Medication-related osteonecrosis of the jaws after tooth extraction in senescent female mice treated with zoledronic acid: Microtomographic, histological and immunohistochemical characterization (original) (raw)

Zoledronic acid – Related osteonecrosis of the jaws. Experimental model with dental extractions in rats

Journal of Cranio-Maxillofacial Surgery, 2014

Introduction: Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a pathologic condition of increasing frequency, with a poorly understood pathophysiology and which can be difficult to manage. The aim of this study was to find a reproducible experimental model that directly relates chronic bisphosphonate administration with the development of osteonecrosis with or without tooth extraction, with no other drug involved. Material and methods: Twenty male Wistar rats were divided into 4 groups (n ¼ 5/group). Animals were injected over 9 weeks with zoledronic acid (0.1 mg/kg). In groups 1 and 2 three times a week intraperitoneally, and in group 3 once a week intravenously. A control group (group 4) received intraperitoneal injections of saline solution three times a week. After 8 weeks of treatment, 3 right upper jaw molars were extracted in groups 1, 3 and 4 and all rats were sacrificed 1 week later. The maxillae were histologically analyzed for presence of osteonecrosis foci, number of osteoclasts, vascularity, bone resorption status and presence of abscess. Radiographic examination was performed with a plain radiograph of each hemi-head. Results: We found that group 1 (dental extractions and highest cumulative dose of zoledronic acid) had the highest incidence of osteonecrosis (80%), absence of bone resorption (100%) and lowest number of osteoclasts (mean 7.9/field at 40Â). Zoledronic acid-treated groups showed variable degrees of osteosclerosis and trabecular disorganization on X-ray study. Conclusions: We offer a new animal model of BRONJ after zoledronic acid administration and dental extractions, achieving bone changes similar or superior to previous studies, highlighting the dental extraction as an important trigger factor.

Increased Numbers of Nonattached Osteoclasts After Long-Term Zoledronic Acid Therapy in Mice

Endocrinology, 2012

Osteoclasts are key players in the maintenance of bone, which is an endocrine target and organ. Bisphosphonates, used for the management of metastatic bone diseases and osteoporosis, suppress osteoclasts. However, the impact of continuously suppressed osteoclasts is unknown. In this study, mice received zoledronic acid (ZA) for 13 months, nearly half the lifespan of mice, and the effects of continual osteoclast suppression on the bone environment and oral wound healing were determined. ZA therapy suppressed osteoclasts, resulting in significantly more bone mass compared with control. Despite continuous and intense suppression of bone loss in mice receiving ZA, serum calcium levels were maintained in the normal range. No differences were noted in serum tartrate-resistant acid phosphatase (TRAP) 5b levels between ZA-treated and control mice. Histomorphometric analyses of bones revealed that ZA therapy significantly decreased osteoclasts on the bone surface but, instead, substantially increased TRAP ϩ mononuclear cells and osteoclasts that were not on the bone surface. When oral trauma was induced, such TRAP ϩ mononuclear and nonattached osteoclasts increased considerably with increased inflammatory cell infiltration in the wounds. As a result, oral wound healing was hindered at the connective tissue level. Healing of the epithelium was unaffected. These findings indicate that the continual suppression of osteoclasts does not affect serum calcium levels and that long-term ZA therapy stimulates nonattached osteoclast and TRAP ϩ mononuclear cell formation that are expanded rapidly in response to oral trauma. Caution should be exercised when using the serum TRAcP5b to estimate the efficacy of antiresorptive therapy.

Long-term therapy with intravenous zoledronate increases the number of nonattached osteoclasts

Journal of Cranio-Maxillofacial Surgery

The purpose of this study was to investigate the influence of long-term therapy with intravenous zoledronate (ZA) on the healing of extraction sockets in rats. Forty rats, divided into groups C (Control) and Z (Zoledronate), received intravenous injections of either saline solution or ZA for 24 weeks. Their right maxillary incisor was extracted. Euthanasia was performed at 7 or 28 days postoperative. Histomorphometric (Newly Formed Bone Area) and immunohistochemical (RANKL, OPG and TRAP) analyses were performed. Data were statistically analyzed (ANOVA, Tukey's test and KruskaleWallis, Dunn's Multiple Comparison test).Groups C and Z showed similar new bone area, RANKL and OPG immunolabeling. The number of TRAP-positive multinucleated cells was significantly higher in Group Z than in Group C at 28 days. A significantly higher proportion of nonattached osteoclasts were seen in Group Z than in Group C at both periods of analysis. Long-term therapy with intravenous ZA stimulated nonattached osteoclast formation in extraction sockets in rats, thus decreasing local bone resorption. However, it did not influence bone formation by osteoblasts.

