Development of Rapid Bioactivity-Expressed Zr-50Ti Alloys by Surface Treatment with Modified Simulated Body Fluid

Zr-50Ti alloys are promising biomaterials due to their excellent mechanical properties and low magnetic susceptibility. However, Zr-50Ti alloys do not inherently bond well with bone. This study aims to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic implant materials. Initially, the surface of Zr-50Ti alloys was treated with a sulfuric acid solution to create a microporous structure, increasing surface roughness and area. Subsequently, low crystalline calcium phosphate (L-CaP) precipitation was controlled by adding Mg2+ and/or CO32- ions in modified simulated body fluid (m-SBF). The treated Zr-50Ti alloys were then subjected to cold isostatic pressing to force m-SBF into the micropores, followed by incubation to allow L-CaP formation. The apatite-forming process was tested in simulated body fluid (SBF). The results demonstrated that the incorporation of Mg2+ and/or CO32- ions enabled the L-CaP to cover the entire surface of Zr-50Ti alloys within only one day. After short-term soaking in SBF, the L-CaP layer, modulated by Mg2+ and/or CO32- ions, formed a uniform hydroxyapatite (HA) coating on the surface of the Zr-50Ti alloys, showing potential for optimized bone integration. After soaking in SBF for 14 days, the bonding strength between the apatite layer and alloy has the potential to meet the orthopedic application requirement of 22 MPa. This study demonstrates an effective method to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic applications.

Evaluation of Adhesion and Viability of Human Gingival Fibroblasts on Strontium-Coated Titanium Surfaces: an in vitro Study

Background

Applying multifunctional coatings employing strontium (Sr) ions on titanium (Ti) surfaces is a useful and biocompatible method to improve osseointegration and prevent tissue infections through antimicrobial activity. Nonetheless, the effectiveness of Sr coating on the adhesion and viability of human gingival fibroblasts (HGFs) to Ti surfaces remains unclear.

Purpose

The study aimed to evaluate the effect of Sr coating on the adhesion and viability of HGFs to Ti surfaces.

Materials and Methods

The Ti wafers were divided into two groups based on Sr coating: uncoated Ti (control) and Sr-coated Ti. The Magnetron sputtering technique was used for Sr coating on Ti surfaces. The HGFs were seeded onto the surfaces and cultured for 48 and 96 hours before the cell adhesion and viability of the attached HGFs were assessed. The adhesion of HGFs was analyzed using the attached cell numbers at 48 h and 96 h, and the morphology at 24 h and 72 h. The cytotoxic effect on HGFs was assessed after 24 and 72 hours of incubation using cell viability assay. Student's t-test was used for statistical analysis.

Results

The number of cells attached to Sr-coated surfaces was significantly greater than those attached to uncoated Ti surfaces after 48 hours (P<0.0001) and 96 hours (P=0.0002). Sr-coated and uncoated Ti surfaces were not cytotoxic to HGFs, with the cell viability ranging from 92% to 105% of the untreated control HGFs. There were no significant differences in cell viability between Sr-coated and uncoated Ti surfaces at 24 hours (P=0.3675) and 72 hours (P=0.0982).

Conclusion

Sr-coated Ti surfaces induce adhesion of HGFs compared to uncoated Ti surfaces. Further, Sr-coated and uncoated Ti surfaces show no cytotoxic effect on the attached HGFs.

Mechanical stability of angulated zirconia abutments supporting maxillary anterior single crowns on narrow-diameter implants

OBJECTIVES

To investigate the fracture strength of angulated hybrid abutments supporting anterior single crowns on narrow-diameter implants (NDIs).

MATERIAL AND METHODS

Zirconia abutment with angulations of labial inclination 0° (TZ0Z), 15° (TZ15Z), 30° (TZ30Z) and palatal inclination 15° (TZ - 15Z) was designed on 3.3-mm titanium-zirconium (Ti-Zr) NDIs. Titanium abutment connected with Ti-Zr implant (TZ0T) and 0° zirconia abutment connected with pure titanium (Ti) implant (T0Z) were control groups. Thirty-six un-restored abutments and 36 abutments restored with highly translucent zirconia (HTZ) crowns were tested. Failure loads were compared among 6 groups, and bending moments were calculated for comparison between un-restored and restored abutments.

