Osteomalacia: the missing link in the pathogenesis of bisphosphonate-related osteonecrosis of the jaws?

Italian position paper (SIPMO-SICMF) on medication-related osteonecrosis of the jaw (MRONJ)

OBJECTIVE

This paper aims to describe the 2023 update position paper on MRONJ developed by the Italian Societies of Oral Pathology and Medicine (SIPMO) and of Maxillofacial Surgery (SICMF).

METHODS

This is the second update following the 2013 and 2020 Italian position papers by the Expert panel, which is a representation of the two scientific societies (SIPMO and SICMF). The paper is based on an extensive analysis of the available literature from January 2003 to February 2020, and the subsequent review of literature conducted between March 2020 and December 2022 to include all new relevant published papers to confirm or modify the previous set of recommendations.

RESULTS

This position paper highlights the main issues of MRONJ on risk estimates, disease definition, diagnostic pathway, individual risk assessment, and the fundamental role of imaging in the diagnosis, classification, and management of MRONJ.

CONCLUSION

The Expert Panel confirmed the MRONJ definition, the diagnostic work-up, the clinical-radiological staging system and the prophylactic drug holiday, as recognized by SIPMO-SICMF; while, it presented novel indications regarding the categories at risk of MRONJ, the prevention strategies, and the treatment strategies associated with the therapeutic drug holiday.

Molecular Quantity Variations in Human-Mandibular-Bone Osteoid

Osteoid is a layer of new-formed bone that is deposited on the bone border during the process of new bone formation. This deposition process is crucial for bone tissue, and flaws in it can lead to bone diseases. Certain bone diseases, i.e. medication related osteonecrosis, are overexpressed in mandibular bone. Because mandibular bone presents different properties than other bone types, the data concerning osteoid formation in other bones are inapplicable for human-mandibular bone. Previously, the molecular distribution of other bone types has been presented using Fourier-transform infrared (FTIR) spectroscopy. However, the spatial distribution of molecular components of healthy-human-mandibular-bone osteoid in relation to histologic landmarks has not been previously presented and needs to be studied in order to understand diseases that occur human-mandibular bone. This study presents for the first time the variation in molecular distribution inside healthy-human-mandibular-bone osteoid by juxtaposing FTIR data with its corresponding histologic image obtained by autofluorescence imaging of its same bone section. During new bone formation, bone-forming cells produce an osteoid constituted primarily of type I collagen. It was observed that in mandibular bone, the collagen type I increases from the osteoblast line with the distance from the osteoblasts, indicating progressive accumulation of collagen during osteoid formation. Only later inside the collagen matrix, the osteoid starts to mineralize. When the mineralization starts, the collagen accumulation diminishes whereas the collagen maturation still continues. This chemical-apposition process in healthy mandibular bone will be used in future as a reference to understand different pathologic conditions that occur in human-mandibular bone.

Interest of Bone Histomorphometry in Bone Pathophysiology Investigation: Foundation, Present, and Future

Despite the development of non-invasive methods, bone histomorphometry remains the only method to analyze bone at the tissue and cell levels. Quantitative analysis of transiliac bone sections requires strict methodologic conditions but since its foundation more 60 years ago, this methodology has progressed. Our purpose was to review the evolution of bone histomorphometry over the years and its contribution to the knowledge of bone tissue metabolism under normal and pathological conditions and the understanding of the action mechanisms of therapeutic drugs in humans. The two main applications of bone histomorphometry are the diagnosis of bone diseases and research. It is warranted for the diagnosis of mineralization defects as in osteomalacia, of other causes of osteoporosis as bone mastocytosis, or the classification of renal osteodystrophy. Bone biopsies are required in clinical trials to evaluate the safety and mechanism of action of new therapeutic agents and were applied to anti-osteoporotic agents such as bisphosphonates and denosumab, an anti-RANKL, which induces a marked reduction of the bone turnover with a consequent elongation of the mineralization period. In contrast, an increased bone turnover with an extension of the formation site is observed with teriparatide. Romosozumab, an anti-sclerostin, has a dual effect with an early increased formation and reduced resorption. Bone histomorphometric studies allow us to understand the mechanism of coupling between formation and resorption and to evaluate the respective role of bone modeling and remodeling. The adaptation of new image analysis techniques will help bone biopsy analysis in the future.

