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Effect of acidity of in-office bleaching gels on tooth sensitivity and whitening: a two-center double-blind randomized clinical trial



The study aimed to compare the tooth sensitivity (TS) and bleaching efficacy of two hydrogen peroxide gels with different pHs (acid pH [Pola Office, SDI] and the neutral pH [Pola Office+, SDI]) used for in-office bleaching.

Materials and methods

Fifty-four patients from Brazil and Chile, with right superior incisor darker than A2, were selected for this double-blind, split-mouth randomized trial. Teeth were bleached in two sessions, with 1-week interval. Each session had three applications of 8 min each, according to the manufacturer’s instructions. The color changes were evaluated by subjective (Vita Classical and Vita Bleachedguide) and objective (Easy shade spectrophotometer) methods. Participants recorded TS with 0–10 visual analog scale. Color change in shade guide units (SGU) and ΔE was analyzed by Student’s t test (α = 0.05). The absolute risk and intensity of TS were evaluated by McNemar’s test and Wilcoxon-paired test, respectively (α = 0.05).


All groups achieved the same level of whitening after 30 days of clinical evaluation. The use of a neutral in-office bleaching gel significantly decreases the absolute risk of TS (28%, 95% CI 18–41) and intensity of TS when compared to the acid bleaching gel (absolute risk of 50%, 95% CI 37–63).


The use of a neutral in-office bleaching agent gel produced the same whitening degree than an acid bleaching gel but with reduced risk and intensity of tooth sensitivity.

Clinical significance

Clinicians should opt to use in-office bleaching with a neutral gel than an acid product because the former causes a significant lower risk and intensity of tooth sensitivity.

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Corresponding author

Correspondence to A. D. Loguercio.

Ethics declarations

Conflict of interest

A. Loguercio declares that he has no conflict of interest, F. Servat declares that he has no conflict of interest, R. Stanislawczuk declares that he had no conflict of interest, A. Mena-Serrano declares that she has no conflict of interest, M. Rezende declares that she has no conflict of interest, M. V. Prieto declares that she has no conflict of interest, V. Cereño declares that she has no conflict of interest, M. F. Rojas declares that she has no conflict of interest, K. Ortega declares that she has no conflict of interest, E. Fernández declares that he has no conflict of interest, and A. Reis declares that she has no conflict of interest.


The work was partially supported by National Council for Scientific and Technological Development under grants 304105/2013-9 and 305588/2014-1.

Ethical approval

This clinical study was approved by the Ethics Committee of The Center of Higher Education of Campos Gerais (CESCAGE, protocol 390.941) and the University of Chile (protocol 2013/41) and was conducted according to the Consolidated Standards of Reporting Trials Statement and Helsinki Declaration of 1975 revised in 2000.

Informed consent

All persons gave their informed consent prior to their inclusion in the study. Details that might disclose the identity of the subjects under study were omitted.

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Loguercio, A.D., Servat, F., Stanislawczuk, R. et al. Effect of acidity of in-office bleaching gels on tooth sensitivity and whitening: a two-center double-blind randomized clinical trial. Clin Oral Invest 21, 2811–2818 (2017).

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  • In-office bleaching
  • Neutral gel
  • Acidic gel
  • Tooth sensitivity
  • Whitening effectiveness