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.

[Thoughts on the prevention, clinical diagnosis and treatment of osteonecrosis of the jaw and future research directions].

With the progress and development of society, osteonecrosis of the jaw has appeared some new features and new problems in oral clinical work. The prevention, early diagnosis, and early treatments of osteonecrosis of the jaw are of great significance. This article describes the current clinical diagnosis and treatment status of osteoradionecrosis of the jaw and medication-related osteonecrosis of the jaw, and puts forward some thoughts on the prevention, clinical diagnosis and treatment and future research direction of osteonecrosis of the jaw.

Osteonecrosis de los maxilares asociada a medicamentos: revisión de la literatura y propuesta para la prevención y manejo / Osteonecrosis of the jaws

Medication-related osteonecrosis of the jaw is a disease where there is necrotic bone exposed or that can be explored by means of a fistula in the maxillofacial region. It has been associated with the use Biphosphonates and denosumab for osteoporosis. Although its etiology is unclear, it may be related to a decrease in bone turnover produced by these drugs, rendering the bone more prone to generate cell necrosis during invasive dental procedures, especially in the posterior region of the jaw. There is no consensus about the prevention and treatment of this condition. The aim of this paper is to present a review of the literature with the main characteristics of osteonecrosis of the jaws associated with drugs, together with a proposal for prevention and treatment for these patients.

[Current evidence-based approaches and international guidelines in primary and secondary prevention strategies of medication-related osteonecrosis of the jaws]. / Aktualitások a gyógyszer okozta állcsontelhalás primer és szekunder prevenciójának stratégiájában az evidenciák és a nemzetközi ajánlások tükrében.

Introduction: The presumably multifactorial pathomechanisms of medication-related osteonecrosis of the jaws have not been fully elucidated so far. Management of this rare but serious side effect is a real challenge and requires a multidisciplinary approach. Aim: The aim of the authors was to take stock of our present knowledge about the pathogenesis, risk factors, clinical manifestations and the possibilities of prevention and treatment in the medication-related osteonecrosis of the jaws. In addition, the available international guidelines are compared and the evidence-based, stage-specific conservative and adjuvant therapeutic approaches are also reviewed, having regard to special aspects of medical and dental care. Method: In the last 5 years - due to the increasing number of disorder-oriented database - the number of available systematic reviews, recommendations and meta-analyses has escalated significantly which we reviewed and compared. Results: Since the last Position Paper published by the taskforce of the American Association of Oral and Maxillofacial Surgeons, novel pharmacological groups with the potential to induce osteonecrosis have come in the clinical scope, further elaborating the nomenclature of the disease and further specifying patient groups. The sphere of patients at risk has broadened and novel patient groups (rheumatologic-osteological, immunosuppressed, transplanted or oncological patients treated with monoclonal antibody, known as 'target therapy') are expected to develop this serious side effect. Conclusion: Although a number of issues are still open regarding the treatment of the disorder, evidence-based, individualized, stage-adapted therapeutic approaches have replaced the previous empirical treatment. Orv Hetil. 2020; 161(6): 214-223.

[Osteonecrosis of the jaws]. / Osteonecrosis de los maxilares asociada a medicamentos: revisión de la literatura y propuesta para la prevención y manejo.

Medication-related osteonecrosis of the jaw is a disease where there is necrotic bone exposed or that can be explored by means of a fistula in the maxillofacial region. It has been associated with the use Biphosphonates and denosumab for osteoporosis. Although its etiology is unclear, it may be related to a decrease in bone turnover produced by these drugs, rendering the bone more prone to generate cell necrosis during invasive dental procedures, especially in the posterior region of the jaw. There is no consensus about the prevention and treatment of this condition. The aim of this paper is to present a review of the literature with the main characteristics of osteonecrosis of the jaws associated with drugs, together with a proposal for prevention and treatment for these patients.

Interventions for preventing osteoradionecrosis of the jaws in adults receiving head and neck radiotherapy.

