Exposing human epithelial cells to zoledronic acid can mediate osteonecrosis of jaw: an in vitro model

Oral fibroblasts rescue osteogenic differentiation of mesenchymal stem cells after exposure to Zoledronic acid in a paracrine effect

Background: Medication-related osteonecrosis of the jaw is a serious complication that develops in oncologic patients treated with Zoledronic acid. Although used for over 30 years, the influence of Zoledronic acid on bone has been thoroughly investigated, mainly on osteoclasts. While decreasing osteoclast differentiation and function, for many years it was thought that Zoledronic acid increased osteoblast differentiation, thus increasing bone volume. Moreover, despite the influence of soft tissue on the bone healing process, the impact of zoledronic acid on the interaction between soft tissue and bone was not investigated. Aim: Our goal was to investigate the influence of Zoledronic Acid and soft tissue cells on osteogenic differentiation of mesenchymal stem cells (MSCs). Materials and methods: Osteogenic differentiation of MSCs was examined after exposure to Zoledronic Acid. To determine the influence of soft tissue cells on MSCs' osteogenic differentiation, conditioned media from keratinocytes and oral fibroblasts were added to osteogenic medium supplemented with Zoledronic Acid. Proteomic composition of keratinocytes' and fibroblasts' conditioned media were analyzed. Results: Zoledronic Acid decreased osteogenic differentiation of MSCs by seven-fold. The osteogenic differentiation of MSCs was restored by the supplementation of fibroblasts' conditioned medium to osteogenic medium, despite Zoledronic acid treatment. Five osteogenic proteins involved in the TGFβ pathway were exclusively identified in fibroblasts' conditioned medium, suggesting their role in the rescue effect. Conclusion: Oral fibroblasts secrete proteins that enable osteogenic differentiation of MSCs in the presence of Zoledronic Acid.

Bevacizumab and sunitinib mediate osteogenic and pro-inflammatory molecular changes in primary human alveolar osteoblasts in vitro

Antiangiogenic medications target the de novo blood vessel formation in tumorigenesis. However, these novel drugs have been linked to the onset of medication-related osteonecrosis of the jaw (MRONJ). The aim of this in vitro study was to examine the effects of the vascular endothelial growth factor A (VEGFA) antibody bevacizumab (BEV) and the receptor tyrosine kinase inhibitor (RTKI) sunitinib (SUN) on primary human osteoblasts derived from the alveolar bone. Primary human alveolar osteoblasts (HAOBs) were treated with BEV or SUN for 48 h. Cellular metabolic activity was examined by XTT assay. Differentially regulated genes were identified by screening of 22 selected osteogenic and angiogenic markers by quantitative real-time reverse transcriptase polymerase chain reaction (qRT²-PCR). Protein levels of alkaline phosphatase (ALP), collagen type 1, α1 (COL1A1) and secreted protein acidic and cysteine rich (SPARC) were examined by enzyme-linked immunoassay (ELISA). Treatment with BEV and SUN did not exhibit direct cytotoxic effects in HAOBs as confirmed by XTT assay. Of the 22 genes examined by qRT²-PCR, four genes were significantly regulated after BEV treatment and eight genes in the SUN group as compared to the control group. Gene expression levels of ALPL, COL1A1 and SPARC were significantly downregulated by both drugs. Further analysis by ELISA indicated the downregulation of protein levels of ALP, COL1A1 and SPARC in the BEV and SUN groups. The effects of BEV and SUN in HAOBs may be mediated by alterations to osteogenic and catabolic markers. Therapeutic or preventive strategies in MRONJ may address drug-induced depression of osteoblast differentiation.

