|Year : 2017 | Volume
| Issue : 2 | Page : 81-86
Effect of low-level laser therapy on orthodontic tooth movement
Gagan Deep Kochar1, Sanjay M Londhe2, Bensy Varghese3, Balakrishna Jayan4, Sarvaraj Kohli5, Virender Singh Kohli6
1 Gd Spl, 1200 MDC, India
2 Comdt and Command Dental Advisor (SC), CMDC (SC), India
3 CO & Cl Spl, MDC, India
4 Consultant, Department of Orthodontics and Dentofacial Orthopedics, Research and Referral Hospital, New Delhi, India
5 Assoc. Prof, Department of Orthodontics and Dentofacial Orthopedics, Hitkarini Dental College and Hospital, Jabalpur, Madhya Pradesh, India
6 Prof. and HOD, Department of Orthodontics and Dentofacial Orthopedics, Hitkarini Dental College and Hospital, Jabalpur, Madhya Pradesh, India
|Date of Submission||25-Oct-2016|
|Date of Acceptance||15-Feb-2017|
|Date of Web Publication||17-Apr-2017|
Gagan Deep Kochar
Source of Support: None, Conflict of Interest: None
Introduction: Prolonged orthodontic treatment duration is detrimental in terms of increased incidence of caries, root resorption, and reduced patient compliance. The aim of this randomized, clinical trial was to evaluate the effect of low-level laser therapy (LLLT) on the rate of orthodontic tooth movement (OTM) and pain control. Materials and Methods: This single-blind study included twenty participants requiring extraction of all first premolars. Randomly selected split-mouth design was used. One side was irradiated with 810 nm diode laser (dose of 5.0 J/cm2) at 10 points for 10 s. Irradiation was performed just after loading canine retraction forces and on days 3rd and 7th. Every 21st day, the force level of coil spring was adjusted, and LLLT protocol was repeated till retraction was complete. Measurements were recorded on study models to evaluate the rate of retraction. Results: Significant increase in OTM was observed on the side exposed to LLLT when compared to control side (P < 0.05). Statistically significant difference in pain perception was observed during first 2 days only between lased site and control site (P < 0.05). Conclusion: LLLT is a reliable tool for enhancing OTM and is effective in relieving pain at parameter settings and protocol used in this study.
Keywords: Low-level laser therapy, orthodontic tooth movement, pain perception
|How to cite this article:|
Kochar GD, Londhe SM, Varghese B, Jayan B, Kohli S, Kohli VS. Effect of low-level laser therapy on orthodontic tooth movement. J Indian Orthod Soc 2017;51:81-6
|How to cite this URL:|
Kochar GD, Londhe SM, Varghese B, Jayan B, Kohli S, Kohli VS. Effect of low-level laser therapy on orthodontic tooth movement. J Indian Orthod Soc [serial online] 2017 [cited 2019 Jan 19];51:81-6. Available from: http://www.jios.in/text.asp?2017/51/2/81/204607
| Introduction|| |
Biologically, the orthodontic tooth movement (OTM) is a result of periodontal tissues remodeling in response to the applied mechanical force. The use of light forces is advocated to prevent bone necrosis or root resorption. This prolongs the duration of orthodontic treatment. Longer treatment duration is detrimental in terms of increased incidence of caries, root resorption, and reduced patient compliance.
Various surgical, nonsurgical, and pharmacological methods have been proposed by researchers to enhance OTM which includes corticotomy, alveolar decortication, distraction, resonance vibration, ultrasound waves, electric current, local injection of prostaglandins, 1,25(OH)2D3 (active form of Vitamin D), parathyroid hormone, and osteocalcin. Surgical methods have an inherent limitation of being invasive whereas pharmacological methods are not much popular as they result in pain at the site of injection and have systemic effects. Low-level laser therapy (LLLT) has gained popularity among researchers for enhancing OTM. It has advantages over other methods in terms of being noninvasive, ease of use, and localized action.
