Etiopatogenia e tratamento da osteonecrose dos maxilares induzida por medicamentos: aspectos essenciais ao dentista / Etiopathogenesis and treatment of medication-related osteonecrosis of the jaw: essential aspects for the dentist

A osteonecrose dos maxilares induzida por medicamentos (MRONJ) caracteriza-se por exposição óssea ou osso que pode ser sondado através de fístula intra ou extraoral, em região maxilofacial, e que não cicatriza dentro de oito semanas. A MRONJ é uma condição rara e debilitante que pode causar dor, disfagia e odor desagradável na cavidade oral, afetando pacientes com histórico ou sob uso contínuo de terapia antirreabsortiva, isolada ou associada a imunomoduladores ou drogas antiangiogênicas, mas sem histórico de radioterapia nos maxilares. O objetivo desta revisão narrativa de literatura é compilar os principais aspectos sobre a etiopatogenia da MRONJ e as opções terapêuticas disponíveis. A etiologia da MRONJ é multifatorial, complexa, e não está totalmente compreendida, não havendo um tratamento definitivo, mas diversas modalidades terapêuticas que visam o controle da dor e da progressão da osteonecrose. Conclui-se com essa revisão que o entendimento da etiopatogenia da MRONJ pelo cirurgião-dentista lhe permite adotar medidas preventivas, bem como o conhecimento das modalidades terapêuticas disponíveis lhe possibilita oferecer o manejo adequado para seu paciente, conforme o estágio da doença.

Medication-related osteonecrosis of the jaw (MRONJ) is characterized by exposed bone or bone that can be probed through an intra or extraoral fistula, in the maxillofacial region, which does not heal within eight weeks. MRONJ is a rare and debilitating condition that can cause pain, dysphagia and unpleasant odor in the oral cavity, affecting patients with a history or continuous use of antiresorptive therapy, alone or associated with immunomodulators or antiangiogenic drugs, but without a history of radiotherapy to the jaws. The aim of this narrative literature review is to compile the main aspects about the etiopathogenesis of MRONJ and the available therapeutic options. The etiology of MRONJ is multifactorial, complex, and is not fully understood, with no definitive treatment, but several therapeutic modalities that aim to control pain and the progression of osteonecrosis. It is concluded from this review that the understanding of the etiopathogenesis of MRONJ by the dental surgeon allows him to adopt preventive measures, as well as the knowledge of the therapeutic modalities available allows him to offer the appropriate management for his patient, depending on the stage of the disease.

The dynamin inhibitor, dynasore, prevents zoledronate-induced viability loss in human gingival fibroblasts by partially blocking zoledronate uptake and inhibiting endosomal acidification.

OBJECTIVE: For treatment of medication-related osteonecrosis of the jaw, one proposed approach is the use of a topical agent to block entry of these medications in oral soft tissues. We tested the ability of phosphonoformic acid (PFA), an inhibitor of bisphosphonate entry through certain sodium-dependent phosphate contransporters (SLC20A1, 20A2, 34A1-3) as well as Dynasore, a macropinocytosis inhibitor, for their abilities to prevent zoledronate-induced (ZOL) death in human gingival fibroblasts (HGFs). METHODOLOGY: MTT assay dose-response curves were performed to determine non-cytotoxic levels of both PFA and Dynasore. In the presence of 50 µM ZOL, optimized PFA and Dynasore doses were tested for their ability to restore HGF viability. To determine SLC expression in HGFs, total HGF RNA was subjected to quantitative real-time RT-PCR. Confocal fluorescence microscopy was employed to see if Dynasore inhibited macropinocytotic HGF entry of AF647-ZOL. Endosomal acidification in the presence of Dynasore was measured by live cell imaging utilizing LysoSensor Green DND-189. As a further test of Dynasore's ability to interfere with ZOL-containing endosomal maturation, perinuclear localization of mature endosomes containing AF647-ZOL or TRITC-dextran as a control were assessed via confocal fluorescence microscopy with CellProfiler™ software analysis of the resulting photomicrographs. RESULTS: 0.5 mM PFA did not rescue HGFs from ZOL-induced viability loss at 72 hours while 10 and 30 µM geranylgeraniol did partially rescue. HGFs did not express the SLC transporters as compared to the expression in positive control tissues. 10 µM Dynasore completely prevented ZOL-induced viability loss. In the presence of Dynasore, AF647-ZOL and FITC-dextran co-localized in endosomes. Endosomal acidification was inhibited by Dynasore and perinuclear localization of both TRITC-dextran- and AF647-ZOL-containing endosomes was inhibited by 30 µM Dynasore. CONCLUSION: Dynasore prevents ZOL-induced viability loss in HGFs by partially interfering with macropinocytosis and by inhibiting the endosomal maturation pathway thought to be needed for ZOL delivery to the cytoplasm.

