The Mandible Ameliorates Facial Allograft Rejection and Is Associated with the Development of Regulatory T Cells and Mixed Chimerism.

Vascularized composite allografts contain various tissue components and possess relative antigenicity, eliciting different degrees of alloimmune responses. To investigate the strategies for achieving facial allograft tolerance, we established a mouse hemiface transplant model, including the skin, muscle, mandible, mucosa, and vessels. However, the immunomodulatory effects of the mandible on facial allografts remain unclear. To understand the effects of the mandible on facial allograft survival, we compared the diversities of different facial allograft-elicited alloimmunity between a facial osteomyocutaneous allograft (OMC), including skin, muscle, oral mucosa, and vessels, and especially the mandible, and a myocutaneous allograft (MC) including the skin, muscle, oral mucosa, and vessels, but not the mandible. The different facial allografts of a BALB/c donor were transplanted into a heterotopic neck defect on fully major histocompatibility complex-mismatched C57BL/6 mice. The allogeneic OMC (Allo-OMC) group exhibited significant prolongation of facial allograft survival compared to the allogeneic MC group, both in the presence and absence of FK506 immunosuppressive drugs. With the use of FK506 monotherapy (2 mg/kg) for 21 days, the allo-OMC group, including the mandible, showed prolongation of facial allograft survival of up to 65 days, whereas the myocutaneous allograft, without the mandible, only survived for 34 days. The Allo-OMC group also displayed decreased lymphocyte infiltration into the facial allograft. Both groups showed similar percentages of B cells, T cells, natural killer cells, macrophages, and dendritic cells in the blood, spleen, and lymph nodes. However, a decrease in pro-inflammatory T helper 1 cells and an increase in anti-inflammatory regulatory T cells were observed in the blood and lymph nodes of the Allo-OMC group. Significantly increased percentages of donor immune cells were also observed in three lymphoid organs of the Allo-OMC group, suggesting mixed chimerism induction. These results indicated that the mandible has the potential to induce anti-inflammatory effects and mixed chimerism for prolonging facial allograft survival. The immunomodulatory understanding of the mandible could contribute to reducing the use of immunosuppressive regimens in clinical face allotransplantation including the mandible.

Comparison of Different Decalcification Methods Using Rat Mandibles as a Model.

Selection of decalcification agents is an essential consideration when processing mineralized tissues because the integrity and immunohistochemical characteristics of the tissues may be affected. Here, we report results obtained from the decalcification of rat mandibles using 10% ethylenediaminetetraacetic acid (EDTA) at room temperature (RT), 10% EDTA at 37C, 5% nitric acid, and 10% formic acid at RT. Decalcification endpoints were determined by microcomputed tomography. Morphological preservation and antigenicity were evaluated by hematoxylin and eosin staining and immunohistochemistry. Decalcification of the anterior and posterior portions of the mandible took 220 and 191 hr in 10% EDTA RT, 102 and 73 hr in 10% EDTA 37C, 13.5 and 4.3 hr in 5% nitric acid, and 140 and 36 hr in 10% formic acid, respectively. Decalcification in 10% EDTA at 37C was accelerated, but 10% EDTA at RT provided optimal results for immunohistochemistry and cellular and structural details. Decalcification using 5% nitric acid was accomplished in the shortest time and exhibited good cellular and architectural morphology, whereas 10% formic acid was suboptimal with respect to tissue and cellular morphology. Despite being the slowest method, EDTA at RT is still the recommended method for decalcifying mineralized tissues; however, if rapid decalcification is needed, 5% nitric acid is the best option, yielding acceptable tissue integrity and speed.

Associations of alveolar bone loss and interleukin-1ß levels in one- and two-stage surgical procedures: a randomized prospective trial.

