Endospanin Is a Candidate for Regulating Leptin Sensitivity

The hypothesis advanced is that endospanin, a highly conserved vesicle traffic protein in vertebrates, regulates leptin sensitivity in bone signaling. The effects of leptin on bones are well-studied but without consensus on whether the increases in leptin signaling stimulate bone gain or loss. The bone response may depend on leptin sensitivity, and endospanin is an established modulator of leptin sensitivity. An argument is advanced to develop zebrafish models for specific leptin signaling pathways. Zebrafish have well-developed molecular tools (e.g., CRISPR) and the advantage of non-destructive sampling of bones in the form of scales. Using these tools, experiments are described to substantiate the role of endospanin in zebrafish bone dynamics.

The Influence of Storage in Saline or Irradiation by Ultraviolet on Implant Hydrophilicity and Osseointegration: An Experimental Study in Rabbits

Storage in aqueous solution or ultraviolet (UV) irradiation can re t ain or regain the hydrophilicity of titanium implant surface. In this study, t hree types of commercial titanium implants were used : ZBL (ZDI Bone L evel ® ), CEL (C-tech Esthetic Line ® ) , and modSLA (Straumann SLActive ® ). ZBL and CEL implants were treated with UV irradiation for 4 h. Surface characterization of the four groups (ZBL, ZBL-UV, CEL-UV, modSLA) was evaluated by scanning electron microscopy and contact angle measurements. The in vivo bone response was evaluated by removal torque (RTQ) tests and histomorphometric analysis at 3, 6 , and 12 weeks post-implantation. A total of 144 implants and 36 rabbits were used for experiments according to a previously established randomization sequence. The ZBL-UV, CEL-UV , andmodSLA groups were hydrophilic, and nanostructures were observed on the modSLA implant surface.ModSLA achieved better RTQ value than ZBL at 12 weeks ( p <0.05). For histomorphometric analysis, ZBL-UV and CEL-UV implants showed higher bone area values in the cancellous bone zone at 6 weeks than did modSLA and ZBL implants ( p <0.05).In the cortical bone zone, all groups showed comparable bone-to-implant contact at all healing time points ( p >0.05).Both storage in saline and UV irradiation could retain or provoke hydr o philic surfaces and improve osseointegration. Compared to storage in saline, UV irradiation displayed slight advantages in promoting new bone formation in cancellous bone zone at an early stage.

Chronic plantar heel pain modifies associations of ankle plantarflexor strength and body mass index with calcaneal bone density and microarchitecture

Chronic plantar heel pain (CPHP) is associated with calcaneal bone spurs, but its associations with other calcaneal bone features are unknown. This study therefore aimed to determine associations between having CPHP and bone density and microarchitecture of the calcaneus. We assessed 220 participants with CPHP and 100 age- and sex-matched population-based controls. Trabecular bone density, thickness, separation and number, BV/TV, and cortical density, thickness and area were measured using a Scanco Xtreme1 HR-pQCT scanner at a plantar and mid-calcaneal site. Clinical, physical activity and disease history data were also collected. Associations with bone outcomes were assessed using multivariable linear regression adjusting for age, sex, physical activity, BMI and ankle plantarflexor strength. We assessed for potential effect modification of CPHP on these covariates using interaction terms. There were univariable associations at the plantar calcaneus where higher trabecular bone density, BV/TV and thickness and lower trabecular separation were associated with CPHP. In multivariable models, having CPHP was not independently associated with any bone outcome, but modified associations of BMI and ankle plantarflexor strength with mid-calcaneal and plantar bone outcomes respectively. Beneficial associations of BMI with mid-calcaneal trabecular density (BMI-case interaction standardised X/unstandardised Y beta -10.8(mgHA/cm3) (se 4.6), thickness -0.002(mm) (se 0.001) and BV/TV -0.009(%) (se 0.004) were reduced in people with CPHP. Beneficial associations of ankle plantarflexor strength with plantar trabecular density (ankle plantarflexor strength -case interaction -11.9(mgHA/cm3) (se 4.4)), thickness -0.003(mm) (se 0.001), separation -0.003(mm) (se 0.001) and BV/TV -0.010(%) (se 0.004) were also reduced. CPHP may have consequences for calcaneal bone density and microarchitecture by modifying associations of BMI and ankle plantarflexor strength with calcaneal bone outcomes. The reasons for these case-control differences are uncertain but could include a bone response to entheseal stress, altered loading habits and/or pain mechanisms. Confirmation with longitudinal study is required.

