O papel da infecção e inflamação na etiopatogênese da osteonecrose dos maxilares induzida por medicamentos / The role of infection and inflammation in the etiopathogenesis of medication-related osteonecrosis of the jaw

Objetivo: O objetivo desta revisão de literatura é evidenciar o papel da infecção e inflamação na etiopatogenia da osteonecrose dos maxilares induzida por medicamentos (MRONJ). Revisão da literatura: A MRONJ é uma condição rara e grave que impacta negativamente a vida dos pacientes afetados. Sua etiopatogenia é multifatorial e ainda não foi totalmente compreendida. Uma das hipóteses propostas para explicá-la sugere que, além da inibição do turnover ósseo pelos medicamentos antirreabsortivos, a infecção associada à exodontia e a inflamação local desempenham papel decisivo no desencadeamento da condição. O entendimento da etiopatogenia da MRONJ permite ao cirurgião-dentista a identificação dos pacientes com risco maior para a doença, assim como o auxilia no monitoramento e escolha do manejo mais adequado. No campo da pesquisa, ele pode aprimorar estudos pré-clínicos e aprofundar a investigação de biomarcadores para diagnóstico precoce de MRONJ. Considerações finais: Conhecer a contribuição da infecção e inflamação na etiopatogênese da MRONJ é fundamental para orientar a pesquisa e a adoção de estratégias preventivas para os pacientes em risco, e de manejo e monitoramento adequado para aqueles já acometidos. (AU)

Aim: The aim of this literature review is to highlight the role of infection and inflammation in the etiopathogenesis of drug-induced osteonecrosis of the jaw (MRONJ). Literature review: MRONJ is a rare and serious condition that negatively impacts the lives of affected patients. Its etiopathogenesis is multifactorial and has not yet been fully understood. One of the hypotheses proposed to explain it suggests that, in addition to the inhibition of bone turnover by antiresorptive drugs, the infection associated with tooth extraction and local inflammation play a decisive role in triggering the condition. Understanding the etiopathogenesis of MRONJ allows the dentist to identify patients at higher risk for the disease, as well as assisting in monitoring and choosing the most appropriate management. In research, it can improve preclinical studies and deepen the investigation of biomarkers for early diagnosis of MRONJ. Conclusion: Knowing the contribution of infection and inflammation in the etiopathogenesis of MRONJ is essential to guide research and the adoption of preventive strategies for patients at risk, and adequate management and monitoring for those already affected.(AU)

Osteonecrosis maxilar relacionada con medicamentos en pacientes oncológicos con metástasis óseas: resolución de dos casos / Medication-related osteonecrosis of the jaw in oncological patients with bone metastases: resolution of two cases

La osteonecrosis maxilar relacionada con medicamentos (ONMM) es una patología de características clínicas objetivas con signo-sintomatología patognomónica. El criterio clínico aceptado es la presencia de hueso necrótico expuesto y visible sobre el reborde óseo maxilar que no ha cicatrizado luego de 8 semanas, en pacientes con antecedentes de tratamiento antirresortivo. La denominación "relacionada con medicamentos" se utiliza por el creciente número de casos asociados con otros fármacos antirresortivos como denosumab y con terapias antiangiogénicas, más allá de la conocida relación con bifosfonatos.Si bien la incidencia de ONMM en pacientes tratados por osteopatías metabólicas es muy baja, la situación se torna más compleja en pacientes oncológicos con altas dosis de antirresortivos para tratamiento de metástasis ósea. Varios in-formes de casos describen cuadros de ONMM en pacientes con cáncer que reciben terapias dirigidas, específicamente TKI (inhibidores de tirosina quinasa) y anticuerpos monoclonales-VEGF (anticuerpos dirigidos al factor de crecimiento del endotelio vascular). La ONMM afecta negativamente la calidad de vida del paciente oncológico y produce comorbilidad significativa. Resulta imperioso identificar a los pacientes en riesgo y diseñar un protocolo de atención odontológica específico para estos casos. En este artículo se presentan dos casos de ONMM asociado con altas dosis de denosumab y administración simultánea de anticuerpos monoclonales específicos para el tratamiento del cáncer. Ambos casos sorprenden por la prematura instalación de la necrosis y su cuadro insidio-so. El protocolo de tratamiento descripto permitió controlar el cuadro inicial, limitar el avance de la lesión, asegurar el control del dolor y la infección, y finalmente, la curación total de la lesión. (AU)

