Potassium Oxalate and Placebo and Post-bleaching Sensitivity

"* Teeth will be cleaned using rubber cups associated to pumice and water~* Relative isolation with roller cotton will be done;~* Prior to each bleaching session, the patients will receive the potassium OXALATE 5%~* Gingival dam will be performed using a fluid resin (Top Dam, FGM, Brazil) desensitivity gel application on vestibular surface, for 10 minutes.~* A 35% hydrogen peroxide based bleaching agent will be mixed and applied on the vestibular surface of teeth, remaining for 40 minutes."

"* Teeth will be cleaned using rubber cups associated to pumice and water~* Relative isolation with roller cotton will be done;~* Prior to each bleaching session, the patients will receive the placebo gel~* Gingival dam will be performed using a fluid resin (Top Dam, FGM, Brazil) desensitivity gel application on vestibular surface, for 10 minutes.~* A 35% hydrogen peroxide based bleaching agent will be mixed and applied on the vestibular surface of teeth, remaining for 40 minutes."