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Watanabe K, Lewis S, Guo X, Ni A, Lee BS, Deguchi T, Kim DG. Regional variations of jaw bone characteristics in an ovariectomized rat model. J Mech Behav Biomed Mater 2020; 110:103952. [PMID: 32957244 DOI: 10.1016/j.jmbbm.2020.103952] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 12/22/2022]
Abstract
Postmenopausal osteoporosis causes severe loss of bone quantity and quality in limb bone but has a lesser effect on jaw bone. Thus, the objective of this study was to examine whether ovariectomy (OVX) and mastication alter the regional variation of jaw bone characteristics. Sprague-Dawley female rats (6 months) were given a bilateral OVX or a sham operation (SHAM) (n = 10 for each group). After 2 months post-OVX, the hemi-mandible from each rat was dissected. A micro-computed tomography based mean, standard deviation (SD), the lower and upper 5th percentile (Low5 and High5) values of tissue mineral density (TMD) histograms were assessed for whole bone (WB), alveolar bone (AB), cortical bone (CB), and trabecular bone (TB) regions. Morphology of TB and periodontal ligament (PDL) was also obtained. Layers of AB were segmented up to 400 μm from the PDL. Mechanical properties at the tissue level were measured by nanoindentation at the same site by a single loading-unloading cycle of indentation in hydration. The AB and TB regions had significantly lower TMD Mean, Low5, and High5 but higher SD than the CB region for both sham and OVX groups (p < 0.01). TMD parameters of the OVX group rapidly increased up to 60 μm away from the PDL and were significantly higher than those of the sham group starting at 280 μm and farther in the CB region (p < 0.05). All values of morphological and nanoindentation parameters were not significantly different between sham and OVX groups (p > 0.06). Estrogen deficiency induced by OVX did not deteriorate bone characteristics including mineral density, morphology, and nanoindentation parameters in rat mandibles. Masticatory loading had an effect on the TMD parameters at the limited region of AB. These results provide insight into why osteoporosis-associated jaw bone fractures are extremely rare.
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Affiliation(s)
- Keiichiro Watanabe
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Samantha Lewis
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Xiaohan Guo
- Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, OH, 43210, USA
| | - Ai Ni
- Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, OH, 43210, USA
| | - Beth S Lee
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, 43210, USA
| | - Toru Deguchi
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Do-Gyoon Kim
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA.
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Rafferty KL, Baldwin MC, Soh SH, Herring SW. Mechanobiology of bone and suture - Results from a pig model. Orthod Craniofac Res 2019; 22 Suppl 1:82-89. [PMID: 31074147 DOI: 10.1111/ocr.12276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2018] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To compare the morphology and mechanical function of sutures in normal pigs and minipigs to those of Yucatan minipigs, a natural model for midfacial hypoplasia. SETTING AND SAMPLE POPULATION Research took place at the Department of Orthodontics at the University of Washington and used varying sample sizes of normal-snouted pigs and Yucatan minipigs. MATERIAL AND METHODS Skulls and heads were examined for morphology of the nasofrontal suture using computed tomography and histology. Strain gauge recordings were made of sutural strain during mastication and during cyclic tensile loading of the nasofrontal suture. RESULTS Sutures in Yucatans had narrower gaps than same-age normal pigs. The nasofrontal suture was simpler in construction and had more active osteoblasts on the bone fronts in Yucatans. The sutural ligament was less well organized, and based on a small sample, masticatory strain appeared to be lower than in normal minipigs. However, sutures were not fused and showed similar strains in response to the cyclic loading procedure. CONCLUSION Midfacial hypoplasia in Yucatan pigs has the likely proximate cause of hyperossification. Yet prior to fusion, the sutures appear to be amenable to treatment that would promote their growth rate.
