Bisphosphonate-related osteonecrosis of the jaw: an overview

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.

A large animal model of periodontal defects in bisphosphonate-related osteonecrosis of the jaw: a comparison of clinical and radiological findings

PURPOSE

The objective of this study was to demonstrate the suitability of cone-beam computed tomography (CBCT) for in vivo research in periodontology, with implications for oral implantology, facial traumatology, and all disciplines involved in treating patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ).

METHODS

Halves of the jaws of 9 Swiss mountain sheep, assigned to a control group (n=3), an osteoporosis group (n=3) and a zoledronate-exposed group (n=3), were examined. Clinical and radiological evaluations were conducted using CBCT imaging to assess whether periodontitis and bone defects were observed to a significant extent after surgical tooth extraction.

RESULTS

In contrast to the control and osteoporosis groups, the zoledronate group exhibited significant residual bone defects following tooth extraction (P<0.05). CBCT more objectively revealed these effects and enabled a numerical evaluation (in mm3).

CONCLUSIONS

Evaluating residual defects in bone blocks from sheep using CBCT analysis was found to be as effective as a clinical examination conducted by specialists in oral and maxillofacial surgery. The strong correlation between radiological findings and clinical conditions suggests that CBCT may become increasingly important in the future, particularly in periodontological research related to BRONJ.

Does resveratrol favor peri-implant bone repair in rats with ovariectomy-induced osteoporosis? Gene expression, counter-torque and micro-CT analysis

This study investigated the influence of resveratrol on peri-implant repair and its effects on bone-related markers in ovariectomy-induced osteoporosis in rats. Animals were divided into: OVX+PLAC (n = 10): ovariectomized animals treated with placebo; OVX+RESV (n = 10): OVX treated with resveratrol; OVX+PLAC+ZOL (n = 10): OVX treated with PLAC and zoledronate; OVX+RESV+ZOL (n = 10): OVX treated with RESV and ZOL; and SHOVX+PLAC (n = 10): sham ovariectomy treated with PLAC. RESV and PLAC were administrated after ovariectomy and ZOL after six weeks after OVX, until the end of experiment. One implant was inserted in each tibiae of animals 18 weeks after ovariectomy. After 4 weeks, one implant was removed for counter-torque, and peri-implant tissue was collected for mRNA quantification of several osteogenic markers by PCR. The other tibia was submitted to micro-computed tomography analysis. Reduced counter-torque values, bone-implant contact (BIC) and bone volume fraction (BV/TV), and higher bone porosity (BP) were detected in OVX+PLAC group when compared to SHOVX+PLAC (p < 0.05). OVX+RESV rats presented lower BIC, BV/TV, and trabecular number (Tb.N), and augmented BP and trabecular spacing (Tb.Sp) when compared to SHOVX+PLAC (p < 0.05). Higher Tb.N and connectivity density (Conn.Dn) and reduced Tb.Sp were observed in OVX rats treated with ZOL, independently of RESV, when compared to OVX+PLAC and OVX+RESV groups (p < 0.05), whereas the combination ZOL+RESV promoted lower BP when compared to OVT+PLAC and OVX+RESV (p < 0.05). Gene expression was not influenced by RESV (p > 0.05), whereas ZOL promoted up-regulation of BMP-2 (p<0.05). RESV did not improve peri-implant bone repair in rats with ovariectomy-induced osteoporosis.

Quantitative Real-Time Gene Profiling of Human Alveolar Osteoblasts Using a One-Step System

The use of quantitative real-time reverse transcriptase PCR (qRT²-PCR) for the identification of differentially regulated genes is a powerful technology. The protocol presented here uses qRT²-PCR gene arrays to investigate the regulation of 84 angiogenic related genes in human primary alveolar osteoblasts following treatment with the bisphosphonate, zoledronic acid, and geranylgeraniol (GGOH). GGOH has potential as a therapeutic agent for medication-related osteonecrosis of the jaw, a serious side effect resulting from treatment for metastatic cancer (Zafar S, Coates DE, Cullinan MP, Drummond BK, Milne T, Seymour GJ. J Oral Pathol Med 43:711-721, 2014). The isolation of the primary osteoblast cells follows the methods described by Dillon et al. (Method Mol Biol 816:3-18, 2012) with a new RNA extraction technique described fully. The method highlights the importance of obtaining high-quality RNA which is DNA-free. Relative levels of gene expression are normalized against selected reference genes (HKG) and a number of examples of how fold regulation (2^-ΔΔCq) and gene expression level (2^-ΔCq) data can be presented are given.

Bone-on-a-chip platforms and integrated biosensors: Towards advanced in vitro bone models with real-time biosensing

Bone diseases, such as osteoporosis and bone defects, often lead to structural and functional deformities of the patient's body. Understanding the complicated pathophysiology and finding new drugs for bone diseases are in dire need but challenging with the conventional cell and animal models. Bone-on-a-chip (BoC) models recapitulate key features of bone at an unprecedented level and can potentially shift the paradigm of future bone research and therapeutic development. Nevertheless, current BoC models predominantly rely on off-chip analysis which provides only endpoint measurements. To this end, integrating biosensors within the BoC can provide non-invasive, continuous monitoring of the experiment progression, significantly facilitating bone research. This review aims to summarize research progress in BoC and biosensor integrations and share perspectives on this exciting but rudimentary research area. We first introduce the research progress of BoC models in the study of bone remodeling and bone diseases, respectively. We then summarize the need for BoC characterization and reported works on biosensor integration in organ chips. Finally, we discuss the limitations and future directions of BoC models and biosensor integrations as next-generation technologies for bone research.

The Use of Hydroxyapatite Loaded with Doxycycline (HADOX) in Dentoalveolar Surgery as a Risk-Reduction Therapeutic Protocol in Subjects Treated with Different Bisphosphonate Dosages

Medication-related osteonecrosis of the jaw (MRONJ) is considered as a severe adverse side effect of specific drugs such as anti-resorptive and anti-angiogenic medications. Evidence suggests that MRONJ is linked to invasive dental procedures, mainly dentoalveolar surgery. Several preventive strategies to minimize the risk of developing MRONJ have been investigated. However, no investigation has been attempted to evaluate the therapeutic effect of local drug-delivery technology as a preventive strategy protocol. The aim of this study is to evaluate the efficacy of hydroxyapatite-containing doxycycline (HADOX) in rats with high-risk MRONJ development. All the rats used in this study were divided into seven groups. Six groups of rats out of seven were exposed to two different doses of antiresorptive drug therapy for four weeks before undergoing an upper incisor extraction. After 28 days, all the animals were euthanized, and the bone blocks were processed for histological and histomorphometrical evaluation. The histomorphometric analysis confirmed that newly formed bone (NFB) was present in all groups, with significant differences. NFB in the HADOX group treated with zoledronic acid at 4% showed (28.38; C.I. 22.29-34.48), which represents a significant increase compared to HA (15.69; C.I. 4.89-26.48) (p = 0.02). A similar pattern was observed in the HADOX group treated with zoledronic acid 8% ZA treatment (p = 0.001). Conclusions: HADOX did not inhibit any bone repair and reduced early inflammatory response. Hence, HADOX could promote bone healing in patients undergoing antiresorptive drug therapy.