Micro-CT Study of Mongolian Gerbil Humeral Bone After Prolonged Spaceflight Based on a New Algorithm for Delimitation of Long-Bone Regions

The Mongolian gerbil displays unique physiological and anatomical features that make this species an attractive object for biological experiments in space. However, until recently, the Mongolian gerbil has remained a novel, mostly unstudied animal model in investigating bone loss in weightlessness (G0). After 12 days of orbital Foton-M3 mission, the humerus of Mongolian gerbils has been studied here via micro-computed tomography (micro-CT) to quantify bone morphometric parameters. The samples from the flight group, delayed synchronous ground-control group, and basal control group were investigated, and main morphometric parameters were reported in the article. The accurate selection of a region of interest is an essential step for a correct assessment of bone parameters. We proposed a new, easy and efficient method for delimiting the bone’s basic regions in the humerus. It is based on quantitative estimation of X-ray attenuation in the cortical bone as a function of humerus bone length. The micro-CT analysis of the basic bone regions revealed a difference in bone morphometric parameters between the flight and control gerbils. The most significant bone loss was observed in the cortical part of the proximal humeral zone in the flight group. No statistically significant changes of volume fraction in the cancellous tissue of proximal and distal epiphyses and metaphyses were observed. A statistically significant increase in both cancellous bone volume and bone X-ray attenuation in the flight group was detected in the proximal part of the diaphyses. We assume that enhanced calcium deposition in the diaphyseal cancellous tissue occurred due to a bone response to G0 conditions.

Bone Response in vivo of Ti-45Zr Alloy as Dental Implant Material

The full text of this preprint has been withdrawn by the authors due to author disagreement with the posting of the preprint. Therefore, the authors do not wish this work to be cited as a reference. Questions should be directed to the corresponding author.

Identification of Bone Density Changes Applying Impedance Spectroscopy with a Piezo-Device Coupled to a Human Tooth

Bone tissue is a calcium deposit and supporting structure of the human body, it is exposed to several pathologies that modify its mineral content. To determine these changes, different diagnostic procedures are performed with techniques using invasive ionizing radiation, which are limited by the negative effects in the long term on human health. A methodology is explored that could be applicable in the diagnosis of pathologic variations in bone mineral density, using structural monitoring tools. The proposed technique estimates changes in bone conditions by applying impedance spectroscopy with a tooth-borne piezo-device. Bone-tooth samples were prepared to simulate a section of maxillary bone and subsequently treated with chemical agents, simulating pathologic decalcification. The piezo-device is inserted in the slot of an orthodontic bracket, previously bonded to the crown of the tooth, in order to transmit vibration to surrounding bone. The variations in bone micro-architecture were computed by image processing analyzed with samples prepared in transparent resin, allowing the measurement of morphometry before and after the induced changes in mineral content. Using vibrational bone response, impedance measurements allowed to observe the variations in bone mass as the samples were progressively decalcified. In the 5-50kHz spectrum, it was demonstrated the sensitivity of the electro-mechanical impedance during the bone alteration procedure since the electrical resistance signals of the piezo-device consistently changed in the frequency spectrum (5-50kHz). The piezo-device shows to be sensitive to the changes produced by the bone alterations, which were caused by the stiffness variations made in the sample during the decalcifying. These changes were statistically correlated to demonstrate that in a less invasive way, bone alterations could be monitored from the teeth. This result opens the door to search for a new way to diagnose bone density changes in real applications.

