May 2016
Volume 37, Issue 5

Peer-Reviewed

Try-in Pastes Versus Resin Cements: A Color Comparison

Edenize Cristina Vaz, DDS; Maysa Magalhães Vaz, DDS; Maria Beatriz Rodrigues Gonçalves de Oliveira, DDS; Alfa Emília Takano, DDS; Paula de Carvalho Cardoso, DDS, MS, PhD; Érica Miranda de Torres, DDS, MS, PhD; and Lawrence Gonzaga Lopes, DDS, MS, PhD

Abstract: This study aimed to compare the color of ceramic veneer restorations using different shades of try-in pastes and resin cements. Forty bovine teeth and 40 ceramic discs (0.6-mm thick, color ETC0) were prepared. Initially, the discs were placed over the teeth using try-in material and, subsequently, bonded with resin cements. The specimens were divided into four groups (n = 10): group I, water-soluble gel and resin cement value 0; group II, try-in paste and resin cement value 0; group III, try-in paste and resin cement value -3; group IV, try-in paste and resin cement value +3. The color was measured using a spectrophotometer to obtain the values L*, a*, and b* and calculate the color difference (ΔE*). Three values of ΔE* were calculated: ΔE1* in the trial, ΔE2* after cementation, and ΔE3* for the color difference between the trial and cementation. Kruskal-Wallis and Wilcoxon (P < .05) tests were applied to compare ΔE1* and ΔE2* and one-way ANOVA (P < .05) to compare ΔE3* among groups. No statistical differences were found among ΔE1*, ΔE2*, and ΔE3* obtained for the groups tested (P = .701, P = .704, and P = .312, respectively). Similarly, comparing ΔE1* and ΔE2* obtained for each group in pairs, no statistically significant differences were found (P = .646, P = .169, P = .508, and P = .05, for groups I, II, III, and IV, respectively). No differences were observed between try-in pastes and resin cements after cementation.

As a result of innovation and development in restorative materials, ceramic veneers are currently preferred over other types of restorations because they require only minimally invasive tooth preparation.1 Additionally, the properties of ceramic veneers, such as color stability, mechanical strength, compatibility with periodontal tissues, clinical longevity, and enamel-like appearance, make them a good choice for esthetic treatments.2 However, clinical color reproduction still poses a challenge due to color interaction with the underlying substrate, whether it is tooth structure or an esthetic restorative material.3

Ceramic veneers generally have a thickness from 0.3 mm to 0.7 mm4; however, literature data are not conclusive about the influence of this parameter on the final color of ceramic restorations.3,5 Therefore, a question has been raised: Would different shades of resin cement under various thicknesses of different ceramic veneer materials cause perceptible color differences in ceramic restorations?5

Current adhesive systems and resin cements allow effective interaction between ceramic veneer and tooth structure.6,7 These materials come in several colors, which vary in hue, chroma, and value.7 Resin cements exhibit favorable fracture load, good longevity, and satisfactory clinical performance.8 The resin cements specifically used for luting ceramic veneers are activated by visible light. These cements present color stability and longer working time compared with chemically cured and dual-cured materials.2

For clinical evaluation, the ceramic material is placed over the substrate prior to cementation; this can be carried out with water, glycerin gel, or try-in pastes.9 The try-in pastes, which accompany resin cements, allow dentists to predict the final esthetic result.8 Nevertheless, the color agreement between the try-in paste and the resin cement under ceramic restorations is critical, especially when using extremely thin and translucent ceramic materials.8,10,11

The color selection process is complex due to the different characteristics of the color components, lighting type (natural or artificial), subjectivity of the viewer’s perception and experience, scales, dental shape, gloss, surface texture, translucency, gingival color, adjacent teeth, and tooth position in the arch.6,12 To reduce this problem, a spectrophotometer can be used for color evaluation. This device makes color measurements based on three coordinates, namely L*, a*, and b* (CIE L*a*b* system), allowing the degree of perceptible color to be evaluated using numerical values.8,13,14

Objective

The objective of this investigation was to compare the final color of ceramic veneer restorations using different shades of either try-in pastes or resin cements. The null hypothesis was that the ceramic colors obtained with the try-in materials and resin cements tested would present no differences.

Method
Teeth and Discs Preparation

In this in vitro study, 40 bovine teeth were used. The teeth were stored in 0.05% thymol solution. Prior to use, they were kept in deionized water for 24 hours to remove thymol. Crowns were utilized, and the enamel surface was ground flat with wet 180-grit silicon carbide abrasive paper, model 3M-211Q (3M, Brazil, www.3m.com.br), on a polishing machine, model DP-10 (Panambra Struers, Brazil, www.struers.com) (Figure 1).

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