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Year : 2022  |  Volume : 13  |  Issue : 2  |  Page : 61-66

Analysis of Therapy by Means of Gallium Aluminum Arsenide Laser During Orthodontic Tooth Movement: A Randomized, Split Mouth Controlled Clinical Trial

Department of General Surgery and Surgical-Medical Specialties, School of Dentistry, University of Catania, Catania, Italy

Date of Submission25-Nov-2020
Date of Decision28-Feb-2021
Date of Acceptance29-Apr-2021
Date of Web Publication12-Jul-2022

Correspondence Address:
DDS, PhD Gaetano Isola
Pg. Oral Surg, Senior Assistant Professor, School of Dentistry, Department of General Surgery and Surgical-Medical Specialties, University of Catania, Via S. Sofia 78, Catania, 95124
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/denthyp.denthyp_48_21

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Indroduction: Preliminary evidence have shown that low intensity laser therapy is able to increase the rate of tooth movement. The aim of this study was to analyze the effects of gallium aluminum arsenide (GaAlAs) laser therapy in the enhancement of speed of orthodontic tooth movement (OTM) in a clinical protocol. Materials and Methods: Thirty-six upper canines were analyzed on 18 enrolled patients. On all experimental canine, an orthodontic force of 40 g/side was applied by a nickel-titanium closed coil spring. Using a split mouth randomized design, the test side was treated using a diode laser operating at a wavelength of 780 nm in continuous wave mode with flattop handpiece (20 mW output power, dose of 5 J/cm2, and exposure time of 10 seconds) (test side) at baseline and at 7, 14, and 28 days and every 14 days until the space closure. On the control side, selected teeth were only tractionated. The primary outcome was the overall time needed to complete leveling and closing space, measured on study cast. The secondary outcome was the evaluation of pain levels related to tooth traction, evaluated using a visual analogue scale (VAS). Results: The test side showed a significant reduced overall time needed for tooth space closure (at 7 and 14 days) and less VAS score (P < 0.001) compared to control side. Conclusion: This study shows that the use of low-level laser therapy by means of GaAlAs laser was effective for accelerating tooth movement and reducing pain levels related to OTM.

Keywords: Diode laser, pain, photobiomodulation, split mouth study, tooth movement

How to cite this article:
Giudice AL, Palazzo G, Campagna P, Fichera G, Isola G. Analysis of Therapy by Means of Gallium Aluminum Arsenide Laser During Orthodontic Tooth Movement: A Randomized, Split Mouth Controlled Clinical Trial. Dent Hypotheses 2022;13:61-6

How to cite this URL:
Giudice AL, Palazzo G, Campagna P, Fichera G, Isola G. Analysis of Therapy by Means of Gallium Aluminum Arsenide Laser During Orthodontic Tooth Movement: A Randomized, Split Mouth Controlled Clinical Trial. Dent Hypotheses [serial online] 2022 [cited 2022 Aug 8];13:61-6. Available from:

  Introduction Top

The orthodontic tooth movement (OTM) presents three distinct phases: one of initial tissue deformation, an intermediate delay phase, and a final progressive movement of the force.[1] The initial tooth displacement, equal to 0.4 to 0.9 mm, usually takes place within a week and is due to the progressive deformation of the periodontal ligament, the alveolar bone, and the dental extrusion.[1],[2] However, the initial displacement due to orthodontic force determines, especially in the early stages, a strong increase in stress in the periodontal ligament for the appearance of an osteogenic response responsible for the subsequent bone remodeling.[3]

This stress, which accumulates over time in the periodontal apparatus, can result in a significant reduction in the speed of the tooth movement and in the relative orthodontic treatment length, a condition that sometimes determines the success of the treatment.[4] In addition, an orthodontic treatment that lasts over time causes disorders such as gingivitis, root resorption, and possible dental ankylosis as well as blemishes.[5] Therefore, alternative and minimally invasive therapies and methods are necessary to accelerate the physiological movement of the teeth without causing damage to the oral tissues.[5],[6] Among the possible agents for dental movement, the low-level laser therapy (LLLT) has been shown to be a valid method that sustains tooth movement by means of the photobiostimulation effect that would allow a greater speed of orthodontic movement.[6]

The use of LLLT in the orthodontic field has been shown to be useful and effective in tissue biostimulation with stimulating effects in tissue repair and dental displacement, as well as inhibiting the release of pain mediators related to analgesia.[7],[8] The tissue-stimulating effect induced by LLLT therapy is also due to the biological growth and metabolic changes of soft and hard oral tissues, which stimulates, in the long term, a better bone and tissue neoformation process which in turn determines a greater shift in the shortest time.[9]

The effect of biostimulation by LLLT therapy can be determined by a different variety of lasers currently on the market, including Nd:YAG, He-Ne, and diode lasers.[8],[9] Among these, the gallium aluminum arsenide (GaAlAs) semiconductor diode laser has been shown to be widely penetrating at the tissue level with reduced light absorbed by tissues. These actions allow this laser to accelerate the repair of mucosa and tissues and to determine a relatively low mechanical stress to the roots of the dental elements that are already subjected to orthodontic traction. Furthermore, the diode laser has been shown to have hemostatic, bactericidal, and detoxifying effects[9]; in fact, this laser is used in the clinical field for minor oral surgery, for periodontal therapy, and for the treatment of dentinal hypersensitivity.[10],[11]

The effect of GaAlAs laser therapy during orthodontic movement has not yet been fully understood, although its positive effects have been demonstrated in some experimental studies.[8] Therefore, the objective of the present study was to evaluate the effect of laser-induced biostimulation using a of GaAlAs semiconductor diode laser in accelerating OTM. Moreover, the secondary objective of the study was to evaluate the effectiveness of LLLT by means of GaAlAs on the pain experienced by the patient during OTM.