Medication-Related Osteonecrosis of the Jaws Initiated by Zoledronic Acid and Potential Pathophysiology

The aim of this systematic review is to present an up-to-date review of available publications investigating the cellular mechanisms initiating the development of medication-related osteonecrosis of the jaw caused by zoledronic acid. Electronic searches of MEDLINE/PubMed and Scopus were conducted on the 3 June 2019. A total of 804 publications were identified, of which 11 met the inclusion criteria and were, therefore, included in this study. All the included studies were in vitro studies investigating various human cells. The current review found that zoledronic acid in various concentrations increased apoptosis and decreased migration and proliferation of epithelial cells, fibroblasts, osteoblasts, endothelial cells and dental pulp stem cells, which can affect local tissue homeostasis. The consequences of zoledronic acid were found to be both time- and dose-dependent. The pathophysiology of medication-related osteonecrosis of the jaw is likely a multifactorial process involving prolonged wound healing, chronic inflammation and altered bone remodelling following the administration of zoledronic acid. Further research is needed to identify the exact pathophysiology to optimise management and treatment.

Effects of metformin on the prevention of bisphosphonate-related osteonecrosis of the jaw-like lesions in rats

PURPOSE

In this study, we aimed to investigate the effect of glucose metabolism on bone healing after tooth extraction in an osteoporosis rat model administered zoledronic acid (ZA) and dexamethasone (DX).

METHODS

In total, 24 male Wistar rats (4 weeks old) were randomly assigned to four groups: Control (subcutaneous physiological saline), ZD (subcutaneous ZA and DX twice a week), Ins+ZD (subcutaneous insulin followed by ZD treatment), and Met+ZD (oral metformin followed by ZD treatment). Blood was collected every two weeks . Two weeks after treatment initiation, the first molar tooth on the right maxilla was extracted from all rats. Four weeks later, the rats were sacrificed, and bone healing was assessed. Maxillae samples were fixed and scanned using micro-computed tomography for quantifying areas of bone defects. Hematoxylin-eosin and tartrate-resistant acid phosphatase (TRAP) staining were performed to evaluate bone apoptosis and osteoclast number.

RESULTS

In all experimental groups, body weight was statistically lower than that in the Control group, with no changes observed in uncarboxylated osteocalcin concentrations. The radiological analysis revealed that insulin or metformin administration improved healing in the tooth extraction socket (p < 0.01). Histological examination revealed that the osteonecrosis area was reduced in the Ins+ZD and Met+ZD groups (p < 0.01). TRAP staining presented increased osteoclast numbers in the ZD group when compared with that observed in the Control.

CONCLUSIONS

Tooth extraction with long-term ZA and DX administration inhibited bone remodeling and induced bisphosphonate-related osteonecrosis of the jaw-like lesions. Metformin exerted protective effects ag ainst osteonecrosis of the jaw.

Standardized Arrabidaea chica Extract Shows Cytoprotective Effects in Zoledronic Acid-Treated Fibroblasts and Osteoblasts

INTRODUCTION

Osteonecrosis of the jaw is a condition associated with intraoral ulceration and bone necrosis induced by antiresorptive medications, such as zoledronic acid, a bisphosphonate. Previous data on Arrabidaea chica (H&B.) Verlot wound healing activity prompted the study reported herein on A. chica standardized hydro alcoholic extract in vitro cytoprotective activity data on epithelial and osteoblastic cells exposed to zoledronic acid (ZA).

METHODS

Primary human gingival fibroblasts and murine pre-osteoblasts were treated with ZA 10 µM together with 5 or 10 µg.mL-1 A. chica extract for 24h and 48 h. At both times, cells were submitted to viability assay and caspase 3/7 activation evaluation. Statistical analysis used one-way ANOVA and p=0.05.

RESULTS

In cell viability assay, a drastic damage effect of ZA appeared after 48 h in both epithelial (55.8%) and pre-osteoblastic cells (39.7%). When treated with ZA in combination with A. chica extract, cells showed higher viability values: 74.1%-82.3% for fibroblasts and 66% for pre-osteoblasts. Furthermore, the combined treatment presented lower caspase 3/7 activation in fibroblasts and pre-osteoblasts.