Smart Delivery of Biomolecules Interfering with Peri-Implant Repair in Osteoporotic Rats.

Bisphosphonates are widely used for the treatment of postmenopausal osteoporosis; however, they cause several long-term side effects, necessitating the investigation of local ways to improve osseointegration in compromised bone tissue. The purpose of this study was to evaluate peri-implant bone repair using implants functionalized with zoledronic acid alone (OVX ZOL group, n = 11), zoledronic acid + teriparatide (OVX ZOL + TERI group, n = 11), and zoledronic acid + ruterpy (OVX ZOL + TERPY group, n = 11) compared to the control group (OVX CONV, n = 11). Analyses included computer-assisted microtomography, qualitative histologic analysis, and real-time PCR analysis. Histologically, all functionalized surfaces improved peri-implant repair, with the OVX ZOL + TERI group standing out. Similar results were found in computerized microtomography analysis. In real-time PCR analysis, however, the OVX ZOL and OVX ZOL + TERPY groups showed better results for bone formation, with the OVX ZOL + TERPY group standing out, while there were no statistical differences between the OVX CONV and OVX ZOL + TERI groups for the genes studied at 28 postoperative days. Nevertheless, all functionalized groups showed a reduced rate of bone resorption. In short, all surface functionalization groups outperformed the control group, with overall better results for the OVX ZOL + TERI group.

Influence of zoledronic acid and low-intensity laser on collagen fibers during the bone repair process.

PURPOSE: To evaluate collagen fibers during the bone repair process in critical defects created in the tibias of rats, treated with zoledronic acid (AZ) associated with low-level laser therapy (LLLT). METHODS: Ten rats were distributed according to treatment: group 1) saline solution; group 2) LLLT; group 3) AZ; group 4) AZ and LLLT. AZ was administered at the dose of 0.035 mg/kg at fortnightly intervals over eight weeks. Next, 2-mm bone defects were created in the tibias of all animals. The bone defects in groups 2 and 4 were irradiated LLLT in the immediate postoperative period. After periods 14 and 28 of application, the animals were euthanized, and birefringence analysis was performed. RESULTS: Approximately 90% of the total area was occupied by collagen fibers within the red color spectrum, this area being statistically larger in relation to the area occupied by collagen fibers within the green and yellow spectrum, in the four groups. Over the 14-day period, there was no statistically significant difference between the groups. In the 28-day period, group 2 (14.02 ± 15.9%) was superior in quantifying green birefringent fibers compared to group 1 (3.06 ± 3.24%), with p = 0.009. CONCLUSIONS: LLLT associated with ZA is effective in stimulating the neoformation of collagen fibers. The LLLT group without the association with ZA showed a greater amount of immature and less organized matrix over a period of 28 days.

Photodynamic therapy repairs medication-related osteonecrosis of the jaw by reducing NF-kB protein in rats.

OBJECTIVE: To evaluate whether antimicrobial photodynamic therapy (aPDT) repairs bisphosphonate-related osteonecrosis of the jaw (BRONJ) modulated by the reduction of NF-kB protein in a murine model. METHODOLOGY: Male Wistar rats (N=30) were divided into the following groups (n=6/group): negative control (NC); experimental osteonecrosis (ONE); ONE + photosensitizer (PS); ONE + photobiomodulation (PBM); and ONE + aPDT. Over 8 weeks, ONE was induced by zoledronic acid 250 µg/kg injections, except in the NC group, which received sterile 0.9% saline, followed by extraction of the lower left first molar. Red light laser irradiation (wavelength ~660 nm, power 50 mW, energy of 2 J, energy dose of 66.67 J/cm2 for 40 s) was performed once a week for 4 weeks. Methylene blue 0.3% was used as PS. The animals were euthanized and examined macroscopically for the presence of exposed bone and epithelial repair and microscopically by histochemical (hematoxylin-eosin and Masson's trichrome staining) and immunohistochemical (anti-NF-kB) methods. Macroscopic and histomorphometric data were analyzed by one-way ANOVA and Tukey's post-test (p<0.05). RESULTS: Mucosal repair, viable osteocytes, and NF-kB immunostaining were observed in the NC, ONE+PS, ONE+PBM, and ONE+aPDT groups. The ONE group showed no mucosal repair, showing empty lacunae and multifocal immunostaining for NF-kB. The ONE+PBM and ONE+aPDT groups had greater deposition of extracellular matrix and less necrotic bone tissue (p<0.05). CONCLUSION: PBM and aPDT treatments for BRONJ were effective for bone and epithelial repair, in addition to reducing inflammation mediated by the decrease of NF-kB protein in the irradiated regions.

