Systemic effects of LLLT on bone repair around PLLA–PGA screws in the rabbit tibia

Abstract

To evaluate the systemic effects of low level laser therapy (LLLT) on the early stages of bone repair after implantation of poly-L-lactic/polyglycolic acid (PLLA-PGA) screws 24 rabbits were randomly allocated to one of two groups, experiment or control. Each animal underwent implantation of one 5 × 1.5 mm PLLA-PGA screw in each tibia (right and left). The experiment group received infrared laser irradiation (830 nm, 4 J, 100 mW, 10.1 s) over the right paw immediately after implantation and every 48 h thereafter, for a maximum of seven sessions. The control group was not irradiated. Both groups were divided into three subgroups according to the observation period (5, 15, or 30 days), after which animals were euthanized. The results observed in the left paw of experimental animals were compared with the left paws of control animals. We also compared the right and left paws of experimental animals so as to compare local and potential systemic effects. Bone specimens were analyzed to assess the extent of peri-implant bone formation, quantitative analysis revealed greater bone formation in the left tibia of experimental animals as compared to controls on 5-day follow-up. Descriptive analysis revealed slightly larger and thicker trabeculae in the irradiated animals at 5 days post-procedure. There were no significant differences at any other point in time. As used in this study, LLLT had a positive systemic effect on the early stages of bone formation.

Effect of Three Different Protocols of Low-Level Laser Therapy on Thyroid Hormone Production After Dental Implant Placement in an Experimental Rabbit Model

“…12 We assumed that LLLT applied to the lower face could lead to indirect exposure of the thyroid gland, as 830 nm wavelength lasers can reach deeper planes and exert both local and systemic effects. 5,6,[28][29][30]36,38 The rabbit model was chosen because of the previously reported ease of handling, surgical preparation, and postoperative follow-up. 8,28,34,38 Moreover, the size of these animals enabled the use of conventional implants available for clinical use in humans.…”

“…5,6,[28][29][30]36,38 The rabbit model was chosen because of the previously reported ease of handling, surgical preparation, and postoperative follow-up. 8,28,34,38 Moreover, the size of these animals enabled the use of conventional implants available for clinical use in humans. As for implant placement in fresh tooth extraction sockets, we chose this method of implant placement, rather than the tibia (which is the most common site reported in the literature), in order to provide the closest possible simulation of a clinical situation.…”

“…These procedures would not be possible in rats or mice. 9,10,13,40 In accordance with the most recent literature, LLLT was delivered by an infrared laser [7][8][9][10][11][12][13][14][15][26][27][28]35,38 of 830 nm wavelength 7,10,[12][13][14][15] and 50 mW output power in two sites near the mandibular implant, in seven sessions 7,11,12,15 every 48 h, using three different doses. The use of a sham surgery and sham LLLT control group (C-I), as well as a baseline surgery but sham LLLT group (C-II), enabled us to isolate both the influence of baseline surgery and the systemic effects of LLLT.…”

“…5,[28][29][30] Therefore, LLLT may lead to effects on organs and tissues far from the actual site of application (systemic effects). The literature suggests that LLLT may have repercussions on endocrine function because of potential effects on the secretory glands, 31 including the thyroid gland.…”

Experimental burns: Comparison between silver sulfadiazine and photobiomodulation

“…However, in this study, it could be observed in the group that was irradiated. A systemic effect of photobiomodulation has been observed when applied to bone tissue, according to the work of Coelho et al 20 Another important point to be considered is the dosimetry delivered to the tissue, given that the irradiation parameters were taken from a study that used cold burn instead of scalding. 13 In burns caused by scalding there is dissipation of the thermal energy through the tissue and the amount of hyalinized collagen is higher in comparison to cold burns.…”