Evaluation of the marginal and internal gaps of partially crystallized versus fully crystallized zirconia-reinforced lithium silicate CAD-CAM crowns: An in vitro comparison of the silicone replica technique, direct view, and 3-dimensional superimposition analysis.

STATEMENT OF PROBLEM: The crystallization process of lithium disilicate crowns has been reported to cause dimensional change, but whether the fit of chairside computer-aided design and computer-aided manufactured (CAD-CAM) zirconia-reinforced lithium silicate crowns is affected is unclear. PURPOSE: The purpose of this in vitro study was to evaluate with a 3-dimensional superimposition analysis technique the marginal and internal adaptation of fully crystallized versus partially crystallized zirconia-reinforced lithium silicate ceramic CAD-CAM fabricated crowns. Additionally, the silicone replica technique and direct viewing of marginal gap values were compared with the 3-dimensional superimposition analysis technique. MATERIAL AND METHODS: The marginal and internal adaptation of a fully crystallized zirconia-reinforced lithium silicate (CELTRA DUO) were compared with those of a partially crystallized zirconia-reinforced lithium silicate (VITA SUPRINITY) after crystallization. Sixteen crowns (n=8) were fabricated with a chairside CAD-CAM system. The crowns and die and crown assembly were scanned with an optical scanner for the 3-dimensional superimposition analysis. Four hundred sixty-eight measurements were made for each crown, 78 in each 2-dimensional section. Marginal discrepancy was measured by using the direct viewing technique. The internal adaptation of the shoulder area, axial space, and occlusal space was measured by using the silicone replica technique. Both gap values were compared with the 3-dimensional superimposition analysis results by using the independent t test. The 2-way ANOVA was used to detect the effect of each variable (group and site) (α=.05). RESULTS: The VITA SUPRINITY crowns showed statistically higher marginal discrepancy values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and the direct viewing method, and the lingual aspect recorded the highest marginal discrepancy mean value when compared with other aspects. The 3-dimensional superimposition analysis and the direct viewing method were statistically similar (P=.076). The VITA SUPRINTY crowns showed higher internal gap mean values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and silicone replica techniques. The occlusal space recorded the highest mean value in both groups. Assessment by 3-dimensional superimposition analysis and silicone replica techniques showed statistical difference in internal gap values (P=.04). CONCLUSIONS: CELTRA DUO showed better precision fit values than VITA SUPRINITY. Three-dimensional superimposition analysis is a reliable method of evaluating marginal and internal adaptation.

Evaluation of zirconia crowns restoring endodontically treated posterior teeth with 2 finish line designs and 2 occlusal reduction schemes: A randomized clinical trial.

STATEMENT OF PROBLEM: Preparation design has been linked to restoration survival, and the finish line geometry, such as a deep chamfer or shoulder, has been linked to marginal integrity. However, limited data are available for restoration success with the feather-edge finish line when used with monolithic zirconia crowns with different occlusal reduction schemes. PURPOSE: The purpose of this randomized clinical trial was to evaluate the clinical performance of 2 finish line designs (feather-edge and rounded shoulder) in relation to 2 occlusal designs (flat and planar) in endodontically treated teeth restored with monolithic zirconia crowns. MATERIAL AND METHODS: Sixty-six complete-coverage monolithic zirconia crowns were provided for posterior endodontically treated teeth. The participants were divided into 3 groups based on the preparation design: the control group (PS) had a planar occlusal scheme with a rounded shoulder finish line; the first intervention group (FF) had a flat occlusal scheme with a feather-edge finish line; and the second intervention group (FS) had a flat occlusal scheme with a rounded shoulder finish line. The crowns were designed with the exocad software program and milled with a 5-axis machine. After cementation, clinical performance in terms of marginal adaptation, marginal discoloration, fracture, and secondary caries was evaluated by using the modified United States Public Health Service (USPHS) criteria. The gingival index score system was used to evaluate the gingival response. The scores were recorded immediately after cementation and at 3 subsequent follow-up visits every 3 months for 1 year. The chi-square test was used in all comparisons of outcomes and follow-up durations (α=.05). RESULTS: In terms of marginal adaptations, the control group (PS) demonstrated the best marginal adaptation scores during follow-up visits, followed by intervention 2 (FS), and lastly, intervention 1 (FF), which was scored mostly with Bravo. At the third follow-up visit, the intervention 1 (FF) group reported the most gingival responses of all groups. No significant difference among the groups was found in terms of marginal discoloration, fracture, or secondary caries at any of the follow-up visits. Each group received a perfect Alfa score of 100% on all 3 follow-up assessments. CONCLUSIONS: In this 1-year randomized clinical trial, all evaluated preparation schemes and corresponding crowns were clinically successful. The clinical performance of monolithic zirconia crowns of the novel preparation design (FF) was successful in terms of marginal adaption, fracture, secondary caries, and marginal discoloration.