Influence of the use of bisphosphonates on the development of postextraction sequelae: Scoping review with mapping evidence of in vivo studies.

OBJECTIVE: To map the current scientific landscape regarding the association/causality of medication-related osteonecrosis of the jaw (MRONJ) after tooth extraction under bisphosphonate (BF) therapy to identify knowledge gaps and guide future research. DATA: This review used the PCC strategy (P = Patient; C = Concept; C = Context). SOURCES: The MEDLINE/PubMed, Scopus, Web of Science/Clarivate Analytics, and gray literature databases were used. STUDY SELECTION: Searches were conducted by two independent reviewers until April 2024. Studies involving prior BF use and tooth extraction in humans or animals were included. Among the 176 studies, 73 (41.4 %) were in animals, and 103 (58.5 %) were in humans. Brazil led in animal studies (n = 14; 19.1 %), while Italy led in human studies (n = 14; 13.6 %). Zoledronic acid was the most cited BF (79.4 % in animals; 34.9 % in humans), with intravenous administration being most frequent (38.3 % in animals; 35.9 % in humans). The mandible was the main extraction site (n = 36 in animals; n = 41 in humans). In 91.7 % of the animal studies, sequelae compatible with osteonecrosis signs and symptoms were observed, with bone necrosis being most common (n = 39; 53.4 %). In humans, 93.2 % of studies presented 239 sequelae, with bone necrosis (n = 53; 22.1 %) being the most cited. The main location of sequelae was the mandible (n = 36 in animals; n = 41 in humans). CONCLUSIONS: Animal studies highlighted bone exposure, notably using murine models, with a significant Brazilian contribution. In human studies, bone necrosis was the main sequela of MRONJ, which has been reported by researchers in the Italy. CLINICAL SIGNIFICANCE: These findings underscore the importance of careful consideration and monitoring of patients who have a history of bisphosphonate use and who are undergoing tooth extraction, highlighting the potential risk of MRONJ.

Polysacharide of Agaricus blazei gel mitigates bone necrosis in model of the jaws related to bisphosphonate via Wnt signaling.

To investigate de effect of PAb gel on the bone tissue of rats submitted to Bisphosphonate-related osteonecrosis of the jaws (BRONJ). Initially, 54 animals were submitted to BRONJ model by Zoledronic Acid (ZA) (0.1 mg/kg 3x/wk for 9 wk, ip), followed by the 1st upper left molar extraction at the 8th wk. After tooth removal, the animals were divided into 3 groups, ZA that received placebo gel or PAb gel that received 1% PAb gel, inside the dental alveolus. The control Group (CONTROL) received 0.1 mg/kg of 0.9% saline and then placebo gel. Three weeks after tooth extraction, the animals were euthanized, and maxillae were colleted for macroscopic, radiographic, histological and Raman spectomery assays. Additionally, GSK3b, beta-catenin, and Runx2 mRNA expressions were determined. Blood samples were collected for the analysis of Bone-specific alkaline phosphatase (BALP) levels. PAb gel improved mucosal healing, increased the number of viable osteocytes, while it reduced the number of empty lacunae, as well as the amount of bone sequestration. Furthermore, PAb gel positively influenced the number and functionality of osteoblasts by stimulating Wnt signaling, thereby inducing bone remodeling. Additionally, PAb gel contributed to improved bone quality, as evidenced by an increase in bone mineral content, a decrease in bone solubility, and an enhancement in the quality of collagen, particularly type I collagen. PAb gel mitigated bone necrosis by stimulating of bone remodeling through Wnt signaling and concurrently improved bone quality. PAb gel emerges as a promising pharmacological tool for aiding in BRONJ therapy or potentially preventing the development of BRONJ.

Ozone therapy effect in medication-related osteonecrosis of the jaw as prevention or treatment: microtomographic, confocal laser microscopy and histomorphometric analysis.