Efficacy of Adjunctive Photobiomodulation in the Management of Medication-Related Osteonecrosis of the Jaw: A Systematic Review

Background: Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse medication response that manifests as progressive bone necrosis in the craniofacial area. There is still no clear treatment protocol for the management of MRONJ. The purpose of this study was to conduct a systematic review to assess the efficacy of photobiomodulation (PBM) as an adjunct to MRONJ therapy. Methods: In line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, a literature search was performed on PubMed/MEDLINE, Scopus, Web of Science, and Cochrane databases. Two examiners examined eligibility and risk of bias separately before extracting data. Results: Two hundred sixty-nine articles were found through electronic search, out of which only 11 met the inclusion criteria and were included in qualitative synthesis (9 retrospectives, 1 prospective, and 1 case series). A total number of 759 patients and a mean age ranging from 54 to 74 years were reviewed. Females were the most frequent gender in all of the selected studies (72% females to 28% males), and the most frequent stage in the studies mentioned above was stage II (66%). Most of the studies had shown a significant improvement when PBM was used as an adjunctive treatment. Conclusions: Based on the results of this study, PBM as an adjuvant therapy can significantly improve the outcomes of each treatment plan. However, surgical intervention for the complete healing of the lesions is suggested.

Contribution of Antiangiogenic Agents to the Risk of Medication-related Osteonecrosis of the Jaw in Combination with Antiresorptive Agents: Preliminary Results in a Comparative Prospective Report of 59 Oncologic Cases

AIM

The aim of this preliminary study was to evaluate in an oncological population the association risk of antiangiogenic (AA) agents to antiresorptive (AR) agents on the incidence and the severity of medication-related osteonecrosis of the jaw (MRONJ).

MATERIALS AND METHODS

In this prospective study, we reviewed the medical records and clinical variables of 59 consecutive oncologic patients who developed MRONJ. For all patients, we retrieved the following variables: age, gender, alcohol and tobacco use, type of cancer, use of corticosteroids for >3 months, history of diabetes, MRONJ staging, combination of AR and AA agents, dental history (surgery, prosthesis) or spontaneous, site of MRONJ, delay between AR and AA first intake, and MRONJ development. Patients were divided into two groups according to drugs therapy they underwent: group 1 (G1) including patients treated with AR agents alone and group 2 (G2) including patients receiving antiresorptive-antiangiogenic drugs (AR+AA). The degree and the therapeutical success were defined as primary outcomes and the number, the localization, and the delay in onset of the lesions as secondary outcomes. In order to identify predictive factors of osteonecrosis-free interval time, univariate and multivariate Cox regression was performed. Statistical tests were carried out using the IBM^® SPSS^® Statistics software. All reported P-values are two-tailed and were considered to be significant when less than 0.05.

RESULTS

Among the 47 patients who received AR agent alone (group 1), the mean treatment duration before diagnosis of MRONJ was 39.2 months. In the second group (n = 12), patients developed MRONJ with a comparable mean time of 55 months (P = 0.16). According to the staging of MRONJ at the time of diagnosis, no significant difference (P = 0.736) was observed between the two groups. Moreover, the treatment applied was not statistically different in both the groups and was successful in 36.17% of the patients in group 1 and 58.33% of the patients in group 2. No statistically difference was reported in both the groups (P = 0.16). After statistical analysis, no significant difference in terms of MRONJ localization (P = 0.13) was observed. Finally, the incidence of spontaneous MRONJ was comparable in both the groups. Statistical analysis revealed that total time of treatment was the only factor associated with poor osteonecrosis-free interval time (hazard ratio 0.99; P = 0.001). Interestingly, the combination of an AA and AR agent was not a significant predictor factor of the interval time before the diagnosis of osteonecrosis. Additionally, corticosteroid use, diabetes mellitus, and dental consultation before treatment were not statistically related to poorer osteonecrosis-free interval time rates.

CONCLUSION

In our preliminary study, neither the mean treatment time duration before the diagnosis of MRONJ nor the dose delivered was different in both the groups (AR vs. AR+AA). Moreover, no significant difference was observed between both the groups regarding the localization and the staging of MRONJ at the time of diagnosis. Interestingly, our results demonstrated that the risk of spontaneous MRONJ is statistically comparable in the AR and AR-AA groups. Additionally, the addition of an AA agent did not influence the treatment applied in the two groups of patients.

Medication-related osteonecrosis of the jaw (MRONJ) and eNOS Polymorphisms in multiple myeloma patients: a single center experience

Background

Multiple myeloma (MM) constitutes approximately 10% of hematological malignancies. Bisphosphonates have established themselves in solid organ metastasis and multiple myeloma lytic bone lesions by inhibiting osteoclast activation. Medication-related osteonecrosis of the jaw (MRONJ) emerges as an important complication. Investigating host-based factors, and developing personal risk factors gain importance in the development mechanism of MRONJ. We aimed to reveal the different genotype polymorphisms, and clinical effects of eNOS in patients with a diagnosis of MRONJ in MM patients.

Methods

Medical records and blood samples were collected from 60 MRONJ patients with MM and 60 healthy controls. Inclusion criteria was having an exposed maxillofacial bone for more than eight weeks, a history of bisphosphonates, and no history of radiation therapy for the jaws. eNOS G894T and intron 4 VNTR were calculated by polymerase chain reaction and/or restriction fragment length polymorphism.

Results

eNOS G894T and VNTR genotypes and alleles were compared statistically with the healthy control group. There was no significant difference between the two groups. In comparison between G894T and clinical parameters, aphthous stomatitis was more common in TT genotype, while DMFT > 3 was more common in TG-GG genotype (p = 0.035, 0.023).

Conclusions

eNOS induces osteogenesis in bone metabolism, with its regulatory effects on bone remodeling and also NO induced angiogenesis takes place indirectly with its protective effect on endothelial functions. We see that these polymorphisms affecting the entire process of bone remodeling and angiogenesis, especially mucosal damage, which is the triggering factor of MRONJ pathology, have been revealed in the MM patient group. Considering the MRONJ initiating factors, it is necessary to emphasize the importance of our study results. It should be seen as an important step for new studies towards MRONJ and its treatment.

Mandibular Reconstruction with Free Fibula Flap for Medication-related Osteonecrosis of the Jaw in Patients with Multiple Myeloma

While bisphosphonates are the cornerstone for management of multiple myeloma, they are associated with medication-related osteonecrosis of the jaw (MRONJ). There are many controversies in the management of MRONJ in this patient population. In this article, we describe a representative case and, along with a literature review, we report the outcomes of our 3 cases with multiple myeloma who underwent mandible reconstruction with vascularized fibula bone grafts after segmental mandible resection for Stage 3 MRONJ over a 3-year period. All patients were male with a mean age of 59 years. All patients had undergone therapy with bisphosphonates and had no other identifiable cause of mandible osteonecrosis. All patients had pathologic mandible fractures associated with intraoral fistulae and exposed bone. Nonsurgical management was attempted in all patients. One patient also underwent debridement of the mandible without resolution of the disease. Mandible reconstruction with an osteocutaneous free fibula flap after segmental mandible resection was performed in all 3 cases without major complications or donor site morbidity. Different bacteria were isolated from the intraoperative tissue cultures in all cases. Computed tomographic imaging revealed bony union without hardware complications in all cases. Mean follow-up was 28 months. In conclusion, we demonstrated that patients with multiple myeloma and advanced MRONJ lesions of the mandible can be managed successfully and safely by segmental resection and reconstruction with vascularized fibula bone graft.

