Influência dos diferentes fluxos de trabalho CAD/CAM na precisão e qualidade dos contatos proximais e oclusais em coroas de dissilicato de lítio / Influence of different CAD/CAM workflows on the accuracy and quality of proximal and occlusal contacts in lithium disilicate crowns

Esse estudo in vitro objetivou avaliar o efeito do fluxo de trabalho digital utilizando diferentes sistemas CAD/CAM (Chairside e InLab) na precisão de coroas de dissilicato de lítio quanto à reprodutibilidade e qualidade dos contatos oclusais e proximais. Foram confeccionadas coroas de dissilicato de lítio (n=50), em que mensurou-se três fluxos de trabalho CAD/CAM Chairside ­ CEREC Bluecam (n=10), CEREC Apollo Di ­ CAI (n=10) e 3Shape TRIOS ­ (n=10) ­ e dois fluxos de trabalho CAD/CAM inlab ­ CEREC InEos X5 ­ (n=10) e 3Shape D900 (n=10). Para a avaliação dos contatos, coroas foram projetadas virtualmente; imagens dos contatos oclusais e proximais oferecidas pelo software dos sistemas; capturadas e pareadas com as imagens reais dessas coroas após a fresagem e fixação com elastômero intencionando simular a cimentação e checagem dos contatos por meio de carbono. As imagens foram inseridas em um software de forma randomizada e avaliadas por três avaliadores, calibrados e blindados usando de questionários com scores e escala visual analógica (EVA). Utilizou-se, ainda, o Teste Kruskal-Wallis e o Pós-teste de Mann Whitney com penalização de Bonferroni (significância estatística de 0,0083) para a comparação dos contatos nas proximais, simulando clinicamente (real) versus os contatos virtualmente apresentados pelos sistemas, havendo diferenças estatisticamente significantes (p<0,001). Os sitemas Bluecam (M= 6.48) e ApolloDi (M=6.15) apresentaram valores médios melhores em relação ao Ineos (M=3.65) e 3Shape D900 (M=3.41). O TRIOS (M=4.60) obteve avaliação similar a ambos. No que concerne à comparação dos contatos oclusais das coroas simulando clinicamente (real) versus os contatos virtualmente apresentados pelos sistemas, usou-se ANOVA e Pós-teste de Tahame. Houve diferença estatisticamente significativa (p= 0.002) entre o sistema TRIOS (M=7.99) e os sistemas Ineos (M=6.78) e 3Shape D900 (M=6.94), assim como entre os diferentes sistemas chairside e Inlab (p<0,001) na avaliação dos contatos oclusais após checagem por meio de carbono, simulando uma situação clínica usando o teste ANOVA e Pós-teste de Tukey (Bluecam M= 7.89; ApolloDi M= 7.27; TRIOS M= 7.41; 3Shape D900 M= 6.90 e Ineos M= 4.09). Resultado semelhante foi observado na avaliação qualitativa desses contatos oclusais, no qual foi aplicado o teste de Qui-Quadrado na categoria Excelete/Bom para os sistemas Bluecam (93,3%), ApolloDi (73,3%), TRIOS (86.7%) e 3Shape D900 (70 %), e na categoria Deficiente o Ineos (93,3%). O teste de Qui-Quadrado também foi empregue na análise da qualidade clínica dos contatos proximais por meio do uso do fio dental. Assim, 50% das coroas apresentaram deficiência do contato, com ausência de ponto de contato. Apenas o sistema TRIOS apresentou 75% na categoria Excelente/Bom. Dentro das limitações do estudo, conclui-se que os sistemas Chairside mostraram melhores resultados quando comparados aos sitemas InLab na reprodução dos pontos de contatos oclusais e proximais identificados no programa virtual com os contatos reais após fresagem e fixação das coroas, simulando uma situação clinica; e melhor acurácia na qualidade dos contatos oclusais e proximais comparados aos sitemas InLab, que apesar de apresentarem resultados inferiores também foram favoráveis (AU).

