Time to color stabilization during in-office bleaching with 35% hydrogen peroxide: A prospective clinical study

To characterize color change progression during in-office bleaching (IOB) and to estimate the median number of bleaching sessions to reach color stabilization across consecutive sessions. Tooth sensitivity (TS), gingival irritation (GI), pulp sensibility at 10 months and patient-reported esthetic outcomes were also evaluated.

This prospective, single-arm controlled trial enrolled 40 adults with canine shade A2 or darker. Participants underwent six IOB sessions with 35% hydrogen peroxide. Color change was assessed after each session using instrumental and visual metrics. Time to stabilization was analyzed using Kaplan-Meier methods; stabilization being the first session after which all subsequent inter-session changes remained below perceptibility thresholds (PT). TS and GI were recorded using visual analog scales. Orofacial Esthetic Scale (OES) was applied at baseline and after treatment. Pulp sensibility was checked after 10 months.

Using PT, only 18-25% of the participants stabilized color by third session. Shade-guide-based outcomes reached median stabilization at the second-third session. Under acceptability thresholds (AT), median stabilization occurred at the third session. TS and GI were transient, mild, with no evidence of cumulative worsening (p < 0.05). All recalled patients (28/40) showed positive normal pulpal response. All OES items improved significantly from baseline to post-treatment (p < 0.05).

Color stabilization is dependent on thresholds used. Half of participants stabilized by third week using AT and shade guide units as reference. TS and GI were mild, with positive pulp sensibility. High patient satisfaction was observed.

Decisions on IOB duration should be guided by patient's bleaching response, expectations, and adverse effects.