In this case it is necessary to work on the pulpar cavity, by making a hole in the palatal wall of the tooth, as the whitening gel must be used in the inner part of the tooth. The clinician can decide to leave the gel positioned for about one hour, and then repeat the operation after a week, for other 3 or 4 times, or he can leave the gel inside the tooth and dismiss the patient, and then change the gel after a few days. Even in this last case, the operation needs to be repeated 3 or 4 times.
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