OBJECTIVE: Dental implants have been widely and successfully used in recent years as an alternative treatment for removable and fixed dental prostheses. The aim of this randomized prospective study was to determine the alveolar bone loss rate (ABLR) and IL-1ß levels in one- and two-stage surgical procedures. MATERIALS AND METHODS: This study included 40 patients with a single missing tooth in the posterior mandible; dental implants were inserted using a one-stage surgical procedure (Group I) or a two-stage surgical procedure (Group II). All clinical periodontal parameters were recorded; peri-implant crevicular fluid (PICF) samples were collected before loading (T0) and during the third (T1) and sixth (T2) months after loading. ABLR values were evaluated at T0 and T2 by using dental tomography. PICF was analysed after T2 samples were collected. The study was registered through clinicaltrials.gov; identifier NCT03045458. RESULTS: This study found that, the probing pocket depth was found to be significantly higher in Group I than Group II at both T1 and T2 (p < .05). There was no significant difference in other clinical parameters between the groups (p > .05). There was a significant difference between Group I ABLR values at T0 and T2 (p < .05). The PICF IL-1ß levels were not significantly different between groups (p > .05). CONCLUSIONS: Within the limitations of the short observational period and small sample size of this study, two-stage implant placement shows comparable clinical outcomes to implants placed using a one-stage placement protocol.

Effect of organic silicon, methylsulfonylmethane, and glucosamine sulfate in mandibular bone defects in rats.

Organic silicon (OS), glucosamine sulfate (GS), and methylsulfonylmethane (MSM) have been related to bone and connective tissue health and have been considered as basic therapy for osteoarthrosis disorders. Therefore, the aim was to analyze the effect of the association of these three components in mandibular bone defects in rats. Nine rats were used for histocompatibility test. In each animal was implanted the composition (70% OS, 15% GS, 15% MSM) and gutta percha (control) under the dorsal subcutaneous tissue. The samples were collected at 7, 14, and 21 days post-surgery and inflammatory events analyzed. In sequence, the composition was engrafted in mandibular bone defects of nine rats; bone defects without treatment were the control group. Analyses were performed at 7, 14, and 28 days post-surgery and samples were evaluated by scanning electron microscopy (SEM). For the histocompatibility test, both groups had a moderate inflammatory process at 7 days post-surgery and mild inflammatory process at 14 and 21 days. But in SEM analysis, the composition promotes an extensive reabsorption in cortical and crest alveolar bone, and great tooth root reabsorption. In conclusion, although the composition had positive result in the histocompatibility test, its direct application in mandibular bone defects caused intense resorption.

The effects of separating inferior alveolar neurovascular bundles on osteogenesis of tissue-engineered bone and vascularization.

AIM: To evaluate the effects of autologous blood vessels and nerves on vascularization. METHODS: A dog model of tissue-engineered bone vascularization was established by constructing inferior alveolar neurovascular bundles through the mandibular canal. Sixteen 12-month-old healthy beagles were randomly divided into two groups (n=8). Group A retained inferior alveolar neurovascular bundles, and Group B retained inferior alveolar nerves. Bone marrow mesenchymal stem cells were injected into ß-tricalcium phosphate to prepare internal tissue-engineered bone scaffold. A personalized titanium mesh was then prepared by rapid prototyping and fixed by external titanium scaffold. Two dogs in each group were sacrificed on the 30th, 45th, 60th and 90th postoperative days respectively. The bone was visually examined, scanned by CT, and subjected to HE staining, immunohistochemical staining, vascular casting and PCR to detect the changes in osteogenesis and vascularization. RESULTS: The two groups had similar outcomes in regard to osteogenesis and vascularization (P>0.05): both showed remarkable regenerative capacities. CONCLUSIONS: The model of tissue-engineered bone vascularization is potentially applicable in clinical practice to allow satisfactory osteogenesis and vascularization.

Diagnosis and management of osteonecrosis of the jaw: a systematic review and international consensus.

