Another factor is if the patient has teeth that are sensitive to hot or cold liquids. The bleaching material may not be tolerated under these conditions. The dentist can offer whitening in a lower concentration if sensitivity is an issue.
A patient can get professional bleaching from a dentist or from over the counter products. Although the ingredients are similar, the concentration is higher and therefore more effective from the dentist. In addition, a dentist will provide custom trays, which allows the whitening material to be in closer contact with the teeth.
The dentist will present two methods; one is a tray made from impressions of the patient’s teeth. The patient wears the trays that have bleach placed in by the patient daily. In a week, the dentist evaluates the effect of the whitening.
The other method is a significantly higher concentration of bleach where a patient has the procedure performed at one sitting. A special lamp is used to activate the bleaching material.
My opinion is what I would do for myself. Therefore, I used the take home trays, which I consider safer and more controlled. I did not want such a high concentration of whitening (bleaching) material applied to me. The results will be similar and if a patient has available time, then the trays are what I would suggest.