Studies have shown that LLLT increases osteoblastic activity, vascularization, and organization of collagen fibers. Researchers suggest that LLLT may enhance OTM in humans,, whereas many studies have shown no significant increase in the rate of OTM after LLLT., Some studies have even concluded that exposure to LLLT decreases OTM.
Although various articles are available in literature in which effect of LLLT on OTM has been evaluated, till date researchers believe that data pertaining to it are controversial and questionable., Recent systematic reviews have concluded that there is a lack of evidence regarding LLLTs effectiveness in accelerating OTM because of varying results shown by researchers. This disagreement among researchers may be due to varying laser attributes used in each study, i.e., laser type, method of application, wavelength, dose and exposure time as these parameters relate directly to laser clinical results., Hence, they have proposed that more studies with similar laser parameters should be carried out. To bridge this gap of knowledge, the present study was undertaken with an aim to evaluate the effect of LLLT on OTM and pain perception.
| Materials and Methods|| |
Twenty patients (12 males, 8 females, 16–24 years) diagnosed with dental Class I bimaxillary protrusion with no significant medical history requiring extraction of all first premolars for orthodontic management were selected for the study. None of the patients had crowding of more than 3 mm. Patients on medications such as long-term nonsteroidal anti-inflammatory, bisphosphonates, hormone supplements, patient with poor periodontal health, dilacerated or impacted tooth, and pregnant females were excluded from the present study as these factors may interfere with normal OTM.
A split-mouth design was used to rule out biological variations. One side in each patient was exposed to LLLT, and it was labeled Group A whereas other side did not receive any LLLT exposure and was labeled Group B. Patients were blinded for exposed and unexposed side.
The research proposal was approved by the Institutional Research Ethics Committee, and informed consent was obtained from all participants.
Full-arch strap up was done using 0.018-inch slot Roth brackets in all the cases. In maxilla-soldered Nance button and in mandible soldered lingual arch was cemented using glass ionomer cement. First premolars of all the four quadrants were extracted, and leveling and alignment was carried out. The working archwire was 0.016-inch stainless steel. Canines were ligated to working archwire using 0.01-inch stainless steel ligatures. Three weeks after the insertion of working, archwire canine retraction was initiated using nickel–titanium (Ni-Ti) closed-coil spring (Ormco, Sybron Dental Specialities Inc., Newport Beach, CA, USA).
Spring was attached to molar tube hook of first molar and power arm of canine bracket to deliver the retraction force of 150 g, which was measured using dynamometer. Force level was evaluated and maintained by periodic recall once every 21 days till retraction of canines was complete.
An infrared spectrum (810 nm wavelength) continuous wave of semiconductor diode aluminum-gallium-arsenide laser (Thera Laser, DMC, Sao Carlos, SP, Brazil) with irradiation area 0.4 cm 2 was used for irradiation.
The LLLT application was performed by one operator with an output power of 100 mW, dose of 5.0 J/cm 2, and exposure time of 10 s. The tip of the probe was placed perpendicular to the tissue gently without pressure [Figure 1]. Cervical, an apical third of canine root, was exposed mesially and distally, and the middle third was exposed in the center on the buccal and palatal side making a total of 10 exposures during each visit. For blinding purpose, the tip of the handpiece was held on the control side, but no LLLT exposure was given.
Irradiation was performed immediately after canine retraction forces were applied and on days 3rd and 7th. Every 21st day, the force level of coil spring was adjusted, and LLLT protocol was repeated till retraction was complete. Safety measures for the participants and the operator were followed. Periapical radiographs were recorded after 3 months and on completion of retraction to check the status of periodontal structures.