OBJECTIVE: This study aimed to evaluate the efficacy of ozone therapy in the preoperative (prevention) and/or postoperative (treatment) of MRONJ. MATERIAL AND METHODS: Forty male Wistar rats were caudally treated with zoledronic acid (ZOL) and to ozone therapy before extraction (prevention, POG), after extraction (treatment, TOG), or both (prevention and treatment, TPOG), and treated with saline (SAL). The animals received intramuscular fluorochrome (calcein and alizarin), and 28 days postoperatively, they were euthanized, and the tissues were subjected to microtomographic computed tomography (microCT), LASER confocal, and histomorphometric analyses. RESULTS: Micro-CT showed a higher bone volume fraction average in all groups than that in the ZOL group (P < 0.001), the ZOL group showed high porosity (P = 0.03), and trabecular separation was greater in the TOG group than in the POG group (P < 0.05). The mineral apposition rate of the POG group was high (20.46 ± 6.31) (P < 0.001), followed by the TOG group (20.32 ± 7.4). The TOG group presented the highest mean newly formed bone area (68.322 ± 25.296) compared with the ZOL group (P < 0.05), followed by the SAL group (66.039 ± 28.379) and ZOL groups (60.856 ± 28.425). CONCLUSIONS: Ozone therapy modulated alveolar bone repair in animals treated with ZOL, mainly after surgery trauma, leading to bone formation as healing tissue. CLINICAL RELEVANCE: Osteonecrosis has been a challenge in dentistry, and owing to the lack of a consensus regarding therapy, studies presenting new therapies are important, and ozone has been one of the therapies explored empirically.

Peri-implantitis increases the risk of medication-related osteonecrosis of the jaws associated with osseointegrated implants in rats treated with zoledronate.

This study evaluated the peri-implant tissues under normal conditions and under the influence of experimental peri-implantitis (EPI) in osseointegrated implants installed in the maxillae of rats treated with oncologic dosage of zoledronate. Twenty-eight senescent female rats underwent the extraction of the upper incisor and placement of a titanium dental implant (DI). After eight weeks was installated a transmucosal healing screw on DI. After nine weeks, the following groups were formed: VEH, ZOL, VEH-EPI and ZOL-EPI. From the 9th until the 19th, VEH and VEH-EPI groups received vehicle and ZOL and ZOL-EPI groups received zoledronate. At the 14th week, a cotton ligature was installed around the DI in VEH-EPI and ZOL-EPI groups to induce the EPI. At the 19th week, euthanasia was performed, and the maxillae were processed so that at the implanted sites were analyzed: histological aspects and the percentage of total bone tissue (PTBT) and non-vital bone tissue (PNVBT), along with TNFα, IL-1ß, VEGF, OCN and TRAP immunolabeling. ZOL group presented mild persistent peri-implant inflammation, higher PNVBT and TNFα and IL-1ß immunolabeling, but lower for VEGF, OCN and TRAP in comparison with VEH group. ZOL-EPI group exhibited exuberant peri-implant inflammation, higher PNVBT and TNFα and IL-1ß immunolabeling when compared with ZOL and VEH-EPI groups. Zoledronate disrupted peri-implant environment, causing mild persistent inflammation and increasing the quantity of non-vital bone tissue. Besides, associated with the EPI there were an exacerbated inflammation and even greater increase in the quantity of non-vital bone around the DI, which makes this condition a risk factor for medication-related osteonecrosis of the jaws.

Twenty-four months of follow-up in women with rebound-associated vertebral fractures after discontinuation of denosumab: a single-centre case series.

Evidence on the management of rebound-associated vertebral fractures after denosumab discontinuation is scarce. This study describes seven patients retreated with denosumab, teriparatide or zoledronate for 24 months. Their bone mineral density remained stable or improved and no new fractures occurred suggesting that all three options might be adequate for their treatment. PURPOSE: To describe the densitometric and biochemical changes achieved with osteoactive treatment after 24 months of follow-up in patients who suffered rebound-associated vertebral fractures (RAVFs) after Dmab discontinuation, and to report the occurrence of new vertebral and non-vertebral fractures. METHODS: Patients with RAVFs who received retreatment (RT) for 24 months were included. Bone mineral density (BMD) was assessed by dual-energy x-ray absorptiometry at the lumbar spine (LS), femoral neck (FN) and total hip (TH), along with C-terminal cross-linked telopeptide of type I collagen, osteocalcin, and bone alkaline phosphatase. Data were collected at the start of the RT and after 24 months. RESULTS: Seven female patients were included. RT consisted in Dmab (n = 3), teriparatide (TPT) (n = 3) and zoledronate (Zol) (n = 1). At 24 months, the mean BMD change was 2.2% at LS, 6.8% at FN and 3.8% at TH in the Dmab group, 7.5% at LS, 1.4% at FN and 3.7% at TH in the TPT group and, 5.0% at LS, 0.6% at FN and 3.9% at TH in the patient with Zol. After 24 months of follow-up, no patient suffered new fractures. CONCLUSION: In this series of patients with RAVFs, we did not observe any new fractures and the BMD remained stable after 24 months of RT. Future studies are needed to evaluate the most suitable treatment approach after RAVFs but these preliminary data suggest that all denosumab, zoledronate and teriparatide might be adequate options.