RESULTS

Failure loads of un-restored abutments were affected by the abutment angle. Sixty-seven percent samples in TZ30Z and 83% samples in TZ - 15Z group fractured at the thinnest part of the zirconia abutment and exhibited lower failure load (p < .05). Failure loads of restored abutments were close to or exceeded the maximum bite force of anterior teeth, and no differences were found among six groups (p > .05). Except TZ15Z and TZ0T group, the bending moment increased with the crown construction, especially for TZ30Z and TZ - 15Z groups (p < .001).

CONCLUSIONS

The fracture strength of hybrid abutments restored with HTZ crown on Ti-Zr NDIs exceeded the bite forces of anterior teeth for all the groups and were not affected by the abutment angle.

CLINICAL RELEVANCE

In terms of fracture strength, Ti-Zr NDIs combined with angulated hybrid abutments and HTZ crowns can be used in the anterior region.

A Novel Design to Optimize Biomechanical Properties of Dental Implant

Objective: The main objective of this study is to evaluate a novel design to optimize dental implant biomechanics. According to this objective, evaluations of the resilient implant design which aimed to mimic biomechanical behaviors of natural tooth have been made and outcomes were compared with natural tooth and standard dental implants with using 3D hyper-elastic finite element analysis. Methods: Models used in the study corresponding to conventional dental implant, natural tooth and resilient dental implant design. Hyperelastic model analysis were performed for close presentment of mechanical behaviors of resilient materials like periodontal ligament and medical silicone. Top values of maximum principal stress, minimum principal stress of surrounding bone and displacement of each model were evaluated under axial and non-axial loading conditions with magnitude of 30N, 80N and 100N. Results: Outcomes of finite element study showed reduction on maximum principal stress and minimum principal stress levels with the use of resilient dental implant comparing to the standard implant model. Standard implant model had been observed notably rigid in all loading conditions compared to the other models. Resilient implant model showed similar biomechanical characteristics with natural tooth model within the limitations of this study. Conclusion: According to finite element analysis results; resilient implant design was able to resolve some biomechanical discrepancies and seem to have adequate biomechanical similarity with natural tooth under both axial and non-axial loading conditions.

Clinical Performance Comparing Titanium and Titanium–Zirconium or Zirconia Dental Implants: A Systematic Review of Randomized Controlled Trials

Objectives: This study aimed to compare clinical results between titanium (Ti), zirconia (Zr), or titanium–zirconium (TZ) dental implants and to analyze survival rate (SR), bleeding on probing (BoP), marginal bone loss (MBL), and/or probing depth (PD). Data source: Manual and electronic searches were conducted (PubMed and Web of Science) to identify randomized controlled trials that compared the outcomes of at least two implant types (control and test group) within the same study. The focused question was determined according to the PICOT strategy. Seven studies were included out of 202 research studies initially found. The follow-up periods ranged from 12 to 80 months, and the mean age was from 43.3 to 65.8 years old. The SR for Ti, TZ, and Zr implants ranged from 92.6% to 100%, 95.8% to 100%, and 87.5% to 91.25%, respectively; MBL for Ti, TZ, and Zr implants varied from −1.17 mm to −0.125 mm for Ti, −0.6 mm to −0.32 mm for TZ, and −0.25 mm to −1.38 mm for Zr. Studies showed a low incidence of mucositis and peri-implantitis; however, BoP for Zr was 16.43%, Ti ranged between 10% and 20%, and TZ from 10% to 13.8%. PD for Ti ranged from 1.6 mm to 3.05 mm, TZ was 3.12 mm (only one study), and Zr ranged from 2.21 mm to 2.6 mm. Conclusion: All three types of implants showed similar tissue behavior. However, the TZ group had better results when compared with Ti and Zr for SR, MBL, and BoP, except for PD. Furthermore, the worst SR was found in the Zr implants group.