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Affiliation(s)
| | - Michael C Baldwin
- Department of Oral Health Sciences, University of Washington, Seattle, Washington
| | - Shean Han Soh
- Department of Orthodontics, University of Washington, Seattle, Washington
| | - Susan W Herring
- Department of Orthodontics, University of Washington, Seattle, Washington.,Department of Oral Health Sciences, University of Washington, Seattle, Washington
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Ibrahim AY, Gudhimella S, Pandruvada SN, Huja SS. Resolving differences between animal models for expedited orthodontic tooth movement. Orthod Craniofac Res 2018. [PMID: 28643903 DOI: 10.1111/ocr.12175] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE To highlight differences in commonly used animal models of orthodontic tooth movement (OTM). METHODS Narrative review. RESULTS A critical review of the literature on animal models has become increasingly important in the last decade as methods to increase the rate of tooth movement have been intensely sought. We provide a review focusing on the rodent and canine models for expedited OTM and describe the challenges in extrapolation of the results to the clinical practice of orthodontics. We review and contrast the two (rodent, canine) most commonly used animal models for OTM. We then describe animal models to study bone adaptation, remodelling and modelling, which are keys events in describing and quantifying OTM. CONCLUSIONS Understanding the differences between animal models and their adaptation biology as it relates to OTM is key to make valid conclusions. The rodent model can be used to understand the initial phases of tooth movement. Unlike the dog model, the rodent model does not lend itself to understand prolonged adaptation in response to bodily tooth movement. Extrapolation of rate of tooth movement to humans is more challenging from rodent model data.
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Affiliation(s)
- A Y Ibrahim
- Division of Orthodontics, College of Dentistry, University of Kentucky, Lexington, KY, USA
| | - S Gudhimella
- Division of Orthodontics, College of Dentistry, University of Kentucky, Lexington, KY, USA
| | - S N Pandruvada
- Division of Orthodontics, College of Dentistry, University of Kentucky, Lexington, KY, USA
| | - S S Huja
- Division of Orthodontics, College of Dentistry, University of Kentucky, Lexington, KY, USA
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Exposto CR, Oz U, Callard JS, Allen MJ, Khurana H, Atri AD, Mo X, Fernandez SA, Tatakis DN, Edmonds K, Westgate PM, Huja SS. Oncologic doses of zoledronic acid induce site specific suppression of bone modelling in rice rats. Orthod Craniofac Res 2017. [PMID: 28643933 DOI: 10.1111/ocr.12164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To examine the effect of zoledronic acid (ZOL) on cortical bone modelling and healing of extraction sockets in the jaw bones of a rodent model. We hypothesized ZOL suppresses both the bone formation in the modelling mode in the jaw bones and alters the extraction site healing. MATERIAL & METHODS Rice rats were administered saline solution and two dose regimens of ZOL: 0.1 mg/kg, twice a week, for 4 weeks (n=17, saline=8 & ZOL=9) and a higher dose of 0.4 mg/kg, weekly, for 9 weeks (n=30, saline=15 & ZOL=15). Two pairs of fluorochrome bone labels were administered. Extraction of maxillary teeth was performed in maxilla. Mineral apposition rate, mineralizing surface and bone formation rate (BFR) were quantified on periodontal (PDL), alveolar and basal bone surfaces, and in the trabecular bone of proximal tibia. Bone volume (BV) was evaluated at extraction sockets. Multivariate Gaussian models were used to account for repeated measurements, and analyzes were conducted in SAS V9.3. RESULTS ZOL suppressed bone modelling (BFR/BS) at the PDL surfaces in the mandible (P<.05), but its effect was not significant at the periosteal surfaces of both jaws. BV for the healing sockets of ZOL treated animals was not significantly different (P=.07) compared to the saline group. ZOL suppressive effect was higher in the tibia compared to the jaws. CONCLUSION ZOL severely suppresses coupled remodelling in the tibia, and the suppression of bone formation in the modelling mode in the jaws demonstrates the site specific effects of ZOL in rice rats.
