Surgical Therapy for Bisphosphonate-Related Osteonecrosis of the Jaw: Six-Year Experience of a Single Institution

What Affects Healing Rates in Patients Treated for Medication-Related Osteonecrosis of the Jaw? The Role of Operative Therapy and Other Clinical Factors

BACKGROUND

In the therapy of medication-related osteonecrosis of the jaw (MRONJ), the healing rate, effectiveness of operative therapy, and factors associated with healing remain unclear.

PURPOSE

This study aimed to estimate MRONJ therapy healing rates and identify associated prognostic factors.

STUDY DESIGN, SETTING, SAMPLE

A 25-center prospective cohort study was conducted on 291 patients with MRONJ treated with a common therapeutic protocol during 2013-2016. Patients unable to continue examinations or treatment were excluded.

PREDICTOR VARIABLE

The primary predictor variable was MRONJ therapy grouped into two categories: operative and nonoperative. Secondarily, the prognostic factors categorized as demographic, medical, clinical, and perioperative were evaluated.

MAIN OUTCOME VARIABLES

The primary outcome variable was treatment duration, defined as the time (in months) between the initiation of therapy and when the site was healed or the date of the final visit or loss to follow-up.

COVARIATES

Not applicable.

ANALYSES

Descriptive statistics and 3-year cumulative healing rates were calculated. The association between clinical factors and time to healing was analyzed using bivariate and multivariate analyses and propensity score analysis. P < .05 was considered significant.

RESULTS

We analyzed data from 291 subjects with 76 (26.1%) and 215 (73.9%) subjects in the operative and nonoperative therapy groups, respectively. The healing rates for operative and nonoperative therapies were 95.8 and 70.7%, respectively (hazard ratio [HR] = 1.6, 95% confidence interval [CI] = 1.1-2.2, P value [P] < .01). The healing rates in patients for whom anti-resorptive agent (ARA) treatment was discontinued and continued were 87.2 and 37.4%, respectively (HR = 1.8, 95% CI = 1.1-3.0, P = .02). In a multiple regression analysis using ARA indication, the therapy method showed a significant association in the MRONJ malignancy group (HR = 2.75, 95% CI = 1.46-5.17, P < .01).

CONCLUSION AND RELEVANCE

Operative therapy and ARA discontinuation were associated with better healing rates in MRONJ therapy. However, the choice of therapy for MRONJ should be based on a comprehensive consideration of the patient's condition. ARA discontinuation should be considered an adjunctive measure because of the possibility of adverse events such as fragility fractures and skeletal related events.

How we manage medication-related osteonecrosis of the jaw

Bone-modifying agents (BMAs) are integral to managing patients with advanced cancer. They improve quality of survival by reducing skeletal-related events, treating hypercalcaemia and chemotherapy-induced bone loss (Coleman in Clin Cancer Res 12: 6243s-6249s, 2006), (Coleman in Ann Oncol 31: 1650-1663, 2020). Two decades ago, medication-related osteonecrosis of the jaw (MRONJ) was first reported following BMA therapy (Marx in J Oral Maxillofac Surg 61: 1115-1117, 2003). The risk of MRONJ extends over a decade following BMA treatment with bisphosphonates, complicating dental care such as extractions. In addition, MRONJ has been reported following additional therapies such as antiangiogenic agents, cytotoxic agents, immunotherapy, and targeted agents. The use of BMAs in the curative and adjuvant cancer setting is increasing, consequently the implication of MRONJ is growing. Over the past 20 years, the literature has consolidated major risk factors for MRONJ, the pathophysiology and management strategies for MRONJ. Our review aims to document the development of MRONJ preventative and management strategies in cancer patients receiving a BMA. The authors advocate the incorporation of dental oncology strategies into contemporary cancer care, to optimise long-term quality of survival after cancer treatment.

Case series of medication-related osteonecrosis of the jaw (MRONJ) patients prescribed a drug holiday

The role of a drug holiday in the management of medication-related osteonecrosis of the jaw (MRONJ) remains controversial. Current UK guidance does not recommend this practice given the lack of conclusive evidence, and potential risk of skeletal-related events or cancer metastasis. This paper aims to describe a series of fifty patients with confirmed MRONJ who were prescribed a drug holiday as part of their management. Data were collected on exposures including: anti-resorptive and/or anti-angiogenic drug history, duration of drug, method of administration, concurrent therapy, MRONJ stage, management of MRONJ and duration of drug holiday. The primary outcome was complete healing as documented in the clinical notes. Multivariate Cox regression analysis was performed to evaluate the association between exposures and primary MRONJ outcome. Models were adjusted for age, sex, and index of multiple deprivation. Survival analysis was performed using a log-rank test, censoring any patients with no primary outcome recorded (p < 0.05). A total of 44% of patients stopped their medication for >36 months. Over half of all MRONJ cases presented in the posterior mandible and dental extraction was the most common precipitating factor (76%). Almost three-quarters (72%) of patients achieved complete healing. MRONJ recurrence (new site) was reported at 30%, mainly in those with incomplete healing of the initial area. There was a lack of evidence for an association between all recorded exposures and the primary MRONJ outcome using multivariate Cox regression. Similarly, we did not demonstrate evidence for an association between the duration of the drug holiday and MRONJ outcome. Our results support published guidelines, which do not recommend the discontinuation of bone modifying drugs for the prevention of MRONJ, or as part of treatment for established MRONJ.

Medication-Related Osteonecrosis of the Jaw—A Continuing Issue

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is a condition that is becoming more common in the everyday practice of both dental and maxillofacial surgeons. Materials and methods: This paper aims to provide a comprehensive and easy to read by clinicians presentation of comprehensive, accessible, and up-to-date data on MRONJ. The individual chapters focus on the etiology, epidemiology, diagnosis, prevention, treatment, and recurrence of MRONJ. Results and discussion: It has been observed over the years that among drugs that increase the risk of the disease, apart from bisphosphonates, angiogenesis inhibitors and anti-RANKL monoclonal antibodies should also be included. A thorough physical and subjective examination, periodic correction of dental prostheses, and an adequate preparation for even the simplest of procedures in the oral cavity area can prevent or minimize the risk of MRONJ. Conclusions: It is extremely difficult to treat once it occurs and oftentimes is a recurring problem that leads to a multitude of symptoms that gradually decrease the quality of a patient’s life.