This work provides a systematic review of the literature from January 2003 to April 2014 pertaining to the incidence, pathophysiology, diagnosis, and treatment of osteonecrosis of the jaw (ONJ), and offers recommendations for its management based on multidisciplinary international consensus. ONJ is associated with oncology-dose parenteral antiresorptive therapy of bisphosphonates (BP) and denosumab (Dmab). The incidence of ONJ is greatest in the oncology patient population (1% to 15%), where high doses of these medications are used at frequent intervals. In the osteoporosis patient population, the incidence of ONJ is estimated at 0.001% to 0.01%, marginally higher than the incidence in the general population (<0.001%). New insights into the pathophysiology of ONJ include antiresorptive effects of BPs and Dmab, effects of BPs on gamma delta T-cells and on monocyte and macrophage function, as well as the role of local bacterial infection, inflammation, and necrosis. Advances in imaging include the use of cone beam computerized tomography assessing cortical and cancellous architecture with lower radiation exposure, magnetic resonance imaging, bone scanning, and positron emission tomography, although plain films often suffice. Other risk factors for ONJ include glucocorticoid use, maxillary or mandibular bone surgery, poor oral hygiene, chronic inflammation, diabetes mellitus, ill-fitting dentures, as well as other drugs, including antiangiogenic agents. Prevention strategies for ONJ include elimination or stabilization of oral disease prior to initiation of antiresorptive agents, as well as maintenance of good oral hygiene. In those patients at high risk for the development of ONJ, including cancer patients receiving high-dose BP or Dmab therapy, consideration should be given to withholding antiresorptive therapy following extensive oral surgery until the surgical site heals with mature mucosal coverage. Management of ONJ is based on the stage of the disease, size of the lesions, and the presence of contributing drug therapy and comorbidity. Conservative therapy includes topical antibiotic oral rinses and systemic antibiotic therapy. Localized surgical debridement is indicated in advanced nonresponsive disease and has been successful. Early data have suggested enhanced osseous wound healing with teriparatide in those without contraindications for its use. Experimental therapy includes bone marrow stem cell intralesional transplantation, low-level laser therapy, local platelet-derived growth factor application, hyperbaric oxygen, and tissue grafting.

Immunohistological expression of human ß-defensin-1 and human ß-defensin-2 in exacerbation of acute and secondary chronic osteomyelitis of the mandible.

BACKGROUND: The majority of patients diagnosed with osteomyelitis of the jaw have severe complaints. Unfortunately, the pathogenesis still remains unclear. Human ß-defensins expressed in epithelial and bone tissues as a part of the innate immunity may be involved in disease development. In this study, we hypothesize that expression levels of human ß-defensin-1 and -2 in the acute and secondary chronic osteomyelitis may be altered in comparison with healthy bone and with bisphosphonate-associated necrosis as well as irradiation from a previous study. METHODS: Bone samples were collected during surgical debridement in a total of eight patients suffering from acute or secondary chronic osteomyelitis of the jaw. Expression levels of hBD-1 and -2 were quantified and related to non-stained cells. Ratios were compared by one-way ANOVA and multiple tests by Holm-Bonferroni. RESULTS: Multiple testing revealed no significant differences for expression levels of human ß-defensin-1 between all groups, whereas labeling index of human ß-defensin-2 was significantly different between specimens of bisphosphonate-associated osteonecrosis of the jaws and all other groups. No significant difference occurred between samples of floride osteomyelitis and healthy bone for expression of hBD-1 and -2. CONCLUSIONS: Although the affected patients showed all clinical signs of acute inflammation, expression levels in acute and secondary chronic osteomyelitis in the jaws did not reveal statistically significant differences compared with healthy bone samples. The weak immunological host response in terms of a putative genetically predisposition should be further discussed as pathogenesis factor for osteomyelitis in the future.

Alveolar bone resorption induced by CD4+CD45RB high-density T-cell transfer in immunocompromised mice.

BACKGROUND: The aims of this study are to determine whether the antigen-inexperienced (naive, CD45RB high-density) T-cell (CD4(+)CD45RB(High) T-cell) transfer model is associated with alveolar bone resorption, to elucidate the local osteogenic/adipogenic potential of alveolar bone marrow stromal cells (ABCs) from T-cell-transferred animals, and to investigate the systemic osteogenic potential by transplanting human periodontal ligament stem cells (hPDLSCs) into these animals. METHODS: CD4(+)CD45RB(High) and CD4(+)CD45RB(Low) (antigen-experienced [memory, CD45RB low-density]) T cells were sorted and transferred into severe combined immunodeficiency (SCID) mice to induce inflammatory bowel disease-like syndrome (n = 8). hPDLSCs were transplanted into T-cell-transferred SCID mice to examine ectopic cementum formation 8 weeks after T-cell transfer. The mandibles and tibias of these mice were retrieved for microcomputed tomography (micro-CT), histomorphometric analysis, and isolation of ABCs 16 weeks after T-cell transfer. The in vitro osteogenic and adipogenic potentials of the ABCs were evaluated. RESULTS: Histologic and micro-CT analysis revealed that the transfer of CD4(+)CD45RB(High) T-cell subset was sufficient for alveolar bone resorption and affected the osteogenic/adipogenic potential of ABCs. Furthermore, it was found that CD4(+)CD45RB(High) T-cell-transferred animals have decreased systemic osteogenic potential, as evidenced using the in vivo ectopic hPDLSC transplantation model. CONCLUSION: CD4(+)CD45RB(High) T-cell transfer induced both alveolar bone resorption and reduced systemic osteogenic potential, with a concomitant downregulation of the osteogenic potential of ABCs.

