Evaluation of a virtual reality simulation system for porcelain fused to metal crown preparation at Tokyo Medical and Dental University. (57/65)

The use of virtual reality simulation (VRS) is a new teaching modality in dentistry, and there is scope for further research evaluating its use under different educational programs. The purpose of this study was to evaluate how VRS with or without instructor feedback influenced students' learning and skills related to porcelain fused to metal (PFM) crown preparation. In this study, forty-three dental students in their fifth year of study at Tokyo Medical and Dental University, Tokyo, Japan, were randomly divided into three groups: the first group used VRS (DentSim) with the instructor's feedback (DSF) (n=15), the second group used VRS without the instructor's feedback (DS) (n=15), and the third group neither used features of VRS (NDS) (n=13) nor received the instructor's feedback. All the students performed PFM crown preparation under the same setup once a week for four weeks. Total scores, preparation time, and twelve evaluation items were compared among the three groups and four experiments. The total scores of students in the DSF and DS groups were significantly higher than those in the NDS group. The presence of the instructor did not result in significant difference when VRS was used for training, while it shortened the preparation time at early stages. The results of this study suggested that the use of the VRS system improved student training for PFM crown preparation.  (+info)

Tooth wear against ceramic crowns in posterior region: a systematic literature review. (58/65)


Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients. (59/65)


Diffusion of elements in porcelain into titanium oxide. (60/65)

The diffusion of elements of commercial porcelain for titanium into titanium oxide during heating was investigated. Titanium was deposited on three kinds of disk-shaped porcelains by vacuum-vaporization and the porcelains were then heated. A thin titanium oxide film was formed on the porcelains by the heating. X-ray photoelectron spectroscopy was used to characterize the surfaces of the porcelains with and without titanium oxide. Only sodium, potassium, and barium diffused into titanium oxide during heating, where they formed a complex oxide with titanium. The diffusion of these elements may be involved in the bonding of porcelain to titanium.  (+info)

Experimental studies on the application of a porcelain-light-cured resin matrix system to the porcelain margin of metal-ceramic crowns. (61/65)

Application of a light-cured porcelain margin is a technique which has been developed recently. In this study, we compared the porcelain margin properties of the porcelain-light-cured resin matrix system and the traditional porcelain-water system, in terms of volumetric shrinkage, density, compressive strength, surface characteristics, internal porosity, separability of the condensed porcelain from the stone die, and the marginal integrity. The experimental resin matrix was composed of BDMA or EGDMA as a base monomer, CQ as a photoinitiator, DEAEMA as a polymerization accelerator, and TEGDMA as a diluent. Compared with the conventional system, the porcelain of the resin matrix system tended to show a larger volumetric shrinkage, a smaller density and a lower compressive strength. The experimental groups containing the diluent and the traditional control group demonstrated smoother surfaces and less internal porosity than those without the diluent. The photoinitiator was thought to play an important role on the separability from the stone die and the marginal integrity; the higher the ratio of the photoinitiator (1.0 wt%), the better the separability and the fit.  (+info)

Effect of barium in porcelain on bonding strength of titanium-porcelain system. (62/65)

The bonding strength to titanium, thermal expansion, and bending strength of glassy porcelain containing barium of 5, 10, and 15 mass% were estimated and compared with those of barium-free porcelain, to estimate the effect of barium content on bonding strength to titanium. The three different glassy porcelains containing barium were made by melting at 950 degrees C. The bonding strength of a commercial porcelain to titanium increased with the addition of barium. Bending strength and thermal expansion were not affected by the barium content. Therefore, the addition of barium to porcelain is effective for strengthening the bonding of porcelain to titanium.  (+info)

Glazing and finishing dental porcelain: a literature review. (63/65)

BACKGROUND: Dental porcelain has found an increased number of applications in recent years with the development of new methods for the construction of porcelain veneers and intracoronal restorations. In addition, it is used in metal-ceramic and all-porcelain crowns and bridges for the restoration of anterior and posterior teeth. METHODS: This paper presents a review of a number of studies that have examined the visual and microscopic appearance and roughness of glazed, unglazed and polished porcelain surfaces using techniques such as, scanning electron microscopy and surface profilometry. FINDINGS: All have agreed that glazed porcelain provides a smooth and dense surface. Many have shown that polishing can produce an equally smooth surface, which may even be esthetically better. Some studies supported the use of polishing as an alternative to glazing. However, reports have shown that unglazed porcelain is more abrasive than glazed. CLINICAL SIGNIFICANCE: This paper aims to guide general practitioners in the proper polishing of adjusted porcelain in the dental office. The recommendations of various authors are summarized in Table I.  (+info)

Soft tissue transfer models: the patient-dentist-laboratory connection. (64/65)

The dental technician must have an accurate impression of gingival contour, in order to apply porcelain correctly to a metal-ceramic restoration. This article describes a technique for making an accurate model of the soft tissues around a restoration. The technique involves taking a transfer impression and making a soft tissue model.  (+info)