热压铸全瓷高嵌体应用于前磨牙修复的临床研究

目的 评价IPS e.max press热压铸全瓷高嵌体在前磨牙修复中的临床效果.方法 选择经完善根管治疗的102颗牙冠缺损的前磨牙,制作IPS e.max press热压铸全瓷高嵌修复体,追踪观察36个月.结果 102件IPS e.max press热压铸全瓷高嵌体仅1件修复失败,成功率为99.02％.结论 IPS e.max press热压铸全瓷高嵌体修复前磨牙具有良好的修复效果,值得推广.     

An evaluation of wear of human enamel opposed by ceramics of different surface finishes

Statement of Problem:

Surface of porcelain restoration is a matter of clinical concern because of its abrasive action on the opposing enamel.

Purpose:

This study comparatively evaluated wear of enamel when opposed by three different surface finishes of ceramic.

Materials and Methods:

A total of 60 metal-ceramic discs (10 mm × 2 mm) with different surface finishes were fabricated. They were divided into four groups of autoglazed ceramic surface, over glazed ceramic surface, ceramic surface polished with Shofu polishing kit and ceramic surface polished with DFS polishing wheels and paste. Each group comprised of 15 discs. Sixty human teeth samples were prepared from freshly extracted, unrestored, caries free, nonattrited maxillary first premolars. Each tooth sample was weighed before wear testing using AT200 Mettler Toledo electronic analytical balance of 0.0001 g accuracy. Occlusal surfaces of these teeth were then abraded against the substrates in a wear machine for a total of 10,000 cycles. Each tooth sample was weighed after 5000 cycles and after the total of 10,000 cycles, respectively, using the same balance. Differences in weight of tooth samples before and after wear testing were evaluated statistically using one-way analysis of variance and Bonferroni''s correction for multiple group comparisons.

Results:

The values obtained for percentage weight loss after 10,000 cycles for over glazed ceramic surface were marginally higher than values obtained for autoglazed surface. It was observed that values obtained for percentage weight loss by polished ceramic after 10,000 cycles were statistically less as compared to the values obtained with autoglazed and over glazed ceramic surface (P < 0.001). There was no statistically significant difference between the values obtained by polished ceramic surfaces of two different groups.

Conclusion:

Enamel wear produced by polished porcelain is substantially less than autoglazed and over glazed porcelain. No significant difference was found in enamel wear when opposed by ceramic surfaces polished by two different methods. This study indicates the potential damage porcelain can inflict upon enamel and suggests that porcelain should be polished instead of over glazed.     

Maxillary Midline diastema closure after replacement of primary teeth with implant prosthesis

This case shows an excellent esthetic treatment outcome using implant‐retained crowns replacing maxillary laterals and canines in hypodontia patient with unusual incidence of spontaneous diastema closure after the placement of implants. To our knowledge, this is the first case report showing maxillary midline diastema closure after implant placement.     

Structural Ceramics Modified by Water Treatment Plant Sludge

Water treatment plant (WTP) sludge is actively used in building materials production. The object of this research was modifying additives for ceramic bricks from WTP aluminium-containing sludge. The research aim of this study was to determine the suitability of a million-plus population city’s WTP sludge as a burning-out additive in the production of structural ceramics and to establish the optimal conditions for obtaining products with the best characteristics. The raw water belongs to water belongs to the hydrocarbonate class, the calcium group, and it is of low turbidity (1.5–40 mg/L kaolin). Sludge, sourced from WTP sedimentation tanks, was dewatered by adding lime or by using the freezing-thawing method. The spray-dried WTP sludge is introduced into the clay in amounts of 5% to 20% by weight. The addition of 20% reduces the sensitivity of the clay to drying, reduces the density of ceramic by 20% and simultaneously increases its compressive strength from 7.0 to 10.2 MPa. The use of WTP sludge as a modifying additive, pretreated by the freezing-thawing method, makes it possible to obtain ceramic bricks with improved properties. The results can be used for WTP sludge containing aluminium obtained by treating water of medium turbidity and medium colour.     

Development of Scheelite Tailings-Based Ceramic Formulations with the Potential to Manufacture Porcelain Tiles,Semi-Stoneware and Stoneware

New ceramic formulations based on scheelite tailing were developed, and their potential in the ceramic industry was evaluated. Green bodies with different contents of scheelite tailing (0–8 wt%) were sintered (1150 °C, 1200 °C, and 1250 °C) and characterized in terms of the main mineralogical phases, microstructure, and physico-mechanical properties. The mullite was the main phase identified in all sintered temperatures. This result was also ratified with the aid of scanning electron microscope (SEM) images, in which small needles of the mullite were detected. The presence of mullite is required because it contributes to increasing the mechanical resistance of the material. The physico-mechanical properties measured (water absorption, linear shrinkage, apparent porosity, and flexural strength) were compared to the ISO 13006, and the samples sintered at 1150 °C presented potential to be used as semi-stoneware, while those sintered at 1200 °C and 1250 °C can be employed stoneware and porcelain tiles, respectively.     

Silane influence on bonding to CAD-CAM composites: An interfacial fracture toughness study

ObjectivesTo evaluate silane influence on the interfacial fracture toughness (IFT) of composite cement, with the two sub-classes of CAD-CAM composites, polymer-infiltrated ceramic networks (PICN) and dispersed fillers (DF), after hydrofluoric acid etching (HF) or airborne-particle abrasion (AB). A secondary objective was to correlate results with developed interfacial area ratio (Sdr) and surface wettability.MethodsExperimental PICN and DF blocks were cut into equilateral half-prisms, which were treated with HF or AB, then treated with an experimental silane or not and bonded to their counterparts with an experimental light-cure resin cement. After thermocycling, samples (n = 30 per group) were tested for IFT using the notchless triangular prism test in a water bath at 36 °C. Moreover, profilometry and contact angle measurement were performed on rectangular samples of each group. Finally, bonding interface was analysed by SEM.ResultsPICN-HF treated with silane showed the highest IFT significantly. Three-way ANOVA revealed the influence of silane, material class and surface pre-treatment (HF or AB) on IFT (p < 0.05). When silane was used, IFT was correlated with Sdr, while surface wettability was increased. Silane application significantly increased IFT for PICN but not for DF, while PICN performed better with HF and DF with AB.SignificanceSilane increases IFT of composite cement with PICNs, but not with DF materials. Results suggest that silane increases the micromechanical bond by promoting resin cement spreading and penetration in surface roughness. This roughness is significantly higher for pre-treated PICNs than for DF due to their specific honeycomb microstructure when etched, which explains their better bonding properties.