw Research Articles

No increased risk of osteonecrosis of the jaw in osteoporotic patients with dental implants: a nationwide cohort study.

The occurrence of implant-associated osteonecrosis of the jaw (ONJ) has been reported in osteoporotic patients, particularly in association with bisphosphonate therapy. This study aimed to investigate the risk of implant surgery and implant presence for ONJ occurrence in osteoporotic patients longitudinally. Based on Korean National Health Information Database, subjects over the age of 65 who were diagnosed with osteoporosis between July 2014 and December 2016 were included. The implant group included subjects who had undergone dental implant surgery between January 2017 and December 2017, while the control group included those who had no history of dental implants. The primary outcome was the occurrence of ONJ, and the date of final follow-up was December 2020. A total of 332,728 subjects with osteoporosis were included in the analysis: 83,182 in the implant group and 249,546 in the control group. The risk of ONJ among those who had undergone implant surgery (risk of implant surgery-associated ONJ) was not higher than that among those without implant surgery. The risk of ONJ among those with implants (risk of implant presence-associated ONJ) was lower than that among those without implants. Even in subjects with a history of bisphosphonates, steroids, periodontitis, or tooth extraction, those who had undergone implant surgery or had implants did not have a higher ONJ risk than those who had not undergone surgery or did not have implants; rather, they showed a lower risk. The results may suggest that dental implants are not associated with an increased risk of ONJ. A further study on whether dental implants are associated with lower ONJ risk is needed. Dental implants did not increase the risk of ONJ development in osteoporotic patients, even with a history of bisphosphonates. This may suggest that the risk profiles for ONJ occurrence between selective insertion of dental implants and other dentoalveolar surgery associated with infectious conditions are different.

Efficacy and risk of osteonecrosis of the jaw for pamidronate, zoledronic acid, and denosumab in comparison to alendronate in multiple myeloma patients

Background Approximately 70% of multiple myeloma patients develop pathologic fractures. Osteoclast inhibitors can provide reduction in vertebral fractures with an increased risk of osteonecrosis of the jaw (ONJ). ONJ associated with currently used osteoclast inhibitors causes significant morbidity, often from delayed diagnosis and ineffective treatment. Methods The TriNetX Diamond Network was used to create patient cohorts for each medication: alendronate, pamidronate, zoledronic acid, and denosumab. All patients had a diagnosis of multiple myeloma as identified by International Classification of Disease–10 (ICD-10) code C90.0. Pamidronate, zoledronic acid, and denosumab were each compared to alendronate for 5-year incidence of pathologic vertebral fracture (ICD-10 M48.50XA) and development of ONJ. Results The 5-year risk of pathologic vertebral fracture was not statistically different between alendronate versus pamidronate, zoledronic acid, and denosumab. However, the 5-year risk of ONJ was significantly higher for both zoledronic acid and denosumab (relative risk 4.85 and 2.9, respectively). Conclusion This study shows that fracture reduction risk is comparable for all four treatments in multiple myeloma patients, but ONJ risk is lowest for alendronate and pamidronate. Overall, these data support the continued use of pamidronate and alendronate in multiple myeloma patients.

Lansoprazole and zoledronate delays hard tissue healing of tooth extraction sockets in dexamethasone-treated mice.

Proton pump inhibitors (PPIs) are among the most commonly prescribed medicines for the management of acid-related gastrointestinal diseases. Osteonecrosis of the jaw (ONJ) is a serious adverse event that is associated with the use of antiresorptive and antiangiogenic agents. According to previous clinical reports, the use of PPIs contributes to the pathogenesis of severe ONJ that requires surgery. Here, we investigated the effects of lansoprazole (LP) or LP in combination with zoledronate (ZOL) on ONJ development in mice. C57BL/6J mice were administered ZOL (125μg/kg intravenously, twice weekly) and/or LP (10mg/kg intraperitoneally; 3 weeks of 3 consecutive days followed by 1day off). One week after initiation of the study, the first molar was atraumatically extracted. Concurrently with ZOL administration, dexamethasone (Dex) was administered (5mg/kg intraperitoneally, twice weekly). Micro-computed tomography and histological evaluation were performed to characterize femoral structures, tooth extraction sockets, and osteonecrosis areas. The results showed that ZOL/Dex significantly increased bone mass compared to saline/Dex, while the simultaneous administration of LP and ZOL/Dex diminished the ZOL-induced enhancement of bone mass. In the alveolar bone around the tooth extraction socket, necrotic bone was significantly increased in the LP/Dex group compared to the saline/Dex group. However, no signs of more severe ONJ-like lesions were observed following combined administration of LP and ZOL/Dex, other than an increase in the number of non-attached TRAP-positive cells. Our findings in a mouse model suggest that LP use can be a risk factor for the development of ONJ.

