IADR Abstract Archives
Invitro analysis of shear bond strength of orthodontic brackets with self-adhesive resin cement, and its variability over the bleached enamel.
Objectives: The objective of this in vitro study was three fold: first to evaluate the shear bond strength of self-adhesive resin as an orthodontic bracket bonding agent, second to analyse its bonding potential over the bleached enamel surface, and third was to determine the appropriate time of bracket bonding after tooth bleaching was performed.
Methods: Sixty extracted human teeth of age group 13-25 years were collected and randomly assigned into three groups (n=20). In group 1orthodontic brackets (stainless steel, standard edge wise by 3M Unitec, USA ) were bonded at labial surface of extracted teeth with RelyXU 200(3M USA).Group 2 teeth were bleached with EverbriteTM in office tooth bleaching system (Dentamerica USA) and then bonded with RelyX U200 self-adhesive resin on the same day, while group 3 teeth were bleached and then immersed in normal saline for two weeks. Bracket bonding was then performed on day 15th with RelyX U200 self-adhesive resin. Mechanical de bonding was performed with the Universal testing machine at the cross head speed 1 mm / min. The stereo microscope at the magnification of eight to ten folds was used to evaluate the failure mode through adhesive remnant index (ARI). Statistical analysis was performed by SPSS version 20 and ANOVA one way.Multiple comparisons were carried out through Tukey post hoc test. Pearson Chi Square analysed the mode of bond failure.
Results: Shear bond strength for group 1 (7.716 ± 2.56MPa) and group 3 (5.087±2.46MPa) was significantly higher than the group 2 (2.86 ± 0.94MPa). there was significant difference for group1 with group 2 (p=0.000), for group1 with group 3 (p=0.001), and for group 2 with group3 (p=0.004). For ARI, Pearson Chi Square test showed the significance level (p=0.01). The predominant failure mode of self-adhesive was adhesive at the enamel–adhesive interface.
Conclusions: RelyXU200 self-adhesive resin cement can be employed as an orthodontic bonding agent. It gives significant shear bond strength and desirable site of bond failure. Application of bleaching prior to bracketing would impede the polymerization and reduce the bond strength. So it is recommended to wait for at least two weeks to perform bracket bonding over the bleached surface of tooth.
Methods: Sixty extracted human teeth of age group 13-25 years were collected and randomly assigned into three groups (n=20). In group 1orthodontic brackets (stainless steel, standard edge wise by 3M Unitec, USA ) were bonded at labial surface of extracted teeth with RelyXU 200(3M USA).Group 2 teeth were bleached with EverbriteTM in office tooth bleaching system (Dentamerica USA) and then bonded with RelyX U200 self-adhesive resin on the same day, while group 3 teeth were bleached and then immersed in normal saline for two weeks. Bracket bonding was then performed on day 15th with RelyX U200 self-adhesive resin. Mechanical de bonding was performed with the Universal testing machine at the cross head speed 1 mm / min. The stereo microscope at the magnification of eight to ten folds was used to evaluate the failure mode through adhesive remnant index (ARI). Statistical analysis was performed by SPSS version 20 and ANOVA one way.Multiple comparisons were carried out through Tukey post hoc test. Pearson Chi Square analysed the mode of bond failure.
Results: Shear bond strength for group 1 (7.716 ± 2.56MPa) and group 3 (5.087±2.46MPa) was significantly higher than the group 2 (2.86 ± 0.94MPa). there was significant difference for group1 with group 2 (p=0.000), for group1 with group 3 (p=0.001), and for group 2 with group3 (p=0.004). For ARI, Pearson Chi Square test showed the significance level (p=0.01). The predominant failure mode of self-adhesive was adhesive at the enamel–adhesive interface.
Conclusions: RelyXU200 self-adhesive resin cement can be employed as an orthodontic bonding agent. It gives significant shear bond strength and desirable site of bond failure. Application of bleaching prior to bracketing would impede the polymerization and reduce the bond strength. So it is recommended to wait for at least two weeks to perform bracket bonding over the bleached surface of tooth.
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