The Treatment of Medication-Related Osteonecrosis of the Jaw (MRONJ): A Systematic Review with a Pooled Analysis of Only Surgery versus Combined Protocols

Medication-related osteonecrosis of the jaw (MRONJ) is a serious adverse reaction of antiresorptive and antiangiogenic agents, and it is also a potentially painful and debilitating condition. To date, no specific studies have prospectively evaluated the efficacy of its treatment and no robust standard of care has been established. Therefore, a systematic review (2007–2020) with a pooled analysis was performed in order to compare MRONJ surgical techniques (conservative or aggressive) versus combined surgical procedures (surgery plus a non-invasive procedure), where 1137 patients were included in the pooled analysis. A statistically significant difference in the 6-month improvement rate, comparing combined conservative surgery versus only aggressive (91% versus 72%, p = 0.05), was observed. No significant difference regarding any group with respect to the 6-month total resolution rate (82% versus 72%) was demonstrated. Of note, conservative surgery combined with various, adjuvant, non-invasive procedures (ozone, LLLT or blood component + Nd:YAG) was found to achieve partial or full healing in all stages, with improved results and the amelioration of many variables. In conclusion, specific adjuvant treatments associated with minimally conservative surgery can be considered effective and safe in the treatment of MRONJ, although well-controlled studies are a requisite in arriving at definitive statements

Cilostazol and Tocopherol in the Management of Medication-Related Osteonecrosis of the Jaw: New Insights From a Case Report

Several treatment protocols for medication-related osteonecrosis of the jaw (MRONJ) have been published. Despite the efficacy of surgical therapy of approximately 90% as primary therapy, the role of other agents, such as drug administration, should not be underestimated. Based on previous experience with osteoradionecrosis, the association of pentoxifylline and tocopherol has shown encouraging results in MRONJ patients. Despite the need for long-term use of the combination, compliance has been good. However, studies in breast cancer patients revealed that pentoxifylline can require dose reduction or discontinuation due to nausea and epigastric pain. Cilostazol has been used as a substitute for pentoxifylline in peripheral artery disease. Herein we report a case in which cilostazol replaced pentoxifylline at a dose of 100mg, 2 times/day with tocopherol 500UI, 2 times/day, in a 77-year-old female patient that could not tolerate pentoxifylline for the management of MRONJ. After an uneventful 22 months of follow-up, a cone-beam computed tomography revealed complete bone formation and no signs of recurrence. Cilostazol may be a useful and safe alternative to pentoxifylline as part of MRONJ management protocols.

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

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

Human amniotic membrane: an improvement in the treatment of Medication-related osteonecrosis of the jaw (MRONJ)? A case-control study

The aim of this article is to report the results obtained by the use of HAM in surgical wound healing and the reduction of relapse in patients affected by Medication-related osteonecrosis of the jaw (MRONJ).The study involved patients with the diagnosis of MRONJ, surgically treated between October 2016 and April 2019, in a case-control setting. Enrolled patients were randomly divided into 2 groups. One group will be treated with resective surgery and with the insertion of HAM patch (Group A), while the second group had been treated exclusively with resective surgery (Group B).The patients underwent MRONJ surgical treatment with the placement of amniotic membrane patches at the wound site. Data regarding the long-term complications/functions were evaluated at 3, 6, 12, and 24 months after surgery. Pain measurements were performed before the intervention (T0), 7(T1) and 30(T2) days after surgery. 49 patients were included in the study. 2 patients of GROUP A after 30 days since they were surgically treated showed persistent bone exposure. 5 patients of group B demonstrated a lack of healing of the surgical wound with the persistence of bone exposed to 30 days after surgery. Statistical analysis ruled out any difference in OUTCOME (relapse) between GROUP A and B (p = 0.23). However, the Fisher test highlighted a significant difference between the use of HAM and only surgical treatment in pain at rest (p = 0.032). The use of amniotic membrane implement the patient's quality of life and reduce pain perception. has a learning curve that is fast enough to justify its routine use.

A systematic review of metastatic cancer presenting in osteonecrosis of the jaws (MC-ONJ) in patients undergoing antiresorptive and/or antiangiogenic therapy for skeletal-related adverse events

INTRODUCTION

Osteonecrosis of the jaw (ONJ) is reported to be primarily associated with patients receiving bisphosphonate therapies but has been found in patients taking a number of other medications. A number of recent reports have noted the presence of metastatic cancers in the histologic analysis of osteonecrotic lesions from the jaw. The aim of the present review is to estimate the frequency and the type of metastatic cancer most commonly found in ONJ specimens in patients undergoing antiresorptive and/or antiangiogenic drug therapy.

MATERIAL AND METHODS

A multidatabase (PubMed, MEDLINE, EMBASE, and CINAHL) systematic search was performed. Any studies involving human participants treated with antiresorptive and antiangiogenic drugs were considered. Where study patients presented with malignant cells within osteonecrotic specimens, further data were collected. Data are presented using descriptive statistics.

RESULTS

A total of 13 studies met the inclusion criteria for this systematic review. Thirty-seven study patients had histologic evidence of malignant cells within medication-related osteonecrosis of the jaw (MRONJ) specimens. The most frequent phenotype of malignant cells found within MRONJ specimens were breast cancer variants (n = 15). The frequency of malignant tumor cells found within the MRONJ specimens was calculated using 4 studies. Out of 604 patients, the frequency was 4.64% (n = 28).

CONCLUSIONS

Based on the limited data available in the literature, it is plausible that not histologically analyzing all ONJ specimens could result in a small number of undiagnosed and untreated malignant diseases. Additional data based on a larger cohort of study patients is necessary to understand the role of MRONJ in metastatic spread and the influence of surgical treatment and reoccurrence.

The effect of concentrated growth factor (CGF) in the surgical treatment of medication-related osteonecrosis of the jaw (MRONJ) in osteoporosis patients: a randomized controlled study

OBJECTIVES

The purpose of this present study was to evaluate the efficiency of the growth factors delivered by concentrated growth factor (CGF) on the healing process of osteoporotic patients with medication-related osteonecrosis of the jaws (MRONJ).

METHODS

This randomized controlled study was composed of osteoporotic female patients who were treated with oral bisphosphonates (BPs) and diagnosed with MRONJ. For the CGF group, each patient was treated with a local application of CGF at the surgical site after removing the necrotic bone, while the surgical area was primarily closed as traditional surgical therapy for the control group. The patients underwent clinical examinations for 6 months postoperatively to check the presence of infection and dehiscence.