BACKGROUND: Osteoradionecrosis (ORN) of the jaws is among the most serious oral complications of head and neck cancer radiotherapy, arising from radiation-induced fibro-atrophic tissue injury, manifested by necrosis of osseous tissues and failure to heal, often secondary to operative interventions in the oral cavity. It is associated with considerable morbidity and has important quality of life ramifications. Since ORN is very difficult to treat effectively, preventive measures to limit the onset of this disease are needed; however, the effects of various preventive interventions has not been adequately quantified. OBJECTIVES: To assess the effects of interventions for preventing ORN of the jaws in adult patients with head and neck cancer undergoing curative or adjuvant (i.e. non-palliative) radiotherapy. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 5 November 2019), the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 10) in the Cochrane Library (searched 5 November 2019), MEDLINE Ovid (1946 to 5 November 2019), Embase Ovid (1980 to 5 November 2019), Allied and Complementary Medicine (AMED) Ovid (1985 to 5 November 2019), Scopus (1966 to 5 November 2019), Proquest Dissertations and Theses International (1861 to 5 November 2019) and Web of Science Conference Proceedings (1990 to 5 November 2019). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: We selected randomised controlled trials (RCTs) or quasi-RCTs of adult patients 18 years or older with head and neck cancer who had undergone curative or adjuvant radiotherapy to the head and neck, who had received an intervention to prevent the onset of ORN. Eligible patients were those subjected to pre- or post-irradiation dental evaluation. Management of these patients was to be with interventions independent of their cancer therapy, including but not limited to local, systemic, or behavioural interventions. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials from search results, assessed risk of bias, and extracted relevant data for inclusion in the review. Authors of included studies were contacted to request missing data. We used standard methodological procedures expected by Cochrane. MAIN RESULTS: Four studies were identified that met pre-determined eligibility criteria, evaluating a total of 342 adults. From the four studies, all assessed as at high risk of bias, three broad interventions were identified that may potentially reduce the risk of ORN development: one study showed no reduction in ORN when using platelet-rich plasma placed in the extraction sockets of prophylactically removed healthy mandibular molar teeth prior to radiotherapy (odds ratio (OR) 3.32, 95% confidence interval (CI) 0.58 to 19.09; one trial, 44 participants; very low-certainty evidence). Another study involved comparing fluoride gel and high-content fluoride toothpaste (1350 parts per million (ppm)) in prevention of post-radiation caries, and found no difference between their use as no cases of ORN were reported (one trial, 220 participants; very low-certainty evidence). The other two studies involved the use of perioperative hyperbaric oxygen (HBO) therapy and antibiotics. One study showed that treatment with HBO caused a reduction in the development of ORN in comparison to patients treated with antibiotics following dental extractions (risk ratio (RR) 0.18, 95% CI 0.43 to 0.76; one trial, 74 participants; very low-certainty evidence). Another study found no difference between combined HBO and antibiotics compared to antibiotics alone prior to dental implant placement (RR 3.00, 95% CI 0.14 to 65.16; one trial, 26 participants; very low-certainty evidence). Adverse effects of the different interventions were not reported clearly or were not important. AUTHORS' CONCLUSIONS: Given the suboptimal reporting and inadequate sample sizes of the included studies, evidence regarding the interventions evaluated by the trials included in this review is uncertain. More well-designed RCTs with larger samples are required to make conclusive statements regarding the efficacy of these interventions.

Application of Autologous Platelet-Rich Plasma on Tooth Extraction Site Prevents Occurence of Medication-Related Osteonecrosis of the Jaws in Rats.

This study evaluated the effects of local application of autologous platelet-rich plasma (PRP) on the tooth extraction site of rats presenting the main risk factors for medication-related osteonecrosis of the jaw (MRONJ). For seven weeks, senile rats were submitted to systemic treatment with vehicle (VEH and VEH-PRP) or 100 µg/Kg of zoledronate (ZOL and ZOL-PRP) every three days. After three weeks, the first lower molar was extracted. VEH-PRP and ZOL-PRP received PRP at the tooth extraction site. Euthanasia was performed at 28 days postoperatively. Clinical, histopathological, histometric and immunohistochemical analyses were carried out in histological sections from the tooth extraction site. ZOL showed lower percentage of newly formed bone tissue (NFBT), higher percentage of non-vital bone tissue (NVBT), as well as higher immunolabeling for TNFα and IL-1ß. In addition, ZOL presented lower immunolabeling for PCNA, VEGF, BMP2/4, OCN and TRAP. VEH and ZOL-PRP showed improvement in the tooth extraction site wound healing and comparable percentage of NFBT, VEGF, BMP2/4 and OCN. Local application of autologous PRP proved a viable preventive therapy, which is safe and effective to restore tissue repair capacity of the tooth extraction site and prevent the occurrence of MRONJ following tooth extraction.