Possible association of methotrexate use with osteonecrosis of the jaw: Systematic review

The aim was to search systematically, evaluate, and then summarize scientific literature about possible methotrexate-associated osteonecrosis of the jaw (ONJ), its signs and symptoms, diagnosis, treatment, and prognosis in adults. After registration at PROSPERO this systematic review was conducted and reported according to the PRISMA checklist. The following databases were systematically searched: MEDLINE, EBSCO, The Cochrane Central Register of Controlled Trials (Central), SCIndex, Scopus, Google Scholar and Registry of clinical studies with human participants. In total 9 studies with 14 patients were included in the review. All cases of ONJ associated with methotrexate were described in patients suffering from Rheumatoid arthritis (RA), and only about 40% of them were taking other concomitant medication described to be associated with ONJ (bisphosphonates). Both sexes were equally affected, and the patients were rather old (over 60 years if age), already taking methotrexate for more than 12 years on average. Antibiotics were ineffective in the treatment of ONJ; after stopping methotrexate, all lesions healed after several months on average; however, half of the cases required covering of the exposed bone with mucosal flap. Recurrence of the methotrexate-associated ONJ was not observed for at least two years after the lesions were healed. Methotrexate-associated ONJ is serious clinical condition that may occur in patients with RA, but given the small number of cases we have found in the literature, direct involvement of methotrexate in the development of ONJ remains elusive.

Osteonecrosis development by tooth extraction in zoledronate treated mice is inhibited by active vitamin D analogues, anti-inflammatory agents or antibiotics

Invasive dental treatment such as tooth extraction following treatment with strong anti-bone resorptive agents, including bisphosphonates and denosumab, reportedly promotes osteonecrosis of the jaw (ONJ) at the extraction site, but strategies to prevent ONJ remain unclear. Here we show that in mice, administration of either active vitamin D analogues, antibiotics or anti-inflammatory agents can prevent ONJ development induced by tooth extraction during treatment with the bisphosphonate zoledronate. Specifically, tooth extraction during treatment with zoledronate induced osteonecrosis in mice, but administration of either 1,25(OH)2D3 or ED71, both active vitamin D analogues, significantly antagonized osteonecrosis development, even under continuous zoledronate treatment. 1,25(OH)2D3 or ED71 administration also significantly inhibited osteocyte apoptosis induced by tooth extraction and bisphosphonate treatment. Administration of either active vitamin D analogue significantly inhibited elevation of serum inflammatory cytokine levels in mice in response to injection of lipopolysaccharide, an infection mimetic. Furthermore, administration of either anti-inflammatory or antibiotic reagents significantly blocked ONJ development following tooth extraction and zoledronate treatment. These findings suggest that administration of active vitamin D, anti-inflammatory agents or antibiotics could prevent ONJ development induced by tooth extraction in patients treated with zoledronate.

Gradual, but Not Sudden, Dose-Dependent Increase of ONJ Risk With Bisphosphonate Exposure: A Nationwide Cohort Study in Women With Osteoporosis.

