Effects of the photobiomodulation using different energy densities on the periodontal tissues under orthodontic force in rats with type 2 diabetes mellitus

Abstract

To evaluate the impact of the GaAlAs diode laser with energy densities of 160 J/cm 2 , 320 J/cm 2 , and 640 J/cm 2 on the periodontal tissues under continuous orthodontic force application and on the rate of orthodontic tooth movement in rats with type-2 diabetes mellitus. The intensity of primary alveolar bone formation was also investigated through the immune-positive osteocytes for OPN antibody. Forty adult male Wistar rats were divided into eight groups of 5 rats: normoglycemic (N), 160 J-laser-normoglycemic (160 J-LN), 320 J-laser-normoglycemic (320 J-LN), 640 J-laser-normoglycemic (640 J-LN), diabetic (D), 160 J-laser-diabetic (160 J-LD), 320 J-laser-diabetic (320 J-LD), and 640 J-laser-diabetic (640 J-LD) rats. Diabetes mellitus was induced by a single intravenous injection of 40 mg/kg monohydrated-alloxan. An orthodontic force magnitude of 20cN was applied. The laser parameters were continuous emission of 780-nm wavelength, output power of 20mW, and fiber probe with a spot size of 0.04 cm in diameter. Radiographic, histomorphological, and immunohistochemical analysis were performed after a period of 21 days. The photobiomodulation using the energy density of 640 J/cm 2 strongly stimulated the alveolar bone formation and contributed the reorganization of the soft periodontal tissues, followed by the 320 J/cm 2 . Extensive alveolar bone loss, intense infiltration of inflammatory cells, and degradation of the PDJ tissue were mainly found in the D and 160 J-LD groups. The rate of orthodontic tooth movement was represented by the interdental distance between the cementoenamel junctions of the right mandibular first and second molars. This distance was larger in the diabetic groups (D: 39.98±1.97, 160 J-LD: 34.84±6.01, 320 J-LD: 29.82±1.73, and 640 J-LD: 35.47±4.56) than in the normoglycemic groups (N: 21.13±1.19; 160 J-LN: 22.69±0.72, 320 J-LN: 22.28±0.78, and 640 J-LN: 24.56±2.11). The number of osteopontin-positive osteocytes was significantly greater in the 640 J-LD (14.72 ± 0.82; p < 0.01) and 640 J-LN (13.62 ± 1.33; p < 0.05) groups than with D (9.82 ± 1.17) and 160 J-LD (9.77 ± 1.10) groups. Therefore, the energy density of 640 J/cm 2 provided the best maintenance and integrity of the periodontal tissue microarchitecture under continuous orthodontic force when compared with the other dosages, mainly in the uncontrolled diabetic rats. The interdental distance was greater in the D and 160 J-LD groups due to presence of severe periodontitis caused by diabetes plus the mechanical stress generated by continuous orthodontic forces, implying, thus, an insufficient biostimulatory effect for the dosage of 160 J/cm 2 .

Evidence on the effect of uncontrolled diabetes mellitus on orthodontic tooth movement. A systematic review with meta-analyses in pre-clinical in- vivo research

“…Only one meta-analysis comprising of two studies was indicative of a decreased tendency for osteoblastic differentiation, related to the key marker gene of osteopontin when diabetic status was considered. Although the findings of both studies (Gomes et al, 2017(Gomes et al, , 2018 were indicative for a similar direction of the effect, the overall pooled estimate should be interpreted with caution, as these studies might have shared an experimental group; efforts were made to communicate with authors, however, they were unsuccessful.…”

“…It is interesting that of the six studies combined, only one revealed no difference (Ferreira et al, 2018). Three of the studies (Damanakis, 2018;Gomes et al, 2018;Mena Laura et al, 2019) reported a significant effect of hyperglycemic status to promote increased tooth movement, while the other two revealed completely opposite findings (Arita et al, 2016;Santamaria-Jr et al, 2019). Only one of those studies assessed the magnitude of root resorption at the end of the corresponding tooth movement (Arita et al, 2016).…”

“…After electronic database and hand-searching, a total of 290 eligible articles were retrieved, with 19 papers left for full-text evaluation after duplicate removal, title and abstract screening. Finally, five articles were excluded for reasons related to our pre-defined eligibility criteria, leaving a number of 14 articles for inclusion in this systematic review (Figure 1) (Arita et al, 2016;Braga et al, 2011;Damanakis, 2018;Ferreira et al, 2018;Gomes et al, 2017Gomes et al, , 2018Li, Zhang, Wang, Feng, & Bi, 2010;Maulana, Hikmah, Shita, Permatasari, & Widyarti, 2014;Mena Laura et al, 2019;Plut et al, 2015;Santamaria-Jr et al, 2019;Sun et al, 2017;Villarino et al, 2011;Zhang, Li, & Bi, 2011).…”

“…All but one study (Braga et al, 2011), recruited rats as animal models and specifically Wistar rats or Sprague-Dawley species (Arita et al, 2016;Damanakis, 2018;Ferreira et al, 2018;Gomes et al, 2017Gomes et al, , 2018Li et al, 2010;Maulana et al, 2014;Mena Laura et al, 2019;Plut et al, 2015;Santamaria-Jr et al, 2019;Sun et al, 2017;Villarino et al, 2011;Zhang et al, 2011). Braga et al, ( 2011) (Braga et al, 2011) recruited mice.…”

“…In total, nine articles contributed to meta-analyses (Arita et al, 2016;Damanakis, 2018;Ferreira et al, 2018;Gomes et al, 2017Gomes et al, , 2018Mena Laura et al, 2019;Santamaria-Jr et al, 2019;Sun et al, 2017;Villarino et al, 2011), while there was a variable amount of outcomes across the included studies. Decision for mathematical synthesis of studies was made after consideration of the apparent homogeneity of the eligible studies.…”