# Evaluating the Injection of Platelet-Rich Plasma on Second Lower Molars Protraction: A Randomized Controlled Clinical Trial

## TL;DR

This study found that injecting platelet-rich plasma does not speed up or change the movement of lower molars during orthodontic treatment.

## Contribution

The study provides new clinical evidence that PRP injection does not influence the rate or type of molar protraction in orthodontics.

## Key findings

- PRP injection did not significantly affect the rate of molar protraction compared to saline.
- Both groups showed similar tooth movement patterns, close to bodily movement.

## Abstract

Background

The use of platelet-rich plasma (PRP) in dentistry was entered several decades ago, yet its clinical use in orthodontics still requires further investigation. The aim of this study was to evaluate the possible effects of local injection of PRP on the rate and type of mandibular second molar protraction movement compared with the comparator (no PRP) group.

Material and methods

Eighteen patients aged between 17 and 25 years were randomly allocated in a split-mouth study design to receive PRP injections on one side immediately before the start of molar protraction (PRP group), while the other side received only saline solution (comparator group). Eligibility criteria included bilaterally extracted mandibular first molars cases and indicated mandibular second molars protraction. The primary outcome of the study consisted of measuring the rate of molar protraction from the beginning of protraction (T0) to the end of the seventh month (TF), using a digital gauge. The secondary outcome included measuring the type of second molar protraction movement between T0 and TF by lateral cephalometric images. Randomization of the intervention side was performed by picking out opaque sealed envelopes. The blinding of the principal investigator was impossible but blinding of the patient was achieved by injection of saline. Analyses were done using paired samples T-test to compare the changes in all variables between T0 and TF. The level of significance was taken at a P-value < 0.05.

Results

No significant difference was detected between the PRP and comparator groups in the rate of second lower molar protraction during seven months (0.56±0.07 mm per month in the comparator group, whereas, was 0.6±0.11 mm per month in the PRP group). Molar protraction parameters in both groups showed second lower molars moving by controlled tipping closer to bodily movement (Root Movement:Crown Movement≈0.8).

Conclusions

Platelet-rich plasma (PRP) is ineffective in accelerating the rate of orthodontic tooth movement (OTM) during molar protraction, and it has no effect on the type of tooth movement. In addition, the mechanics that we used (6 mm power arm in combination with miniscrews) are effective in mandibular second molar protraction by controlled tipping closer to bodily movement.