RESULTS

Complete healing was achieved in 19 patients of 28 patients (mean age: CGF group, 73.57 ± 5.1; control group, 73.64 ± 5.49) diagnosed with MRONJ. There was no significant difference in post-op healing data between groups during healing periods (p > 0.05). In the CGF group (n = 14) in three cases, bone exposure without infection was detected, and one of them showed a recurrent infection. In the control group (n = 14) in six cases, bone exposure without infection was detected, and three of them also showed recurrent infection.

CONCLUSION

Although our results were not statistically significant, our findings suggest that the local application of CGF appears to be an effective approach to the surgical treatment of MRONJ in osteoporosis patients by improving tissue regeneration.

CLINICAL RELEVANCE

A specific treatment protocol to manage MRONJ is still controversial. This study justifies that CGF can be used in combination with surgical treatment.

Surgical strategy for medication-related osteonecrosis of the jaw (MRONJ) on maxilla: A multicenter retrospective study

Background/purpose

Because the anatomy and the nature of the bone tissue between the mandible and maxilla are largely different, more site-specific studies are required to improve the healing rate on medication-related osteonecrosis of the jaw (MRONJ). The present study assessed maxillary MRONJ that was treated by surgery to understand its clinical characteristics, and to identify critical factors that influenced outcomes.

Materials and methods

The medical records of 54 patients with maxillary MRONJ who underwent surgery were retrospectively reviewed. Variables related to the prognosis of MRONJ were extracted from the medical records and imaging, and were statistically analyzed. We also evaluated the concomitant maxillary sinusitis (MS) after the surgical treatment of MRONJ, based on CT evaluation and change of symptoms.

Results

The healing rate of surgery for maxillary MRONJ was 85.2%, which suggested that surgical treatment is an effective strategy for treating maxillary MRONJ. Multivariate analysis revealed that postoperative residual necrotic bone was a poor prognosticator for maxillary MRONJ. Among 10 patients who did not obtain healing of MS postoperatively, 8 patients showed an improvement.

Conclusion

Our results indicate that surgical treatment is an appropriate strategy for maxillary MRONJ and complete resection of necrotic bone (i.e., extensive surgery) is needed to obtain complete healing of maxillary MRONJ. Concomitant MS tends to be healed or improved clinically in combination with the healing of maxillary MRONJ.

Management of Medication-Related Osteonecrosis of the Jaw (MRONJ) Using Leukocyte- and Platelet-Rich Fibrin (L-PRF) and Photobiomodulation: A Retrospective Study

Background. The aim of this study was to compare retrospectively the effect of three different treatment protocols on the healing outcome in patients with established medication-related osteonecrosis of the jaw (MRONJ). Methods. A total of 34 MRONJ patients were recruited from the Department database and were divided according to the treatment protocols in a study group (G1) and two control groups (G2 and G3). G1 was treated with antibiotic therapy, surgery, leukocyte- and platelet-rich fibrin (L-PRF), and photobiomodulation; G2 was treated with antibiotic therapy and surgery; G3 was treated with antibiotic therapy and photobiomodulation. Various clinical variables and treatment protocols were analyzed to determine their correlation with the healing outcome at three and six months of follow-up. Results. There was a significant association between the different treatment protocols and the outcomes at both three and six months follow-up (p = 0.001 and p = 0.002, respectively). No significant association was observed between the outcomes and MRONJ localization, MRONJ stage, duration of drug treatment, gender, diabetes, corticosteroid therapy, smoking habits, underlying disease, and history of chemotherapy at both three and six months follow-up. Conclusions. Our results show that the combination of antibiotic therapy, surgery, L-PRF, and photobiomodulation may effectively contribute to MRONJ management.

Clinical profile of individuals with bisphosphonate-related osteonecrosis of the jaw: an integrative review

BACKGROUND

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is still the most prevalent type of osteonecrosis with clinical relevance. In Brazil, bisphosphonate use is high but there is a lack of epidemiological studies on BRONJ.

OBJECTIVE

To determine the clinical profile of BRONJ in a Brazilian population through an integrative review.

DESIGN AND SETTING

Integrative review of BRONJ in a Brazilian population.

METHODS

Cases and clinical research on Brazilians with BRONJ between 2010 and 2019, indexed in PubMed/MEDLINE, Scopus, Web of Science and LILACS were reviewed. Age, sex, type and time of bisphosphonate intake, administration route, related diseases, region of the BRONJ, diagnostic criteria, staging, triggering factor and type of treatment were analyzed.

RESULTS

Fifteen articles on 128 subjects were included. Most patients were women (82.03%); the mean age was 63 years. Intravenous zoledronic acid was mostly used (62.50%), for breast cancer treatment (46.87%). The main localization of BRONJ was the mandible (54.68%), associated mainly with tooth extractions (45.98%). The diagnostic criteria were clinical (100%) and radiographic (89.06%), mostly in stage II (68.08%). The surgical treatments were sequestrectomy (37.50%) and platelet-rich plasma (PRP) (36.71%). Microbial control was done using chlorhexidine (93.75%) and infection control using clindamycin (53.90%).

CONCLUSIONS

BRONJ had higher prevalence in Brazilian women receiving treatment for breast cancer and osteoporosis. The mandible was the region most affected with a moderate stage of BRONJ, particularly when there were histories of tooth extraction and peri-implant surgery. Sequestrectomy with additional drugs and surgical therapy was the treatment most accomplished.

Efficacy of a high-dose antiresorptive drug holiday to reduce the risk of medication-related osteonecrosis of the jaw (MRONJ): A systematic review

A temporary discontinuation (drug holiday) of high-dose antiresorptive (AR) agents has been proposed to reduce the risk of medication-related osteonecrosis of the jaw (MRONJ). The aim of this systematic review was to answer the question: Is high-dose AR drug holiday, at the time of tooth extraction or dentoalveolar surgery, necessary to prevent the development of MRONJ in patients with cancer? This protocol was registered in the PROSPERO database. Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant studies up to and including April 2019. Randomized controlled trials (RCTs), cohort and cross-sectional studies, surveys, and case reports with more than five patients were included. Records were imported into www.covidence.org. Electronic searches were supplemented by manual searches and reference linkage. The Preferred Reporting Items for Systematic Reviews and Meta Analysis (PRISMA) were followed. Although only one study fitted the population, intervention, comparison, outcome (PICO) framework, valuable information on AR drug holiday could be extracted from 14 of 371 reviewed articles. Among these, 3 were prospective and 11 were retrospective studies. These studies described or evaluated high-dose AR drug holidays. In 2 studies, patients were being treated with denosumab, but neither showed that a drug holiday was effective. The remaining 12 studies evaluated bisphosphonate treatment and 2 of these studies found no reason to use AR drug holiday before surgery. Three studies recommended drug holidays, whereas most of the studies recommended assessing each patient separately. The only paper that fitted the PICO approach was a non-randomized, prospective study with a control group. This study concluded that drug holiday was not necessary. Thus, there are no evidence for using drug holiday, but it is also clear that caused by a limited numbers of eligible patients, and a great variation in between these patient, high-level evidence for using AR drug holiday is almost impossible to obtain.

