Color changes of ceramic veneers following glazing with respect to their composition

PURPOSE: The purpose of this study was to compare the translucency and color changes of ceramic laminate veneers of different composition following glazing process. MATERIALS AND METHODS: 10 mm × 10 mm square specimens of 0.6 mm and 1.0 mm thicknesses were fabricated with IPS e.max Press (EM) and IPS e.max ZirPress (ZP) (n=10 per group). The color coordinates (CIE L* a* b*) of the specimens were recorded with a colorimeter before and after glazing. The color changes and translucency parameter (TP) were calculated. For the comparisons with the composition and thicknesses between the ‘not glazed’ and ‘glazed’ groups, statistical analyses were done through paired T-test, independent two-sample T-test, and multiple regression analysis using SPSS 18.0 (P < .05). RESULTS: The TP of 0.6 mm EM was higher than that of 0.6 mm ZP. Total color difference (ΔE*) between bare and glazed specimens of 1.0 mm EM was greater than that of 1.0 mm ZP with statistical significance. Following glazing, specimens from all groups showed statistically significant amount of decrease in L* and a*, and statistically significant increase in b*. The result of multiple regression analysis of EM and ZP showed that ΔL* improved ΔE*. CONCLUSION: Within the limitations of present study, we conclude that translucency and color of ceramic laminate veneers change significantly after glazing process, and the nature and amount of changes vary with different compositions.

Influence of thickness and incisal extension of indirect veneers on the biomechanical behavior of maxillary canine teeth

OBJECTIVES: To analyze the influence of thickness and incisal extension of indirect veneers on the stress and strain generated in maxillary canine teeth. MATERIALS AND METHODS: A 3-dimensional maxillary canine model was validated with an in vitro strain gauge and exported to computer-assisted engineering software. Materials were considered homogeneous, isotropic, and elastic. Each canine tooth was then subjected to a 0.3 and 0.8 mm reduction on the facial surface, in preparations with and without incisal covering, and restored with a lithium disilicate veneer. A 50 N load was applied at 45° to the long axis of the tooth, on the incisal third of the palatal surface of the crown. RESULTS: The results showed a mean of 218.16 µstrain of stress in the in vitro experiment, and 210.63 µstrain in finite element analysis (FEA). The stress concentration on prepared teeth was higher at the palatal root surface, with a mean value of 11.02 MPa and varying less than 3% between the preparation designs. The veneers concentrated higher stresses at the incisal third of the facial surface, with a mean of 3.88 MPa and a 40% increase in less-thick veneers. The incisal cover generated a new stress concentration area, with values over 48.18 MPa. CONCLUSIONS: The mathematical model for a maxillary canine tooth was validated using FEA. The thickness (0.3 or 0.8 mm) and the incisal covering showed no difference for the tooth structure. However, the incisal covering was harmful for the veneer, of which the greatest thickness was beneficial.

Influence of ceramic material, thickness of restoration and cement layer on stress distribution of occlusal veneers

Abstract The aim of this study was to evaluate stress distribution in an occlusal veneer according to the restorative material, restoration thickness, and cement layer thickness. A tridimensional model of a human maxillary first molar with an occlusal veneer preparation was constructed using a modeling software of finite element analysis. The model was replicated 9 times to evaluate the factors: restoration thickness (0.6, 1.2, and 1.8 mm) and cement layer thickness (100, 200, and 300 μm). Then, each model received different restorative materials (High Translucency Zirconia - [YZHT], Lithium Disilicate - [LD], Zirconia Reinforced Lithium Silicate - [ZLS], Feldspathic - [F], and Hybrid Ceramic - [HC]), totaling forty-five groups. An axial load (600 N) was applied on the occlusal face for static structural analysis. Solids were considered isotropic, homogeneous, and linearly elastic. Contacts were considered perfectly bonded. Fixation occurred in the dental root and a mechanical static structural analysis was performed. Descriptive statistical analysis and one-way ANOVA (α =10%) were performed for tensile stress peak values in the restoration and cement layer. The difference between groups was compared using the Tukey's test with 10% significance to match the percentage of the mesh convergence test. According to the results, the cement layer thickness did not influence stress distribution in the restoration (p ≥ 0.10). The thicker the restoration, the higher the tensile stress concentration in the restoration. The graphs showed higher stress concentration in the YZHT, followed by LD, F, ZLS, and HC. Also, the restorative material influenced stress concentration on the cement layer, which decreased according to the sequence HC>YZHT>ZLS>LD>F. HC stood out for causing the least stress concentration in the restoration. Cement layer thickness did not interfere in the mechanical performance of the restorations.

Solución estética a un dilema en las restauraciones indirectas con corona y carillas simultáneas: Reporte de un caso / Dental restoration with laminate veneers and ceramic crown, aesthetic solution to a routine dilemma. Case Report

El presente artículo presenta una alternativa de solución ante la necesidad de resolver el sector anterior con combinaciones de carillas y corona. Se confeccionó una infraestructura que simula a un diente natural tallado para carilla y luego la cementación de las carillas sobre dientes preparados y sobre la infraestructura adhoc.Esta es una alternativa ante la imposibilidad de coincidir estéticamente de manera adecuada una situación clínica en la cual la coincidencia estética sea un reto; el manejo del caso estuvo basado en una planificación precisa que inicia con un diseño digital personalizado, recogiendo las expectativas estéticas de la paciente y luego en una traducción a modelos encerados, para transitoriamente pre visualizar el diseño en un ensayo restaurador en boca, el cual sirvió también como guía precisa para las preparaciones dentarias de las carillas a manera de pre-provisionales, finalmente para confeccionar los provisionales y orientar el formato de las futuras cerámicas. La predictibilidad de los resultados conseguidos fue gracias a una adecuada planificación y las cualidades estéticas y mecánicas de los materiales dentales restauradores indirectos empleados en este caso.

The following article presents an alternative to resolve the esthetic zone with a combined treatment, consisting of laminate veneers and full coverage crown. A substructure that simulates natural tooth structure prepared for veneer was built, and then laminate veneers were fabricated and cemented over these adhoc substructures. The case was based in a meticulous treatment planning, which starts with custom smile design, gathering the patients´ expectations and appropriate principles in dental esthetics. The result is then rendered in a diagnostic wax up, so the final outcome can be pre-visualized in the mouth by a mock-up. This mock-up will be later on used as a precise guide for the reduction required for the veneers, and serving as pre-provisionals. Predictability of the excellent results obtained is due to an adequate planning and of course quality and good handling of the dental materials used in the present case.