Medication-related osteonecrosis of the jaws (MRONJ) is a pathology with objective clinical characteristics, with pathognomonic signs and symptoms. The accepted clinical criterion is the presence of exposed and visible necrotic bone on the maxillofacial region that has not healed after 8 weeks, in patients with history of antiresorptive treatment.The name "medication-related" is justified by the growing number of cases associated with other antiresorptive drugs such as denosumab and antiangiogenic therapies, beyond the known relationship with bisphosphonates. Although the incidence of MRONJ in patients treated for metabolic osteopathies is very low, the situation becomes more complex in cancer patients who receive high doses of antiresorptives for the treatment of skeletal metastases. Several case reports describe the presence of MRONJ in cancer patients receiving targeted therapies, specifically TKI (tyrosine kinase inhibitors) and monoclonal antibodies-targeting VEGF (vascular endothelial growth factor). MRONJ negatively affects the quality of life in cancer patients and produces significant comorbidity. It is imperative to identify patients at risk and design a specific dental care strategy for these cases.In this article, we present two cases of MRONJ associated with high doses of Denosumab and simultaneous administration of specific monoclonal antibodies. Both cases are surprising due to premature onset of necrosis. The described treatment strategies made it possible to control the initial symptoms, limit the lesion progression, ensure pain and infection control, and finally, the total healing of the lesion. (AU)

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

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.

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

Abstract 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.

Osteonecrosis de los maxilares asociada a medicamentos (ONMM): guía redactada por expertos invitados por la Asociación Argentina de Osteología y Metabolismo Mineral y por la Sociedad Argentina de Osteoporosis / Medication-related osteonecrosis of the jaw (MRONJ): guideline prepared by experts invited by the Argentine Association of Osteology and Mineral Metabolism, and the Argentine Society for Osteoporosis

La osteonecrosis maxilar asociada a medicamentos (ONMM=MRONJ como se conoce en la literatura en inglés) se define como un área ósea expuesta al medio bucal con más de ocho semanas de permanencia, en pacientes tratados con antirresortivos y/o antiangiogénicos y sin antecedentes de radioterapia en cabeza y cuello. Las fracturas ocasionan una morbimortalidad significativa y los antirresortivos son drogas eficaces y seguras para prevenirlas. Se utilizan principalmente en osteoporosis, pero también en enfermedades oncológicas como mieloma múltiple o metástasis óseas de tumores sólidos. La posología varía según el contexto clínico, siendo mayor la dosis y frecuencia de administración en oncología. Los antirresortivos actualmente más utilizados son los bifosfonatos (BF) y el denosumab (Dmab). Si bien los BF persisten largo tiempo en el tejido óseo, el Dmab tiene un mecanismo de acción reversible y su suspensión abrupta conlleva importante pérdida de masa ósea y riesgo aumentado de fracturas vertebrales múltiples. Ninguna droga puede ser suspendida ni espaciada sin autorización médica, dado que no es de competencia del odontólogo. El diagnóstico presuntivo de ONMM debe ser confirmado clínicamente por un odontólogo, quien solicitará imágenes radiológicas para establecer el estadio de la lesión. La anamnesis correcta permite establecer un diagnóstico diferencial entre ONMM, osteomielitis y osteorradionecrosis. La presentación clínica es variable y puede mostrar distintos estadios. La mayoría de los casos están precedidos por un procedimiento quirúrgico odontológico. Suele ser asintomática, aunque puede haber dolor si se localiza cerca de una estructura neuronal. La localización es variable: 62,3% se produce en el maxilar inferior. La incidencia de ONMM es baja, en un rango de 0,001 a 0,01% y tiene relación con las dosis y el tiempo de administración. La remoción de caries, la operatoria dental, la endodoncia y la rehabilitación protética fija o removible no se asocian a riesgo de ONMM. Con menos de 3 años de tratamiento antirresortivo se pueden efectuar terapéuticas quirúrgicas como exodoncias, apicectomías, cistectomías, tratamientos periodontales de raspaje y alisado subgingival sin riesgo. Con más de 3 años se aconseja evitar la realización de exodoncias y manipulación de tejido óseo. Ante la necesidad de realizar un procedimiento odontológico, no hay evidencia que avale que la suspensión transitoria del tratamiento antirresortivo pueda reducir el riesgo. Tampoco la medición de marcadores de remodelado óseo aporta datos de utilidad. Existen pocos datos en la literatura sobre la colocación de implantes dentales en pacientes que reciben drogas antirresortivas en dosis bajas; si bien existe ONMM asociada, su incidencia sería baja. Antes de iniciar un tratamiento antirresortivo se recomienda realizar interconsulta con el odontólogo para evaluar potenciales necesidades quirúrgicas. Quienes reciben antirresortivos deben realizar controles orales periódicos (semestrales) y, ante cualquier síntoma compatible con un estadio incipiente de ONMM, deben consultar a su odontólogo. El trabajo conjunto del médico y el odontólogo puede prevenir la aparición de la ONMM, un evento infrecuente, pero que puede generar elevada morbilidad en los pacientes. La comunicación fluida entre profesionales tenderá a evitar no solo la incertidumbre y desconfianza de los pacientes, sino también que se produzcan lesiones con la consecuente necesidad de tratamientos de mayor complejidad. (AU)