Pathogenesis and multidisciplinary management of medication-related osteonecrosis of the jaw

Medication-related osteonecrosis of the jaw (MRONJ) is a serious side effect of bone-modifying agents and inhibits angiogenesis agents. Although the pathogenesis of MRONJ is not entirely clear, multiple factors may be involved in specific microenvironments. The TGF-β1 signalling pathway may have a key role in the development of MRONJ. According to the clinical stage, multiple variables should be considered when selecting the most appropriate treatment. Therefore, the prevention and management of treatment of MRONJ should be conducted in patient-centred multidisciplinary team collaborative networks with oncologists, dentists and dental specialists. This would comprise a closed responsibility treatment loop with all benefits directed to the patient. Thus, in the present review, we aimed to summarise the pathogenesis, risk factors, imaging features, clinical staging, therapeutic methods, prevention and treatment strategies associated with MRONJ, which may provide a reference that can inform preventive strategies and improve the quality of life for patients in the future.

Borate bioactive glass prevents zoledronate-induced osteonecrosis of the jaw by restoring osteogenesis and angiogenesis

OBJECTIVES

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a severe complication of systemic nitrogen-containing bisphosphonate (N-BP) administration, which leads to osteonecrosis, pain, and infection. Despite much effort, effective remedies are yet to be established. This study aimed to investigate potential recovery effect of borate bioactive glass (BBG) in vitro and in vivo.

METHODS

The effect of BBG on zoledronate-treated bone marrow mesenchymal cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) was explored by cell counting kit-8, EdU assay, flow cytometry, alkaline phosphatase staining, alizarin red staining, angiogenesis experiment, and real-time quantitative polymerase chain reaction. The preventive effect of BBG on zoledronate-induced osteonecrosis of the jaw in rat model was examined by micro-CT, HE staining, and immunohistochemistry.

RESULTS

Exposure of BBG to BMSCs and HUVECs increased cell proliferation and restored their osteogenesis and angiogenesis potential in vitro. The BRONJ lesions were satisfactorily repaired and bone mineral density, bone volume/tissue volume, trabecula number, OCN-positive cells, and CD31-positive cells were increased in the BBG-treated groups compared with saline-treated groups.

CONCLUSIONS

Exposure of BMSCs and HUVECs to BBG restores osteogenesis and angiogenesis inhibited by zoledronate. BBG successfully restores extraction socket healing of BRONJ in rat model.

Targeting prenylation inhibition through the mevalonate pathway

Protein prenylation is a critical mediator in several diseases including cancer and acquired immunodeficiency syndrome (AIDS). Therapeutic intervention has focused primarily on directly targeting the prenyltransferase enzymes, FTase and GGTase I and II. To date, several drugs have advanced to clinical trials and while promising, they have yet to gain approval in a medical setting due to off-target effects and compensatory mechanisms activated by the body which results in drug resistance. While the development of dual inhibitors has mitigated undesirable side effects, potency remains sub-optimal for clinical development. An alternative approach involves antagonizing the upstream mevalonate pathway enzymes, FPPS and GGPPS, which mediate prenylation as well as cholesterol synthesis. The development of these inhibitors presents novel opportunities for dual inhibition of cancer-driven prenylation as well as cholesterol accumulation. Herein, we highlight progress towards the development of inhibitors against the prenylation machinery.

Investigation of Sustained BMP Delivery in the Prevention of Medication-Related Osteonecrosis of the Jaw (MRONJ) in a Rat Model

Medication-related osteonecrosis of the jaw (MRONJ) poses an ongoing challenge for clinicians and researchers. Currently, there is a lack of preventative measures available for at-risk patients undergoing tooth extractions, especially those with prior bisphosphonate treatment due to osteoporosis or bone metastasis diagnoses. Here, these issues are addressed using a preventative tissue engineering strategy against MRONJ development. This study evaluates the efficacy of a poly(ethylene glycol)-heparin hydrogel as a tool for the delivery of arginylglycylaspartic acid (RGD) and recombinant human bone morphogenic protein-2 (rhBMP-2). Three groups of skeletally mature rats each receive two doses of intravenous zoledronic acid prior to surgery and undergo extraction of the right first mandibular molar with gingival closure. Experimental groups either have the sockets left empty, filled with hydrogel minus rhBMP-2, or filled with hydrogel plus rhBMP-2. Eight weeks postoperatively specimens are analyzed using radiological, histological, and scanning electron microscopy (SEM) techniques. µCT analysis shows increased bone formation with hydrogel/rhBMP-2 delivery compared to the empty socket. Hydrogel-treated groups display increased presence of osteocytes and increased osteoclastic action compared to the empty sockets. These results represent the first step toward improved delivery of rhBMP-2 and a potential MRONJ preventative for patients undergoing bisphosphonate treatment.

Bone remodeling-inspired dual delivery electrospun nanofibers for promoting bone regeneration

Developing a highly bioactive bone tissue engineering scaffold that can modulate the bone remodeling process for promoting bone regeneration is a great challenge. In order to tackle this issue, inspired by the balance between bone resorption and formation in the bone remodeling process, here we developed a mesoporous silicate nanoparticle (MSN)-based electrospun polycaprolactone (PCL)/gelatin nanofibrous scaffold to achieve dual delivery of alendronate (ALN) and silicate for a synergetic effect in modulating bone remodeling, where ALN inhibited the bone-resorbing process via preventing guanosine triphosphate-related protein expression, and silicate promoted the bone-forming process via improving vascularization and bone calcification. The scaffold was successfully prepared by encapsulation of ALN into MSNs (ALN@MSNs) and co-electrospinning of an acetic acid-mediated PCL/gelatin homogeneous solution with well-dispersed ALN@MSNs. The results of ALN and Si element release profiles indicated that the ALN@MSN-loaded nanofibers achieved dual release of ALN and silicate (produced due to the hydrolysis of MSNs) simultaneously. The bone repair data from a rat critical-sized cranial defect model revealed that the developed strategy accelerated the healing time from 12 weeks to 4 weeks, almost three times faster, while the other nanofiber groups only had limited bone regeneration at 4 weeks. In addition, we used interactive double-factor analysis of variance for the data of bone volume and maturity to evaluate the synergetic effect of ALN and silicate in promoting bone regeneration, and the result clearly proved our original design and hypothesis. In summary, the presented bone remodeling-inspired electrospun nanofibers with dual delivery of ALN and silicate may be highly promising for bone repair in the clinic.