BackgroundA causal relationship of bisphosphonate (BP) exposure with osteonecrosis of the jaw (ONJ) has been reported; however, a definite dose-dependent risk remains to be elucidated beyond current vague recommendations of 4-year oral BP for ONJ risk increase.ObjectiveTo identify the effect of bisphosphonate cumulative dose on ONJ development in women with osteoporosis.MethodsA retrospective cohort study was designed using the National Health Insurance Service—National Health Screening database of Korea. Females over the age of 50 were diagnosed with osteoporosis based on the International Classification of Diseases 10th revision (ICD-10) codes (M80, M81, and M82) with bisphosphonate prescriptions. The cumulative dose of bisphosphonate was calculated using defined daily doses (DDD) to provide an accurate BP cumulative effect on ONJ occurrence. Osteonecrosis of the jaw was identified using both ICD-10 codes and related procedure codes. The incidence rates of ONJ and hazard ratios were estimated according to the bisphosphonate cumulative dose.ResultsAmong 74,491 included subjects, 190 cases of ONJ were identified. The incidence rate substantially increased after BP cumulative dose over 1 year (25.75 for DDD < 365, which increased to 53.43 for 365 ≤ DDD < 730). Compared to subjects with a cumulative dose of DDD < 365, subjects with a cumulative dose of 365 ≤ DDD < 730 had 2.36-fold hazard for developing ONJ (p < 0.001).ConclusionA bisphosphonate cumulative dose of more than 1 year had an increased risk of ONJ development. A gradual, but not sudden, dose-dependent increase in ONJ risk with BP exposure needs to be considered in providing the optimal BP treatment duration.

Serum biomarkers for bisphosphonate-related osteonecrosis of the jaw: a prospective clinical study.

Bisphosphonate-related osteonecrosis of the jaw (ONJ) is an adverse effect of long-term bisphosphonate therapy. This study aimed to identify bone biomarkers for ONJ risk assessment and diagnosis. This prospective study included patients with histories of bisphosphonate therapy without current ONJ who were in need of dentoalveolar surgery of the jaw area. Serum levels of 12 possible bone markers, selected based on their involvement in ONJ pathogenesis, were compared between ONJ and control groups before dentoalveolar surgery (T0), at 8 postoperative weeks (T1), and at 4months after diagnosis(T2). Seventy-six patients who met the inclusion criteria were included in the study; 33 were assigned to the ONJ group, and 43 patients without ONJ signs or symptoms after dentoalveolar surgery were assigned to the control group. In the ONJ group, at both T0 and T1, the mean tartrate-resistant acid phosphatase isoform 5b (TRACP 5b) levels were significantly lower and the mean Dickkopf-related protein 1 (DKK1) levels were significantly higher than the corresponding values for the control group. Linear mixed model analysis revealed significant group effects over time for serum TRACP 5b and DKK1 after adjusting for demographic, pharmacological, and diagnostic variables. Lower serum levels of TRACP 5b under a specified cut-off value (≤ 2.899 U/L) at T0 indicated a 20.40-fold increased risk of ONJ development. Patients with abnormally low serum levels of TRACP 5b and high serum levels of DKK1 should be monitored closely before and after dentoalveolar surgery for the prevention and early diagnosis of ONJ.

Influence of prostate cancer status on the prevalence of medication-related osteonecrosis of the jaw

The aim of this study was to evaluate the risk of osteonecrosis of the jaw (ONJ) in patients with prostate cancer, particularly the relationship between prostate cancer progression and ONJ development. This single-center, retrospective, observational study included 113 patients who received zoledronic acid or denosumab for prostate cancer with bone metastasis between January 2012 and March 2020. The risk of ONJ was evaluated regarding age; antiresorptive drugs; duration of antiresorptive treatment; prostate cancer status, including castration-resistant prostate cancer (CRPC) and prostate-specific antigen level; chemotherapy; radium-223 treatment; corticosteroid treatment; diabetes mellitus; and dental extractions. Overall, 28 patients had ONJ; 10 patients received zoledronic acid and 18 patients received denosumab. Multiple logistic regression analysis demonstrated that CRPC (odds ratio=6.01; 95% confidence interval, 1.76-20.05; P=.004) and dental extractions (odds ratio=12.40; 95% confidence interval, 3.42-44.70; P < .001) were significantly associated with ONJ. In addition, antiresorptive treatment lasting more than 1 year partially mediated between CRPC and development of ONJ. CRPC and dental extraction are risk factors for developing ONJ, and antiresorptive treatment lasting more than 1 year is a partial mediator between CRPC and ONJ.