Medication-Related Osteonecrosis of the Jaw (MRONJ) is defined as a bone area exposed to the oral environment lasting more than eight weeks, in patients treated with antiresorptive and/or antiangiogenic drugs and without a history radiation therapy to the head and neck. Fractures cause significant morbidity and mortality, and antiresorptives are effective and safe drugs to prevent them. They are used to treat not only osteoporosis but also oncological diseases such as multiple myeloma or bone metastases from solid tumors. The dosage varies according to the clinical context; doses and frequencies of administration are higher in oncology. The most commonly used antiresorptive medications are bisphosphonates (BP) and denosumab (Dmab). Whereas BP persist for a long time in bone tissue, Dmab has a reversible mechanism of action and its discontinuation leads to significant loss of bone mass and an increased risk of multiple vertebral fractures. No drug can be suspended or spaced without medical authorization. Dentists should not take decisions about antiresorptive prescription. The presumptive diagnosis of MRONJ must be clinically confirmed by a dentist, who will order radiological studies to establish the stage of the injury. The correct anamnesis helps differentiate MRONJ from osteomyelitis and osteoradionecrosis. Clinical presentation is variable and can present different stages. Most of the cases are preceded by a dental surgical procedure. Usually MRONJ is asymptomatic although patients may feel pain if it is located near a neuronal structure. The location is variable: 62.3% occurs in the lower jaw. The incidence of MRONJ is low, in the range of 0.001 to 0.01%, and is related to the dose and time of administration. Caries removal, dental surgery, endodontics, fixed or removable prosthetic rehabilitation are not associated with risk of MRONJ. With less than 3 years of antiresorptive treatment, surgical therapies such as extractions, apicectomies, cystectomies, periodontal scaling treatments and subgingival smoothing can be performed without risk. With more than 3 years, it is advisable to avoid performing extractions and manipulating bone tissue. Given the need to perform a dental procedure, there is no evidence to support that the temporary suspension of antiresorptive treatment can reduce the risk. Nor does the measurement of bone turnover markers provide useful information. There are few data in the literature on the placement of dental implants in patients receiving antiresorptive drugs at low doses; although there might be an associated risk of MRONJ, its incidence appears to be low. Before starting antiresorptive treatment, consultation with the dentist is recommended to evaluate potential surgical needs. Patients receiving treatment with antiresorptive agents should undergo periodic oral controls (every six months) and in the event of any symptoms compatible with an early MRONJ stage, they should consult their dentists. The collaboration between physician and dentist can prevent the appearance of MRONJ, that is an infrequent event, but can generate high morbidity in patients. Fluid communication between professionals will tend to avoid, not only the uncertainty and distrust of patients, but also the occurrence of injuries needing complex treatments. (AU)

Systemic administration of quality- and quantity-controlled PBMNCs reduces bisphosphonate-related osteonecrosis of jaw-like lesions in mice.