The purpose of this in vitro study was to evaluate the effect of the digital workflow using different CAD / CAM systems (Chairside and InLab) in lithium disilicate crowns, regarding the reproducibility and the quality of occlusal and proximal contacts. Lithium disilicate crowns were produced (n=50) and divided into the following groups: -Three chairside CAD / CAM workflows: CEREC Bluecam (n = 10), CEREC Apollo Di CAI (n = 10), 3Shape TRIOS (n = 10) and two InLab CAD / CAM workflows: CEREC InEos X5 (n = 10) and 3Shape D900 (n = 10). Images of occlusal and proximal contacts calculated from virtual models were compared to images of real contacts, identified through carbon, in milled crowns that were fixed with elastomer to simulate cementation. The images were inserted into a software in a randomized way and evaluated by 3 blind and calibrated evaluators through questionnaires and a visual analogue scale (VAS). The Kruskal-Wallis Test and the Mann Whitney Post-test with Bonferroni corrections (statistical significance of 0.0083) were used to compare the proximal contacts of the clinically simulated crowns and the proximal contacts of the virtual crowns. Statistically significant differences (p <0.001) were found, in which the Bluecam (M = 6.48) and ApolloDi (M = 6.15) systems obtained better mean values compared to Ineos (M = 3.65) and 3Shape D900 (M = 3.41). TRIOS (M = 4.60) obtained similar results to both groups. The occlusal contacts were compared trough ANOVA and Tahame Post-test. There was a statistically significant difference (p = 0.002) between the TRIOS (M = 7.99) system and the Ineos (M = 6.78) and 3Shape D900 (M = 6.94) systems. There was also a statistically significant difference between the different chairside and InLab systems (p <0.001) in the occlusal contacts evaluation with carbon, using the ANOVA test and Tukey's post-test (Bluecam M = 7.89; ApolloDi M = 7.27; TRIOS M = 7.41; 3Shape D900 M = 6.90 and Ineos M = 4.09). A similar result was observed in the qualitative assessment of these occlusal contacts, using the Chi-Square test, in the category Excellent / Good for Bluecam systems (93.3%), ApolloDi (73.3%), TRIOS (86.7%) and 3Shape D900 (70%) and in the Deficient category, Ineos (93.3%). The Chi-Square test was also used to analyse the clinical quality of proximal contacts, using dental floss and 50% of the crowns had contact deficiency, with no contact point. Only the TRIOS system presented 75% of their crowns categorized as Excellent / Good. Within the limitations of the study, it was concluded that the Chairside systems showed better results when compared to the InLab systems in reproducing the virtual occlusal and proximal contact points in the real contacts after milling and fixing the crowns, simulating a clinical situation. Chairside systems also showed better accuracy in the quality of occlusal and proximal contacts compared to InLab systems, which, despite presenting inferior results, were also satisfactory (AU).

In vitro evaluation of marginal fit of zirconia-reinforced lithium silicate laminate veneers at two thicknesses using different CAD/CAM systems / Avaliação in vitro do ajuste marginal de folheados laminados de silicato de lítio reforçados com zircônia em duas espessuras usando diferentes sistemas CAD / CAM

Objective: The purpose of this in vitro study was to evaluate the marginal fit of laminate veneers made of zirconia-reinforced lithium silicate with two thicknesses using different CAD/CAM systems. Material and methods: 42 Laminate veneers milled from zirconia-reinforced lithium silicate were divided into three main groups according to milling machine used into: group X5, laminate veneers fabricated by inLab MCX5 milling machine; group CM, laminate veneers fabricated by Ceramill motion 2 milling machine; and group XL, laminate veneers fabricated by inLab MCXL milling machine. Each group was divided into two subgroups according to veneer thickness into: subgroup I, 0.5 mm thickness laminate veneers and subgroup II, 0.3 mm thickness laminate veneers. The marginal fit was measured using stereomicroscope. The results were tabulated and statistically analyzed using two-way ANOVA test followed by Tukey's post hoc test. Comparisons of main and simple effects were done utilizing Bonferroni correction. The significance level was set at (p ≤0.05) for all tests. Results: The mean( ± SD) highest marginal discrepancy was recorded in subgroup CMII at 85.45 ± 1.82 µm while the least mean marginal discrepancy was recorded in subgroup X5I (71.24 ± 2.64 µm). Conclusion: Both thicknesses(0.5 mm thickness and 0.3 mm thickness) and all tested CAD/CAM systems produced zirconia-reinforced lithium silicate laminate veneers with clinically acceptable marginal gaps; however, the closed CAD/CAM systems produced veneers with superior marginal fit than open systems at 0.3 mm thickness. The CAD/CAM system with the 5-axis milling machine produced the best marginal fit with 0.5 mm thickness. (AU)