Evaluation of the bactericidal effect of cold atmospheric pressure plasma on contaminated human bone: an in vitro study

The use of cold atmospheric pressure plasma (CAPP) as a bacterial decontaminant for chronic wounds has shown good results. The purpose of this in vitro study was to evaluate the bactericidal effects of CAPP on the cancellous area of the bone. Sterile glass slides and processed sterile human bone allografts 1, 2, 3, and 4mm thick were used for initial contamination and further CAPP treatment. Each block was contaminated with Staphylococcus aureus suspension on one side. Each slide was turned 180° and treated on the reverse side. The bacterial count in colony-forming units (CFU) was then measured and compared with that of a control group, and the bactericidal effects of CAPP in relation to bone density evaluated. A significant reduction in count was measured between treated and untreated groups (groups A-D: p<0.01 and group E: p=0.04). A strong positive linear relation was found between bone density and the S aureus count (r=0.844, p=0.156). Treatment with CAPP had a bactericidal effect on bone structures with a penetration depth of up to 4mm. It might be used for all diseases involving infected bone, and so extends the existing range of treatments.

Strontium ion reinforced bioceramic scaffold for load bearing bone regeneration

Bone defects in load bearing areas require bone reconstruction with strong biomaterial having mechanical characteristics like cortical bone. Bioceramics are biomaterials that support bone formation as well as provide adequate mechanical properties. A strontium substitution of the bioceramic is expected to further increase its bioactivity by enhancing osteogenesis and protect the bone from osteoclastic resorption. The study involves development, characterization and in vivo testing of a newly developed strontium substituted hydroxyapatite based bioceramic scaffold (SrHAB) with sufficient biomechanical properties. Optimal concentration of strontium ion required for enhanced osteogenic differentiation was identified by comparing three compositions of SrHAB scaffold; namely Sr10HAB, Sr30HAB and Sr50 HAB for their Alkaline phosphatase activity in vitro. The selected Sr10HAB scaffold demonstrated in vivo bone formation with osteogenic differentiation of stromal derived mesenchymal stem cells (MSC) from human and ovine sources in ectopic and ovine models. Thus, Sr10HAB scaffold has a potential for application in load bearing bone requirements of orthopaedics and dentistry.

Refractory healing after surgical therapy of osteonecrosis of the jaw: associated risk factors in aged patients

Purpose: Osteonecrosis of the jaw (ONJ), both medication-related and non medication-related, mainly occurs in aged patients. It needs surgical intervention. Refractory healing after an operation of ONJ can significantly lower the quality of life of elderly patients. The purpose of this study was to determine risk factors associated with refractory healing in aged patients.

Patients and methods: We performed a retrospective study of ONJ in aged patients who underwent surgical treatments in a single institute during a 12-year period. Multiple logistic regression analysis was used to determine independent risk factors associated with refractory healing.

Results: A total of 122 patients were included. Of them, 25 patients were identified as the refractory group and 97 patients as the control group. Diabetes mellitus (DM) (AOR=5.03, 95% CI: 1.74–14.52) and glucocorticoid administration (AOR=7.97, 95% CI: 2.52–25.23) were found to be significant risk factors for refractory healing of ONJ.

Conclusion: DM and medication of glucocorticoid might be risk factors for refractory healing of ONJ.

Treatment outcomes and prognostic factors of medication-related osteonecrosis of the jaw: a case- and literature-based review

OBJECTIVES

The purpose of this study was to investigate the treatment outcomes and prognostic factors of medication-related osteonecrosis of the jaw (MRONJ) in Japanese patients.

PATIENTS AND METHODS

Among 409 cases, treatment outcomes and prognostic factors were investigated in 275 patients. In statistical analyses, the 1-year cumulative curative rate was calculated with the Kaplan-Meier method, and significance was examined with the Wilcoxon test. Cox's proportional hazards regression analysis was used for the multivariate analysis.

RESULTS

Resolution of the disease was achieved in 137 out of 275 MRONJ patients (49.8%). One-year cumulative curative rates were 39.8% in stage 1 patients, 26.3% in stage 2, and 19.0% in stage 3. The 1-year cumulative curative rates of treatment interventions were 17.2% for conservative treatment, 34.5% for sequestrectomy, and 40.7% for extended surgery including bone resection and segmental resection. As the prognostic factors of treatment outcomes, the type of medication, stage of MRONJ, and type of surgical intervention were identified as independent factors in a multivariate analysis.

CONCLUSION

These results suggest that surgical interventions may lead to a good prognosis in MRONJ patients.

CLINICAL RELEVANCE

This study indicated that surgical intervention for MRONJ might lead to improvement of prognosis and quality of life in MRONJ patients.

A literature review of perioperative antibiotic administration in surgery for medication-related osteonecrosis of the jaw

PURPOSE

Few studies exist that focus on the details of perioperative antibiotic administration for surgery to treat medication-related osteonecrosis of the jaw (MRONJ). The regime and duration of perioperative antibiotics applied in published studies were reviewed to clarify appropriate perioperative antibiotic use in MRONJ surgery.

METHODS

A literature search was conducted using the MEDLINE database via PubMed.

RESULTS

The search resulted in 453 hits on PubMed. After reading the downloaded full-text articles, 17 articles met the inclusion and exclusion criteria. The most common perioperative antibiotic used for MRONJ surgery was a combination of penicillin-based antibiotics and β-lactamase inhibitor (52.9%), and the second most common regime was penicillin-based antibiotics with metronidazole (17.6%). The duration of administration was 2 weeks postoperatively in nine studies, whereas four studies applied long-term administration (2-6 weeks postoperatively).