BACKGROUND: Definitive treatment strategies for bisphosphonate-related osteonecrosis of the jaw (BRONJ) have not been developed. Cell-based therapy is an attractive treatment method for intractable diseases in the medical and dental fields; however, approval has been challenging in dentistry. Recently, we developed quality- and quantity (QQ)-controlled peripheral blood mononuclear cells (PBMNCs) that have anti-inflammatory and pro-angiogenesis effects. The aim of this study was to investigate the effects of QQ-controlled PBMNC transplantation on BRONJ-like lesions in mice. METHODS: To create high-prevalence BRONJ-like lesions, cyclophosphamide (CY) and zoledronate (ZA) were used with tooth extraction. Drug treatment was performed for 5 weeks. QQ-controlled PBMNC transplantation was performed immediately following tooth extraction of both maxillary first molars at 3 weeks after drug administration. Mice were euthanized at 2 weeks post-extraction. Histomorphometric and immunohistochemical analyses, microcomputed tomography assessment, and quantitative polymerase chain reaction evaluation were conducted using maxillae and long bones. RESULTS: ZA effects on long bones were noted, regardless of CY. Severely inhibited osseous and soft tissue wound healing of tooth extraction sockets was induced by CY/ZA combination therapy, which was diagnosed as BRONJ-like lesions. QQ-controlled PBMNC transplantation reduced BRONJ-like lesions by improving soft tissue healing with increased M1 and M2 macrophages and enhanced neovascularization in the connective tissue of tooth extraction sockets. QQ-controlled PBMNC transplantation also reduced inflammation by decreasing polymorphonuclear cells and TNF-α expression in the tooth extraction sockets. Additionally, QQ-controlled PBMNC transplantation partially improved osseous healing of tooth extraction sockets. Interestingly, only 20,000 QQ-controlled PBMNCs per mouse induced these transplantation effects. QQ-controlled PBMNC transplantation did not affect the systemic microenvironment. CONCLUSIONS: Our findings suggest that transplantation of a small amount of QQ-controlled PBMNCs may become novel therapeutic or prevention strategies for BRONJ without any adverse side effects.

Treatment of bisphosphonate-related osteonecrosis using platelet-rich plasma: microtomographic, microscopic, and immunohistochemical analyses.

The present study aimed to investigate the use of platelet-rich plasma (PRP) on tooth extraction sites in rats treated with bisphosphonates. Thirty Albinus Wistar male rats were administered 0.035 mg/kg zoledronic acid intravenously for 8 weeks, divided into four administrations with a 2-week interval between each application, after which their upper right central incisors were extracted to induce the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ). The samples were divided into the following two groups: Group 1 (G1) underwent marginal resection of BRONJ followed by the use of PRP, while Group 2 (G2) underwent resection of BRONJ but without the use of PRP. The treatment groups were evaluated after 14, 28, and 42 days. Clinical, microtomographic, microscopic, and immunohistochemical (IHC) evaluations were performed. Microtomography results revealed no significant difference between the groups (p <0.05) in any time period. Histomorphometric analysis showed increased bone formation over time for both groups (p < 0.001). G1 demonstrated a greater amount of new bone formation than G2 at 28 and 42 days (p < 0.001), with G1 presenting greater vascularization and a slightly higher VEGF expression. For both groups, RANKL/OPG expression levels were sufficient as a parameter for indicating the rate of bone remodeling in a previously treated area of osteonecrosis groups. Taken together, our findings indicated that the use of PRP improves the resolution process of BRONJ.

Refractory healing after surgical therapy of osteonecrosis of the jaw: associated risk factors in aged patients.

Purpose: Osteonecrosis of the jaw (ONJ), both medication-related and non medication-related, mainly occurs in aged patients. It needs surgical intervention. Refractory healing after an operation of ONJ can significantly lower the quality of life of elderly patients. The purpose of this study was to determine risk factors associated with refractory healing in aged patients. Patients and methods: We performed a retrospective study of ONJ in aged patients who underwent surgical treatments in a single institute during a 12-year period. Multiple logistic regression analysis was used to determine independent risk factors associated with refractory healing. Results: A total of 122 patients were included. Of them, 25 patients were identified as the refractory group and 97 patients as the control group. Diabetes mellitus (DM) (AOR=5.03, 95% CI: 1.74-14.52) and glucocorticoid administration (AOR=7.97, 95% CI: 2.52-25.23) were found to be significant risk factors for refractory healing of ONJ. Conclusion: DM and medication of glucocorticoid might be risk factors for refractory healing of ONJ.

