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Influência da técnica de acabamento na estabilidade cromática dos bis-acrílicos
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Objetivo: Avaliar o efeito do tipo de polimento e do tempo de exposição a um corante na estabilidade cromática de duas resinas bis-acrílicas. Métodos: Foram preparados sessenta discos em resina bis-acrílica. Metade dos discos foram fabricados com Protemp 4 e a outra metade com Structur 3. As faces dos discos foram limpas com álcool e foram constituídos doze grupos experimentais (n=5) com base na utilização de diferentes métodos de polimento (sem tratamento adicional; escova de pelo de cabra; disco de grão grosso Sof-Lex seguido de escova de pelo de cabra; sequência de discos Sof-Lex; disco de grão grosso Sof-Lex seguido de aplicação de resina Fortify; disco de grão grosso Sof-Lex seguido de aplicação de Z-Prime Plus). Sessenta minutos após o polimento foi realizada a medição de cor inicial e os espécimes foram imersos em solução de café. Após 24 horas e 7 dias de imersão, foram realizadas novas medições dos parâmetros de cor. Para o registo da cor foram utilizados os parâmetros do sistema CIE L*a*b* e a diferença cromática foi calculada de acordo com a fórmula ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. Os dados obtidos foram analisados com testes estatísticos não paramétricos de acordo com os métodos Kruskal-Wallis, Mann-Whitney e Wilcoxon (alfa=0,05). Resultados: Os valores da ΔE variaram entre 4,9 e 11,7 (24 horas) e 13,3 e 21,4 (7 dias). O aumento do tempo de imersão do bis-acrílico na solução de café conduziu a um aumento da ΔE (p<0,001). Às 24 horas, não se encontraram diferenças entre os materiais (p=0,941). Ao fim de 7 dias, o Protemp 4 mostrou valores da ΔE (p=0,032) inferiores aos obtidos com a Structur 3. Com exceção do Protemp 4 com 7 dias de imersão, a ΔE foi influenciada pelo método de polimento (p<0,05). Conclusão: Todos os espécimes apresentaram valores de ΔE considerados clinicamente inaceitáveis.
Aim: To study the effect of several polishing techniques and time exposure to a staining agent on the colour stability of two bis-acrylic resins. Methods: Sixty cylindrical specimens of bis-acrylic were prepared, thirty with Protemp 4 and thirty with Strutur 3. Both sides of specimens were cleaned with alcohol and twelve groups were created (n=5) according to the surface treatment used (without any other treatment, goat hair brushes, Sof-Lex coarser grit disc followed by goat hair brushes, Sof-Lex sequence, Sof-Lex coarser grit disc with Fortify, Sof-Lex coarser grit disc with Z-Prime Plus). Sixty minutes after polishing, the baseline colour values were measured, and all the specimens were immersed in the staining solution (coffee). After 24 hours and 7 days additional measurements were taken. Colour changes were calculated according to the CIE L*a*b* colour scale, by the formula: ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. All data were statistically analysed by non-parametric tests according to Kruskal-Wallis, Mann-Whitney and Wilcoxon methods (alpha=0.05). Results: ΔE mean values ranged between 4.9 and 11.7 after 24 hours of immersion and between 13.3 and 21.4 after 7 days. Increasing the immersion time in the staining solution led to an increase of ΔE values (p<0,001). After 24 hours of immersion, there were no statistical differences among materials (p=0.941). After 7 days of immersion, Protemp 4 obtained lower ΔE (p=0.032) than Structur 3. The ΔE was influenced by the polishing technique, except for Protemp 4 after 7 days of immersion (p<0.05). Conclusion: All specimens presented values for ΔE that were considered clinically inacceptable.
Aim: To study the effect of several polishing techniques and time exposure to a staining agent on the colour stability of two bis-acrylic resins. Methods: Sixty cylindrical specimens of bis-acrylic were prepared, thirty with Protemp 4 and thirty with Strutur 3. Both sides of specimens were cleaned with alcohol and twelve groups were created (n=5) according to the surface treatment used (without any other treatment, goat hair brushes, Sof-Lex coarser grit disc followed by goat hair brushes, Sof-Lex sequence, Sof-Lex coarser grit disc with Fortify, Sof-Lex coarser grit disc with Z-Prime Plus). Sixty minutes after polishing, the baseline colour values were measured, and all the specimens were immersed in the staining solution (coffee). After 24 hours and 7 days additional measurements were taken. Colour changes were calculated according to the CIE L*a*b* colour scale, by the formula: ΔE*=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2. All data were statistically analysed by non-parametric tests according to Kruskal-Wallis, Mann-Whitney and Wilcoxon methods (alpha=0.05). Results: ΔE mean values ranged between 4.9 and 11.7 after 24 hours of immersion and between 13.3 and 21.4 after 7 days. Increasing the immersion time in the staining solution led to an increase of ΔE values (p<0,001). After 24 hours of immersion, there were no statistical differences among materials (p=0.941). After 7 days of immersion, Protemp 4 obtained lower ΔE (p=0.032) than Structur 3. The ΔE was influenced by the polishing technique, except for Protemp 4 after 7 days of immersion (p<0.05). Conclusion: All specimens presented values for ΔE that were considered clinically inacceptable.
Descrição
Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2014
Palavras-chave
Acrílicos - tratamento dentário Teses de mestrado - 2014