Application of Ce-TZP/Al 2 O 3 nanocomposite to the framework of an implant-fixed complete dental prosthesis and a complete denture

Complete denture fabrication with polyetherketoneketone as a framework material: A clinical report

This clinical report describes the fabrication of conventional complete dentures with polyetherketoneketone (PEKK) frameworks made with computer-aided design and computer-aided manufacturing (CAD-CAM). No biologic or prosthetic complications were observed at the 1-year follow-up.

Laser-Milled Microslits Improve the Bonding Strength of Acrylic Resin to Zirconia Ceramics

Heightened aesthetic considerations in modern dentistry have generated increased interest in metal-free “zirconia-supported dentures.” The lifespan of the denture is largely determined by the strength of adhesion between zirconia and the acrylic resin. Thus, the effect on shear bond strength (SBS) was investigated by using an acrylic resin on two types of zirconia ceramics with differently sized microslits. Micromechanical reticular retention was created on the zirconia surface as the novel treatment (microslits (MS)), and air-abrasion was used as the control (CON). All samples were primed prior to acrylic resin polymerization. After the resin was cured, the SBS was tested. The obtained data were analyzed by using multivariate analysis of variance(α = 0.05). After the SBS test, the interface failure modes were observed by scanning electron microscopy. The MS exhibited significantly higher bond strength after thermal cycles (p < 0.05) than the CON. Nevertheless, statistically comparisons resulted in no significant effect of the differently sized microslits on SBS (p > 0.05). Additionally, MS (before thermal cycles: 34.8 ± 3.6 to 35.7 ± 4.0 MPa; after thermal cycles: 26.9 ± 3.1 to 32.6 ± 3.3 MPa) demonstrated greater SBS and bonding durability than that of CON (before thermal cycles: 17.3 ± 4.7 to 17.9 ± 5.8 MPa; after thermal cycles: 1.0 ± 0.3 to 1.7 ± 1.1 MPa), confirming that the micromechanical retention with laser-milled microslits was effective at enhancing the bonding strength and durability of the acrylic resin and zirconia. Polycrystalline zirconia-based ceramics are a newly accessible material for improving removable prosthodontic treatment, as the bond strength with acrylic resin can be greatly enhanced by laser milling.

Effect of the Compositions on the Biocompatibility of New Alumina-Zirconia-Titania Dental Ceramic Composites

Dental implant biomaterials are expected to be in contact with living tissues, therefore their toxicity and osseointegration ability must be carefully assessed. In the current study, the wettability, cytotoxicity, and genotoxicity of different alumina-zirconia-titania composites were evaluated. The surface wettability determines the biological event cascade in the bioceramic/human living tissues interface. The measured water contact angle indicated that the wettability strongly depends on the ceramic composition. Notwithstanding the contact angle variability, the ceramic surfaces are hydrophilic. The cytotoxicity of human gingival fibroblast cells with materials, evaluated by an (3-(4,5 methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) test, revealed an absence of any cytotoxic effect. A relationship was found between the cell viability and the wettability. It was subsequently deduced that the cell viability increases when the wettability increases. This effect is more pronounced when the titania content is higher. Finally, a comet test was applied as complementary biocompatibility test to detect any changes in fibroblast cell DNA. The results showed that the DNA damage is intimately related to the TiO₂ content. Genotoxicity was mainly attributed to ceramic composites containing 10 wt.% TiO₂. Our research revealed that the newly developed high performance alumina-zirconia-titania ceramic composites contain less than 10 wt.% TiO₂, and display promising surface properties, making them suitable for dental implantology applications.

Reduction in maxillary complete denture deformation using framework material made by computer-aided design and manufacturing systems

The aim of this study was to investigate the effects of framework materials manufactured by dental CAD/CAM systems on complete denture deformation. Four materials were used for the maxillary complete denture framework: fiber-reinforced composite (FRC), nano-zirconia (N-Zr), cobalt-chromium-molybdenum alloy (CCM), and polyether-ether-ketone (PEEK). The framework materials were prepared using CAD/CAM systems. Six dentures of each material were fabricated, using polymethyl-methacrylate (PMMA) as a control. The thickness of the palatal area was 1.0 mm for PMMA and PEEK and 0.5 mm for FRC, N-Zr, and CCM. The denture deformation during occlusal load was monitored using four rosette strain gauges placed on the midline of the denture. The maximum principal strain (MPS) of each gauge, except that at the labial frenum, increased proportionally with increasing applied load. The directions of MPS were predominantly perpendicular to the midline of the denture. When a 200-N load was applied, the MPS at the incisive papilla in N-Zr and CCM was half that of PMMA; there was no significant difference among MPSs of PEEK, PMMA and FRC. The MPS at the end point of the denture in FRC, N-Zr, and CCM was significantly smaller than that of PMMA. The MPSs of the complete denture decreased when the CAD/CAM fabricated framework was used. The effects of the CAD/CAM fabricated framework on complete denture deformation varied due to the material used; however, a CAD/CAM fabricated framework material is considered to be effective for reducing complete denture deformation.

Titanium removable denture based on a one-metal rehabilitation concept

The use of a single metal for all restorations would be necessary because it protects against metal corrosion caused by the contact of different metals. For this "one-metal rehabilitation" concept, non-alloyed commercially pure (CP) titanium should be used for all restorations. Titanium frameworks have been cast and used for the long term without catastrophic failure, whereas they have been fabricated recently using computer-aided design/computer-aided manufacturing (CAD/CAM). However, the milling process for the frameworks of removable partial dentures (RPDs) is not easy because they have very complicated shapes and consist of many components. Currently, the fabrication of RPD frameworks has been challenged by one-process molding using repeated laser sintering and high-speed milling. Laser welding has also been used typically for repairing and rebuilding titanium frameworks. Although laboratory and clinical problems still remain, the one-metal rehabilitation concept using CP titanium as a bioinert metal can be recommended for all restorations.