Ozone Improved Bone Dynamic of Female Rats Using Zoledronate.

The aim of this study was to analyze the effect of ozone (OZN) therapy on the dynamics of bone tissue in ovariectomized rats treated with zoledronic acid (ZOL). Female Wistar rats aged 6 months (n = 110) were subjected to bilateral ovariectomy (OVX). At month 3 post-OVX, 10 animals were euthanized to characterize the bone tissue architecture using microtomography (micro-CT). The remaining animals were divided into two groups: ZOL group, administered with ZOL (100 µg/kg body weight); saline (SAL) group (0.45 mL of SAL solution), both for 28 days. At month 3 post-treatment, 10 animals from each group were euthanized to characterize the bone architecture using micro-CT. The remaining animals were divided into the following groups: ZOL (n = 20), ZOL + OZN (n = 20); SAL (n = 20), and SAL + OZN (n = 20). The animals in ZOL + OZN and SAL + OZN groups were intraperitoneally administered with OZN (0.7 mg/kg body weight) once every 2 days. On days 30 and 60, six animals from each group were euthanized for analysis and structural characterization of bones in the femoral head and spine. Some samples of the femoral neck were subjected to biomechanical tests, while some samples were analyzed under a laser confocal microscope. The other samples collected from the femoral neck and spine were analyzed for area of neoformed bone and used for performing inflammatory cell and osteocyte counts. Data were submitted to statistical analysis considering a significance level of p < 0.05. Bone volume percentage and osteocyte and inflammatory cell counts were upregulated in the femoral head region of the ZOL + OZN group. Biomechanical analysis of the femoral neck revealed that the modulus of elasticity was similar between the ZOL and ZOL + OZN groups but differed significantly between the SAL and SAL + OZN groups. The positive areas for calcein and alizarin in the ZOL and ZOL + OZN groups were higher than those in the SAL and SAL + OZN groups. This suggested a positive synergistic effect of OZN and ZOL on the maintenance of bone mass and restoration of bone tissue vitality in ovariectomized rats.

Rodents as an animal model for studying tooth extraction-related medication-related osteonecrosis of the jaw: assessment of outcomes.

OBJECTIVE: To assess the outcomes of several rodent animal models for studying tooth extraction-related medication-related osteonecrosis of the jaw (MRONJ). DESIGN: After a search of the databases, 2004 articles were located, and 118 corroborated the inclusion factors (in vivo studies in rodents evaluating tooth extraction as a risk factor for the development of MRONJ). RESULTS: Numerous studies attempting to establish an optimal protocol to induce MRONJ were found. Zoledronic acid (ZA) was the most used drug, followed by alendronate (ALN). Even when ZA did not lead to the development of MRONJ, its effect compromised the homeostasis of the bone and soft tissue. The association of other risk factors (dexamethasone, diabetes, and tooth-related inflammatory dental disease) besides tooth extraction also played a role in the development of MRONJ. In addition, studies demonstrated a relationship between cumulative dose and MRONJ. CONCLUSIONS: Both ZA and ALN can lead to MRONJ in rodents when equivalent human doses (in osteoporosis or cancer treatment) are used. Local oral risk factors and tooth-related inflammatory dental disease increase the incidence of MRONJ in a tooth extraction-related rodent model.

Influence of zoledronic acid and low-intensity laser on collagen fibers during the bone repair process

Purpose: To evaluate collagen fibers during the bone repair process in critical defects created in the tibias of rats, treated with zoledronic acid (AZ) associated with low-level laser therapy (LLLT). Methods: Ten rats were distributed according to treatment: group 1) saline solution; group 2) LLLT; group 3) AZ; group 4) AZ and LLLT. AZ was administered at the dose of 0.035 mg/kg at fortnightly intervals over eight weeks. Next, 2-mm bone defects were created in the tibias of all animals. The bone defects in groups 2 and 4 were irradiated LLLT in the immediate postoperative period. After periods 14 and 28 of application, the animals were euthanized, and birefringence analysis was performed. Results: Approximately 90% of the total area was occupied by collagen fibers within the red color spectrum, this area being statistically larger in relation to the area occupied by collagen fibers within the green and yellow spectrum, in the four groups. Over the 14-day period, there was no statistically significant difference between the groups. In the 28-day period, group 2 (14.02 ± 15.9%) was superior in quantifying green birefringent fibers compared to group 1 (3.06 ± 3.24%), with p = 0.009. Conclusions: LLLT associated with ZA is effective in stimulating the neoformation of collagen fibers. The LLLT group without the association with ZA showed a greater amount of immature and less organized matrix over a period of 28 days.

