Influência da espessura da cerâmica no comportamento biomecânico, sobrevivência e na translucidez de coroas monolíticas
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Data
2020-01-24
Autores
Dal Piva, Amanda Maria de Oliveira [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Apesar do aumento do uso de coroas monolíticas, seu desempenho, em diferentes aspectos, ainda não foi determinado. Inicialmente, este projeto investigou o comportamento biomecânico de diferentes coroas monolíticas convencionais sobre dentes e a distribuição de tensões na camada de cimento (Artigo 1). Como objetivo principal, este estudo avaliou o efeito do princípio do mínimo preparo dental no comportamento biomecânico, confiabilidade e translucidez de coroas monolíticas posteriores em cerâmica. No entanto, para definir o substrato a ser utilizado para receber as coroas usinadas, uma análise complementar foi desenvolvida para observar o comportamento da restauração sobre diferentes substratos através da análise por elementos finitos (Artigo 2). E para o Artigo 3, cento e vinte e seis coroas foram fabricadas e divididas (n = 21 / gr) de acordo com o material (zircônia de alta translucidez -YZHT, silicato de lítio reforçado com zircônia - ZLS e cerâmica híbrida -HC) e espessura (0,5 – subgrupo .5 ou 1 mm – subgrupo 1). A concentração de tensão de tração foi calculada pelo método dos elementos finitos, as coroas adesivamente cimentadas foram fadigadas pelo teste step-stress para calcular a confiabilidade de missões a 600 e 900 N a 100.000 ciclos; e, a translucidez foi analisada em 10 discos de cada material e espessura. Maior concentração de tensão de tração foi observada em coroas mais finas e com módulo de elasticidade mais alto. As coroas YZHT foram suspensas quando a fadiga atingiu a carga de 1.500N, sendo utilizado Weibull 1-parâmetro para analisar os dados. A confiabilidade foi afetada apenas pela espessura em 900 N. ZLS.5 apresentou sobrevida semelhante à HC.5, que foi semelhante aos grupos que apresentaram 100% de sobrevivência. YZHT mostrou a maior resistência característica e dispersão de dados. ZLS1 (22,3 ± 1,4) apresentou maior translucidez que HC1 (19,2 ± 0,6) e YZHT1 (12,0 ± 2,9), enquanto ZLS.5 e HC.5 foram semelhantes (26,5 ± 2,3, 26,7 ± 2,2) e superiores a YZHT.5 (12,7 ± 1,2). O HC.5 combinou alta confiabilidade e translucidez com baixa concentração de tensão, produzindo melhor desempenho da coroa e preservação dos dentes.
Despite the increased use of monolithic crowns, their performance in different aspects has not yet been determined. Initially, this project investigated the biomechanical behavior of different conventional monolithic crowns on teeth and the stress distribution in the cement layer (Article 1). As main purpose, this study evaluated the effect of minimal dental preparation principle on the biomechanical behavior, reliability and translucency of posterior monolithic ceramic crowns. However, to define the substrate to be used to receive the machined crowns, a complementary analysis was developed to observe the restoration behavior on different substrates using the finite element analysis (Article 2). And for Article 3, one-hundred twenty six crowns were divided (n=21/gr) according to the material (High translucent zirconia - YZHT, Zirconia reinforced lithium silicate - ZLS and Hybrid ceramic - HC) and thickness (0.5 or 1 mm). Tensile stress concentration was calculated using the finite element method, the crowns were adhesivelly cemented and step stress fatigued to calculate reliability for missions at 600 and 900 N at 100,000 cycles; and, the translucency was analyzed in 10 discs of each material and thickness. Higher stress concentration was found in thinner crowns and those with higher elastic modulus. YZHT crowns were suspended when fatigue reached 1,500N load, thus 1-parameter Weibull was used to analyse the data. Reliability was only affected by thickness at 900 N. ZLS.5 showed similar survival to HC.5, which was similar to the groups that presented 100% survival. YZHT showed the highest strength and data scattering. ZLS1 (22.3 ± 1.4) presented higher translucency than HC1 (19.2 ± 0.6) and YZHT1 (12.0 ± 2.9), whereas ZLS.5 and HC.5 were similar to each other (26.5 ± 2.3, 26.7 ± 2.2) and superior to YZHT.5 (12.7 ± 1.2). HC.5 combined high reliability and translucency with low stress concentration, yielding better crown performance and tooth preservation.
Despite the increased use of monolithic crowns, their performance in different aspects has not yet been determined. Initially, this project investigated the biomechanical behavior of different conventional monolithic crowns on teeth and the stress distribution in the cement layer (Article 1). As main purpose, this study evaluated the effect of minimal dental preparation principle on the biomechanical behavior, reliability and translucency of posterior monolithic ceramic crowns. However, to define the substrate to be used to receive the machined crowns, a complementary analysis was developed to observe the restoration behavior on different substrates using the finite element analysis (Article 2). And for Article 3, one-hundred twenty six crowns were divided (n=21/gr) according to the material (High translucent zirconia - YZHT, Zirconia reinforced lithium silicate - ZLS and Hybrid ceramic - HC) and thickness (0.5 or 1 mm). Tensile stress concentration was calculated using the finite element method, the crowns were adhesivelly cemented and step stress fatigued to calculate reliability for missions at 600 and 900 N at 100,000 cycles; and, the translucency was analyzed in 10 discs of each material and thickness. Higher stress concentration was found in thinner crowns and those with higher elastic modulus. YZHT crowns were suspended when fatigue reached 1,500N load, thus 1-parameter Weibull was used to analyse the data. Reliability was only affected by thickness at 900 N. ZLS.5 showed similar survival to HC.5, which was similar to the groups that presented 100% survival. YZHT showed the highest strength and data scattering. ZLS1 (22.3 ± 1.4) presented higher translucency than HC1 (19.2 ± 0.6) and YZHT1 (12.0 ± 2.9), whereas ZLS.5 and HC.5 were similar to each other (26.5 ± 2.3, 26.7 ± 2.2) and superior to YZHT.5 (12.7 ± 1.2). HC.5 combined high reliability and translucency with low stress concentration, yielding better crown performance and tooth preservation.
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Palavras-chave
Fadiga, Coroas monolíticas, Materiais dentários, Preparo dental mínimo, Fatigue, Monolithic crowns, Dental Materials, Tooth minimal preparation