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Time to saturation point in tooth-bleaching protocols: An in vitro study
Michael Willian Favoreto1, Nicolly Barchiki2, Maria Eduarda Cavassin2
1Department of Restorative Dentistry, Tuiuti University of Paraná, Paraná, Brazil; Now with Department of Restorative Dentistry, University of São Paulo, São Paulo, Brazil.
Journal of the American Dental Association (1939)
|July 20, 2026
Summary
The saturation point for tooth bleaching is threshold-dependent, not differing between in-office and at-home methods. Clinicians should observe visible color changes rather than adhering to a fixed bleaching duration.
Area of Science:
- Dental materials science
- Aesthetic dentistry
- Biomaterials research
Background:
- The saturation point of tooth bleaching lacks objective definition in scientific literature.
- This study aimed to define and characterize the color stabilization phase during dental bleaching procedures.
Purpose of the Study:
- To characterize the color change pattern over time during dental bleaching.
- To determine the time to clinically perceptible stabilization (saturation point) for both in-office and at-home bleaching protocols.
Main Methods:
- Sixty extracted human molars underwent either in-office bleaching (IOB) or at-home bleaching (AHB) for 8 cycles.
- Tooth color was objectively measured using spectrophotometry (ΔEab, ΔE00, ΔWID) and shade guide units (ΔSGUs).
- Stabilization was defined by intercycle color changes falling below perceptibility (PT) and acceptability (AT) thresholds.
Main Results:
- Using the perceptibility threshold (PT), stabilization was observed in a minority of specimens for spectrophotometric measures, with no defined median time.
- Shade guide units (ΔSGUs) stabilized in all specimens within 3-4 cycles.
- Under the acceptability threshold (AT), most specimens stabilized within 5-7 cycles, with no significant difference between IOB and AHB.
- One in-office bleaching session yielded approximately 85% of the color change from one week of at-home bleaching.
Conclusions:
- Tooth color stabilization during bleaching is dependent on the chosen threshold (PT or AT).
- No significant difference in stabilization time was found between in-office and at-home bleaching protocols.
- Clinical decisions regarding bleaching duration should be based on observed visual changes rather than predetermined treatment lengths.