Long-term consequences of osteoporosis therapy with bisphosphonates.

Bisphosphonates (BPs) are medications widely used in clinical practice to treat osteoporosis and reduce fragility fractures. Its beneficial effects on bone tissue have been consolidated in the literature for the last decades. They have a high affinity for bone hydroxyapatite crystals, and most bisphosphonates remain on the bone surface for a long period of time. Benefits of long-term use of BPs: Large and important trials (Fracture Intervention Trial Long-term Extension and Health Outcomes and Reduced Incidence with Zoledronic acid Once Yearly-Pivotal Fracture Trial) with extended use of alendronate (up to 10 years) and zoledronate (up to 6 years) evidenced significant gain of bone mineral density (BMD) and vertebral fracture risk reduction. Risks of long-term use of BPs: The extended use of antiresorptive therapy has drawn attention to two extremely rare, although severe, adverse events. That is, atypical femoral fracture and medication-related osteonecrosis of the jaw are more common in patients with high cumulative doses and longer duration of therapy. BPs have demonstrated safety and effectiveness throughout the years and evidenced increased BMD and reduced fracture risks, resulting in reduced morbimortality, and improved quality of life. These benefits overweight the risks of rare adverse events.

Interleukin-17 plays a role in dental pulp inflammation mediated by zoledronic acid: a mechanism unrelated to the Th17 immune response?

OBJECTIVE: To evaluate the influence of RORγT inhibition by digoxin on inflammatory changes related to interleukin-17 (IL-17) in the pulp of rats treated with zoledronate (ZOL). METHODOLOGY: Forty male Wistar rats were divided into a negative control group (NCG) treated with saline solution, a positive control group (PCG) treated with ZOL (0.20 mg/kg), and three groups treated with ZOL and co-treated with digoxin 1, 2, or 4 mg/kg (DG1, 2, and 4). After four intravenous administrations of ZOL or saline solution in a 70-day protocol, the right molars were evaluated by histomorphometry (number of blood vessels, blood vessels/µm2, cells/µm2, total blood vessel area, and average blood vessel area) and immunohistochemistry (IL-17, TNF-α, IL-6, and TGF-ß). The Kruskal-Wallis/Dunn test was used for statistical analysis. RESULTS: PCG showed an increase in total blood vessel area (p=0.008) and average blood vessel area (p=0.014), and digoxin treatment reversed these changes. DG4 showed a reduction in blood vessels/µm2 (p<0.001). In PCG odontoblasts, there was an increase in IL-17 (p=0.002) and TNF-α (p=0.002) immunostaining, and in DG4, these changes were reversed. Odontoblasts in the digoxin-treated groups also showed an increase in IL-6 immunostaining (p<0.001) and a reduction in TGF-ß immunostaining (p=0.002), and all ZOL-treated groups showed an increase in IL-17 (p=0.011) and TNF-α (p=0.017) in non-odontoblasts cells. CONCLUSION: ZOL induces TNF-α- and IL-17-dependent vasodilation and ectasia, and the classical Th17 response activation pathway does not seem to participate in this process.

Zoledronate treatment exerts sex-independent effects on bone and dental physicochemical properties in mice jaw necrosis.

INTRODUCTION: Bisphosphonate (BF) therapy is strongly related to the occurrence of medication-related osteonecrosis of the jaw (ONJ). However, no previous study has evaluated if there are sex-related differences on the ONJ establishment together with bone biomechanical alterations, and if they could have a synergy with the ZA treatment. MATERIALS AND METHODS: This study aimed to analyze the physicochemical properties of mineralized tissues in a zoledronate (ZA)-related osteonecrosis mouse model, by a 2 × 2-factorial design, considering sex (female/male) and treatment (ZA/Saline) factors (n = 8/group). After three ZA (1.0 mg/kg) or saline administrations (days 0, 7, 14), the lower left second molar was extracted (day 42). Further ZA administration (day 49) and euthanasia (day 70) were conducted. After confirmation of ZA-induced jaw necrosis (histologic and microtomographic analysis), spectroscopic and mechanical parameters were assessed. RESULTS: ZA-treated groups presented lower bone density due to impaired healing of tooth extraction socket. Sex-related alterations were also observed, with lower bone density in females. Regarding biomechanical parameters, sex and treatment exerted independent influences. ZA, although decreasing flexural modulus and yield stress, increases stiffness mainly due to a higher bone volume. Females show less resistance to higher loads compared to males (considering dimension-independent parameters). Additionally, ZA increases crystallinity in bone and dental structure (p < 0.05). In summary, although strongly related to osteonecrosis occurrence, ZA modifies bone and dental mineral matrix, improving bone mechanical properties. CONCLUSION: Despite sex-dependent differences in bone biomechanics and density, osteonecrosis was established with no sex influence. No synergistic association between sex and treatment factors was observed in this study.

