EFFECT OF OVER THE COUNTER WHITENING ON THE SHEAR BOND STRENGTH OF ORTHODONTIC BRACKETS: AN IN-VITRO STUDY

Introduction: The purpose of this study was to determine the effect of two over-the-counter enamel bleaching products on the shear bond strength of orthodontic brackets bonded to human premolar teeth with composite resin. Objectives: To assess: 1) The effects of over-the-counter white strip enamel bleaching and 2-Step whitening toothpaste application on the shear bond strength of orthodontic brackets 2) The effects of a 7 day post-bleaching latent period on the shear bond strength of orthodontic brackets 3) The amount of bleaching that occurs and its correlation to in-vitro shear bond strength of orthodontic brackets, and 4) The differences in amount of adhesive remaining on the enamel of the unbleached and bleached groups after debdonding. Methods: Two protocols were used to test 60 human premolars. Teeth were randomly divided into two groups, I and II (n=30 per group) and then further divided into 4 subgroups A, B, C, D (n=15 per group). In the over-the-counter white strip bleaching group (n= 30), Crest® 3D WHITE™ LUXE Professional Effects Whitestrips (Proctor & Gamble, Greensboro, NC) which contains 6.5% hydrogen peroxide, was applied to the teeth daily for 14 days for 30 minutes each day. Teeth in the over-the-counter whitening dentifrice group (n=30) were treated with Crest® 3D WHITE™ BRILLIANCE 2-Step Toothpaste (Proctor & Gamble, Greensboro, NC) which contains Sodium Fluoride (Step 1) and 3% hydrogen peroxide gel (Step 2) that was brushed onto the teeth daily for 14 days for 10 seconds per tooth. After bleaching, subgroups A and C were stored in artificial saliva at 37 Co for 7 days before bonding. Subgoups B and D were stored in saliva at 37o C for 24 hours before bonding. All groups were bonded by one investigator and debonded on the same day using shear forces by another investigator. The Kruskal-Wallis test for nonparametric means was used to determine whether significant differences existed between the subgroups and an unbleached control group (n= 15). Spectrophotometric color measurements were recorded pre and post-bleaching and adhesive remnant index findings were recorded after debonding. Results: The mean ± SD shear bond strength for the control group was 9.59 ± 3.32 MPa. Means for the white strip bleaching groups were 10.35 ± 3.6 MPa and 11.69 ± 4.33 MPa for the 7-day and 24-hour delayed bonding periods, respectively. Means for the whitening dentifrice groups were 11.01 ± 4.31 MPa and 10.83 ± 3.79 MPa for the 7-day and 24-hour delayed bonding periods, respectively. The mean spectrophotometric color change (∆E) for the control group was 4.67 ± 2.55. Means for the white strip bleaching groups were ∆E = 12.43 ± 3.81 and 11.54 ± 3.28 for the 7-day and 24-hour delayed bonding periods, respectively. Means for the whitening dentifrice groups were ∆E = 4.77 ± 2.39 and 7.41 ± 3.54 for the 7-day and 24-hour delayed bonding periods, respectively. The Kruskal-Wallis test demonstrates there are no statistically significant differences among the groups (p=0.650). The Pearson Correlation Coefficient analysis indicates there are no statistically significant correlations between color change and shear bond strength among the groups (p = 0.448). The Pearson’s Chi-squared value indicates that there are no statistically significant differences among the groups in respect to adhesive remaining on enamel (p = 0.731).

Grantor dc:publisher

State University of New York at Buffalo

Year dc:date.issued

2018

Author dc:creator

• Hohlen, Brian

Contributors dc:contributor

• Al-Jewair, Thikriat
• Orthodontics

• dentistry

Statement dc:rights

• Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.
• Copyright retained by author.

Language dc:language

eng

Handle dc:identifier

http://hdl.handle.net/10477/78028

OAI record oai:identifier

https://ubir.buffalo.edu/oai/request?verb=GetRecord&metadataPrefix=qdc&identifier=oai%3Aubir.buffalo.edu%3A10477%2F78028