Risk of Osteonecrosis of the Jaw Under Denosumab Compared to Bisphosphonates in Patients With Osteoporosis.

Osteonecrosis of the jaw (ONJ) is a rare but serious adverse event associated with antiresorptive treatment. There is little evidence regarding the incidence of ONJ among patients with osteoporosis who are treated with denosumab versus bisphosphonates (BPs). The aim of this study was to determine the risk of ONJ in a real-world population. Subjects who underwent at least one dual-energy X-ray absorptiometry (DXA) examination were included in the osteoporosis register of the Swiss Society of Rheumatology between January 1, 2015, and September 30, 2019. Statistical analyses included incidence rates, rate ratios, and hazard ratios for ONJ, considering sequential therapies and drug holidays as covariates. Among 9956 registered patients, 3068 (89% female, median age 69 years [63 to 76]) were treated with BPs or denosumab for a cumulative duration of 11,101 and 4236 patient-years, respectively. Seventeen cases of ONJ were identified: 12 in patients receiving denosumab at the time of ONJ diagnosis and 5 in patients receiving oral or intravenous BP therapy. The diagnosis of ONJ was confirmed by independent and blinded maxillofacial surgeons, using the American Association of Oral and Maxillofacial Surgeons case definition of ONJ. The incidence of ONJ per 10,000 observed patient-years was 28.3 in patients receiving denosumab and 4.5 in patients with BP-associated ONJ, yielding a rate ratio of 6.3 (95% confidence interval [CI] 2.1 to 22.8), p < 0.001. Nine of 12 patients who developed ONJ during denosumab treatment had been pretreated with BPs, but none of the 5 patients with BP-related ONJ had previously received denosumab. The risk of ONJ was higher in patients receiving denosumab therapy compared with BPs (hazard ratio 3.49, 95% CI 1.16 to 10.47, p=0.026). Previous BP therapy before switching to denosumab may be an additional risk factor for ONJ development. © 2021 American Society for Bone and Mineral Research (ASBMR).

Tooth extraction in mice administered zoledronate increases inflammatory cytokine levels and promotes osteonecrosis of the jaw.

Osteonecrosis of the jaw (ONJ) occurring after invasive dental treatment often adversely affects patients' activities of daily living. Long-term administration of strong anti-bone resorptive agents such as bisphosphonates prior to invasive dental treatment is considered an ONJ risk factor; however, pathological mechanisms underlying ONJ development remain unclear. We developed an ONJ mouse model in which a tooth is extracted during treatment with the bisphosphonate zoledronate. We observed induction of apoptosis in osteocytes, resulting in formation of empty lacunae in jaw bones at sites of tooth extraction but not in other bones of the same mice. We also observed elevated levels of inflammatory cytokines such as TNFα, IL-6 and IL-1 in jaw bone at the extraction site relative to other sites in zoledronate-treated mice. We also report that treatment in vitro with either zoledronate or an extract from Porphyromonas gingivalis, an oral bacteria, promotes expression of inflammatory cytokines in osteoclast progenitor cells. We demonstrate that gene-targeting of either TNFα, IL-6 or IL-1 or treatment with etanercept, a TNFα inhibitor, or a neutralizing antibody against IL-6 can antagonize ONJ development caused by combined tooth extraction and zoledronate treatment. Taken together, the cytokine storm induced by invasive dental treatment under bisphosphonate treatment promotes ONJ development due to elevated levels of inflammatory cytokine-producing cells. Our work identifies novel targets potentially useful to prevent ONJ.

Incidence of and risk for osteonecrosis of the jaw in Korean osteoporosis patients treated with bisphosphonates: A nationwide cohort-study.