Dental extraction following zoledronate, induces osteonecrosis in rat´s jaw

Medicina Oral Patología Oral y Cirugia Bucal, 2017

Background: Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ) is clinically characterized by the presence of exposed bone in the oral cavity that persists for more than eight weeks. Previous attempts to establish an animal model have not sufficiently considered disease features. Our aim was to establish an inexpensive and replicable animal model that develops BRONJ in a short time. Material and Methods: Thirty-two male Wistar rats were randomly divided into two groups: control and experimental. In the experimental group, we administered 0.06mg/kg intraperitoneal dose of zoledronic acid (ZA) 7 and 14 days prior to maxillary second molar extraction. At two, four and six weeks after tooth extraction, the animals were euthanized, and we dissected the maxilla following histological procedures. We stained serial slides with hematoxylin and eosin and Masson's trichrome. The samples were harvested for macroscopic, radiologic and histological evaluation of bone changes. Results: At two weeks postextraction, we observed exposed necrotic bone in dental socket areas in experimental groups. Radiological analysis revealed osteolytic lesions accompanied by extensive destruction and sequestrum formation in the same group. Histological examination confirmed the absence of necrotic bone in control groups in contrast with the experimental groups. The percentage of empty lacunae and the number of osteoclasts and the necrotic bone area were significantly increased (p<0.05) in the experimental groups. Conclusions: The animal model using ZA administration to prior dental extraction successfully mimicked human BRONJ lesions. Also, the model was easily replicated, inexpensive and showed different features than other previous BRONJ models.

Absence of medication-related jaw osteonecrosis after treatment with strontium ranelate in ovariectomized rats

Brazilian Oral Research

This study aimed to evaluate the potential of strontium ranelate (SR) in medication-related jaw osteonecrosis (MRONJ) after tooth extraction in ovariectomized rats. Thirty ovariectomized rats were divided into three groups (n = 10): bisphophonate (BP) group (zoledronic acid; 0.4 mg/kg/week), SR group (625 mg/kg/day), and control group (saline solution). The lower first molars were extracted after 60 days of drug therapy. Drug administration was continued for another 30 days after tooth extraction. The mandibles were subjected to clinical, histological, radiographic, and microtomographic evaluations. Only the BP group showed clinical changes, characterized by the presence of 70% (n = 7) and 20% (n = 2) of ulcers and extraoral fistulas. Radiographic evaluation demonstrated bone sequestration only in the BP group (n = 7, 70%). Microtomographic analysis revealed increased bone porosity after ovariectomy, particularly in the the control group (p < 0.05). The BP group showed a higher bone surface density, bone volume, and trabecular number than SR and control groups, but with less trabecular separation (p < 0.05). All the animals in the BP group demonstrated histological osteonecrosis. There was no evidence of osteonecrosis in the control and SR groups, which was characterized by the absence of empty osteocyte gaps and associated with the gradual healing of the extraction area. Also, an increased number of blood vessels and a reduced number of osteoclasts were observed in the SR group (p < 0.05). Therefore, SR treatment increased angiogenesis and osteoclastogenesis in the healing socket and was not associated with MRONJ development after tooth extraction in ovariectomized rats.

Delayed alveolar bone repair and osteonecrosis associated with Zoledronic Acid therapy in rats: macroscopic, microscopic and molecular analysis

Journal of Applied Oral Science, 2020

Objective: This study aims to evaluate bone repair and the development of the medication related osteonecrosis of the jaw (MRONJ) associated with the use of zoledronic acid in Wistar rats. Methodology: 48 male Wistar rats were divided into four groups: ZA, treated with intraperitoneal zoledronic acid, 0.6 mg/kg every 28 days, totaling five doses; control (C), treated with 0.9% sodium chloride; ZA-surgical (SZA) and C-surgical (SC), submitted to extraction of the right upper molars 45 days after the first application. Alveolar bone repair was evaluated by macroscopic and histological analysis. Protein expression evaluations were performed by qPCR. Results: Macroscopic evaluation showed that 91.66% (11) of the animals in the SZA group and 41.66% (5) from the SC group presented solution of epithelium continuity (P<0.05). All animals in the SZA group and none in the SC group had bone sequestration. The area of osteonecrosis was higher in the SZA group than in the SC group (P<0.05). In molecular evaluation, the SZA group presented changes in the expression of markers for osteoclasts, with increased RANK and RANKL, and a decrease in OPG. Conclusion: The results highlighted strong and evident interference of zoledronic acid in bone repair of the socket, causing osteonecrosis and delayed bone remodeling.