CONCLUSIONS

Oral and maxillofacial surgeons mostly prefer penicillin-based antibiotics plus β-lactamase inhibitor or metronidazole for MRONJ surgery. The duration of administration of these medications may be based on empirical experience.

Microbial diversity in infections of patients with medication-related osteonecrosis of the jaw

OBJECTIVES

A central role of infections in the treatment of MRONJ patients is widely accepted. An investigation of the MRONJ lesions' biofilms as potential pathogens seems logical.

MATERIALS AND METHODS

We investigated the clinical data of our MRONJ patients who received surgery in advanced stage of the disease. Special attention was granted to the local colonizers harvested from osseous MRONJ specimens and submucosal putrid infections.

RESULTS

Eleven out of 71 patients presented a spontaneous onset of the disease and for 60 out of 71 patients a trigger was detected. Breast cancer (29.6%) and prostate cancer (22.5%) were the most frequent underlying disease for prescription of an antiresorptive therapy, mostly zoledronate. Submucosal soft tissue biofilms significantly differed from biofilms harvested from the MRONJ lesions bottom, yet the most frequent bacteria were equally present in both groups: Streptococcus species (spp.), Prevotella spp., Actinomyces spp., Veillonella spp., and Parvimonas micra. The cephalosporins, cefuroxime and cefotaxime, and ß-lactam antibiotics with ß-lactamase inhibitor revealed the greatest susceptibility for the detected bacteria.

CONCLUSION

The bacteria from the submucosal areas and the bottom of the infected bone presented comparable susceptibility to the common antibiotics regimes. Streptococcus spp., Prevotella spp., and Veillonella spp. present a high abundance in MRONJ lesions beside Actinomyces spp. The MRONJ lesions bottom is in many cases not infected by Actinomyces spp.

CLINICAL RELEVANCE

The removal of the necrotic bone reduces the variety of bacteria found in MRONJ lesions, in particular at the bottom of the lesion.

Clinical characteristics and recurrence-related factors of medication-related osteonecrosis of the jaw

OBJECTIVES

The purpose of this study was to investigate the demographic and clinical characteristics of patients with medication-related osteonecrosis of the jaw (MRONJ) and to elucidate factors affecting recurrence in surgical treatment.

MATERIALS AND METHODS

A total of 51 patients who were diagnosed with MRONJ were analyzed according to demographic and clinical features and treatment results through a retrospective chart review from 2013 to 2017 in the Department of Oral and Maxillofacial Surgery, Korea University Anam Hospital, Seoul in Korea.

RESULTS

Alendronate composed the majority of medication doses (55.6%), followed by ibandronate (20.0%), risedronate (15.6%), and zoledronate (6.7%). Forty patients (88.9%) were given oral medication, and five patients (11.1%) were intravenously treated, and the mean duration of medication use was 61.1±42.9 months. A total of 10 patients (22.2%) had a drug holiday before MRONJ-induced dental treatment lasting an average of 6.8±7.0 months. MRONJ occurred 2.7 times more in the mandible, with 41 cases (73.2%) occurring in the mandible and 15 cases (26.8%) occurring in the maxilla, and the prevalence of affected posterior parts (premolar-molar) was six times greater than that of the anterior parts (incisor-canine) (48 cases vs 8 cases, 85.7% vs 14.3%). The most common dental cause of MRONJ was tooth extraction (69.6%). Regarding recurrence, there was no statistical difference in recurrence rate according to either site or stage. However, recurrence occurred in 4 out of 34 cases (11.8%) in the primary closure group and 9 out of 20 cases (45.0%) in the secondary healing group, and there was a statistical difference with respect to closure technique.

CONCLUSION

The identified risk factors in patients taking bone resorption inhibitors can aid dental clinicians in ensuring prevention and proper treatment of MRONJ.

Total mandibulectomy defect in the setting of chronic bisphosphonate use

Bisphosphonates are among several drugs known in modern medicine to have a potentially deleterious effect on the mandible with chronic use. While purportedly causing a necrotic reaction in the bone, the complete mechanism is not fully elucidated yet as cases are quite rare in the general public. Despite the esoteric nature of this entity, patients suffering from bisphosphonate induced necrosis have a complicated and prolonged course often involving varying degrees of mandibular debridement with severe cases requiring reconstruction. In this report, we present the unique case of a patient with a progressive mandibular osteonecrosis requiring complete mandibulectomy and fibula flap reconstruction.

Medication-related osteonecrosis of the jaw: Prevention, diagnosis and management in patients with cancer and bone metastases

Medication-related osteonecrosis of the jaw (MRONJ) is primarily an adverse side effect of denosumab or bisphosphonates (particularly when used at high doses to prevent skeletal-related events [SREs] in patients with cancer and bone metastases) or possibly anti-angiogenic cancer treatment. While the implementation of preventive measures over recent years has reduced the risk of MRONJ in patients with bone metastases due to cancer, it is imperative to balance the risk of MRONJ against the beneficial effects of treatment with denosumab or bisphosphonates on the skeletal health of patients. Despite growing awareness of MRONJ within the medical community, there is a lack of large-scale, prospective clinical studies in this rapidly evolving field. Discussing preventive measures with patients and implementing them, both before and during treatment with bisphosphonates or denosumab, is the best option to reduce the risk of MRONJ. In particular, avoiding bone trauma and preventing and treating dental infections before and during denosumab or bisphosphonate therapy is crucial to minimize the risk of MRONJ. If MRONJ develops, conservative (non-surgical) treatment can provide symptom relief, but achieving mucosal closure remains challenging. When management of symptoms and mucosal healing are the ultimate goals of therapy, or after failure of conservative treatment, a surgical approach may be beneficial. This critical review, based on a best-evidence review of currently available literature, provides clear practical guidelines to help to prevent, manage and treat MRONJ. Overall, a multidisciplinary, pragmatic approach to MRONJ should be adopted, prioritizing patient's quality of life and management of their skeletal malignant disease.

Antiresorptive drug-related osteonecrosis of the jaws, literature review and 5 years of experience

PURPOSE

Bisphosphonate drug therapy provides benefits in the case of osteoporosis and carcinomas metastasizing to the bones, but it exposes patients to important side effects. The aim of this study was to investigate the incidence and the appropriate surgical treatment of bone lesions and fractures due to antiresorptive drug-related osteonecrosis of the jaws (ARONJ).

