Novo design de laminados oclusais ultrafinos CAD/CAM de resina composta e cerâmica para o tratamento de erosão severa

Abstract

O objetivo deste estudo foi avaliar a influência de materiais para processamento CAD/CAM (cerâmica vs. resina composta) na resistência à fadiga de laminados oclusais ultrafinos (0,6 mm) e finos (1,2 mm). Setenta molares extraídos receberam um preparo não retentivo padronizado (simulando erosão oclusal avançada) onde o esmalte oclusal foi removido e a dentina exposta foi imediatamente selada (Optibond FL). Por intermédio do sistema Cerec 3 (Sirona), 40 dentes foram restaurados com laminados oclusais de 0,6 mm de espessura e 30 deles com 1,2 mm de espessura. As cerâmicas reforçadas Empress CAD (grupos ECAD06 e ECAD12) e e.max CAD (grupos EMAX06 e EMAX12) e a resina composta Paradigm MZ100 (grupos MZ06 e MZ12) foram utilizadas na usinagem das restaurações (n=10). Uma resina composta experimental (grupo XR06) também foi incluída somente para a espessura 0,6 mm (n=10). A superfície interna das restaurações foi condicionada com ácido fluorídrico e silanizada (cerâmicas) ou microjateada com óxido de alumínio e silanizada (resinas compostas). Os preparos foram microjateados e condicionados com ácido fosfórico antes da inserção das restaurações. Todas as restaurações foram cimentadas adesivamente pré-aquecendo-se a resina composta Filtek Z100. Esforços cíclicos isométricos foram aplicados à frequência de 5 Hz, iniciando com uma carga de 200 N (5000x) seguido por estágios de 400, 600, 800, 1000, 1200 e 1400 N a um máximo de 30.000 ciclos cada. O número de ciclos quando ocorreu a falha inicial (primeiras trincas) foi registrado. Os espécimes foram ciclados até a ocorrência de uma falha catastrófica (perda de 20 fragmento da restauração) ou até um máximo de 185.000 ciclos. Os grupos foram comparados pelo método Kaplan-Meier (P=0,008 para os grupos/0,6 mm e P=0,016 para os grupos/1,2 mm; corrigido por Bonferroni). Os resultados revelaram que: 1) para os grupos 0,6 mm Empress CAD e e.max apresentaram a falha inicial a uma carga média de 500 N e 800 N, respectivamente e nenhum dos espécimes sobreviveu aos 185.000 ciclos (sobrevivência de 0%); com os materiais MZ100 and XR a taxa de sobrevivência foi de 60% e 100%, respectivamente; 2) para os grupos 1,2 mm Empress CAD falharam a uma carga média de 900 N, e nenhum dos espécimes sobreviveu a todos os 185.000 ciclos de carga (sobrevivência de 0%); com e.max CAD e MZ100 a taxa de sobrevivência foi de 30% e 100%, respectivamente. As duas resinas compostas MZ100 and XR aumentaram a resistência à fadiga dos laminados oclusais ultrafinos (P<0,001) quando comparados ao Empress CAD and e.max. A resina composta MZ100 aumentou a resistência à fadiga dos laminados oclusais finos (P<0,002) quando comparada aos materiais Empress CAD e e.max CAD.

