Change of shade by light polymerization in a resin cement polymerized beneath a ceramic restoration

Colour stability and opacity of resin cements and flowable composites for ceramic veneer luting after accelerated ageing

“…2,3 Colour changes of the luting agent can become visible, affecting the aesthetic appearance of the final restoration. 4 The currently available resin cements specifically used for luting ceramic veneers are usually activated by visible light. The main advantages of these cements are their colour stability and longer working time, compared to chemically and dual-cured resin cements.…”

An investigation into the effect of try-in pastes, uncured and cured resin cements on the overall color of ceramic veneer restorations: An in vitro study

“…_ 6 ) T D $ F I G ] 43 Moreover, resin cements samples became darker after light polymerisation beneath 1 and 2 mm thick porcelain veneers and therefore, influenced the color of the final veneer [ 1 0 2 _ T D $ D I F F ] restoration. 44 Color changes of resin cements on polymerisation were not clinically significant as some these color change values were just above the perceptibility threshold with Rely-X neutral, Calibra dark and Nexus-3 dark and white shades changed color by less than the perceptible threshold of 1 DE*. Therefore, in a clinical context the guidance of the try-in paste is limited and the color of the final restoration is more accurately guided by the color of the uncured resin.…”

“…However, it has been demonstrated that a significant change in color may occur during polymerisation of the resin cement and that this should be considered during shade selection and [ 3 8 _ T D $ D I F F ] manufacture. 28 While visual shade-matching is most practical in a clinical environment, in a laboratory the use of spectrophotometric techniques allows for reliable and reproducible measurements of the color of [ 3 9 _ T D $ D I F F ] porcelain. 29,30 Spectrophotometers measure CIE-LAB values [ 4 0 _ T D $ D I F F ] 31 to give a numeric value of 3D color (E*) which can then be used to assess color change (DE[ 4 1 _ T D $ D I F F ] *).…”

Avaliação de cor em compósitos com o espectrofotômetro Easyshade

“…Também é importante entender se essas diferenças são perceptíveis e, nesse caso, se são clinicamente relevantes 9 . 12,13 . Esse sistema consiste em parâmetros nos quais o L* se refere à coordenada de luminosidade, que vai do branco (100) ao preto (0) e as variáveis de cromaticidade a* e b* são as coordenadas relativas à cor nos eixos vermelho-verde e amarelo--azul, respectivamente.…”

“…O equipamento também faz a medição de cor na função "Restauração", em que pode-se checar extraoralmente a cor de uma restauração e verificar se corresponde à cor escolhida previamente. Conforme os resultados de um estudo anterior 19 , podem ocorrer divergências quando o aparelho é usado em restaurações, entanto, se tem utilizado clinicamente e em pesquisas científicas, contrariando as indicações do fabricante 12,13,20 . Nessa perspectiva, torna-se necessária a realização de trabalhos para esclarecer a viabilidade e a confiabilidade da leitura de cor de resinas compostas com o VITA Easyshade ® Compact.…”