Shear bond strength of ceramic brackets with different base designs to feldspathic porcelains

Abstract

Objective: To test the hypothesis that the there is no difference between the shear bond strengths of different base designs of ceramic brackets bonded to glazed feldspathic porcelains. Materials and Methods: Forty glazed feldspathic porcelain specimens (15 mm in diameter and 1.5 mm in thickness) were prepared and divided into 4 groups (n = 10). Ten pieces of each group of different ceramic bracket base designs (beads, large round pits, and irregular base) and one group of stainless steel brackets (served as a control) were bonded to glazed feldspathic porcelains under a 200 gram load. Then all samples were subjected to shear bond strength evaluation with a universal testing machine at a crosshead speed of 0.2 mm/min. Data were analyzed through one-way ANOVA and Tukey's HSD test at a .05 significance level. The mode of failure after debonding was examined under a stereoscope. Results: This study revealed that the beads base design had the greatest shear bond strength (24.7 ± 1.9 MPa) and was significantly different from the large round pits base (21.3 ± 2 MPa), irregular base (19.2 ± 2.0 MPa), and metal mesh base (15.2 ± 2.4 MPa). The beads base design had 100% porcelain-adhesive failure, the large round pits had 100% bracket-adhesive failure, and the irregular base design had 70% combination failure and 30% porcelain-adhesive failure. Conclusions: The hypothesis is rejected. The various base designs of metal and ceramic brackets influence bond strength to glazed feldspathic porcelain, but all should be clinically acceptable. © 2009 by The EH Angle Education and Research Foundation, Inc.