To estimate the incidence of osteonecrosis of the jaw (ONJ) in patients treated with bisphosphonates (BPs) and to identify clinical risk factors that increase the risk for ONJ in Korean osteoporosis patients. We used data acquired from the Korean National Health Insurance Service. Among 2,140,149 participants with osteoporosis in 2012, we selected 164,926 new BP users and 164,926 age- and sex-matched control subjects. The control group included only patients with no prescriptions for BPs between January 1, 2011, and December 31, 2016. Participants were followed for 4years. Over the 4-year follow-up period, the cumulative incidence rates of ONJ were 20.9 and 6.9 per 100,000 person-years in the BP and control groups, respectively. The BP group had an increased risk for ONJ compared to the control group after adjusting for multiple variables (hazard ratio [HR] 3.72, 95% CI 2.70-5.11). Advanced age (≥70years), comorbid diseases such as diabetes, hypertension, and rheumatoid arthritis (RA) were independent risk factors for the development of ONJ. In addition, tooth extraction (HR 9.85), gingivitis, and periodontal disease (HR 4.78) were strongly associated with ONJ. ONJ incidence was 21 per 100,000 person-years in osteoporosis patients receiving bisphosphonates. Clinical factors including advanced age, diabetes, RA, dental disease, as well as BP use were significantly associated with ONJ.

Dental consideration and management of cancer patients before initiation of IV bisphosphonates

Purpose Osteonecrosis of the jaw (ONJ) related to intravenous bisphosphonates (IVBP) is characterized by exposed necrotic bone in the maxillofacial region in patients who have received or are receiving treatment with IVBP and have no history of radiation therapy of the jaws.1 The risk of complication of using IVBP for oncologic purposes can be reduced with effective management of cancer patients. Therefore, it is imperative for practitioners to follow patient-specific guidelines for the dental management of patients who will be treated with IVBP. The purpose of this article was to provide a patient-specific, individualized approach for the dental management of patients before initiation of IVBP to prevent ONJ. This guideline will focus on 3 separate factors: the cancer, the patient, and the dentition. Methods A systematic literature review was conducted via PubMed using the following medical subject headings and terms: “bisphosphonates,” “avascular necrosis,” “bisphosphonate-related osteonecrosis of the jaw,” and “medication-related osteonecrosis of the jaw.” We then cross-referenced the same terms with the terms “multiple myeloma (MM),” “breast cancer,” “prostate cancer,” “jaw disease,” and “metastatic cancer” to identify publications that can provide evidence to develop pretreatment dental guidelines in cancer patients treated with IVBP. Articles were reviewed as a result of the PubMed literature search. The cancer types evaluated included breast cancer, prostate cancer, and MM. Relevant studies regarding patient- and dentition-related factors and their relation to IVBP treatment of the said cancers, survival, or comorbidities were evaluated. Results Upon review of articles, 137 articles met our inclusion criteria. No association was found between development of ONJ and the primary tumor site. The hazard of developing ONJ was significantly higher in patients who received zoledronic acid alone compared to those who received pamidronate alone or in combination with zoledronic acid. Our review also concluded that time of exposure to IVBP is strongly associated with development of ONJ, with exposure beyond 4 years of IVBP treatment increasing the incidence of ONJ significantly.2 Our literature search indicated that the risk of development of ONJ after IVBP treatment in cancer patient is also dose dependent, with higher doses being associated with higher risk of ONJ. This suggests that not only does the type of IVBP treatment positively correlate with the likelihood of developing ONJ, the dose and duration of IVBP therapy is also a significant factor. Our analysis identified several unique patient characteristics, including motivation, presence of a support system, socioeconomic status, nutrition, and race, which have all been found to affect the outcomes of IVBP therapy. Dental disease and available supportive dental management was found to significantly impact treatment and quality of life in this patient population. Conclusion Complications from IVBP treatment in cancer patients can have a lifelong impact on quality of life. Dentists and oral and maxillofacial surgeons can play a major role in preventing and minimizing these complications. The cancer, the patient, and the dentition should be analyzed thoroughly to assemble an effective pre-IVBP dental treatment plan. A pre-IVBP extraction-based dental treatment plan is warranted for patients with history of noncompliance, limited financial means, lack of motivation, and presence of tooth factors that decrease the prognosis of dentition. Use of zoledronic acid, IVBP for extended period of 4+ years, and dosage of 22.6 doses or higher are associated with significantly higher chance of developing ONJ and a more aggressive dental treatment (e.g., extraction vs restoration) should be utilized in treatment of these patients.