Esclerosis bilateral de huesos largos: enfermedad de Erdheim-Chester. Reporte de un caso / Bilateral long bone sclerosis: Erdheim-Chester disease. Case report

La enfermedad de Erdheim-Chester (EEC) es una patología poco frecuente, caracterizada por presentar infiltración xantogranulomatosa sistémica, con afección de diversos sistemas incluido el óseo. La EEC se encuentra descripta dentro de las enfermedades osteocon-densantes (EO), las cuales se reconocen por presentar aumento de la masa ósea y compromiso tanto de huesos largos como planos. La presentación clínica de la EEC es variada: puede presentar desde un curso indolente hasta manifestaciones multisistémicas. Las características radiológicas son de gran importancia para establecer su diagnóstico. Presentamos una paciente con EEC, con esclerosis bilateral de huesos largos, que exhibe algunas características diferenciales con relación a otros casos reportados: a) afectación exclusivamente ósea a 10 años de evolución, b) compromiso bilateral y simétrico de distinta magnitud, c) esclerosis cortical endóstica y perióstica, d) signos radiológicos sugestivos de periostitis, d) ausencia de compromiso metafisario, e) ausencia de actividad metabólica de las lesiones en las imágenes de 18F-FDG PET/CT.Conclusión: la presencia de lesiones osteocondensantes bilaterales exclusivamente en huesos largos deben hacer sospechar EEC. La ausencia de compromiso metafisario y de actividad metabólica en 18F-FDG PET/CT ha sido raramente descripta. (AU)

Erdheim - Chester disease (ECD) is a rare disease, characterized by systemic xanthogranulomatous infiltration, with involvement of various organs including bone. ECD is described within the sclerosing bone disorders, which are recognized for presenting increased bone mass and involvement of both long and flat bones. The clinical presentation of ECD is diverse, ranging from an asymptomatic course to multisystemic manifestations. Radiological features are of great importance to establish the diagnosis. We describe here a patient with ECD, with bilateral sclerosis of long bones that presents some differential characteristics in relation to other reported cases: a) exclusively bone involvement at 10 years of evolution, b) bilateral and symmetric involvement of different magnitude, c) endosteal and periosteal cortical sclerosis d) radiological signs suggestive of periostitis, d) absence of metaphyseal involvement, e) absence of metabolic activity of the lesions in 18F-FDG PET/CT.Conclusion: the presence of bilateral osteosclerosis exclusively in long bones should lead to suspect ECD. The absence of metaphyseal involvement and metabolic activity in 18F-FDG PET/CT have been rarely described. (AU)

Risk Factors for Bisphosphonate-Related Osteonecrosis of the Jaws in Bone Metastatic Breast and Prostate Cancer under Zoledronate Treatment: A Retrospective Analysis from 10 Years of Evaluation.

OBJECTIVE: This study aims to analyze the risk factors for BRONJ in patients taking zoledronic acid (ZA) for metastatic breast and prostate cancer. METHODS: For this, a retrospective, quantitative, observational cohort study was conducted using data on adverse effects in the oral cavity in patients during chemotherapy for treatment of solid tumors available in the electronic patient record system of the Haroldo Juaçaba Hospital/Ceará Cancer Institute in the period from 2010, to 2019. Data were tabulated in Excel and exported to SPSS v20.0 software for statistical analysis, with 95% confidence. RESULTS: Thus, it can be observed that the prevalence of BRONJ in patients under treatment for breast cancer and prostate cancer was <7%, with age <50 years of age (p=0.009), cytotoxic chemotherapy such as methotrexate (p=0.023), paclitaxel (p=0.005), capecitabine (p<0.001), gemcitabine (p=0.007) and bicalutamide (p=0.016), amount of ZA infusions (p<0.001) and hormone therapy (p=0.007), in addition, a slight reduction in survival and increased use of antidepressants (p=0.014) were observed. The reduced overall survival and increased use of antidepressants in patients who developed BRONJ, reinforcing the need for further research to study the mechanisms involved in the unconventional risk factors for BRONJ. CONCLUSION: Thus, increasing the attention to these patients to prevent this condition from compromising the prognosis of these individuals.

