VOLUME 40 • NUMBER 3 • MARCH 2009 195 QUINTESSENCE INTERNATIONAL Since its introduction by Haywood and Heymann, 1 home dental bleaching has been the most commonly used method for tooth whitening. The original technique, published in 1989, used 10% carbamide peroxide in a vacuum-formed custom tray. Nightguard vital bleaching is an effective and simple method of lightening extrinsically stained or discol- ored teeth. 2 One of the changes in the origi- nal technique has been the use of carbamide peroxide in concentrations greater than 10%, claiming greater effectiveness and less time. 3 However, several studies have reported important adverse effects, such as tooth sen- sitivity, 4–8 soft tissue changes, 9,10 hard tissue changes, 11,12 genotoxic effect in bacteria and cultured cells, 13–15 cytotoxic effects, 16,17 and gingival irritation, 3,7–9,18–21 due to multiple and prolonged exposures of bleaching agents. According to Haywood et al, 2 approximately two-thirds of patients who undergo bleaching treatment with carbamide peroxide experi- ence tooth and/or gingival sensitivity. Gingival Effect of reservoirs on gingival inflammation after home dental bleaching Giovanna A. Kirsten, DDS 1 /Andrea Freire, DDS 2 / Antonio Adilson S. de Lima, DDS, MDS, PhD 3 / Sergio Aparecido Ignácio, DDS, MDS, PhD 4 / Evelise M. Souza, DDS, MDS, PhD 4 Objective: To evaluate the influence of reservoirs on the gingival mucosa of patients sub- mitted to at-home bleaching with 16% carbamide peroxide. Method and Materials: Nineteen nonsmoking male patients, 18 to 25 years of age, were submitted to home bleaching with a 16% carbamide peroxide gel for 2 consecutive hours for 21 days. The custom-made mouth trays were made with a reservoir on only the left side and cut anatom- ically 1 mm beyond the gingival margin. Smears of the gingival mucosa were obtained by the exfoliation cytology in liquid media technique before (control), immediately after, and 30 and 45 days after treatment. The samples were processed in the laboratory and evalu- ated according to Papanicolaou’s criteria of malignity. Statistical analysis was carried out by McNemar test, 2 proportions test, and Wilcoxon test with a level of significance of 1%. Results: The presence of a reservoir in the custom tray resulted in an increase of inflam- mation only immediately after the bleaching procedure. After 30 and 45 days, the differ- ence between inflammation on the sides with and without a reservoir was not statistically significant. Significant differences were found in the degree of inflammation, classified as predominantly mild on the nonreservoir side and moderate on the reservoir side (P < .01). Conclusions: A 16% carbamide peroxide bleaching gel caused gingival inflammation immediately after the procedure and persisted until 45 days after the bleaching treatment. The use of a reservoir in the custom tray for home bleaching resulted in higher rates and higher intensity of gingival inflammation. (Quintessence Int 2009;40:195–202) Key words: carbamide peroxide, dental bleaching, exfoliative cytology, gingival inflammation, reservoir, tray 1 MDS student, School of Dentistry, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil. 2 PhD student, School of Dentistry, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil. 3 Professor, School of Dentistry, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil. 4 Adjunct Professor, School of Dentistry, Pontifical Catholic University of Paraná, Curitiba, Paraná, Brazil. Correspondence: Dr Evelise M. Souza, Programa de Pos-gradu- ação em Odontologia, School of Dentistry, Pontifical Catholic University of Paraná, R. Imaculada Conceição, 1155, Curitiba— PR—Brazil 80215-901. Fax: 55 41 3271-1405. Email: evesouza@ yahoo.com