Clinical characteristics and recurrence-related factors of medication-related osteonecrosis of the jaw

OBJECTIVES

The purpose of this study was to investigate the demographic and clinical characteristics of patients with medication-related osteonecrosis of the jaw (MRONJ) and to elucidate factors affecting recurrence in surgical treatment.

MATERIALS AND METHODS

A total of 51 patients who were diagnosed with MRONJ were analyzed according to demographic and clinical features and treatment results through a retrospective chart review from 2013 to 2017 in the Department of Oral and Maxillofacial Surgery, Korea University Anam Hospital, Seoul in Korea.

RESULTS

Alendronate composed the majority of medication doses (55.6%), followed by ibandronate (20.0%), risedronate (15.6%), and zoledronate (6.7%). Forty patients (88.9%) were given oral medication, and five patients (11.1%) were intravenously treated, and the mean duration of medication use was 61.1±42.9 months. A total of 10 patients (22.2%) had a drug holiday before MRONJ-induced dental treatment lasting an average of 6.8±7.0 months. MRONJ occurred 2.7 times more in the mandible, with 41 cases (73.2%) occurring in the mandible and 15 cases (26.8%) occurring in the maxilla, and the prevalence of affected posterior parts (premolar-molar) was six times greater than that of the anterior parts (incisor-canine) (48 cases vs 8 cases, 85.7% vs 14.3%). The most common dental cause of MRONJ was tooth extraction (69.6%). Regarding recurrence, there was no statistical difference in recurrence rate according to either site or stage. However, recurrence occurred in 4 out of 34 cases (11.8%) in the primary closure group and 9 out of 20 cases (45.0%) in the secondary healing group, and there was a statistical difference with respect to closure technique.

CONCLUSION

The identified risk factors in patients taking bone resorption inhibitors can aid dental clinicians in ensuring prevention and proper treatment of MRONJ.

Zoledronic acid increases the prevalence of medication-related osteonecrosis of the jaw in a dose dependent manner in rice rats (Oryzomys palustris) with localized periodontitis

OBJECTIVE

Investigate role of dose/duration of zoledronic acid (ZOL), a powerful anti-resorptive (pAR), on prevalence of medication-related osteonecrosis of the jaw (MRONJ) in rice rats (Oryzomys palustris), a species with natural susceptibility to food impaction-induced localized periodontitis (FILP). We hypothesize that ZOL induces MRONJ lesions in rice rats with FILP, and that the prevalence of MRONJ rises with increasing dose and duration of ZOL treatment.

METHODS

We performed a toxicology experiment with clinically-relevant doses of ZOL in female rats (N=230) fed standard (STD) rodent chow. At age 4weeks (baseline), 12 rats were necropsied. The rest were randomized into five groups that began to receive 0, 8, 20, 50 or 125μg/kg ZOL IV/q 4weeks. After 12, 18, 24 and 30weeks, subgroups (N=9-16) from each of the dose groups were necropsied. High-resolution macroscopic photos of all jaw quadrants were given a gross quadrant grade (GQG) (0-4 or MRONJ) that classified FILP lesion severity and determined presence of gross MRONJ. Quadrants with GQG≥1 were examined histopathologically. Logistic regression analysis (ZOL dose/duration) of MRONJ prevalence was completed.

RESULTS

We found: 1) 75% of 0μg/kg ZOL rats developed FILP lesions; 2) baseline rats and rats treated with 0μg/kg ZOL had no MRONJ; 3) 29 gross MRONJ cases were identified; 4) all gross MRONJ cases were confirmed histopathologically by the observation of exposed necrotic bone, and 53 new cases were discovered (total=82); 5) ZOL dose (P<0.001), but not duration (P=0.326), was a significant predictor of MRONJ prevalence; 6) 13% prevalence of gross MRONJ among all rats, with 22% prevalence among rats exposed to ZOL oncologic doses (20-125μg/kg); 7) 38% prevalence of histopathologic MRONJ among all rats, with 73% prevalence among rats exposed to ZOL oncologic doses.

CONCLUSIONS

This is the first experiment to show a dose response relationship between clinically relevant doses of ZOL and MRONJ prevalence.

Quantitative Real-Time Gene Profiling of Human Alveolar Osteoblasts

The use of quantitative real-time reverse transcriptase PCR (qRT²-PCR) for the identification of differentially regulated genes is a powerful technology. The protocol presented here uses qRT²-PCR gene arrays to investigate the regulation of 84 angiogenic related genes in human primary alveolar osteoblasts following treatment with the bisphosphonate, zoledronic acid (ZA), and geranylgeraniol (GGOH). GGOH has potential as a therapeutic agent for Bisphosphate-Related Osteonecrosis of the Jaw (BRONJ), a serious side-effect resulting from the treatment for metastatic cancer (Zafar et al., J Oral Pathol Med 43:711-721, 2014; Ruggiero, Ann NY Acad Sci 1218:38-46, 2011). The isolation of the primary osteoblast cells follows the methods previously described (Dillon et al., Methods Mol Biol 816:3-18, 2012) with a new RNA extraction technique described fully. The method highlights the importance of obtaining high-quality RNA which is DNA-free. Relative levels of gene expression are normalized against selected housekeeping genes (HKG) and a number of examples of how fold regulation (2^-∆∆Cq) and gene expression level (2^-∆Cq) data can be presented are given.

Hydrogen Sulfide: A Worthwhile Tool in the Design of New Multitarget Drugs

H₂S is a gaseous molecule able to trigger a plethora of central physiological and pharmacological effects as antioxidant, pro- and anti-inflammatory, pro- and anti-nociceptive, neuromodulator, and cytoprotective. The polypharmacology of H₂S depends on the wide variety of targets implicated, but, despite the efforts, the mechanisms of action that should clarify its activity are still not completely unrevealed. Nevertheless, many attempts to exploit the multifaceted profile of this molecule have already been accomplished and many chemical entities containing an H₂S-releasing pharmacophore have been synthetized. Here we discuss recent investigations on multitarget molecules able to release H₂S, with a particular focus on the combinations of "native drug" with moieties structurally able to release H₂S and their applications as therapeutic tools in bone disease, gastrointestinal system and neurodegenerative disorders.

Managing bisphosphonate-related osteonecrosis of the jaws with xenografts: a case report

It is possible to manage large bone destruction induced by BRONJ using xenograft grafting to promote a bone formation.

Medication-related osteonecrosis of the jaw. Introduction of a new modified experimental model

PURPOSE

To evaluate a modified experimental model for medication-related osteonecrosis of the jaw (MRONJ) through the upper right central incisor extraction followed by intravenous bisphosphonate administration.

METHODS

Forty five rats underwent the upper right central incisor tooth extraction were divided in 2 groups: Group I - experimental group, 30 rats received an intravenous administration protocol of zoledronic acid 35μg/kg into the tail vein every two weeks, totalizing four administrations, during eight weeks of administration, previously the extraction, and Group II - control group, 15 rats didn't received any medication before extraction. The groups were subdivided in postoperative periods: 14/28/42 days. Clinical analysis and microtomography were performed to verify the presence of osteonecrosis. In addition, descritive histological analysis of hematoxylin-eosin stained sections was performed to evaluate the presence of osteonecrosis or necrotic foci.