Low-Intensity Pulsed Ultrasound Prevents Development of Bisphosphonate-Related Osteonecrosis of the Jaw-Like Pathophysiology in a Rat Model.

We developed a rat model of bisphosphonate-related osteonecrosis of the jaw (BRONJ) by removing a maxillary molar tooth (M1) from ovariectomized rats after treatment with alendronate. To mimic periodontitis, some of the rats were administered Porphyromonas gingivalis (p. gingivalis) at the M1 site every 2 to 3 d for 2 wk. Rats pretreated with alendronate plus p. gingivalis showed delayed healing of socket epithelia, periosteal reaction of alveolar bone formation and lower bone mineral density in the alveolus above adjacent M2 teeth. These abnormalities were prevented by tooth socket exposure to 20 min/d low-intensity pulsed ultrasound (LIPUS), which restored diminished expression of RANKL, Bcl-2, IL-6, Hsp70, NF-κB and TNF-α messenger ribonucleic acids in remote bone marrow, suggesting LIPUS prevented development of BRONJ-like pathophysiology in rat by inducing systemic responses for regeneration, in addition to accelerating local healing. Non-invasive treatment by LIPUS, as well as low-level laser therapy, may be useful for medication-related osteonecrosis of the jaw patients.

Medication-Related Osteonecrosis of the Jaws: Two Center Retrospective Cohort Studies.

This retrospective cohort study aims to describe characteristics of patients with MRONJ, to identify factors associated with MRONJ development, and to examine variables associated with favourable outcome. Totally 32 patients were followed and observed: 21 females and 11 males, in the age range 35-84 in the period from 2009 to 2018. Clinical, radiological examination (Orthopantomograph and CBCT) and biopsy were performed in order to achieve diagnosis. Demographic and clinical variables were taken into consideration: sex, age, primary disease, medication type, mode of delivery, anatomic location, drug treatment duration, timing of tooth extraction, chemotherapy, presence of bone metastasis, aetiology of MRONJ, disease stage, and treatment modality. MRONJ developed under osteoporosis and malignant disease in 11 and 21 patients, respectively. MRONJ development was triggered by tooth extraction or trauma in 30 out of 32 cases, whereas the two patients developed MRONJ spontaneously. Stages I, II, and III were confirmed in 5 (16%), 18 (58%), and 9 (28%) patients, respectively. Mandible was affected in 23 (72%) patients. MRONJ was treated in our department by conservative and surgical modality. In this study we found that 65% of all patients were classified in the cured/improvement group and 35% in the stable/progression group. The female gender, osteoporosis as primary disease, oral regime intake, shorter period on BPs, earlier stage of disease, and specific anatomic localisation (frontal and premolar maxilla) were factors associated with better response to therapy and favourable clinical outcome. Comprehensive treatment protocol and further randomized studies are necessary for further improvements.

Treatment of bisphosphonate-related osteonecrosis using platelet-rich plasma: microtomographic, microscopic, and immunohistochemical analyses

Abstract The present study aimed to investigate the use of platelet-rich plasma (PRP) on tooth extraction sites in rats treated with bisphosphonates. Thirty Albinus Wistar male rats were administered 0.035 mg/kg zoledronic acid intravenously for 8 weeks, divided into four administrations with a 2-week interval between each application, after which their upper right central incisors were extracted to induce the development of bisphosphonate-related osteonecrosis of the jaw (BRONJ). The samples were divided into the following two groups: Group 1 (G1) underwent marginal resection of BRONJ followed by the use of PRP, while Group 2 (G2) underwent resection of BRONJ but without the use of PRP. The treatment groups were evaluated after 14, 28, and 42 days. Clinical, microtomographic, microscopic, and immunohistochemical (IHC) evaluations were performed. Microtomography results revealed no significant difference between the groups (p <0.05) in any time period. Histomorphometric analysis showed increased bone formation over time for both groups (p < 0.001). G1 demonstrated a greater amount of new bone formation than G2 at 28 and 42 days (p < 0.001), with G1 presenting greater vascularization and a slightly higher VEGF expression. For both groups, RANKL/OPG expression levels were sufficient as a parameter for indicating the rate of bone remodeling in a previously treated area of osteonecrosis groups. Taken together, our findings indicated that the use of PRP improves the resolution process of BRONJ.

