Effects of different settings for 940 nm diode laser on expanded suture in rats

Abstract

Objectives: To evaluate the effects of the Indium Gallium Arsenide Phosphoride (InGaAsP) diode laser at different energy levels on orthopedically expanded midpalatal sutures of rats. Materials and Methods: Eighty Wistar rats were randomly divided into four groups: a control group and low-, moderate-, and high-level laser groups with amounts of energy irradiated at 0 J, 18 J, 42 J, and 60 J, respectively. Each group was divided into two subgroups (n = 10) according to the schedule of sacrifice (7 and 21 days). Laser application (940 ± 10 nm, 0.1 W) was completed twice weekly until sacrifice. The number of osteoblasts (OB), osteocytes (OC), and vessels (V); area of connective tissue (CT); inflammation (IN); and newly formed bone (NB); as well as the ratio of newly formed bone to the total bone area (N/T) were evaluated statistically at a significance level of P < .05. Results: For the low-level laser group, OB, NB, and N/T were significantly higher, and CT was lower, on both the 7th and 21st days. The amount of OC was significantly higher in the low-level laser group compared with the control group on the 7th day and the control and high-level laser groups on the 21st day. The IN was significantly higher for the high-level group on the 21st day compared with other groups. Both the moderate-level and high-level laser groups possessed fewer vessels than the low-level laser group on the 21st day. Conclusions: The InGaAsP laser at the low dosage induced a favorable effect on bone formation in the orthopedically expanded midpalatal suture of rats.

Effect of salvianolic acid B on new bone formation in the orthopedically expanded suture:

“…As previously reported, an expansion spring fixed to the upper incisors was used to expand the premaxilla in rats. 5,6 Mid-palatal separation in rats was reported to be achieved with only 50 to 70 g force. 5 Thus, in this study, all sutures were expanded with 70 g force.…”

“…4 More rapid formation of new bone in the expanded mid-palatal suture may be useful to shorten the retention period and there is also evidence that this may inhibit relapse of the skeletal transverse expansion. Purposefully, practitioners have worked on the acceleration of new bone formation using different methods such as laser stimulation 5 and the use of agents including transforming growth factor, 6 bisphosphonates, 7 antioxidants, 8 and lactoferrin. 9 More recently, researchers have studied antioxidants more closely due to their stimulatory effect on bone metabolism via osteoblastic stimulation.…”

Benefits of Using Low-level Laser Therapy in the Rapid Maxillary Expansion: A Systematic Review

“…In addition, it is reported that lower levels of stimuli increase physiological functions, while high-intensity stimulation can decrease and even inhibit them. 16 The results obtained by Tas Deynek and Ramoglu 10 confirms the theory of the therapeutic window, where the authors observed that the best reparative effects on rats were obtained at a lower dose (18 J/cm 2 ), with a higher initial concentration of osteocytes, subsequent increase of osteoblasts, blood vessels, and new bone tissue. By contrast, groups who received higher doses of radiation showed increased inflammation and decreased regeneration.…”

“…Although it has been shown that the use of a lower-power laser improves bone regeneration results, there is still no consensus regarding the dose needed to obtain the desired results. According to the law of Arndt-Schultz, 10 , 16 there is a therapeutic window of the effective dose range, due to the different stimulus intensities, they can increase or decrease physiological functions. In addition, it is reported that lower levels of stimuli increase physiological functions, while high-intensity stimulation can decrease and even inhibit them.…”

“…Currently, low-level laser therapy (LLLT) techniques have been applied to soft tissues 2 as a complement to other treatments, because it is a noninvasive technique that—with the application of low light energy—acts as a cellular “photo-modulator”, 1 , 8 stimulating cell proliferation, 9 bone healing, and regeneration. 3 , 5 , 8 , 10 , 11 …”