Welding Metallurgy of

https://cyberleninka.org/article/n/247243.pdf

Current status of zirconia restoration.

The classification of malocclusion

Aspects of silane coupling agents and surface conditioning in dentistry: An overview

Zirconias, the strongest of the dental ceramics, are increasingly being fabricated in monolithic form for a range of clinical applications. Y-TZP (yttria-stabilized tetragonal zirconia polycrystal) is the most widely used variant. However, current Y-TZP ceramics on the market lack the aesthetics of competitive glass-ceramics and are therefore somewhat restricted in the anterior region. This article reviews the progressive development of currently available and next-generation zirconias, representing a concerted drive toward greater translucency while preserving adequate strength and toughness. Limitations of efforts directed toward this end are examined, such as reducing the content of light-scattering alumina sintering aid or incorporating a component of optically isotropic cubic phase into the tetragonal structure. The latest fabrication routes based on refined starting powders and dopants, with innovative sintering protocols and associated surface treatments, are described. The need to understand the several, often complex, mechanisms of long-term failure in relation to routine laboratory test data is presented as a vital step in bridging the gaps among material scientist, dental manufacturer, and clinical provider.

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Novel Zirconia Materials in Dentistry

This study evaluates the marginal adaptation of ceramic copings (In-Ceram, Vita) front of two finish lines and internal surface treatment (Rocatec, ESPE). For this, two master steel dies were milled with all-ceramic crowns preparation, one with a round shoulder (RS) margin design, and the other with a deep chamfer (DC). Twenty copings were made, and the marginal discrepancy was evaluated in measuring microscope, obtaining an initial measure. Each group was divided in two others, which received two kinds of silica sandblasting: (1) in all inner crown surface - DCt and RSt - and (2) in the inner crown surface, but preserving the cervical edge - DCa and RSa. The discrepancies were measured again and the data submitted to the statistical analysis. Marginal discrepancy values of 42,37±18,78µm were observed for group DC and 33,35±20,08µm for group RS in the initial measures, without significant statistical differences among them. The initial and final gap values were compared to each one of the experimental groups, being observed statistical differences in DCa and DCt. Statistical differences was not observed among the post-sandblasting values. It was concluded that both cervical endings present similar marginal adaptations between them when not submitted to any treatment type. When accomplished the surface treatment, negative influence was observed in the marginal adaptation of some groups, if compared the initial and final values, in spite of differences among the last ones were not been observed.

Evaluation of the marginal adaptation of ceramic copings in function of the cervical endings and treatment of the internal surfaces* Avaliação da adaptação marginal de copings cerâmicos em função do término cervical e tratamento das superfícies internas

A obtencao de um esquema oclusal balanceado e um dos fatores fundamentais para o adequado funcionamento biomecânico das proteses totais muco-suportadas. O resente trabalho tem como objetivo apresentar uma revisao da literatura sobre as alteracoes que podem ocorrer no plano oclusal destas proteses por ocasiao do processo laboratorial de inclusao e polimerizacao, apos a obtencao de uma oclusao balanceada durante a montagem dos dentes artificiais sobre os planos de orientacao.

Alterações do plano oclusal durante o processamento laboratorial de próteses totais: revisão da literatura

O objetivo deste estudo foi avaliar o efeito da ciclagem termica sobre a resistencia adesiva entre a superficie cerâmica do In-Ceram (Vita Zahnfabrik, Bad Sackingen, Alemanha) e o cimento resinoso (Panavia F, Kuraray CO, Japao). Foram fabricados nove blocos cerâmicos com dimensoes de 5x6x6mm. Uma das faces com 5x6mm de cada bloco cerâmico foi condicionada com uma cobertura triboquimica de silica (Sistema Rocatec, ESPE - Seefeld - Alemanha) e em seguida cimentada com Panavia F a outro bloco identico de resina composta (Clearfil AP-X, Kuraray CO - Japao). Os nove grupos formados por cerâmica, cimento e resina composta foram cortados em 60 corpos-de-prova com dimensoes de 10x1x1mm e area adesiva que apresentava 1mm2± 0,1mm2. Os corpos-de-prova foram divididos em 3 grupos (n=20): G1 - armazenagem durante 14 dias em agua destilada a 37oC; G2 - 6000 ciclos termicos (5oC - 55oC, 30s em cada temperatura); G3 - 12000 ciclos termicos (5oC - 55oC, 30s em cada temperatura). Apos os condicionamento termicos, os corpos-de-prova foram fixados com adesivo de cianoacrilato ao dispositivo de microtracao e testados em uma maquina de ensaio universal (EMIC - DL-1000, Equipamentos e Sistemas Ltda., dos de Sao Jose Pinhais - o PR, Brasil) com velocidade constante de 0,5mm/ min. Os dados foram submetidos aos metodos estatisticos de ANOVA e Tukey . Os resultados indicaram que os valores medios de tensao de ruptura (MPa) de G1 (14.97±4.68) nao diferiram estatisticamente (p <5%) de G2 (12.27±4.72), porem houve diferenca significante entre G1 e G3 (9.89±4.16). Foi possivel concluir que a termociclagem reduziu os valores de resistencia adesiva significativamente quando os corpos-de-prova foram submetidos a 12000 ciclos.

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Avaliação da resistência adesiva entre uma cerâmica aluminizada e um cimento resinoso submetidos à ciclagem térmica

Estudo da alteração dimensional em silicones para moldagem polimerizados por reação de condensação

The present study was a prospective, controlled, randomized, clinical short-term trial aiming to evaluate the clinical performance of adhesively luted, lithium disilicate and feldspathic glass-ceramics onlays over a period up to 2 years. A total of 11 patients (7 female, 4 male; age range: 18-60 years, mean age: 39 years) were selected for this study. Each patient received a maximum of two restorations per group in a split-mouth-design. LD: Eleven onlays, performed with lithium disilicate-based ceramic (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein), and FP: Eleven onlays, performed with feldspathic ceramic (Vita Mark II, Vita Zanhfabrik, Bad Sackingen). Recalls were performed at 2 weeks (baseline = R1), 1 year (R2) and 2 years (R3) after the cementation by three calibrated blinded independent investigators using mirrors, magnifying eyeglasses, probes and bitewing radiographs. The postoperative sensitivity, secondary caries, marginal integrity, marginal discoloration, color match, surface roughness, tooth integrity, and restoration integrity were evaluated. The Friedman test was used to determine if there was a statistically significant difference in time-to-time comparison of the parameters in the ceramics restorations. A total of 95.4% of the restorations were clinically acceptable at the 2-year recall, without a difference for any evaluation parameter for both ceramic materials. Based on the 2-year data, the CAD-CAM onlays manufactured with feldspathic and lithium-disilicate based ceramics showed similar clinical performance.

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Marco Antonio Bottino

Papers

Evaluation of the marginal adaptation of ceramic copings in function of the cervical endings and treatment of the internal surfaces* Avaliação da adaptação marginal de copings cerâmicos em função do término cervical e tratamento das superfícies internas

Alterações do plano oclusal durante o processamento laboratorial de próteses totais: revisão da literatura

Avaliação da resistência adesiva entre uma cerâmica aluminizada e um cimento resinoso submetidos à ciclagem térmica

Estudo da alteração dimensional em silicones para moldagem polimerizados por reação de condensação

Feldspathic and Lithium Disilicate Onlays with a 2-Year Follow-Up: Split-Mouth Randomized Clinical Trial