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

Abstract Background 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. Methods 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. Results 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. Conclusion PBM can significantly reduce the overall amount of root resorption and enhance/accelerate the healing of OIIRR.