Time for Revival of Bone Biopsy with Histomorphometric Analysis in Chronic Kidney Disease (CKD): Moving from Skepticism to Pragmatism

Bone Biopsy (BB) with histomorphometric analysis still represents the gold standard for the diagnosis and classification of different forms of renal osteodystrophy. Bone biopsy is the only technique able to provide comprehensive information on all bone parameters, measuring static and dynamic parameters of turnover, cortical and trabecular microarchitecture, and mineralization defects. In nephrological practice, bone biopsy yields relevant indications to support therapeutic choices in CKD, heavily impacting the management and prognosis of uremic patients. Unfortunately, the use of bone biopsy has decreased; a lack of expertise in performing and interpreting, perceived procedure invasiveness and pain, and reimbursement issues have all contributed to this decline. Nevertheless, both bone biomarkers and instrumental images cannot be considered reliable surrogates for histological findings, being insufficiently accurate to properly evaluate underlying mineral and bone disorders. This is a multidisciplinary position paper from the Nephrology and Osteoporosis Italian Scientific Societies with the purpose of restating the role of bone biopsy in CKD patient management and of providing strong solutions to allow diffusion of this technique in Italy, but potentially also in other countries. The Italian approach through the optimization and standardization of bone biopsy procedure, the construction of the Italian Hub and Spoke network, and a request for adjustment and national homogenization of reimbursement to the Italian Health Ministry has led the way to implement bone biopsy and to improve CKD patient management and prognosis.

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.

Early Changes of VEGF Levels After Zoledronic Acid in Women With Postmenopausal Osteoporosis: A Potential Role of Vitamin D

Zoledronic acid (Zol) is a widely used intravenous aminobisphosphonate to treat both benign and malignant skeletal diseases, and bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious side effect whose pathophysiology remains poorly understood. Vascular Endothelial Growth Factor (VEGF) has been recognized to mediate BRONJ in cancer patients undergoing Zol treatment, however data on VEGF are lacking in patients with osteoporosis. Increasing evidences demonstrate that vitamin D influences VEGF levels. The aim of this study was to investigate the influence of Zol on VEGF levels and the possible role for vitamin D on the Zol mediated changes of VEGF concentration in women with postmenopausal osteoporosis. Twenty-eight postmenopausal women with osteoporosis were enrolled and randomized into two groups to receive Zol (5 mg) or placebo. At baseline, at day-3 and day-30 VEGF serum levels were measured; bone turnover markers, 25-hydroxyvitamin D [25(OH)D] and serum calcium were evaluated at baseline. In Zol-treated women, VEGF increased significantly on day-3, and then decreased on day-30. In the Zol-treated women, the percent change of VEGF levels between baseline and day-30 (-18% at day-30 vs. baseline, p = 0.01) was significantly associated with serum 25(OH)D values (r = 0.29, p = 0.028). At a stepwise multiple regression analysis, after correcting for age, BMI, time since menopause, femoral neck BMD, osteocalcin, C-terminal telopeptide of type 1 collagen, and baseline VEGF levels, 25(OH)D levels were independently associated with VEGF change (β = 1.7, SE = 0.71, p = 0.03). For the first time, we detected early modifications of circulating VEGF in postmenopausal women receiving Zol for osteoporosis, identifying a vitamin D-dependent modulation of these changes.

Bone Biopsy for Histomorphometry in Chronic Kidney Disease (CKD): State-of-the-Art and New Perspectives