CONCLUSION

At low concentrations, A. chica extract showed promising cytoprotective effects against ZA-induced damage actions; however, further in vitro and in vivo studies are required to establish the mechanism of action.

Antimicrobial photodynamic therapy improves the alveolar repair process and prevents the occurrence of osteonecrosis of the jaws after tooth extraction in senile rats treated with zoledronate

This study evaluated the effects of antimicrobial photodynamic therapy (aPDT) in the alveolar repair of rats with major risk factors for bisphosphonate-related osteonecrosis of the jaws (BRONJ). Senile rats received 0.45 ml of vehicle (VEH and VEH/aPDT) or 0.45 ml of zoledronate (ZOL and ZOL/aPDT) every three days for seven weeks. After three weeks of treatment, the first lower left molar was extracted. VEH/aPDT and ZOL/aPDT were submitted to aPDT on the extraction site at 0, 2 and 4 days postoperatively. Euthanasia was performed 28 days postoperatively and the extraction site was evaluated by clinical, histological, histometric, histochemical and immunohistochemical analysis. ZOL showed tissue repair impairment; lower percentage of newly formed bone tissue (NFBT); higher percentage of non-vital bone tissue (NVBT); fewer mature collagen fibers and increased immunolabeling for tumor necrosis factor (TNFα), interleukin (IL)-1β and IL-6. ZOL/aPDT showed clinical and histological characteristics of the extraction site, percentage of NFBT and percentage of mature collagen fiber similar to VEH. Percentage of NVBT and immunolabeling for inflammatory cytokines in ZOL/aPDT was lower than in ZOL. Immunolabeling for tartarato-resistant acid phosphatase (TRAP) was lower in ZOL and ZOL/aPDT. aPDT in the dental extraction site improves tissue repair process and prevents the occurrence of BRONJ-like lesions after tooth extraction.

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-1β. 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.

Pathogenesis of medication-related osteonecrosis of the jaw: a comparative study of in vivo and in vitro trials

Objective This study was performed to determine whether the results of prevailing in vivo and in vitro studies offer a reliable model for investigation of medication-related osteonecrosis of the jaw (MRONJ). Methods Embase, Medline, and the Cochrane Library were searched for articles published from September 2003 to June 2017 involving experimental approaches to the pathogenesis of MRONJ. In vivo and in vitro trials were analyzed with respect to the scientific question, study design, methodology, and results. Results Of 139 studies, 87, 46, and 6 conducted in vivo, in vitro, and both in vivo and in vitro experiments, respectively. Rats, mice, dogs, minipigs, sheep, and rabbits were the preferred animal models used. Osteoblasts, osteoclasts, fibroblasts, keratinocytes, macrophages, and human umbilical vein endothelial cells were the preferred cell types. Zoledronate, alendronate, ibandronate, and risedronate were the most frequent bisphosphonates used. MRONJ was most reliably induced in minipigs because of the close relationship with human bone physiology. In vitro studies showed that reduced viability, growth, and migration of cells in the bone and soft tissues were causative for MRONJ. Other than exposed jawbone after tooth extraction, no reliable cofactors were found. Conclusion The minipig is the most suitable animal model for MRONJ.

In vivo effects of geranylgeraniol on the development of bisphosphonate-related osteonecrosis of the jaws

BACKGROUND

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a complication of the bisphosphonate (BP) treatment and its pathopysiology is still not fully understood. The existing preventive and treatment options require updates and more attention. Geranylgeraniol (GGOH) so far demonstrated an increased activity and viability of the cells previously treated with zoledronic acid (ZA). The aim of this study was to evaluate the in vivo effects of GGOH on the development of BRONJ.

MATERIALS AND METHODS

A total of 30 male Wistar rats were included in the study, divided into three groups: two experimental groups (EG1 and EG2) and a control group (CG). Rats from EG1 and EG2 were treated with 0,06 mg/kg ZA ip weekly in a duration of five weeks, while CG received saline ip. On the third week all animals underwent extraction of the lower right first molars. The rats from EG2 received a local solution of GGOH in concentration of 5 mM in the socket every day after the tooth extraction. The analyses included clinical evaluation on the wound healing and pathohistological evaluation for presence and level of osteonecrosis.

