Marginal adaptation of CAD-CAM onlays: Influence of preparation design and impression technique.

STATEMENT OF PROBLEM: Factors that may affect the marginal adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) restorations include preparation design, impression technique, and CAD-CAM system. The influence of impression technique and preparation design on CAD-CAM partial coverage restorations has not been fully addressed. PURPOSE: The purpose of this in vitro study was to investigate the influence of direct and indirect digital scanning techniques and 2 preparation designs on the marginal adaptation of CAD-CAM onlays. MATERIAL AND METHODS: Two mesio-occlusal buccal onlay preparations with reduction of the mesiobuccal cusp were made: conventional preparation (CP) with a 1.2-mm modified shoulder margin and modified preparation (MP) flat cuspal reduction without shoulder. Virtual models were generated from each preparation by using a digital scanner (BlueCam; Dentsply Sirona) from the plastic teeth (direct digital scan) or from the stone dies (indirect digital scan). Onlays were designed using a CAD-CAM system (CEREC 4.0; Dentsply Sirona), and nanoceramic resin blocks (Lava Ultimate Restorative; 3M ESPE) were milled using the CEREC MCX milling machine. Marginal discrepancy was evaluated using an optical stereomicroscope at ×25 magnification in 18 locations distributed along the margins of the preparation. The data were analyzed by using 3-way ANOVA followed by the Tukey HSD test (α=.05). RESULTS: CP presented a statistically significant reduced average marginal adaptation (59 ±50 μm) than did MP (69 ±58 μm) (P CONCLUSIONS: The results showed that conventional preparation with a modified shoulder margin presented improved marginal adaptation compared with modified preparation with flat cuspal reduction. Direct and indirect digital scanning techniques produced restorations within a clinically acceptable range; however, the indirect scanning technique resulted in the fabrication of restorations with superior marginal adaptation on the buccal location

Current all-ceramic systems in dentistry: a review

This article describes the ceramic systems and processing techniques available today in dentistry. It aims to help clinicians understand the advantages and disadvantages of a myriad of ceramic materials and technique options. The microstructural components, materials\u27 properties, indications, and names of products are discussed to help clarify their use. Key topics will include ceramics, particle-filled glasses, polycrystalline ceramics, CAD/CAM, and adhesive cementation

Percepções de escolares com deficiência visual em relação ao seu processo de escolarização

A promoção da inclusão escolar de pessoas com deficiência visual demanda que os profissionais conheçam as percepções que estes alunos têm a respeito de suas limitações e possibilidades. Neste estudo, foram identificadas características e percepções de escolares com deficiência visual em relação ao seu processo de reabilitação. Foi realizado um estudo descritivo transversal com escolares de 12 anos e mais, inseridos no sistema público de um município do Estado de São Paulo. Aplicou-se questionário mediante entrevista. Obteve-se população de 26 alunos, sendo 46,2% com visão subnormal e 53,8% com cegueira, com média de idade de 17,1 anos. A repetência escolar foi declarada por 73,1%. Entre as dificuldades escolares decorrentes da cegueira, sobressaiu-se a leitura de livros didáticos e, entre as decorrentes da visão subnormal, a visualização da lousa. O nível de escolaridade mostrou-se baixo em relação à média de idade. Evidenciaram-se percepções coerentes em relação à problemática da inclusão escolar