RESULTS

Twelve (40%) rats, from experimental group, showed clinical signs of MRONJ (p=0.005), however, all samples showed imaginologic findings like osteolysis and loss of integrity of the cellular walls (p≤0.001). Microscopic evaluation revealed osteonecrosis areas with microbial colonies and inflammatory infiltrate (p≤0.001). In the control group, all animals presented the chronology of a normal wound healing.

CONCLUSIONS

The presence of medication-related osteonecrosis of the jaw after maxillary central incisor extraction in rats. This new experimental model may be considered an option for the study of MRONJ.

Osteonecrosis

Younger patients are affected more often by osteonecrosis than by osteoarthritis, and osteonecrosis has significantly greater long-term morbidity.

Corticosteroids are the most common cause of nontraumatic osteonecrosis.

The femoral head is the most common site of osteonecrosis.

In rare instances, osteonecrosis of the jaw has been associated with bisphosphonate exposure. This phenomenon is more common with repeated intravenous infusions of bisphosphonates.

Case reports of osteonecrosis of the jaw in association with other medications, such as denosumab, have been reported.

The final common pathway in the pathogenesis of osteonecrosis is disruption of blood supply to a segment of bone.

Abnormalities in lipid metabolism, bone homeostasis, regulation of apoptosis, coagulopathies, innate immunity, and oxidative stress may play a role in the pathogenesis of osteonecrosis.

Epigenetics may alter the predisposition to develop osteonecrosis.

MRI is currently the optimal test for early diagnosis and identification of the extent of osteonecrosis.

Nonsurgical treatment of osteonecrosis does not change the natural history of the disease.

Although surgical treatment of femoral head osteonecrosis has many variations, most symptomatic patients eventually require total hip arthroplasty.

Knowledge of risk factors and early detection are crucial to the successful management of osteonecrosis.

Because of the lack of successful treatment options, new modes of management focus on the prevention of osteonecrosis.

Microscopic Evaluation of the Effect of Oral Microbiota on the Development of Bisphosphonate-Related Osteonecrosis of the Jaws in Rats

Objectives

Osteonecrosis of the jaws is a side effect associated with the use of bisphosphonates. Using histologic analysis, this study aimed to evaluate the influence of microbial colonies in the development of osteonecrosis in the jaws of rats subjected to nitrogenous and non-nitrogenous bisphosphonates, undergoing surgical procedures.

Material and Methods

Thirty-four rats (Rattus norvegicus, Wistar strain) were allocated randomly into three groups: 12 animals treated with zoledronic acid; 12 animals treated with clodronate; and 10 animals treated with saline. Sixty days after the start of treatment, the animals underwent three extractions of the upper right molars. After 120 days of drug administration, the rats were killed. Histologic analysis was performed on specimens stained with hematoxylin and eosin by the technique of manual counting points using Image-Pro Plus software on images of the right hemimaxilla.

Results

Osteonecrosis was induced in the test groups. There was no statistically significant association between the presence of microbial colonies and the presence of non-vital bone (Kruskal-Wallis, P > 0.05).

Conclusions

Use of zoledronic acid was associated with non-vital bone and the results suggested that the presence of microbial colonies does not lead to osteonecrosis.

Surgical management of bisphosphonate-related osteonecrosis of the jaws: literature review

PURPOSE

Surgical management of bisphosphonate-related osteonecrosis of the jaws (BRONJ) has been performed in an attempt to increase healing rates of the affected cases. This literature review aimed to identify clinical studies of surgical management of bisphosphonate-related osteonecrosis of the jaws (BRONJ) in order to assess their surgical treatment modalities, outcome and the follow-up.

METHODS

A search in the PubMed (Medline) database using specific terms and/or phrases as "bisphosphonate-related osteonecrosis" or "jaw osteonecrosis", and "surgical treatment" or "surgical management" was conducted in order to identify clinical trials and cases of surgical treatment of BRONJ. The review search covered the time period from 2004 to 2014. All studies identified in the search were selected according to the inclusion criteria. Relevant information was recorded according to the following items: author, year, number of patients, BRONJ clinical stage, surgical treatment modality, clinical success, and follow-up.

RESULTS

The initial database search yielded 345 titles. After filtering, 67 abstracts were selected culminating in 67 full text articles. A variety of surgical approach was found in this review: debridement, sequestrectomy bone resection, and bone reconstruction. Adjunctive therapies included hyperbaric oxygen, laser therapy, growth factors, and ozone.

CONCLUSION

Although there are many indexed studies about BRONJ, well-documented reports concerning surgical therapeutically techniques are scarce, resulting from a lack of well-established protocols. Considerable differences were found regarding sample size, surgical treatment modalities and outcomes. Clinical studies with larger number of patients and longer follow-up are required to provide best information for each surgical treatment modality and its outcomes.

Surgical management of bisphosphonate-related osteonecrosis of the jaw stages II and III

OBJECTIVE

The value of surgery in advanced stages of bisphosphonate-related osteonecrosis of the jaw (BRONJ) is still controversial. Hence, we evaluated the effect of surgical therapy in BRONJ stages II and III in combination with a standardized perioperative adjuvant treatment.

STUDY DESIGN

We included 39 patients who presented with BRONJ in a total of 47 locations and stages II (n = 23) and III (n = 24). All patients had exclusively received a monthly intravenous application of zoledronic acid. Surgical therapy consisted of complete removal of the necrotic jaw, accompanied by a standardized perioperative adjuvant treatment including intravenous antibiotic prophylaxis, gastric feeding, and an antimicrobiologic mouth rinsing.

RESULTS

Overall, 35 (74.5%) of the 47 BRONJ sites were treated successfully, with success defined as complete mucosal healing of the exposed jaw (n = 24) or as relative healing when surgical therapy downscaled BRONJ II or III to asymptomatic BRONJ stage I (n = 11). Interestingly, perioperative adjuvant treatment or bisphosphonate therapy parameters showed no statistical effect on the treatment outcome.

CONCLUSIONS

The results of the present study prove the effectiveness of surgical therapy for BRONJ stage II or III.

