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Biomedical subjects

José Augusto M Miguel

Publications and source records attributed to José Augusto M Miguel.

5 recordsLinked to original sources
PubMed2006

Effect of a self-etching primer on shear bond strength of adhesive precoated brackets in vivo.

The aim of this study was to evaluate the influence of a self-etching primer (SEP) (Transbond Plus SEP, 3M Unitek, Monrovia, Calif) on shear bond strength of adhesive uncoated and precoated Victory brackets (3M Unitek). The sample group consisted of 23 patients, with four premolars each, equally divided in four different groups. Brackets were bonded in vivo by the same operator using a split-mouth random technique: group 1, 37% phosphoric acid + primer + composite + conventional Victory bracket; group 2, 37% phosphoric acid + primer + precoated Victory bracket; group 3, SEP + composite + conventional bracket; group 4, SEP + precoated bracket. After 30 days, premolars were extracted for orthodontic reasons and a Universal Instron Machine was used to apply an occlusal shear force directly to the enamel-bracket interface at a speed of 0.5 mm/min. The groups were compared using two-way analysis of variance. Mean results and standard deviation for the groups were: group 1 = 11.60 +/- 2.65 Mpa, group 2 = 9.79 +/- 2.71 Mpa, group 3 = 10.75 +/- 2.67 Mpa, and group 4 = 10.31+/- 2.70 Mpa. No difference was observed between the conventional etching and primer or SEP (P = .948). However, significant differences in bond strength were present between the uncoated and precoated brackets (P = .032). Considering the values required to withstand normal orthodontic forces (8-9 Mpa), it could be concluded that the SEP combined with adhesive precoated brackets showed adequate shear bond strength and may be suitable for clinical use.

Acid Etching, Dental↗
PubMed2006

Scanning electron microscopy evaluation of the bonding mechanism of a self-etching primer on enamel.

The aim of this study was to analyze the effect of a self-etching primer (Transbond Plus SEP, 3M Unitek, Monrovia, Calif), developed for orthodontic use, in the regularity and depth of adhesive infiltration in the enamel of human permanent teeth and to compare it with phosphoric acid using scanning electron microscopy (SEM). Thirty premolars were divided in two groups of 15 each: group 1(control)-phosphoric acid + Transbond XT Primer (3M Unitek) and group 2- Transbond Plus SEP. Transbond XT Adhesive Paste (3M Unitek) was used in both groups for bracket bonding. All products were used according to the manufacturer's instructions. Dental fragments were decalcified, and for micromorphologic observation of the adhesive penetration in enamel, the resin replicas, remnant at the base of the brackets, were covered with a thin gold layer and examined by SEM. Three calibrated examiners evaluated the photomicrographs and gave scores from 0 = without penetration to 2 = deep penetration. The Mann Whitney U-test (P < .0001) showed a statistical difference between the two groups. The results demonstrated that the SEP was more conservative and produced a smaller amount of demineralization and less penetration of adhesive in the enamel surfaces when compared with the conventional phosphoric acid system.

Acid Etching, Dental↗
PubMed2006

Evaluation of a new self-etching primer on bracket bond strength in vitro.

The purpose of this in vitro study was to evaluate the influence of a new self-etching primer (Adper Prompt L-pop; 3M ESPE, St Paul, Minn) on shear bond strength of orthodontic brackets. Forty extracted human premolars were obtained and randomly divided into two groups of 20 each: group 1 (control), phosphoric acid + Transbond XT primer (3M Unitek, Monróvia, Calif) and group 2, Adper Prompt L-pop. Transbond XT adhesive paste (3M Unitek) was used in both groups for bracket bonding. All products were used according to the manufacturer's instructions. Instron Universal Testing Machine was used to apply an occlusal shear force directly onto the enamel-bracket interface at a speed of 0.5 mm/min. The groups were compared using Student's t-test. Mean results and standard deviation for the groups were: group 1 = 16.23 MPa (4.77), group 2 = 13.56 MPa (4.31). No significant difference was observed in the bond strengths of the two groups evaluated (P = .069). However, the adhesive remnant index was significantly less when conditioning the enamel with Adper Prompt L-pop compared with phosphoric acid (P = .0003). The results suggest no difference in bond strength whether a conventional etching and primer or Adper Prompt L-pop is used. The amount of adhesive on the enamel after debonding was significantly less when using Adper Prompt than when using phosphoric acid. These results indicated that Adper Prompt is potentially adequate for orthodontic bonding needs.

Acid Etching, Dental↗
PubMed2004

Changes in dental arch measurements of young adults with normal occlusion--a longitudinal study.

This study evaluates the longitudinal changes in occlusal dimensions in young adults. The sample was composed of 27 individuals (13 male and 14 female individuals) who presented dental Class I and normal occlusion, according to the inclusion protocol. All teeth were present except for the third molars. The mean age of the subjects was 21 years and two months initially and 28 years and four months at the end of the observation period. The measurements collected in both arches were overbite, overjet, intercanine and intermolar distances, irregularity index, and perimeter. All measurements were taken from study dental casts by a calibrated operator, using a digital caliper. The paired t-test was used to evaluate the changes, using the difference between the initial and final mean measurements. Data indicated that the overbite increased 0.39 mm, the incisor irregularity increased 0.38 mm in the upper arch and 0.54 mm in the lower arch, and the arch perimeter decreased 0.67 mm in the upper arch and 0.71 mm in the lower arch (P > .05). The other measurements did not show significant changes. No sexual dimorphism was observed. It could be concluded that occlusal dimensions change throughout adult life. In the sample studied, changes were statistically significant for overbite, incisors irregularity, and arch perimeter after a mean period of seven years and two months. These changes can be observed in both sexes.

Adolescent↗