Comparison of the Effects of Local and Systemic Zoledronic Acid Application on Mandibular Distraction Osteogenesis

Journal of Craniofacial Surgery, 2017

Bisphosphonates are antibone resorptive drugs that are used to prevent bone tissue resorption in several skeletal diseases. The aim of this study was to examine the effects of systemic and local applications of zoledronic acid (ZA) on newly regenerated bone in a model of experimental distraction osteogenesis (DO). To do this mandibular DO was applied to 30 adult female Sprague Dawley rats, which were randomly divided into 3 groups: control, DO only, systemic zoledronic acid (SZA), and local zoledronic acid (LZA). In the LZA group, the gap between the bone fragments was filled with a gelatin sponge soaked in 2 mg of ZA and 0.1 mL of sterile saline. In the SZA group, a single dose of 0.1 mg/kg ZA was administered systemically. After the surgery, there was a 5-day latent waiting period and 10-day distraction phase. Following a 28-day consolidation period, the rats were euthanized and their mandibles were collected. The distracted bone area was seen to be filled with newly regenerated bone tissue in all 3 groups, both histologically and histomorphometrically. In addition, amounts of new bone formation, osteoblast cella, osteoclast (OC) cells, osteopontin, and vascular endothelial growth factor in the SZA and LZA groups were found to be higher when compared with the controls. Furthermore, in the SZA group, new bone formation, osteoblast, OC, osteopontin, and vascular endothelial growth factor were detected in significant amounts compared with the LZA group. Osteoclast numbers did not differ in a statistically significant manner in the SZA group with respect to the LZA group. Based on the results of this study, systemic and local applications of ZA could increase the formation of new bone in patients of DO, and systemic application is a more effective method compared with local application.

Gender- and age-related differences in osteoclast formation from circulating precursors

Journal of Endocrinology, 2002

A number of bone diseases characterised by excessive osteolysis (e.g. osteoporosis and Paget's disease) exhibit a marked gender difference in prevalence and are more common in the elderly population. Bone resorption is carried out by osteoclasts, which are formed by fusion of circulating mononuclear precursor cells of haematopoietic origin. In this study, we have determined whether there are gender-and age-related differences in osteoclast formation from circulating precursors. Peripheral blood mononuclear cells (PBMCs) were co-cultured with UMR106 osteoblast-like cells in the presence of macrophage-colony stimulating factor (M-CSF) and 1,25 dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ) or cultured alone in the presence of sRANKL (soluble receptor activator of nuclear factor B ligand) and M-CSF. As assessed by the formation of tartrate resistant acid phosphatase (TRAP)positive (TRAP + ) and vitronectin receptor-positive (VNR + ) multinucleated cells (MNCs), there was no difference in the number of circulating osteoclast precursors in males and females. Lacunar resorption carried out by osteoclasts formed from these precursors was generally increased in males compared with females (P=0·03). An increase in the number of TRAP + and VNR + MNCs formed from male PBMCs was noted in response to 1,25(OH) 2 D 3 (P<0·005). An increase in lacunar resorption in cultures of PBMCs (10 5 per well) from males was also noted in response to 10 9 M 1,25(OH) 2 D 3 (P<0·05) and sRANKL (P=0·05), but not M-CSF. The addition of dexamethasone resulted in a marked increase in osteoclast formation and lacunar resorption in both males and females. Post-menopausal females and males of comparable age showed similar levels of osteoclastogenesis. Pre-menopausal women showed similar levels of osteoclastogenesis but less resorption (P=0·01) compared with males of comparable age. These results show that there are specific gender/age-related differences in osteoclast formation and bone resorption and have implications for evaluating osteoclastogenesis in skeletal diseases such as primary osteoporosis and Paget's disease.

Original Article: Stereological Measurement of Histopathological Changes in Subcomponents of Mandibular Bone Trabeculae after Mechanical Trauma in Zoledronate-induced Rats

2024

Introduction: Stereological methods to measure structural changes play an important role for diagnosing and evaluating the healing process of diseases in organs. Zoledronate, used to treat bone diseases, causes osteonecrosis of the jaw following mechanical injuries and is a challenge in clinical settings. This experiment aimed to investigate histopathological changes in subcomponents of mandibular bone trabeculae after mechanical trauma in zoledronate-induced rats by using stereological methods. Materials and Methods: Fifty female rats (220-270g) were randomly assigned to experimental and control groups. 25 rats in the experimental group were injected 0.06 mg/kg zoledronic acid (ZA) intraperitoneally, and 25 animals in the control group were injected saline. Injection was performed once a week for 8 weeks, and then dental extraction was done for each animal. Four weeks after extraction, the rats were euthanized and the right hemimandibles were removed, decalcified, cut into serial sections at 5 microns, stained with hematoxylin-eosin, and subjected to stereological analyses. Data were analyzed by using SPSS version 26. Results: The volume of bone matrix and empty lacunae was significantly higher in experimental rats than that in controls four weeks after extraction (P < 0.05). Reduction of the volume of osteocytes, osteoblasts, osteoclasts, and Howship's lacunae in experimental group was observed when compared with the controls (P < 0.05). Conclusion: The stereological methods in the present study provided a standardized and reproducible methodology for quantitative analysis of histopathological changes and can be used as a basis for future studies investigating preventive or therapeutic strategies for Medication-Related Osteonecrosis of the Jaw (MRONJ) that are evidence-based and associated with accurate and valid data.