Three-Dimensional Static Articulation Accuracy of Virtual Models - Part I: System Trueness and Precision.

PURPOSE: To evaluate the 3D static articulation accuracy of 3 model scanner-CAD systems (Ceramill Map400 [AG], inEos X5 [SIR], Scanner S600 Arti [ZKN]) using a coordinate measuring machine (CMM). Trueness and precision for each system will be reported in Part I. MATERIALS AND METHODS: The master model simulated a single crown opposing a 3-unit fixed dental prosthesis. Five mounted stone cast sets were prepared, and one set was randomly selected. Reference values were obtained by measuring interarch and interocclusal reference features with the CMM. The stone cast set was scanned 5 times consecutively and articulated virtually with each system (3 test groups, n = 5). STL files of the virtual models were measured with CMM software. dRR , dRC , and dRL , represented interarch global distortions at right, central, and left sides, respectively, while dRM , dXM , dYM , and dZM represented interocclusal global and linear distortions between preparations. RESULTS: For trueness values, mean interarch global distortions ranged from 13.1 to 40.3 µm for dRR , -199.0 to -48.1 µm for dRC , and -114.1 to -47.7 µm for dRL . Mean percentage error of interarch distortion did not exceed 0.6%. Mean interocclusal distortions ranged from 16.0 to 117.0 µm for dRM , -33.1 to 101.3 µm for dXM , 32.9 to 49.9 µm for dYM and -32.0 to 133.1 µm for dZM. ANOVA of trueness found statistically significant differences for dRC , dRL , dRM , dXM , and dZM . For precision values, absolute mean difference between the 10 superimposition combinations ranged from 25.3 to 91.0 µm for dRR , 21.5 to 85.5 µm for dRC , 24.8 to 70.0 µm for dRL . Absolute mean difference ranged from 49.9 to 66.1 µm for dRM , 20.7 to 92.1 µm for dXM , 86.8 to 96.0 µm for dYM , and 36.5 to 100.0 µm for dZM . ANOVA of precision of all test groups found statistically significant differences for dRR , dRC , dRL , dXM and dZM , and the SIR group was the least precise. CONCLUSION: The overall interarch global distortion of all three model scanner-CAD systems was low and did not exceed 0.6%. Variations in scanner technology, virtual articulation algorithm, and use of physical articulators contributed to the differences in distortion observed among all three groups.

Three-Dimensional Static Articulation Accuracy of Virtual Models-Part II: Effect of Model Scanner-CAD Systems and Articulation Method.

PURPOSE: Accurate maxillomandibular relationship transfer is important for CAD/CAM prostheses. This study compared the 3D-accuracy of virtual model static articulation in three laboratory scanner-CAD systems (Ceramill Map400 [AG], inEos X5 [SIR], Scanner S600 Arti [ZKN]) using two virtual articulation methods: mounted models (MO), interocclusal record (IR). MATERIALS AND METHODS: The master model simulated a single crown opposing a 3-unit fixed partial denture. Reference values were obtained by measuring interarch and interocclusal reference features with a coordinate measuring machine (CMM). MO group stone casts were articulator-mounted with acrylic resin bite registrations while IR group casts were hand-articulated with poly(vinyl siloxane) bite registrations. Five test model sets were scanned and articulated virtually with each system (6 test groups, 15 data sets). STL files of the virtual models were measured with CMM software. dRR , dRC , and dRL , represented interarch global distortions at right, central, and left sides, respectively, while dRM , dXM , dYM , and dZM represented interocclusal global and linear distortions between preparations. RESULTS: Mean interarch 3D distortion ranged from -348.7 to 192.2 µm for dRR , -86.3 to 44.1 µm for dRC , and -168.1 to 4.4 µm for dRL . Mean interocclusal distortion ranged from -257.2 to -85.2 µm for dRM , -285.7 to 183.9 µm for dXM , -100.5 to 114.8 µm for dYM , and -269.1 to -50.6 µm for dZM . ANOVA showed that articulation method had significant effect on dRR and dXM , while system had a significant effect on dRR , dRC , dRL , dRM , and dZM . There were significant differences between 6 test groups for dRR, dRL dXM , and dZM . dRR and dXM were significantly greater in AG-IR, and this was significantly different from SIR-IR, ZKN-IR, and all MO groups. CONCLUSIONS: Interarch and interocclusal distances increased in MO groups, while they decreased in IR groups. AG-IR had the greatest interarch distortion as well as interocclusal superior-inferior distortion. The other groups performed similarly to each other, and the overall interarch distortion did not exceed 0.7%. In these systems and articulation methods, interocclusal distortions may result in hyper- or infra-occluded prostheses.