Intramuscular 30 percent polymethylmethacrylate (PMMA) implants in a non-protein vehicle: an experimental study in rats / Implante intramuscular de polimetilmetacrilato (PMMA) 30 por cento, associado a veículo não-proteico: estudo experimental em ratos

INTRODUCTION: In the present study, the stability and biocompatibility of a 30 percent polymethylmethacrylate (PMMA) filling material implanted in the masseter muscle of rats were investigated according to the cytologic characteristics presented in the graft versus host reaction. METHODS: The study included 20 rats, which were divided into 4 groups: groups I, II, III, and IV corresponded to animals evaluated 7, 14, 45, and 60 days after surgery, respectively. The implant was placed in the right masseter muscle at the level of the mandibular angle. RESULTS: After 7 days, lymphoplasmacytic inflammatory infiltrates, a fibrous capsule, a large number of neutrophils, macrophages, and exudate were observed. The second group (14 days) showed granulation tissue composed of a lymphoplasmacytic inflammatory infiltrate, newly formed vessels, and a fibrous capsule. However, the second group also exhibited regeneration of the muscle fibers, and a decreased number of neutrophils and exudate. After 45 and 60 days, the inflammatory infiltrate decreased in intensity compared to the first 2 groups. CONCLUSIONS: The inflammatory reaction caused by PMMA is transient and does not compromise the function and the shape of the masseter muscle tissue, suggesting that PMMA is biocompatible.

INTRODUÇÃO: Este trabalho busca avaliar, em ratos, a estabilidade e a biocompatibilidade de um material de preenchimento à base de polimetilmetacrilato (PMMA) a 30 por cento implantado no músculo masseter, por meio do padrão, e a organização reacional no tecido receptor. MÉTODO: Foram utilizados 20 ratos, divididos em quatro grupos: grupo I, que correspondeu ao período de 7 dias de pós-operatório; grupo II, de 14 dias; grupo III, de 45 dias; e grupo IV, de 60 dias. O implante foi realizado no músculo masseter direito, na região do ângulo da mandíbula. RESULTADOS: No período de 7 dias, observou-se presença de infiltrado inflamatório linfoplasmocitário, com formação de cápsula fibrosa e presença de grande número de neutrófilos, macrófagos e formação de exsudatos. Em 14 dias, observou-se a formação de um tecido de granulação composto por infiltrado inflamatório linfoplasmocitário, vasos de neoformação e cápsula fibrosa. Porém, nesse tempo experimental, nota-se a regeneração das fibras musculares e a diminuição do número de neutrófilos e exsudatos. Após 45 dias e 60 dias, observou-se, no tecido muscular, diminuição da intensidade do infiltrado inflamatório, comparativamente aos tempos experimentais anteriores. CONCLUSÕES: A reação inflamatória provocada pelo PMMA é transitória e não compromete as funções e o contorno desse tecido muscular, o que sugere que o PMMA é biocompatível.

Loss of mandibular lymph node integrity is associated with an increase in sensitivity to HSV-1 infection in CD118-deficient mice.

Type I IFNs are potent antiviral cytokines that contribute to the development of the adaptive immune response. To determine the role of type I IFNs in this process in an infectious disease model, mice deficient in the type I IFN receptor (CD118(-/-)) were ocularly infected with HSV-1 and surveyed at times post infection in the nervous system and lymph node for virus and the host immune response. Virus titers were elevated in the trigeminal ganglia and brain stem with virus disseminating rapidly to the draining lymph node of CD118(-/-) mice. T cell and plasmacytoid dendritic cell infiltration into the brain stem was reduced in CD118(-/-) mice following infection, which correlated with a reduction in CXCL10 but not CXCL9 expression. In contrast, CXCL1 and CCL2 levels were up-regulated in the brainstem of CD118(-/-) mice associated with an increase in F4/80(+) macrophages. By day 5 post infection, there was a significant loss in T, NK, and plasmacytoid dendritic cell numbers in the draining lymph nodes associated with an increase in apoptotic/necrotic T cells and an appreciable lack of HSV-specific CD8(+) T cells. The adoptive transfer of HSV-specific TCR transgenic CD8(+) T cells into CD118(-/-) mice at the time of infection modestly reduced viral titers in the nervous system suggesting in addition to the generation of HSV-specific CD8(+) T cells, other type I IFN-activated pathways are instrumental in controlling acute infection.