Evaluation of biocompatibility of veneered Bio HPP and veneered lithium disilicate crowns in anterior zone (Randomized controlled clinical trial) / Avaliação da biocompatibilidade de coroas de Bio HPP e coroas de dissilicato de lítio na região anterior (ensaio clínico controlado randomizado)

Objective: Evaluation of the biocompatibility of Bio-High Performance Polymer (Bio HPP) crowns veneered with Visio-Ling versus e.max crowns veneered with e.max veneering system. Material and Methods: 42 full-coverage crowns were fabricated for maxillary anterior teeth. A swap was obtained using a sterile paper cone to determine bacterial count and type. Pocket depth (PD) was determined using a William Periodontal probe. Measurements were repeated after 3, 6, 9 and 12 months respectively. Patients were randomly divided into: Group A fabricated from IPS e.max crowns and Group B fabricated from Bio HPP crowns. The preparations were standardized with an equi-gingival, finish line. Fisher's test was used to compare between the two groups. The significance level was set at P ≤ 0.05. Statistical analysis was performed with Windows, Version 23.0. (IBM SPSS Statistics) Armonk, NY: IBM Corp. Results: Bio HPP and e.max showed no statistically significant difference in bleeding on probing and PD except after 9and 12 months; Bio HPP showed statistically significantly higher PD than e.max (P-value = 0.027, Effect size = 0.245) and (P-value = 0.011, Effect size = 0.310), respectively. Fisher's test showed there was no statistically significant difference between total bacterial counts and the type of the two materials. Conclusion: Both e.max and Bio HPP crowns revealed successful biological behavior. No significant difference between the materials regarding the bacterial count and type as well as the pocket depth, however after 9 and 12 months, Bio HPP showed a higher significant difference PD than e.max. (AU)

Objetivo: Avaliação da biocompatibilidade de coroas de Polímero Bio-High Performance (Bio HPP) estratificadas com Visio-Ling versus coroas e.max estratificadas com sistema de estratificação e.max. Material e Métodos: 42 coroas totais foram confeccionadas para dentes anteriores superiores. Uma amostra foi obtida usando um cone de papel estéril para determinar a contagem e o tipo de bactérias. A profundidade de bolsa (PD) foi determinada usando uma sonda periodontal de William. As medições foram repetidas após 3, 6, 9 e 12 meses, respectivamente. Os pacientes foram divididos aleatoriamente em: Grupo A fabricado com coroas IPS e.max e Grupo B fabricado com coroas Bio HPP. As preparações foram padronizadas com uma linha de término no nível da gengiva marginal. O teste de Fisher foi usado para comparação entre os dois grupos. O nível de significância foi estabelecido em P ≤ 0,05. A análise estatística foi realizada com Windows, versão 23.0. (IBM SPSS Statistics) Armonk, NY: IBM Corp. Resultados: Bio HPP e e.max não mostraram nenhuma diferença estatisticamente significativa no sangramento à sondagem e PD, exceto após 9 e 12 meses; Bio HPP mostrou PD estatisticamente significativa maior do que e.max (valor P = 0,027, tamanho do efeito = 0,245) e (valor P = 0,011, tamanho do efeito = 0,310), respectivamente. O teste de Fisher mostrou que não houve diferença estatisticamente significativa entre as contagens bacterianas totais e o tipo dos dois materiais. Conclusão: As coroas e.max e Bio HPP revelaram comportamento biológico bem-sucedidos. Não houve diferença significativa entre os materiais em relação à contagem e tipo de bactérias, bem como à profundidade da bolsa, no entanto, após 9 e 12 meses, o Bio HPP apresentou uma diferença significativamente mais elevada de PD do que e.max. (AU)