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Efeito do tempo adicional de presa na estabilidade dimensional dos alginatos: estudo laboratorial
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Objetivo: Avaliar o efeito do aumento do tempo de permanência intraoral após o tempo presa recomendado pelo fabricante, na estabilidade dimensional de alginatos extended-pour. Materiais e Métodos: Foram realizadas 120 impressões a um modelo de acrílico com dois diferentes alginatos extended-pour. Foram realizadas 60 impressões para cada alginato, estas foram divididas dependendo do tempo de presa: tempo de presa recomendado pelo fabricante, 1, 2 e 3 minutos adicionais de permanência intraoral após tempo de presa recomendado pelo fabricante (n=15). Cada impressão foi submetida a protocolo de desinfeção e armazenada em sacos específicos até à vazagem a gesso. A vazagem foi realizada após 24 horas do fim da desinfeção. Foram realizadas uma medição transversal, entre os dois primeiros molares, e uma sagital, desde a linha média até distal do dente 17. Foi calculada a diferença entre cada espécime e o modelo de acrílico. Foi rejeitada a hipótese de distribuição normal nas comparações entre alginatos, logo recorreu-se ao teste não-paramétrico de Mann-Whitney U. Como não foram verificadas condições de homocedasticidade, foi realizado o teste não paramétrico de Kruskal-Wallis para comparação das categorias de Tempo de Presa. A significância estatística foi fixada em 95% (alfa=0,05). Resultados: Foi observado que não existiram diferenças significativas entre os dois alginatos quer na medição intermolar superior quer na medição sagital superior (p>0,05). Por outro lado, nas medições consideradas, a estabilidade dimensional foi influenciada de forma estatisticamente significativa pelo tempo de presa adicional (p<0,05). Conclusão: Enquanto que a estabilidade dimensional dos alginatos estudados não foi afetada pelo tipo de alginato, o aumento do tempo de permanência intraoral após o tempo de presa recomendado pelo fabricante influencia a estabilidade dimensional do alginato.
Objectives: To evaluate the effect of increasing the dwell time of the impression intraorally after the setting time recommended by manufacturer on the dimensional stability of extended-pour alginates. Materials and Methods: In this in-vitro study, a total of 120 alginate impressions were taken from a standard acrylic model. Half of the impressions were made using Orthoprint and the other half using Hydrogum 5. 60 impressions were made for each alginate, these were divided depending the setting time: setting time recommended by the manufacture, 1, 2 and 3 additional minutes of intraoral dwell time on manufacturer´s recommended setting time (n=15). Each impression was submitted to a disinfection protocol. The impressions were poured after 24 hours of the end of the disinfection. One measurement was performed transversely, between the first two molars, and one sagittal, from the midline to the distal of the teeth 17. Each measurement was made with a digital caliper on the casts obtained. The difference between each specimen and the standard acrylic model was calculated. The normal distribution hypothesis was rejected for alginate comparisons, so the non-parametric Mann-Whitney U test was used. As no homoscedasticity conditions were observed, the non-parametric Kruskal-Wallis test for comparison of the categories of setting time. Statistical significance was set at 95 % (alpha=0, 05). Results: No significant differences between the two alginates in either the upper intermolar measurement or the upper sagittal measurement (p>0,05). On the other hand, in the measurements considered, the dimensional stability was influenced in a statistically significant way by the setting time (p<0,05). Conclusions: While the dimensional stability of the alginates studied wasn´t affected by the type of alginate, the additional setting time influenced the dimensional stability of the alginate.
Objectives: To evaluate the effect of increasing the dwell time of the impression intraorally after the setting time recommended by manufacturer on the dimensional stability of extended-pour alginates. Materials and Methods: In this in-vitro study, a total of 120 alginate impressions were taken from a standard acrylic model. Half of the impressions were made using Orthoprint and the other half using Hydrogum 5. 60 impressions were made for each alginate, these were divided depending the setting time: setting time recommended by the manufacture, 1, 2 and 3 additional minutes of intraoral dwell time on manufacturer´s recommended setting time (n=15). Each impression was submitted to a disinfection protocol. The impressions were poured after 24 hours of the end of the disinfection. One measurement was performed transversely, between the first two molars, and one sagittal, from the midline to the distal of the teeth 17. Each measurement was made with a digital caliper on the casts obtained. The difference between each specimen and the standard acrylic model was calculated. The normal distribution hypothesis was rejected for alginate comparisons, so the non-parametric Mann-Whitney U test was used. As no homoscedasticity conditions were observed, the non-parametric Kruskal-Wallis test for comparison of the categories of setting time. Statistical significance was set at 95 % (alpha=0, 05). Results: No significant differences between the two alginates in either the upper intermolar measurement or the upper sagittal measurement (p>0,05). On the other hand, in the measurements considered, the dimensional stability was influenced in a statistically significant way by the setting time (p<0,05). Conclusions: While the dimensional stability of the alginates studied wasn´t affected by the type of alginate, the additional setting time influenced the dimensional stability of the alginate.
Descrição
Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2018
Palavras-chave
Saúde oral Alginato Teses de mestrado - 2018