Th1 immune response promotes severe bone resorption caused by Porphyromonas gingivalis.

Bacterial infections of the dental pulp result in soft tissue and alveolar bone destruction. It has been suggested that Th1 responses promote disease, whereas Th2 responses are protective. However, other studies have challenged this notion. To address this question, bone destruction was evaluated in mice immunized to develop strong and polarized Th1- or Th2-biased responses to the oral pathogen Porphyromonas gingivalis. Th1 bias was confirmed by the presence of high titers of serum IgG2a and the production of high levels of interferon (IFN)-gamma and no interleukin (IL)-4 by lymph node cells stimulated with P. gingivalis antigens. In contrast, Th2-biased animals had high titer IgG1 and no IgG2a, and their lymph node cells produced high levels of IL-4 but no IFN-gamma. Subsequent infection of the dental pulp with P. gingivalis caused extensive inflammation and alveolar bone destruction in Th1-biased mice, whereas Th2-biased mice and controls developed minimal lesions. Inflammatory granulomas in Th1-biased mice were heavily infiltrated with osteoclasts and had high local expression of IFN-gamma, IL-1alpha, and IL-1beta. Little or no IFN-gamma/IL-1alpha/IL-1beta and no obvious osteoclasts were detected in lesions of Th2-biased and control groups. These results directly demonstrate that specific Th1 responses promote severe infection-stimulated alveolar bone loss.

[Clinical, topographic, and morphological characteristics of pathological processes in the retromolar zone]. / Klinicheskie i topografomorfologicheskie osobennosti patologicheskikh protsessov retromoliarnoi oblasti.

Morphological variants of 20 tissue fragments of mandibular retromolar space were analyzed and the data were used for developing a protocol of treatment of difficult eruption of the mandibular third molar using biocomposite materials.

The histopathology of different foreign-body reactions in oral soft tissue and bone tissue.

Foreign bodies may be endogenous or exogenous and provoke chronic inflammation of the foreign-body type. The reaction provides a mechanism for elimination of the foreign body and the reaction pattern depends on the kind of tissue involved. In soft tissues there is cellular inflammation and fibrous encapsulation with macrophages. In bone, during the healing period, biomechanical factors determine whether a fibrous encapsulation or a bony covering develops demarcating the foreign material. The particular characteristics of the foreign-body reaction in bone explain the success of dental and orthopaedic implants.

Reconstruction of the mandible by means of a similar allogenic lyophilized mandibular segment. I. Morphological and immunological studies in monkeys.

Subperiosteal resection of the entire ramus including the condyle followed by immediate reconstruction using a similar allogenic lyophilized mandibular segment was performed in 5 adult monkeys (Macaca irus). One further animal served as a control for the operative technique and another provided the initial 2 rami for implantation into the first of the 5 experimental animals, while an additional animal was used to supply fresh bone specimens for immunological studies. Sequential polychrome labelling with oxytetracycline, DCAF and haematoporphyrin was used, and X-rays were taken at regular intervals; the reconstructed condyles proved to be radiographically and macroscopically indistinguishable from those of the control side. All reconstructed bone transplants took. Immunological investigations (leukocyte-migration-inhibition tests) revealed that lyophilized allogenic bone grafts exhibit reduced antigenicity.

Ann Otol Rhinol Laryngol [Suppl].

Mandibular replacement subsequent to major extirpative head and neck surgery is predisposed to complications in the best of hands. The most suitable prosthesis appears to be the previously resected mandible, both from the standpoint of antigenicity and configuration. This study establishes that in the canine mandible a healthy, revitalized osseous network is reestablished subsequent to resection, freezing and replacement of the mandibular body when the graft is immobilized. The neoosteogenesis is borne out by in vivo (technetium 99, methylene diphosphonate scanning) and histopathological (tetracycline fluorescence and polarizing microscopy) studies. This early work in the canine suggests the potential for application in the human when the procedure is further refined and perfected.