Identification of Microbial Biofilms in Osteonecrosis of the Jaws Secondary to Bisphosphonate Therapy

Expert consensus on endodontic therapy for patients with systemic conditions

The overall health condition of patients significantly affects the diagnosis, treatment, and prognosis of endodontic diseases. A systemic consideration of the patient's overall health along with oral conditions holds the utmost importance in determining the necessity and feasibility of endodontic therapy, as well as selecting appropriate therapeutic approaches. This expert consensus is a collaborative effort by specialists from endodontics and clinical physicians across the nation based on the current clinical evidence, aiming to provide general guidance on clinical procedures, improve patient safety and enhance clinical outcomes of endodontic therapy in patients with compromised overall health.

Antiresorptive and anti-angiogenic drug therapy in the pediatric population with reference to medication-related osteonecrosis of the jaw

The objective of this study was to identify the prevalence of osteonecrosis of the jaw in a pediatric population with systemic therapeutic exposure to an antiresorptive, anti-angiogenic, and/or immunomodulating drug (ARAID), and in particular in the subgroup of patients who had undergone invasive dental treatment. This was a retrospective cohort study performed at a single center. The investigation included pediatric patients who had undergone systemic therapy with ARAIDs and who began receiving ARAID therapy at ≤16 years of age. The study included 482 patients who received ARAIDs between January 2011 and January 2021. The most common medication class was bisphosphonates (45.0%), followed by mTOR inhibitors (30.1%) and anti-angiogenics (17.8%). No diagnosis of osteonecrosis of the jaw was observed. From this population, 26 patients were noted to have undergone invasive dental treatment. The duration from treatment to the invasive procedure ranged from 0 to 5.9 years. Medication-related osteonecrosis of the jaw is extremely rare among the pediatric population - much less common when compared to the adult population. Prospective cohort studies and continued evaluation will help determine the incidence and prevalence of medication-related osteonecrosis of the jaw in pediatric patients.

Can medication-related osteonecrosis of the jaw be attributed to specific microorganisms through oral microbiota analyses? A preliminary study

BACKGROUND

Medication-related osteonecrosis of the jaw (MRONJ) can cause significant pain and loss of aesthetics and function if not treated properly. However, diagnosis still relies on detailed intraoral examinations and imaging. Prognosis varies even among patients with similar stages or conditions of MRONJ, emphasizing the need for a deeper understanding of its complex mechanisms. Thus, this study aimed to identify the oral microbiota of patients with MRONJ.

METHODS

This single-center prospective cohort study included patients with confirmed MRONJ who visited the Department of Oral and Maxillofacial Surgery at Yonsei University Dental Hospital between 2021 and 2022. Oral swab samples were collected from the affected and unaffected sides of each patient. The composition and enumeration of the microbial communities were analyzed, and the diversity was compared to verify ecological changes in the groups using a next-generation sequencing-based 16S metagenomic analysis. A statistical analysis was performed using Wilcoxon signed-rank test with SPSS version 22, and values of P less than 0.05 were considered statistically significant.

RESULTS

The final study sample included 12 patients. The mean age was 82.67 ± 5.73 (range, 72-90) years. Changes in microbial composition were observed at different taxonomic levels (phylum, genus, and species). The identified microorganisms were commonly associated with periodontitis, gingival disease, and endodontic infection, suggesting a multifactorial etiology of MRONJ.

CONCLUSIONS

Although this study is based on a small number of cases, it shows that MRONJ is not caused by a specific microorganism but can rather be caused by a variety of factors. By addressing these findings in large-scale studies, the significance of oral microbiome in pathogenesis can be further elucidated and can facilitate the development of effective therapeutic interventions for patients with MRONJ.

Bisphosphonates and Their Connection to Dental Procedures: Exploring Bisphosphonate-Related Osteonecrosis of the Jaws

Bisphosphonates are widely used to treat osteoporosis and malignant tumors due to their effectiveness in increasing bone density and inhibiting bone resorption. However, their association with bisphosphonate-related osteonecrosis of the jaws (BRONJ) following invasive dental procedures poses a significant challenge. This review explores the functions, mechanisms, and side effects of bisphosphonates, emphasizing their impact on dental procedures. Dental patients receiving bisphosphonate treatment are at higher risk of BRONJ, necessitating dentists' awareness of these risks. Topical bisphosphonate applications enhance dental implant success, by promoting osseointegration and preventing osteoclast apoptosis, and is effective in periodontal treatment. Yet, systemic administration (intravenous or intraoral) significantly increases the risk of BRONJ following dental procedures, particularly in inflamed conditions. Prevention and management of BRONJ involve maintaining oral health, considering alternative treatments, and careful pre-operative and post-operative follow-ups. Future research could focus on finding bisphosphonate alternatives with fewer side effects or developing combinations that reduce BRONJ risk. This review underscores the need for further exploration of bisphosphonates and their implications in dental procedures.

Effect of agents affecting bone homeostasis on short- and long-term implant failure

OBJECTIVES

To review the current evidence on the relationship between agents that affect bone homeostasis and dental implant failures.

MATERIALS AND METHODS

Electronic searches for bisphosphonates, denosumab, methotrexate, corticosteroids, romosozumab, sunitinib, and bevacizumab were performed using PubMed, MEDLINE (OVID), EMBASE (OVID), Cochrane Central Register of Controlled Trials (Cochrane Library), Cochrane Oral Health Group Trials Register (Cochrane Library) and Web of Science (Thomson Reuters). Manual searches were also conducted to complement the digital searches for recent issues.

RESULTS

Previous publications suggested that bisphosphonates do not compromise the survival of dental implants. However, one study documented an increased risk of implant failure in patients who had received high-dose of intravenous bisphosphonate therapy after implant rehabilitation. There has been an issue of MRONJ around implants in patients who have successfully received implant therapy before and after antiresorptive therapy, leading to late implant failure. Despite evidence on the detrimental effects of denosumab, methotrexate and corticosteroids on bone metabolism, their role in implant survival is not conclusive.

CONCLUSIONS

At present, there is insufficient evidence to establish a potential connection between agents that affects bone homeostasis and implant failure. However, some studies have reported negative results for implant therapy. In addition, implant-related sequestration in patients who received anti-resorptive therapy, despite of successful osseointegration, is also noticeable. Although limited studies are available at present, clinicians should still carefully consider the potential hazards and take appropriate precautions to minimize the risks associated with the medications and implant therapy.

Pathophysiology of Medication-Related Osteonecrosis of the Jaw-A Minireview

Medication-related osteonecrosis of the jaw (MRONJ) is a rare but serious adverse effect of antiresorptive medications administered for control of osseous malignancy, osteoporosis, or other bone metabolic diseases. Despite being reported in the literature two decades ago, MRONJ etiology, pathophysiology, and progression remain largely unknown, and current nonoperative or operative treatment strategies are mostly empirical. Several hypotheses that attempt to explain the mechanisms of MRONJ pathogenesis have been proposed. However, none of these hypotheses alone is able to capture the complex mechanistic underpinnings of the disease. In this minireview, we aim to highlight key findings from clinical and translational studies and propose a unifying model for the pathogenesis and progression of MRONJ. We also identify aspects of the disease process that require further investigation and suggest areas for future research efforts toward calibrating methodologic approaches and validating experimental findings. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Intermittent parathyroid hormone enhances the healing of medication-related osteonecrosis of the jaw lesions in rice rats

Medication-related osteonecrosis of the jaw (MRONJ) is a potentially severe adverse event in patients treated with antiresorptives. Management of MRONJ is challenging, and no non-antibiotic, established medical treatment exists. Intermittent parathyroid hormone (iPTH) has been used off-label to treat MRONJ with favorable results. However, its medical efficacy has rarely been substantiated in clinical or preclinical experiments. Using a validated rice rat, infection-based model of MRONJ, we evaluated the effects of iPTH on established MRONJ. We hypothesize that iPTH contributes to MRONJ resolution by enhancing alveolar bone turnover and healing oral soft tissues. Eighty-four rice rats began a standard rodent chow diet at age 4 weeks to induce localized periodontitis. Rats were simultaneously randomized to receive saline (vehicle, VEH) or zoledronic acid (ZOL, 80 μg/kg IV) every 4 weeks. Oral exams were conducted bi-weekly to assign a gross quadrant grade (GQG, 0-4) to evaluate any lesion at the lingual aspect of the interdental space between maxillary molar (M2) and M3. 14 of 20 VEH-treated rice rats (70%) developed maxillary localized periodontitis with GQG 2-3 after 30 ± 10 weeks of saline. Additionally, 40 of 64 ZOL-treated rice rats with periodontitis developed MRONJ-like lesions after 30 ± 10 weeks of ZOL treatment. Rice rats with localized periodontitis or MRONJ-like lesions were treated with saline or iPTH (40 μg/kg) subcutaneously (SC) 3 times/week For 6 weeks until euthanasia. We found that iPTH -treated ZOL rats had a lower prevalence of MRONJ (p < 0.001), with lower severity extent of oral lesions (p = 0.003) and percentage of empty osteocyte lacunae (p < 0.001). ZOL rats treated with iPTH displayed a higher osteoblast surface (p < 0.001), more osteoblasts (p < 0.001), higher osteoclast surface (p < 0.001) and more osteoclasts (p = 0.002) at alveolar bone surfaces than ZOL/VEH rats. Greater gingival epithelial thickness and epithelial cell proliferation rate was found in the oral mucosa and gingiva of ZOL/PTH rats than in ZOL/VEH rats (p < 0.001). Our data suggest that iPTH is an efficacious non-operative medicinal therapy that accelerates oral healing and enhances the resolution of MRONJ lesions in ZOL-treated rice rats.

A Study of Oral Health Parameters and the Properties and Composition of Saliva in Oncological Patients with and without Medication-Related Osteonecrosis of the Jaw Who Take Bisphosphonates

Background and Objectives: The aim of this study was to examine how the status of the oral cavity, composition and properties of saliva change in oncological patients with and without Medication-Related Osteonecrosis of the Jaw (MRONJ) undergoing bisphosphonate therapy. Materials and Methods: A retrospective case-control study of 49 oncological patients using bisphosphonates (BPs) was conducted. The study population was divided into two groups-Group I consisted of 29 patients with MRONJ and Group II of 20 patients without MRONJ. The control group consisted of 32 persons without oncological history and without antiresorptive therapy. Standard dental examination included the assessment of the number of teeth remaining, teeth with caries and fillings, Approximal Plaque Index (API) and Bleeding on Probing (BOP). In terms of MRONJ, localization and stage were assessed. Laboratory tests of saliva included determination of pH and concentrations of Ca and PO₄ ions, total protein, lactoferrin, lysozyme, sIgA, IgA, cortisol, neopterin, activity of amylase at rest, and stimulated saliva. The buffering capacity and microbiological tests (Streptococcus mutans, Lactobacillus spp. load) of stimulated saliva were also determined. Results: There were no statistically significant differences between the selected oral parameters and saliva of Group I and Group II. Significant differences were found between Group I and the control group. BOP, lysozyme and cortisol concentration were higher, while the number of teeth with fillings, Ca and neopterin concentrations were lower in comparison to the control group. In Group I, a significantly higher percentage of patients with a high colony count (>10⁵) of Streptococcus mutans and Lactobacillus spp. was also found. The significant differences between Group II and the control group concerned the concentrations of lysozyme, Ca ions, sIgA, neopterin and the colony count of Lactobacillus spp. In the Group I patients who received a significantly higher cumulative dose of BP compared to the Group II, a significant positive correlation was found between the received BP dose and the BOP. Most MRONJ foci were stage 2 and were mainly located in the mandible. Conclusions: Among oncological patients with and without MRONJ undergoing BP therapy compared to the control group, there are statistically significant differences in the dental, periodontal and microbiological status and in the composition of the saliva. Particularly noteworthy are the statistically significant differences in the decreased level of Ca ions, the increased level of cortisol and the elements of saliva related to the immune response (lysozyme, sIgA, neopterin). Additionally, a higher cumulative dose of BPs may affect the susceptibility to the development of osteonecrosis of the jaws. Patients undergoing antiresorptive therapy should receive multidisciplinary medical care, including dental care.

Medication-Related Osteonecrosis: Why the Jawbone?

Medication-related osteonecrosis of the jaw (MRONJ) has emerged as a complication of anti-resorptive medications. Despite its low incidence rate, this problem has gained attention in recent years due to its devastating consequences and lack of preventive strategy. The fact that MRONJ incidence has been exclusive to the jawbones, despite the systemic effect of anti-resorptive medications, could be a starting point to unravel the multifactorial pathogenesis of this condition. This review aims to negotiate the question of why the jawbone is more susceptible to MRONJ than other skeletal sites. Approaching the problem from this perspective could provide new directions for the prevention of MRONJ and expand our understanding of the unique oral microenvironment.

The "Phoenix Jaw" Phenomenon Revisited: Two Cases of Bisphosphonate-Related Mandible Osteonecrosis Surgically Treated with Complete Bone Regeneration

Bisphosphonate-related osteonecrosis of the jaws represents a well-recognized complication occurring in patients being administered drugs for the treatment of osteoporosis and/or malignant disease. Treatment of this condition, aiming to alleviate the symptoms and restore functional status, represents a challenge for the maxillofacial surgeon. Conservative management has been proposed for early stages of this condition, while surgical intervention is mandatory for advanced disease. Two cases of severe bisphosphonate-related osteonecrosis of the jaw that achieved complete osseous recontouring after partial mandibulectomy, are presented.

Porphyromonas gingivalis Induces Bisphosphonate-Related Osteonecrosis of the Femur in Mice

One of the most prominent characteristics of bisphosphonate-related osteonecrosis of the jaw(BRONJ) is its site-specificity. Osteonecrosis tends to occur specifically in maxillofacial bones, in spite of a systemic administration of the medicine. Previous studies suggested rich blood supply and fast bone turnover might be reasons for BRONJ. Yet, a sound scientific basis explaining its occurrence is still lacking. The present study aimed to explore the role of Porphyromonas gingivalis (P. gingivalis), an important oral pathogen, on the site-specificity of bisphosphonate-induced osteonecrosis and to elucidate its underlying mechanism. Mice were intraperitoneally injected with zoledronic acid (ZA) or saline for 3 weeks. In the third week, the right mandibular first molars were extracted and circular bone defects with a diameter of 1 mm were created in right femurs. After the operation, drug administration was continued, and P. gingivalis suspension was applied to the oral cavities and femur defects. The mice were killed after four or eight weeks postoperatively. The right mandibles and femurs were harvested for micro-CT and histological analyses. A poor healing of bone defects of both jaws and femurs was noted in mice injected with both ZA and P. gingivalis. Micro-CT analysis showed a decreased bone volume, and histological staining showed an increased number of empty osteocyte lacunae, a decreased collagen regeneration, an increased inflammatory infiltration and a decreased number of osteoclasts. In addition, the left femurs were collected for isolation of osteoclast precursors (OCPs). The osteoclastogenesis potential of OCPs was analyzed in vitro. OCPs extracted from mice of ZA-treated groups were shown to have a lower osteoclast differentiation potential and the expression level of related genes and proteins was declined. In conclusion, we established a mouse model of bisphosphonate-related osteonecrosis of both the jaw and femur. P. gingivalis could inhibit the healing of femur defects under the administration of ZA. These findings suggest that P. gingivalis in the oral cavity might be one of the steering compounds for BRONJ to occur.

Osteonecrosis of the Jaw and Antiresorptive Agents in Benign and Malignant Diseases: A Critical Review Organized by the ECTS

CONTEXT

Antiresorptive therapy significantly reduces fracture risk in patients with benign bone disease and skeletal-related events (SREs) in patients with bone metastases (BM). Osteonecrosis of the jaw (ONJ) is a rare but severe condition manifested as necrotic bone lesion or lesions of the jaws. ONJ has been linked to the use of potent antiresorptive agents, termed medication-related ONJ (MRONJ).

OBJECTIVE

We aimed to identify the differences various aspects of MRONJ among distinct patient categories and provide recommendations on how to mitigate the risk and optimally manage MRONJ in each of them.

METHODS

A working group of the European Calcified Tissue Society (ECTS) and 2 experts performed an updated detailed review of existing literature on MRONJ incidence, characteristics, and treatment applied in bone diseases with variable severity of skeletal insult, ranging from osteoporosis to prevention of cancer treatment-induced bone loss and SREs in cancer patients with BM.

RESULTS

The risk for MRONJ is much higher in patients with advanced malignancies compared to those with benign bone diseases because of the higher doses and more frequent administration of antiresorptive agents in individuals with compromised general health, along with coadministration of other medications that predispose to MRONJ. The overall risk for MRONJ is considerably lower than the benefits in all categories of patients.

CONCLUSION

The risk for MRONJ largely depends on the underlying bone disease and the relevant antiresorptive regimen applied. Physicians and dentists should keep in mind that the benefits of antiresorptive therapy far outweigh the risk for MRONJ development.

Indigenous microbiota protects development of medication-related osteonecrosis induced by periapical disease in mice

Bacterial infection is a common finding in patients, who develop medication-related osteonecrosis of the jaw (MRONJ) by the long-term and/or high-dose use of anti-resorptive agents such as bisphosphonate (BPs). However, pathological role of bacteria in MRONJ development at the early stage remains controversial. Here, we demonstrated that commensal microbiota protects against MRONJ development in the pulp-exposed periapical periodontitis mouse model. C57/BL6 female mice were treated with intragastric broad-spectrum antibiotics for 1 week. Zoledronic acid (ZOL) through intravenous injection and antibiotics in drinking water were administered for throughout the experiment. Pulp was exposed on the left maxillary first molar, then the mice were left for 5 weeks after which bilateral maxillary first molar was extracted and mice were left for additional 3 weeks to heal. All mice were harvested, and cecum, maxilla, and femurs were collected. ONJ development was assessed using μCT and histologic analyses. When antibiotic was treated in mice, these mice had no weight changes, but developed significantly enlarged ceca compared to the control group (CTL mice). Periapical bone resorption prior to the tooth extraction was similarly prevented when treated with antibiotics, which was confirmed by decreased osteoclasts and inflammation. ZOL treatment with pulp exposure significantly increased bone necrosis as determined by empty lacunae and necrotic bone amount. Furthermore, antibiotics treatment could further exacerbate bone necrosis, with increased osteoclast number. Our findings suggest that the commensal microbiome may play protective role, rather than pathological role, in the early stages of MRONJ development.

Medication-related osteonecrosis of the jaw: An update

Antiresorptive medications, such as bisphosphonates and denosumab, are an important class of medication used to treat a wide range of diseases from osteoporosis to multiple myeloma. Unfortunately, they are also associated with a rare but devastating side effect – medication-related osteonecrosis of the jaw (MRONJ). First reported in 2003, much research has been done into the area; however, the exact pathophysiology continues to elude clinicians and researchers. What has been ascertained is that intravenous treatment, duration of treatment, and tooth extraction are major risk factors. Staging and treatment guidelines have been proposed; however, there has been no universal acceptance, and clinicians rely on various position papers. Over the next 30 years, the aging population is set to double, and with it, the prescription of antiresorptive medication and incidence of MRONJ will undoubtedly increase. In 2013, Gupta et al. published a paper on bisphosphonate-related osteonecrosis of the jaw; however, there have many changes since then. This paper aims to provide a succinct update on those changes.

Effects of Soft Tissue Closure on Medication-Related Osteonecrosis of the Jaw in a Rabbit Model with Tooth Extraction: A Pilot Study

Objectives

The study investigated the effect of soft tissue closure after tooth extraction on the prevention of medication-related osteonecrosis of the jaw in a rabbit model.

Materials and Methods

Twenty female New Zealand white rabbits were randomly assigned into the experimental group administrated with zoledronic acid (ZA) and control groups treated with saline. Bilateral lower premolar extraction was performed 4 weeks after ZA/saline administration. Immediately after extraction, the wound on the right mandible was closed by suture while the other side was left open. Animals were sacrificed 4 weeks and 8 weeks after tooth extraction. Fluorochrome labeling solutions were injected subcutaneously to evaluate the bone growth rates. The mandibles were harvested and subjected for microcomputed tomography, confocal microscope, and histomorphological examinations.

Results

All extraction sites healed well without any signs of infection. Trabecular thickness (Tb.Th) was significantly higher in the ZA-treated group than in the control group at both week 4 and week 8, while no significant difference was detected in the rest of the assessed parameters. The bone growth rate in mandibles showed gradual reduction in the ZA-treated group. Histological analysis showed that at week 8, the animals in the ZA-treated group had significantly higher incidence of osteonecrosis than that in the control group, while no significance was revealed between the sutured and nonsutured side.

Conclusions

ZA treatment significantly reduces bone growth rates but does not reveal a significant effect on bone mineral density and bone microarchitecture. Soft tissue closure of the extraction socket does not reduce the incidence of ONJ in the ZA-treated rabbit model.

Matrix-Bound Zolzoledronate Enhances the Biofilm Colonization of Hydroxyapatite: Effects on Osteonecrosis

(1) Background: The aim of this study was to test whether matrix-bound zoledronate (zol) molecules enhanced the oral biofilm colonization of a mineralized matrix, rendering the alveolar bone more susceptible to medication-related osteonecrosis of the jaw (MRONJ) following invasive dental procedures. (2) Methods: We tested the effect of matrix-bound zol on the growth and attachment of Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn) and Actinomyces israelii (Ai), and whether the nitrogen-containing component of zol contributed to such effect. The role of oral bacteria in the induction of osteonecrosis was then tested using an extra-oral bone defect model. (3) Results: The attachment of biofilm to hydroxyapatite discs increased when the discs were pre-treated with zol. Bacterial proliferation was not affected. Matrix-bound zol was more potent than non-nitrogen-containing etidronate in enhancing the colonization. Stimulation was dampened by pre-treating the bacteria with histidine. The delivery of oral biofilm to a tibial defect caused osteonecrosis in zol-treated rats. (4) Conclusions: We conclude that matrix-bound zol enhances the oral biofilm colonization of hydroxyapatite. This enhancement depended on the presence of the nitrogen-containing group. The oral biofilm rendered the extra-oral bone susceptible to medication-related osteonecrosis, suggesting that it has an important role in the induction of MRONJ.

Effect of polyhexanide as antiseptic mouth rinse against oral pathogens in an in vitro biofilm model

OBJECTIVE

The aim of this study was to evaluate the anti-biofilm effect of polyhexanide mouth rinses against oral pathogens in vitro.

MATERIAL AND METHODS

Biofilms of Candida albicans, Streptococcus mutans, Actinomyces naeslundii, Aggregatibacter actinomycetemcomitans, methicillin-resistant Staphylococcus aureus and Fusobacterium nucleatum were grown on 10 mm diameter hydroxyapatite discs for 5 days. Biofilms were exposed to test substances for 30 s (ProntOral, polyhexanide 0.15%, chlorhexidine 0.2%). Another test set simulating blood contamination in the oral cavity was performed by submerging the discs in defibrinated sheep blood prior to antimicrobial exposure. Biofilm mass was determined via crystal violet staining. The proliferation potency of the cells after antimicrobial exposure was evaluated by plating serially diluted suspensions from extracted biofilms on agar plates and determining the number of colony-forming units (CFU/ml). Mann-Whitney-U, Kruskal-Wallis and Dunn's test were used for statistical analyses.

RESULTS

Regardless of blood contamination ProntOral led to a significant reduction of biofilm mass in all strains. Chlorhexidine and polyhexanide reduced biofilm mass in five out of six strains and in only four strains after blood contamination. All agents significantly reduced CFU/ml from S. mutans, A. actinomycetemcomitans and F. nucleatum biofilms. C. albicans and S. aureus biofilms were only affected by ProntOral and polyhexanide. None of the antiseptics significantly reduced the CFU/ml for A. naeslundii biofilms. After blood contamination ProntOral and polyhexanide significantly reduced CFU/ml in all strains, whereas CHX tended to increase the CFU/ml.

CONCLUSIONS

Polyhexanide mouth rinses seem to be suitable disinfectants against oral pathogens without their anti-biofilm potential being impaired by blood.

Conservative Management of Severe Medication-Related Osteonecrosis of the Jaw With Pathological Fracture

ABSTRACT

Medication-related osteonecrosis of the jaw (MRONJ) is a well-known risk following dental extraction in patients taking certain medications. Pathological fracture secondary to MRONJ often requires complex operative intervention.This case demonstrates the conservative management of pathological fracture secondary to MRONJ in a patient with multiple comorbidities. The patient developed MRONJ with pathological fracture following extraction of the mandibular second molar. The patient presented with significant surgical risk factors, having hypertension and a recent stroke, causing dense left hemiparesis, subsequently resulting in transition to high-level nursing care. Given the high risk of reconstructive surgery, nonoperative management was undertaken. Following a course of long-term antibiotics with resolution of signs of infection, the case was managed conservatively with chlorhexidine-based mouthwash and soft diet.With routine clinico-radiographic assessment and optimal oral health care, the pathological fracture did not require operative intervention. Healing progressed well with no clinical complications and radiographic evidence of good healing at 6- and 12-month follow-up on orthopantomogram.A role for conservative management of pathological fractures secondary to MRONJ yet exists, especially in the elderly population. This case highlights the importance of developing treatment plans based on individual patient context and clinical assessment.

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.

Prospective Observational Study of Bisphosphonate-Related Osteonecrosis of the Jaw in Multiple Myeloma: Microbiota Profiling and Cytokine Expression

PURPOSE

Define incidence and risk factors of osteonecrosis of the jaw (ONJ) and explore oral microbial signatures and host immune response as reflected by cytokine changes in saliva and serum in multiple myeloma (MM) patients on bisphosphate (BP) therapy.

PATIENTS AND METHODS

A single center observational prospective study of MM patients (n = 110) on >2 years of BP, none had ONJ at enrollment. Patients were followed every 3 months for 18 months with clinical/dental examination and serial measurements of inflammatory cytokines, bone turnover markers, and angiogenic growth factors. Oral microbiota was characterized by sequencing of 16S rRNA gene from saliva.

RESULTS

Over the study period 14 patients (13%) developed BRONJ, at a median of 5.7 years (95% CI: 1.9-12.0) from MM diagnosis. Chronic periodontal disease was the main clinically observed risk factor. Oral microbial profiling revealed lower bacterial richness/diversity in BRONJ. Streptococcus intermedius, S. mutans, and S. perioris were abundant in controls; S. sonstellatus and S anginosus were prevalent in BRONJ. In the saliva, at baseline patients who developed BRONJ had higher levels of MIP-1β; TNF-α and IL-6 compared to those without BRONJ, cytokine profile consistent with M-1 macrophage activation. In the serum, patients with BRONJ have significantly lower levels of TGF beta and VEGF over the study period.

CONCLUSION

Periodontal disease associated with low microbial diversity and predominance of invasive species with a proinflammatory cytokine profile leading to tissue damage and alteration of immunity seems to be the main culprit in pathogenesis of BRONJ.

Clinical considerations for medication-related osteonecrosis of the jaw: a comprehensive literature review

Background

Medication-related osteonecrosis of the jaw (MRONJ), which was first reported as bisphosphonate-related osteonecrosis of the jaw (BRONJ) in bisphosphonate users, is a rare but severe soft and hard tissue disease induced by several types of medications. There has been a deluge of information about MRONJ, such as epidemiology, risk factors, clinical recommendations for dental treatment to prevent it, and treatment strategies in medication-prescribed users. The aim of this study was to comprehensively review recent articles and provide the current scientific information about MRONJ, especially clinical considerations or recommendations for dental treatment to prevent its occurrence.

Materials and methods

The current literature review was mainly based on 14 systematic reviews with or without meta-analysis, 4 position papers, 1 consensus statement, 1 clinical guideline, and 2 clinical reviews regarding MRONJ after a PubMed database and manual searches according to inclusion and exclusion criteria. Moreover, 53 articles were selected by manual search in regard to all references from selected articles and other articles identified on the PubMed search, irrespective of publication date, and inclusion and exclusion criteria.

Results

The incidence and prevalence of MRONJ are relatively low, although they are clearly higher in cancer patients receiving high-dose antiresorptive agents or angiogenesis inhibitors rather than osteoporosis patients receiving oral bisphosphonates or denosumab. There are many types of local, systemic, and other risk factors for the development of MRONJ. Clinical recommendations are provided for each clinical situation of patients to prevent MRONJ. There are also treatment strategies for MRONJ in each stage.

Conclusions

General dentists should perform appropriate dental treatment to prevent MRONJ in the patients prior to or when receiving medications that could induce MRONJ. Moreover, there are treatment strategies for MRONJ in each stage that oral surgeons could follow. Adequate and updated clinical information regarding MRONJ based on scientific data is required whenever possible.

Complementarity of Photo-Biomodulation, Surgical Treatment, and Antibiotherapy for Medication-Related Osteonecrosis of the Jaws (MRONJ)

Background and Objectives: Antiresorptive or anti-angiogenic agents may induce medication-related osteonecrosis of the jaws (MRONJ), which represents a challenge for clinicians. The aim of this study is to design and apply a composed and stage-approach therapy combining antibiotherapy, surgical treatment, and photo-biomodulation (PBM) for the prevention or treatment of MRONJ lesions. Materials and Methods: The proposed treatment protocol was carried out in the Department of Oral & Maxillofacial Surgery of the “Victor Babes” University of Medicine and Farmacy of Timisoara, in 2018–2020. A total of 241 patients who were previously exposed to antiresorptive or anti-angiogenic therapy, as well as patients already diagnosed with MRONJ at different stages of the disease were treated. A preventive protocol was applied for patients in an “at risk” stage. Patients in more advanced stages received a complex treatment. Results: The healing proved to be complete, with spontaneous bone coverage in all the n = 84 cases placed in an “at risk” stage. For the n = 49 patients belonging to stage 0, pain reductions and decreases of mucosal inflammations were also obtained in all cases. For the n = 108 patients proposed for surgery (i.e., in stages 1, 2, or 3 of MRONJ), a total healing rate of 91.66% was obtained after the first surgery, while considering the downscaling to stage 1 as a treatment “success”, only one “failure” was reported. This brings the overall “success” rate to 96.68% for a complete healing, and to 99.59% when downscaling to stage 1 is included in the healing rate. Conclusions: Therefore, the clinical outcome of the present study indicates that patients with MRONJ in almost all stages of the disease can benefit from such a proposed association of methods, with superior clinical results compared to classical therapies.

Concentration of Penicillin G in Jawbone Affected by Antiresorptive Agent-Related Osteonecrosis Following a Single Preoperative Dose

The aim of this study was to evaluate the concentration of penicillin G in bone affected by antiresorptive agent-related osteonecrosis of the jaw (ARONJ) following a single preoperative dose of 10 million international units (6000 mg). ARONJ is a major concern in patients administered antiresorptive agents for conditions associated with pathologically increased bone resorption. Antibiotic therapy is a key component of most treatment approaches for ARONJ and penicillin based regimens, providing a cost effective therapy option with a favorable side effect profile, are administered most frequently. In this study, high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) was applied to evaluate penicillin G concentration in serum and bone samples of 19 patients suffering from ARONJ and undergoing surgical treatment under perioperative intravenous (IV) antibiotic therapy. Penicillin G bone concentrations were above the limit of detection (0.1 μg/g bone tissue) in 16 out of 19 samples, with a median concentration of 2.7 μg/g (range 0.1–8.8 μg/g). Penicillin G concentrations in intraoperative serum samples were above the limit of detection in all serum samples, with a median concentration of 116 μg/mL (range 1–232 μg/mL). Thus, considering bacteria frequently found in ARONJ lesions, penicillin G at levels providing adequate antimicrobial activity was detected in the serum and 16 out of 19 osteonecrotic lesions of patients suffering from ARONJ.

Actinomyces and MRONJ: A retrospective study and a literature review

The AAOMS in 2014 changed from BRONJ to the term Medication-Related Osteonecrosis of the Jaw (MRONJ), because of the growing number of osteonecrosis cases associated with other antiresorptive and antiangiogenic therapies. Even if the drugs involved are different, the histopathological findings are the same. Colonies of Actinomyces are encountered in most cases. The aim of the present study is to report on Actinomyces prevalence among the cases of MRONJ, taking into consideration also antiresorptive and antiangiogenic therapies in the literature and in our sample between 2005 and 2020. The review was performed using the database Medline the linkage between Actinomyces infection and MRONJ. The retrospective study was conducted on patients between with clinical and radiological manifestations of MRONJ May 2005 and February 2020. A total of 42 articles were found, 30 publications have been taken into consideration for the review. A total of 114 patients have been examined at the Padua Hospital. A total of 101 oncological patients presented the histological confirmation of MRONJ. 83 specimens revealed the presence of Actinomyces infection (82.18%). Actinomyces-associated lesions are frequent and present a wide spectrum of clinical manifestation.

Medication-Related Osteonecrosis of the Jaws

Medication-related osteonecrosis of the jaw is an oral complication in cancer patients being treated with either antiresorptive or antiangiogenic drugs. The first reports of MRONJ were published in 2003. Hundreds of manuscripts have been published in the medical and dental literature describing the complication, clinical and radiographic signs and symptoms, possible pathophysiology, and management. Despite this extensive literature, the pathobiological mechanisms by which medication-related osteonecrosis of the jaw develops have not yet been fully delineated. The aim of this manuscript is to present current knowledge about the complication ragarding to the definition, known risk factors, and clinical management recommendations. Based on this current state of the science, we also propose research directions that have potential to enhance the management of future oncology patients who are receiving these agents.

Replacing one evil with another: Is the fibula really a dispensable spare part available for transfer in patients with medication-related osteonecrosis of the jaws?

Because of the long-term and consecutive use of different causative agents, clinicians are increasingly encountering patients needing restoration of the stomatognathic system after surgical resection of highly advanced necroses of the jaw. For plastic restoration in these cases, microvascular reconstruction seems to represent the most viable option. According to the limited data available, the risks of this operation are considered comparable with those faced by other patient cohorts. We report here the case of a patient who suffered 2 successive pathologic fractures of the tibia after microsurgical reconstruction of the mandible with a free fibula flap. This exemplifies a general problem, especially because the patient also suffered from a treatment-refractory infection of the transplanted bone. Although the present literature indicates otherwise, fibula transplants might not be the gold standard in these cases. Therefore, alternatives to transplants from the weight-bearing parts of the body need to be considered until more data are available.

Indigenous Microbiota Protects against Inflammation-Induced Osteonecrosis

Medication-related osteonecrosis of the jaw (MRONJ) is a rare intraoral lesion that occurs in patients undergoing long-term and/or high-dose therapy with nitrogen-containing bisphosphonates, a RANKL inhibitor, antiangiogenic agents, or mTOR inhibitors. The presence of pathogenic bacteria is highly associated with advanced stages of MRONJ lesions; however, the exact role of indigenous microbes in MRONJ development is unknown. Here, we report that the normal oral flora in mice protects against inflammation-induced osteonecrosis. In mice that developed osteonecrosis following tooth extraction, there was increased bacterial infiltration when compared with healed controls. Antibiotic-mediated oral dysbiosis led to a local inhibition of bone resorption in the presence of ligature-induced periodontitis (LIP). There was no significant difference in empty lacunae, necrotic bone formation, osteoclast number, and surface area in antibiotic-treated as compared with conventionally colonized mice following extraction of healthy teeth after zoledronic acid infusions. However, extraction of LIP teeth led to increased empty lacunae, necrotic bone, and osteoclast surface area in antibiotic- and zoledronic acid-treated mice as compared with conventionally colonized mice. Our findings suggest that the presence of the indigenous microbiota protects against LIP-induced osteonecrosis.

Saliva diagnostics in patients suffering from bisphosphonate-associated osteonecrosis of the jaw: Results of an observational study

OBJECTIVE

One of the severe side effects of bisphosphonate (BP) therapy is bisphosphonate-associated osteonecrosis of the jaw (BONJ). However, there is no information available about its pathogenesis. Hence, the aim of this observational study was to contribute to discerning this pathogenesis by comparing salivary quantity and quality in patients with BONJ and undergoing BP treatment.

MATERIALS AND METHODS

This study included 60 patients divided into three groups. The first group consisted of 20 patients with established BONJ, the second group had 20 patients undergoing BP treatment, and the third group comprised 20 healthy individuals. These groups were analysed for the flow rate of stimulated saliva, buffer capacity, and salivary pH level.

RESULTS

Reduced salivation was observed in a significantly high number of patients with established BONJ (n = 8) and those undergoing BP treatment (n = 9) in comparison with the healthy control group (n = 4; p = 0.039). Though the distribution of the mean value of stimulated saliva flow rates in patients undergoing BP treatment was lower than in the control group, the difference was not significant. Moreover, there were no significant differences in the salivary pH level and buffer capacity in patients undergoing BP treatment as compared with the healthy control group.

CONCLUSIONS

It is possible that the quantity of human saliva is affected by BP treatment. This reduction in saliva production could have a negative effect on mucosal health and is perhaps a cofactor in the pathogenesis of BONJ.

Role of dendritic cell-mediated immune response in oral homeostasis: A new mechanism of osteonecrosis of the jaw

Dendritic cells are an important link between innate and adaptive immune response. The role of dendritic cells in bone homeostasis, however, is not understood. Osteoporosis medications that inhibit osteoclasts have been associated with osteonecrosis, a condition limited to the jawbone, thus called medication-related osteonecrosis of the jaw. We propose that disruption of the local immune response renders the oral microenvironment conducive to osteonecrosis. We tested whether zoledronate (Zol) treatment impaired dendritic cell (DC) functions and increased bacterial load in alveolar bone in vivo and whether DC inhibition alone predisposed the animals to osteonecrosis. We also analyzed the role of Zol in impairment of differentiation and function of migratory and tissue-resident DCs, promoting disruption of T-cell activation in vitro. Results demonstrated a Zol induced impairment in DC functions and an increased bacterial load in the oral cavity. DC-deficient mice were predisposed to osteonecrosis following dental extraction. Zol treatment of DCs in vitro caused an impairment in immune functions including differentiation, maturation, migration, antigen presentation, and T-cell activation. We conclude that the mechanism of Zol-induced osteonecrosis of the jaw involves disruption of DC immune functions required to clear bacterial infection and activate T cell effector response.

Gingival fibroblasts and medication-related osteonecrosis of the jaw: Results by real-time and wound healing in vitro assays

OBJECTIVE

This study investigated the effects of bisphosphonates and denosumab on human gingival fibroblasts (HGFs) that could influence inflammation, wound healing, and angiogenesis in medication-related osteonecrosis of the jaw (MRONJ).

METHODS

A real-time in vitro assay was performed on HGFs with and without the addition of bacterial lipopolysaccharide and a mononuclear cell co-culture to observe the effects of zoledronate, ibandronate, alendronate, clodronate, denosumab, and combinations of zoledronate and denosumab at varied concentrations. A wound healing assay was performed, and gene and protein expression was analyzed for inflammatory, angiogenic, and osteoclastogenic cytokines and mediators including interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNFα), IL-8, vascular endothelial growth factor (VEGF), RANKL, and osteoprotegerin.

RESULTS

Higher concentrations of antiresorptives resulted in impaired wound healing and HGF death, which also occurred without mechanical damage. These effects were increased with bacterial lipopolysaccharide and mononuclear cells. Increased levels of IL-1β, TNFα, IL-8, VEGF, osteoprotegerin, and decreased levels of IL-6 were observed.

CONCLUSIONS

Antiresorptive exposure was associated with HGF death and delayed wound healing, which could be attributed to an elevated inflammatory response and immune dysfunction contributing to MRONJ development. There was no evidence of anti-angiogenic effects. Our experiments present the first results of denosumab with HGFs.

Fatal Bleeding in Conjunction with Mandibular Medication-related Osteonecrosis of the Jaw (MRONJ)

Here, we report a case of fatal bleeding in conjunction with mandibular medicationrelated osteonecrosis of the jaw (MRONJ). A 75-year-old Japanese man was referred to our department with osteonecrosis of the jaw due to bisphosphonate (BP) for multiple bone metastases from prostate cancer. Aggressive surgical intervention was ruled out due to a poor prognosis in terms of life expectancy. Death occurred due to hemorrhagic shock resulting from massive oral bleeding caused by necrosis of the mandible. Numerous reports have suggested that jaw necrosis is induced not only by BP, but also RANKL antibody, steroids, and molecularly-targeted agents. This suggests that the number of cases of MRONJ is likely to increase among elderly patients in whom general health is already poor. The American Association of Oral and Maxillofacial Surgery recommends aggressive treatment only in cases of stage 3 disease. Therefore, such a therapeutic strategy may only be available for cases of jaw necrosis in which the general health status of the patient is otherwise good. To prevent a life-threatening outcome in cases of MRONJ, physicians, who are responsible for determining the drug strategy, should cooperate with oral surgeons in determining the best therapeutic strategy.

Current Understanding of the Pathophysiology of Osteonecrosis of the Jaw

PURPOSE OF REVIEW

Osteonecrosis of the jaw (ONJ) is a rare and severe necrotic bone disease reflecting a compromise in the body's osseous healing mechanisms and unique to the craniofacial region. Antiresorptive and antiangiogenic medications have been suggested to be associated with the occurrence of ONJ; yet, the pathophysiology of this disease has not been fully elucidated. This article raises the current theories underlying the pathophysiology of ONJ.

RECENT FINDINGS

The proposed mechanisms highlight the unique localization of ONJ. The evidence-based mechanisms of ONJ pathogenesis include disturbed bone remodeling, inflammation or infection, altered immunity, soft tissue toxicity, and angiogenesis inhibition. The role of dental infections and the oral microbiome is central to ONJ, and systemic conditions such as rheumatoid arthritis and diabetes mellitus contribute through their impact on immune resiliency. Current experimental studies on mechanisms of ONJ are summarized. The definitive pathophysiology is as yet unclear. Recent studies are beginning to clarify the relative importance of the proposed mechanisms. A better understanding of osteoimmunology and the relationship of angiogenesis to the development of ONJ is needed along with detailed studies of the impact of drug holidays on the clinical condition of ONJ.

Comparison of the histopathological characteristics of osteomyelitis, medication-related osteonecrosis of the jaw, and osteoradionecrosis

The purpose of this study was to compare the histopathological parameters of chronic/suppurative osteomyelitis, medication-related osteonecrosis of the jaw (MRONJ), and osteoradionecrosis (ORN), and to examine the hypothesis that distinct histological features can be related to a specific disease, allowing for diagnosis based on microscopic evaluation alone. One hundred and ten samples were reviewed by two examiners in a blinded fashion, and a semi-quantitative histomorphometric analysis was performed. The parameters evaluated included the presence or absence of necrotic bone, inflammation, reactive bone formation, bacteria, and osteoclasts. No statistically significant differences were found between groups for any parameter. Necrotic bone was common to all three diagnoses. Inflammation and reactive bone formation were present in all three diagnoses. The presence of bacteria was a prominent feature in all cases. Osteoclasts were scarce in MRONJ and osteomyelitis, and non-existent in ORN. The results of this study failed to identify distinctive microscopic characteristics in any of the three entities that could be used to differentiate between them. Therefore, it is impossible to reach a specific final diagnosis based on microscopic findings alone. The role of microscopic analysis is to serve as an aid to diagnosis that must be complemented by the patient's history and imaging.

Development of Antiresorptive Agent-Related Osteonecrosis of the Jaw After Dental Implant Removal: A Case Report

Dental implant treatment is a highly predictable therapy, but when potentially lethal symptoms or complications occur, dentists must remove the implant fixture. Recently, reports on antiresorptive agent-related osteonecrosis of the jaw have increased in the field of dental implants, although the relationship between dental implant treatment and antiresorptive agents remains unclear. Here, we report a case of antiresorptive agent-related osteonecrosis of the jaw that developed after dental implant removal. A 67-year-old Japanese woman with a medical history of osteoporosis and 7 years of oral bisphosphonate treatment was referred to our hospital with a chief complaint of painful right mandibular bone exposure. A family dentist removed the dental implants from the right mandible using a trephine drill without flap elevation in August 2016. However, the healing was impaired; she was referred to our hospital 3 months after the procedure. We performed a sequestrectomy of the mandible under general anesthesia. In conclusion, this patient's course has two important implications: First, the removal of dental implants from patients who are prescribed oral bisphosphonates for long durations can cause antiresorptive agent-related osteonecrosis of the jaw. Second, meticulous procedures are required to prevent and treat the development of antiresorptive agent-related osteonecrosis of the jaw after dental implant removal.

Microbial population changes in patients with medication-related osteonecrosis of the jaw treated with systemic antibiotics

OBJECTIVE

This study aimed to investigate the bacterial population in patients with medication-related osteonecrosis of the jaw (MRONJ) after treatment with doxycycline and metronidazole.

STUDY DESIGN

A total of 38 patients with MRONJ (age range 55-88, mean age 73 + 8.82 standard deviation) treated with doxycycline first and with metronidazole second were enrolled in this study. Two swabs were taken at the margin of the infected MRONJ lesion after applying pressure on the marginal mucosa, and visible pus was secreted. Real-time polymerase chain reaction was used to analyze 20 periopathogenic and commensal species and the total bacterial level. Bacterial counts were compared between antibiotic treatments and with a control group of orally healthy patients who didn't have periodontal pockets of more than 3 mm (n = 29) by means of a Mann-Whitney U test. Comparisons between the two antibiotic treatments were performed by a paired Wilcoxon signed rank test.

RESULTS

The total bacterial level was significantly higher in the MRONJ patients treated with systemic antibiotics compared with the control group. However, significant lower bacterial amounts were found for 12 of the 20 investigated bacteria. We couldn't establish a significant advantage of metronidazole administration after doxycycline treatment.

CONCLUSION

Our findings suggest that the total bacterial level in MRONJ patients is higher even when treated with systemic antibiotics. The significantly different bacterial amounts of the selected species suggest an alteration in the microbial population.

In Vitro Investigation of the Antimicrobial Effect of Three Bisphosphonates Against Different Bacterial Strains

PURPOSE

Since the first descriptions of medication-related osteonecrosis of the jaw (MRONJ) in 2003, the pathogenesis has remained unanswered. Recent histomorphometric studies have found several microorganisms, including Actinomyces, Bacillus, Fusobacterium, Staphylococcus, Streptococcus, Selenomonas, Treponema, and Candida albicans in necrotic bone. Polymerase chain reaction studies have recently confirmed the occurrence of 48 genera. Only a few studies have examined the antimicrobial effect of bisphosphonates (BPs). The influence of bacterial growth on the etiology remains unclear. The aim of the present study was the in vitro investigation of the antimicrobial effect of 3 BPs against different bacterial strains.

MATERIALS AND METHODS

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 48 strains from 40 species were determined in microdilution assays against pamidronic, ibandronic, and zoledronic acid.

RESULTS

Growth of gram-positive oral microbiota, which account for most microorganisms in MRONJ, was present for 2 of 22 species; 6 of 26 gram-negative species and 9 of 13 anaerobes were inhibited. The MIC values were compared with the BP bone concentrations from previous reports. Of the 48 strains, 9 had an MIC or MBC less than the bone concentrations.

CONCLUSIONS

The results of the present study have demonstrated that BPs have an inhibitory effect on selected bacterial species and might inhibit the growth of some relevant pathogens in osteonecrosis. However, most of the species tested were unaffected at the concentration levels assumed present in the human jawbone. The clinical relevance of these in vitro data will better be clarified with reliable data on the BP concentrations in the human jawbone. The present study has provided a first approach toward the assessment of the interaction of oral bacteria and BPs.

Osteonecrosis

Younger patients are affected more often by osteonecrosis than by osteoarthritis, and osteonecrosis has significantly greater long-term morbidity.

Corticosteroids are the most common cause of nontraumatic osteonecrosis.

The femoral head is the most common site of osteonecrosis.

In rare instances, osteonecrosis of the jaw has been associated with bisphosphonate exposure. This phenomenon is more common with repeated intravenous infusions of bisphosphonates.

Case reports of osteonecrosis of the jaw in association with other medications, such as denosumab, have been reported.

The final common pathway in the pathogenesis of osteonecrosis is disruption of blood supply to a segment of bone.

Abnormalities in lipid metabolism, bone homeostasis, regulation of apoptosis, coagulopathies, innate immunity, and oxidative stress may play a role in the pathogenesis of osteonecrosis.

Epigenetics may alter the predisposition to develop osteonecrosis.

MRI is currently the optimal test for early diagnosis and identification of the extent of osteonecrosis.

Nonsurgical treatment of osteonecrosis does not change the natural history of the disease.

Although surgical treatment of femoral head osteonecrosis has many variations, most symptomatic patients eventually require total hip arthroplasty.

Knowledge of risk factors and early detection are crucial to the successful management of osteonecrosis.

Because of the lack of successful treatment options, new modes of management focus on the prevention of osteonecrosis.

Microscopic Evaluation of the Effect of Oral Microbiota on the Development of Bisphosphonate-Related Osteonecrosis of the Jaws in Rats

Objectives

Osteonecrosis of the jaws is a side effect associated with the use of bisphosphonates. Using histologic analysis, this study aimed to evaluate the influence of microbial colonies in the development of osteonecrosis in the jaws of rats subjected to nitrogenous and non-nitrogenous bisphosphonates, undergoing surgical procedures.

Material and Methods

Thirty-four rats (Rattus norvegicus, Wistar strain) were allocated randomly into three groups: 12 animals treated with zoledronic acid; 12 animals treated with clodronate; and 10 animals treated with saline. Sixty days after the start of treatment, the animals underwent three extractions of the upper right molars. After 120 days of drug administration, the rats were killed. Histologic analysis was performed on specimens stained with hematoxylin and eosin by the technique of manual counting points using Image-Pro Plus software on images of the right hemimaxilla.

Results

Osteonecrosis was induced in the test groups. There was no statistically significant association between the presence of microbial colonies and the presence of non-vital bone (Kruskal-Wallis, P > 0.05).

Conclusions

Use of zoledronic acid was associated with non-vital bone and the results suggested that the presence of microbial colonies does not lead to osteonecrosis.

Bacterial diversity in medication-related osteonecrosis of the jaw

OBJECTIVE

The aim was to study the association between microflora and medication-related osteonecrosis of the jaw (MRONJ) by using culture-independent molecular techniques to detect bacteria in necrotic bone lesions.

STUDY DESIGN

Included were 18 consecutive patients with MRONJ, 10 with osteoporosis and 8 cancer patients. Bone biopsies were retrieved from the center of the necrotic bone and from visually healthy bone, and 16 S rRNA gene fragments from bacterial DNA were amplified with polymerase chain reaction.

RESULTS

The study revealed a diversity of bacteria represented by 16 S rRNA sequences in all the necrotic bone samples and in 60% of the visually healthy bone. Eight dominating taxa groups were identified at the genus level: Porphyromonas, Lactobacillus, Tannerella, Prevotella, Actinomyces, Treponema, Streptococcus, and Fusobacterium.

CONCLUSIONS

The necrotic bone lesions contained mainly anaerobic bacteria, representative of periodontal microflora, suggesting that a periodontal infection in combination with antiresorptive treatment could initiate osteonecrosis.

Treatment of medication-related osteonecrosis of the jaws (MRONJ) with ultrasonic piezoelectric bone surgery. A case series of 20 treated sites

PURPOSE

There is no consensus on how to successfully treat medication-related osteonecrosis of the jaws (MRONJ). We report here on the application of piezoelectric bone surgery to treat MRONJ in combination with antibiotherapy and on its possible benefit.

MATERIEL AND METHODS

A cohort of 18 consecutive patients has been treated for MRONJ; they involved 20 sites, 15 in the mandible, and five in the maxilla. Surgical removal of the necrotic areas and debridement was performed with a powerful piezoelectric surgery device (max 90 W) in combination with antibiotherapy.

RESULTS

All patients healed and obtained a complete soft tissue closure within 1 month. No recurrence of the symptoms was observed during the present follow-up (10-54 months).

CONCLUSION

We hypothesize that healing of all treated sites might have resulted from the synergic effect of bone ablation, biofilm alteration, and antibiotic administration. Biofilm alteration might have permitted a better access of antibiotics to the involved germs. These encouraging results warrant further studies on the use of ultrasonic surgery to treat MRONJ patients in order to confirm or refute the hypothesized effect.

Is GERD a Factor in Osteonecrosis of the Jaw? Evidence of Pathology Linked to G6PD Deficiency and Sulfomucins

Osteonecrosis of the jaw (ONJ), a rare side effect of bisphosphonate therapy, is a debilitating disorder with a poorly understood etiology. FDA's Adverse Event Reporting System (FAERS) provides the opportunity to investigate this disease. Our goals were to analyze FAERS data to discover possible relationships between ONJ and specific conditions and drugs and then to consult the scientific literature to deduce biological explanations. Our methodology revealed a very strong association between gastroesophageal reflux and bisphosphonate-induced ONJ, suggesting acidosis as a key factor. Overgrowth of acidophilic species, particularly Streptococcus mutans, in the oral microbiome in the context of insufficient acid buffering due to impaired salivary glands maintains the low pH that sustains damage to the mucosa. Significant associations between ONJ and adrenal insufficiency, vitamin C deficiency, and Sjögren's syndrome were found. Glucose 6 phosphate dehydrogenase (G6PD) deficiency can explain much of the pathology. An inability to maintain vitamin C and other antioxidants in the reduced form leads to vascular oxidative damage and impaired adrenal function. Thus, pathogen-induced acidosis, hypoxia, and insufficient antioxidant defenses together induce ONJ. G6PD deficiency and adrenal insufficiency are underlying factors. Impaired supply of adrenal-derived sulfated sterols such as DHEA sulfate may drive the disease process.