Osteonecrosis of the jaw (ONJ) in radium 223 (Ra223)-treated metastatic castration-resistant prostate cancer (mCRPC) patients (pts) with exposure to zoledronic acid and/or denosumab.

5575 Background: Bone health agents (BHA) including denosumab, a monoclonal antibody, and Zoledronic acid (ZA), a bisphosphonate, are recommended for men with CRPC and bone metastases to prevent skeletal-related complications. ONJ occurs in about 5% of patients (pts) on BHA. The incidence of ONJ in pts treated with Ra223 and BHA remains unknown, particularly in those who receive sequential treatment of BHAs. Here we describe the rate of ONJ in a real-world setting in mCRPC pts treated with Ra223 in 3 groups: 1) denosumab alone, 2) ZA alone, and 3) sequential ZA /denosumab or vice versa. Methods: A retrospective analysis of a cohort of mCRPC pts with bone metastases who received Ra223. Follow-up was until date of death or last data entry. Chart inclusion criteria included patients who received Ra223 between November 2010 to August 2018 with documentations of data points. Results: A total of 177 pts received Ra223 between 11/2010 and 8/2018. Median age 73 at 1st Ra223 (range 40-93); Median PSA 15.8- at 1st Ra223 (range 0.1-1952); Demographics-AA-10, C-130, Asian-9, unspecified-28; Median Alk Phos 95 at 1st Ra233 (range 25-1515). 93 % (164/177) received BHA. Of the 164 who received BHA, 45% (73/164) received denosumab only, 37% (61/164) received ZA only, and 18% (30/164) received sequential treatment. ONJ developed in 9.7% (16/164) of all patients on BHA. Denosumab alone caused ONJ in 7 of 73 pts (9.6%). ZA alone caused ONJ in 6 of 61 pts (9.8%). ONJ occurred in 3 of 30 pts (10%) in the sequential group. The median number of doses of BHA before development of ONJ was 10 with denosumab, 20 with ZA, and 19.5 (denosumab) and 22 (ZA) in the sequential group. Conclusions: In patients treated with Ra223 and a BHA, the rate of ONJ is 9.7%. The rate of ONJ was similar in groups treated with denosumab alone, ZA alone, and sequential treatment of ZA and denosumab However, ONJ developed more quickly in patients on denosumab. We conclude that the risk of ONJ is increased in patients treated with Ra223 and BHA. ZA or sequential therapy appears to delay time to onset of ONJ compared to denosumab. Clinicians should be mindful of the toxic synergy between Ra223 and BHA. ZA may be the preferred BHA partner with Ra223.

Primary wound closure and perioperative antibiotic therapy for prevention of bisphosphonate-related osteonecrosis of the jaw after tooth extraction.

Tooth extractions are suspected to be a major trigger for the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ). Preventive measures like perioperative antibiotic therapy and primary wound closure have been found to be effective in preventing the development of BRONJ following tooth extraction. The aim of this study was to present long-term results of a treatment protocol for patients under bisphosphonate therapy requiring tooth extraction. Between January 2008 and December 2012, 232 tooth extractions were performed in 84 patients under current or previous bisphosphonate treatment. Extractions were performed applying an atraumatic technique under prolonged intravenous antibiotic therapy. The bony edges were rounded off meticulously and the extraction sockets were covered with a mucoperiosteal flap. Out of 84 patients, two developed osteonecrosis of the jaw (ONJ), resulting in an incidence-rate of 2.4%. Both ONJ patients had received radiation therapy to the head and neck region following tooth extraction. The remaining 82 patients had uneventful healing and did not present any signs or symptoms of BRONJ during the follow-up period of 41.5 months. Tooth extractions, if performed under certain circumstances, would not seem to constitute a major risk factor for the development of BRONJ. The treatment protocol presented in this article seems to be highly effective in preventing development of ONJ after tooth extraction in patients under current or previous bisphosphonate therapy.