The use of bone biopsy for histomorphometric analysis is a quantitative histological examination aimed at obtaining quantitative information on bone remodeling, structure and microarchitecture. The labeling with tetracycline before the procedure also allows for a dynamic analysis of the osteoblastic activity and mineralization process. In the nephrological setting, bone biopsy is indicated to confirm the diagnosis of subclinical or focal osteomalacia and to characterize the different forms of renal osteodystrophy (ROD). Even if bone biopsy is the gold standard for the diagnosis and specific classification of ROD, the use of this approach is very limited. The main reasons for this are the lack of widespread expertise in performing or interpreting bone biopsy results and the cost, invasiveness and potential pain associated with the procedure. In this regard, the sedation, in addition to local anesthesia routinely applied in Italian protocol, significantly reduces pain and ameliorates the pain perception of patients. Concerning the lack of widespread expertise, in Italy a Hub/Spokes model is proposed to standardize the analyses, optimizing the approach to CKD patients and reducing the costs of the procedure. In addition, new tools offer the possibility to evaluate the osteogenic potential or the ability to form bone under normal and pathological conditions, analyzing mesenchymal stem cells and their ability to differentiate in the osteogenic lineage. In the same way, circulating microRNAs are suggested as a tool for exploring osteogenic potential. The combination of different diagnostic approaches and the optimization of the bioptic procedure represent a concrete solution to spread the use of bone biopsy and optimize CKD patient management.

Medication-Related Osteonecrosis of the Jaw (MRONJ): Are Antiresorptive Drugs the Main Culprits or Only Accomplices? The Triggering Role of Vitamin D Deficiency

Osteonecrosis of the jaw (ONJ) is a severe clinical condition characterized mostly but not exclusively by an area of exposed bone in the mandible and/or maxilla that typically does not heal over a period of 6-8 weeks. The diagnosis is first of all clinical, but an imaging feedback such as Magnetic Resonance is essential to confirm clinical suspicions. In the last few decades, medication-related osteonecrosis of the jaw (MRONJ) has been widely discussed. From the first case reported in 2003, many case series and reviews have appeared in the scientific literature. Almost all papers concerning this topic conclude that bisphosphonates (BPs) can induce this severe clinical condition, particularly in cancer patients. Nevertheless, the exact mechanism by which amino-BPs would be responsible for ONJ is still debatable. Recent findings suggest a possible alternative explanation for BPs role in this pattern. In the present work we discuss how a condition of osteomalacia and low vitamin D levels might be determinant factors.

Bisphophonate alterations of the jaw bones in individuals with multiple myeloma

OBJECTIVES

To verify quantitative differences of the mandibular cortical and trabecular bone between patients with multiple myeloma (MM) under bisphosphonate (BP) therapy and a control group never exposed to BP.

METHODS

Clinical and demographic characteristics were collected through medical records and interviews. Mandibular cortical thickness (MCT) and fractal dimension (FD) were measured on cone beam computed tomography (CBCT) images, on the molar region, in both groups. Additionally, FD was measured on periapical digital intraoral radiography and results were compared to CBCT measurements.

RESULTS

There were 33 patients with MM under BP therapy and 28 controls, with no significant differences in gender and age between groups. Pamidronate was used by all MM patients, either associated or not to other types of BP. The median MCT was higher in MM group exposed to BP (5.20 mm) than in controls (3.50 mm, p < 0.001). There were no significant differences in the median FD between patients in the MM group and controls, on CBCT (0.95 vs 0.90, p = 0.814) and periapical digital intraoral radiography (0.98 vs 0.96, p = 0.963), respectively, even when more than one type of BP was used.

CONCLUSIONS

The MCT represents an useful tool in the detection of bone dimensional changes caused by BP, in patients with MM. Additional studies are necessary to improve the knowledge on the quantitative evaluation of trabecular jaw bone, in individuals with MM, under BP therapy.

From Osteoclast Differentiation to Osteonecrosis of the Jaw: Molecular and Clinical Insights

