Watts Power 35% Teeth Whitening Gels If you want dentist white teeth, try this. Even as a dentist, Dr. Watts does not recommend teeth whitening strengths higher than 35% carbamide peroxide. This optimized 35% formula offers the same results as higher strengths but without the sting or harsh side effects. Bonus, our thicker gel sticks to teeth for quicker results and less mess. So, smile big with our strongest 35% teeth whitening gels. Please note that NOT all options include teeth whitening trays. If you need trays be sure to select the combo kit option that includes teeth trays and gels or add the 8 pack trays to any size gel order.