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Titanium (Ti) and Ti alloys possess extensive applications in the medical field due to their non-toxic, biocompatible, and antibacterial properties. This study investigates the biocompatibility enhancement of a Ti-based alloy, Ti-6Al-4V, through a multi-step process involving cathodic arc ion plating of a TiZrTa thin film and subsequent laser-textured oxidation (LTO). LTO treatment produced a structured microtopography with regular groove patterns, including straight lines (L-s), circles (L-c), and checkboards (L-ch), resulting in surface oxidation and the formation of various oxides on the TiZrTa coating. Microstructure analyses revealed substantial alterations in surface topography induced by laser texturing. Antibacterial assessments against Staphylococcus aureus (S. aureus) showed that the films with LTO treatment did not exhibit significant advantages after 12 or 24 h of coculture because the laser-textured portions consisted of a combination of the film and the substrate, and the antibacterial effect was not obvious. Coatings with LTO treatment significantly improved L-929 mouse fibroblasts cell viability at 48 h, particularly for samples with a 50 μm spacing of straight and circular patterns (L-s and L-c). After two weeks of MG-63 human osteosarcoma cell culture, the viability of all samples reached similar levels. It suggested that the TiZrTa-coated Ti-6Al-4V exhibited good biocompatibility with both cells. This study contributed to the understanding of surface modification techniques for enhancing the biocompatibility of Ti-based alloys in biomedical applications. • A TiZrTa thin film with LTO treatment was applied onto Ti-6Al-4V alloys. • LTO produced regular groove patterns and resulted in superior hydrophilicity. • LTO-treated thin films did not have obvious antibacterial improvement of S. aureus. • LTO-treated thin films improved the cell viability of both L-929 and MG-63 cells. [ABSTRACT FROM AUTHOR]

Residual alveolar ridge resorption often occurs after tooth extraction, which causes issues requiring further prothesis rehabilitation. A treatment concept referred to as all-on-four, involving fixed dentures supported with four implants, was recently developed. The current study aimed to determine the effect of changing bone atrophy and implant length in all-on-four treatments on stress and strain in the surrounding bone of the implant. A three-dimensional finite element method was used in this research. The stress analysis was conducted with von Mises stress values. Two types of synthetic jawbone models with mild and moderate atrophy were used. Furthermore, two different implant lengths with a similar implant design and diameter were selected, and they were classified into eight models. Then, the bone model was assessed via a computed tomography (CT) scan and was transformed into a virtual model in Geomagic and SolidWorks with implant rebuilding. After modifying bone atrophy, the von Mises stresses in the surrounding bone of the implant were as follows: mild type 2 < mild type 3 < moderate type 3 < moderate type 4. The bone quantity change rate increased more than when bone conditions were limited. Compared with changes in implant lengths, the stresses in the peri-implant surrounding bone were generally higher in the 9 mm implant length group than in the 11.5 mm group. However, the results did not significantly differ. In conclusion, the von Mises stress and strain increased in the models with moderate atrophy and low-density trabecular bone. Hence, bone atrophy and its presurgical diagnosis in long-term implant prognosis are crucial. [ABSTRACT FROM AUTHOR]

Objective: The study objective was to investigate four common occlusal modes by using the finite element (FE) method and to conduct a biomechanical analysis of the periodontal ligament (PDL) and surrounding bone when orthodontic force is applied. Materials and methods: A complete mandibular FE model including teeth and the PDL was established on the basis of cone-beam computed tomography images of an artificial mandible. In the FE model, the left and right mandibular first premolars were not modeled because both canines required distal movement. In addition, four occlusal modes were simulated: incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), and right group function (RGF). The effects of these four occlusal modes on the von Mises stress and strain of the canine PDLs and bone were analyzed. Results: Occlusal mode strongly influenced the distribution and value of von Mises strain in the canine PDLs. The maximum von Mises strain values on the canine PDLs were 0.396, 1.811, 0.398, and 1.121 for INC, ICP, RMOL, and RGF, respectively. The four occlusal modes had smaller effects on strain distribution in the cortical bone, cancellous bone, and miniscrews. Conclusion: Occlusal mode strongly influenced von Mises strain on the canine PDLs when orthodontic force was applied. Clinical relevance: When an FE model is used to analyze the biomechanical behavior of orthodontic treatments, the effect of muscle forces caused by occlusion must be considered. [ABSTRACT FROM AUTHOR]

Titanium and titanium alloy materials are often made as medical implants. Surface properties of titanium medical implants play decisive roles for antibacterial and biological response and tissue biocompatibility. In this study, cathode arc evaporation (CAE) technology was used to deposit TiNb–Zr–Ta and nitrogen-doped TiNb–Zr–Ta coatings with nanostructures on the Ti–6Al–4V dental abutment screws. The deposited coatings were then oxidized at high temperature to produce different oxides on the surface of the coatings. The mechanical properties, antibacterial properties and biocompatibilities of the coatings were analyzed. The effect of coatings on the abutment screw loosening and removal torque between the abutment screw and the pure titanium implant fixture was studied by removal torque measurement. In addition, Staphylococcus aureus (S. aureus) was used for evaluating the antibacterial properties of coatings, and mouse fibroblasts (L929) were used for ISO 10993-5 cytotoxicity analyses to determine whether it had good biocompatibility. Nanolayered structures and multiphases of polycrystalline TiNb–Zr–Ta were obtained by co-deposition of Ta, Zr and TiNb. When small content of N was introduced, the TiNb–Zr–Ta(N) showed a polycrystalline TiNb–Zr–Ta where N atoms entered the metallic lattice at interstitial sites. After oxidation, oxide phases of Ta 2 O 5 , TiO 2 , Nb 2 O 5 and ZrO 2 were formed on the surface of TiNb–Zr–Ta and TiNb–Zr–Ta(N). Ta 2 O 5 was obtained on the surface of the coating prior to other oxides such as TiO 2 , Nb 2 O 5 and ZrO 2. The deposited TiNb–Zr–Ta and TiNb–Zr–Ta(N) coatings had high contact angle and exhibited a hydrophobic feature, while the annealed TiNb–Zr–Ta–O and TiNb–Zr–Ta(N)–O showed hydrophilicity. The deposited TiNb–Zr–Ta had similar hardness and Young's modulus values to that of the uncoated Ti–6Al–4V. When N was doped, the TiNb–Zr–Ta(N) had the highest hardness and Young's modulus. The hardness of the annealed TiNb–Zr–Ta(N) coating only decreased slightly due to the small oxide layer of ∼140 nm. Compared with the uncoated Ti–6Al–4V, TiNb–Zr–Ta serial coatings deposited on abutment screws had higher removal torques, which prevented the abutment screw of dental implant from loosening after long-term use. The biocompatibility of TiNb–Zr–Ta serial coatings was similar to that of the uncoated Ti–6Al–4V. In addition, the oxidized TiNb–Zr–Ta and TiNb–Zr–Ta(N) coatings had excellent antibacterial properties. It is speculated that the resulting Ta 2 O 5 of both coatings may inhibit bacterial growth and improve the antibacterial effect. Based on the above advantages, the TiNb–Zr–Ta serial coatings are expected to have the potential to be applied to biomedical implants. • TiNb–Zr–Ta and nitrogen-doped TiNb–Zr–Ta coatings were obtained by co-deposition of Ta, Zr and TiNb targets. • After annealing, oxide phases were formed on the surface of TiNb–Zr–Ta and nitrogen-doped TiNb–Zr–Ta. • All coatings fabricated provided good biocompatibility similar to Ti–6Al–4V alloy. • Annealed coatings with Ta 2 O 5 on the surface possessed good antibacterial effect. • The highest removal torque was obtained for the abutment screw coated with TiNbZrTa. [ABSTRACT FROM AUTHOR]

Background Dental implants have become reliable and predictable tools for treating missing teeth. The survival rate of dental implants is markedly influenced by the host bone quality and quantity of the jawbone. A better host bone provides higher initial stability of the dental implant, resulting in better osseointegration and a higher success rate. Host bone quality and quantity are determined by the crestal cortical bone thickness and inner cancellous bone density. Objective The purpose of this study was to determine the crestal cortical bone thickness at dental implant sites in different regions of the jawbone through the use of dental cone-beam computed tomographic (CBCT) images. Materials and Methods A total of 661 dental implant sites (81 in the anterior mandible, 122 in the anterior maxilla, 224 in the posterior mandible, and 234 in the posterior maxilla) were obtained from the jawbones of 173 humans. The data were subjected to statistical analysis to determine any correlation between crestal cortical bone thicknesses and jawbone regions using one-way analysis of variance with Tukey's post-test. Results The crestal cortical bone thicknesses at dental implant sites in the four regions decreased in the following order: posterior mandible (1.07 ± 0.47 mm, mean ± SD) >anterior mandible (0.99 ± 0.36 mm) >anterior maxilla (0.82 ± 0.30 mm) >posterior maxilla (0.75 ± 0.35 mm). Conclusion The dental CBCT data demonstrate that crestal cortical bone thickness varies markedly between dental implant sites in the four regions of the jawbone. [ABSTRACT FROM AUTHOR]

