RESUMO
The purpose of this study was to measure the frictional forces generated between composite, ceramic, and metal brackets and selected wire alloy-size combinations with elastomeric and stainless steel ligatures in a dry environment. Four types of composite, one ceramic, one sapphire, and one metal bracket were tested with stainless steel, nickel-titanium, and beta-titanium wires. The testing was performed with two wire sizes in the 0.018-inch slot brackets and three wire sizes in the 0.022-inch slot bracket. The recently introduced composite brackets were found to offer lower frictional resistance than the ceramic and stainless steel brackets, regardless of the wire size, wire alloy, and type of ligation. The wire alloy with the least friction was stainless steel, followed by beta-titanium and nickel-titanium. Mean variability in friction, as reflected by the magnitude of the standard deviations, was 2.7 to 3 times more with the stainless steel ligation than the elastomeric ligation.
Assuntos
Estética Dentária , Braquetes Ortodônticos , Dente Pré-Molar , Cerâmica/química , Resinas Compostas/química , Ligas Dentárias/química , Análise do Estresse Dentário/estatística & dados numéricos , Fricção , Humanos , Teste de Materiais/instrumentação , Teste de Materiais/métodos , Teste de Materiais/estatística & dados numéricos , Maxila , Elastômeros de Silicone/química , Aço Inoxidável/químicaRESUMO
The purpose of this article was twofold: (1) to provide an estimate of error in the digitization of various soft tissue landmarks using a video imaging system, and (2) to evaluate the relationships of various soft tissue measurements in balanced young adult faces. A video imaging system was used to digitize frontal and lateral soft tissue landmarks on 25 male and 25 female Caucasian young adults with Class I occlusion and esthetically pleasing and balanced soft-tissue profiles. Twenty subjects were redigitized and only two measurements showed a statistically significant error. Large variabilities were found for several measurements. Males, in general, had greater soft tissue thickness, facial depth and width, and lip length than females. The measurements were found to compare favorably with previous reports. Imaging systems were seen to have the advantage of providing reliable measurements in all three dimensions without the potential hazards of ionizing radiation.