To record canine movement, four pairs of casts were made for each patient, i.e., at the onset of canine retraction (C1), 2 months after retraction initiation (C2), 4 months after retraction initiation (C3), and on completion of canine retraction (C4). The distance between mesial cusp tip of the first molar and cusp tip of canine for both the exposed and unexposed side in maxillary as well as mandibular arch was recorded in millimeters using caliper in all the models. The rate of canine retraction was determined by dividing distance traveled with time elapsed. Measurement of C2 and C1 was used to determine the rate of retraction in 2 months (T1). Similarly, C3–C1 gave a rate of retraction in 4 months (T2), and C4–C1 gave a rate of retraction on completion (T3). All measurements were recorded by same person. He/she was blinded for control and lased site.
To access pain, 100 mm visual analog scale was used. Patients were instructed to mark their pain level in a scale with 0 representing no pain and 100 representing severe pain. They were instructed to record pain level after 6 h, 24 h, and on day 2nd till the 7th day.
The collected data were compiled in a Microsoft Excel worksheet. Data were analyzed using SPSS version 18.0 software (SPSS Inc., Chicago, IL, USA). To assess intrainvestigator error, models of eight patients were remeasured 2 weeks after the first evaluations. An intrainvestigator reliability test to measure method error was conducted using Cronbach's alpha value.
Mean and standard deviation were calculated. The T1, T2, and T3 measurements were compared with paired samples t-tests. P < 0.05 was considered statistically significant [Table 1],[Table 2],[Table 3].
|Table 1: Comparison of rate of canine retraction between Group A and Group B|
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|Table 2: Comparison of rate of canine retraction between maxillary and mandibular Group A|
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|Table 3: Comparison of rate of canine retraction between maxillary and mandibular Group B|
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Wilcoxon's signed-rank test was done to study the differences in pain levels between the lased and control groups.
| Results|| |
In the present study, no difference in values was found for patient age or sex (P > 0.05). The data were equally distributed. Cronbach's alpha ranged from 0.83 to 0.87 demonstrating high reliability between measurements taken 2 weeks apart. The mean age of the sample was 19.69 ± 1.40 years. The results of the paired samples t-tests for the comparison of the rate of canine retraction between Group A and Group B after 2 months, 4 months, and on completion of retraction are shown in [Table 1]. Highly significant difference was observed between site exposed to LLLT and control site (P < 0.05). In maxillary arch, rate of retraction after 2 months was 1.13 ± 0.13, after 4 months was 1.86 ± 0.36, and on completion was 1.92 ± 0.16 in Group A, whereas Group B demonstrated retraction rate of 0.86 ± 0.017, 0.92 ± 0.023, and 0.94 ± 0.014, respectively. In mandibular arch, rate of retraction after 2 months was 1.04 ± 0.33, after 4 months was 1.49 ± 0.27, and on completion was 1.63 ± 0.23 in Group A, whereas Group B demonstrated retraction rate of 0.79 ± 0.24, 0.88 ± 0.12, and 0.92 ± 0.14, respectively.
The results of the paired sample t-tests for the comparison of rate of canine retraction between maxilla and mandible on lased side are depicted in [Table 2]. Statistically significant difference was seen between them (P < 0.0.5).
The results of the paired samples t-tests for the comparison of the rate of canine retraction between maxilla and mandible on control side are shown in [Table 3]. Statistically significant difference was not seen between them (P < 0.0.5).
Statistically significant difference in pain perception was observed till the 2nd day between lased and control site (P < 0.05) [Table 4] and [Graph 1]. From the 3rd day till 7th day, no statistically significant difference in pain perception was recorded in the present study.
|Table 4: Comparison of pain score between Group A and Group B using visual analog scale|
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| Discussion|| |
Over recent years, photobiomodulation also referred to as LLLT has gained popularity among researchers for accelerating OTM and relieving pain. It has been proposed that biomodulating the effect of lasers is related to its ability to accelerate the cell metabolic alterations which in turn stimulating bone remodeling. Studies in literature have used varying degree of wavelength to determine the effect of LLLT on OTM. Fujita et al. and Yoshida et al. used 810 nm, whereas AlSayed Hasan et al. used 830 nm and Gama et al. used 790 nm. These studies have shown conflicting findings. In our study, we used laser of 810 nm wavelength.
