# Hyperbaric Oxygen Therapy to Minimize Orthodontic Relapse in Rabbits

## TL;DR

This study shows that hyperbaric oxygen therapy reduces orthodontic relapse in rabbits by affecting specific proteins and genes in gum tissues.

## Contribution

The study demonstrates a novel use of HBOT in orthodontics by linking it to changes in HIF-1α, Col I, and MMP-1.

## Key findings

- HBOT increased HIF-1α mRNA expression in rabbit gingival fibers.
- HBOT elevated collagen (Col I) and matrix metalloproteinase-1 (MMP-1) protein levels.
- HBOT significantly reduced orthodontic relapse in rabbits.

## Abstract

Objectives
 The purpose of the present study was to discover how hyperbaric oxygen therapy (HBOT) could reduce orthodontic relapse by altering the expressions of hypoxia-inducible factor (HIF)-1 messenger ribonucleic acid (mRNA), type I collagen (Col I), and matrix metalloproteinase-1 (MMP-1) in the gingival supracrestal fibers in rabbits.

Materials and Methods
 This study involved 44 male rabbits (
Oryctolagus cuniculus
) randomly divided into the normal group (K0), the orthodontic group without HBOT (K1), and the orthodontic group with HBOT (K2). Following orthodontic separation of the two upper central incisors, a retention phase and relapse assessment were performed. The HBOT was performed for a period of 2, 4, 6, 8, and 10 days after retention. HIF-1α transcription was assessed employing real-time polymerase chain reaction, whereas Col I and MMP-1 proteins were examined using immunohistochemistry. The orthodontic relapse was measured clinically using a digital caliper.

Statistical Analysis
 We used the one-way analysis of variance followed by Tukey's post hoc for multiple comparisons to measure differences between pairs of means; a
p-
value of 0.05 was considered statistically significant.

Results
 HBOT significantly increased the HIF-1α mRNA expression (
p
 = 0.0140), increased Col I (
p
 = 0.0043) and MMP-1 (
p
 = 0.0068) on the tensioned and pressured side of the gingival supracrestal fibers, respectively, and clinically decreased the relapse (
p
 = 3.75 × 10
−40
).

Conclusion
 HBOT minimizes orthodontic relapse by influencing HIF-1α expression, collagen synthesis (Col I), and degradation (MMP-1). This result suggests that HBOT has the potential to be used as an adjunctive method in the orthodontic retention phase.