Human Dental Pulp Tissue during Orthodontic Tooth Movement: An Immunofluorescence Study

Abstract

The orthodontic tooth movement is the last step of several biological processes that take place after the application of external forces. During this process, dental pulp tissue is subjected to structural and protein expression modifications in order to maintain their integrity and functional morphology. The purpose of the present work was to perform an in vivo study, evaluating protein expression modifications in the human dental pulp of patients that have undergone orthodontic tooth movement due to pre-calibrated light force application for 30 days. Dental pulp samples were extracted from molars and premolars of the control group and after 7 and 30 days of treatment; the samples were then processed for immunofluorescence reactions using antibodies against fibronectin, collagen I and vascular endothelial growth factor (VEGF). Our results show that, after 7 days of treatment, all tested proteins change their pattern expression and will reset after 30 days. These data demonstrate that the dental pulp does not involve any irreversible iatrogenic alterations, supporting the efficacy and safety of using pre-calibrated force application to induce orthodontic tooth movement in clinical practice.

Keywords: extracellular matrix proteins; human dental pulp; immunofluorescence; orthodontic tooth movement.

Figure 1

Compound panel of immunofluorescence reaction pictures that show fibronectin staining pattern in human dental pulp after 7 (A), 14 (C) and 30 (E) days after pre-calibrated force application and the corresponding transmitted light observations (B,D,F). The following magnifications have been used: 40× (A,B), 20× (C–F).

Figure 2

Compound panel of immunofluorescence reaction pictures that show collagen I staining pattern (red channel) in human dental pulp after 7 (A), 14 (C) and 30 (E) days after pre-calibrated force application and the corresponding transmitted light observations (B,D,F). The following magnifications have been used: 40× (A,B), 20× (C–F).

Figure 3

Compound panel of immunofluorescence reaction pictures that show VEGF staining pattern in human dental pulp after 7 (A), 14 (C) and 30 (E) days after pre-calibrated force application and the corresponding transmitted light observations (B,D,F). The following magnifications have been used: 10× (A,B), 20× (C–F).

Figure 4

Graphic that shows the means of fibronectin expression (blue columns) at 7, 14 and 30 days. The Analysis of Variance (ANOVA) test showed a significant statistical difference among the means obtained at 7, 14 and 30 days of treatment (p-value < 0.05).

Figure 5

Graphic that shows the means of collagen I expression (blue columns) at 7, 14 and 30 days. The ANOVA test showed a significant statistical difference among the means obtained at 7, 14 and 30 days of treatment (p-value < 0.05).

Figure 6

Graphic that shows the means of VEGF expression (blue columns) at 7, 14 and 30 days. The ANOVA test showed a significant statistical difference among the means obtained at 7, 14 and 30 days of treatment (p-value < 0.05).