Simvastatin prevents alveolar bone loss in an experimental rat model of periodontitis after ovariectomy.

BACKGROUND: Periodontitis is an inflammatory disease characterized by the loss of connective tissue and alveolar bone. There is an increasing evidence that periodontitis is associated with a number of chronic disease, including osteoporosis. Periodontitis and osteoporosis are both bone destructive diseases and of high prevalence in adult population. Osteoporosis could increase some inflammatory factors that also participate in the progression of periodontitis, so as to facilitate the alveolar bone resorption. Simvastatin, specific inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme reductase, is of pleiotropic effects including anti-catabolic and anabolic effect on bone metabolism. This study aimed to explore the local and systemic effect of simvastatin on maxillary in rats with both osteoporosis and periodontitis. METHODS: Thirty-six 4-month-old female Sprague Dawley rats were randomly assigned to six groups: sham group, ligature group, ovariectomized (OVX) + ligature group, local simvastatin administration to OVX + ligature rats (local simvastatin group), oral simvastatin administration to OVX + ligature rats (oral simvastatin group), local and oral simvastatin administration to OVX + ligature rats (L&O simvastatin group). One month after OVX, ligatures were placed on the maxillary first (M1) and second molars (M2) for 4 weeks on all rats except those in the sham group, followed by simvastatin treatment for 2 months. The maxillae, serum, and femurs were collected for further examination including micro-computed (micro-CT) tomography, hematoxylin and eosin (H&E) staining, tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assays (ELISA), and the three-point bending test. RESULTS: Local simvastatin administration increased alveolar crest height and prevented local alveolar bone loss without alteration of systemic bone loss. Oral administration prevented local and systemic bone loss with no effect on alveolar crest height. CONCLUSIONS: Our results indicate that simvastatin has the potential of promoting bone formation and reducing alveolar bone loss in maxillary following ovariectomy (OVX) and ligature placement in rats.

Sanguinarine inhibits osteoclast formation and bone resorption via suppressing RANKL-induced activation of NF-κB and ERK signaling pathways.

Sanguinarine is a natural plant extract that has been supplemented in a number of gingival health products to suppress the growth of dental plaque. However, whether sanguinarine has any effect on teeth and alveolar bone health is still unclear. In this study, we demonstrated for the first time that sanguinarine could suppress osteoclastic bone resorption and osteoclast formation in a dose-dependent manner. Sanguinarine diminished the expression of osteoclast marker genes, including TRAP, cathepsin K, calcitonin receptor, DC-STAMP, V-ATPase d2, NFATc1 and c-fos. Further investigation revealed that sanguinarine attenuated RANKL-mediated IκBα phosphorylation and degradation, leading to the impairment of NF-κB signaling pathway during osteoclast differentiation. In addition, sanguinarine also affected the ERK signaling pathway by inhibiting RANKL-induced ERK phosphorylation. Collectively, this study suggested that sanguinarine has protective effects on teeth and alveolar bone health.

The structural pathology for hypophosphatasia caused by malfunctional tissue non-specific alkaline phosphatase.

Hypophosphatasia (HPP) is a metabolic bone disease that manifests as developmental abnormalities in bone and dental tissues. HPP patients exhibit hypo-mineralization and osteopenia due to the deficiency or malfunction of tissue non-specific alkaline phosphatase (TNAP), which catalyzes the hydrolysis of phosphate-containing molecules outside the cells, promoting the deposition of hydroxyapatite in the extracellular matrix. Despite the identification of hundreds of pathogenic TNAP mutations, the detailed molecular pathology of HPP remains unclear. Here, to address this issue, we determine the crystal structures of human TNAP at near-atomic resolution and map the major pathogenic mutations onto the structure. Our study reveals an unexpected octameric architecture for TNAP, which is generated by the tetramerization of dimeric TNAPs, potentially stabilizing the TNAPs in the extracellular environments. Moreover, we use cryo-electron microscopy to demonstrate that the TNAP agonist antibody (JTALP001) forms a stable complex with TNAP by binding to the octameric interface. The administration of JTALP001 enhances osteoblast mineralization and promoted recombinant TNAP-rescued mineralization in TNAP knockout osteoblasts. Our findings elucidate the structural pathology of HPP and highlight the therapeutic potential of the TNAP agonist antibody for osteoblast-associated bone disorders.