Bone physiology relies on the delicate balance between resorption and formation of its tissue. Bone resorption depends on a process called osteoclastogenesis in which bone-resorbing cells, i.e., osteoclasts, are produced by the differentiation of more undifferentiated progenitors and precursors. This process is governed by two main factors, monocyte-colony stimulating factor (M-CSF) and receptor activator of NFκB ligand (RANKL). While the former exerts a proliferating effect on progenitors/precursors, the latter triggers a differentiation effect on more mature cells of the same lineage. Bone homeostasis requires a perfect space–time coordination of the involved signals. When osteoclastogenesis is poorly balanced with the differentiation of the bone forming counterparts, i.e., osteoblasts, physiological bone remodelling can turn into a pathological state, causing the systematic disruption of bone tissue which results in osteopenia or osteolysis. Examples of these conditions are represented by osteoporosis, Paget’s disease, bone metastasis, and multiple myeloma. Therefore, drugs targeting osteoclastogenesis, such as bisphosphonates and an anti-RANKL monoclonal antibody, have been developed and are currently used in the treatment of such diseases. Despite their demonstrated therapeutic efficacy, these agents are unfortunately not devoid of side effects. In this regard, a condition called osteonecrosis of the jaw (ONJ) has been recently correlated with anti-resorptive therapy. In this review we will address the involvement of osteoclasts and osteoclast-related factors in the pathogenesis of ONJ. It is to be hoped that a better understanding of the biological mechanisms underlying bone remodelling will help in the design a medical therapeutic approach for ONJ as an alternative to surgical procedures.

Man of Steel Syndrome: Silicone and Mineral Oil Injections With Associated Hypercalcemia, Hypophosphatemia, and Proximal Muscle Weakness

Silicone/mineral oil‐induced granulomas have been described as an inflammatory granulomatous response when silicone/mineral oil is injected for cosmetic purposes. These sclerosing granulomas can lead to hypercalcemia. Here we present a 33‐year‐old man with hypercalcemia, hypophosphatemia, progressively worsening fatigue, severe proximal muscle weakness, and depression. He had an athletic build with increased muscle bulk and several areas of indurated, nontender, firm, well‐circumscribed lesions in the subcutaneous tissue of his anterior pectoralis, triceps, and biceps bilaterally because of injecting himself with silicone/mineral oil‐based product into his muscles. Sclerosing granulomas were diagnosed on the MRI. He had extremely low or undetectable serum levels of 25‐hydroxyvitamin D [25(OH)D], and persistently elevated serum levels of 1,25‐dihydroxyvitamin D [1,25(OH)₂D] and calcium. He developed hypophosphatemia associated with elevated levels of fibroblast growth factor 23 (FGF‐23) and severe proximal muscle weakness. Treatment with systemic steroids, furosemide, calcitonin, ketoconazole, and denosumab resulted in a significant decrease in his serum calcium, but with minimal impact on his hypophosphatemia and fatigue.Correcting his severe vitamin D deficiency with small doses of vitamin D and raising his blood level of 25(OH)D from undetectable to 10 ng/mL without significantly affecting his serum calcium or phosphate was effective in reversing his severe proximal muscle weakness, permitting him to lift his head and to be free of his wheelchair. Although measurement of the 1,25(OH)₂D level is not mandatory in all cases of hypercalcemia, it is indicated in a patient who has low serum PTH levels. Clinicians need to be aware that vitamin D deficiency can cause severe proximal muscle weakness such that the patient is unable to lift his head from his chest or ambulate. This may lead to a psychiatric disorder misdiagnosis. © 2019 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Is vitamin D deficiency a risk factor for osteonecrosis of the jaw in patients with cancer? A matched case-control study

PURPOSE

A previous case-control histomorphometric study showed higher odds of osteomalacia in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Vitamin D deficiency causes osteomalacia and may therefore be involved in the pathogenesis of BRONJ. The present case-control study aimed at testing such hypothesis.

MATERIALS AND METHODS

BRONJ+ and BRONJ- patients treated with bisphosphonates were matched by sex (same) and age (within 5 years). Serum 25-hydroxy-vitamin D (25-OH-D), parathyroid hormone, bone alkaline phosphatase, total procollagen type 1 amino-terminal propeptide, carboxy-terminal collagen crosslinks, Dickkopf WNT signaling pathway inhibitor 1 and sclerostin were measured.

RESULTS

The main outcome was vitamin D deficiency defined as 25-OH-D < 50 nmol/l. A total of 51 BRONJ+ and 73 BRONJ- patients were studied. The frequency (95% CI) of vitamin D deficiency was 59% (45%-72%) in BRONJ+ and 62% (48%-75%) in BRONJ- patients. This amounts to a difference of -3% (-22%-16%, p = 0.77) for BRONJ+ patients. Serum 25-hydroxy-vitamin D and parathyroid hormone were similar in BRONJ+ and BRONJ- patients. Among the bone metabolism markers, only sclerostin differed between the two groups, being higher in BRONJ+ patients.