A cathodic-arc evaporation system with plasma-enhanced duct equipment was used to deposit TiZrN, TiZrCN, and TiZr/a-C coatings. Reactive gases (N 2 and C 2 H 2 ) activated by the Ti and Zr plasma in the evaporation process was used to deposit the TiZrCN and TiZr/a-C coatings with different C and nitrogen contents. The crystalline structures and bonding states of coatings were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The microbial activity of the coatings was evaluated against Staphylococcus aureus (Gram-positive bacteria) and Actinobacillus actinomycetemcomitans (Gram-negative bacteria) by in vitro antibacterial analysis using a fluorescence staining method employing SYTO9 and a bacterial-viability test on an agar plate. The cell compatibility and morphology related to CCD-966SK cell-line human skin fibroblast cells on the coated samples were also determined using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, reverse-transcriptase-polymerase chain reaction, and scanning electron microscopy. The results suggest that the TiZrCN coatings not only possess better antibacterial performance than TiZrN and TiZr/a-C coatings but also maintain good compatibility with human skin fibroblast cells. [ABSTRACT FROM AUTHOR]

The surface characteristics of biomaterials play an important role in their interaction with biological systems. Tantalum (Ta) oxides and their coatings have been proved to increase their applications in the biomedical fields such as medical devices and dental implants by improving their osseointegration and corrosion resistance. In this study, Ta and amorphous tantalum oxide coatings were deposited by using magnetron sputtering. A hydrophilic crystalline β-Ta 2 O 5 coating was obtained by rapid thermal annealing of the deposited tantalum oxide coating at 700 °C. In this study, Staphylococcus aureus and Actinobacillus actinomycetemcomitans ( A. actinomycetemcomitans ) are Gram-positive and Gram-negative bacteria, respectively, that exhibit physiological commensalism on the human skin and oral areas. Both bacteria were chosen as the model for in vitro anti-bacterial analyses by a fluorescence staining method employing Syto9. The cytocompatibility of human skin fibroblast cells (CCD-966SK) on the coatings was also determined using an MTT assay. It showed that the amorphous tantalum oxide coatings possessed good antibacterial performance, while the hydrophilic crystalline tantalum oxide coatings exhibited outperformed human skin fibroblast cellular biocompatibility. [ABSTRACT FROM AUTHOR]

Objective: Small-diameter implants have been available since the 1990s, but few studies have analyzed their mechanical properties. This study evaluated the effects of the implant material and the implant-abutment connection designs on the primary stability and the marginal bone strain of small-diameter implant subject to immediate loading. Materials and methods: Insertion torque value (ITV), implant stability quotient (ISQ), and Periotest value (PTV) of three implant systems with four parameters (titanium, titanium alloy, internal and external hexagon connections) were measured after placing implants into artificial type 2 jaw-bone models. Specimens were tested under both vertical and oblique static loads at 190 N. Peak values of the principal bone strain were recorded and analyzed statistically by the Kruskal-Wallis test and multiple-comparisons Bonferroni test. Results: PTV and ISQ were higher for the NIOSM311 (internal-hex and Ti alloy) and FOSM311 (external-hex and pure Ti) implants, respectively, than for the NOSM311 (external-hex and Ti alloy) implant. Under vertical loading the peak value of peri-implant bone strains did not differ significantly among these three implant systems. However, the peak bone strains were at least 32 % lower for the NIOSM311 and FOSM311 implants than for the NOSM311 implant under lateral loading. Conclusions: The implant material and the implant-abutment connection design significantly influence the peri-implant bone strain of immediately loaded small-diameter implants, but barely affect their primary stability. Clinical Relevance: A commercially pure titanium implant with an internal connection has the potential to reduce the risk of implant failure of small-diameter implant related to biomechanical complications. [ABSTRACT FROM AUTHOR]

Tantalum (Ta) is a promising metal for biomedical implants or implant coating for orthopedic and dental applications because of its excellent corrosion resistance, fracture toughness, and biocompatibility. This study synthesizes biocompatible tantalum carbide (TaC) and TaC/amorphous carbon (a-C) coatings with different carbon contents by using a twin-gun magnetron sputtering system to improve their biological properties and explore potential surgical implant or device applications. The carbon content in the deposited coatings was regulated by controlling the magnetron power ratio of the pure graphite and Ta cathodes. The deposited TaC and TaC/a-C coatings exhibited better cell viability of human osteosarcoma cell line MG-63 than the uncoated Ti and Ta-coated samples. Inverted optical and confocal imaging was used to demonstrate the cell adhesion, distribution, and proliferation of each sample at different time points during the whole culture period. The results show that the TaC/a-C coating, which contained two metastable phases (TaC and a-C), was more biocompatible with MG-63 cells compared to the pure Ta coating. This suggests that the TaC/a-C coatings exhibit a better biocompatible performance for MG-63 cells, and they may improve implant osseointegration in clinics. [ABSTRACT FROM AUTHOR]

Abstract: This study used a twin-gun magnetron sputtering system to deposit ZrO2-silver (Ag) coatings on biograde pure-titanium implant materials, and the Ag content in the deposited coatings was controlled by the magnetron power. The films were then annealed using rapid thermal annealing at 350°C for 2min to induce the nucleation and growth of nanoparticles on the film surface. Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) were used for in vitro antibacterial analyses. The cytocompatibility, mRNA expression, and adhesive morphology of human gingival fibroblast (HGF) cells on the coatings were also determined. The obtained results suggest that ZrO2-Ag composite coatings containing less than 10.6at.% Ag show hydrophobicity, good viability and proliferation of HGF cells, and antibacterial effects on S. aureus and A. actinomycetemcomitans. Moreover, the antibacterial performance of ZrO2-Ag coatings is superior to that pure-titanium whilst maintaining biological compatibility. [Copyright &y& Elsevier]

Abstract: Composite metal nitride–metal (MeN–Me) physical vapor deposited (PVD) films (e.g. TaN–Cu, TiN–Cu, ZrN–Ag, etc.) are often considered for applications such as tribological and antibacterial coatings. In this study, ZrN, ZrO2–Ag and ZrNO–Ag coatings with different Ag contents were deposited by reactive magnetron sputtering. Monoclinic ZrO2 and fcc Ag composite structures were obtained when Zr and Ag were cosputtered to react with oxygen. ZrNO–Ag showed a porous structure containing monoclinic ZrO2, fcc Ag and Zr2ON2. Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) and Staphylococcus aureus (S. aureus), major pathogens frequently found in the implant-associated infections, were cultured on the coated samples. The antibacterial effects were determined using in vitro anti-bacterial analyses by a fluorescence staining method employing Syto9 and bacterial viability agar tests. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a MTT test assay. It showed that the nanostructure and Ag content of the ZrO2–Ag and ZrNO–Ag coatings were correlated with the biocidal property. The ZrN coating deposited by magnetron sputtering did not improve the bacterial reduction of A. actinomycetemcomitans and S. aureus. The ZrO2–Ag and ZrNO–Ag coated samples had lower bacterial retention, and the ZrNO–Ag coatings with silver content of 11.8at.% possessed the best antibacterial performance with excellent HGF cell compatibility as well. [Copyright &y& Elsevier]