Naringenin and proanthocyanidins pre-treatment decreases synthesis and activity of gelatinases induced by zoledronic acid in a dental implant surface in vitro model.

OBJECTIVE: To assess the effects of pre-treatment with proanthocyanidins (PA) flavonoids, from grape seed extract, and synthetic naringenin (NA) on the synthesis of matrix metalloproteinases (MMPs) gelatinases and their tissue inhibitors (TIMPs), as well as the gelatinolytic activity of MMPs by human gingival fibroblasts (HGF) and osteoblasts (Ob) exposed to zoledronic acid (ZA) in a dental implant surface in vitro model. DESIGN: The highest non-cytotoxic concentrations of NA and PA were determined for HGF (10 µg/mL; defined by previous study) and Ob (0.5 µg/mL; defined by prestoBlue assay). Then, HFG and Ob were individually seeded onto titanium discs, and after 24 h, cells were pre-treated (or not) with NA or PA, followed (or not) by exposure to ZA. Next, MMP-2, MMP-9, TIMP-1, TIMP-2 synthesis (ELISA), and gelatinolytic activity (in situ zymography) was evaluated. Data were analyzed by one-way ANOVA and Tukey tests (α = 0.05). RESULTS: ZA treatment increased the synthesis (p < 0.05) and activity of MMPs; flavonoids pre-treatment controlled ZA-induced gelatinolytic effects, down-regulating MMPs synthesis (p < 0.05) and activity by HGF and Ob. For HGF, NA and PA pre-treatment did not up-regulate TIMP synthesis after ZA exposure (p > 0.05); for Ob, TIMP-2 was up-regulated (p < 0.05) by flavonoids, followed by ZA. CONCLUSIONS: NA and PA pre-treatment provides interesting results in the modulation of ZA deleterious effects, down-regulating MMP-2 and MMP-9 synthesis and activity by HGF and Ob and up-regulating TIMP-2 by Ob.

A colloidal hydrogel-based drug delivery system overcomes the limitation of combining bisphosphonates with bioactive glasses: in vitro evidence of a potential selective bone cancer treatment allied with bone regeneration.

Bisphosphonates are a class of drugs that induce bone cancer cell death and favor bone regeneration, making them suitable for bone cancer treatment. However, when combined with bioactive glasses to enhance bone regeneration, a chemical bond between biphosphonates and the glass surface inactivates their mechanism of action. A new colloidal hydrogel-based drug delivery system could overcome that limitation once bisphosphonates, such as zoledronic acid (ZA), are incorporated into hydrogel micelles, avoiding their interaction with the glass surface. In this work, we proposed formulations based on a poloxamer 407 thermo-responsive hydrogel matrix containing holmium-doped bioactive glass nanoparticles and different concentrations (0.05 and 5 mg/mL) of ZA. We characterized the influence of the glass and the ZA on the hydrogel properties. In addition, a drug concentration screening was performed, and biological characterizations evaluated the best result. The biological characterization consisted of evaluating cytotoxicity and in vitro bone regeneration ability through cell migration and quantification of genes related to osteogeneses through RT-PCR. The results suggest that the addition of glasses and ZA to the poloxamer did not significantly influence the sol-gel transition of the hydrogels (around 13 °C) regardless of the ZA content. However, the ZA at high concentration (PL-ZA100) decreased the enthalpy of gel formation from 68 to 43 kJ.mol-1 when compared with the pure hydrogel formulation (PL), suggesting a water structurer role of ZA, which is withdrawn when glass particles are added to the system (PL-BG5Ho-ZA100). Solid-state 31P nuclear resonance spectroscopy results showed that part of the ZA is chemically bonded to the glass surface, which explains the withdrawal in the water structurer role of ZA when the glasses were incorporated into the hydrogel. Besides, based on the drug release results, we proposed a model where part of the ZA is "free," encapsulated in the hydrogel matrix, while another part of the ZA is bonded to the glass surface. Finally, considering the in vitro results and our proposed model, the ratio between "free" and "bonded" ZA in our drug delivery systems showed in vitro evidence of a cancer treatment that selectively kills osteosarcoma cells while still favoring an osteogenic microenvironment. By overcoming the limitation of combining bisphosphonates with bioactive glasses, hydrogel-based drug delivery systems can be a solution for the development of new formulations proposed for bone cancer treatment in conjunction with bone regeneration.