CONCLUSION

The present matched case-control study suggests that vitamin D deficiency is not a risk factor for BRONJ.

Vitamin D supplementation: Hypothetical effect on medication-related osteonecrosis of the jaw

Vitamin D is an important nutrient for bone health and skeleton growth. Few foods are natural sources of this secosteroid; this is the reason why the consumption of vitamin D as a dietary supplement is becoming common in developed countries. For many years vitamin D has been considered crucial in the treatment and prevention of the Global Burden of Disease and in a reduction in mortality among elder people. Many health care providers prescribe these supplements in the management of osteoporosis and metabolic bone diseases; specifically in the primary prevention of fractures. Recently medication-related osteonecrosis of the jaw (MRONJ) has been reported as severe late sequelae of antiresorptive therapies (i.e., bisphosphonates and some monoclonal antibodies). Although MRONJ-related pathophysiology is not fully understood, there are three fundamental theories to explain it: (1) the inhibition of osteoclasts, (2) the inhibition of angiogenesis and (3) the processes of inflammation-infection. Recent advances in Vitamin D research have shown that this secosteroid can play a potential pivotal role in many of the different etiological pathways of MRONJ. Furthermore, there are a large number of co-morbidities between the deficit of this vitamin and other MRONJ concomitant outcomes. Our hypothesis argues that the low-risk and low-cost vitamin D dietary supplementation may prove to be suitable for use as a practical MRONJ prevention strategy. The described framework gives more insight into the study of disease mechanisms, search of potential biomarkers, and therapeutic targets in MRONJ.

Craniofacial Manifestations of Systemic Disorders: CT and MR Imaging Findings and Imaging Approach

Many systemic diseases or conditions can affect the maxillofacial bones; however, they are often overlooked or incidentally found at routine brain or head and neck imaging performed for other reasons. Early identification of some conditions may significantly affect patient care and alter outcomes. Early recognition of nonneoplastic hematologic disorders, such as thalassemia and sickle cell disease, may help initiate earlier treatment and prevent serious complications. The management of neoplastic diseases such as lymphoma, leukemia, or Langerhans cell histiocytosis may be different if diagnosed early, and metastases to the maxillofacial bones may be the first manifestation of an otherwise occult neoplasm. Endocrinologic and metabolic disorders also may manifest with maxillofacial conditions. Earlier recognition of osteoporosis may alter treatment and prevent complications such as insufficiency fractures, and identification of acromegaly may lead to surgical treatment if there is an underlying growth hormone-producing adenoma. Bone dysplasias sometimes are associated with skull base foraminal narrowing and subsequent involvement of the cranial nerves. Inflammatory processes such as rheumatoid arthritis and sarcoidosis may affect the maxillofacial bones, skull base, and temporomandibular joints. Radiologists should be familiar with the maxillofacial computed tomographic and magnetic resonance imaging findings of common systemic disorders because these may be the first manifestations of an otherwise unrevealed systemic process with potential for serious complications. Online supplemental material is available for this article. ^©RSNA, 2018.

Runx2 overexpression compromises bone quality in acromegalic patients

Acromegalic patients, characterized by excessive secretion of GH and IGF-1, show a high fracture risk but bone mineral density is a poor predictor for bone fractures in these patients. The effects of an excess of GH/IGF1 on skeleton as well as on osteogenic progenitors, i.e. mesenchymal stem cells, have not been investigated in these patients. We aimed to elucidate the skeletal conditions of acromegalic patients by means of bone microarchitecture analysis and evaluation of MSCs osteogenic commitment. In particular, we performed histomorphometric analyses, and we quantified the expression levels of the osteogenic transcription factor RUNX2 in circulating MSCs. Our results showed an abnormal microarchitecture and demonstrated that bone impairment in acromegalic patients is associated with the upregulation of RUNX2 expression. Furthermore, osteoblastic activity was significantly reduced in patients under pharmacological treatment, compared to untreated patients. In conclusion, this study demonstrates the key role of RUNX2 gene overexpression in causing bone impairment in acromegalic patients. It also suggests a therapeutic approach for the improvement of bone quality, focused on the osteoblastic lineage rather than the inhibition of osteoclastic activity.