Ano5 modulates calcium signaling during bone homeostasis in gnathodiaphyseal dysplasia.

ANO5 encodes transmembrane protein 16E (TMEM16E), an intracellular calcium-activated chloride channel in the endoplasmic reticulum. Mutations in ANO5 are associated with gnathodiaphyseal dysplasia (GDD), a skeletal disorder causing the jaw deformity and long bone fractures. However, the coordinated mechanism by which ANO5 mediates bone homeostasis in GDD remains poorly defined. Here, we show that ablation of Ano5 reduced intracellular calcium transients, leading to defects in osteogenesis and osteoclastogenesis and thus bone dysplasia. We found a causative de novo ANO5 frameshift insertion mutation (p.L370_A371insDYWRLNSTCL) in a GDD family with osteopenia, accompanied by a decrease in TMEM16E expression and impaired RANKL-induced intracellular calcium ([Ca2+]i) oscillations in osteoclasts. Moreover, using Ano5 knockout (KO) mice, we found that they exhibited low bone volume, abnormal calcium deposits, and defective osteoblast and osteoclast differentiation. We also showed that Ano5 deletion in mice significantly diminished [Ca2+]i oscillations in both osteoblasts and osteoclasts, which resulted in reduced WNT/ß-Catenin and RANKL-NFATc1 signaling, respectively. Osteoanabolic treatment of parathyroid hormone was effective in enhancing bone strength in Ano5 KO mice. Consequently, these data demonstrate that Ano5 positively modulates bone homeostasis via calcium signaling in GDD.

Bis­enoxacin blocks alveolar bone resorption in rats with ovariectomy­induced osteoporosis.

Postmenopausal osteoporosis is a common systemic skeletal disease that is associated with estrogen­deficiency. Bone loss associated with bisphosphonates therapy can increase the risk of developing oral osteonecrosis. Recent studies have indicated that enoxacin may inhibit osteoclast formation and bone resorption via a different mechanism from that of bisphosphonates. Therefore, the authors hypothesized that the use of an enoxacin such as bis­enoxacin (BE) in association with bisphosphonates may be effective in the treatment of postmenopausal osteoporosis­associated alveolar bone resorption and reduce the risk of oral osteonecrosis by allowing the dose of bisphosphonates to be reduced. A total of 30 6­month­old female Sprague­Dawley rats were randomly assigned to five groups: The Sham, Vehicle, zoledronic acid (ZOL), low concentrations of BE (BE­L) and high concentrations of BE (BE­H) groups. The results demonstrated that the ZOL, BE­L and BE­H groups had an increased bone volume/tissue volume, trabecular thickness, mineral apposition rate, mineralizing surface/bone surface and a decreased trabecular separation when compared with the Vehicle group. The microscopic evaluation of histological sections clearly supported the results of the micro­computed tomography. The number of tartrate­resistant acid phosphatase­positive osteoclasts was markedly decreased in the ZOL, BE­L and BE­H groups, indicating that BE may inhibit osteoclast formation. The anti­resorptive effect in the BE­H group was close to or better than that exhibited by the ZOL group; however, this effect was poorer in the BE­L group. In conclusion, BE has the potential to block alveolar bone resorption resulting from ovariectomy­induced osteoporosis in rats in a dose­dependent manner.

Periosteum Extracellular-Matrix-Mediated Acellular Mineralization during Bone Formation.

Cell-mediated mineralization is essential for bone formation and regeneration. In this study, it is proven that extracellular matrix (ECM) of decellularized periosteum can play an initiative and independent role in bone-like apatite formation. Using decellularized periosteum scaffold, it is revealed that ECM scaffold itself can promote critical bone defect regeneration and nude mouse ectopic ossification. The natural collagen matrix of decellularized periosteum can serve as a 3D structural template for Ca-P nuclei initiation, controlling the size and orientation of bone-like mineral crystals. The naturally cross-linked and highly ordered 3D fibrillar network of decellularized periosteum not only provides a model for mimicking mineralization in vitro and in vivo to elucidate the important functions of ECM in bone formation and regeneration, but also can be a promising biomaterial for bone tissue engineering and clinical application.

[The relations between dental fluorosis and economic status in Shuicheng, a fluorosis-endemic County in Guizhou province].