RESULTS

EG2 showed significantly improved wound healing and tissue proliferation, when compared to EG1. EG2 significantly differed from EG1 and CG (p<0,05) for the presence of microscopical osteonecrosis (80% vs 22,2% vs 0%). Regarding to the number of empty lacunes without osteocytes and the level of necrosis, all groups demonstrated significant differences.

CONCLUSION

Geranylgeraniol in a form of local solution may be a promising option for prevention and treatment of BRONJ.

Evaluation of KGF, EGF, VEGF, bcl-2, IL-6 and ki67 expression in oral epithelium adjacent to bisphosphonate-related osteonecrosis and florid osseous dysplasia: a comparative immunohistochemical study

OBJECTIVE

The aim of this study was to compare the expression of proliferative markers and apoptosis-associated proteins in the oral mucosa adjacent to bone sequestrum associated with osteonecrosis (ON) of the jaws and florid osseous dysplasia (OD).

STUDY DESIGN

Oral mucosal samples derived from surgical procedures performed for treatment of ON and OD (10 cases each) were retrieved. Histologic analysis was done on hematoxylin and eosin-stained slides; immunohistochemical reactions against epidermal growth factor (EGF), keratinocyte growth factor (KGF), vascular endothelial growth factor (VEGF), Bcl-2 protein, interleukin-6 (IL-6), and Ki-67 antigen were performed with the immunoperoxidase technique.

RESULTS

The epithelium was hyperplastic in 60% and 22% of ON and OD samples, respectively. Cytoplasmic EGF and KGF expression; Bcl-2, VEGF, and IL-6 expressions; and the mean epithelial proliferative index were not statistically different between the 2 groups. Membranous EGF expression was more evident in samples showing hyperplastic epithelium.

CONCLUSIONS

Exposure to bisphosphonates did not alter the expression of KGF, EGF, VEGF, Bcl-2, IL-6, and the epithelial proliferating index in comparison with inflamed oral mucosa not exposed to bisphosphonates.

Response of a co-culture model of epithelial cells and gingival fibroblasts to zoledronic acid

Osteonecrosis of the jaw is an adverse effect of bisphosphonates. While the etiopathogenesis of this condition has been investigated, the interactions and effects of bisphosphonates on oral mucosa cells remain unclear. It is hypothesized that cell culture models, such as co-culture or three-dimensional cell culture models, can provide valuable insight. Therefore, the aim of this study was to evaluate the effects of zoledronic acid (ZA) on epithelial cells and gingival fibroblasts in a co-culture model. Briefly, epithelial cells were seeded on transwell inserts and gingival fibroblasts were seeded in the lower well of 24-well plates. The latter were treated with ZA (5 μM) for 24 or 48 h. Cell viability and synthesis of the inflammatory chemokine, CCL2, were subsequently assessed. Data were subjected to statistical analysis with a 5% significance level. In the presence of ZA, the epithelial cells exhibited significant toxicity in both cell culture models and at both time points. However, greater cytotoxicity was observed in the co-culture model. Greater viability for the gingival fibroblasts was also associated with the co-culture model, and ZA-mediated toxicity was observed for the 48 h time point. ZA promoted a significant increase in CCL2 synthesis in both sets of cells, with greater CCL2 synthesis detected in the gingival fibroblasts. However, this effect was diminished in the co-culture model. Taken together, these results confirm the specific response patterns of the cells seeded in the co-culture model and also demonstrate the protective mechanism that is mediated by epithelial/mesenchymal cell interactions upon exposure to ZA.

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.