The rise and fall of the alveolar process: Dependency of teeth and metabolic aspects.

The alveolar bone has a unique capacity to follow the teeth's movements. It is formed around erupting teeth and their periodontal ligaments: the more the teeth have erupted, the larger the alveolar process. Throughout life the teeth erupt and migrate in an occlusal and mesial direction to compensate for attrition, an evolutionary trait. After tooth extraction, the alveolar process is resorbed to varying degrees. The mandibular alveolar bone mirrors skeletal bone condition. Due to fast bone turnover (which is the fastest in the whole skeleton), low bone mass and increased fracture risk may first be seen here. If a periapical radiograph of the mandibular premolars shows a dense trabeculation with well-mineralized trabeculae and small intertrabecular spaces, it is a reliable sign of normal skeletal bone density (BMD) and low skeletal fracture risk, whereas a sparse trabecular pattern indicates osteopenia and high fracture risk. The bone turnover rate in the mandible is twice that of the maxilla, and may, hypothetically, play a role in the development of osteonecrosis of the jaw (ONJ), which has been found mainly in the mandibular alveolar process?

Efficacy of bovine lactoferrin in the post-surgical treatment of patients suffering from bisphosphonate-related osteonecrosis of the jaws: an open-label study.

Osteonecrosis of the jaws is an emerging pathological condition characterized by un-exposure or exposure of the necrotic bone, independently from the etiology. This term is usually referred to medication-related osteonecrosis of the jaws due to severe adverse reaction to certain medicines, as bisphosphonates, used for the treatment of cancer and osteoporosis. The management of patients with Bisphosphonate-Related Osteonecrosis of the Jaws (BRONJ) remains challenging because surgical and medical interventions may not eradicate this pathology. The goal of treatment of patients at risk of developing BRONJ or of those who have active disease is the preservation of quality of life by controlling pain, managing infection, and preventing the development of new areas of necrosis. The treatment of osteonecrosis consists in the surgical removal of necrotic bone followed by antibiotic therapy and application of sterile greasy gauze until the wound closure. The classical medical treatment has been compared with the innovative one consisting in the application of sterile greasy gauze soaked with bovine lactoferrin (bLf) after surgery. Here, for the first time, bLf efficacy on wound repair in subjects suffering from BRONJ with the progressive destruction of bone in the mandible or maxilla has been demonstrated. The positive results consist in a significant shorter time of wound closure (1 or 2 weeks) compared to that observed with classical surgical treatment (2-3 months). These promising results are an interesting tool for the innovative treatment of this pathology and for increasing the quality of life of these patients.

Zoledronate Impairs Socket Healing after Extraction of Teeth with Experimental Periodontitis.

Osteonecrosis of the jaws (ONJ) is a rare but severe complication of antiresorptive medications, such as bisphosphonates, used in the treatment of bone malignancy or osteoporosis. Tooth extraction and dental disease have been strongly associated with ONJ development. Here, we investigated molecular and cellular markers of socket healing after extraction of healthy or teeth with experimental periodontitis (EP) in Wistar-Han rats treated with zoledronic acid (ZA). We included 4 experimental groups: vehicle-treated animals with extraction of healthy teeth or teeth with ligature-induced EP and ZA-treated animals with extraction of healthy teeth or teeth with EP. Animals were pretreated with vehicle or ZA for a week, and EP was induced. Four weeks later, the second maxillary molars were extracted; sockets were allowed to heal for 4 wk; animals were euthanized; and maxillae were isolated. Radiographically, extraction sockets in groups 1, 2, and 3 demonstrated normal healing. Contrary incomplete socket healing was noted after extraction of teeth with EP in ZA-treated rats of group 4. Histologically, persistent inflammation and extensive osteonecrosis were seen in group 4. Disorganization of the collagen network, collagen type III predominance, and lack of collagen fiber insertion in the necrotic bone were associated with impaired socket healing. Cells positive for MMP-9, MMP-13, and α-SMA expression were present at the areas of epithelial invagination and adjacent to osteonecrotic bone. Importantly, human biopsies from patients with ONJ showed similar findings. Our data emphasize the importance of dental disease and tooth extraction in ONJ pathogenesis and help delineate an altered profile in wound-healing markers during ONJ development.

