The Effect of Surface Treatment on Shear Bond Strength between Y-TZP and Veneer Ceramic: A Systematic Review and Meta-Analysis.

PURPOSE: The objective of this systematic review with meta-analysis was to evaluate surface treatment in yttria-stabilized tetragonal zirconia polycrystal ceramic (Y-TZP) on the shear bond strength (SBS) values between Y-TZP (core ceramic) and veneer ceramic, compared to untreated specimens. MATERIALS AND METHODS: This review was registered at PROSPERO platform under the number CRD42016036493. The systematic review of the extracted publications was performed to compare the effect of surface treatment on SBS between Y-TZP ceramic and veneering ceramic. A comprehensive review of the literature from the earliest available dates through January 2017 was performed in the PubMed/Medline, Embase, Scopus, and Cochrane Library databases. RESULTS: A total of 15 studies were identified for the inclusion of data, with only in vitro studies. A random-effect model found statistically significant differences between untreated and treated surfaces of Y-TZP (p < 0.00001; MD: 2.84; 95% CI: 2.19 to 3.49). In another analysis, a random-effect model found statistically significant differences between the groups that only performed the associations of treatments and control group (p < 0.00001; MD: 3.19; 95% CI: 2.11 to 4.28). CONCLUSIONS: Surface treatment in Y-TZP improved the values of SBS between the Y-TZP and veneer ceramic. The associations between two or more treatments also showed positive effect on the bond strength due the cumulative effect of the treatments.

Stress Analysis of Axial and Tilted Implants in Full-arch Fixed Dentures Under Different Abutment Conditions.

The aim of this study was to evaluate the stress distribution on full-arch prostheses, considering axial implants and tilted implants with or without abutments. Two photoelastic models were made, being that in 1 model the implants were inserted perpendicular, whereas in the other model 2 implants were inserted perpendicular and 2 implants were inserted with tilting 30° to the distal area. The prosthetic situations were evaluated: A-axial implants and nonsegmented full-arch prosthesis; B-axial implants and segmented full-arch prosthesis; C-tilted distal implants and nonsegmented full-arch prosthesis; D-tilted distal implants and segmented full-arch prosthesis, and was applied an axial load of 100 N at 5 points. The results showed greater stress concentration for axial implants than tilted implants in anterior and posterior loading. There was no difference in stress distribution to the use of abutment in the tilted implants. Shorter cantilever with tilted implants improved the stress distribution; the use of abutment did not influence the stress distribution.

An esthetics rehabilitation with computer-aided design/ computer-aided manufacturing technology.

AIM: This paper describes a case of a rehabilitation involving Computer Aided Design/Computer Aided Manufacturing (CAD-CAM) system in implant supported and dental supported prostheses using zirconia as framework. BACKGROUND: The CAD-CAM technology has developed considerably over last few years, becoming a reality in dental practice. Among the widely used systems are the systems based on zirconia which demonstrate important physical and mechanical properties of high strength, adequate fracture toughness, biocompatibility and esthetics, and are indicated for unitary prosthetic restorations and posterior and anterior framework. CASE DESCRIPTION: All the modeling was performed by using CAD-CAM system and prostheses were cemented using resin cement best suited for each situation. CONCLUSION: The rehabilitation of the maxillary arch using zirconia framework demonstrated satisfactory esthetic and functional results after a 12-month control and revealed no biological and technical complications. CLINICAL SIGNIFICANCE: This article shows the important of use technology CAD/CAM in the manufacture of dental prosthesis and implant-supported.

Analysis of the biomechanical behavior of short implants: The photo-elasticity method.

The aim of this study was to analyze the stress distribution of short implants supporting single unit or splinted crowns by the photo-elasticity method. Four photo-elastic models were produced: A (3.75×7 mm); B (3.75×7 mm, 3.75×7 mm and 3.75×7 mm); C (3.75×10 mm, 3.75×7 mm and 3.75×7 mm); D (3.75×13 mm, 3.75×7 mm and 3.75×7 mm). The prostheses were made with Ni-Cr alloy. A load of 100 N in the axial and oblique directions was applied, totaling 380 applications, individually capturing their images in each model. The data were randomized and analyzed qualitatively and quantitatively by 2 examiners. The oblique loading was significantly more damaging. The increase in length was favorable for stress distribution (p<0.05). The splinting was beneficial for the transmission of stresses mainly (p<0.05). The splinting of the crowns, as well as increasing the length of the first implant and axial loading was most beneficial in the stress distribution. Short splinted implants behaved better than single unit implants. Increasing of the length of the first implant significantly improved the stress distribution in all analyzed situations.

A 3-D finite element study of the influence of crown-implant ratio on stress distribution.

The purpose of this study was to assess the influence of the crown height of external hexagon implants on the displacement and distribution of stress to the implant/bone system, using the three-dimensional finite element method. The InVesalius and Rhinoceros 4.0 softwares were used to generate the bone model by computed tomography. Each model was composed of a bone block with one implant (3.75 x 10.0 mm) with external hexagon connections and crowns with 10 mm, 12.5 mm and 15 mm in height. A 200 N axial and a 100 N oblique (45°) load were applied. The models were solved by the NeiNastran 9.0 and Femap 10.0 softwares to obtain the results that were visualized by maps of displacement, von Mises stress (crown/implant) and maximum principal stress (bone). The crown height under axial load did not influence the stress displacement and concentration, while the oblique loading increased these factors. The highest stress was observed in the neck of the implant screw on the side opposite to the loading. This stress was also transferred to the crown/platform/bone interface. The results of this study suggest that the increase in crown height enhanced stress concentration at the implant/bone tissue and increased displacement in the bone tissue, mainly under oblique loading.