METHODS

Patients presenting with osteonecrosis lesions of the jaw, who were referred to the Maxillo-Facial unit of the University of L'Aquila, were considered for inclusion. Grade of the lesion and treatment choice was recorded for each patient. Descriptive statistics were calculated and the data were analysed with Chi-squared tests. A representative case of a fracture reduction with a supra-periostal approach is reported.

RESULTS

Among the 165 patients with ARONJ lesions, 112 were female and 53 were male. In total, 115 patients received intra-venous bisphosphonate therapy and 50 received oral bisphosphonate therapy. Five stage 2 lesions, three stage 2 lesions and two stage 3 lesions were not a consequence of dental procedures. Eighteen surgical bone excisions were performed and four pathological fractures were reduced. In one case (the reported one), the combined use of platelet-rich plasma and the supra-periostal approach leads to a successful 1-year follow-up.

CONCLUSIONS

ARONJ lesions are a type of pathological bone disease affecting the jawbones. The pathology pathway remains a controversial and frequently discussed topic. A surgically conservative strategy seems to be the best way to assure a comfortable quality of life to those patients negatively affected by this condition.

Comparison of mucosal and mucoperiosteal wound cover for the treatment of medication-related osteonecrosis of the jaw lesions: a retrospective cohort study

OBJECTIVES

Actually, there is no detailed guidance on how to deal with wound closure after surgical removal of medication-related osteonecrosis of the jaw (MRONJ) lesions. This study attempts to compare the difference in outcome between the mucosal and the mucoperiosteal flap closure after surgery.

PATIENTS AND METHODS

In this retrospective monocentric cohort study, patients (n = 61; 35 female/26 male) suffering from MRONJ and requiring surgical therapy at the University of Aachen between 2013 and 2015 were included. Due to intra-institutional variances, one group was treated with the mucosal, the other group with the mucoperiosteal technique. The success rate, i.e., mucosal closure and no relapse at the point of follow-up, was evaluated and compared. All patients were clinically investigated for the postoperative follow-up during a special consultation appointment.

RESULTS

The success rates between the different techniques after 2 years follow-up were very similar. In the group of mucosal wound closure, 22 of 29 (75.86%) patients revealed mucosal integrity without signs of MRONJ. The rate in the mucoperiosteal wound closure group was almost identical (24 of 32 (75%)).

CONCLUSION

No differences in the success rates between the two different techniques could be evaluated.

CLINICAL RELEVANCE

The results of this study suggest that the complete removal of the necrotic bone might have a higher impact on the success rates than the technique of the wound closure. Due to the fact that the mucoperiosteal wound closure technique offers a better overview of the extent of the MRONJ lesion, the authors advise to use this technique.

Stage-specific therapeutic strategies of medication-related osteonecrosis of the jaws: a systematic review and meta-analysis of the drug suspension protocol

OBJECTIVE

The most debated topic about medication-related osteonecrosis of the jaws (MRONJ) is its therapy, as there are no definitive guidelines. The aims of this systematic review were (a) to outline the best therapeutic approach according to the stage at diagnosis and (b) to perform a meta-analysis to assess whether the drug-holiday protocol may be or not an effective method in the management of MRONJ patients.

MATERIALS AND METHODS

The systematic review was performed following the PRISMA principles. Results were screened according to inclusion and exclusion criteria regarding staging before/after treatment, follow-up, and information provided by the authors. For statistical analysis, linear variables are reported as means and standard deviations, medians, and inter-quartile range (IQR); normality of data, according to the distribution of complete healing (primary outcome variable), was assessed with the Kolmogorov-Smirnov test. A p value < 0.05 was considered statistically significant for all tests.

RESULTS

Thirteen studies were selected out of 1480. None of them was case-controlled or randomized. Conservative approach showed good results at early stages, but heterogeneous result at advanced stages (100% stage 0, stage I range 81-97%, stage II range 63.6-100%, stage III 73%). Surgical approach showed heterogeneous results at all stages (stage I range 0-100%, stage II range 52-100%, stage III range 50-100%). Statistical analysis showed a significantly higher prevalence of completely healed sites in patients who followed the drug-holiday protocol.

CONCLUSIONS

The results suggest that the current stage-specific approach for MRONJ therapy is based on a sound clinical rationale. Conservative treatment appears to yield better outcomes at early stages, while further investigations are needed to elucidate the best protocols for the management of advanced stages. The drug-holiday protocol statistically promotes complete healing after oral surgery procedures but the application should be dictated by the condition of each patient.

CLINICAL RELEVANCE

At present, early MRONJ stages should be primarily treated by means of a conservative approach while more advanced stages must be carefully evaluated. Individual decisions should be made for every single case even with respect to the drug-holiday protocol.

Nasolabial Flap Improves Healing in Medication-Related Osteonecrosis of the Jaw

PURPOSE

Medication-related osteonecrosis of the jaw (MRONJ) is an adverse side effect of antiresorptive and antiangiogenic therapeutic agents that is difficult to treat owing to its high relapse rate. The aim of the present study was to determine whether patients with MRONJ treated using decortication and a nasolabial flap compared with those who underwent decortication with mucoperiosteal flaps have better outcomes regarding stable wound closure.

MATERIALS AND METHODS

Two groups of patients with MRONJ and intraoral exposed bone were evaluated in a cohort clinical study retrospectively. The primary predictor variable was the treatment group. The experimental group used the nasolabial flap for wound closure, and the control group used the mucoperiosteal flap for closure. The outcome variable was successful wound closure defined as a symptomless and closed wound after at least 12 months. Other study variables included factors such as perioperative drug holiday, duration of postoperative oral antibiotic administration, and postoperative use of nasogastric feeding tubes. Cox proportional hazard regression analysis and Kaplan-Meier curves were used to determine the factors independently associated with the dependent variable. The Mann-Whitney U test and χ² test were used for analyses regarding group-related data.

RESULTS

Both groups showed similar demographics. The 16 study patients receiving nasolabial flaps had a mean age of 69.9 years, and the 16 control patients receiving mucoperiosteal flaps had a mean age of 71.8 years. Both groups included 10 women and 6 men. Of the 16 patients in each group, 15 had received a bisphosphonate and 1, monoclonal antibody therapy. All evaluated patients underwent combined treatment, including decortication and intravenous antibiotics. Of the 16 patients receiving nasolabial flaps, symptomless intact wound closure was achieved in 68.8%. Of the 16 patients with mucoperiosteal closure, 18.7% achieved wound closure, with 81.2% developing a relapse of MRONJ, a statistically significant difference (P < .001). No statistically significant differences were found between the 2 groups in the demographic variables. The mean interval to relapse for the experimental and control groups was 13.6 ± 7.8 and 8.2 ± 7.9 months, respectively (P = .017).

