A retrospective study of 12,538 internal conical connection implants focused on the long-term integrity of implant-abutment complexes.

OBJECTIVE: To evaluate the long-term integrity of implant-abutment complexes in implant systems with two internal conical angles. MATERIAL AND METHODS: 12,538 bone-level implants of two systems placed between January 2012 and December 2018 were retrospectively analyzed. Cumulative abutment/implant fracture rates in systems with larger (LA, 7.5°) and smaller (SA, 5.7°) internal conical angles were estimated using the Kaplan-Meier analysis and compared between groups. The association between implant systems and jammed abutment retrievability was evaluated by multivariable generalized estimating equation logistic regression modeling. RESULTS: For LA, the 8-year cumulative incident rate was 0.10% (95% confidence interval (CI): 0-0.24%) for implant fracture and 0.26% (95% CI: 0.11%-0.41%) for abutment fracture, demonstrating a significant difference in gender (p = .03), implant diameter (p = .01), jaw (p = .006), and antagonist tooth (p < .001). For SA, the 8-year cumulative incident rate was 0.38% (95% CI: 0-0.79%) for implant fracture and 2.62% (95% CI: 0.05%-5.13%) for abutment fracture, which was influenced by implant diameter (p < .001) and site (p = .03). The cumulative implant/abutment fracture rate was lower for LA implants, particularly for LA implant-supported single crowns (SCs) (p < .05). The abutment-retrieval success rate was 92.9% for LA and 57.1% for SA (p = .055). CONCLUSION: LA implants exhibited a lower incidence of fracture in abutment-implant complexes and a relatively higher retrievability success rate for jammed abutments.

Development and properties of dental Ti-Zr binary alloys.

In this study, two medium Zr-containing Ti-based alloys with commercially pure titanium as control were systematically investigated to assess their potential biomedical application. After samples subjected to TMP and CR, it was found that the Zr addition significantly affected the microstructure, phase constitutions, mechanical properties and cytocompatibility. The microstructural results showed that increasing Zr concentrations resulted in more refined grains. Furthermore, Zr changed the phase constitution: CR Ti-20Zr was formed by the single α-phase while CR Ti-30Zr alloy was formed by the coexistence of α and deformation-induced FCC phases. The P-type FCC phase was dominant and more prone to occur than the B-type one. The mechanical tests demonstrated that the increasing Zr content led to a simultaneous increase in micro-hardness, strength and plasticity of CR samples due to the combined effects of solution strengthening, work hardening and the FCC phase. The SEM fractography indicated that the brittle fracture of CR Ti-20Zr due to deformation twins and ductile fracture of CR Ti-30Zr because of FCC phase. Furthermore, Ti-Zr alloys presented comparable cytocompatibility to the CP-Ti control based on cell viability, proliferation and intracellular O2- content of MSCs. Specifically, alkaline phosphatase activity in BMSCs were significantly higher for grain refined CR Ti-30Zr. Considering all these results, CR Ti-30Zr alloy exhibited the optimal comprehensive performance to be potential dental materials.

Polymer shell as a protective layer for the sandwiched gold nanoparticles and their recyclable catalytic property.

Poly(ethyleneglycol methacrylate) (PEGDMA) shell was used as a protective layer for the sandwiched gold nanoparticles, which were prepared through the in situ reduction in the HAuCl4 precursor in the presence of (aminopropyl)trimethoxysilane (APS) modified silica/PEGDMA core-shell microspheres. In this process, the silica/PEGDMA core-shell microspheres were afforded by the distillation-precipitation polymerization of the EGDMA monomer on the APS-modified silica particles with the aid of hydrogen-bonding interaction. The gold nanoparticles were formed at the interface between the silica core and the PEGDMA outer layer through the strong coordinate interaction between the gold nanoparticles and the amino groups on the surface of the silica during the reduction in HAuCl4. The sandwiched gold nanoparticles exhibited highly catalytic efficiency and facile recovery with good stability.