Abstract
Aims: To determine the effect of an antioxidant agent on the tensile bond strength values of metal brackets bonded with to human enamel after bleaching. Materials and Methods: Thirty two sound human maxillary and mandibular premolars extracted for orthodontic reasons were collected. All teeth had undamaged buccal enamel, no caries and no pre-treatment with any chemicals. They were then stored in a solution of 0.1 % thymol before the experiment. Results: In the present study, we found that , tensile bond strength in group of direct bonding after bleaching was lower than other groups when compared with control group and the difference was significant at level p< 0.05 . The present investigation confirmed that waiting for a period of 7 days after bleaching is sufficient to obtain ade-quate tensile bond strength for clinical conditions. There was significant difference in tensile bond strength when the brackets that underwent direct bonding and ethanol with control group. No signifi-cant difference in tensile bond strength was observed when compared with the bracket immersed in a distilled water & with control bracket. Conclusions: In the present study we found that , tensile bond strength in group of direct bonding after bleaching were the lowest than other groups and when com-pared with the control group, the difference is significant. There was a significant difference in tensile bond strength when comparing the group that underwent direct bonding with control group.
Highlights
Tooth whitening, or tooth bleaching, is a procedure that involves the removal of stains and discoloration, as well as lighting of pigmentation within the teeth through the application of a chemical agent to oxidize the organic pigmentation in the tooth(1)
The Findings of this study showed the mean of the control group gave rise to the highest tensile strength, followed by the group that was immersed in distilled water, the ethanol group while the direct bonding showed lowest value when compared with remaining groups
Table (2) displays the comparison between control and all other groups, it can be observed that the lowest tensile bond was observed in the group that was bleached and directly bonded with brackets with significant difference, while the groups that was treated with antioxidant and the group that was immersed in distilled water had mean tensile bond higher than that of direct bonding groups, but less than the control with no significant difference with it
Summary
Tooth bleaching, is a procedure that involves the removal of stains and discoloration, as well as lighting of pigmentation within the teeth through the application of a chemical agent to oxidize the organic pigmentation in the tooth(1). Vital tooth bleaching is a safe and well–accepted procedure for the treatment of surface and intrinsic staining of teeth(3). Bleaching of discolored teeth can be performed before or after fixed orthodontic appliance treatment. Numerous studies have revealed that if an in–office or an at–home system is used prior to adhesive restorations or before application of resin bonded fixed appliances, the bonding strength to tooth structures is significantly reduced(6–10). To eliminate or reduce clinical problems related to post–bleached compromised bond strength, some techniques have been suggested, such as the removal of a superficial layer of enamel(11). The waiting period for bonding procedures after bleaching has been reported to vary from 24 hours to four weeks(14–17)
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