Protective role of α2-macroglobulin against jaw osteoradionecrosis in a preclinical rat model.

OBJECTIVE: We have previously demonstrated the effect of alpha-2-macroglobulin (α2M) in the remediation of radiation-induced cellular damage. Here, we investigated the protective effects of α2M in a preclinical rat model of jaw osteoradionecrosis (ORN). METHODS: Eighteen rats were divided randomly into three groups: the control group, the radiation therapy (RT) alone group, and the radiated mandibles pretreated with α2M (α2M + RT) group. One month after radiation, all left molar teeth were extracted. After another 3 months, the animals were sacrificed and body weight, histopathology, microcomputed tomography and immunofluorescence were evaluated in all groups. RESULTS: The RT group showed serious alopecia, bone exposure, inflammation, necrosis, fibrosis, and the absence of new bone formation within the socket. The α2M + RT group exhibited less alopecia than the RT group and slight inflammation and fibrosis in the bone marrow cavity. The cortical bone was similar to normal bone tissue. Interestingly, compared with RT group, serum superoxide dismutase levels in the α2M + RT group increased at the 1th day (P = 0.037), 14th day (P = 0.012), while reactive oxygen species levels clearly decreased at the 1th day (P< 0.001), 14th day (P = 0.007), and 28th day (P = 0.013). CONCLUSIONS: A clinically translational model of jaw ORN was successfully established and the application of α2M prior to radiation protected the bone from being injured by the radiation, possibly related to oxidative stress.

Removal of Pre-Existing Periodontal Inflammatory Condition before Tooth Extraction Ameliorates Medication-Related Osteonecrosis of the Jaw-Like Lesion in Mice.

Medication-related osteonecrosis of the jaw (MRONJ) is a rare but detrimental intraoral lesion that predominantly occurs in patients with long-term use of antiresorptive agents, such as bisphosphonate and denosumab, a human anti-receptor activator of NF-κB ligand (RANKL) monoclonal antibody (Ab). Surgical intervention, such as tooth extraction, is a known risk factor for MRONJ, which is often performed to eliminate preexiting pathologic inflammatory conditions, such as periodontal diseases. Nonetheless, it remains unknown whether pre-existing periodontal disease condition exacerbates, or removal of such condition ameliorates, MRONJ development after tooth extraction. In this study, we combined the ligature-induced periodontitis and the tooth extraction mouse models under the administration of zoledronic acid (ZOL) or anti-RANKL Ab, and provide experimental evidence that a pre-existing pathologic inflammatory condition exacerbates MRONJ development after tooth extraction in mice. Under ZOL administration, tooth extraction alone induced ONJ lesions; however, extraction of a ligature-placed tooth further exacerbated ONJ development. When the ligature was removed and the inflammatory condition was deescalated, ONJ development was ameliorated. Anti-RANKL Ab administration resulted in similar outcomes. Interestingly, unlike ZOL-administered mice, anti-RANKL Ab-administered mice exhibited complete absence of osteoclasts, suggesting that physical presence of osteoclasts is not directly involved in ONJ development. Collectively, our study demonstrated that periodontal disease is a functionally linked risk factor that predisposes ONJ development after tooth extraction in the presence of bisphosphonate and denosumab.

Medication-related osteonecrosis of the jaw in osteoporotic patients: prevention and management.

Osteoporosis is a major, growing healthcare issue. This is especially of concern in an ageing population like that of Singapore. Osteoporotic patients are at risk of fractures, which can result in increased morbidity and mortality. The use of antiresorptive therapy with bisphosphonates or denosumab has been proven to reduce fracture risk. However, the use of these medications has rarely been associated with the development of osteonecrosis of the jaw, a potentially debilitating condition affecting one or both jaws. Appropriate understanding of the patient's antiresorptive therapy regime, as well as early institution of preventive dental measures, can play an important role in preventing medication-related osteonecrosis of the jaw (MRONJ). Regular monitoring and prompt referral to specialist care is warranted for patients with established MRONJ.