OBJECTIVE: To discuss the relations of dental fluorosis and the social economic status in fluorosis-stricken villages where drying the corn by burning coal was prevail. METHODS: A total of 6 fluorosis-endemic villages and one non-endemic village were involved in the study. The general fluorine intake and the concentrations of fluorine in corn, in the pupils' were tested. Dental fluorosis among the pupils was also examen. A individual interview or household questionnaire survey was conducted to probe the economic condition and staple food structure in 600 adults. RESULTS: The fluorosis prevalence was lower in the villages of transportation convenience, higher income, less coal-dried corn intake. There was a declining trend of dental fluorosis in the corresponding age groups (r: 0.912, 0.916; P < 0.05); There was no significant changes in age-specified dental fluorosis in the low income villages. The correlation (r) of corn fluorine concentration and student's age-specified dental fluorosis prevalence and disparity was 0.755 - 0.980 (P < 0.05) and 0.302 - 0.811; The urine fluorine concentrations were 0.811 and 0.915 (P < 0.05). It was assumed that there was a negative correlation between family cash income and the dental fluorosis. CONCLUSIONS: The corn fluorine concentration is closely related to age-specified dental fluorosis. With the economic improvement, taking less coal-burned corn is the one of major factors in reducing the of dental fluorosis in these areas.

Biodegradable and biocompatible high elastic chitosan scaffold is cell-friendly both in vitro and in vivo.

Biodegradable and biocompatible macromolecule chitosan has been favored for a variety of clinical applications. We reported herein the fabrication of a novel chitosan scaffold with high elasticity. This scaffold can be easily compressed and thus enable the insertion of such scaffold into surgical lesions during minimal invasive surgeries. In addition, this novel scaffold can restore its shape when released. We evidenced that this high elastic scaffold has better biocompatibility than traditional chitosan scaffold. Therefore, this new chitosan material might lead to the manufacture of a variety of novel biodegradable biomedical materials and devices.

Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration.

Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases.

Nitidine chloride prevents OVX-induced bone loss via suppressing NFATc1-mediated osteoclast differentiation.

Nitidine chloride (NC), a bioactive alkaloid isolated from Zanthoxylum nitidum, has been used as a herbal ingredient in toothpaste that prevents cavities for decades. It also displays potential antitumor and anti-inflammation properties. However, its anticatabolic effect on bone is not known. We investigated the effect of NC on osteoclastogenesis, bone resorption and RANKL-induced NF-κB and NFATc1 signalling. In mouse-derived bone marrow monocytes (BMMs), NC suppressed RANKL-induced multinucleated tartrate-resistant acid phosphatase (TRAP)-positive osteoclast formation and bone resorption in a dose dependent manner. NC attenuated the expression of osteoclast marker genes including cathepsin K, D2, calcitonin receptor, NFATc1, and TRAP. Further, NC inhibited RANKL-activated NF-κB and NFATc1 signalling pathways. In vivo study revealed that NC abrogated oestrogen deficiency-induced bone loss in ovariectomized mice. Histological analysis showed that the number of osteoclasts was significantly lower in NC-treated groups. Collectively, our data demonstrate that NC suppressed osteoclastogenesis and prevented OVX-induced bone loss by inhibiting RANKL-induced NF-κB and NFATc1 signalling pathways. NC may be a natural and novel treatment for osteoclast-related bone lytic diseases.

Effects of oestrogen deficiency on the alveolar bone of rats with experimental periodontitis.

Periodontitis is an inflammatory disease characterized by loss of connective tissue and alveolar bone, and osteoporosis is a common disease characterized by a systemic impairment of bone mass and microarchitecture. To date, the association between periodontitis and osteoporosis has remained to be fully elucidated. In the present study, an experimental rat model of periodontitis was used to explore the effects of oestrogen deficiency­induced osteoporosis on the maxillary alveolar bone. Forty­four female, six­month­old Sprague­Dawley rats were randomly divided into four groups: Control, ligature, ovariectomized (OVX), and OVX + ligature. One month after ovariectomy, rats in the ligature and OVX + ligature groups received ligatures on their first and second maxillary molars for 1 month. Fluorescent labelling was performed prior to sacrificing the animals. At the end of the experiment, the maxillae and serum were collected and subjected to micro­computed tomography analysis, confocal laser­scanning microscopic observation, Van Gieson's fuchsin staining, tartrate­resistant acid phosphatase staining and ELISA. Ligatures slightly reduced the alveolar bone mineral density (BMD) and bone formation rate, but significantly reduced alveolar crest height (ACH). Ovariectomy reduced the alveolar BMD, impaired the trabecular structure, reduced the bone formation rate and increased the serum levels of bone resorption markers. Animals in the OVX + ligature group exhibited a lower alveolar BMD, a poorer trabecular structure, a reduced ACH, a lower bone formation rate and higher serum levels of bone resorption markers compared with those in the control group. The results of the present study showed that ovariectomy enhanced alveolar bone loss and reduced the ACH of rats with experimental periodontitis. Thus, post­menopausal osteoporosis may influence the progression of periodontitis.