Vitamin D (25-OHD) deficiency may increase the prevalence of medication-related osteonecrosis of the jaw

INTRODUCTION

Osteonecrosis of the jaw (ONJ) is a severe complication of antiresorptive medication (AM) in the treatment of bone-affecting cancer-related conditions and osteoporosis. Aim of this study was to reveal whether patients treated with AM and show Medication Related OsteoNecrosis of the Jaw (MRONJ) are vitamin D deficient or not.

MATERIALS AND METHODS

A 2 year retrospective study evaluated hospital records of 63 patients who received AM. Patients were divided into two groups. One group (n = 45) consisted of patients who presented a stage 2 ONJ (eb+ = exposed bone). Second group patients (n = 18) (eb- = no exposed bone) presented for extraction of teeth. Serum levels of vitamin D (25-OHD) were analysed. P values ≤ 0.05 in t-test were regarded as statistically significant.

RESULTS

Serum levels of 25-OHD were significantly higher in the eb(-) group (29.5 ng/ml), than in the eb(+) group (20.49 ng/ml). Blood levels of calcium were also significantly higher in eb(-) group (2.25 mmol/L; 0.11 SD) than in eb(+) group (2.175 mmol/L; 0.16 SD).

CONCLUSION

Prevalence of MRONJ in AM treated patients seems to be increased by low serum 25-OHD. A measurable tendency in the role of 25-OHD for the development of MRONJ was recorded and leads to the recommendation for a sufficient vitamin D substitution in patients treated with AM.

Micronutrients in Oncological Intervention

Nutritional supplements are widely used among patients with cancer who perceive them to be anticancer and antitoxicity agents. Depending on the type of malignancy and the gender 30%-90% of the cancer patients supplement their diets with antioxidant and immuno-stabilizing micronutrients, such as selenium, vitamin C, and vitamin D, often without the knowledge of the treating physician. From the oncological viewpoint, there are justifiable concerns that dietary supplements decrease the effectiveness of chemotherapy and radiotherapy. Recent studies, however, have provided increasing evidence that treatment is tolerated better-with an increase in patient compliance and a lower rate of treatment discontinuations-when micronutrients, such as selenium, are added as appropriate to the patient's medication. Nutritional supplementation tailored to an individual's background diet, genetics, tumor histology, and treatments may yield benefits in subsets of patients. Clinicians should have an open dialogue with patients about nutritional supplements. Supplement advice needs to be individualized and come from a credible source, and it is best communicated by the physician.

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

It is estimated that over 190 million bisphosphonates have been prescribed worldwide. But this drug can produce adverse effects, of which osteonecrosis of the jaw and severe hypocalcemia are the most serious. It is evident that bisphosphonate administration affects multiple and diverse biochemical mediators related to bone metabolism. This review of literature investigates four basic parameters in patients treated with bisphosphonates - parathyroid hormone (PTH), bisphosphonates, vitamin D, calcium, and jaw osteonecrosis - which are fundamental for assessing bone metabolism and so the efficacy and correct use of the drug. The imbalances generated by vitamin D and calcium deficiencies, together with their multiple systemic repercussions, have been widely researched but the outcomes of these imbalances in relation to bisphosphonate administration are not well known, and some research has indicated that they may be associated with osteonecrosis of the jaw (ONJ). The present review set out to explain the functioning of bone metabolism, the importance of different chemical mediators, the imbalances produced by incorrect use of this drug, in order to forewarn against the possible relation of these parameters with ONJ, whose physiopathology remains unknown. Medical and dental clinics should keep detailed anamneses of the use of vitamin D and calcium supplements, as it is of vital importance to maintain their correct levels in blood, given that these are related to ONJ as well as other adverse effects; this procedure is also necessary in order to ensure the correct use of the drug.

