Evaluation of the Pulp Oxygen Saturation Reading after Tooth Bleaching: A Randomized Clinical Trial

Abstract

Objectives. The purpose of this clinical trial was to evaluate the influence of in-office dental bleaching on the pulp oxygen saturation (SpO2p) reading. Material and Methods. SpO2p was measured using a pulse oximeter in 112 upper and lower anterior teeth (canines and incisors) of patients submitted to bleaching. Whitegold Office 35% (WGO) (upper and lower left hemiarch) and Whiteness HP Auto Mixx 35% (WHP) (upper and lower right hemiarch) bleaching agents were used. SpO2 measurements (teeth and index finger) were taken before and after each of the three application sessions of the agents. In the 4th session, in which no bleaching gel was used, only SpO2 was measured. Before and after the bleaching sessions, a colorimetric device performed the teeth color reading. The waiting time between sessions was 7 days. Data were analyzed by the Friedman, Kruskal–Wallis, and Mann–Whitney U tests (α = 0.05). Color change (ΔE) data were correlated (Spearman’s Rho test) with the SpO2p levels. Results. Neither of the two bleaching agents showed significant differences between the readings when evaluated individually (WGO, $P=0.780$ , and WHP, $P=0.494$ ). When taken together, the results showed significant difference between the readings performed, with higher median values after bleaching sessions: before (97.3) and after (98.6) 1st session; before (98.3) and after (98.3) 2nd session; before (98.3) and after (99.0) 3rd session; and after 1 week (98.3). The dental groups formed by maxillary lateral incisors ( $P=0.012$ ) and mandibular incisors ( $P<0.001$ ) showed a significant difference. Spearman’s Rho test showed a nonsignificant and weak correlation between ΔE and SpO2p in most comparisons. Conclusions. The in-office dental bleaching influenced the SpO2p reading, regardless of the dental group evaluated or the bleaching agent used. Clinical Relevance. This study provides information about the influence of in-office tooth whitening on the pulp SpO2p levels. The observation of pulp vitality during and after the use of bleaching agents is important for the follow-up of patients undergoing tooth whitening. The use of a pulse oximeter may be a viable and painless alternative to perform this monitoring. The clinical trial was registered with the Brazilian Registry of Clinical Trials (ReBEC; registration number: https://clinicaltrials.gov/ct2/show/RBR-68xbth).