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

https://telegra.ph/Why-Professional-Whitening-is-Safer-for-Your-Enamel-04-15

If you clench or grind, discuss it before whitening; enamel wear and exposed dentin can heighten sensitivity, needing customized procedures and gentler gels.