title: Three consecutive days of application of LED therapy is necessary to inhibit experimentally induced root resorption in rats: a microtomographic study.
abstract: Previous studies have suggested that phototherapy may modulate orthodontic tooth movement and the incidence of root resorption. We aimed to identify a minimal dose-response relationship to LED therapy with regard to orthodontic tooth movement (OTM) and root resorption in rats. Forty-eight male Wistar rats were divided into six groups with equal and random distribution: control (C) no intervention; three daily LED irradiation (CLED); submitted only to OTM (RR); OTM and LED irradiation on the first day (LED1); OTM and two LED irradiation on the first and second days (LED2); and OTM and three LED irradiation on the first, second, and third days (LED3). Orthodontic appliance was installed in groups RR, LED1, LED2, and LED3 to promote OTM. Animals from groups CLED, LED1, LED2, and LED3 received LED therapy (940 nm, 4 J, 4 J/cm2) according to each group of treatment. After 7 days, all the animals were sacrificed. The jaws were fixed and scanned with microtomography (micro-CT). The micro-CT images were reconstructed on 2D and 3D models. These models were used to identify and measure root resorption number and dimensions (diameter, depth, and volume). The distance between the first and second molars was used to verify tooth displacement. The results showed that LED3 group had significantly lower number of root resorption. The root resorption dimensions (diameter and depth) had no significant differences among the experimental groups. LED3 group had significant tooth displacement in relation to C and CLED groups. In conclusion, three daily LED therapy doses are required to inhibit root resorption after appliance of orthodontic forces.
authors: Department of Histology, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid PR 445 Km 380, CEP 86051-990, Londrina, PR, Brazil. daythyeme@gmail.com.
authors: Dayla Thyeme
authors: DT
authors: Higashi
authors: Department of Physics, Universidade Estadual de Londrina, Londrina, Brazil.
authors: Avacir Casanova
authors: AC
authors: Andrello
authors: Department of Oral Medicine and Pediatrics, Universidade Estadual de Londrina, Londrina, Brazil.
authors: Pedro Marcelo
authors: PM
authors: Tondelli
authors: Department of Physics, Universidade Estadual de Londrina, Londrina, Brazil.
authors: Dari
authors: D
authors: de Oliveira Toginho Filho
authors: Department of Histology, Universidade Estadual de Londrina, Rodovia Celso Garcia Cid PR 445 Km 380, CEP 86051-990, Londrina, PR, Brazil.
authors: Solange
authors: S
authors: de Paula Ramos
mesh_terms: D000818:Animals; D007249:Inflammation / Q000473:pathology; D008297:Male; D009967:Orthodontic Appliances / Q000009:adverse effects; D010789:Phototherapy / Q000379:methods*; D017208:Rats, Wistar; D012391:Root Resorption / Q000000981:diagnostic imaging* / Q000628:therapy*; D014087:Tooth Movement Techniques; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Low-level light therapy; Phototherapy; Root resorption; Tooth movement; Tooth resorption