The effect of intrusive orthodontic force on dental pulp of adults versus adolescents

Mostafa Abtahi, Neda Eslami, Reza Zare Mahmoud Abadi, Saber Pooria Rezaei


Background: There is no conclusive evidence on the effect of orthodontic force application on

dental pulp tissue. The aim of this study was to compare early and delayed histological effects of

intrusive forces on dental pulp of adolescents and adults.

Materials and Methods: Patients referred to the Department of Orthodontics of

Mashhad University of Medical Sciences participated in this study. They were assigned to

adult (25–32‑year‑old) and adolescent (13–18‑year‑old) Groups. A cantilever spring made of 16 × 22

steel wire was used to apply intrusive force to upper first premolars (11 teeth in adolescents and

11 teeth in adults) and the opposing teeth were considered as control group. In each group, 6 pairs

of teeth were extracted after one week, and the remaining 5 pairs were extracted after one month

of intrusion. Histologic changes were compared between the control and intrusive groups and also

between the adults and adolescents after 7 days and 1 month. Statistical analysis was performed

using Statistical Package for the Social Sciences and Wilcoxon

and Mann–Whitney U‑tests. P ≤ 0.05 was set as statistically significant.

Results: Significant difference was not found in any histological parameters between intrusive

and control groups 1 week and 1 month after intrusion in adolescents and adults (P > 0.05). One

month after intrusion, inflammatory cell response intensity (P = 0.032) and frequency of chronic

inflammation (P = 0.032) were significantly higher in adults compared to adolescents.

Conclusion: Mild intrusive force in closed apex teeth causes no significant histologic changes in

adolescents and adults. However, it seems that inflammatory‑related histologic pulpal changes are

more severe in adults after one month of intrusion.

Key Words: Dental pulp, histology, intrusion

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