The Number of Bleaching Sessions Influences Pulp Tissue Damage in Rat Teeth

• Published in: Journal of endodontics Vol. 39; no. 12; pp. 1576 - 1580
• Main Authors: Cintra, Luciano Tavares Angelo, PhD, Benetti, Francine, DDS, da Silva Facundo, Aguinaldo Cândido, MSc, Ferreira, Luciana Louzada, MSc, Gomes-Filho, João Eduardo, PhD, Ervolino, Edilson, PhD, Rahal, Vanessa, PhD, Briso, André Luiz Fraga, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2013
• Subjects: Animals; Dental Pulp - drug effects; Dental Pulp Cavity - drug effects; Dental Pulp Necrosis - chemically induced; Dentin, Secondary - drug effects; Dentistry; Endocrinology & Metabolism; Hydrogen peroxide; Hydrogen Peroxide - administration & dosage; Hydrogen Peroxide - adverse effects; Male; Molar - drug effects; Odontoblasts - drug effects; pulp reaction; Pulpitis - chemically induced; Rats; Rats, Wistar; Time Factors; Tooth Apex - drug effects; tooth bleaching; Tooth Bleaching - methods; Tooth Bleaching Agents - administration & dosage; Tooth Bleaching Agents - adverse effects; Tooth Root - drug effects; pulp reaction; Hydrogen peroxide; tooth bleaching
• ISSN: 0099-2399; 1878-3554
• DOI: 10.1016/j.joen.2013.08.007

Abstract Introduction Hydrogen peroxide tooth bleaching is claimed to cause alterations in dental tissue structures. This study investigated the influence of the number of bleaching sessions on pulp tissue in rats. Methods Male Wistar rats were studied in 5 groups (groups 1S–5S) of 10 each, which differed by the number (1–5) of bleaching sessions. In each session, the animals were anesthetized, and 35% hydrogen peroxide gel was applied to 3 upper right molars. Two days after the experimental period, the animals were killed, and their jaws were processed for light microscope evaluation. Pulp tissue reactions were scored as follows: 1, no or few inflammatory cells and no reaction; 2, <25 cells and a mild reaction; 3, between 25 and 125 cells and a moderate reaction; and 4, 125 or more cells and a severe reaction. Results from each experimental group were compared between groups and within groups to the corresponding unbleached upper left molars and analyzed for significant differences using the Kruskal-Wallis test ( P < .05). Results All tissue sections showed significant bleaching-induced changes in the dental pulp. After 1 bleaching session, necrotic tissue in the pulp horns and underlying inflammatory changes were observed. The extent and intensity of these changes increased with the number of bleaching sessions. After 5 sessions, the changes included necrotic areas in the pulp tissue involving the second third of the radicular pulp and intense inflammation in the apical third. Conclusions The number of bleaching sessions directly influenced the extent of pulp damage.