# Effect of photobiomodulation therapy on orthodontic-induced inflammatory root resorption in male albino rats

## TL;DR

This study shows that photobiomodulation therapy can reduce root resorption in rats caused by orthodontic forces.

## Contribution

The study demonstrates that PBM reduces orthodontic-induced root resorption and accelerates healing in rats.

## Key findings

- PBM significantly decreased root resorption at day 21 in all force subgroups.
- PBM enhanced healing and tissue regeneration during orthodontic tooth movement.
- PBM improved blood supply and tissue reorganization in periodontal tissues.

## Abstract

This study aimed to assess histologically and histomorphometrically the effect of Photo-biomodulation therapy (PBM) on orthodontic-induced inflammatory root resorption (OIIRR) under relatively light- and heavy- orthodontic forces in rats.

Thirty-two male Albino rats weighing between (250–300 g) were randomly assigned to four equal groups (gp) of 8 rats each. Control low-force gp (CL): The maxillary left 1st molar (M1) was subjected to 10–15 g orthodontic force by nickel titanium coil spring stretched between the M1 and maxillary incisors. Control high-force gp (CH): The M1 had heavier orthodontic force of 50 g. Laser low-force gp (LL): The M1 had orthodontic force of 10–15 g & PBM using GaAlAs diode laser (λ = 980 nm, 100 mW output power) at two points palatal and two buccal, with a continuous non-contact irradiating mode for 12 s for each point (energy of 1.2 J/point, fluence of 16.9 J/cm2). Laser high-force gp (LH): M1 had orthodontic force of 50 g & PBM. The rats were euthanized after 7- and 21-days intervals in each gp and the maxillae were dissected out, then serial transverse sections of the M1 were taken for histological and histomorphometric evaluation.

Our results showed significant decrease in the amount of OIIRR in the laser gps at day 21 in all force subgroups, without significant change at day 7.

PBM can significantly reduce the overall amount of root resorption and enhance/accelerate the healing of OIIRR.

The online version contains supplementary material available at 10.1186/s12903-025-07217-2.

• Photo-biomodulation (PBM) reduces the amount of orthodontic root resorption.

• PBM accelerates the tissue events during the orthodontic tooth movement (OTM).

• PMB improves the periodontal tissue blood supply and its related tissue events.

• PBM enhances regeneration and reorganization of the periodontal tissues after OTM.

The online version contains supplementary material available at 10.1186/s12903-025-07217-2.