If you clench or grind, discuss it before whitening; enamel wear and exposed dentin can increase sensitivity

https://blogfreely.net/dernesvhbz/do-whitening-strips-in-fact-work-a-dental-professionals-viewpoint

If you clench or grind, discuss it before whitening; enamel wear and exposed dentin can increase level of sensitivity, needing personalized procedures and gentler gels.