Sclerostin antibody treatment causes greater alveolar crest height and bone mass in an ovariectomized rat model of localized periodontitis.

INTRODUCTION: Periodontitis and osteoporosis are bone destructive diseases with a high prevalence in the adult population. The concomitant presence of osteoporosis may be a risk factor of progression of periodontal destruction. We studied the effect of sclerostin-neutralizing monoclonal antibody (Scl-Ab) on alveolar bone endpoints in an ovariectomized (OVX) rat model of induced experimental periodontitis. METHODS: Sixty female, 4-month-old Sprague-Dawley rats underwent sham operation or bilateral OVX and were left untreated for 2 months. Experimental periodontitis (ligature) was established by placing silk sutures subgingival to the right maxillary first and second molar teeth for 4 weeks, and feeding the rats food and high-sugar drinking water during this period. Thereafter, ligatures were removed and 25mg/kg vehicle or Scl-Ab was administered subcutaneously twice weekly for 6 weeks. Rats were randomized into four groups: (1) Control (Sham+Vehicle), (2) Sham+Ligature+Vehicle, (3) OVX+Ligature+Vehicle, and (4) OVX + Ligature + Scl-Ab. Terminal blood and right maxilla specimens were collected for analyses. RESULTS: Group 3 rats showed lower bone volume fraction (BVF) of alveolar bone with higher bone resorption and lower bone formation than Group 2 rats. Group 4 rats had higher alveolar crest height, as assessed by linear distance of cementoenamel junction to the alveolar bone crest and greater alveolar bone mass using Micro CT, than Group 3 rats. Significantly higher values of mineral apposition rate (MAR) and mineralizing surface/bone surface (MS/BS) were also observed in Group 4 rats by analyzing polychrome sequential labeling data. Increased serum osteocalcin and osteoprotegerin, and deceased serum tartrate-resistant acid phosphatase and CTx-1 illustrate the ability of Scl-Ab to increase alveolar bone mass by enhancing bone formation and decreasing bone resorption in an animal model of estrogen deficiency osteopenia plus periodontitis. CONCLUSION: Scl-Ab could be a potential bone anabolic agent for improving alveolar crest height and higher alveolar bone mass in conditions where alveolar bone loss in periodontitis is compounded by estrogen deficiency osteopenia.

Improved hMSC functions on titanium coatings by type I collagen immobilization.

In this study, type I collagen was fixed onto plasma-sprayed porous titanium coatings by either adsorptive immobilization or covalent immobilization. Surface characterization by scanning electron microscopy (SEM), diffuse reflectance Fourier transform infrared spectroscopy (DR-FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the biochemical modification of the titanium coatings. The immobilizing effects of type I collagen, including variations in the amount and stability of collagen, were investigated using Sirius red staining. A greater amount of collagen was found on the covalently immobilized titanium coating, and higher stability was achieved relative to the absorptive immobilization surface. Human mesenchymal stem cells (hMSCs) were used to evaluate the cytocompatibility of the modified titanium coatings. Type I collagen immobilized on titanium coating led to enhance cell-material interactions and improved hMSC functions, such as attachment, proliferation, and differentiation. Interestingly, covalently immobilized collagen on titanium coating showed a greater capability to regulate the osteogenic activity of hMSCs than did absorbed collagen, which was explained in terms of the increased amount and higher stability of the covalently linked collagen. The type I collagen covalently immobilized titanium coatings with improved biological function may exhibit better osteointegration in clinical application.

Immobilization of hyaluronic acid on plasma-sprayed porous titanium coatings for improving biological properties.

In the present study, hyaluronic acid (HyA) was covalently immobilized onto titanium coatings to improve their biological properties. Diffuse reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were employed to characterize the HyA-modified titanium coating. HyA-modified titanium coatings possess better cell-material interaction, and human mesenchymal stem cells present good adhesive morphologies on the surface of TC-AAH. The results of subsequent cellular evaluation showed that the immobilization of HyA on titanium coatings could improve hMSC attachment, proliferation, and differentiation. In vivo evaluation of implants in rabbit femur condyle defect model showed improvements of early osseointegration and bone-to-implant contact of TC-AAH. In conclusion, immobilization of HyA could improve biological properties of titanium coatings.