title: The promoting effect of carbamide peroxide teeth bleaching gel in a preclinical model of head and neck cancer in hamster buccal pouch.
abstract: OBJECTIVE
  The aim of this study was to verify the promoting effect of carbamide peroxide on dimethylbenzanthracene (DMBA)-induced carcinogenesis in the hamster buccal pouch, in order to reduce the period of latency for tumor formation.
  
  
  METHODS
  Sixteen hamsters were randomized into two groups of eight animals each. The hamsters of the group I had their right buccal pouches treated with 0.5% DMBA and 10% carbamide peroxide teeth bleaching gel for 55 days. The animals of the group II had their right pouches treated only with DMBA. After, six animals of each group had their pouches prepared for light microscopy. Histomorphometry was performed to assess the presence of keratinization, nuclear polymorphism, pattern of invasion, number of blood vessels, and inflammatory infiltrate in the tumor front. Furthermore, the newly formed lesions were graded according the Bryne's grading system. The remaining animals had the vascular system of the pouches casted by Mercox and qualitatively analyzed by scanning electron microscopy.
  
  
  RESULTS
  Histopathological analysis of the buccal pouches treated with DMBA and carbamide peroxide exhibited formation of squamous cell carcinoma well-differentiated with a high degree of malignancy in all pouches. The development of this neoplasm was associated with a significant increase in the number of blood vessels, presence of keratin pearls, and inflammatory infiltrate. The pouches of the group II showed inflammation, epithelial hyperplasia, dysplasia, and squamous cell carcinoma in only three right pouches. The analysis of the electron micrographs of the pouches chemically inducted with DBMA and carbamide peroxide reveled formation of a new vascular network characteristic of squamous cell carcinoma.
  
  
  CONCLUSIONS
  The protocol presented here, using DMBA associated with carbamide peroxide, shortens the period of latency to produce squamous cell carcinoma in the hamster buccal pouch, decreasing the time and costs of the experiments.
authors.affiliation: Laboratory of Medical Skills and Surgical Research, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Vinícius
authors.initials: V
authors.lastname: Faccin Bampi
authors.affiliation: Department of Food Sciences, Federal University of Lavras, Lavras, Brazil.
authors.forename: Wadson
authors.initials: W
authors.lastname: Ferreira Vilela
authors.affiliation: Department of Morphology Science, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Reggiani
authors.initials: R
authors.lastname: Vilela Gonçalves
authors.affiliation: Department of Morphology Science, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Maria Gabriela
authors.initials: MG
authors.lastname: Tavares Rheingantz
authors.affiliation: Department of Morphology Science, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: Minello
authors.affiliation: Department of Surgery, Faculty of Medicine, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Jefferson Luis
authors.initials: JL
authors.lastname: Braga da Silva
authors.affiliation: Department of Morphology Science, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Laura Beatriz
authors.initials: LB
authors.lastname: Oliveira de Oliveira
keywords: Carbamide peroxide; Carcinogens; Dimethylbenzanthracene; Hamster