Medication-related osteonecrosis of the jaw: An update on the memorial sloan kettering cancer center experience and the role of premedication dental evaluation in prevention.

OBJECTIVE: The aim of this study was to investigate the relationship between type of antiresorptive medication and medication-related osteonecrosis of the jaw (MRONJ) onset and the role of premedication dental evaluation (PMDE) in the prevention of MRONJ. STUDY DESIGN: Our database of patients with MRONJ was reviewed. The Kruskal-Wallis test was used to analyze the onset dose of the 3 frequent medication types associated with MRONJ. To evaluate the role of PMDE in the prevention of MRONJ, all patients on antiresorptive and/or antiangiogenic medications seen in the Dental Service of Memorial Sloan Kettering Cancer Center during a 10-year period were subclassified into 2 groups. Group I comprised patients seen for PMDE before the commencement of A/A and group II patients seen after prior exposure to antiresorptive and/or antiangiogenic medications. Fischer's exact test was used to compare the incidence of MRONJ in both groups. RESULTS: Patients on denosumab developed MRONJ earlier compared with zoledronate and pamidronate (P = .003). Group I had a significantly reduced incidence of MRONJ (0.9%) compared with group II (10.5%) (P < .0001). Dentoalveolar trauma as a precipitating factor between groups I and II was not statistically significant. CONCLUSIONS: Denosumab was associated with an earlier occurrence of MRONJ compared with zoledronate and pamidronate. The role of PMDE may be an effective preventive strategy in reducing the incidence of MRONJ.

[Focus: Drug-related osteonecrosis of the jaw]. / Les médicaments inducteurs d'ostéchimionécroses des maxillaires.

Antiresorptives and antiangiogenics are treatments that have proven effective in oncology and the treatment of osteoporosis and they are increasingly prescribed. The care of these patients requires collaboration between the prescriber and the oral health professional to establish an optimized treatment plan. Therapeutic education of the patient is essential for him to understand the issues of good oral health and the adverse effects that can be caused by these treatments. The management is essentially based on the individual benefit/risk balance resulting from the general, local and inherent of the molecule risk factors. Management of drug-related osteonecrosis of the jaw should be as early as possible.

Interventions for managing medication-related osteonecrosis of the jaw.