Objetivo: O objetivo deste estudo in vitro foi avaliar a adaptação marginal de facetas laminadas de silicato de lítio reforçado com zircônia com duas espessuras, utilizando diferentes sistemas CAD / CAM. Material e métodos: 42 facetas laminadas fresadas a partir desilicato de lítio reforçado com zircônia foram divididos em três grupos principais de acordo com a fresadora usada em: grupo X5, facetas laminadas fabricados pela fresadora inLab MCX5; grupo CM, facetas laminadas fabricados por Ceramill motion 2; e grupo XL, facetas laminadas fabricados pelo inLab MCXL. Cada grupo foi dividido em dois subgrupos, de acordo com a espessura do laminado, em: subgrupo I, facetas laminadas com 0,5 mm de espessura e subgrupo II, facetas laminadas com espessura de 0,3 mm. A adaptação marginal foi medida usando estereomicroscópio. Os resultados foram tabulados e analisados estatisticamente usando o teste ANOVA de dois fatores seguido pelo teste post hoc de Tukey. Comparações dos efeitos principais e simples foram realizadas utilizando a correção de Bonferroni (P ≤ 0,05). Resultados: A maior discrepância marginal média ( ± DP) foi registrada no subgrupo CMII em 85,45 ± 1,82 µm, enquanto a menor discrepância marginal média foi registrada no subgrupo X5I 71,24 ± 2,64 µm. Conclusão: Ambas as espessuras (0,5 mm e 0,3 mm)e todos os sistemas CAD / CAM testados produziram facetas de laminado de silicato de lítio reforçadas com zircônia com lacunas clinicamente aceitáveis. No entanto, os sistemas CAD / CAM fechados produziam facetas com adaptação marginal superior aos sistemas abertos com 0,3 mm de espessura. O sistema CAD / CAM com a fresadora de 5 eixos produziu a melhor adaptação marginal com 0,5 mm de espessura (AU)

Effect of immediate dentin sealing, bonding technique, and restorative material on the bond strength of indirect restorations / Efeito do selamento imediato da dentina, técnica de união e material restaurador na resistência de união de restaurações indiretas

Objective: The objective of this study was to evaluate the effect of immediate dentin sealing, bonding technique, and restorative material on the dentin bond strength of an indirect composite (Solidex) and a resin nanoceramic CAD/CAM block (LAVA Ultimate). Material and Methods: A total of 120 periodontally extracted human molar teeth were abraded horizontally and divided into two groups according to dentin sealing procedures (delayed dentin sealing [DDS] and immediate dentin sealing [IDS]). Next, all teeth were attached to a simulated pulpal pressure mechanism. The specimens were removed from the mechanism after a week. Teeth were subdivided into three groups based on the bonding technique and the type of cement used (Acid-etching + Single Bond Universal + RelyX Ultimate, Single Bond Universal + RelyX Ultimate, RelyX Unicem). Each subgroup was further divided into 2 subgroups according to the type of restorative material used (Solidex [n = 10], Lava Ultimate CAD/ CAM restorative material [n = 10]). Sixty cylindrical samples prepared using both the restorative materials were bonded to the tooth surface according to their group's bonding procedures. All specimens were embedded in chemically cured acrylic resin for shear bond strength test. The shear bond strength (SBS) of the specimens was determined by a universal testing machine with a headspeed of 0.5 mm/min. Results: Three-way ANOVA, independent-sample t test and post hoc Tukey comparison tests (α=0.05) were performed on all data. There were significant differences between the groups. It was found that IDS process significantly increased bond strength in all groups. When dentin bond strengths of tested luting cements were compared, the highest bond strength values were recorded in groups in which the specimens were luted with RelyX Ultimate cement using etch-and-rinse technique. The lowest bond strength values were obtained from groups that used RelyX Unicem as the luting cement. Conclusion: IDS improves bond strength of indirect restorations. Moreover, bonding techniques may have critical effects on the dentin bond strength of indirect restorative materials. The cements' specific affinity levels to both restorative materials and dentin could be considered as the reason of the situation.(AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito do selamento imediato da dentina, da técnica adesiva e do material restaurador na resistência de união à dentina de um compósito indireto (Solidex) e um bloco CAD / CAM de resina nanocerâmica (LAVA Ultimate). Material e Métodos: Um total de 120 dentes molares humanos extraídos por razões periodontais foram desgastados horizontalmente e divididos em dois grupos de acordo com os procedimentos de selamento dentinário (vedação tardia da dentina [DDS] e vedação imediata da dentina [IDS]). Em seguida, todos os dentes foram conectados a um equipamento de pressão pulpar simulada. As amostras foram removidas do equipamento após uma semana. Os dentes foram subdivididos em três grupos, com base na técnica de união e no tipo de cimento utilizado (ataque ácido + Single Bond Universal + RelyX Ultimate, Single Bond Universal + RelyX Ultimate, RelyX Unicem). Cada subgrupo foi então dividido em 2 subgrupos de acordo com o tipo de material restaurador utilizado (Solidex [n = 10], material restaurador Lava Ultimate CAD / CAM [n = 10]). Sessenta amostras cilíndricas preparadas com os dois materiais restauradores foram coladas na superfície do dente de acordo com os procedimentos de adesão do grupo. Todas as amostras foram embebidas em resina acrílica quimicamente ativada para o teste de resistência ao cisalhamento. A resistência de união ao cisalhamento (SBS) das amostras foi determinada por uma máquina de teste universal com uma velocidade de 0,5 mm / min. Resultados: ANOVA de três fatores, teste t de amostra independente e testes de comparação post hoc de Tukey (α = 0,05) foram realizados em todos os dados. Houve diferenças significativas entre os grupos. Verificou-se que o processo IDS aumentou significativamente a força de união em todos os grupos. Quando as forças de união da dentina dos cimentos testados foram comparadas, os valores mais altos de força de união foram registrados nos grupos em que as amostras foram cimentadas com cimento RelyX Ultimate usando a técnica "condicione e lave". Os menores valores de resistência de união foram obtidos de grupos que usaram como cimento o RelyX Unicem. Conclusão: O IDS melhora a força de união das restaurações indiretas. Além disso, as técnicas de união podem ter efeitos críticos na resistência da união à dentina de materiais restauradores indiretos. Os níveis de afinidade específicos dos cimentos para materiais restauradores e dentina podem ser considerados o motivo da situação.(AU)

