Title For a Patient Seeking Orthodontic Care, Stronger Shear Bond Strength (SBS) May Be Achieved by Not Bleaching the Teeth Before Bonding Brackets
Clinical Question In an adult interested in orthodontic care, does bleaching prior to bracket placement reduce SBS when compared patients that do not undergo tooth bleaching?
Clinical Bottom Line Bleaching should be discontinued at least 14 days prior to orthodontic bracket placement if one is using a bleaching product that is greater than 35% hydrogen peroxide solution. The only current bleaching solution that has no adverse effects on SBS is RBCM (resin-based coating material). Both hydrogen peroxide and carbamide peroxide bleaching solutions show a decrease in SBS if the bonding of brackets occurs soon after bleaching as well as when the concentrations of hydrogen peroxide and carbamide peroxide are increased in the bleaching solutions.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
31629708Imani/201919 in vitro studiesMeta-Analysis
Key resultsThis study found that bleaching with hydrogen peroxide reduces the SBS when bonding to enamel. This is especially true if bonding of the orthodontic brackets occurs quickly after bleaching or if using higher than 35% hydrogen peroxide bleaching solution.
31275517de Almeida/201980 bovine teethIn vitro study
Key resultsIn groups of bovine teeth that were bleached with 35% hydrogen peroxide 1 and 7 days before bracket bonding, the SBS was below that of the control (no bleaching). However, for the group of teeth that were bleached 14 days before bracket bonding, the SBS was minimally affected and comparable to the SBS of the control group. It was determined from the researcher’s data that the SBS between the enamel and adhesive/bracket/composite interface was more effective after 14 days of no bleaching with 35% hydrogen peroxide.
21299411Scougall-Vilchis/2011150 bovine teethIn vitro study
Key resultsThis study compared different bleaching systems and their effects on SBS when bonding orthodontic brackets. Bovine teeth were assigned to different types of bleaching solutions including: none (control), 38% hydrogen peroxide, 10% carbamide peroxide, resin-based coating material (RBCM) – Beauty Coat, and RBCM – White Coat. The highest SBS besides the control was the RBCM – White Coat with the other groups being significantly lower. The evidence concluded that using RBCM bleach before bonding did not reduce the SBS, whereas the hydrogen peroxide and carbamide peroxide negatively affected the SBS.
Evidence Search PUBMED: “bleaching”, “orthodontics”, “brackets”, “bond strength”, “shear bond strength”, “SBS”
Comments on
The Evidence
The meta-analysis done by Imani et.al included in-vitro studies from multiple databases including Scopus, Pubmed and Cochrane. However, the studies done by de Almeida et. al and Scougall-Vilchis et. al were based on bovine teeth and not human clinical trials. Also, in the studies above, there was no mention of blinding done between the researchers and the bovine teeth which have been treated in different ways. While the studies focus on shear bond strength, it is important to note that the laboratory shear bond strength test is accomplished in a different force vector that typical bracket removal of orthodontic brackets. Clinically, the brackets are removed with an instrument perpendicular to the long axis of the tooth, leaving as much adhesive as possible in order to prevent removal of any enamel. It is also shown that the mean adhesive strength needed for orthodontic forces is between 5.6MPa and 7.8MPa, whereas in all studies, regardless of a pre-bonding hiatus or high percentage of bleaching solution, the shear bond strength numbers were greater than those averages.
Applicability The data above shows a decrease in SBS in orthodontic brackets placed within 14 days of bleaching or using bleaching solutions with greater than 35% concentration of hydrogen peroxide. Based on these studies, implementation of a standard hiatus between bleaching and orthodontic bracket placement would be beneficial for those patients seeking orthodontic care.
Specialty (General Dentistry) (Orthodontics)
Keywords Brackets, bleaching, bond strength, SBS, orthodontics, peroxides
ID# 3432
Date of submission 05/11/2020
E-mail shortp@livemail.uthscsa.edu
Author Paxton Short
Co-author(s) e-mail
Faculty mentor Brent Callegari
Faculty mentor e-mail callegari@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available