BACKGROUND: Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse reaction experienced by some individuals to certain medicines commonly used in the treatment of cancer and osteoporosis (e.g. bisphosphonates, denosumab and antiangiogenic agents) and involves the progressive destruction of bone in the mandible or maxilla. Depending on the drug, its dosage, and the duration of exposure, the occurrence of this adverse drug reaction may be rare (e.g. following the oral administration of bisphosphonate or denosumab treatments for osteoporosis, or antiangiogenic agent-targeted cancer treatment) or common (e.g. following intravenous bisphosphonate for cancer treatment). MRONJ is associated with significant morbidity, adversely affects quality of life (QoL), and is challenging to treat. OBJECTIVES: To assess the effects of interventions versus no treatment, placebo, or an active control for the prophylaxis of MRONJ in people exposed to antiresorptive or antiangiogenic drugs.To assess the effects of non-surgical or surgical interventions (either singly or in combination) versus no treatment, placebo, or an active control for the treatment of people with manifest MRONJ. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 23 November 2016), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 10), MEDLINE Ovid (1946 to 23 November 2016), and Embase Ovid (23 May 2016 to 23 November 2016). The US National Institutes of Health Trials Registry (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on language or publication status when searching the electronic databases; however, the search of Embase was restricted to the last six months due to the Cochrane Embase Project to identify all clinical trials and add them to CENTRAL. SELECTION CRITERIA: We included randomised controlled trials (RCTs) comparing one modality of intervention with another for the prevention or treatment of MRONJ. For 'prophylaxis of MRONJ', the primary outcome of interest was the incidence of MRONJ; secondary outcomes were QoL, time-to-event, and rate of complications and side effects of the intervention. For 'treatment of established MRONJ', the primary outcome of interest was healing of MRONJ; secondary outcomes were QoL, recurrence, and rate of complications and side effects of the intervention. DATA COLLECTION AND ANALYSIS: Two review authors independently screened the search results, extracted the data, and assessed the risk of bias in the included studies. For dichotomous outcomes, we reported the risk ratio (RR) (or rate ratio) and 95% confidence intervals (CI). MAIN RESULTS: We included five RCTs (1218 participants) in the review. Three trials focused on the prophylaxis of MRONJ. Two trials investigated options for the treatment of established MRONJ. The RCTs included only participants treated with bisphosphonates and, thus, did not cover the entire spectrum of medications associated with MRONJ. Prophylaxis of MRONJOne trial compared standard care with regular dental examinations in three-month intervals and preventive treatments (including antibiotics before dental extractions and the use of techniques for wound closure that avoid exposure and contamination of bone) in men with metastatic prostate cancer treated with zoledronic acid. The intervention seemed to lower the risk of MRONJ: RR 0.10; 95% CI 0.02 to 0.39 (253 participants; low-quality evidence). Secondary outcomes were not evaluated.As dentoalveolar surgery is considered a common predisposing event for developing MRONJ, one trial investigated the effect of plasma rich in growth factors (PRGF) for preventing MRONJ in people with cancer undergoing dental extractions. There was insufficient evidence to support or refute a benefit of PRGF on MRONJ incidence when compared with standard treatment (RR 0.08, 95% CI 0.00 to 1.51; 176 participants; very low-quality evidence). Secondary outcomes were not reported. In another trial comparing wound closure by primary intention with wound closure by secondary intention after dental extractions in people treated with oral bisphosphonates (700 participants), no cases of intraoperative complications or postoperative MRONJ were observed. QoL was not investigated. Treatment of MRONJOne trial analysed hyperbaric oxygen (HBO) treatment used in addition to standard care (antiseptic rinses, antibiotics, and surgery) compared with standard care alone. HBO in addition to standard care did not significantly improve healing from MRONJ compared with standard care alone (at last follow-up: RR 1.56; 95% CI 0.77 to 3.18; 46 participants included in the analysis; very low-quality evidence). QoL data were presented qualitatively as intragroup comparisons; hence, an effect estimate of treatment on QoL was not possible. Other secondary outcomes were not reported.The other RCT found no significant difference between autofluorescence- and tetracycline fluorescence-guided sequestrectomy for the surgical treatment of MRONJ at any timepoint (at one-year follow-up: RR 1.05; 95% CI 0.86 to 1.30; 34 participants included in the analysis; very low-quality evidence). Secondary outcomes were not reported. AUTHORS' CONCLUSIONS: Prophylaxis of MRONJOne open-label RCT provided some evidence that dental examinations in three-month intervals and preventive treatments may be more effective than standard care for reducing the incidence of MRONJ in individuals taking intravenous bisphosphonates for advanced cancer. We assessed the certainty of the evidence to be low.There is insufficient evidence to either claim or refute a benefit of either of the interventions tested for prophylaxis of MRONJ (i.e. PRGF inserted into the postextraction alveolus during dental extractions, and wound closure by primary or secondary intention after dental extractions). Treatment of MRONJAvailable evidence is insufficient to either claim or refute a benefit for hyperbaric oxygen therapy as an adjunct to conventional therapy. There is also insufficient evidence to draw conclusions about autofluorescence-guided versus tetracycline fluorescence-guided bone surgery.

Preventive Effect of Phosphodiesterase Inhibitor Pentoxifylline Against Medication-Related Osteonecrosis of the Jaw: An Animal Study.

PURPOSE: The aim of this experimental study was to investigate the prophylactic effect of pentoxifylline (PTX) on medication-related osteonecrosis of the jaw (MRONJ). MATERIALS AND METHODS: Female Sprague-Dawley rats (n = 33) received zoledronic acid (ZA) for 8 weeks to create an osteonecrosis model. The left mandibular second molars were extracted and the recovery period lasted 8 weeks before sacrifice. PTX was intraperitoneally administered to prevent MRONJ. The specimens were histopathologically and histomorphometrically evaluated. RESULTS: Histomorphometrically, between the control and ZA groups, there was no statistically significant difference in total bone volume (P = .999), but there was a statistically significant difference in bone ratio in the extraction sockets (P < .001). A comparison of the bone ratio of the ZA group with the ZA/PTX group (PTX administered after extraction) showed no statistically significant difference (P = .69), but there was a statistically significant difference with the ZA/PTX/PTX group (PTX administered before and after extraction; P = .008). Histopathologically, between the control and ZA groups, there were statistically significant differences for inflammation (P = .013), vascularization (P = .022), hemorrhage (P = .025), and regeneration (P = .008). Between the ZA and ZA/PTX groups, there were no statistically significant differences for inflammation (P = .536), vascularization (P = .642), hemorrhage (P = .765), and regeneration (P = .127). Between the ZA and ZA/PTX/PTX groups, there were statistically significant differences for inflammation (P = .017), vascularization (P = .04), hemorrhage (P = .044), and regeneration (P = .04). CONCLUSION: In this experimental model of MRONJ, it might be concluded that although PTX, given after tooth extraction, improves new bone formation that positively affects bone healing, it is not prophylactic. However, PTX given before tooth extraction is prophylactic. Therefore, PTX might affect healing in a positive way by optimizing the inflammatory response.

