A systematic review and meta-analysis of the survival of non-feldspathic porcelain veneers over 5 and 10 years

PURPOSE: This systematic review aimed to report and explore the survival of dental veneers constructed from non-feldspathic porcelain over 5 and 10 years.

MATERIALS AND METHODS: A total of 4,294 articles were identified through a systematic search involving all databases in the Cochrane Library, MEDLINE (OVID), EMBASE, Web of Knowledge, specific journals (hand-search), conference proceedings, clinical trials registers, and collegiate contacts. Articles, abstracts, and gray literature were sought by two independent researchers. There were no language limitations. One hundred sixteen studies were identified for full-text assessment, with 10 included in the analysis (5 qualitative, 5 quantitative). Study characteristics and survival (Kaplan-Meier estimated cumulative survival and 95% confidence interval [CI]) were extracted or recalculated. A failed veneer was one which required an intervention that disrupted the original marginal integrity, had been partially or completely lost, or had lost retention more than twice. A meta-analysis and sensitivity analysis of Empress veneers was completed, with an assessment of statistical heterogeneity and publication bias. Clinical heterogeneity was explored for results of all veneering materials from included studies.

RESULTS: Within the 10 studies, veneers were fabricated with IPS Empress, IPS Empress 2, Cerinate, and Cerec computer-aided design/computer-assisted manufacture (CAD/CAM) materials VITA Mark I, VITA Mark II, Ivoclar ProCad. The meta-analysis showed the pooled estimate for Empress veneers to be 92.4% (95% CI: 89.8% to 95.0%) for 5-year survival and 66% to 94% (95% CI: 55% to 99%) for 10 years. Data regarding other non-feldspathic porcelain materials were lacking, with only a single study each reporting outcomes for Empress 2, Cerinate, and various Cerec porcelains over 5 years. The sensitivity analysis showed data from one study had an influencing and stabilizing effect on the 5-year pooled estimate.

CONCLUSION: The long-term outcome (> 5 years) of non-feldspathic porcelain veneers is sparsely reported in the literature. This systematic review indicates that the 5-year cumulative estimated survival for etchable non-feldspathic porcelain veneers is over 90%. Outcomes may prove clinically acceptable with time, but evidence remains lacking and the use of these materials for veneers remains experimental.

A chemically unlocked binary molecular switch

A highly luminescent and sensitive terbium complex of a ligand comprising of a phthalimide group appended to a DO3A moiety is an active pH sensor that is conditional on its previous pH. © 2012 The Royal Society of Chemistry.

Structure-tunable Janus fibers fabricated using spinnerets with varying port angles

The preparation of Janus fibers using a new side-by-side electrospinning process is reported. By manipulating the angle between the two ports of the spinneret emitting the working fluids, Janus nanofibers with tunable structures in terms of width, interfacial area and also volume of each side can be easily fabricated.

Chloride induced corrosion of steel bars in alkali activated slag concretes

The studies on chloride induced corrosion of steel bars in alkali activated slag (AAS) concretes are scarcely reported in the past. In order to make this issue clearer and compare the corrosion performance of AAS with Portland cement (PC) counterpart, an investigation was carried out and the results are reported in this paper. Corrosion properties were assessed with the help of rate of corrosion, electrical resistivity and pore solution chemistry. It was found that: (i) steel corrosion resistance of the AAS concretes was comparable or in some cases even worse than that of Portland cement (PC) concrete under intermittent chloride ponding regime; (ii) the corrosion behaviour of the AAS concretes was significantly influenced by ionic exchange, carbonation and sulphide concentration; (iii) the increase of alkali concentration of the activator generally reduced chloride resulting corrosion, and a value of 1.5 was found to be an optimum modulus for the activator for improving the corrosion resistance.

Effect of reinforcement and heat treatment on elevated temperature sliding of electroless Ni–P/SiC composite coatings

The investigation is focused on the wear behaviour at elevated test temperature of composite Ni–P/SiC deposit, with varying concentration of the reinforcing SiC particles. The phase evolution measured by X-ray diffraction suggests slight crystallisation during wear testing at 200 °C. In coating without reinforcing particles, adhesive wear is accompanied by microcracks. The thermal heat generated and the cyclic loading could have induced sub-surface microcracks. Owing to the effective matrix-ceramics system in composite coatings, fine grooves, abrasive polishing and uniform wearing are observed. Reinforcing particles in the matrix hinder microcrack formation and significantly reduce the wear rate. Triboxidation is confirmed from energy dispersive X-ray spectrometry.

Modelling and visualisation of material flow in friction stir spot welding

Abstract The material flow in friction stir spot welding of aluminium to both aluminium and steel has been investigated, using pinless tools in a lap joint geometry. The flow behaviour was revealed experimentally using dissimilar Al alloys of similar strength. The effect on the material flow of tool surface features, welding conditions (rotation speed, plunge depth, dwell time), and the surface state of the steel sheet (un-coated or galvanized) have been systematically studied. A novel kinematic flow model is presented, which successfully predicts the observed layering of the dissimilar Al alloys under a range of conditions. The model and the experimental observations provide a consistent interpretation of the stick-slip conditions at the tool-workpiece interface, addressing an elusive and long-standing issue in the modelling of heat generation in friction stir processing.