Effect of Photobiomodulation Therapy on Orthodontic-Induced Inflammatory Root Resorption in Male Albino Rats

Background : This study aimed to assess histologically and histomorphometrically the effect of Photo-biomodulation therapy (PBMT) 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 1 ^st 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 & PBMT 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 seconds for each point (energy of 1.2 J/point, fluence of 16.9 J/cm ² ). Laser high-force gp (LH): M1 had orthodontic force of 50 g & PBMT. 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 : PBMT can significantly reduce the overall amount of root resorption and enhance/accelerate the healing of OIIRR.