Tooth sensitivity and whitening effect of an in-office bleaching gel containing sodium hexametaphosphate: A randomized triple-blind clinical trial

Dental sensitivity is one of the most prevalent clinical consequences among patients who receive in-office bleaching therapy. This study aimed to evaluate the effect of adding sodium hexametaphosphate (SHMP) to an in-office bleaching gel on tooth whitening and sensitivity after the treatment. 

The right and left maxillary lateral incisors of 34 patients were randomly divided into intervention and control groups. In the control side, a bleaching gel containing 37.5% hydrogen peroxide was used, whereas in the intervention side, a combination of the same bleaching gel with 1% SHMP was applied for 30 minutes. Tooth sensitivity to cold, tactile sensitivity, and spontaneous sensitivity was measured before the treatment, and immediately, 24 hours, one week, and one month after therapy. Color changes were measured objectively by a spectrophotometer using the total variation in color (ΔE), and subjectively by a Vita Classical Shade Guide (ΔSGU). 

Immediately after bleaching, cold and tactile sensitivity was higher in the control group compared with the intervention group, but there was no significant difference between groups in any of the sensitivity parameters at different measurement intervals (P>0.05). Spontaneous and tactile sensitivity decreased significantly in both groups over one month (P<0.05). There was no significant difference in ΔE and ΔSGU between the intervention and control groups (P>0.05). 

The addition of SHMP to the bleaching gel could not reduce sensitivity to cold, as well as tactile and spontaneous sensitivity; however, it showed no adverse effect on the bleaching effectiveness.