Sousa et al. used continuous wave laser whereas Yoshida et al. proposed that pulsed radiation is a better method of light delivery. In the present study, the continuous mode was used to study the effect of LLLT.
Our study was a prospective blind study as patients did not know which side received laser exposure. A split-mouth design was used to rule out biological variations.
Biomodulatory effects of laser are based on Arndt–Schulz law. According to this law, a small dose of any substance/drug has a stimulating effect, whereas higher dose is inhibitory. In our study, 5.0 J/cm 2 of energy was applied. It is similar to the protocol used by Sousa et al. In the present study, we observed that total time required for canine retraction on lased site was 67% lesser than the time required on control site. There was about 1.7 folds increase in retraction rate. Sousa et al. demonstrated similar results. They found 2 folds increase on lased side. Youssef et al. applied 8.0 J/cm 2 and found 2 folds increase in the rate of retraction. AlSayed Hasan et al. demonstrated increased in OTM by applying 2.25 J/cm 2. However, our results are not in agreement with those of Limpanichkul et al. They applied 25 J/cm 2 and observed no significant difference between the experimental and the control group. Difference in results may be due to difference in energy applied.
In our study, we observed that the rate of retraction on lased side increased with time. Mean rate of retraction of 1.13 at T1 got increased to 1.92 at T3 in the maxillary region, whereas in the mandibular region, it increased from 1.04 at T1 to 1.63 at T3. Studies are available in literature which has shown opposite results. Dalaie et al. in their study found no significant difference in OTM between controlled and lased side.
Our study compared the rate of retraction in maxilla to that of the mandible. No difference was observed on the control side whereas OTM was much rapid in maxilla as compared to mandible on the side exposed to laser. It is believed that such a difference may be due to the difference in bone densities as the laser has to stimulate deep-rooted bone cells and periodontal ligament cells.
There are no effective clinically proven noninvasive, nonpharmacological methods used to relieve the pain caused by orthodontic treatment. Although some researchers believe that LLLT can effectively reduce the orthodontic pain, results are inconclusive till date. This gap in knowledge has been investigated in our study. Bjordal et al. compared the analgesic effect of lasers with nonsteroidal anti-inflammatory drugs and found results to be equivocal. Dalaie et al. in their study found no significant difference in pain perception between controlled and lased side. As per available literature, laser dose over 20 J/cm 2 shows inhibitory action. To study the effect of LLLT on pain, we used dose of 5 J/cm 2.
In the present study, VAS scale was used to analyze the effect of laser on pain perception. As per current literature, this is a reliable tool for such studies.
In our study, we observed that difference in pain perception was significant till 2nd day. A similar result was shown by Eslamian et al. They observed the statistically significant difference between lased and control side till 3rd day only, whereas Youssef et al. and Doshi-Mehta et al. observed statistically significant difference during entire retraction phase.
Karu  proposed that cellular response to laser is enhanced when redox potential of cell is low, whereas it is diminished when potential is normal. Since microtrauma is induced during orthodontic treatment, so redox potential is low at the cellular level. It may be one of the reasons responsible for enhanced OTM and analgesic action postlaser exposure.
Radiographs taken at regular intervals demonstrated no detrimental changes to periodontal structures.
Although in the present study LLLT has shown promising results in terms of enhancing OTM and relieving pain, its limitations cannot be negated. The cost of the equipment and increased frequency of patient visit should always be considered.
Although numerous animal and humans studies have been carried out to determine the effect of LLLT on OTM, their results are conflicting. There is a need to carry out more studies with the rigorous design so that a standard LLLT protocol can be formulated.
LLLT is a reliable tool for enhancing OTM during retraction phase with no detrimental effect on periodontal tissues. Parameter settings and protocol used in the present study have shown promising results in terms of reduced treatment time. LLLT has an analgesic effect, but it is significant only during the first 2 days of activation of retraction force.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]