Effects Of Non-Invasive Low Level Laser Therapy, Low Intensity Pulsed Ultrasound Treatment And Their Combination On Orthodontic Tooth Movement

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Date
2015-12
Authors
Jawab Al-Azzawi, Mohammed Mahmood
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Publisher
Universiti Sains Malaysia
Abstract
Orthodontic treatment is a process of achieving appropriate functions and esthetics by the movement of a tooth through the application of an external physical force in order to obtain physiological tissue reactions around a tooth, while avoiding the side effects of an external force. However, long-term therapy for several years is required. Accordingly, faster tooth movement without harmful effect on periodontal tissue and alveolar bone has been an important issue of interest to orthodontists and patients. Recently with the development of science, there is high attention among orthodontists to investigate the non-invasive stimulating techniques to improve orthodontic treatment. Many researchers have shown that proper use of low level laser treatment (LLLT) in orthodontic clinic can accelerate treatment, reduce appointments, and provide superior results, but there is no established regimen that all LLLT users within orthodontics are agreeing to follow. The non-invasive lowintensity pulsed ultrasound (LIPUS) has also been used to stimulate bone fracture healing by improving osteogenesis, remodeling and angiogenesis. However, there are limited numbers of studies on LIPUS stimulation for orthodontic tooth movement. To the best of our knowledge, there is no other study comparing the effect of LLLT with LIPUS for orthodontic tooth movement, or comparing the stimulatory effect of the combination of LLLT with LIPUS for orthodontics. This research was aimed to study in vitro and in vivo effect of different low level laser regimes, low intensity pulsed ultrasound and the combination of both techniques on orthodontic tooth movement. For in vitro, Human fetal osteoblast cell line (hFOB) was cultured and divided into different groups; 1st group was treated with 940 nm LLLT (with power ranging between 100-300mW), 2nd group was treated with LIPUS, 3rd group was treated with combination of LLLT and LIPUS. The application of LLLT or LIPUS or combination of them was once a day for 7 days. For cell proliferation, MTT assay was used. Both alkaline phosphatase and osteocalcin activity assays were assessed for cell differentiation. RT-PCR was also performed to elucidate the osteoblasts gene expression for COL1A1, RUNX-2 and BSP. For in vivo, 6-week-old Sprague Dawley male rats were used. Orthodontic appliances were inserted. A force of 10g was applied to the molars to induce tooth movement. The rats were grouped into four groups. The 1st group was irradiated with LLLT, 2nd group was treated with LIPUS and a 3rd group was treated with combination of both LLLT and LIPUS. A 4th group was a control group. The LLLT and LIPUS were used to treat the area around the moving tooth once a day till 1, 3, 7, 14 and 21 days. To determine the amount of tooth movement, plaster models of the maxillae were made. The models were imaged and analysed. Histological examination was performed after staining with (haematoxylin and eosin) and (Alizarin red and Alcian blue) stain. RT-PCR was also performed to elucidate the gene expression of RANK, RANKL, OPG and RUNX-2 in the area of treatment. The results of in vitro showed that all treatment groups significantly increased rate in cell proliferation and differentiation compared to the control group. The LIPUS group and the 300 mW LLLT group significantly increased the amount of cell proliferation. By contrast, the combination groups showed significantly greater amount of cell differentiation and gene expression. The results of in vivo showed that the amount of tooth movement, the histological bone remodelling and the RT-PCR was significantly greater in the treatment groups than that in the control group. Among the treatment groups, the combination group was the highest and the LIPUS group was the lowest. The findings of this study suggest that LLLT and LIPUS can stimulate osteoblast cells for bone formation. Additionally, they facilitate the velocity of tooth movement and improve the quality of bone remodelling during orthodontic tooth movement especially when they are combined together.
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Keywords
Orthodontic treatment , achieving appropriate functions.
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