Evaluation of an experimental rat model for comparative studies of bleaching agents.
Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats' vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents.
Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Luciano Tavares Angelo
LT
Cintra
Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Francine
F
Benetti
Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Luciana Louzada
LL
Ferreira
Departamento de Odontologia Restauradora, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Vanessa
V
Rahal
Departamento de Ciências Básicas, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Edilson
E
Ervolino
Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
Rogério de Castilho
Rde C
Jacinto
Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
João Eduardo
JE
Gomes Filho
Departamento de Odontologia Restauradora, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.
André Luiz Fraga
AL
Briso
D000818:Animals; D002452:Cell Count; D003782:Dental Pulp / Q000187:drug effects* / Q000473:pathology; D003786:Dental Pulp Cavity; D005347:Fibroblasts / Q000187:drug effects; D005782:Gels; D006861:Hydrogen Peroxide / Q000008:administration & dosage*; D008297:Male; D023421:Models, Animal; D009804:Odontoblasts / Q000187:drug effects; D017208:Rats, Wistar; D015203:Reproducibility of Results; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000008:administration & dosage*
D005782:Gels; D058205:Tooth Bleaching Agents; D006861:Hydrogen Peroxide