The aim of this study was to assess the influence of CAD/CAM restorative material (ceramic vs. composite resin) on the fatigue resistance of ultra-thin (0.6 mm-thick) and thin (1.2 mm-thick) occlusal veneers. Seventy extracted molars received a standardized nonretentive tooth preparation (simulating advanced occlusal erosion) including removal of occlusal enamel and immediate dentin sealing (Optibond FL). Using Cerec 3 (Sirona) forty teeth were restored with a 0.6 mm-thick occlusal veneer and 30 teeth with a 1.2 mm-thick. The reinforced ceramics Empress CAD (groups ECAD06 and ECAD12) and e.max CAD (groups EMAX06 and EMAX12) and the composite resins Paradigm MZ100 (groups MZ06 and MZ12) were used to mill the restorations (n=10). An experimental block (group XR06) was also included only for 0.6 mm-thick occlusal veneers (n=10). The intaglio surfaces were HF-etched and silanated (reinforced ceramics) or airborne-particle abraded and silanated (composite resins). Preparations were airborne-particle abraded and etched before restoration insertion. All restorations were adhesively luted with preheated Filtek Z100. Cyclic isometric chewing was applied at 5 Hz, starting with a load of 200 N (5,000X), followed by stages of 400, 600, 800, 1000, 1200 and 1,400 N at a maximum of 30,000 cycles each. The number of cycles at initial failure (first cracks) was recorded. Samples were loaded until catastrophic failure (lost restoration fragment) or to a maximum of 185,000 cycles. Groups were compared using the Kaplan-Meier survival curves (P=.008 for 0.6 mm-groups and P=0.016 for 1.2 mm-groups, Bonferroni-corrected). The results revealed that: 1) for 0.6 mm-thick occlusal veneers Empress CAD and e.max initially failed at an average load of 500 N and 800 N, respectively and none of them withstood all 185,000 load cycles (survival 0%); with MZ100 and XR the survival rate was 60% and 100%, respectively. 2) for 1.2 mmthick occlusal veneers Empress CAD failed at an average load of 900 N, and none of them withstood all 185,000 load cycles (survival 0%); with e.max CAD and MZ100 survival rate was 30% and 100%, respectively. Both composite resins MZ100 and XR increased the fatigue resistance of ultra-thin occlusal veneers (P<.001) when compared to Empress CAD and e.max. Composite resin MZ100 increased the fatigue resistance of thin occlusal veneers (P<.002) when compared to Empress CAD and e.max CAD. The aim of this study was to assess the influence of CAD/CAM restorative material (ceramic vs. composite resin) on the fatigue resistance of ultra-thin (0.6 mm-thick) and thin (1.2 mm-thick) occlusal veneers. Seventy extracted molars received a standardized nonretentive tooth preparation (simulating advanced occlusal erosion) including removal of occlusal enamel and immediate dentin sealing (Optibond FL). Using Cerec 3 (Sirona) forty teeth were restored with a 0.6 mm-thick occlusal veneer and 30 teeth with a 1.2 mm-thick. The reinforced ceramics Empress CAD (groups ECAD06 and ECAD12) and e.max CAD (groups EMAX06 and EMAX12) and the composite resins Paradigm MZ100 (groups MZ06 and MZ12) were used to mill the restorations (n=10). An experimental block (group XR06) was also included only for 0.6 mm-thick occlusal veneers (n=10). The intaglio surfaces were HF-etched and silanated (reinforced ceramics) or airborne-particle abraded and silanated (composite resins). Preparations were airborne-particle abraded and etched before restoration insertion. All restorations were adhesively luted with preheated Filtek Z100. Cyclic isometric chewing was applied at 5 Hz, starting with a load of 200 N (5,000X), followed by stages of 400, 600, 800, 1000, 1200 and 1,400 N at a maximum of 30,000 cycles each. The number of cycles at initial failure (first cracks) was recorded. Samples were loaded until catastrophic failure (lost restoration fragment) or to a maximum of 185,000 cycles. Groups were compared using the Kaplan-Meier survival curves (P=.008 for 0.6 mm-groups and P=0.016 for 1.2 mm-groups, Bonferroni-corrected). The results revealed that: 1) for 0.6 mm-thick occlusal veneers Empress CAD and e.max initially failed at an average load of 500 N and 800 N, respectively and none of them withstood all 185,000 load cycles (survival 0%); with MZ100 and XR the survival rate was 60% and 100%, respectively. 2) for 1.2 mmthick occlusal veneers Empress CAD failed at an average load of 900 N, and none of them withstood all 185,000 load cycles (survival 0%); with e.max CAD and MZ100 survival rate was 30% and 100%, respectively. Both composite resins MZ100 and XR increased the fatigue resistance of ultra-thin occlusal veneers (P<.001) when compared to Empress CAD and e.max. Composite resin MZ100 increased the fatigue resistance of thin occlusal veneers (P<.002) when compared to Empress CAD and e.max CAD.