CONCLUSIONS

MRONJ is a complication of antiosteoclastic treatment of mostly oncologic, palliative patients, which requires a very methodical approach to surgical treatment. A variety of different methods have been reported. The use of nasolabial flaps can be considered as a highly reliable option for coverage the bone wound with less morbidity than microvascular free flaps and better long-term results compared with mucoperiosteal flaps.

Surgical treatment of stage 2 medication-related osteonecrosis of the jaw compared to osteomyelitis

OBJECTIVE

To compare the characteristics and outcomes of patients who underwent surgical treatment for stage 2 medication-related osteonecrosis of the jaw (MRONJ) versus osteomyelitis.

METHODS

This retrospective study compared the following variables in 73 patients with stage 2 MRONJ versus 89 patients with osteomyelitis: impaired wound healing after surgery, sex, age, the presence of actinomycosis, location of the jaw lesion, and involvement of the inferior alveolar nerve (IAN).

RESULTS

There were significant differences between the groups in age, sex, rates of impaired wound healing, actinomycosis, and the location (anterior/posterior) of the lesion. Impaired wound healing after surgical treatment in the stage 2 MRONJ group was associated with patient age. All patients with impaired wound healing after the initial surgery recovered fully after reoperation.

CONCLUSIONS

These findings for surgical treatment of stage 2 MRONJ may help clinicians plan surgical treatment of MRONJ.

Use of Leukocyte- and Platelet-Rich Fibrin in the Treatment of Medication-Related Osteonecrosis of the Jaws

Lesions associated with medication-related osteonecrosis of the jaws (MRONJ) are refractory to different treatment approaches. Hence, auxiliary approaches capable of improving patient outcomes should be explored. Leukocyte- and platelet-rich fibrin (LPRF) is a second-generation platelet concentrate (natural autologous fibrin matrix). It shows anti-infectious activity through immune regulation and accelerates the angiogenesis and multiplication of fibroblasts and osteoblasts; in consequence, it stimulates soft tissue healing and prevents exposure of the alveolar bone in the oral cavity. This report describes 2 cases involving women with breast cancer who were being treated with zoledronic acid and exhibited advanced MRONJ. In case 1, MRONJ developed in the maxilla after dental extraction; in case 2, it was assumed that MRONJ arose spontaneously in the mandible because no other risk factors could be detected. These cases were managed with surgical resection of the necrotic bone followed by placement of an LPRF membrane. Complete wound healing and intact mucosal cover were achieved. At clinical and tomographic follow-up after 2 years, there were no oral lesions or complaints. Therefore, this could be a noninvasive, quick, and alternative approach to manage bone exposure. The LPRF membrane contributes to a successful outcome and acts as a physical barrier against micro-organisms, thus preventing secondary infections.

Role of microbiological culture and polymerase chain reaction (PCR) of actinomyces in medication-related osteonecrosis of the jaw (MRONJ)

We hypothesized that local infection plays a critical role in the pathogenesis of medication-related osteonecrosis of the jaw (MRONJ). Recent developments in molecular methods have revolutionized new approaches for the rapid detection of microorganisms including those difficult to culture. The aim of our study is to identify the bacterial profiles in MRONJ by microbiological culture and polymerase chain reactions (PCR). A retrospective analysis was performed on MRONJ patients from 2008 to 2014. The bacterial profile from MRONJ bone samples was determined using microbiological culture and PCR. Ninety five patients fulfilled the inclusion criteria with mean age of 69.85 ± 8.71 years. A female predilection was detected. The mandible was more commonly affected than maxilla. Tooth extraction was the frequent triggering factor. Breast cancer was the primary cause for administration and intravenous bisphosphonates were the most commonly administrated antiresorptive drugs. The majority of patients were classified as stage 2. Posterior teeth were most commonly affected. Based on bone culture results, the most common microorganism were both actinomyces and mixed flora. PCR confirmed the presence of actinomyces in 55 patients. Our data suggest that PCR might be an innovative method for detection of microorganisms difficult to culture using traditional microbiological techniques.

Extensive Surgical Procedures Result in Better Treatment Outcomes for Bisphosphonate-Related Osteonecrosis of the Jaw in Patients With Osteoporosis

PURPOSE

To identify the risk factors associated with relapse or treatment failure after surgery for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with osteoporosis.

PATIENTS AND METHODS

We performed a retrospective cohort study of BRONJ in patients with osteoporosis who had undergone surgical procedures from 2004 to 2016 at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The predictor variables were a set of heterogeneous variables, including demographic (age, gender), anatomic (maxilla or mandible, or both, affected location), clinical (disease stage, etiology, comorbidities, history of intravenous bisphosphonate intake), time (conservative treatment before surgery, bisphosphonate treatment before the development of BRONJ, discontinuation of the drug before surgery, interval to final follow-up, interval to reoperation in the case of relapse or treatment failure), and perioperative variables (type of anesthesia, type of surgical procedures). The primary outcome variable was relapse after surgery that required reoperation (yes vs no). The descriptive and bivariate statistics were computed to assess the relationships between the study variables and the outcome. To determine the risk factors, we conducted a survival analysis using the Cox model.

RESULTS

The final sample included 325 subjects with a median age of 75 years, and 97% were women. After surgery, 30% of patients did not completely recuperate and underwent repeat surgery. The interval from the first surgery to reoperation ranged from 10 days to 5.6 years. Relapse or treatment failure most often occurred immediately after surgery. The type of surgical procedure and mode of anesthesia were the most important factors in the treatment outcome. A drug holiday did not appear to influence the likelihood of relapse after surgery.

CONCLUSIONS

Treatment of BRONJ in patients with osteoporosis might benefit from more careful and extensive surgical procedures rather than curettage performed with the patient under local anesthesia.

The starting point for bisphosphonate-related osteonecrosis of the jaw: Alveolar bone or oral mucosa? A randomized, controlled experimental study

OBJECTIVE

Although over a decade has passed since first introduction of BRONJ, the exact pathophysiology of this disease is still unclear. The present experimental study aimed to determine whether the oral mucosa or alveolar bone serves as the starting point for BRONJ development.