Impact of scandium on mechanical properties, corrosion behavior, friction and wear performance, and cytotoxicity of a β-type Ti-24Nb-38Zr-2Mo alloy for orthopedic applications

β-type titanium (Ti) alloys have been extensively investigated as orthopedic implant materials due to their unique combination of low elastic modulus, high specific strength, corrosion resistance, and biocompatibility. In this study the mechanical properties, corrosion behavior, friction and wear performance, and cytotoxicity of β-type Ti-24Nb-38Zr-2Mo (TNZM) and Ti-24Nb-38Zr-2Mo-0.1Sc (TNZMS) have been comparatively investigated for orthopedic applications. Cold-rolling (CR) and cold-rolling plus solution-treatment (CR+ST) were performed on the as-cast (AC) alloys and their microstructures and material properties were characterized. The impact of Sc addition on the mechanical and corrosion properties, friction and wear behavior, and in vitro cytocompatibility of the TNZMS alloy was assessed. The CR+ST TNZMS alloy exhibited the best combination of properties among all the alloy samples, with a yield strength of 780 MPa, ultimate strength of 809 MPa, elongation of 19%, Young's modulus of 65.4 GPa, and hardness of 265 HV. Electrochemical testing in Hanks' Solution indicated that the CR+ST TNZMS sample also showed the highest corrosion resistance with a corrosion potential of -0.234 V, corrosion current density of 0.07 µA/cm², and corrosion rate of 1.2 µm/y. Friction and wear testing revealed that the TNZMS alloy showed higher wear resistance compared to the TNZM alloy and the wear resistance of the different samples was ranked CR > CR+ST > AC. Finally, both the CR+ST TNZM and TNZMS showed no-cytotoxicity towards MG-63 cells and the TNZMS exhibited slightly higher cytocompatibility than the TNZM alloy. STATEMENT OF SIGNIFICANCE: This work reports the β-type Ti-24Nb-38Zr-2Mo (TNZM) and Ti-24Nb-38Zr-2Mo-0.1Sc (TNZMS) alloys fabricated by as-cast (AC), cold-rolling (CR), and cold-rolling plus solution-treatment (CR+ST) for potential orthopedic applications. The experimental results showed that the TNZMS alloy exhibited significantly enhanced mechanical, wear, and corrosion properties than those of TNZM alloy; and the CR+ST TNZMS possess a unique combination of the best mechanical and corrosion properties including a yield strength of 780 MPa, ultimate strength of 809 MPa, elongation of 19%, Young's modulus of 65.4 GPa, and corrosion rate of 1.2 µm/y in Hanks' Solution. Both the CR+ST TNZM and TNZMS alloys exhibited non-cytotoxicity towards MG-63 cells and TNZMS showed a higher cytocompatibility than that of TNZM.

Materials Sealing Preventing Biofilm Formation in Implant/Abutment Joints: Which Is the Most Effective? A Systematic Review and Meta-Analysis

The purpose of this systematic review was to evaluate the literature available for materials exhibiting the best efficacy in preventing biofilm formation in the interior of implants. We searched PubMed/MEDLINE, Scopus, and Cochrane databases. This review is registered with the PROSPERO database and followed the suitability of the PRISMA protocol. The initial search resulted in 326 articles from the databases. After they were read, 8 articles remained, and the inclusion and exclusion criteria were applied. Six of these 8 articles were classified as in vitro and 2 were classified as in situ. The regions of the implants evaluated ranged from the interface of the pieces to the occlusal upper access of the abutment. The implant connections evaluated the Morse taper, external connection, and internal connection. Meta-analysis of the quantitative data was performed at a significance level of .05. Cotton exhibited poor control of infiltration, even in combination with other materials. Isolated gutta-percha (GP) and polytetrafluoroethylene (PTFE) tape with composite resin (CR) or GP performed better as physical barriers. The best results for chemical barriers were observed by the application of 1% chlorhexidine gluconate (CG) gel, thymol varnish, and the deposition of Ag films onto the surface. The applied meta-analysis did not show a significant difference in comparison between the different types of implant connections (P > .05). The application of CG and thymol varnish antimicrobials was effective in preventing biofilm formation and easy clinical execution; these could be used in combination with CR, GP, and PTFE.