Friday I had the pleasure of learning from Dr. Harald Heymann, UNC School of Dentistry professor, at the Society for Color and Appearance in Dentistry meeting in Chicago. Harald spent an hour discussing techniques and scientific information on whitening, and I was taking notes furiously. Whitening is an everyday occurrence in my general practice. We are recommending these services and helping patients with both in office and tray bleaching systems, as well as the many patients who are whitening with OTC products on a regular basis.
One of the many valuable things covered was the current information regarding carbamide and hydrogen peroxide bleaching and their impact on bond strengths to enamel. This morning I went to pubmed and pulled several of the articles that were quoted and others and did a little review of the literature on this subject. The evidence supports that exposure to both carbamide peroxide and hydrogen peroxide whitening solutions in any of the formulations currently available over the counter or professionally delivered decreases bond strengths to enamel.The good news is that the reduction in bond strengths is transient. Once whitening has been stopped bond strengths return to normal following a period of seven days thanks to the buffering effect of saliva. There are also chemical agents that can be applied to the teeth to accomplish the same reversing effect.
The biggest challenge I see is not with patients that are actively undergoing whitening under our direction. In that group of patients we are aware that the enamel is being exposed to the whitening agents, and managing the planned treatment to account for both the color shifting and alteration in bond strengths following whitening. It is the patients who are actively bleaching on their own that present the challenge. How many adolescent patients who come in for sealants or placement of orthodontic brackets are utilizing OTC whitening products as recently as the evening prior to their appointment? How many of your adult new patients are coming in for composite restorations who are doing the same thing, or have a tray system from a previous office with gel, and decide they should whiten for a few nights right before they get their new fillings?
I know one of the things I will be doing when I get back to the office is sharing this information with my team, and adding this to my list of pre-operative instructions when discussing adhesive procedures with patients.
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