Objectives: This study investigated the effects of gender on the three-dimensional (3D) bone mineral density (BMD) and micromorphology of the trabeculae of matured autogenous bone grafts after sinus floor augmentation, and compared them to those of adjacent native bone. Materials and methods: Ten bone biopsy samples were removed from the implant placement areas of patients who had received second-stage sinus floor augmentation, and analyzed by microcomputed tomography. BMD phantoms with two calcium hydroxyapatite densities (0.25 and 0.75 g/cm) were used to determine the BMD of the grafted and native bone samples. The 3D structural parameters of the trabeculae, including percentage of bone volume (bone volume/tissue volume, BV/TV), trabecular thickness (Tb.Th), trabecular number, trabecular separation, trabecular pattern factor (Tb.Pf), and structure model index, were analyzed between males and females and between grafted bone and native bone. Results: No significant gender-specific differences in BMD and 3D trabecular structure of either native or grafted bone were found ( P > 0.05). Compared to the adjacent native bone, the autogenous grafted bone exhibited lower BV/TV and Tb.Th as well as a higher Tb.Pf ( P < 0.05). Additionally, there was a weak positive correlation between the Tb.Th values of grafted and native bone ( R = 0.58). Conclusions: In the maxillary sinus, autogenous grafted bone exhibited lower BV/TV, Tb.Th, and trabecular connectivity than the adjacent native bone. No significant gender-specific differences were found for either the BMD or 3D trabecular structure of grafted bone. Clinical relevance: After bone remodeling, autogenous grafted bone revealed different 3D trabecular structure as compared to native bone. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to verify the antibacterial performance and cell proliferation activity of zirconium (Zr)–carbon (C)–nitride (N) coatings on commercially pure titanium (Ti) with different C contents. Materials and Methods: Reactive nitrogen gas (N2) with and without acetylene (C2H2) was activated by Zr plasma in a cathodic-arc evaporation system to deposit either a zirconium nitride (ZrN) or a Zr–C–N coating onto Ti plates. The bacterial activity of the coatings was evaluated against Staphylococcus aureus with the aid of SYTO9 nucleic acid staining and scanning electron microscopy (SEM). Cell compatibility, mRNA expression, and morphology related to human gingival fibroblasts (HGFs) on the coated samples were also determined by using the MTT assay, reverse transcriptase–polymerase chain reaction, and SEM. Results: The Zr–C–N coating with the highest C content (21.7 at%) exhibited the lowest bacterial preservation (P<0.001). Biological responses including proliferation, gene expression, and attachment of HGF cells to ZrN and Zr–C–N coatings were comparable to those of the uncoated Ti plate. Conclusions: High-C-content Zr–C–N coatings not only provide short-term antibacterial activity against S. aureus but are also biocompatible with HGF cells. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial adhesion and colonization are considered to play key roles in the pathogenesis of peri-implant disease, which is an inflammatory process leading the destruction of both soft and hard tissue around a Titanium (Ti) implant. The osseointegration of Ti implants is influenced by their composition and surface treatment. Zirconia (ZrO2) coatings have been shown to improve implant osseointegration in various biomedical fields, including orthopedic devices and dental implants. This study used a twin-gun magnetron sputtering system to deposit ZrO2–Sliver (Ag) and ZrO2–Copper (Cu) coatings on biograde pure-Ti implant materials. The effects of Ag and Cu on the antibacterial properties of the coated Ti samples were investigated using Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), which are found frequently in implant-associated infections. The in vitro antibacterial analyses employed a fluorescence staining method using SYTO9 and bacterial-viability tests on agar plates. Incorporating Ag and Cu into ZrO2 changed the structure of crystalline ZrO2, and the nanostructures of the resulting ZrO2–Ag and ZrO2–Cu coatings were found to be correlated with the antibacterial performance. The adherence of S. aureus and A. actinomycetemcomitans was less for ZrO2 samples with a small doping of Cu than for uncoated Ti. The ZrO2–Ag coating with an Ag content of 10.6at.%, which showed hydrophobicity, exhibited the lowest bacterial retention and viability of S. aureus and A. actinomycetemcomitans. The results suggest that ZrO2–Ag and ZrO2–Cu coatings improve the antibacterial performance relative to pure-Ti implant materials. [Copyright &y& Elsevier]

Objective The purpose of this study was to determine the relationships and differences in three-dimensional (3D) bone mineral density ( BMD) and microtrabecular structures between autogenous bone grafts and their adjacent native bone after a healing period following maxillary sinus augmentation. Materials and methods Nine rod-shaped human bone biopsy samples were taken from patients receiving two-stage sinus augmentation therapy in implantation areas and analyzed using microcomputed tomography (micro- CT). Before micro- CT scanning, two BMD phantoms were placed near to the bone biopsy samples for executing BMD calculations of the grafted and native bone samples. In addition, 3D structural parameters of the trabeculae were analyzed for both the grafted and native bone, including percentage of bone volume [bone volume ( BV)/tissue volume ( TV)], bone-specific surface [bone surface ( BS)/ BV], trabecular thickness ( Tb. Th), trabecular number ( Tb. N), trabecular separation ( Tb. Sp), trabecular pattern factor ( Tb. Pf), and structure model index ( SMI). Results No significant correlations with regard to BMD and trabecular-structure parameters were found between native bone and grafted bone; however, BS/ BV and Tb. Pf were higher and Tb. Th and Tb. Sp were 37.35% and 12.74% lower in grafted bone than in native bone. For grafted bone, there were significant correlations ( P < 0.05) between BMD and BV/ TV, and Tb. N. Conclusions When using autogenous bone as a graft material, BMD and micromorphological conditions of grafted bone were not influenced by the condition of the native bone in the maxilla. Differences were found in surface complexity, trabecular thickness, trabecular separation, and the connectivity of trabeculae between grafted and native bone. The BMD in grafted bone was affected by the quantity of the trabeculae. [ABSTRACT FROM AUTHOR]

The object of this study was to evaluate the relationship between changes in the alveolar bone density around the teeth and the direction of tooth movement by using cone-beam computed tomography (CBCT). CBCT was used to measure the bone densities around six maxilla anterior teeth before and after 7 months of orthodontic treatment in eight patients. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Three-dimensional computer models of the maxilla before and after orthodontic treatment were created to detect the direction of tooth movement. The percentage for all 144 samples [8 (patients) × 6 (teeth) × 3 (levels)] in which the side (palatal, distal, mesial, or buccal sides) of maximum bone density reduction (before and after orthodontic treatment) coincided with the direction of tooth movement was calculated; this was referred to as the 'coincidence percentage'. The bone density around the teeth reduced by 24.3 ± 9.5%. The average coincidence percentage for the eight patients was 59.0%. The coincidence percentages for the eight patients were 62.5%, 62.5%, and 52.1% at the cervical, intermediate, and apical levels, respectively. The obtained results demonstrate that the direction of tooth movement is associated with the side of maximum bone density reduction, and that CBCT is a useful approach for evaluating bone density changes around teeth induced by orthodontic treatment. [ABSTRACT FROM AUTHOR]

In orthodontic treatment, the efficiency of tooth movement is affected by the frictional force between the archwire and bracket slot. This study evaluated the static and kinetic frictional forces produced in different combinations of orthodontic archwires and brackets. Three types of archwires [stainless steel, nickel-titanium (NiTi) alloy, and beta-titanium (TMA) alloy] and two types of brackets (stainless steel and self-ligating) were tested. Both static and kinetic frictional forces of each archwire-bracket combination were measured 25 times using a custom-designed apparatus. The surface topography and hardness of the archwires were also evaluated. All data were statistically analyzed using two-way analysis of variance and Tukey's test. The experiments indicated that the static frictional force was significantly higher than the kinetic frictional force in all archwire-bracket combinations not involving TMA wire. TMA wire had the highest friction, followed by NiTi wire, and then stainless steel wire when using the stainless steel bracket. However, there was no difference between NiTi and stainless steel archwires when using the self-ligating bracket. For TMA wire, the friction was higher when using the stainless steel bracket than when using the self-ligating bracket. Scanning electron microscopy indicated that stainless steel wire exhibited the smoothest surface topography. The hardness decreased in the order of stainless steel wire > TMA wire > NiTi wire. This study demonstrates that the frictional forces of brackets are influenced by different combinations of bracket and archwire. The reported data will be useful to orthodontists. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of cortical bone thickness and trabecular bone elastic modulus on the strain in the bone surrounding an immediately loaded implant. We also examined the correlations between bone structure and the following indices of primary implant stability: insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ). The ITV, PTV, and ISQ were measured in 24 artificial jaw bone models representing cortical bone with four thicknesses (0, 1, 2, and 3 mm) and trabecular bone with four elastic moduli (137, 47.5, 23, and 12.4 MPa). Two loading conditions were applied (force of 130 N applied vertically and at 45° laterally), and the strains in the crestal region were measured by rosette strain gauges with a data acquisition system. When the cortical bone thickness and the elastic modulus of trabecular bone decreased, the bone strains increased by 10.3-52.1% and 39-73.1%, respectively, for vertical loading and by 35-62% and 42.4-56.2% for lateral loading. The cortical bone thickness has a stronger correlation ( R=0.95-0.71) with ITV, PTV, and ISQ than the elastic modulus of trabecular bone ( R=0.89-0.59). The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the elastic modulus of trabecular bone; however, these parameters are not totally linearly correlated with ITV, PTV, and ISQ. The placement of an immediately loaded implant in cases with thin cortical bone and/or weak trabecular bone can induce extreme bone strains and may increase the risk of implant failure. Huang H-L, Chang Y-Y, Lin D-J, Li Y-F, Chen K-T, Hsu J-T. Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study. Clin. Oral Impl. Res. , 2011; 691-698 doi: 10.1111/j.1600-0501.2010.01983.x [ABSTRACT FROM AUTHOR]

Abstract: Titanium-based materials have been used for dental implants due to their excellent biological compatibility, superior mechanical strength and high corrosion resistance. The osseointegration of titanium dental implants is related to their composition and surface treatment. A better anti-bacterial performance of the abutment seated in the prosthetic crown is beneficial for the osseointegration and for avoiding the infection after implantation surgery. In this study, TaN-Ag coatings with different Ag contents were deposited on a bio-grade pure Ti dental implant material. A twin-gun magnetron sputtering system was used for the deposition of TaN-Ag coatings. The Ag content in the deposited coatings was controlled by the magnetron power ratio of Ag/(Ta+Ag) targets. To verify the susceptibility of implant surface to bacterial adhesion, Staphylococcus aureus, one of the major pathogen frequently found in the implant-associated infections, was chosen for in vitro anti-bacterial analyses. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated. A composite structure of crystalline TaN and Ag nanoparticles was identified. The TaN-Ag coating with the highest Ag content of 21.4at.% possessed the lowest bacterial retention and viability of S. aureus. From the MTT assay test, the mean optical density values for the TaN and TaN-Ag coated samples after 72h of HGF adhesion were greater than the value obtained from the uncoated Ti. The results suggested that the TaN-Ag coatings improve antibacterial performance with compatible biological response. [ABSTRACT FROM AUTHOR]