SUBJECTS AND METHODS

Sixty male Wistar rats were randomly assigned into study and control groups (each, n = 30), and received intraperitoneal injection of 0.06 mg/kg zoledronate and saline, respectively, once a week for 12 weeks. At the end of the week 4 of the experiment, all 60 rats underwent unilateral mandibular first molar extraction. A 4 mm defect was made in the contralateral canine alveolar mucosa. At the end of the experiment, rats were sacrificed, and the three areas of interest including extraction, soft tissue defect, and the non-intervention (canine area on the same side of extraction) sites were assessed clinically for presence of bone exposure/fistula, and histologically for status of bone remodeling (only at extraction site) and osteonecrosis.

RESULTS

In the study group, the frequency of bone exposure/fistula was 80%, 0%, and 0%; and the rate of histological bone necrosis was 83.3%, 20%, and 0%; at the extraction, soft tissue defect, and non-intervention sites, respectively. No clinical and histological sign of bone necrosis was found in the control group. Normal bone remodeling was observed in 0% and 100% of the extraction sockets in the study and control groups, respectively.

CONCLUSION

Injury to alveolar bone was a stronger trigger for BRONJ development compared to oral mucosal damages.

Evaluation of the predisposing factors and involved outcome of surgical treatment in bisphosphonate-related osteonecrosis of the jaw cases including bone biopsies

Objectives

This study examined the statistical relevance of whether the systemic predisposing factors affect the prognosis of surgical treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ). All cases had undergone bone biopsies to determine the characteristics of the mechanisms of BRONJ by optical microscopy.

Materials and Methods

The data included 54 BRONJ cases who underwent surgery and in whom bone biopsies were performed. The results of surgery were evaluated and the results were classified into 3 categories: normal recovery, delayed recovery, and recurrence after surgery. The medical history, such as diabetes mellitus, medication of steroids, malignancies on other sites was investigated for an evaluation of the systemic predisposing factors in relation to the prognosis. The three factors involved with the medication of bisphosphonate (BP) were the medication route, medication period, and drug holiday of BP before surgery. The serum C-terminal cross-linking telopeptide (CTX) value and presence of microorganism colony in bone biopsy specimens were also checked. Statistical analysis was then carried out to determine the relationship between these factors and the results of surgery.

Results

The group of patients suffering from diabetes and on steroids tended to show poorer results after surgery. Parenteral medication of BP made the patients have a poorer prognosis after surgery than oral medication. In contrast, the medication period and drug holiday of BP before surgery did not have significance with the results of surgery nor did the serum CTX value and presence of microorganism colony. Necrotic bone specimens in this study typically showed disappearing new bone formation around the osteocytic lacunae and destroyed Howship's lacunae.

Conclusion

Although many variables exist, this study could in part, predict the prognosis of surgical treatment of BRONJ by taking the patient's medical history.

Therapeutic interactions between mesenchymal stem cells for healing medication-related osteonecrosis of the jaw

Background

Mesenchymal stem cells (MSCs) have been isolated from a variety of tissues, including bone marrow, adipose, and mucosa. MSCs have the capacity for self-renewal and differentiation. Reports have been published on the systemic administration of MSCs leading to functional improvements by engraftment and differentiation, thus providing a new strategy to regenerate damaged tissues. Recently, it has become clear that MSCs possess immunomodulatory properties and can therefore be used to treat diseases. However, the therapeutic effect mechanisms of MSCs are yet to be determined. Here, we investigated these mechanisms using a medication-related osteonecrosis of the jaw (MRONJ)-like mouse model.

Methods

To generate MRONJ-like characteristics, mice received intravenous zoledronate and dexamethasone two times a week. At 1 week after intravenous injection, maxillary first molars were extracted, and at 1 week after tooth extraction, MSCs were isolated from the bone marrow of the mice femurs and tibias. To compare “diseased MSCs” from MRONJ-like mice (d-MSCs) with “control MSCs” from untreated mice (c-MSCs), the isolated MSCs were analyzed by differentiation and colony-forming unit-fibroblast (CFU-F) assays and systemic transplantation of either d-MSCs or c-MSCs into MRONJ-like mice. Furthermore, we observed the exchange of cell contents among d-MSCs and c-MSCs during coculture with all combinations of each MSC type.

Results

d-MSCs were inferior to c-MSCs in differentiation and CFU-F assays. Moreover, the d-MSC-treated group did not show earlier healing in MRONJ-like mice. In cocultures with any combination, MSC pairs formed cell–cell contacts and exchanged cell contents. Interestingly, the exchange among c-MSCs and d-MSCs was more frequently observed than other pairs, and d-MSCs were distinguishable from c-MSCs.

Conclusions

The interaction of c-MSCs and d-MSCs, including exchange of cell contents, contributes to the treatment potential of d-MSCs. This cellular behavior might be one therapeutic mechanism used by MSCs for MRONJ.

Effect of different doses of zoledronic acid in establishing of bisphosphonate-related osteonecrosis

OBJECTIVES

To establish osteonecrosis of the jaws in rats treated with different doses of zoledronic acid (ZA).

METHODS

Male Wistar rats (n=6-7) received three consecutive weekly intravenous ZA infusions at doses of 0.04, 0.20 or 1.00mg/kg ZA or saline (control). Four weeks after the last administration, the animals were submitted to simple extraction of the lower left first molar. An additional dose of ZA was administered seven days later, and the animals were sacrificed 28 days after exodontia. Weight was measured and blood was collected weekly for analysis. The jaw was radiographically and microscopically examined along with the liver, spleen, kidney and stomach.

RESULTS

All ZA doses showed a higher radiolucent area than the control (p<0.0001), but the dose of 0.04mg/kg did not show BRONJ. Doses of 0.20 and 1.00mg/kg ZA showed histological evidence of bone necrosis (p=0.0004). Anaemia (p<0.0001, r(2)=0.8073) and leucocytosis (p<0.0001, r(2)=0.9699) are seen with an increase of lymphocytes (p<0.0001, r(2)=0.6431) and neutrophils and monocytes (p=0.0218, r(2)=0.8724) in all the animals treated with an increasing dose of ZA. Haemorrhage and ectasia were observed in the spleen (p=0.0004) and stomach (p=0.0168) in a dose-dependent manner, and the animals treated with ZA showed a lower rate of weight gain (p<0.0001).

CONCLUSIONS

We designed a bisphosphonate-related osteonecrosis of the jaw model that reproduces radiographic and histological parameters and mimics clinical alterations such as leucocytosis, anaemia and idiosyncratic inflammatory post infusion reactions.