Method: Resin blocks with 4mm of thickness, formed by 3 disks of resin corresponding to the vestibular enamel, dentin and palatal enamel were made. These blocks were divided into 2 groups conforming to the compound resin used for its making: group A (n=30), resin type Vit-l-escence (Ultradent); and group B (n=30), resin type 4 Seasons (Ivoclar Vivadent). Each group was subdivided into 05 subgroups (n=6), conforming to the reproduction or not of the DEJ: subgroup 1, without reproduction of DEJ; subgroup 2, reproduction of vestibular DEJ (V) with DE Connector (Ultradent); subgroup 3, reproduction of DEJ V and Palatine (P) with DE Connector; subgroup 4, reproduction of DEJ V with Single Bond (3M); and subgroup 5, reproduction of DEJ V and P with Single Bond. The blocks were analyzed in the spectrophotometer for evaluation of the reflection, brightness (coordinate L*) and fluorescence. The balances were submitted to the statistical test of variance analysis, theory of Tukey and Kruskal Wallis.
Result: The reflection values and L* increased when the DE Connector was applied, however without a statistically significant difference between subgroups A2 and A3; and B2 and B3. The fluorescence was not influenced by the application of the DE Connector.
Conclusion: The reproduction of dentin-enamel junction, through the DE Connector, between the resins for the enamel and dentin, is sufficient to increase the diffusion of internal light in a restoration with composite resin, since its use modifies the optical properties of the restoration.