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Influência do tempo de armazenamento na estabilidade dimensional do alginato: estudo laboratorial
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Objetivo: avaliar a influência do tipo de alginato e do tempo de armazenamento na estabilidade dimensional de impressões. Materiais e Métodos: foram realizadas 80 impressões a um modelo de acrílico com dois diferentes alginatos de vazagem tardia. Metade das impressões foram realizadas com Orthoprint e a outra metade com Hydrogum 5. Para cada alginato foram constituídos quatro grupos, dependendo do tempo de armazenamento, sendo as impressões vazadas a gesso imediatamente após a sua obtenção e às 24, 48 e 120 horas (n=10). Cada impressão foi submetida a protocolo de desinfeção e armazenada em sacos específicos até ao momento de vazagem a gesso. Foram realizadas medições no sentido ântero-posterior e transversal. Cada medição foi efetuada três vezes e a média dessas três medições foi utilizada como referência de cada espécime. Foi calculada a diferença entre cada espécime e o modelo de acrílico. Sempre que possível, os valores obtidos foram tratados com teste ANOVA duas vias, seguidas de testes post-hoc segundo Tukey. Em alternativa, foram utilizados testes segundo Kruskal-Wallis e Mann-Whitney com correção de Bonferroni. A significância estatística foi fixada em 95% (alfa=0,05). Resultados: tanto na medição ântero-posterior como na medição transversal não existem diferenças estatisticamente significativas entre os dois alginatos em estudo (p>0,05). Por outro lado, nas medições consideradas, a estabilidade dimensional foi influenciada de forma estatisticamente significativa pelo tempo de armazenamento (p<0,05). Não foram verificadas interações estatisticamente significativas entre os dois fatores em estudo (p>0,05). Conclusões: enquanto a estabilidade dimensional dos alginatos estudados não é afetada pelo tipo de alginato, o tempo de armazenamento da impressão antes da vazagem a gesso influencia a estabilidade do alginato.
Objectives: to study the effect of storage time on dimensional stability of two extended-pour alginates. Materials and Methods: in this in-vitro study, a total of 80 alginate impressions were taken from a standard acrylic model. Half of the impressions were made using Orthoprint and the other half using Hydrogum 5. Each impression was submitted to a disinfection protocol. The impressions that were not poured immediately, were stored in a sealed plastic bag for 24, 48 and 120 hours. The impressions were poured with type III dental stone. Cross-arch and anteroposterior measurements were made with a digital caliper on the casts obtained. Each measurement was performed three times and the mean of these three measurement was used as reference of each specimen. The difference between each specimen and the standard acrylic model was calculated. Whenever possible, data were treated with statistic test ANOVA two-way, followed by Tukey’s post-hoc test. Alternatively, Kruskal-Wallis and Mann-Withney tests with Bonferroni corrections were used. Statistical significance was set at 95% (alpha=0,05). Results: both in anteroposterior and cross-arch measurements there were no statistically significant differences between the two alginate materials under study (p>0,05). However, in the measurements considered, the dimensional stability of alginate impressions was influenced, in a statistically significant way, by the storage time (p<0,05). There was no statistically significant interaction between the two factors under study (p>0,05). Conclusions: dimensional stability of the alginates studied is not affects by the type of alginate. On the other hand, the storage time of the impression before casting influences the dimensional stability of the impressions obtained.
Objectives: to study the effect of storage time on dimensional stability of two extended-pour alginates. Materials and Methods: in this in-vitro study, a total of 80 alginate impressions were taken from a standard acrylic model. Half of the impressions were made using Orthoprint and the other half using Hydrogum 5. Each impression was submitted to a disinfection protocol. The impressions that were not poured immediately, were stored in a sealed plastic bag for 24, 48 and 120 hours. The impressions were poured with type III dental stone. Cross-arch and anteroposterior measurements were made with a digital caliper on the casts obtained. Each measurement was performed three times and the mean of these three measurement was used as reference of each specimen. The difference between each specimen and the standard acrylic model was calculated. Whenever possible, data were treated with statistic test ANOVA two-way, followed by Tukey’s post-hoc test. Alternatively, Kruskal-Wallis and Mann-Withney tests with Bonferroni corrections were used. Statistical significance was set at 95% (alpha=0,05). Results: both in anteroposterior and cross-arch measurements there were no statistically significant differences between the two alginate materials under study (p>0,05). However, in the measurements considered, the dimensional stability of alginate impressions was influenced, in a statistically significant way, by the storage time (p<0,05). There was no statistically significant interaction between the two factors under study (p>0,05). Conclusions: dimensional stability of the alginates studied is not affects by the type of alginate. On the other hand, the storage time of the impression before casting influences the dimensional stability of the impressions obtained.
Descrição
Tese de mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2017
Palavras-chave
Saúde oral Alginato Teses de mestrado - 2017