Analysis of reasons for failure of chair-side CAD/CAM ceramic restorations / 口腔疾病防治

Objective@#To investigate the failure reasons of all-ceramic restorations fabricated with chair-side CAD-CAM technology (CEREC®) and to improve the clinical survival of all-ceramic restorations. @*Methods @#All-ceramic single-tooth restorations of CEREC® in stomatology hospital of Jiangsu province between 2013 and 2016 were summarized. By clinical examination and CEREC Biogeneric surveying, the failure reasons and related restoration types were evaluated. These results were analyzed with Chi-square test and Spearman correlation analysis. @*Results@#A total of 61 cases with restoration types of 11 inlays, 38 onlays, 2 endocrowns, and 11 all-crowns, resulted in a failure rate of 5.4% in all-ceramic single-tooth restorations in 1-4 years follow-up. The reasons for failure included ceramic fracture (n=33), debonding (n=13), tooth fracture (n=15), which attributed to thin ceramic thickness (n=27), acute line angle (n=6), insufficient enamel bulk (n=3), insufficient retention type (n=10), insufficient resistance type (n=15).@*Conclusion @# The most common reason for failure in CEREC® restorations was insufficient preparation space in occlusal surface.

The Effect of Lithium Disilicate Glass-Ceramic Core Thickness on Fracture Thickness of All-ceramic Restorations.

Statement of the Problem: Fracture strength is fundamental for the long-term success and clinical service of all-ceramic restorations. Core thickness is an important factor affecting fracture strength. Purpose: The main objective of this study was to assess and compare the fracture strength of 0.4 mm and 0.7 mm core thicknesses. Materials and Methods: In this in vitro, experimental study, one brass die was prepared with classic chamfer finish line design (0.8 mm depth). An impression was made from the metal die and poured with epoxy resin. The epoxy resin die was scanned and lithium disilicate glass ceramic core was fabricated by the computer-aided design/computer-aided manufacturing (CAD/CAM) technique. IPS e.max cores with 0.4 and 0.7 mm thicknesses were fabricated using CAD/CAM technique. Ten samples were fabricated of each thickness and veneered with IPS e.max. After adhesive bonding onto the die, they were vertically loaded using a universal testing machine until fracture. The data were statistically analyzed using the Kolmogorov-Smirnov test and t-test. Results: The mean and standard deviation (SD) of fracture strength were 1754±313.47 and 1073±202.81 N, for 0.7 mm and 0.4 mm cores, respectively. The Kolmogorov-Smirnov test showed normal distribution of data; thus, t-test was applied for comparison of the two groups (p<0.001). The fracture strength of 0.7 mm core was significantly greater than that of 0.4 mm core. Conclusions: Within the limitations of this study, it was concluded that increasing the core thickness improves the fracture strength. However, the mean fracture strength values obtained for 0.4 and 0.7 mm core thicknesses were far greater than the load threshold applied in the oral cavity; thus, both thicknesses can be successfully used in the clinical setting.