New factors involved in the appearance of Mandibular Osteonecrosis by Bisphosphonates in Multiple Myeloma. A multicentric study.

Osteonecrosis of the jaw (ONJ) is a complication associated with the use of bisphosphonates (BPs) in patients with multiple mieloma (MM). It is known that the previous dental procedures can precipitate the development of ONJ, but other risk factors remain unexplored. Recently, has been described the implication of other drugs in ONJ, mainly antiangiogenic treatments, but their study in the context of MM has not been performed. Objective To study the characteristics and risk factors currently implicated in the development of ONJ in patients with symptomatic MM in 13 Spanish hospitals in the last 10 years.

Vasculature submucosal changes at early stages of osteonecrosis of the jaw (ONJ).

Osteonecrosis of the jaw (ONJ), a rare, but potentially severe side effect of anti-resorptive medications, presents as exposed bone in the maxillofacial region lasting for at least 8 weeks. While clinical experience and animal models concur in finding that systemic antiresorptive treatment in conjunction with local risk factors, such as tooth extraction or dental disease may lead to ONJ development, the subclinical molecular changes that precede bone exposure remain poorly understood. The identification of these changes is not only important in understanding disease pathophysiology, but could provide potential for treatment development. Here, we evaluated the early stages of ONJ utilizing a model of experimental periodontitis (EP) in mice treated with two different types of antiresorptives, targeting potential changes in vasculature, hypoxia, oxidative stress, and apoptosis. Antiresorptive treatment in animals with EP increased levels of empty osteocytic lacunae and increased ONJ prevalence compared to Veh animals. The arteriole and venule network seen around EP areas was diminished in animals treated with antiresorptives. Higher levels of vascular endothelial growth factor A (VEGF-A) and vascular cell adhesion protein-1 (VCAM-1) were observed 1-week following EP in treated animals. Finally, levels of hypoxia, oxidative stress, and apoptosis remained high in antiresorptive treated animals with EP through the duration of the experiment. Together, our data point to subclinical vasculature organizational disturbances that subsequently affect levels of hypoxia, oxidative stress, and apoptosis in the area of developing ONJ.

Clinically Relevant Doses of Sclerostin Antibody Do Not Induce Osteonecrosis of the Jaw (ONJ) in Rats with Experimental Periodontitis.

Antiresorptive agents, such as bisphosphonates and denosumab, are frequently used for the management of osteoporosis. Indeed, both medications decrease the risk of osteoporotic fractures; however, these medications are associated with rare but potentially severe side effects, such as osteonecrosis of the jaw (ONJ). ONJ, defined as an area of exposed bone in the maxillofacial region that lasts for 8 weeks, often presents with significant pain and infection and can lead to serious complications. Interestingly, other treatments for osteoporosis have been developed, such as antibodies against the osteocyte-secreted protein, sclerostin. Sclerostin functions to inhibit the Wnt signaling cascade, leading to inhibition of bone formation. In clinical trials, a sclerostin antibody (romosozumab, Amgen Inc., UCB Brussels) increases bone formation and lowers the risk of osteoporotic fractures. However, in conjunction with increased osteoblastic activity, a reduction in bone resorption markers is observed. This antiresorptive effect raises the concern of possible ONJ development in patients treated with sclerostin antibodies. Here, utilizing ligature-induced experimental periodontitis (EP), we evaluated the effects of sclerostin inhibition on the development of ONJ-like lesions in ovariectomized rats. Beginning 8 weeks post-ovariectomy, rats were treated for 22 weeks with weekly injections of vehicle (Veh), 200 μg/kg zoledronic acid (ZA), a potent bisphosphonate at 100-fold the osteoporosis dose, or 5 mg/kg sclerostin antibody (Scl-Ab) at the osteoporotic dose. EP was initiated at week 12 and maintained for the remainder of the study. Scl-Ab treatment transiently increased serum P1NP, a bone formation marker, increased BV/TV, and decreased eroded surfaces in lumbar vertebrae. ZA-treated rats developed histologic features of ONJ, whereas Veh-treated controls did not. Scl-Ab animals lost less periodontal bone in sites with EP. However, these animals presented with no histologic signs of ONJ. In conclusion, sclerostin inhibition enhanced structural bone parameters, without inducing ONJ-like lesions, in ovariectomized rats with EP. © 2018 American Society for Bone and Mineral Research.

