Influência da espessura do filme de cimento na resistência adesiva de pinos de fibra de vidro cimentados em condutos radiculares de dentes humanos

• Autor(a) principal: Prado, Natália Araújo Silva
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14143
• topic: Dental dowels; Resin cements; Root canal preparation; Fluorescent dyes; Shear strength; Pinos de retenção dentária; Cimentos de resina; Preparo de canal radicular; Corantes fluorescentes; Resistência ao cisalhamento; Técnica para retentor intra-radicular; Pinos dentários; Canal radicular - Tratamento; Corantes; CNPQ::CIENCIAS DA SAUDE::ODONTOLOGIA

The present study has the purpose of evaluating the influence of the cement film thickness on the bond strength of glass fiber posts in different portions of the root canal (cervical, medium, and apical), cemented with self-adhesive resin cement, with and without the addition of Rhodamine B, by means of the push-out test. Forty roots were included in epoxy resin, underwent endodontic treatment, and were filled with gutta-percha and endodontic cement without eugenol. After seven days, the canals were de-obstructed and randomly divided into four groups (n=10), according to the WhitePost DC (FGM) fiber glass post system s burs: (G1) bur #2; (G2) bur # 3; (G3) bur #4; (G4) bur #2. The preparation was made at a 10 mm depth. The posts were cemented with RelyX U100 (3M ESPE) self-adhesive resin cement, and only in groups G1, G2, and G3 a small amount of powdered Rhodamine B was used as a stain in the cement. After one week, each root was sliced in a cutting machine, resulting in six slices 1 ± 0,1 mm thick. Before the push-out test, a stereomicroscope was used to obtain digital images of both sides of each slice, in order to determine the radius of the posts, as well as the thickness of the cement film. After the mechanical test, new images were obtained, to determine the failure mode. In order to determine the cement thickness, a macro routine was developed in the software KS 400. The data were analyzed statistically through two-way ANOVA (influence of the bur diameter and influence of the thirds), and Kruskal-Wallis (influence of the cement film thickness). Duncan test was used for multiple comparisons. All tests were run with α=0,05. There were significant differences between the groups regarding the bur diameter (p<0,0001), with G2 (14,62 ± 5,15 MPa) > G1 (10,04 ± 5,13 MPa) > G3 (7,68 ± 6,14 MPa). The canal portion had significant influence on the bond strength, and the highest values were obtained at the apical third (p = 0,0001). The cement film thicknesses were statistically different in all groups. The highest cement thickness values were obtained in G3 (248,78 μm), followed by G2 (185,91 μm), and G1 (110,16 μm), the latter being statistically similar to G4 (119,99 μm). G1 (10,04 ± 5,13 MPa) and G4 (8,89 + 5,18 MPa) showed statistically similar results, which indicates that the presence of Rhodamine B did not significantly influence the bond strength. The predominant type of failure for G1 was mixed, for G2 was adhesion between post and cement, and for G3 and G4 was adhesion between cement and dentin. The bur diameter significantly influenced the results for shear bond strength for the push-out test, as well as the cement film thickness. The slight increase in the cement thickness allowed an increase in the values of shear bond strength in comparison with very thin or very thick cement films.