Osseointegration of Sandblasted and Acid-Etched Implant Surfaces. A Histological and Histomorphometric Study in the Rabbit

Titanium surface is an important factor in achieving osseointegration during the early wound healing of dental implants in alveolar bone. The purpose of this study was to evaluate sandblasted-etched surface implants to investigate the osseointegration. In the present study, we used two different types of sandblasted-etched surface implants, an SLA™ surface and a Nanoblast Plus™ surface. Roughness and chemical composition were evaluated by a white light interferometer microscope and X-ray photoelectron spectroscopy, respectively. The SLA™ surface exhibited the higher values (Ra 3.05 μm) of rugosity compared to the Nanoblast Plus™ surface (Ra 1.78 μm). Both types of implants were inserted in the femoral condyles of ten New Zealand white rabbits. After 12 weeks, histological and histomorphometric analysis was performed. All the implants were osseointegrated and no signs of infection were observed. Histomorphometric analysis revealed that the bone–implant contact % (BIC) ratio was similar around the SLA™ implants (63.74 ± 13.61) than around the Nanoblast Plus™ implants (62.83 ± 9.91). Both implant surfaces demonstrated a favorable bone response, confirming the relevance of the sandblasted-etched surface on implant osseointegration.

Bone Response to Conventional Titanium Implants and New Zirconia Implants Produced by Additive Manufacturing

The aim of the present study was to evaluate the in vivo bone response to an additively manufactured zirconia surface compared to osseointegration into titanium (Ti) surfaces. Scanning electron microscopy, confocal laser scanning microscopy, and electron spectroscopy for chemical analysis were performed to assess the surface characteristics of implant specimens. For the in vivo evaluation, eight Ti implants and eight 3D-printed zirconia implants were used. The surface of four Ti implants was sandblasted, large-grit, and acid-etched (Ti-SLA group), while those of the other four Ti implants were left untreated (Ti-turned group). The zirconia implants had no further surface modification. Implants were placed into the tibiae of four rabbits; two received the Ti-SLA and zirconia implants and the other two received Ti-turned and zirconia implants. The experimental animals were sacrificed after four weeks of surgery, and the undecalcified microscopic slides were prepared. The bone–implant interface was analyzed by histomorphometry to evaluate the bone response. The degree of surface roughness showed that Ti-SLA was the highest, followed by zirconia and Ti-turned surfaces. The 3D-printed zirconia surface showed similar bone-to-implant contact to the Ti-turned surface, and Ti-SLA had the most bone-to-implant contact. The additively manufactured zirconia implant surface is biocompatible with respect to osseointegration compared to the commercially pure Ti surface.

The Role of Biomaterials and Biocompatible Materials in Implant-Supported Dental Prosthesis

The dental implant is one of the appropriate instances of the different dental materials and their application, which is the combined procedure of technology and science in physics, biomechanics, and surface chemistry from macroscale to nanoscale surface engineering and manufactured technologies. In recent decades, biomaterials in implant therapy promote bone response and biomechanical ability, which is long-term from surgical equipment to final prosthetic restoration. Biomaterials have a crucial role in rehabilitating the damaged structure of the tooth and supplying acceptable outcomes correlated with clinical performance. There are some challenges in implantation such as bleeding, mobility, peri-implant infections, and the solution associated with modern strategies which are regarded to biomaterials. Various materials have been known as promising candidates for coatings of dental implants which contain polyhydroxyalkanoates, calcium phosphate, carbon, bisphosphonates, hydroxyapatite, bone stimulating factors, bioactive glass, bioactive ceramics, collagen, chitosan, metal and their alloys, fluoride, and titanium/titanium nitride. It is pivotal that biomaterials should be biodegradable; for example, polyhydroxyalkanoates are biodegradable; also, they do not have bad effects on tissues and cells. Despite this, biomaterials have important roles in prosthetic conditions such as dental pulp regeneration, the healing process, and antibacterial and anti-inflammatory effects. In this review study, the role of biocompatible materials in dental implants is investigated in in vitro and in vivo studies.