Abstract: Experiment with rapid prototyping technique and validation finite element model was performed to evaluate the biomechanical behavior of an immediately loaded mandibular implant. Also, 18 finite element models of six implant designs and three surface roughnesses with anisotropic bone material properties were analyzed to compare the bone stresses and the sliding at the bone–implant interface under a vertical or lateral force of 130N. The results show that bone stress (strain) of an immediately loaded implant is heavily dependent on the implant design and surface roughness. Improving the initial interfacial interlocking using a threaded implant has a higher priority than using cylindrical or step designs with a rough surface for an immediately loaded implant. [Copyright &y& Elsevier]

Abstract: This study attempted to estimate the elastic modulus of cortical specimens directly from the computed tomography (CT) number (CT). Cubic specimens of fresh bovine femora were tested under compressive loading. The corresponding three-dimensional mesh models of these specimens were established with the aid of CT images. The elastic modulus of each element was determined using the following transfer formula: E=A×(CT)B. The A and B were determined by matching the simulation results with the experimental force–displacement curves. An optimization approach was used to match the entire specimen sets between simulations and experiments. The results indicated that the elastic modulus of cortical bone can be effectively estimated using a power relationship (E=1.26×10−3×(CT)1.93) directly from the CT number. This procedure eliminates the need to determine the bone density, and therefore reduces the computational time required to define mechanical properties in finite element methods. [Copyright &y& Elsevier]

Abstract: Objectives: This study investigated the surrounding bone stress and the implant–bone interfacial sliding of implant designs and implant sizes of immediately loaded implant with maxillary sinus augmentation by using three-dimensional (3D) non-linear finite element (FE) analysis. Methods: Twenty-four FE models including four implant designs (cylindrical, threaded, stepped and step-thread implants) and three implant dimensions (standard, long and wide threaded implants) with a bonded and three levels of frictional contact of implant–bone interfaces were analyzed. The maxillary model was constructed from computer tomography (CT) images of a human skull and all 3D implant models were created via the computer-aided design (CAD) software. Results: The use of threaded implants decreased the bone stress and sliding distance obviously about 30% as compared with non-threaded (cylindrical and stepped) implants. Increasing the implant''s length or diameter reduced the bone stress by 13–26%. Employing a immediately loaded implant with smooth machine surface (μ =0.3, μ represents frictional coefficient) increased the bone stress by 28–63% as compared with the osseointegrated (bonded interfaces) implants. Roughening the implant surface (μ >0.3) did not reduced the bone stress, however it did decrease the interfacial sliding between implant and bone. Conclusions: For an immediately loaded implant placed with sinus augmentation, using threaded implant could decrease both the bone stress and implant–bone sliding distance which may improve the implant initial stability and long-term survival. Rough surface of implants shows no benefit to reduce the bone stress but they could lower the interfacial sliding. On the contrary, employing long or wide implants decrease the bone stress but they cannot diminish the interfacial sliding. [Copyright &y& Elsevier]

Three-dimensional finite element (FE) models of splinted prosthetic crowns were studied and stress analyses were evaluated with different types of implant support, including standard, wide or two implant(s) for partial, posterior edentulous restorations. The FE models were constructed based on a cadaver mandible containing the 2nd premolar and the 1st molar. The crowns of these two teeth were modeled as connected and disconnected to mimic the splinted and non-splinted designs, respectively. One standard implant was placed at the premolar region, while three types of implant support, one at a time (the standard implant, wide implant and two implants), were used to support the molar crown. A 100 N oblique load was applied to the buccal cusp on each crown. The FE simulation was validated experimentally via strain gauge measurement. The experimental data were well correlated with the FE predictions ( r2=0.97). When compared with the standard implant used in the molar area, the wide implant and two implants reduced the peak stress in crestal bone by 29–37% for both splinted and non-splinted cases. Inserting the standard implant into both the premolar and molar area, the bone stresses were identical for splinted and non-splinted designs. However, splinting the adjacent crowns has shown to decrease the bone stresses at the premolar region by 25%, while the wide implant or two implants were placed at the molar region. The biomechanical advantages of using the wide implant or two implants are almost identical. The benefit of load sharing by the splinted crowns is notable only when the implants on the premolar and molar regions have different supporting ability. [ABSTRACT FROM AUTHOR]

Background: Dental cone beam computed tomography (CBCT) is commonly used to evaluate cancellous bone density before dental implant surgery. However, to our knowledge, no measurement approach has been standardized yet. This study aimed to evaluate the relationship between three different regions of interest (ROI) methods on cancellous bone density at the dental implant site using dental CBCT images. Methods: Patients' dental CBCT images (n = 300) obtained before dental implant surgery were processed using Mimics (Materialise, Leuven, Belgium). At the potential implant sites, the rectangle, cylinder, and surrounding cylinder ROI methods were used to measure bone density. Repeated measures one-way analysis of variance was performed to compare the three ROI methods in terms of measurement results. Pearson correlation analysis was performed to identify the likely pair-wise correlations between the three ROI methods. Results: The density value obtained using the surrounding cylinder approach (grayscale value [GV],523.56 ± 228.03) was significantly higher than the values obtained using the rectangle (GV, 497.04 ± 236.69) and cylinder (GV,493 ± 231.19) ROI methods in terms of results. Furthermore, significant correlations were noted between the ROI methods (r > 0.965; p < 0.001). Conclusions: The density measured using the surrounding cylinder method was the highest. The choice of method may not influence the trends of measurement results. Trial registration: This study was approved by the Institutional Review Board of China Medical University Hospital, No. CMUH111-REC3-205. Informed consent was waived by the Institutional Review Board of China Medical University Hospital, CMUH111-REC3-205, owing to the retrospective nature of the study. [ABSTRACT FROM AUTHOR]

In this study, amorphous tantalum oxide coatings were deposited onto the Ti substrate with and without plasma electrolytic oxidation (PEO)-pretreatment by using a high-powered impulse magnetron sputtering system. The antibacterial tests were conducted using Syto9 fluorescent dyes to study the antibacterial performance of Gram-positive (Staphylococcus aureus) and Gram-negative (Actinobacillus actinomycetemcomitans) bacteria. In vitro studies, the cell cytotoxicity and cell viability were evaluated with soft-tissue derived human skin fibroblasts and hard-tissue derived human osteosarcoma cells. The results of the antibacterial experiments revealed that both the Ta 2 O 5 and PEO-pretreated Ta 2 O 5 samples had superior antibacterial properties compared to the uncoated Ti samples. Cell viability analyses showed that the Ta 2 O 5 films with and without PEO pretreatment exhibited better cell growth compared to the Ti specimens in human skin fibroblasts and human osteosarcoma cells. The cell viability of PEO-pretreated Ta 2 O 5 films even two-fold higher than the Ti specimens in human osteosarcoma cells. In addition, no cytotoxicity was detected in both the Ta 2 O 5 and PEO-pretreated Ta 2 O 5 films. It concluded that porous Ta 2 O 5 film pretreated with PEO procedure possessed both great biocompatibility and antibacterial abilities. It might have highly potential to be a candidate for the surface materials of dental or orthopedic implants. • Amorphous Ta 2 O 5 are deposited by high-powered impulse magnetron sputtering. • The plasma electrolytic oxidation-pretreated Ta 2 O 5 has the highest hydrophilicity. • The Ta 2 O 5 coatings showed good antibacterial properties. • The cell viability of human skin fibroblasts is the highest for the Ta 2 O 5 coatings. • The MG-63 cell viability is the highest for the porous PEO-pretreated Ta 2 O 5 coatings. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the effects of the contact percentage (BMC%) of three-dimensional (3D) bone-to-miniscrew specimens in relation to host bone quality on initial miniscrew stability. Furthermore, their correlations were evaluated. Methods: Orthodontic miniscrews (1.6 mm in diameter and 11 mm in length) were inserted into four types of artificial bones to measure the maximum insertion torque value (ITV). The miniscrew and artificial foam bone specimens were also scanned using microcomputed tomography, and the obtained images were imported into Mimics software to reconstruct the 3D models and calculate the BMC%. The Kruskal–Wallis test, Wilcoxon rank-sum test with Bonferroni adjustment, and Spearman correlations were applied for statistical and correlation analyses. Results and Conclusions: Inserting the orthodontic miniscrew into artificial foam bone exhibiting higher bone quality resulted in higher maximum ITV and BMC%. The initial implant stability, quantified using ITV, was strongly positively (r = 0. 9 7) and correlated with BMC%, as measured from microcomputed tomography images. [ABSTRACT FROM AUTHOR]