Alendronate alters osteoblast activities

OBJECTIVE

Due to accumulation in the bone matrix and a half-life of at least 10 years, it is important to understand the cellular impact of bisphosphonates (BPs). This study assessed the effects of alendronate (ALN) on human primary osteoblasts.

MATERIAL AND METHODS

Osteoblasts were incubated with ALN (5, 20 and 100 μM), and both cells and cell culture media were harvested after d 1, 3, 7 or 14. Proliferation was evaluated by ³H-thymidine incorporation and tetrazolium dye (MTT) colorimetric assay, and viability by the lactate dehydrogenase (LDH) activity in the medium. Differentiation was evaluated using protein Luminex multiplex assays and RT-PCR.

RESULTS

ALN had no significant effects on cell viability. The lower concentrations enhanced the proliferation, whereas 100 μM diminished the proliferation. mRNA expression of osteocalcin (OC), alkaline phosphatase (ALP) and α-1 type 1 collagen were reduced, whereas ALN enhanced the expression of leptin mRNA and the secretion of interleukin-8 (IL-8) and regulated on activation normal T cell expressed and secreted (RANTES).

CONCLUSIONS

ALN enhanced the secretion of immune factors from human osteoblasts. Combined with a lower rate of proliferation and a decline in differentiation, this indicates that higher dosages or accumulation may cause undesirable local changes in bone.

Autologous platelet concentrates for bisphosphonate-related osteonecrosis of the jaw treatment and prevention. A systematic review of the literature

PURPOSE

Bisphosphonate related osteonecrosis of the jaw (BRONJ) is an adverse drug reaction consisting of progressive bone destruction in the maxillofacial region of patients under current or previous treatment with a bisphosphonate. Autologous platelet concentrates (APC) demonstrated to enhance bone and soft tissue healing in oral surgery procedures. The present systematic review aimed at evaluating if APC may improve treatment and prevention of BRONJ in patients under bisphosphonate therapy.

METHODS

MEDLINE, Scopus and Cochrane databases were searched using terms like bisphosphonates, osteonecrosis, BRONJ, platelet concentrate, PRP, PRF, PRGF. No language, publication date and study design limitation was set. A hand search of the bibliographies of identified articles was also performed. The primary outcome was recurrence/onset of BRONJ after oral surgery procedures.

RESULTS

Eighteen studies were included, reporting on 362 patients undergoing oral surgery in combination with APC. The adjunct of APC in BRONJ treatment significantly reduced osteonecrosis recurrence with respect to control. APC was associated with a lower BRONJ incidence after tooth extraction, though not significant. Heterogeneity was found regarding bisphosphonate type, clinical indication, treatment duration, triggering factors, study design, follow-up duration, type of APC, outcomes adopted to evaluate treatment success.

CONCLUSION

Though the results of this review must be cautiously interpreted, due to the low evidence level of the studies included, and the limited sample size, they are suggestive of possible benefits of APC when associated with surgical procedures for treatment or prevention of BRONJ. To confirm such indication, prospective comparative studies with a large sample size are urgently needed.

Sinus mucosal thickening in bisphosphonate-related osteonecrosis of the jaws: a case-control study

Osteonecrosis of the jaws is a clinically significant complication of bisphosphonate (BP) medications. Otherwise, the effects of BPs on oral soft tissue or cells remain unknown. The main objective of the present study was to determine whether the presence of sinus mucosal thickening was significantly related to BP-related osteonecrosis of the jaw (BRONJ). A case-control study was conducted on 32 patients who underwent treatment of BRONJ with conventional radiological investigations (panoramic radiographs) and computed tomography. The results indicated that patients with BRONJ had a 5.57-fold greater probability of presenting sinus mucosal thickening than controls. Although the existence of this thickening was more common in patients with advanced-stage disease or low levels of C-telopeptide-cross-linked type I collagen, no significant difference was observed between cases and controls. While considering the limitations inherent in the design and number of cases analyzed in our study, patients with osteonecrosis of the jaw were found to have a 5.57-fold greater probability of presenting sinus mucosal thickening (>3 mm) than healthy subjects.

