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Evaluation of an experimental rat model for comparative studies of bleaching agents.

Cintra LT, Benetti F, Ferreira LL, Rahal V, Ervolino E, Jacinto Rde C, Gomes Filho JE, Briso AL - J Appl Oral Sci (2016)

Bottom Line: Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05).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.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.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Representative images of hematoxylin & eosin-stained sections showing the coronal pulp 30 days after bleaching. Panels A, B, C, D, and E represent the groups treated with 20% H2O2 gel and panels F, G, H, I, and J represent those treated with 35% H2O2 gel for 5, 10, 15, 30, and 45 min, respectively (100× magnification). Panels a–j are magnified images (400×) of the insets in panels A–J, respectively. Stars indicate the reparative dentin layer; asterisks indicate the predentin layer. The values of the pulp chamber area were obtained as shown in Figure 1 to carry out the statistical analysis
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f04: Representative images of hematoxylin & eosin-stained sections showing the coronal pulp 30 days after bleaching. Panels A, B, C, D, and E represent the groups treated with 20% H2O2 gel and panels F, G, H, I, and J represent those treated with 35% H2O2 gel for 5, 10, 15, 30, and 45 min, respectively (100× magnification). Panels a–j are magnified images (400×) of the insets in panels A–J, respectively. Stars indicate the reparative dentin layer; asterisks indicate the predentin layer. The values of the pulp chamber area were obtained as shown in Figure 1 to carry out the statistical analysis

Mentions: Thirty days after the bleaching sessions, all the specimens showed normal dental pulp. However, the central area of the pulp chamber reduced, and the tertiary dentin area increased (Figure 4).


Evaluation of an experimental rat model for comparative studies of bleaching agents.

Cintra LT, Benetti F, Ferreira LL, Rahal V, Ervolino E, Jacinto Rde C, Gomes Filho JE, Briso AL - J Appl Oral Sci (2016)

Representative images of hematoxylin & eosin-stained sections showing the coronal pulp 30 days after bleaching. Panels A, B, C, D, and E represent the groups treated with 20% H2O2 gel and panels F, G, H, I, and J represent those treated with 35% H2O2 gel for 5, 10, 15, 30, and 45 min, respectively (100× magnification). Panels a–j are magnified images (400×) of the insets in panels A–J, respectively. Stars indicate the reparative dentin layer; asterisks indicate the predentin layer. The values of the pulp chamber area were obtained as shown in Figure 1 to carry out the statistical analysis
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836925&req=5

f04: Representative images of hematoxylin & eosin-stained sections showing the coronal pulp 30 days after bleaching. Panels A, B, C, D, and E represent the groups treated with 20% H2O2 gel and panels F, G, H, I, and J represent those treated with 35% H2O2 gel for 5, 10, 15, 30, and 45 min, respectively (100× magnification). Panels a–j are magnified images (400×) of the insets in panels A–J, respectively. Stars indicate the reparative dentin layer; asterisks indicate the predentin layer. The values of the pulp chamber area were obtained as shown in Figure 1 to carry out the statistical analysis
Mentions: Thirty days after the bleaching sessions, all the specimens showed normal dental pulp. However, the central area of the pulp chamber reduced, and the tertiary dentin area increased (Figure 4).

Bottom Line: Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05).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.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.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Endodontia, Faculdade de Odontologia de Araçatuba, Univ. Estadual Paulista, Araçatuba, SP, Brasil.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus