Bisphosphonates, vitamin D, parathyroid hormone, and osteonecrosis of the jaw. Could there be a missing link?

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.

The effect of vitamin D deficiency on the RANKL/OPG ratio in rats

The aim of this study was to determine the effect of vitamin D deficiency on the RANKL/OPG ((Receptor Activator of Nuclear Factor Kappa B Ligand/Osteoprotegerin) ratio in the serum blood levels. Sixteen Wistar rats were divided into 2 groups: a control group (C) and an experimental group (E). The group C comprised of rats with average vitamin D levels, while vitamin D deficiency was induced in those of group E. A test period of 21 days was employed wherein two serum blood samples were obtained, at the baseline (day 0) and at day 21. Changes in RANKL andOPG levels were measured using Enzyme-linked immunosorbent assay (ELISA) kits. A statistically significant decrease of serum RANKL concentration and RANKL/OPG ratio on day 21 was seen in the experimental group compared to the control group. The serum RANKL levels and RANKL/OPG ratio in rats, were negatively affected by the deficiency of vitamin D.

Effect of Human Umbilical Cord Matrix-Derived Mesenchymal Stem Cells on Bisphosphonate-Related Osteonecrosis of the Jaw

BACKGROUND

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a severe sequela caused by bisphosphonates (BPs), which are widely used to treat osteoporosis or other malignancies. However, the mechanism underlying BRONJ remains unclear. Recently, human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have been studied for treatment of diverse diseases and injuries. This study aimed to investigate the therapeutic effects of hUC-MSCs in BRONJ.

METHODS

The therapeutic effects of hUC-MSCs were examined in rat bone marrow (rBM)-derived cells using cell viability, colony-forming, and real-time PCR assays and FACS for analyzing essential proinflammatory and bone regeneration markers in vitro. To demonstrate the in vivo therapeutic and adverse effects of transfused hUC-MSCs, micro-CT, H&E staining, IHC (Angiogenesis marker gene expression) staining, and parathyroid hormone (PTH)/calcium assay were conducted in a BRONJ-induced animal model.

RESULTS

BP-induced cytotoxicity and inflammation in rBM-derived cells decreased, after co-culture with hUC-MSCs. The expression levels of bone regeneration markers (RUNX2, OSX, and BMP-2) significantly increased in BP-treated rBM-derived cells, after co-culture with hUC-MSCs. The BP-induced abnormal shift in RANKL/OPG expression ratio in rBM-derived cells was normalized by hUC-MSCs. Consistent with these in vitro results, transfused hUC-MSCs markedly decreased BRONJ and significantly healed injured mucosa in the BRONJ-induced animal model. The animals exhibited serious destruction of the kidney structure and increases in serum PTH and calcium levels, which were significantly normalized by hUC-MSC transfusion.

CONCLUSION

hUC-MSCs exerted therapeutic effects on BRONJ in vitro and in vivo through their anti-cytotoxicity, anti-inflammatory activity and ability to recover bone regeneration.

Medication-related osteonecrosis of the jaw associated with implant and regenerative treatments: Systematic review

BACKGROUND

The aim of this study was to determine if the treatment with bisphosphonates other anti-resorptive and antiangiogenic agents influences the success of regenerative and / or implant treatments.

MATERIAL AND METHODS

We reviewed the literature from the last 5 years in the PubMed database, using the following words: "Sinus Floor Augmentation"[Mesh] OR "Dental Implants"[Mesh]) OR "Guided Tissue Regeneration"[Mesh]) AND "Osteonecrosis"[Mesh]. The articles were selected following the inclusion and exclusion criteria and were evaluated using the 22 items of the STROBE declaration. The following PICO clinical question was applied: Does the treatment with agents associated with drug osteonecrosis influence the success of regenerative and implant treatments?

RESULTS

The initial search resulted in a total of 27 articles. After eliminating those that did not refer to the topic, were duplicated or did not meet the inclusion / exclusion criteria, a full reading of the articles was made evaluating their methodological quality, obtaining six studies with high methodological quality and two with moderate.

CONCLUSIONS

The literature regarding this topic is scarce, randomized clinical trials would be necessary to establish protocols relative to implant treatment in patients on antiresorptive treatments. The risk of developing an osteonecrosis associated with the regeneration / implant placement in patients with benign bone diseases is scarce, but it exists and it should not be underestimated. Especially, in the posterior areas of the jaw, if the duration of treatment with BP is greater than 3 years, and if the patient is under therapy with systemic corticosteroids.

Steroid phosphate esters and phosphonosteroids and their biological activities

Steroid phosphate esters are very rare natural lipids that have been comparatively recently isolated from fractions of polar lipids of marine sponges and starfish. These steroids exhibit interesting biological activities. When using the PASS computer program, we showed that many of steroid phosphate esters showed antifungal, antihypercholesterolemic, anesthetic, and other activities with a confidence of 73 to 93%. In addition, some of them can be used as inhibitors of cholesterol synthesis and show hepatoprotection properties. Phosphonosteroids demonstrate antineoplastic and antihypercholesterolemic activities with a certainty of 85 to 90%. And also, they can be used as ovulation inhibitors or female steroid contraceptives with confidence from 86 to 98%.

Analysis of different therapeutic protocols for osteonecrosis of the jaw associated with oral and intravenous bisphosphonates

Introduction

Chemotherapy-associated osteonecrosis of the jaw caused by bisphosphonates is an exposure of necrotic bone with more than eight weeks of evolution that is attributable to bisphosphonates and no prior radiation therapy. Its etiopathogenesis remains unknown, although there are two hypotheses that may explain it: the drug’s mechanism of action, and the risk factors that can lead to osteonecrosis. There is a wide range of treatment options for managing chemotherapy-associated osteonecrosis of the jaw, from conservative treatments to surgical procedures of varying levels of invasiveness, which are sometimes supplemented with adjuvant therapies.

Objectives

The objective of this article is to group the therapeutic options for osteonecrosis of the jaw (ONJ) into seven different protocols and to evaluate their effectiveness in relation to stage of ONJ.

Material and Methods

A literature review was carried out in PubMed following the PRISMA criteria. A total of 47 were collected after compiling a series of variables that define ONJ, applied treatments, and the clinical results obtained.

Results and Discussion

The 47 articles selected have a low to average estimated risk of bias and are of moderate to good quality. According to the data obtained, Protocol 3 (conservative treatment, clinical and radiological follow-up, minimally invasive surgical treatment, and adjuvant therapies) is the most favorable approach for ONJ lesions caused by oral bisphosphonates. For lesions caused by intravenous bisphosphonates, Protocol 2 (conservative treatment, clinical and radiological follow-up, minimally invasive surgical treatment, and no adjuvant therapies) is the best approach. When comparing the different stages of ONJ, Protocol 1 (conservative treatment, clinical and radiological follow-up) promotes better healing of Stage 1 ONJ lesions caused by orally administered bisphosphonates, and Protocol 3 is recommended for Stage II. For ONJ lesions attributable to intravenous bisphosphonates, Protocol 7 (conservative treatment, clinical and radiological follow-up, and adjuvant therapies) provides the best results in Stage 0; in Stages I, II, and III, Protocol 1 gives better results.

Key words:Bisphosphonates, bronj, therapeutic protocol, clinical result.

Prophylaxis and antibiotic therapy in management protocols of patients treated with oral and intravenous bisphosphonates

INTRODUCTION

Osteonecrosis of the jaw (MRONJ) linked to bisphosphonate treatment has specific characteristics that render its therapeutic management challenging for clinicians. Poor response to standard treatment makes it essential to take special precautions when treating this type of disease; therefore, antibiotic prophylaxis and/or antibiotic therapy have been proposed as effective and helpful tools in these situations.

OBJECTIVES

This article seeks to assess published evidence in order to evaluate the different protocols used for antibiotic prophylaxis and/or antibiotic therapy in the general context of patients treated with bisphosphonates.

MATERIAL AND METHODS

A literature review of the last 10 years was carried out in PubMed using the following keywords: "antibiotic prophylaxis and osteonecrosis," "bisphosphonates AND osteonecrosis AND dental management," "bisphosphonate AND osteonecrosis AND antibiotic prophylaxis AND oral surgery." A total of 188 articles were obtained, of which 18 were ultimately selected.

RESULTS AND DISCUSSION

In patients treated with oral and intravenous bisphosphonates without chemotherapy-associated osteonecrosis of the jaw, antibiotic prophylaxis prior to oral surgery is an important tool to avoid osteonecrosis and promote healing of the affected area. If the patient previously exhibited chemotherapy-associated osteonecrosis after tooth extraction, antibiotic prophylaxis is indicated to prevent recurrent osteonecrosis and promote healing of the extraction site. If chemotherapy-associated osteonecrosis is already present, antibiotic therapy is a vital part of conservative management to reduce the symptomatology of MRONJ and keep it from worsening. Finally, a lack of clinical data and randomized controlled trials makes it difficult to choose the most appropriate protocol for the various clinical situations studied. Key words:Bisphosphonates, antibiotic prophylaxis, maxillary osteonecrosis, antibiotic treatment.

Hyperbaric oxygen therapy and osteonecrosis

Osteonecrosis of the jaw may be caused by radiation, medication, or infection. Optimal therapy requires a multimodal approach that combines surgery with adjuvant treatments. This review focuses on the use of adjunctive hyperbaric oxygen therapy for this condition. In addition to evidence regarding the basic and clinical science behind hyperbaric oxygen therapy, controversies in the field and economic implications are discussed.