Preventive oral surgery before bisphosphonate administration to reduce osteonecrosis of the jaws

OBJECTIVES

The intravenous injection of bisphosphonates, currently used for osteoporosis, myeloma, or bone metastases, can cause ONJ especially in consequence of trauma. To avoid trauma during bisphosphonate treatment, preventive oral surgery is recommended. The research aimed to evidence whether inflammatory and osteoclastogenic factors are not induced in oral mucosa after bisphosphonate treatment in patients receiving oral preventive surgery procedure and whether proliferation factors are not inhibited.

PATIENTS AND METHODS

Specimens of oral mucosa were removed from healthy subjects and from patients undergoing preventive oral surgery before bisphosphonate treatment. The expression of cytokines and factors involved in osteoclast activity, cell proliferation, and angiogenesis were examined.

RESULTS

Cytokines and RANK-L levels decreased significantly in mucosa from patients undergoing preventive oral surgery procedure before bisphosphonate treatment in comparison with their levels at the beginning of procedure and also in comparison with the level in patients treated only with bisphosphonates and not developing ONJ; conversely, osteoprotegerin and hydroxymethylglutaryl coenzyme A reductase significantly increased or not changed.

CONCLUSIONS

The results suggest that preventive oral surgery could be able to prevent ONJ due to bisphosphonate treatment: The mucosa is not stimulated by bisphosphonates to cause ONJ, as bisphosphonates are probably not released from the bone.

Bone markers for monitoring efficacy in patients with bone metastases receiving zoledronic acid: a review of published data

Bone metastases occur frequently in patients with advanced solid tumors and can create serious clinical problems that are commonly referred to as skeletal-related events. Although bisphosphonates, especially zoledronic acid, have emerged as an integral determinant of managing metastatic bone disease, their application remains a challenge because of the lack of standardized measures and their side effects. Since factors derived from bone metabolism are potentially useful to measure the efficacy of zoledronic acid, several clinical trials have investigated these bone markers with respect to their monitoring values. The results suggest that a greater decline in bone marker levels is associated with a more reduced incidence of skeletal-related events and a better improvement of symptoms. This review summarizes the available evidence on the clinical use of bone markers in monitoring zoledronic acid in various cancers with bone metastases including breast, prostate and lung cancer.

Histology of the Oral Mucosa in Patients With BRONJ at III Stage: A Microscopic Study Proves the Unsuitability of Local Mucosal Flaps

Background

Bisphosphonate Osteonecrosis of the Jaw (BRONJ) is a newly recognized condition reported in patients treated with aminobisphosphonates (BF). BRONJ is defined as the presence of exposed necrotic alveolar bone that does not resolve over a period of 8 weeks in a patient taking bisphosphonates who has not had radiotherapy to the jaw. Treatment protocols have been outlined, but trials and outcomes of treatment and long-term follow-up data are not yet available. In 2004 an expert panel outlined recommendations for the management of bisphosphonate-associated osteonecrosis of the jaws. Through the histological study of the oral mucosa over the bone necrosis and around the osteonecrosis area in 8 patients affected by BRONJ at III stage, the authors highlight the inappropriateness of the local mucosal flaps to cover the losses of substance of the jaw, BF-related.

Methods

Mucosa tissue was taken from 8 patients, affected by BRONJ, III stage. The samples taken from the mucosa around and over the osteonecrosis area were fixed with formalin and an ematossilina-eosin dichromatic coloring was carried out.

Results

The samples of mucosa showed pathognomonic signs of cell suffering that prove that in these patients using local mucosa flaps is inappropriate.

Conclusions

The authors suggest that only a well vascularized flap as free flap must be used to cover the osteonecrosis area in patients with BRONJ stage III. Because of the structural instability of the mucosa in patients suffering of osteonecrosis Bf related the local flaps are prone to ulceration and to relapse.