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Affiliation(s)
- C R Exposto
- Section of Orthodontics, Aarhus University, Aarhus, Denmark
| | - U Oz
- Department of Orthodontics, Near East University, North Nicosia, Northern Cyprus
| | - J S Callard
- Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - M J Allen
- Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | - H Khurana
- Division of Orthodontics, The Ohio State University, Columbus, OH, USA
| | - A D' Atri
- Division of Orthodontics, The Ohio State University, Columbus, OH, USA
| | - X Mo
- Biostatistics, The Ohio State University, Columbus, OH, USA
| | - S A Fernandez
- Biostatistics, The Ohio State University, Columbus, OH, USA
| | - D N Tatakis
- Periodontics, The Ohio State University, Columbus, OH, USA
| | - K Edmonds
- School of Natural Sciences, Indiana University Southeast, New Albany, IN, USA
| | - P M Westgate
- Department of Biostatistics, University of Kentucky, Lexington, KY, USA
| | - S S Huja
- Division of Orthodontics, College of Dentistry, University of Kentucky, Lexington, KY, USA
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Kubek DJ, Burr DB, Allen MR. Ovariectomy stimulates and bisphosphonates inhibit intracortical remodeling in the mouse mandible. Orthod Craniofac Res 2011; 13:214-22. [PMID: 21040464 DOI: 10.1111/j.1601-6343.2010.01497.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE The pathophysiology of osteonecrosis of the jaw (ONJ) is thought to be linked to suppression of intracortical remodeling. The aim of this study was to determine whether mice, which normally do not undergo appreciable amounts of intracortical remodeling, could be stimulated by ovariectomy to remodel within the cortex of the mandible and if bisphosphonates (BPs) would suppress this intracortical remodeling. MATERIAL AND METHODS Skeletally mature female C3H mice were either ovariectomized (OVX) or SHAM operated and treated with two intravenous doses of zoledronic acid (ZOL, 0.06 mg/kg body weight) or vehicle (VEH). This ZOL dose corresponds to the dose given to patients with cancer on a mg/kg basis, adjusted for body weight. Calcein was administered prior to sacrifice to label active formation sites. Dynamic histomorphometry of the mandible and femur was performed. RESULTS Vehicle-treated OVX animals had significantly higher (eightfold) intracortical remodeling of the alveolar portion of the mandible compared to sham--this was significantly suppressed by ZOL treatment. At all skeletal sites, overall bone formation rate was lower with ZOL treatment compared to the corresponding VEH group. CONCLUSIONS Under normal conditions, the level of intracortical remodeling in the mouse mandible is minimal but in C3H mice it can be stimulated to appreciable levels with ovariectomy. Based on this, if the suppression of intracortical remodeling is found to be part of the pathophysiology of ONJ, the ovariectomized C3H mouse could serve as a useful tool for studying this condition.
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Affiliation(s)
- D J Kubek
- Department of Anatomy and Cell Biology, University of Indianapolis, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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Huja SS, Mason A, Fenell CE, Mo X, Hueni S, D'Atri AM, Fernandez SA. Effects of Short-Term Zoledronic Acid Treatment on Bone Remodeling and Healing at Surgical Sites in the Maxilla and Mandible of Aged Dogs. J Oral Maxillofac Surg 2011; 69:418-27. [DOI: 10.1016/j.joms.2010.05.062] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 04/14/2010] [Accepted: 05/06/2010] [Indexed: 10/18/2022]
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The effects of bisphosphonates on jaw bone remodeling, tissue properties, and extraction healing. Odontology 2011; 99:8-17. [DOI: 10.1007/s10266-010-0153-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 10/10/2010] [Indexed: 01/22/2023]
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Ames MS, Hong S, Lee HR, Fields HW, Johnston WM, Kim DG. Estrogen deficiency increases variability of tissue mineral density of alveolar bone surrounding teeth. Arch Oral Biol 2010; 55:599-605. [PMID: 20541742 PMCID: PMC2902606 DOI: 10.1016/j.archoralbio.2010.05.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 05/18/2010] [Accepted: 05/18/2010] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Estrogen deficiency increases bone remodeling leading to increased variability of tissue mineral density (TMD). Due to the functional demands of mastication, alveolar bone around teeth is inherently a highly remodeled region of bone tissue with a highly variable distribution of TMD. This study investigated the effect of estrogen deficiency on the TMD distribution of alveolar bone. DESIGN Using three-dimensional micro-computed tomography images of sham surgery (Sham) and ovariectomized (OVX) rat mandible sections, alveolar bone region (AB) and control bone region (CB) of interest were isolated. Based on histograms of gray levels equivalent to TMD values, mean (Mean), standard deviation (SD) and coefficient of variation (COV=SD/Mean) were computed. Fifth and 95th percentile gray level values were also obtained (Low(5) and High(5), respectively). Absolute value of percentage (%) differences of the gray level parameters between AB and CB regions were computed. RESULTS Both SD and COV were significantly higher in AB region than those in CB region for all specimens of both Sham and OVX groups (p<0.001). The mean values of % differences for SD were moderately higher (p<0.073) and those for COV and Low(5) were significantly higher for the OVX group than for the Sham group (p<0.04). CONCLUSIONS Higher variability of mineralization observed in AB of OVX group indicates that estrogen deficiency amplifies the active bone remodeling of AB already present due to the mastication. These findings provide an insight that the increased variability of TMD induced by estrogen deficiency may compromise the mechanical stability of the tooth-bearing alveolar bone.