Background: Zirconia materials are known for their optimal aesthetics, but they are brittle, and concerns remain about whether their mechanical properties are sufficient for withstanding the forces exerted in the oral cavity. Therefore, this study compared the maximum deformation and failure forces of titanium implants between titanium-alloy and zirconia abutments under oblique compressive forces in the presence of two levels of marginal bone loss.Methods: Twenty implants were divided into Groups A and B, with simulated bone losses of 3.0 and 1.5 mm, respectively. Groups A and B were also each divided into two subgroups with five implants each: (1) titanium implants connected to titanium-alloy abutments and (2) titanium implants connected to zirconia abutments. The maximum deformation and failure forces of each sample was determined using a universal testing machine. The data were analyzed using the nonparametric Mann-Whitney test.Results: The mean maximum deformation and failure forces obtained the subgroups were as follows: A1 (simulated bone loss of 3.0 mm, titanium-alloy abutment) = 540.6 N and 656.9 N, respectively; A2 (simulated bone loss of 3.0 mm, zirconia abutment) = 531.8 N and 852.7 N; B1 (simulated bone loss of 1.5 mm, titanium-alloy abutment) = 1070.9 N and 1260.2 N; and B2 (simulated bone loss of 1.5 mm, zirconia abutment) = 907.3 N and 1182.8 N. The maximum deformation force differed significantly between Groups B1 and B2 but not between Groups A1 and A2. The failure force did not differ between Groups A1 and A2 or between Groups B1 and B2. The maximum deformation and failure forces differed significantly between Groups A1 and B1 and between Groups A2 and B2.Conclusions: Based on this experimental study, the maximum deformation and failure forces are lower for implants with a marginal bone loss of 3.0 mm than of 1.5 mm. Zirconia abutments can withstand physiological occlusal forces applied in the anterior region. [ABSTRACT FROM AUTHOR]

Development of oxide films on metallic implants with a desirable combination of mechanical properties and biocompatibility can greatly improve its functionality and application to the medical implant field. The present work is aimed to fabricate titanium (Ti) or zirconium (Zr) oxide films with porous structures onto Ti substrates by micro-arc oxidation (MAO) procedure. Before the MAO treatment, a series of Ti Zr alloy films were deposited on polished pure Ti substrates using a cathodic arc deposition system with different deposition cathode current ratios of Zr/Ti. The post-MAO-treated surface layers were characterized for its composition, crystalline structure, bonding states, surface morphology, and wettability. The results showed that porous crystalline titanium and zirconium oxides were formed using the MAO treatment for the Ti Zr films. To evaluate the bioactivity, cell viability and gene expression of human osteosarcoma cell line (MG-63) and human skin fibroblast cell line (SKF) cultured on different Ti Zr oxide films were determined. The results of MTT tests showed that the higher cell viability of MG-63 and SKF cells was found in MAO-treated Ti Zr films with higher Zr content. Gene expression data by RT-PCR and agarose gel electrophoresis showed that MG-63 cells and SKF cells exhibited notable osteogenic gene expression, such as Runx2, ALP, Dlx-5, OCN, BMP-2 and BMPR1A. The cell adhesion-related genes, such as fibronectin, collagen types I and III, and laminin were also remarkably expressed in the gel imaging. It suggested that the MAO-treated Ti Zr films were suitable for bone tissue- or soft tissue-derived cell growth and differentiation. The design and fabrication of Ti Zr oxide films with specific composition and porous surface layer with MAO treatment may provide a better material environment for cell bonding, living, and differentiation in dental and orthopedic implants. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of bone–miniscrew contact percentage (BMC%) and bone quality and quantity on orthodontic miniscrew stability and the maximum insertion torque value (ITV). Orthodontic miniscrews of five different dimensions and several bovine iliac bone specimens were used in the evaluation. Miniscrews of each dimension group were inserted into 20 positions in bovine iliac bone specimens. The experiment was divided into three parts: (1) Bone quality and quantity were evaluated using cone-beam computed tomography (CBCT) and microcomputed tomography. (2) The 3D BMC% was calculated. (3) The ITVs during miniscrew insertion were recorded to evaluate the stability of the orthodontic miniscrews. The results indicated that longer and thicker miniscrews enabled higher ITVs. CBCT was used to accurately measure cortical bone thickness (r = 0.939, P < 0.05) and to predict the bone volume fraction of cancellous bone (r = 0.752, P < 0.05). BMC% was significantly influenced by miniscrew length. The contribution of cortical bone thickness to the ITV is greater than that of cancellous bone structure, and the contribution of cortical bone thickness to BMC% is greater than that of cancellous bone structure. Finally, the higher is BMC%, the greater is the ITV. This study concludes that use of CBCT may predict the mechanical stability of orthodontic miniscrews. [ABSTRACT FROM AUTHOR]

Abstract: Tantalum is considered a highly biocompatible metal with high corrosion resistance. Metal-doped amorphous carbon films are gaining interest as an effective surface modifier for medical devices. In this study, tantalum (Ta), TaC/amorphous carbon (a-C), and Ta-containing amorphous hydrogenated carbon films (Ta-C:H) were synthesized using a twin-gun magnetron sputtering system to improve biological properties and explore potential applications for surgical implants or devices. Reactive C2H2, activated by the tantalum plasma in the magnetron sputtering process, was used to deposit the Ta-C:H coatings. The deposited TaC/a-C coatings, in which TaC was embedded in the amorphous carbon matrix as a nanocomposite film, exhibited favorable cell viability of the human osteosarcoma cell line (MG-63), similar to uncoated titanium. Among the examined materials, Ta-C:H coatings exhibited the highest biocompatibility for WS1 human fetal skin fibroblast cells derived from soft tissues and demonstrated the highest biological performance. [Copyright &y& Elsevier]

Abstract: Titanium (Ti)-based materials have been used for dental and orthopedic implants because of their excellent biological compatibility, superior mechanical strength, and high corrosion resistance. The hypothesis of this present study was to manufacture the Zn-doped TiO2 layer possessing the biocompatibility and antibacterial ability on the surface of Ti specimens. TiO2, ZnO, and Ti(Zn)O2 coatings were deposited on polished pure Ti substrates using a cathodic arc deposition system. Murine osteoblasts (MC3T3-E1) and human Staphylococcus aureus (S. aureus) were cultured onto the surface with different deposited coatings, respectively. The biocompatibility was examined by cell viability and osteogenic gene expression. The antibacterial ability was determined by SYTO9 nucleic acid staining. A porous Zn-doped TiO2 coating was successfully produced. The ZnO exhibited a fibrous structure with nanorods showing a hydrophobic feature (contact angle approximately 89°). These material properties affected the following biological performance. The antibacterial testing found no apparent difference between the uncoated Ti plate and the TiO2 coating. However, significantly lower numbers of S. aureus were observed on ZnO and Ti(Zn)O2 coatings compared to that on the uncoated Ti. The biocompatible testing exhibited that TiO2 and Ti(Zn)O2 coatings enhanced greater cell viability and proliferation than the uncoated Ti plate and ZnO coating. The osteogenic gene expression of Dlx-5 and osterix also improved for the TiO2 and Ti(Zn)O2 coatings. However, a significant inhibition of cell viability was found for the ZnO coating. These findings suggested that the composite Ti(Zn)O2 coating with a lower content of Zn (7.6±1.3at.%) not only improved antibacterial activity, but also maintained the biocompatibility to bone cells. [Copyright &y& Elsevier]

Objectives: The purpose of this study was to determine the correlation between the peak insertion torque value (ITV) of a dental implant and the bone-implant contact percentage (BIC%). Material and methods: Dental implants were inserted into specimens comprising a 2-mm-thick artificial cortical shell representing cortical bone and artificial foam bone representing cancellous bone with four densities (groups 1 to 4-0.32, 0.20, 0.16, and 0.12 g/cm). Each specimen with an inserted implant was subjected to micro-computed tomography (micro-CT) scanning, from which the 3D BIC% values were calculated. Pearson's correlation coefficients ( r) between the ITV and BIC% were calculated. Results: The ITVs in groups 1 to 4 were 56.2 ± 4.6 (mean±standard deviation), 45.6 ± 0.9, 43.3 ± 4.3, and 38.5 ± 3.4 N cm, respectively, and the corresponding BIC% values were 41.5 ± 0.5%, 39.0 ± 1.0%, 30.8 ± 1.1%, and 26.2 ± 1.6%. Pearson's correlation coefficient between the ITV and BIC% was r = 0.797 ( P < 0.0001). Conclusion: The initial implant stability, quantified as the ITV, was strongly positively correlated with the 3D BIC% obtained from micro-CT images. Clinical relevance: The ITV of a dental implant can be used to predict the initial BIC%; this information may provide the clinician with important information on the optimal loading time. [ABSTRACT FROM AUTHOR]