Dose-dependent inhibitory effects of zoledronic acid on osteoblast viability and function in vitro

Zoledronic acid (ZA), which is one of the most potent and efficacious bisphosphonates, has been commonly used in clinical practice for the treatment of various bone disorders. The extensive use of ZA has been associated with increasing occurrence of jaw complications, now known as bisphosphonate-associated osteonecrosis of the jaw (BRONJ). However, the mechanism underlying BRONJ remains to be fully elucidated. The aim of the present study was to investigate the effects of different concentrations of ZA on the MC3T3-E1 murine preosteoblast cell line cells and examine the possible pathogenesis of BRONJ. In the present study, the effect of ZA on the viability, apoptosis, differentiation and maturation of MC3T3-E1 cells, as well as its relevant molecular mechanism, were examined The results of a Cell Counting Kit 8 assay, a flow cytometric Annexin-V/propidium iodide assay and western blot analysis demonstrated that ZA exhibited a significant inhibition of cell viability and induction of apoptosis at concentrations >10 µM. Subsequently, the effect of ZA on cell differentiation at concentrations <1 µM were investigated. In this condition, ZA inhibited bone nodule formation and decreased the activity of alkaline phosphatase. The results of reverse transcription-quantitative polymerase chain reaction and western blot analyses indicated that ZA downregulated the expression levels of the marker genes and proteins associated with osteogenic differentiation. Further investigation revealed that the suppression of differentiation by ZA was associated with decreased expression of bone morphogenetic protein-2 (BMP-2) and downregulation of the phosphorylation levels in the downstream extracellular signal-regulated kinase 1/2 and p38 pathways. These adverse effects of ZA were observed to be concentration-dependent. The results from the present study suggested that ZA at higher concentrations induces cytotoxicity towards osteoblasts, and ZA at lower concentrations suppresses osteoblast differentiation by downregulation of BMP-2. These results assist in further understanding the mechanisms of BRONJ.

Dendritic Cells Cause Bone Lesions in a New Mouse Model of Histiocytosis

Langerhans cell histiocytosis (LCH) is a rare disease caused by the clonal accumulation of dendritic Langerhans cells, which is often accompanied by osteolytic lesions. It has been reported that osteoclast-like cells play a major role in the pathogenic bone destruction seen in patients with LCH and these cells are postulated to originate from the fusion of DCs. However, due to the lack of reliable animal models the pathogenesis of LCH is still poorly understood. In this study, we have established a mouse model of histiocytosis- recapitulating human disease for osteolytic lesions seen in LCH patients. At 12 weeks after birth, severe bone lesions were observed in our multisystem histiocytosis (Mushi) model, when CD8α conventional dendritic cells (DCs) are transformed (MuTuDC) and accumulate. Most importantly, our study demonstrates that bone loss in LCH can be accounted for the transdifferentiation of MuTuDCs into functional osteoclasts both in vivo and in vitro. Moreover, we have shown that injected MuTuDCs reverse the osteopetrotic phenotype of oc/oc mice in vivo. In conclusion, our results support a crucial role of DCs in bone lesions in histiocytosis patients. Furthermore, our new model of LCH based on adoptive transfer of MuTuDC lines, leading to bone lesions within 1–2 weeks, will be an important tool for investigating the pathophysiology of this disease and ultimately for evaluating the potential of anti-resorptive drugs for the treatment of bone lesions.

Effect of bisphosphonates on orthodontic tooth movement-an update

Bisphosphonates are a synthetic class of pyrophosphate analogues that are powerful inhibitors of bone resorption which are commonly used as a medication for the prevention and therapy of osteoporosis and osteopenia, also used to treat tumor diseases. As it affects bone metabolism, it is said to have an influence on orthodontic treatment and tooth movement. Also, this review gives an insight into the reported effects of Bisphosphonate medication in literature highlighting the status quo of scientific research regarding effects of Bisphosphonates on orthodontic tooth movement. A systematic literature search was done in Medline database (Pubmed) for the appropriate keywords. Manual handsearch was also done. From the available evidence it can be concluded that the duration of orthodontic treatment is increased for patients under Bisphosphonate therapy as they interfere with the osteoclastic resorption. However, they may be beneficial for anchorage procedures. Further long term prospective randomized controlled trials are required to assess possible benefits and adverse effects of bisphosphonate treatment, before Bisphosphonates can be therapeutically used in orthodontics.

BRONJ-related jaw bone is associated with increased Dlx-5 and suppressed osteopontin-implication in the site-specific alteration of angiogenesis and bone turnover by bisphosphonates

OBJECTIVES

Site-specific suppression of bone remodelling has been implicated in bisphosphonate-(BP)-related osteonecrosis of the jaws (BRONJ). Due to the origin of jaw bone from cranial neural crest, osseous differentiation is regulated specifically by the antagonizing BMP-2-downstream-transcription factors Msx-1 and Dlx-5. Osteopontin has been implicated in bone remodelling and angiogenesis. The osteoblast and osteoclast progenitor proliferation mediating Msx-1 has been demonstrated to be suppressed in BRONJ. In vitro BPs were shown to increase Dlx-5 and to suppress osteopontin expression. This study targeted Dlx-5 and osteopontin in BRONJ-related and BP-exposed jaw bone compared with healthy jaw bone samples at protein- and messenger RNA (mRNA) level, since increased Dlx-5 and suppressed osteopontin might account for impaired bone turnover in BRONJ.

MATERIALS AND METHODS

Fifteen BRONJ-exposed, 15 BP-exposed and 20 healthy jaw bone samples were processed for real-time reverse transcription polymerase chain reaction (RT-PCR) and for immunohistochemistry. Targeting Dlx-5, osteopontin and glyceraldehyde 3-phosphate dehydrogenase mRNA was extracted, quantified by the LabChip-method, followed by quantitative RT-PCR. For immunohistochemistry, an autostaining-based alkaline phosphatase antialkaline phosphatase (APAPP) staining kit was used. Semiquantitative assessment was performed measuring the ratio of stained cells/total number of cells (labelling index, Bonferroni adjustment).

RESULTS

The labelling index was significant decreased for osteopontin (p < 0.017) and significantly increased for Dlx-5 (p < 0.021) in BRONJ samples. In BRONJ specimens, a significant fivefold decrease in gene expression for osteopontin (p < 0.015) and a significant eightfold increase in Dlx-5 expression (p < 0.012) were found.

CONCLUSIONS

BRONJ-related suppression of bone turnover is consistent with increased Dlx-5 expression and with suppression of osteopontin. The BP-related impaired BMP-2-Msx-1-Dlx-5 axis might explain the jaw bone specific alteration by BP.

CLINICAL RELEVANCE

The findings of this study help to explain the restriction of RONJ to craniofacial bones. BRONJ might serve as a model of disease elucidating the specific signal transduction of neural crest cell-derived bone structures in health and disease.

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

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

The effects of bisphosphonate on the remodeling of different irregular bones in mice

BACKGROUND

We aimed to compare the effects of bisphosphonate on the remodeling of irregular bones (the jaw and ilium) in mice after trauma.

METHODS

To verify the feasibility of modeling osteonecrosis, 20 mice were injected intraperitoneally with zoledronate and dexamethasone (ZOL&DEX group), dexamethasone (DEX group), or phosphate-buffered saline (PBS) [control (CTR) group]. Mice then underwent extraction of the right maxillary first molar and creation of an artificial bony cavity in the ilium. Bone sections were stained with H&E for morphological studies. To further compare differences between the maxilla and the ilium caused by similar traumas, 80 mice were injected intraperitoneally with ZOL&DEX or PBS. Pathological progression at the injury sites was assessed at 1 day and at 1, 3, and 8 weeks after trauma using micro-computed tomography (CT), H&E and immunohistochemistry analyses, high-performance liquid chromatography-mass spectrometry, and enzyme-linked immunosorbent assay.