[A PhD completed 9. The value of oral foci screening in oncology patients]. / Hora est 9. De waarde van tandheelkundig focusonderzoek bij oncologiepatiënten.

In both patients who undergo radiotherapy because of a tumour in the head and neck region and patients who are treated with high doses of chemotherapy because of haematological disorders, prior to treatment an oral foci screening is carried out. The aim of this focus investigation is to identify oral abnormalities, the so-called oral foci. Such foci can lead to oral problems during or post-treatment. A careful oral foci screening, conforming to protocol, appears to be very relevant for patients who have to undergo head and neck radiotherapy. Particular attention must be devoted to the evaluation of the perodontium, because the chance of disorders affecting the bone-healing that appear post-radiotherapy in the head and neck region is increased in patients with periodontitis. In patients with a haematological disorder, asymptomatic, chronic foci do not require treatment prior to or during the oncological treatment because such oral foci do not increase an extra risk of infectious complications, despite what was hitherto believed.

Denosumab: Prevention and management of hypocalcemia, osteonecrosis of the jaw and atypical fractures.

Denosumab, a bone-modifying agent, reduces the risk of skeletal-related events in patients with bone metastases from solid tumors and is generally well tolerated. However, hypocalcemia, osteonecrosis of the jaw (ONJ) and atypical fracture are potential and important toxicities of denosumab therapy that require attention. In pivotal phase III trials in patients with bone metastases from solid tumors, the incidence of hypocalcemia was 9.6% in denosumab-treated patients, with most events being asymptomatic, grade 2 and resolving by week 4. Established hypocalcaemia requires additional short-term calcium and vitamin D supplementation and, if severe, administration of intravenous calcium. ONJ was reported in 1.8% of patients receiving denosumab over 3 years in these trials. Involvement of an experienced oro-maxillary surgeon is important if ONJ is suspected. Atypical fractures were rare in a large study of denosumab using the dose and scheduling approved for the treatment of osteoporosis. To prevent toxicities, patients should maintain calcium and vitamin D supplementation, good oral hygiene and regular dental reviews throughout treatment. This article presents case studies from our clinical practice and discusses the pathophysiology of these toxicities along with guidance on prevention, diagnosis and management.

Bisphosphonate and Medication-Related Osteonecrosis of the Jaw: A Review.

For patients with malignant disease taking bisphosphonates and denosumab, the incidence of medication-related osteonecrosis of the jaw (MRONJ) is up to 15% in contrast to 0.01% in patients with osteoporosis. Clinical presentation of MRONJ extends from asymptomatic exposure of bone in 94% of patients to severe cases of mandibular fractures in a minority of 4.5%. The strongest risk factors for MRONJ are invasive dental procedures and dental infections. Advances in imaging provide more preoperation information compared with panoramic radiograph. Prevention strategies are the elimination of potential risk factors leading to invasive dental procedures and maintenance of good oral hygiene prior to the administration of antiresorptive agents. Management of MRONJ depends on the underlying disease, extent of the necrosis, and the presence of contributing therapy. Conservative therapies include topical anti-infective rinses and systemic antibiotic therapy. The most important part of surgical therapy is to remove the exposed and necrotic bone. Several options for defect closure are possible from local tissue flaps to microvascular free flap procedures. The development of MRONJ in conjunction with dental implants is a severe side effect and should be avoided if potentially harmful medication has already been administered.