Abstract: Titanium (Ti)-based materials have been used for dental/orthopedic implants due to their excellent biological compatibility, superior mechanical strength and high corrosion resistance. The osseointegration of Ti implants is related to their composition and surface treatment. Better biocompatibility and anti-bacterial performances of Ti implant are beneficial for the osseointegration and for avoiding the infection after implantation surgery. In this study, nanocomposite ZrCN/amorphous carbon (a-C) coatings with different carbon contents were deposited on a bio-grade pure Ti implant material. A cathodic-arc evaporation system with plasma enhanced duct equipment was used for the deposition of ZrCN/a-C coatings. Reactive gas (N2) and C2H2 activated by the zirconium plasma in the evaporation process were used to deposit the ZrCN/a-C coatings. To verify the susceptibility of implant surface to bacterial adhesion, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), one of the major pathogen frequently found in the dental implant-associated infections, was chosen for in vitro anti-bacterial analyses. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a cell proliferation assay. The results suggested that the ZrCN/a-C coatings with carbon content higher than 12.7at.% can improve antibacterial performance with excellent HGF cell compatibility as well. [Copyright &y& Elsevier]

The objective of this study was to evaluate bone density changes around the teeth during orthodontic treatment by using cone beam computed tomography (CBCT). CBCT was used to measure the bone densities around six teeth (both maxilla central incisors, lateral incisors, and canines) before and after 7 months of orthodontic treatment in eight patients. In addition, each root was divided into three portions (cervical, intermediate, and apical) to determine whether the bone density change varied with tooth level. The mean reduction in bone density around the measured teeth was 24% after orthodontic treatment. The bone density reduction around teeth was largest for the upper-right and upper-left central incisor (29% and 26%, respectively) and ranged from 20% to 23% for the other four teeth. The mean bone density reduction did not differ significantly between the cervical, portion, and apical portions of the teeth (26%, 22%, and 24%, respectively). CBCT is useful for evaluating bone density changes around teeth during orthodontic treatment. The bone density around the teeth reduced significantly after the application of orthodontic forces for 7 months. [ABSTRACT FROM AUTHOR]

Abstract: One of the major causes of loosening of cementless acetabular cup implants is insufficient initial stability. This study used three-dimensional finite element models of the pelvis and acetabular components to investigate the effects of the number of screws, bone quality, and friction coefficient of the acetabular cup on the initial stability under normal walking. A commercially available hemispherical acetabular cup with five screw holes was used as the default model. The stiffness of the pelvis and the friction coefficient of the cup were systematically varied, within a realistic range, to assess the initial stability of the acetabular cup. The simulations showed that the inserted screws provide only a localized reduction in the relative micromotion between the cup and pelvis therefore inserting several screw closed together might not be useful. Changes in the pelvic stiffness have a non-linear effect on the initial stability of acetabular cup and the subchondral bone provides good support for fixation of the cementless cup. The friction coefficient of the acetabular cup plays a limited role, comparing with the factor of bone quality, in resisting relative micromotion in the cup–pelvis interface. [Copyright &y& Elsevier]

Background: Metacarpal shaft fracture is a common fracture in hand trauma injuries. Surgical intervention is indicated when fractures are unstable or involve considerable displacement. Current fixation options include Kirschner wire, bone plates, and intramedullary headless screws. Common complications include joint stiffness, tendon irritation, implant loosening, and cartilage damage.Objective: We propose a modified fixation approach using headless compression screws to treat transverse or short-oblique metacarpal shaft fracture.Materials and Methods: We used a saw blade to model transverse metacarpal neck fractures in 28 fresh porcine metacarpals, which were then treated with the following four fixation methods: (1) locked plate with five locked bicortical screws (LP group), (2) regular plate with five bicortical screws (RP group), (3) two Kirschner wires (K group), and (4) a headless compression screw (HC group). In the HC group, we proposed a novel fixation model in which the screw trajectory was oblique to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; thus, the screw did not damage the articular cartilage. The specimens were tested using a modified three-point bending test on a material testing system. The maximum fracture forces and stiffness values of the four fixation types were determined by observing the force-displacement curves. Finally, the Kruskal-Wallis test was adopted to process the data, and the exact Wilcoxon rank sum test with Bonferroni adjustment was performed to conduct paired comparisons among the groups.Results: The maximum fracture forces (median ± interquartile range [IQR]) of the LP, RP, HC, and K groups were 173.0 ± 81.0, 156.0 ± 117.9, 60.4 ± 21.0, and 51.8 ± 60.7 N, respectively. In addition, the stiffness values (median ± IQR) of the LP, HC, RP, and K groups were 29.6 ± 3.0, 23.1 ± 5.2, 22.6 ± 2.8, and 14.7 ± 5.6 N/mm, respectively.Conclusion: Headless compression screw fixation provides fixation strength similar to locked and regular plates for the fixation of metacarpal shaft fractures. The headless screw was inserted obliquely to the long axis of the metacarpal bone. The entry point of the screw was in the dorsum of the metacarpal neck, and the exit point was in the volar cortex of the supracondylar region; therefore the articular cartilage iatrogenic injury can be avoidable. This modified fixation method may prevent tendon irritation and joint cartilage violation caused by plating and intramedullary headless screw fixation. [ABSTRACT FROM AUTHOR]

Assessing bone quality and quantity at the location of dental implants before dental implantation is crucial. In recent years, dental cone-beam computed tomography (dental CBCT) has often been used to assess bone quality and quantity prior to dental implant. However, the effect of scanning resolution on the prediction of trabecular bone microarchitectural parameters (TBMPs) remains unclear. The objective of this study was to examine how dental CBCT with various scanning resolution differs with regard to predicting TBMPs. This study used micro-computed tomography (micro-CT) with 18 μm resolution and dental CBCT with 100 μm and 150 μm resolutions on 28 fresh bovine vertebrae cancellous bone specimens. Subsequently, all images were input into the ImageJ software to measure four TBMPs: bone volume total volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp). One-way analysis of variance and Tukey's test were subsequently used to assess the differences between three scanning modes for the four TBMPs. In addition, correlations between measurement results obtained from micro-CT and dental CBCT with two resolutions were measured. The experimental results indicated that significant differences in four TBMPs were observed between micro-CT and dental CBCT (p < 0.05). The correlation coefficients between BV/TV, Tb.N, and Tb.Sp obtained from micro-CT and from dental CBCT with 100 μm resolution (0.840, 0.739, and 0.820, respectively) were greater than the correlation coefficients between BV/TV, Tb.N, and Tb.Sp obtained from micro-CT and from dental CBCT with 150 μm resolution (0.758, 0.367, and 0.724, respectively). The experimental results revealed that the TBMPs measured with dental CBCT with two resolutions differed from ideal values, but a higher resolution could provide more accurate prediction results, particularly for BV/TV, Tb.N, and Tb.Sp. [ABSTRACT FROM AUTHOR]

Background: Clinicians needed to be aware of the thinness of the palatal bone plate when identifying severe protrusion of maxillary incisors, as this could result in perforation of the palatal bone plate during surgical procedures associated with immediate maxillary implant placement. Purpose: This study evaluated the thickness of the palatal bone plate, the buccolingual angulation of maxillary incisors, and the correlation between these two parameters in relation to immediate implant placement. Materials and Methods: Cone‐beam computed tomography images of 37 Asian patients (20‐60 years old) with no evidence of dental treatment in the maxillary incisor area were collected and classified into groups based on sex and incisor locations. Sagittal slices were used to measure the palatal bone plate thickness at the cervical, middle, and apical levels, and the buccolingual angulation of each tooth was also measured. The intraclass correlation, Shapiro‐Wilk test, descriptive analysis, Student's t‐test, and Pearson correlation were used for statistical and correlation analyses, with P < .05 applied as the criterion for statistical significance. Results: At the apical level of all inspected teeth and the middle level of lateral incisors, the palatal bone was significantly thicker in males than in females. The inclination of the maxillary lateral incisor showed a moderate negative linear correlation with the palatal bone thickness at the apical level (R = −0.517 and R = −0.579 for males and females, respectively). Conclusions: In an Asian population, an increased buccolingual angulation of the maxillary lateral incisors was correlated with a thinner palatal bone plate at the apical level. [ABSTRACT FROM AUTHOR]

