Effect of adhesive types on enamel discolouration around orthodontic brackets.

BACKGROUND: Unsightly colour changes may occur in the enamel around bonded orthodontic brackets. AIM: To determine the enamel colour changes around orthodontic brackets bonded with different adhesives. METHODS: One hundred extracted upper first premolars were divided into five equal groups. Fiducial holes were drilled in the buccal and palatal surfaces of the teeth and metal orthodontic brackets were bonded to the buccal surfaces with different combinations of adhesives and primers. The teeth were immersed in a tea-coffee solution for one week. The brackets were then debonded and the teeth polished. The colour of the enamel surface was measured around each fiducial hole before bonding (baseline), after debonding and after polishing. The colour differences (deltaE) were compared using one-way ANOVA and the paired t-test. RESULTS: There were no significant differences between the five adhesive groups in baseline-debonding deltaE and baseline-polishing deltaE, but statistically significant differences were found between the baseline-debonding deltaE on the buccal and palatal surfaces and the baseline-debonding deltaE versus baseline-polishing deltaE on the buccal surfaces. Although statistically significant, the colour changes would not be visible to many observers. Approximately 75 per cent of the staining was attributed to the enamel components. CONCLUSIONS: The type of adhesive and the methods of application had no effect on enamel colour change. Most of the colour change was attributed to uptake of stain by the components of the enamel, not the resin tags.

Double-blind study on materials testing with applied kinesiology.

Applied Kinesiology (AK) is a scientifically unproven method used in complementary medicine to recognize the (in)tolerance of dental materials. Test-retest reliability of AK was examined. The working hypothesis was the assumption that the reliability of AK would not exceed random chance. Two dentists qualified in AK examined 112 volunteers to determine individual (in)tolerance toward two dental composite materials. After the first examination, 31 subjects were excluded from further testing. At the end of the open test phase, 34 of 81 participants had been classified as "tolerant", and seven as "intolerant" to both materials. The remaining 40 individuals showed a combination of either tolerant (to material I)/intolerant (to material II), or the reverse (n = 20 each). Retrieval rate was tested under blind conditions. In 14 cases, the results of the open and blinded tests matched, whereas in 26 cases they did not (95% confidence interval, 21%-52%; p = 0.98). This outcome confirmed our working hypothesis.

Biocompatibilidade de materiais endodônticos. Resposta do tecido subcutâneo de cobaias à resina poliuretana derivada do óleo de mamona - Parte 2 / Biocompatibility of endodontic materials subcutaneous tissue response of guinea-pig to polyurethane resin derived from castor bean oil - Part 2

A poliuretana derivada do óleo de mamona apresenta uma fórmula molecular que tem mostrado compatibilidade com os tecidos vivos. O propósito deste trabalho foi o de comparar esse polímero (Poliol) com quatro materais - AH26, Dentinol, Kerr Sealer, e Sealapex - segundo as normas da FDI e ADA/ANSI, com a finalidade da sua utilizaçäo como cimento de obturaçäo de canal. Todos os materiais foram manipulados de acordo com as instruçöes dos fabricantes. O método utilizado foi o de implante subcutâneo de tubos de Teflon em cobaias. (FDI, 1980; ADA/ANSI, 1982) Foram utilizadas 45 cobaias (+800gr cada), que receberam quatro implantes dorsais com o mesmo material (12 por período). A parede externa do tubo serviu como controle da técnica. Após 30, 60, e 90 dias, os animais foram mortos e os espécimes processados para exame histológico de rotina...