Cause and occurrence timing of osteoradionecrosis of the jaw: a retrospective study focusing on prophylactic tooth extraction.

PURPOSE: This retrospective study aimed to analyze the relationship between tooth extraction and osteoradionecrosis (ORN) occurrence. The irradiation field, dose, and time interval between radiotherapy (RT) and ORN were reviewed. We also discuss appropriate guidelines for prophylactic tooth extraction. METHODS: A total of 33 patients treated for grade ≥2 (clinical) ORN in our department from 2002 to 2014 were enrolled. The following epidemiological data were retrospectively gathered: age, sex, histological diagnosis, primary tumor sites, radiation dose, chemotherapy, site of ORN, relationship between tooth extraction and ORN occurrence, and time interval between tooth extraction and the initiation or end of RT. RESULTS: Twenty-one percent of ORN cases resulted from tooth extraction. The most common site of ORN (82 %) was the mandibular molar region. About half of ORN cases (49 %) occurred within 2 years after RT. All patients who received tooth extraction after RT developed ORN (100 %) independently of time interval between tooth extraction and the end of RT (median interval, 37.5 months; range, 27-120 months). In contrast, only 50 % of patients who received tooth extraction before RT developed ORN. There may have been an association between the irradiation field and the site of ORN development CONCLUSIONS: ORN occurrence due to tooth extraction was 21 %. Occurrence timing of ORN did not depend on time interval between tooth extraction and the end of RT. The irradiation field is certainly related to the site of ORN; therefore, prophylactic tooth extraction should be performed in consideration of the proposed radiation field and dose.

Prevention of osteoradionecrosis of the jaws by low-intensity ultrasound in the dog model.

The prevention of osteoradionecrosis of the jaws (ORNJ) is very important because of the current absence of effective therapies for this disease. The aim of this study was to determine whether low-intensity ultrasound has a preventive effect on ORNJ. Sixty healthy adult dogs were divided randomly into three groups: group A (radiotherapy alone), group B (radiotherapy followed by low-intensity ultrasound treatment), and a control group. The development of ORNJ was assessed and the rate of occurrence of ORNJ was compared between groups A and B. Micro-computed tomography, haematoxylin-eosin staining, and immunofluorescence were used to evaluate the microstructure of the mandible and changes in microvascular density in all groups. All animals in group A and group B (ultrasound applied for 30 days) developed ORNJ. Alveolar bone density was 609.48±53.77HU in group A and 829.65±81.46HU in group B (P=0.008). The trabecular bone volume fraction, bone surface area/bone volume ratio, trabecular thickness, and trabecular number were all lower in group A than in group B (P=0.037, P=0.022, P=0.017, and P=0.034, respectively). Haematoxylin-eosin staining showed that the Haversian canals in the osteons had expanded significantly in group A, with collagen fibres losing their circular orientation; group B tended to show typical osteons. The microvascular density in group A was decreased. In conclusion, the use of low-intensity ultrasound in the dog appears not to prevent the incidence of ORNJ, however it does somewhat improve vascularity and bone quality at the microscopic level, which contribute to ORNJ healing.

Prevention of medication-related osteonecrosis of the jaws secondary to tooth extractions. A systematic review.

BACKGROUND: A study was made to identify the most effective protocol for reducing the risk of osteonecrosis of the jaws (ONJ) following tooth extraction in patients subjected to treatment with antiresorptive or antiangiogenic drugs. MATERIAL AND METHODS: A MEDLINE and SCOPUS search (January 2003 - March 2015) was made with the purpose of conducting a systematic literature review based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. All articles contributing information on tooth extractions in patients treated with oral or intravenous antiresorptive or antiangiogenic drugs were included. RESULTS: Only 13 of the 380 selected articles were finally included in the review: 11 and 5 of them offered data on patients treated with intravenous and oral bisphosphonates, respectively. No randomized controlled trials were found - all publications corresponding to case series or cohort studies. The prevalence of ONJ in the patients treated with intravenous and oral bisphosphonates was 6,9% (range 0-34.7%) and 0.47% (range 0-2.5%), respectively. The main preventive measures comprised local and systemic infection control. CONCLUSIONS: No conclusive scientific evidence is available to date on the efficacy of ONJ prevention protocols in patients treated with antiresorptive or antiangiogenic drugs subjected to tooth extraction.