Layering Composite Selection In Class IV Restorations: Instrumental Evaluation

Objectives: The purpose of this study was to evaluate the ability of dental students, with experience in layering technique to realize a sample-tooth combining an estabilished range of resin composites masses. Methods: A random selection of three dental students took part in the study. The sample-tooth was a standard upper central incisor in resin composite color-defined A3. Two composites (Venus Diamond ® - Heraeus Kulzer, IPS Empress Direct - Ivoclar Vivadent) based on the enamel / dentin layering concept were selected. Each student was asked to create three class IV restorations for each composite that they used for the first time these materials. We observed the learning curve for each material; the colour difference (∆E94) and the colour distributions (Lightness - ΔL*, Chroma - ΔC*, hue - Δh* from the color space CIELCh) were spectrophotometrically assessed (SpectroShadeTM) before/after restoration. This values were referred to the variables: operators, series, backgrounds and materials used. Results: • The time spent reduced along the series of reconstructions for both materials. • According to the ANOVA test at a fixed level of significance (p = 0.05): • ΔE/Operator was statistically significant p = 0.036: Operator μ∆E94 σ ∆E94 1 5,277 1,683 2 4,621 1,570 3 4,502 1,443 Table 1 • ΔE/Series was not statistically significant, p = 0.040. Series μ∆E94 σ ∆E94 1 4,408 1,714 2 4,763 1,250 3 5,229 1,701 Table 2 • ΔE/Material the correlation was statistically significant, p = 0.000. Material μ∆E94 σ ∆E94 Venus ® Diamond - Heraeus Kulzer 3,875 1,105 IPS Empress Direct - Ivoclar Vivadent 5,725 1,472 Table 3 • ΔL/Operator: the correlation was not statistically significant • ΔL/Material: the correlation was not statistically significant • ΔL/Series: the correlation was statistically significant • ΔL/Background: the correlation was statistically significant Factors p (<0,05) Operator 0,817 Series 0,029 Material 0,246 Background 0,000 Table 4 Conclusions: the material selection is highly related to the aesthetic, althougt the learning curve is relatively fast (short time and comparable aesthetic). However, there is not great uniformity in the results due to the influence of operator subjectivity in the realization of the restoration. This aspect suggest that we need to explore the confidence and aesthetic approach using composite “recipe” layering technique and dental spectrophotometer dedicated to composite evaluation.