Key words:Bisphosphonate-related osteonecrosis of the jaw, vitamin D, parathyroid hor

The effect of nitrogen containing bisphosphonates, zoledronate and alendronate, on the production of pro-angiogenic factors by osteoblastic cells

Bisphosphonates (BPs) have been shown to influence angiogenesis. This may contribute to BP-associated side-effects such as osteonecrosis of the jaw (ONJ) or atypical femoral fractures (AFF). The effect of BPs on the production of angiogenic factors by osteoblasts is unclear. The aims were to investigate the effect of (1) alendronate on circulating angiogenic factors; vascular endothelial growth factor (VEGF) and angiopoietin-1 (ANG-1) in vivo and (2) zoledronate and alendronate on the production of VEGF and ANG-1 by osteoblasts in vitro. We studied 18 post-menopausal women with T score⩽-2 randomized to calcium/vitamin D only (control arm, n=8) or calcium/vitamin D and alendronate 70mg weekly (treatment arm, n=10). Circulating concentrations of VEGF and ANG-1 were measured at baseline, 3, 6 and 12months. Two human osteoblastic cell lines (MG-63 and HCC1) and a murine osteocytic cell line (MLO-Y4) were treated with zoledronate or alendronate at concentrations of 10(-12)-10(-6)M. VEGF and ANG-1 were measured in the cell culture supernatant. We observed a trend towards a decline in VEGF and ANG-1 at 6 and 12months following treatment with alendronate (p=0.08). Production of VEGF and ANG-1 by the MG-63 and HCC1 cells decreased significantly by 34-39% (p<0.01) following treatment with zoledronate (10(-9)-10(-6)M). Treatment of the MG-63 cells with alendronate (10(-7) and 10(-6)) led to a smaller decrease (25-28%) in VEGF (p<0.05). Zoledronate (10(-10)-10(-)(6)M) suppressed the production of ANG-1 by MG-63 cells with a decrease of 43-49% (p<0.01). Co-treatment with calcitriol (10(-8)M) partially reversed this zoledronate-induced inhibition. BPs suppress osteoblastic production of angiogenic factors. This may explain, in part, the pathogenesis of the BP-associated side-effects.

Epidemiology, clinical manifestations, risk reduction and treatment strategies of jaw osteonecrosis in cancer patients exposed to antiresorptive agents

ABSTRACT: Osteonecrosis of the jaws (ONJ) is an adverse side event of bisphosphonates and denosumab, antiresorptive agents that effectively reduce the incidence of skeletal-related events in patients with metastatic bone cancer and multiple myeloma. Available data suggest that 0–27.5% of individuals exposed to antiresorptive agents can develop ONJ. There is increasing evidence that avoidance of surgical trauma and infection to the jawbones can minimize the risk of ONJ, but there are still a significant number of individuals who develop ONJ in the absence of these risk factors. Bone necrosis is almost irreversible and there is no definitive cure for ONJ with the exclusion, in certain cases, of surgical resection. However, most ONJ individuals are affected by advanced incurable cancer and are often managed with minimally invasive nonsurgical interventions in order to control jawbone infections and painful symptoms. This article summarizes current knowledge of ONJ epidemiology, manifestations, risk-reduction and therapeutic strategies. Further research is needed in order to determine individual predisposition to ONJ and clarify the effectiveness of available treatments.

Vitamin D: Update 2013: From rickets prophylaxis to general preventive healthcare

Vitamin D has received a lot of attention recently as a result of a meteoric rise in the number of publications showing that vitamin D plays a crucial role in a plethora of physiological functions and associating vitamin D deficiency with many acute and chronic illnesses including disorders of calcium metabolism, autoimmune diseases, some cancers, type 2 diabetes mellitus, infectious diseases and cardiovascular disease. The recent data on vitamin D from experimental, ecological, case-control, retrospective and prospective observational studies, as well as smaller intervention studies, are significant and confirm the sunshine vitamin's essential role in a variety of physiological and preventative functions. The results of these studies justify the recommendation to improve the general vitamin D status in children and adults by means of a healthy approach to sunlight exposure, consumption of foods containing vitamin D and supplementation with vitamin D preparations. In general, closer attention should therefore be paid to vitamin D deficiency in medical and pharmaceutical practice than has been the case hitherto.