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Affiliation(s)
- Matthew S. Ames
- College of Dentistry, Division of Orthodontics, The Ohio State University, Columbus, Ohio, USA
| | - Semi Hong
- College of Dentistry, Division of Orthodontics, The Ohio State University, Columbus, Ohio, USA
| | - Hye Ri Lee
- College of Dentistry, Division of Orthodontics, The Ohio State University, Columbus, Ohio, USA
| | - Henry W. Fields
- College of Dentistry, Division of Orthodontics, The Ohio State University, Columbus, Ohio, USA
| | - William M. Johnston
- College of Dentistry, Division of Restorative and Prosthetic Dentistry, The Ohio State University, Columbus, Ohio, USA
| | - Do-Gyoon Kim
- College of Dentistry, Division of Orthodontics, The Ohio State University, Columbus, Ohio, USA
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Abstract
OBJECTIVES - To test the effect of bisphosphonate (BP) treatment for up to 3 years on bone necrosis and osteocyte death in the mandible using a canine model. MATERIALS AND METHODS - Dogs were treated with clinical doses of oral alendronate (ALN, 0.2 or 1.0 mg/kg/day) for 1 or 3 years. In a separate study, dogs were treated with i.v. zoledronate (ZOL) at 0.06 mg/kg/day for 6 months. En bloc staining was used to identify necrotic areas in the mandible; viable osteocytes were identified using lactate dehydrogenase. RESULTS - None of the treatments was associated with exposed bone, but 17-25% of dogs treated for 1 year and 25-33% of dogs treated for 3 years with ALN showed pockets of dead bone. Necrotic areas had no viable osteocytes and were void of patent canaliculi. No control animals demonstrated necrotic bone. ZOL treatment for 6 months was associated with osteocyte death greater than that seen in animals treated with ALN or saline. It is not clear whether osteocyte death occurs because of direct toxic effects of BPs, or because suppressed remodelling fails to renew areas that naturally undergo cell death. Necrotic areas are also associated with bone other than the mandible, e.g. the rib, which normally undergo high rates of remodelling. CONCLUSIONS - Reduced remodelling rate using BPs may contribute to the pathogenesis of bone matrix necrosis. The development of an animal model that mimics important aspects of BP-related osteonecrosis of the jaw is important to understanding the pathogenesis of osteonecrosis.
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Affiliation(s)
- D B Burr
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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Current World Literature. Curr Opin Pulm Med 2009; 15:521-7. [DOI: 10.1097/mcp.0b013e3283304c7b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Huja SS, Fernandez SA, Phillips C, Li Y. Zoledronic acid decreases bone formation without causing osteocyte death in mice. Arch Oral Biol 2009; 54:851-6. [PMID: 19591974 DOI: 10.1016/j.archoralbio.2009.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 05/11/2009] [Accepted: 06/02/2009] [Indexed: 11/17/2022]
Abstract
Bisphosphonates have been associated with osteonecrosis of the jaw. The purpose of this study was to examine the effect of a potent bisphosphonate, zoledronic acid (ZA) on osteocyte viability and bone formation. Ten experimental C57BL/6 mice were administered ZA (0.1 mg/kg-i.p.) weekly for 9 weeks while four control mice did not receive the drug. A pair of calcein (30 mg/kg) labels was administered 10 and 3 days prior to sacrifice of the 34-week-old mice. Fresh mandibular and femoral sections were obtained to evaluate osteocyte viability using a lactate dehydrogenase (LDH) assay. In addition, sections from the femur, mandible and maxilla were prepared for standard histomorphometry. The operator was blinded for data collection to eliminate bias. Data on necrotic area/total bone area from the LDH sections were collected. In addition, standard histomorphometric variables including bone formation rate were calculated. Mixed models were used to analyse data. The osteocytes were overwhelmingly viable and no necrotic areas were detected in the mandible and femur of both groups. ZA was not directly cytotoxic to the mouse osteocytes. There was suppression in indices of bone formation at all skeletal sites of the ZA group compared to the control group. While ZA administration in mice does not produce necrotic osteocytes, it severely suppresses bone formation. Such reductions can have a profound effect on bone healing.
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Affiliation(s)
- S S Huja
- Division of Orthodontics, College of Dentistry, The Ohio State University, 305 W. 12th St., Columbus, OH 43210, USA.
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