Is tooth whitening with 35% carbamide peroxide ok?

Possibly: The higher the percentage of peroxide, the more likelyhood your teeth will become sensitive.

Yes, but: That is strong stuff and your teeth will get sensitive. Whitening is most effective with weaker concentrations and longer duration of use. I would not keep that strength on my teeth for more than 30 mins. Tops.

In short, maybe: That is a very strong concentration and I do not recommend keeping that on ones teeth for more than 20-30 minutes. Extreme sensitivity could develop.

Yes: Yes, but this is a high concentration, so don't use it longer that the dentist told you. If you use it longer than prescribed, you can develop sensitive teeth, which can be temporary. Follow the instructions your dentist gave you.

Of course: It is safe and FDA approved. 35% Carbamide Peroxide gel is a very good whitener with no problems if used by a dentist. Most cosmetic dentists prefer to use 35 % Carbamide Peroxide gel for better and predictable whitening results.

Yes, but strong: This is. A high concentration and needs to be used carefully and for a very short time. Follow your dentist's instructions very carefully. Possible side effects are sensitive teeth and burning of the gums tissues.

Yes: Yes; the Concentration of 35% is strong and you will need to follow the instructions given by your dentist. You will probably wear your bleaching trays for two 30min sessions twice daily following brushing and flossing. If, you have any tooth sensitivity or irritation of your soft tissue; gums; stop and advise the dentist.

Yes but...: It does appear to be rather strong, and it is probably better to get a supervised bleaching from your dentist, in the dental office.