RESULTS

Only the ZOL&DEX model group effectively developed osteonecrosis. Bony sequestra, osseous sclerosis, unhealed mucosa, and radiopaque alveolar bone were found in the maxilla. In the ilium, there was a lower frequency of osteonecrotic disease and osseous sclerosis, and less suppression of bone remodeling than in the maxilla following long-term bisphosphonate administration. Zoledronate levels were higher in the maxilla. ZOL&DEX treatment suppressed the levels of RANKL and IL-17, but induced an upregulation of osteoprotegerin and FAM20C in both bones.

CONCLUSION

Accumulation of bisphosphonate may increase the incidence of osteonecrosis. The RANKL/OPG pathway and IL-17 and FAM20C cytokines play key roles in the progression of pathologically abnormal bone remodeling.

Clinical and radiographic evaluation of the efficacy of platelet-rich plasma combined with hydroxyapatite bone graft substitutes in the treatment of intra-bony defects in maxillofacial region

OBJECTIVE

The aim of this study is to evaluate the efficacy of platelet-rich plasma (PRP) clinically and radiographically when combined with bovine derived hydroxyapatite (HA) bone grafting materials and resorbable collagen membranes for the treatment of intra-bony defects frequently seen at the distal aspect of mandibular second molars following the surgical extraction of fully impacted mandibular wisdom teeth.

STUDY DESIGN

Eighteen patients were scheduled for post-operative visits at 1, 3 and 6 months post-operatively, probing depths were measured and digital panoramic radiographs were taken.

RESULTS

There were no significant differences on probing depths among two groups. Radiographic assessment also showed no significant difference among groups at 1st and 6th month intervals, while 3 months post-operatively the amount of radiographic density at the PRP side was significantly higher.

CONCLUSION

Combined use of PRP and bovine-derived HA graft materials for the treatment of intra-bony defects might be an appropriate approach when the main goal is providing earlier bone regeneration.

Zoledronate inhibits receptor activator of nuclear factor kappa-B ligand-induced osteoclast differentiation via suppression of expression of nuclear factor of activated T-cell c1 and carbonic anhydrase 2

Bisphosphonates (BPs) are widely used in the prevention of skeletal-related events (SRE), including osteoporosis, skeletal metastases of malignant tumours, and multiple myeloma. Osteonecrosis of the jaw (ONJ) is frequently reported as a major adverse effect induced by BP treatment. The receptor activator of the nuclear factor kappa-B ligand (RANKL) inhibitor, denosumab, has recently been used to prevent SRE, but the frequency of ONJ induced by denosumab is similar to that by BPs. This finding suggests that the inhibition of RANKL-mediated osteoclastogenesis may have a close relationship with the occurrence of ONJ. We therefore investigated the expression status of RANKL-inducible genes in zoledronate-treated mouse osteoclast precursor cells. The molecular targets of zoledronate in the RANKL signal pathway and additional factors associated with osteoclastogenesis were analysed by genome-wide screening. Microarray analysis identified that among 31 genes on 44 entities of RANKL-inducible genes, the mRNA expression level of two genes, i.e., nuclear factor of activated T-cells c1 (NFATc1) and carbonic anhydrase 2 (CAII), was decreased in zoledronate-treated cells. Subsequent analyses verified that these two genes were significantly silenced by zoledronate treatment and that their expression was restored following inhibition of zoledronate action by geranylgeraniol. Zoledronate inhibited RANKL-induced osteoclast differentiation by suppression of NFATc1 and CAII gene expression. Our results suggest that these genes might be common targets for zoledronate and denosumab in the mechanism underlying RANKL-induced osteoclast differentiation. A clear understanding of the common molecular mechanisms of bone-remodelling agents is thus essential for prevention of ONJ.

Distinctive role of 6-month teriparatide treatment on intractable bisphosphonate-related osteonecrosis of the jaw

The administration of teriparatide (TPTD) in conjunction with periodontal care could provide faster and more favorable clinical outcomes in previously refractory bisphosphonate-related osteonecrosis of the jaws (BRONJ) cases compared to conventional dental care, combination of surgery and antimicrobial treatment. We also found that underlying vitamin D levels might influence the response to TPTD treatment.

INTRODUCTION

Treatment of BRONJ is quite challenging and there are no standard treatment modalities. In this retrospective, longitudinal study, we examined whether additional TPTD administration could be beneficial for the resolution of BRONJ lesions compared to conservative management, such as antimicrobial treatment with or without surgery, and also studied the factors influencing the response to TPTD.

METHODS

Twenty-four cases of intractable BRONJ were included: 15 subjects were assigned to the TPTD group and the other 9 subjects, who refused TPTD administration, were assigned to the non-TPTD group. All subjects in both groups continued calcium and vitamin D supplementation and the TPTD group additionally received a daily subcutaneous injection of 20 μg TPTD for 6 months.

RESULTS

While 60.0% of the non-TPTD group showed one stage of improvement in BRONJ, 40.0% of the group did not show any improvement in disease status. In the TPTD group, 62.5% of the treated subjects showed one stage of improvement and the other 37.5% demonstrated a marked improvement, including two stages of improvement or complete healing, and there was not a single case that did not improve. The clinical improvement of BRONJ was statistically better in the TPTD group after the 6-month treatment (p < 0.05). Moreover, patients with higher baseline serum 25(OH)D levels showed better clinical therapeutic outcomes with TPTD.

CONCLUSIONS

We observed the beneficial effects of TPTD on BRONJ, and subjects with optimal serum vitamin D concentrations seemed to reap the maximum therapeutic effects of TPTD. A prospective, randomized, controlled trial should be needed to further evaluate the therapeutic efficacy of TPTD in the resolution of BRONJ.

Antiresorptive drug-related osteonecrosis of the jaw

Nitrogen-containing and non-nitrogen-containing bisphosphonates have been implicated in the development of osteonecrosis of the jaw (ONJ), a condition termed bisphosphonate-related OHJ. Other antiresorptive drugs have been implicated in the development of OHJ, hence the new term antiresorptive drug-related ONJ. The underlying pathogenesis remains unclear, and no definite diagnosis or cure has been established for this debilitating condition. This article reviews some of the most common antiresorptive drugs with their associated risks of ONJ and the current understanding of the pathogenesis ONJ, and summarizes current clinical guidelines.

Platelet-Rich Plasma in Treatment of Zoledronic Acid-Induced Bisphosphonate-related Osteonecrosis of the Jaws

Background:

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a well-known challenging entity warranting management. Platelet-Rich Plasma (PRP) plays an important role in bone biology by enhancing bone repair and regeneration.

Objectives:

The aim of this animal study was to evaluate the effects of PRP on zoledronic acid-induced BRONJ.

Materials and Methods:

Seven rats were given 0.04 mg Zoledronic acid intravenously once a week for five weeks. Two weeks later, the animals underwent extraction of their first lower molars, bilaterally. After clinical confirmation of the osteonecrosis, PRP was injected randomly into one of the extraction sockets of each rat. Three weeks later, all rats were sacrificed in order to obtain histological sections. The analysis of epithelialization was performed by McNamar’s test, and the analysis of osteogenesis and angiogenesis was performed by the Wilcoxon Sign Rank test. P value was set at 0.05.