Titanium dioxide and vanadium oxides have been applied extensively in industrial and medical fields. The objective of this study was to develop various composite structures of titanium and vanadium oxide (Ti-V-O) coatings on pure titanium through high-temperature annealing and laser texturing oxidation, separately; additionally, surface morphologies, tribological and hydrophilic properties, and antibacterial and biocompatibility abilities of these Ti-V-O coatings were evaluated. TiV alloy thin films were deposited on pure titanium and then annealed to form Ti-V-O coatings through thermal oxidation and laser texturing oxidation. Ball-on-disc wear tests and contact angle tests were conducted to evaluate the tribological properties and wettability of the coatings, respectively. The antibacterial activity of the coatings was estimated by SYTO9 nucleic acid staining with Staphylococcus aureus (Gram-positive bacteria). The cell cytotoxicity of the coatings was analyzed following the ISO 10995-5:2009 standard with human skin fibroblast cells. The Ti-V-O coatings, subjected to annealing at 700 °C, demonstrated higher hardness (Hv 1171) and a lower friction coefficient (0.6). The highest hardness (Hv 2711) and the lowest friction coefficient (0.52) were obtained for the Ti-V-O after laser surface texturing oxidation at 100 kHz. The oxide coating obtained from 100 kHz laser texturing oxidation exhibited the lotus effect because of its systematic textured microstructures, and displayed superhydrophobic surface properties. Compared with the unannealed TiV coating, both the samples with high-temperature annealing and laser surface texturing oxidation had excellent antibacterial properties to Staphylococcus aureus. However, the Ti-V-O thin films exhibited notable cell cytotoxicity. Although the cell viability on Ti-V-O coatings were not ideal, this study confirmed improvement in surface hardness, tribology, and antibacterial performance in Ti-V-O coatings, which may have potential for use in biomedical tools, devices, and equipment. [ABSTRACT FROM AUTHOR]

This study used available or purchased equipment and an image reconstruction system developed by the college of dentistry to establish a basic self-assembled micro-computed tomography (micro-CT) system. Such a system would be suitable for teaching dental radiology to dental students. Specifically, it could help students to understand the principles governing dental cone-beam computed tomography (CBCT) and provide graduate students with a system for scanning small samples (e.g., individual teeth) during the early stages of research. The self-assembled micro-CT system was constructed using a portable dental X-ray tube, an intraoral digital X-ray detector, a high-precision rotation stage, related bracket accessories, and a notebook computer. Reconstructed images and three-dimensional models of the maxillary right third molar were produced using the self-assembled micro-CT system and an advanced commercially available micro-CT system (Skyscan 2211). Subsequently, the reconstructed images and 3D models produced using the two systems were compared by two senior dentists to determine whether considerable visual differences could be observed. Finally, the signal-to-noise ratio (SNR) was used for quantitative analysis and to compare the systems. Although the self-assembled micro-CT system produced image boundaries that were not as sharp as those of Skyscan 2211, the images were nonetheless remarkably similar. In addition, the two micro-CT systems produced 3D models that were almost identical in appearance and root canal shape. Quantitative analysis revealed that Skyscan 2211 had produced a SNR that was superior to that of the self-assembled micro-CT system, with the difference ranging from 36.77% to 136.22%; enamel, which has a higher density, exhibited lower SNR differences, whereas dentin, which has a lower density, exhibited higher SNR differences. The self-assembled micro-CT system with a resolution of 36 μm was created using a portable dental X-ray tube and an intraoral digital X-ray detector. Although the scanning time was relatively long (~30 min to scan images of a tooth), the images were adequate in the preliminary stage of experiments. More importantly, students were afforded the opportunity to observe the process of assembling and disassembling each component of a micro-CT scanner and thereby achieve a more comprehensive understanding of the principles governing micro-CT and dental CBCT. [ABSTRACT FROM AUTHOR]

Background: Intermittent parathyroid hormone (PTH) can be used to treat osteoporosis of the spine and hip. However, whether it can be used to treat osteoporosis of the mandible is unclear. The purpose of this study was to explore the influence of applying intermittent PTH to ovariectomized rats on the trabecular bone microarchitecture of the mandible and femoral head.Methods: Eighteen female rats were divided into three groups: the healthy group, ovariectomized (OVX) group, and OVX + PTH group. The OVX group and OVX + PTH group had an OVX at 8 weeks of age. The OVX + PTH group received intermittent PTH therapy for 12 weeks. The mandibles and femurs of all rats were removed at 20 weeks and were then scanned using microcomputed tomography (micro-CT).Results: From the micro-CT analysis, the trabecular bone microarchitecture of the mandible and femoral head are offered as follows: (1) The bone volume fraction and trabecular thickness in the OVX group were lower than those in the healthy group. (2) The bone volume fraction and trabecular thickness in the OVX + PTH group approximated those in the healthy group.Conclusion: The conclusions of this study regarding the trabecular bone microarchitecture of the mandible and femoral head are offered as follows: (1) The BV/TV and TbTh in the OVX group were lower than those in the healthy group. (2) The BV/TV and TbTh in the OVX + PTH group approximated those in the healthy group, therefore, intermittent PTH displayed high efficacy for treating femoral or mandibular deterioration of bone microstructure resulting from loss of ovarian function. Osteoporosis of the femur or mandible in the rats was ameliorated by intermittent PTH therapy. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to evaluate the relationship between the trabecular bone microarchitecture and cortical bone morphology by using micro-computed tomography (micro-CT) and dental cone-beam computed tomography (dental CT). Materials and Methods: Sixteen femurs and eight fifth lumbar vertebrae were collected from eight male Sprague Dawley rats. Four trabecular bone microarchitecture parameters related to the fifth lumbar vertebral body (percent bone volume [BV/TV], trabecular thickness [TbTh], trabecular separation [TbSp], and trabecular number [TbN]) were calculated using micro-CT. In addition, the volumetric cancellous bone grayscale value (vCanGrayscale) of the fifth lumbar vertebral body was measured using dental CT. Furthermore, four cortical bone morphology parameters of the femoral diaphysis (total cross-sectional area [TtAr], cortical area [CtAr], cortical bone area fraction [CtAr/TtAr], and cortical thickness [CtTh]) were calculated using both micro-CT and dental CT. Pearson analysis was conducted to calculate the correlation coefficients (r) of the micro-CT and dental CT measurements. Paired-sample t tests were used to compare the differences between the measurements of the four cortical bone morphology parameters obtained using micro-CT and dental CT. Results: High correlations between the vCanGrayscale measured using dental CT and the trabecular bone microarchitecture parameters (BV/TV [r = 0.84] and TbTh [r = 0.84]) measured using micro-CT were observed. The absolute value of the four cortical bone morphology parameters may be different between the dental CT and micro-CT approaches. However, high correlations (r ranged from 0.71 to 0.90) among these four cortical bone morphology parameters measured using the two approaches were obtained. Conclusion: We observed high correlations between the vCanGrayscale measured using dental CT and the trabecular bone microarchitecture parameters (BV/TV and TbTh) measured using micro-CT, in addition to high correlations between the cortical bone morphology measured using micro-CT and dental CT. Further experiments are necessary to validate the use of dental CT on human bone. [ABSTRACT FROM AUTHOR]

Background: the clinical application of orthopedic or dental implants improves the quality of the lives of patients. However, the long-term use of implants may lead to implant loosening and related complications. The purpose of this study is to deposit titanium (Ti)-niobium (Nb)-zirconium (Zr)-tantalum (Ta) alloys on the surface of Ti-6Al-4V to increase structural strength and biocompatibility for the possible future application of implants. Materials and methods: Ti, Nb, Zr, and Ta served as the materials for the surface modification of the titanium alloy. TiNbZr and TiNbZrTa coatings were produced using cathodic arc evaporation, and a small amount of nitrogen was added to produce TiNbZrTa(N) film. Annealing and oxidation were then conducted to produce TiNbZrTa-O and TiNbZrTa(N)-O coatings. In this study, biological tests and finite element analyses of those five alloy films, as well as uncoated Ti-6Al-4V, were performed. Human osteosarcoma cells (MG-63) and mouse fibroblast cells (L-929) were used to analyze cytotoxicity, cell viability, and cell morphology, and the bone differentiation of MG-63 was evaluated in an alkaline phosphatase experiment. Furthermore, for measuring the gene expression level of L-929, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was conducted. The three-dimensional (3D) computational models of the coated and uncoated sample films were constructed using images of transmission electron microscopy and computer-aided design software and, then, the stress distributions of all models were evaluated by finite element analysis. Result: the cytotoxicity test revealed that the surface treatment had no significant cytotoxic effects on MG-63 and L-929 cells. According to the results of the cell viability of L-929, more cell activity was observed in the surface-treated experimental group than in the control group; for MG-63, the cell viability of the coated samples was similar to that of the uncoated samples. In the cell morphology analysis, both MG-63 and L-929 exhibited attached filopodia and lamellipodia, verifying that the cells were well attached. The alkaline phosphatase experiment demonstrated that the surface treatment did not affect the characteristics of early osteogenic differentiation, whereas RT-qPCR analysis showed that surface treatment can promote better performance of L-929 cells in collagen, type I, α1, and fibronectin 1. Finally, the results of the finite element analysis revealed that the coated TiNb interlayer can effectively reduce the stress concentration inside the layered coatings. Conclusions: TiNbZrTa series films deposited using cathodic arc evaporation had excellent biocompatibility with titanium alloys, particularly in regard to soft tissue cells, which exhibited an active performance. The finite element analysis verified that the TiNb interlayer can reduce the stress concentration inside TiNbZrTa series films, increasing their suitability for application in biomedical implants in the future. [ABSTRACT FROM AUTHOR]