Current Understanding of the Pathophysiology of Osteonecrosis of the Jaw.

Osteonecrosis of the jaw (ONJ) is a rare and severe necrotic bone disease reflecting a compromise in the body's osseous healing mechanisms and unique to the craniofacial region. Antiresorptive and antiangiogenic medications have been suggested to be associated with the occurrence of ONJ; yet, the pathophysiology of this disease has not been fully elucidated. This article raises the current theories underlying the pathophysiology of ONJ. The proposed mechanisms highlight the unique localization of ONJ. The evidence-based mechanisms of ONJ pathogenesis include disturbed bone remodeling, inflammation or infection, altered immunity, soft tissue toxicity, and angiogenesis inhibition. The role of dental infections and the oral microbiome is central to ONJ, and systemic conditions such as rheumatoid arthritis and diabetes mellitus contribute through their impact on immune resiliency. Current experimental studies on mechanisms of ONJ are summarized. The definitive pathophysiology is as yet unclear. Recent studies are beginning to clarify the relative importance of the proposed mechanisms. A better understanding of osteoimmunology and the relationship of angiogenesis to the development of ONJ is needed along with detailed studies of the impact of drug holidays on the clinical condition of ONJ.

Replacing zoledronic acid with denosumab is a risk factor for developing osteonecrosis of the jaw

Intravenous zoledronic acid (ZA) is often replaced with subcutaneous denosumab in patients with bone metastatic cancer. Despite their different pharmacologic mechanisms of action, both denosumab and ZA are effective in bone metastasis but cause osteonecrosis of the jaw (ONJ) as a side effect. ZA persists in the body almost indefinitely, whereas denosumab does not persist for long periods. This study evaluated the risks of developing ONJ when replacing ZA with denosumab. In total, 161 Japanese patients administered ZA for bone metastatic cancer were enrolled in this single-center, retrospective, observational study. The risk of developing ONJ was evaluated by logistic regression analysis using the following factors: age, gender, cancer type, angiogenesis inhibitors, steroids, and replacement of ZA with denosumab. Seventeen patients (10.6%) developed ONJ. Multiple regression analysis indicated a significant difference in rate of ONJ associated with replacement of ZA with denosumab (odds ratio = 3.81; 95% confidence interval 1.04-13.97; P = .043). Replacing ZA with denosumab is a risk factor for the development of ONJ. Both binding of bisphosphonate to bone and receptor activator of nuclear factor-κ B ligand inhibition could additively increase the risk of ONJ. We bring the replacement of ZA with denosumab to the attention of clinical oncologists.

Osteomyelitis of the mandible exhibiting features of medication-related osteonecrosis in a patient with history of tocilizumab treatment

Osteomyelitis of the jaw of microbial origin manifests in bone with specific radiographic features that are key to the diagnosis. On occasion, other types of bone diseases like medication-related osteonecrosis of the jaw (MRONJ) need to be differentiated from either acute or chronic osteomyelitis. This is especially important if the medical history and physical examination are inconsistent. Apart from a thorough clinical examination, radiographic features hold an important role in the disease process which could ultimately lead to appropriate intervention. Clinician needs to be well-versed with the differential diagnosis of the bone lesions that might mimic osteomyelitis radiographically. Different medications can be attributed to osteonecrosis of the jaw (ONJ). Some monoclonal antibody medications have been attributed in the development of ONJ. Tocilizumab is a monoclonal antibody therapy used for rheumatoid arthritis. Tocilizumab-related osteonecrosis without history of bisphosphonate use has not been reported in the literature. We present a case of osteomyelitis that demonstrated similar radiographic and histological features of MRONJ in a patient treated with tocilizumab for rheumatoid arthritis without history of bisphosphonate use. Further studies are needed to assess relation between tocilizumab and ONJ.