Results:

We found no significant differences between the two groups regarding the amount of epithelialization, angiogenesis or sequestrum formation (P > 0.05), but a significant difference was seen between the two groups regarding the amount of existing vital bone (P < 0.05).

Conclusions:

Our study demonstrates positive results (preservation or regeneration of bone) using PRP in treatment of BRONJ. Although PRP may enhance osseous regeneration, long-term follow-ups are required to confirm its benefits.

Bisphosphonate-associated osteonecrosis of jaw reoccurrence after methotrexate therapy: a case report

INTRODUCTION

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a well-known complication caused by amino-bisphosphonate therapy. We document one case of BRONJ associated with oral administration of methotrexate, a known immunosuppressive drug used to treat rheumatoid arthritis.

METHODS

A 66-year-old woman was referred for evaluation and endodontic surgery of recently re-treated tooth 13. Tooth 14 was extracted 3 months prior, and the extraction site had not completely healed. Her medical history revealed rheumatoid arthritis and osteoporosis. She had been taking Fosamax (alendronate) 70 mg daily. Because of adequate root canal therapy of tooth 13, endodontic surgery was performed. Five months after apicoectomy, her symptoms had not changed. Tooth 13 was extracted, and the socket healed without complications. The socket of extracted tooth 14 was also healing. At the 3-month recall visit, bone exposure and purulent discharge at the site of extracted tooth 14 were noted. The patient had recently received methotrexate. The methotrexate was discontinued, and she was given course of amoxicillin.

RESULTS

At the 18-month follow-up, the healing progressed, and the wound was closed.

CONCLUSIONS

A medication that suppresses the immune system such as methotrexate may complicate the management of BRONJ. Once a diagnosis of BRONJ is made, a closely monitored conservative approach is recommended.

Oxidative stress in bisphosphonate-related osteonecrosis of the jaws

OBJECTIVES

To analyze whether oxidative stress (OS) changes are present in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ) versus controls.

MATERIALS AND METHODS

Oxidative stress was analyzed in serum and unstimulated saliva of three groups: Group 1 consisted of 24 patients who had been treated with intravenous bisphosphonates (ivBPs) and developed BRONJ, group 2 consisted of 20 patients who had received ivBPs and did not develop BRONJ, and group 3 comprised 17 control subjects. Reduced glutathione (GSH), malondialdehyde (MDA), oxidized glutathione (GSSG), and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxo-dG) levels, as well as the GSSG/GSH ratio, were measured.

RESULTS

Mean serum and saliva levels of MDA, GSSG, and 8-oxo-dG and the GSSG/GSH ratio were significantly higher in patients with BRONJ than in controls. We found no significant difference in OS according to BRONJ stage, sex, or location in the jaws. Logistic regression analysis revealed that the GSSG/GSH ratio was a significant factor predicting the development of BRONJ (P = 0.01).

CONCLUSIONS

Oxidative stress was detected in patients with BRONJ, and the GSSG/GSH ratio was the most significant OS variable found; it was a significant factor predicting the development of BRONJ.

Clinical study evaluating the effect of bevacizumab on the severity of zoledronic acid-related osteonecrosis of the jaw in cancer patients

This study aimed to evaluate the effect of bevacizumab (BVZ) on the severity of osteonecrosis of the jaw (ONJ) in a cohort of cancer patients treated with intravenous zoledronic acid (ZA). We reviewed 42 oncologic patients with ONJ between 2007 and 2010. Only patients with solids tumors and who had received ZA were included. Data analyses included age, sex, underlying disease, ZA and BVZ dosages, dental history and ONJ characteristics. Of the 42 ONJ patients treated with ZA, 10 also received BVZ. In the 10 ZA/BVZ patients, the mean duration of ZA treatment at the time of ONJ diagnosis was 12.4 months (±6.8), compared to 22.9 months (±4.8) in the 32 patients who received ZA only (p<0.05). Cox's model analysis of the delay to ONJ diagnosis confirmed the impact of BVZ on ONJ diagnosis. In the ZA/BVZ-treated group, 7 (70%) patients developed spontaneous osteonecrosis. Multiple logistic regression analysis showed that ZA/BVZ is associated with increased risk of developing spontaneous ONJ (OR 6.07; 95% CI, [1.3-28.2], p<0.05). And finally, the number of ONJ lesions was increased in the ZA/BVZ-treated group compared to the ZA group (p<0.01). Other clinical conditions as type of tumor (prostate, breast…), cancer severity or other chemotherapy drugs also could be involved in ONJ evolution. However, this study demonstrates for the first time the potential negative influence of BVZ on the incidence and severity of ONJ in patients receiving ZA. Within the study limits, our results suggest that combination ZA/BVZ treatment may possibly predispose to the development of spontaneous and earlier ONJ.

Stomatological management of head and neck cancer patients treated with chemotherapy and radiotherapy

Treatment of head and neck cancer with radiotherapy and/or chemotherapy can cause oral damage. Long-term treatment can damage the salivary glands, the oral mucosa, and the maxilla, leading to altered production of saliva and to multiple infections. These lesions can be prevented, limited or avoided by thorough evaluation prior to treatment and by therapeutic follow-up and preventive measures. The dentist must have strong medical knowledge of the possible short-, medium-, and long-term oral complications of the cancer treatment, and must have knowledge of the protocols for oral management of cancer patients. The availability of a multidisciplinary medical team together with a dentist to attend to the patient prior to the cancer treatment, as well as close communication between team members during and after treatment, is crucial. The aim of the present study was review the stomatological management of head and neck cancer patients treated with chemotherapy and radiotherapy and summarizing current treatments, therapeutic innovation and tissue regeneration perspectives.

Bisphosphonate-related osteonecrosis of the jaws: legal liability from the perspective of the prescribing physician

Recently, it has been reported that patients administered with bisphosphonates (BP), in particular cancer patients receiving intravenous amino-bisphosphonates, as well as patients taking oral BP for prevention/treatment of diseases of altered bone turnover, may be affected by a significant adverse reaction-BP-related osteonecrosis of the jaws (BRONJ). This condition may cause high morbidity and detriment of quality of life. Its treatment is complex and often unsatisfactory, and prevention strategies may have limited effectiveness, if any; thus, BRONJ may become a source of litigation in the near future. Although most cases seem to be triggered by invasive dental procedures and oral health care providers are more exposed to malpractice claims and legal actions pursuant to BRONJ, the attribution of liability requires caution. In fact, types of possible negligence claims against oral health care providers have already been highlighted. However, according to the medico-legal methodology, since BRONJ is an adverse reaction to BP administration, the attribution of liability, if any, requires a comprehensive consideration of the chain of events and figures acting before, and potentially related to BRONJ. The physician prescribing BP at the start of this chain has specific duties which we are going to address, and breaching these duties may set the stage for potential liability claims.