Surgical treatment of stage 2 medication-related osteonecrosis of the jaw compared to osteomyelitis.

OBJECTIVE: To compare the characteristics and outcomes of patients who underwent surgical treatment for stage 2 medication-related osteonecrosis of the jaw (MRONJ) versus osteomyelitis. METHODS: This retrospective study compared the following variables in 73 patients with stage 2 MRONJ versus 89 patients with osteomyelitis: impaired wound healing after surgery, sex, age, the presence of actinomycosis, location of the jaw lesion, and involvement of the inferior alveolar nerve (IAN). RESULTS: There were significant differences between the groups in age, sex, rates of impaired wound healing, actinomycosis, and the location (anterior/posterior) of the lesion. Impaired wound healing after surgical treatment in the stage 2 MRONJ group was associated with patient age. All patients with impaired wound healing after the initial surgery recovered fully after reoperation. CONCLUSIONS: These findings for surgical treatment of stage 2 MRONJ may help clinicians plan surgical treatment of MRONJ.

Platelet rich fibrin in the management of medication-related osteonecrosis of the jaw: a clinical and histopathological evaluation.

Bisphosphonates are antiresorptive pharmacological agents used in the treatment of osteoporosis. Recently, osteonecrosis of the jaw has been recognized as a potential side effect in patients on long-term bisphosphonate therapy. This condition, popularly called bisphosphonate-related osteonecrosis of the jaw (BRONJ), has been rechristened as MRONJ (medication-related osteonecrosis of the jaw) to accommodate the increasing number of cases of osteonecrosis of jaws associated with various other antiresorptive and antigiogenic pharmacological therapies. The aim of the present study was to assess the outcome of using platelet-rich fibrin (PRF) for the treatment of MRONJ in a single study group. Twenty-three consecutive patients (15 females and 8 males; aged 52-73 years) with MRONJ were enrolled in this study. These patients presented a history of bisphosphonate medication of varying duration, presence of exposed bone in the maxillofacial region for more than eight weeks, and no history of radiation therapy to the jaws. These patients were managed by surgical curettage and application of platelet rich fibrin (PRF). The outcomes were assessed using clinical and histopathological methods. On the basis of the present findings, we can conclude that PRF can act as an effective barrier membrane between the alveolar bone and the oral cavity and may offer a fast, easy and effective alternative method for the closure of bone exposure in MRONJ patients.

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

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

Efeito da terapia de longa duração com ácido zoledrônico no osso esponjoso da mandíbula e fêmur de ratos Wistar / Effect of long-term zoledronic acid treatment on cancellous bone in the mandible and femur of Wistar rats

