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Mandibular Bone (mandibular + bone)
Selected AbstractsStudies on dentin grafts to bone defects in rabbit tibia and mandible; development of an experimental modelDENTAL TRAUMATOLOGY, Issue 1 2009Lars Andersson This property may possibly be used as an alternative or supplement to bone grafting to defective areas after trauma prior to treatment with osseointegrated implants. Hence, the objective of this study was to investigate if dentin can be used as a graft in bone defects in an experimental rabbit model. Materials and Methods:, Eight New Zealand White Rabbits were used to prepare bone cavities either in the angle of the mandible or tibia. Six of the eight tibial and six of the eight mandibular bone defects were filled with dentin blocks from human premolars which were extracted for orthodontic treatment. Two mandibular and two tibial bone cavities were used as controls and all the rabbits were sacrificed after 3 months. Radiographic and histological examinations were performed. Results:, There was a difference in healing pattern between the mandibular and tibial defects. In the mandible, the dentin blocks were resorbed to a larger extent and more often surrounded by fibrous tissue, probably due to the fact that the dentin blocks were mobile because of the thin mandibles and muscular activity in that area. Only some dentin blocks were ankylosed with the mandibular bone. In the tibia however, all dentin blocks were fused to bone over a large area. Osseous replacement resorption was seen. In control cavities, bone formation was seen but was never complete. No signs of inflammatory changes were seen in any fused grafts. Conclusions:, Dentin grafts have a potential to be incorporated in bone without inflammation and can be used as bone inducer and later replaced by bone. Thus, rabbit tibia served as a better model for further studies of this phenomenon when compared to the mandible. [source] Low-intensity pulsed ultrasound accelerates periodontal wound healing after flap surgeryJOURNAL OF PERIODONTAL RESEARCH, Issue 2 2008H. Ikai Background and Objective:, A study was conducted to evaluate the effects of low-intensity pulsed ultrasound on wound healing in periodontal tissues after mucoperiosteal flap surgery. Material and Methods:, Bony defects were surgically produced bilaterally at the mesial roots of the mandibular fourth premolars in four beagle dogs. The flaps were repositioned to cover the defects and sutured after scaling and planing of the root surface to remove cementum. The affected area in the experimental group was exposed to low-intensity pulsed ultrasound, daily for 20 min, for a period of 4 wk from postoperative day 1 using a probe, 13 mm in diameter. On the control side, no ultrasound was emitted from the probe placed contralaterally. After the experiment, tissue samples were dissected out and fixed in 10% formalin for histological and immunohistochemical analyses. Results:, The experimental group showed that the processes in regeneration of both cementum and mandibular bone were accelerated by low-intensity pulsed ultrasound compared with the control group. In addition, the expression level of heat shock protein 70 was higher in the gingival epithelial cells of the low-intensity pulsed ultrasound-treated tooth. Conclusion:, Our results suggest that osteoblasts, as well as cells in periodontal ligament and gingival epithelium, respond to mechanical stress loaded by low-intensity pulsed ultrasound, and that ultrasound accelerates periodontal wound healing and bone repair. [source] Masticatory stress and the mechanics of "wishboning" in colobine jawsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009David J. Daegling Abstract Cercopithecoid monkeys experience relatively high strains along the lingual aspect of the mandibular symphysis because of lateral transverse bending of the mandibular corpora ("wishboning") during mastication. Hylander (Am J Phys Anthropol 64 (1984) 1,46; Am Zool 25 (1985) 315,330) demonstrated that the distribution of strains arising from wishboning loads is comprehensible with reference to the mechanics of curved beams. Theory of curved beams suggests that lingual tensile strains are some multiple of labial compressive strains, yet limitations of experimental methods and uncertainty in estimating parameters needed for theoretical calculations have confounded attempts to characterize the magnitude of this disparity of normal strains. We evaluate the theoretical disparity of normal strains in wishboning in comparison to in vitro strains collected under controlled loads for a sample of mandibles representing two colobine species (N = 6). These data suggest that in colobine monkeys, maximum normal lingual strains should be at least twice maximum labial strains. In addition, we reexamine the distribution of symphyseal stress under an assumption of asymmetric bending, a general approach for calculation of stress appropriate for members that lack a plane of symmetry and are bent along an axis that is not coincident with the member's principal axes. Under asymmetric bending in colobine mandibles, the effect of symphyseal inclination on lingual strain is mitigating at the superior transverse torus and exacerbating at the inferior transverse torus. Relative compliance of colobine mandibular bone further supports the hypothesis that the structural and material properties of the colobine mandibular symphysis do not represent a morphological strategy for minimizing masticatory strain. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Bisphosphonate-related osteonecrosis of the jaw and its associated risk factors: A belgian case seriesTHE LARYNGOSCOPE, Issue 2 2009Sven Saussez MD Abstract Objectives: Bisphosphonate-related osteonecrosis of the jaw (BROJ) is a serious oral complication of bisphosphonate (BP) treatment involving the exposure of necrotic maxillary or mandibular bone. Our purpose is to describe the clinical presentation of 34 cases of BROJ and to identify potential risk factors. Study Design: A retrospective study was performed in four Belgian institutions. Methods: Complete medical histories were recorded and analyzed. These data include age, gender, initial disease requiring BP, type and duration of BP treatment, symptomatology and location of BROJ, prior dental procedures, treatment of the BROJ and treatment outcome, and radiographic, histological, and microbiological data. Results: Bisphosphonates (BP) were used in the management of disseminated cancers in 30 patients (88.5% of total studied), while four patients received BP due to osteoporosis (11.5%). The most frequently used BP was zoledronic acid in 29 patients (83%). Microbiological data obtained in 25 patients demonstrated that 72% of these patients were infected or colonized by an actinomyces. Eight of the 14 patients (57%) who received only medical treatment were cured. Of the 20 patients who underwent surgical treatments, only four were completely cured (20%). BROJ lesions smaller than 1 cm are associated with better prognosis in terms of treatment outcomes (P = .0009). Local treatments combined with long-term antibiotics are also correlated with better prognosis (P = .02). Conclusions: Lesions smaller than 1 cm and lesions that were subject to medical treatments are associated with a better outcome. Surgical treatments appear to be non-beneficial for BROJ. Laryngoscope, 119:323,329, 2009 [source] Micromotion and Stress Distribution of Immediate Loaded Implants: A Finite Element AnalysisCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 4 2009A. Fazel DDS ABSTRACT Background: Primary stability and micromotion of the implant fixture is mostly influenced by its macrodesign. Purpose: To assess and compare the peri-implant stress distribution and micromotion of two types of immediate loading implants, immediate loaded screw (ILS) Nisastan and Xive (DENTSPLY/Friadent, Monnheim, Germany), and to determine the best macrodesign of these two implants by finite element analysis. Methods: In this experimental study, the accurate pictures of two fixtures (ILS: height = 13, diameter = 4 mm and Xive: height = 13, diameter = 3.8 mm) were taken by a new digital camera (Nikon Coolpix 5700 [Nikon, Japan], resolution = 5.24 megapixel, lens = 8× optical, 4× digital zoom). Following accurate measurements, the three-dimensional finite element computer model was simulated and inserted in simulated mandibular bone (D2) in SolidWorks 2003 (SolidWork Corp., MA, USA) and Ansys 7.1 (Ansys, Inc., Canonsburg, PA, USA). After loading (500 N, 75° above horizon), the displacement was displayed and von Mises stress was recorded. Results: It was found that the primary stability of ILS was greater (152 µm) than Xive (284 µm). ILS exhibited more favorable stress distribution. Maximum stress concentration found in periapical bone around Xive (,30 MPa) was lesser than Nisastan (,37 MPa). Conclusions: Macrodesign of ILS leads to better primary stability and stress distribution. Maximum stress around Xive was less. [source] FGF signaling in mandibular skeletogenesisORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2 2007M Mina Structured Abstract Authors,,, Mina M, Havens B Objective,,, To examine the functions of FGF/FGFR signaling during mandibular skeletogenesis in ovo. Design,,, We examined the effects of inhibition of FGF signaling during mandibular skeletogenesis by overexpressing replication-competent RCAS virus encoding a truncated form of FGFR3 in the chicken mandibular process between stages 17 and 26. Results,,, Injection of RCAS-dnFGFR3 into the developing mandible resulted in abnormalities in a stage- and region-dependent manner. Injection at early stages of development resulted in the truncation of Meckel's cartilage, severely reduced outgrowth of the mandibular process and absence of five of the mandibular bones. Injection at later stages did not affect the outgrowth of the mandibular process and Meckel's cartilage but resulted in abnormalities in mandibular osteogenesis in a region-specific manner. The bones in the more caudal region were frequently truncated whereas bones in the more rostral regions such as dentary and splenial bones were frequently absent. Conclusion,,, Together these experiments have revealed essential roles for FGF/FGFR signaling in the elongation of Meckel's cartilage, development of osteogenic condensations and appositional growth of mandibular bones. [source] | ||||||||||