Objective: This study compared the adequacy of dental cone beam computed tomography (CBCT) and micro computed tomography (micro-CT) in evaluating the structural parameters of trabecular bones.Methods: The cellular synthetic bones in 4 density groups (Groups 1-4: 0.12, 0.16, 0.20, and 0.32 g/cm3) were used in this study. Each group comprised 8 experimental specimens that were approximately 1 cm3. Dental CBCT and micro-CT scans were conducted on each specimen to obtain independent measurements of the following 4 trabecular bone structural parameters: bone volume fraction (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th.), and trabecular separation (Tb.Sp.). Wilcoxon signed ranks tests were used to compare the measurement variations between the dental CBCT and micro-CT scans. A Spearman analysis was conducted to calculate the correlation coefficients (r) of the dental CBCT and micro-CT measurements.Results and Conclusion: Of the 4 groups, the BV/TV and Tb.Th. measured using dental CBCT were larger compared with those measured using micro-CT. By contrast, the BS/BV measured using dental CBCT was significantly less compared with those measured using micro-CT. Furthermore, in the low-density groups (Groups 1 and 2), the Tb.Sp. measured using dental CBCT was smaller compared with those measured using micro-CT. However, the Tb.Sp. measured using dental CBCT was slightly larger in the high-density groups (Groups 3 and 4) than it was in the low density groups. The correlation coefficients between the BV/TV, BS/BV, Tb.Th., and Tb.Sp. values measured using dental CBCT and micro-CT were 0.9296 (p < .001), 0.8061 (p < .001), 0.9390 (p < .001), and 0.9583 (p < .001), respectively. Although the dental CBCT and micro-CT approaches exhibited high correlations, the absolute values of BV/TV, BS/BV, Tb.Th., Tb.Sp. differed significantly between these measurements. Additional studies must be conducted to evaluate using dental CBCT in clinical practice. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose: This study investigated how the primary stability of a dental implant as measured by the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) is affected by varying thicknesses of cortical bone and strengths of trabecular bone using synthetic bone models. Materials and Methods: Four synthetic cortical shells (with thicknesses of 0, 1, 2, and 3 mm) were attached to four cellular rigid polyurethane foams (with elastic moduli of 137, 47.5, 23, and 12.4 MPa) and one open-cell rigid polyurethane foam which mimic the osteoporotic bone (with an elastic modulus 6.5 MPa), to represent the jawbones with various cortical bone thicknesses and strengths of trabecular bone. A total of 60 bone specimens accompanied with implants was examined by a torque meter, Osstell resonance frequency analyzer, and Periotest electronic device. All data were statistically analyzed by two-way analysis of variance. In addition, second-order nonlinear regression was utilized to assess the correlations of the primary implant stability with the four cortex thicknesses and five strengths of trabecular bone. Results: ITV, ISQ, and PTV differed significantly ( p < .05) and were strongly correlated with the thickness of cortical bone ( R2 > 0.9) and the elastic modulus of trabecular bone ( R2 = 0.74-0.99). Conclusions: The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the strength of trabecular bone; however, these factors are mostly nonlinearly correlated with ITV, PTV, and ISQ. Using ITV and PTV seems more suitable for identifying the primary implant stability in osteoporotic bone with a thin cortex. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of the cyclic stretching speed on the force degradation of orthodontic elastics. Forty-five natural rubber bands (3M Unitek™) were stretched at different speeds in three groups: (1) static stretching test, (2) cyclic stretching test at a speed of 80 mm/min, and (3) cyclic stretching at a speed of 160 mm/min. A material tester and customized strain gauge were used to measure the residual force of the elastics in 37°C artificial saliva at different times. One-way repeated-measure analysis of variance followed by Scheffe's post-hoc comparison and t-test were used for statistical analysis. In Group 1, the force of the elastics degraded with time, with two separate phases being observed - distinctive degradation after 15 min and stabilization after 120 min. The cyclic stretching in Group 2 produced a significant deviation in the residual force and the initial force from the first minute, and stabilization after 300 min. After 1,440 min, 60% of the bands had snapped. Under accelerated stretching, no areas of relative stability were observed between the start of stretching to the start of breaking. After 1,440 high-speed stretches, 87% of the elastics in Group 3 snapped. These results indicate that the stretching speed affects the stability of the residual force of elastics. Cyclic stretching at high speed immediately induces a rapid degradation of the elastic's force and increases its probability of breakage. [ABSTRACT FROM AUTHOR]

Chemical manipulations of the implant surface produce a bactericidal feature to prevent infections around dental implants. Despite the successful use of bismuth against mucosal and dermis infections, the antibacterial effect of bismuth in the oral cavity remains under investigation. The aim of this study was to evaluate the antibacterial activities of bismuth compounds against Actinobacillus actinomycetemcomitans, Staphylococcus mutans, and methicillin-resistant Staphylococcus aureus (MRSA), and to investigate the antimicrobial effects of bismuth doped micro-arc oxidation (MAO) titanium via an agar diffusion test. Cell viability, alkaline phosphatase activity, and mineralization level of MG63 osteoblast-like cells seeded on the coatings were evaluated at 1, 7, and 14 days. The results demonstrate that bismuth nitrate possess superior antibacterial activity when compared with bismuth acetate, bismuth subgallate, and silver nitrate. The bismuth doped MAO coating (contained 6.2 atomic percentage bismuth) had good biological affinities to the MG63 cells and showed a higher antibacterial efficacy against Actinobacillus actinomycetemcomitans and MRSA, where the reduction rates of colony numbers is higher than that of the control group by 1.5 and 1.9 times, respectively. These in vitro evaluations demonstrate that titanium implants with bismuth on the surface may be useful for better infection control. [ABSTRACT FROM AUTHOR]

Titanium (Ti)-based materials are widely used in biomedical implant components and are applied successfully in various types of bone-anchored reconstructions. However, in dental implants the Ti materials contact not only bone but also gingival tissues, and are partially exposed to the oral cavity that includes bacteria. This study used titania and silver (TiO/Ag) compound coatings and zinc oxide (ZnO) films to enhance the antibacterial activity of the Ti-based implant. The hydrophobicity of each sample was examined by measuring the contact angle. Streptococcus mutans and human gingival fibroblast (HGF) was cultured on the coated samples, and the antibacterial effects and cell compatibility were determined using a Syto9 fluorescence staining and MTT methods. For the TiO/Ag samples, depositing Ag on the plate at a higher power (which increased the proportion of Ag) increased the contact angle and the hydrophobicity. The bacterial count was lowest for the 50 W TiO/Ag sample, which contained 5.9% Ag. The contact angles of the ZnO samples did not show the same tendency. The antibacterial effect was higher on ZnO-coated samples since bacterial count was threefold lower on ZnO samples as compared to control samples (Ti plate). From the MTT assay test, the mean optical density values for TiO/Ag-coated samples after 72 h of HGF adhesion were similar to the value obtained from the uncoated Ti. However, biocompatibility was lower on ZnO films than in control samples. Conclusively, the antibacterial activity was higher but the cell compatibility was lower on ZnO films than on TiO/Ag coatings. [ABSTRACT FROM AUTHOR]

Abstract: One of the major causes inducing loosening in the cementless acetabular cup implanting is its insufficient initial stability. In this study, three-dimensional finite element models of the pelvis and acetabular components were developed to investigate the relationship between relative micromotion, initial stability, and screw fixation under six daily activity loadings. A commercial available hemispheric cup with five screw holes was used as the target acetabular cup. The simulation results showed that if screws were placed closed together, when the screw number increased from 1 to 5, the peak micromotion decreased less than 14%, from 126.5 to 108.8μm, while the stable region, micromotion less than 28μm, enlarged only by 40%, from 46.1% to 64.7%. However, if the screw could be placed near the cup rim, a single rim screw, 202.1μm micromotion, could provide better stability than that of four dome screws, 209.6μm micromotion, placed closed together. To conclude, multiple cup screws should be placed near cup rim and as separate as possible to enlarge the stable region and reduce the peak micromotion between cup and acetabulum. [Copyright &y& Elsevier]

This study reports a method for controlling loads on an in vivo dental implant and its application for the investigation of early loading versus delayed loading of dental implants. The method was developed for the purpose of studying an ongoing hypothesis that amounts to bone loss around dental implants are related to mechanical-mediated adaptation of the alveolar bone. Using a customized intra-oral hydraulic system, the daily loading over a dental implant has been completed and recorded for six Sinclair swine. Each pig had a 5-month duration implant loading. During the experiments (loading), no analgesic treatment was supplied. The mean of the in vivo daily loadings was confirmed through an in vitro bench test after each animal was euthanized. Variations of the averaged loading input among the six animals were smaller than 10%. Preliminary data produced by the model suggests that cervical bone loss is less for early loading than for delayed loading. The current system is expected to provide a useful load control model for the study of alveolar bone adaptation around dental implants in relation to various loadings. [Copyright &y& Elsevier]