Os bisfosfonatos (BF) são amplamente utilizados no tratamento de doenças osteolíticas como metástases ósseas e osteoporose. A osteonecrose dos maxilares associada ao uso de BF (OMAB) é caracterizada pela presença de osso exposto ou que pode ser sondado através de uma fístula que persiste por mais de oito semanas em pacientes com história de terapia de BF e sem história de radioterapia na região de cabeça e pescoço e/ou sem doença metastática nos maxilares. A incidência de OMAB aumenta com a potência, duração do tratamento e dose de BF recebida. Até o presente momento, a fisiopatologia da OMAB não está clara, dificultando a prevenção e o tratamento. O objetivo deste estudo foi avaliar o efeito da administração de altas doses Ácido Zoledrônico (AZ) por período prolongado no osso esponjoso da mandíbula e da metáfise proximal do fêmur de ratos Wistar. Para relacionar as descobertas à fisiopatologia da OMAB, o regime de administração de BF de um modelo animal relevante desta lesão foi reproduzido. Seis animais receberam AZ (0,6 mg / kg) e seis receberam solução salina no mesmo volume (Controles). Os compostos foram administrados por via intraperitoneal em cinco doses a cada 28 dias. A eutanásia dos animais ocorreu após 150 dias de início da terapia. As hemimandíbulas e fêmures direitos foram escaneados usando Micro-tomografia computadorizada (Micro-CT) de alta resolução (14 m). Para a primeira análise realizada neste estudo, os dados morfométricos do osso esponjoso foram calculados na região do segundo e primeiro molar na mandíbula e na metáfise do fêmur usando CTAnalyzer (Bruker, Bélgica). Para a segunda análise, cinco amostras de hemimandíbulas de cada grupo foram cortadas em lâminas histológicas (5 m) e coradas com Hematoxilina e Eosina. Para comparar os parâmetros morfométricos na Micro-CT e histologia, as imagens de Micro-CT foram espacialmente alinhadas à histologia. Os dados morfométricos do osso alveolar foram calculados usando o software CTAnalyzer (Bruker, Bélgica) na região entre as raízes mesial e distal do primeiro molar. A densidade da área vascular (área vascular/área total; VA/TA) e os dados histomorfométricos ósseos foram estimados usando Axiovision na mesma região (entre as raízes mesial e distal do primeiro molar). Foi adotada significância estatística de 5% ( = 0,05). Os animais tratados com AZ apresentaram aumento significativo na porcentagem de volume ósseo (p <0,05) com trabéculas mais espessas, osso mais compacto com menor separação trabecular na mandíbula e no fêmur. Na mandíbula, o aumento da densidade óssea e diminuição da separação trabecular foram fortemente correlacionados com a diminuição da área vascular observada no grupo AZ (p <0,05). Em conclusão, o tratamento de longa duração com altas doses de AZ foi significativamente associado ao aumento na densidade óssea e à diminuição dos espaços medulares, canais nutritivos e vasculatura do osso alveolar. A análise com Micro-CT revelou alterações semelhantes na estrutura óssea tanto na mandíbula quanto no fêmur do grupo AZ.(AU)

Bisphosphonates (BFs) are widely used in the treatment of osteolytic diseases such as bone metastases and osteoporosis. The osteonecrosis of the jaws related to BF (ONB) is characterized by the presence of exposed bone or bone that can be probed through a fistula that persists for more than eight weeks in patients with a history of BF therapy and without history of head and neck radiotherapy and / or without metastatic disease in the jaws. The incidence of ONB increases with potency, duration of treatment and dose of BF received. Thus far, the pathophysiology of ONB is unclear, hampering prevention and treatment. The aim of this study was to objectively assess the effect of long-term high-dose Zoledronic Acid (ZA) on cancellous bone in the jaw and femur of Wistar rats. In order to link our findings to the physiopathology of ONB, the therapeutic regiment of a relevant ONB animal model was reproduced. Twelve Wistar rats were randomly divided in two groups: six received Zoledronic acid (ZA; 0.6 mg / kg) and six (Controls) received saline solution in the same volume. The compounds were administrated intraperitoneally in five doses each 28 days. The rats were killed after 150 days of the therapy onset. Mandibles and femurs were scanned using a high-resolution (14m) micro-computerized tomography (Micro-CT). For the first analysis carried in this study, cancellous bone morphometric data were calculates in the region of the second and first molar in the mandible and in the proximal femur using CTAnalyzer (Bruker, Belgium). For the second analysis five samples were cut into histological slices (5m) and stained with Hematoxylin and Eosin. In order to compare the same morphological structures in Micro-CT and histology, the Micro-CT images were aligned to histology. Alveolar bone morphometric data (Micro-CT) was calculated using CTAnalyzer (Bruker, Belgium) in the region between the mesial and distal roots of the first molar. Blood vessels density and bone histomorphometric data were calculated using Axiovision (Carl Zeiss, Germany) in the same region used for Micro-CT evaluation. Statistical significance of 5% (=0.05) was adopted. ZA treated rats presented significant increase in the percentage of bone volume (p<0.05) with thicker trabeculae and more compact bone with smaller marrow spaces in the mandible and femur. In the mandible, the increase in bone density and decrease of marrow spaces size was strongly correlated with the decrease in the vascular area noticed in the ZA group (p<0.05). In conclusion, long-term high-dose ZA treatment was significant associated with the increase of bone density and the diminution of medullary spaces and nutritive canals size as well as decrease in vascularity of the alveolar bone. Micro-CT investigation showed similar changes in bone structure in the mandible and femur in the ZA group.(AU)