  Materials and Methods Top

Study design

Patients who needed an orthodontic treatment were enrolled for the present randomized, split mouth controlled clinical trial (RCT). This trial was performed in accordance with the CONSORT (Consolidated Standards of Reporting Trials) guidelines. Ethical approval was obtained before the trial (18/18 approved on March 07, 2018). Written informed consent was obtained from all participants.

Study sample

Patients who needed maxillary first premolar extraction and bilateral maxillary canine distalization were selected from September 2018 to November 2019 among those who attended at the School of Dentistry of the University of Catania, Catania, Italy.

The inclusion criteria were: (1) Patients who required for orthodontic purposes of the extraction of the first maxillary premolars due to excessive dental crowding or biprotrusion, (2) presence of permanent dentition, (3) absence of any systemic condition that could have influenced the results of the study, (4) previous orthodontic treatment, (5) previous history of trauma, and (6) past or present signs of periodontal disease.

In the first phase, 50 patients were enrolled. After a first screening, 32 patients were excluded from the final sample because they did not meet the inclusion criteria (n = 26) while declined to participate into the study (n = 6). Thus, for this study, 18 patients, 10 males and 8 females, matched by age and sex (mean age 12.9 years, range 10–19 years) were finally included.

Power sample analysis and randomization

The power sample was calculated with an effect size of 0.40, a = 0.050, and with a power level of 0.80 for the tooth movement, which was the primary variable chosen. Considering a standard deviation (SD) of 0.98 mm and a mean difference of 1 mm as clinically significant, the minimum sample calculated for analysis was estimated 15 dental elements per analysis group to be necessary. Considering expected dropouts, 18 elements per group were enrolled for the study.

All patients were assigned, using a simple randomization technique, in a 1:1 allocation ratio. Randomization was carried using a computerized random number generator. Each site was allocated to receive one of the two treatments (test and control) using random permuted blocks with a distribution masked in sequentially sealed and numbered envelopes. Then, each selected tooth was assigned to one of the two groups. Only one clinician not involved in the subsequent phases of the trial performed the random allocation sequence and assignment to intervention. For the study, a total of 36 maxillary canines were selected and evaluated, divided into two groups, that is, test (18 canines) and control side (18 canines) [Figure 1].
Figure 1 CONSORT flowchart.

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All patients underwent a fixed orthodontic treatment with metal brackets from 0.022 to 0.028 inch (Ormco Corp., Orange, CA, USA). After the initial alignment and leveling phase that requested approximately 6 months, a final stainless steel was placed.

Then, after 21 days the extractions of the first premolars were performed. Subsequently, 7 days after premolar extractions, stainless steel segmented arches of 0.016 × 0.022 were applied in association with closed nickel-titanium (NiTi) coil spring (9 mm in length, G&H, Franklin, IN, USA), which delivered a force of 40/g maximum extension applied on the buccal side [Figure 2]. The force exerted by the coil spring was measured by a commercial dynamometer (commercial brand Morelli). A subsequent and progressive reactivation of the spring was carried out every 21 days until the total closure of the extraction space.
Figure 2 The closed NiTi coil spring of 10 mm used for the study and activated with a force of 40 g. NiTi, nickel-titanium.

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In the test side, the deliver LLLT to the experimental canine was performed using a GaAlAs semiconductor diode laser (SL-3 Laser, DenMat, Lompoc, CA, USA), emitting infrared radiation at 780 nm, and operating in continuous wave mode with a cylindrical quartz tip of 4 mm2 surface. The laser device was applied in both buccal and palatal side starting from the center of the root. Each area was irradiated with an output power of 20 mW, dose of 5 J/cm2, and exposure time of 10 seconds on vestibular and palatal sides, the rest time was

30 seconds between each session, and the treatment was repeated three-time. Protective eyewear has been used to protect patients and operators throughout the irradiation time. Irradiation was performed following activation of the NiTi spring on the maxillary canines and repeated at baseline and 7, 14, and 28 days after the first application and every 15 days until the completion of the leveling and closure of the extraction space. Every 14 days after irradiation, the measurement of the dental displacement on both test and control sides was performed. The canine of the control side was subjected to distalization by using the coil spring only.


The primary outcome was the overall time needed to complete space closure of the maxillary canines, measured in millimeters. The tooth space closure was evaluated on the dental study cast obtained at baseline (T0), after 1 month of treatment (T1), after 2 months (T2), and at the end of the tooth distalization (T3).

The secondary outcome was the pain experienced by the patient during the tooth movement. At the baseline, each patient was asked to record the pain using a visual analogue scale (VAS).

The patients were carefully instructed regarding how to complete VAS for left and right sides. Patients were asked to fill their VAS score 7, 14, and 28 days after treatment. The score zero represented the absence of any pain/discomfort, while score 10 intended any pain considered intolerable. At 6 months after therapy, each patient was called for a dental routine examination which comprised a clinical and radiological analysis (using Rinn periapical X-Rays) for the evaluation of possible damage to soft and hard tissues or roots reabsorption of the treated tooth. At this stage, every possible complication at the dental, bone, and periodontal levels was recorded.

The inter-examiner reliability test was performed and resulted in an agreement of 86.5% (k = 0.69) for the primary outcome chosen. The intra-examiner agreement was evaluated by the Cohen's k coefficient that resulted in 0.814 and predicteda good degree of reliability. The kappa coefficient was also calculated for the measurements taken at each follow-up session, and an acceptable degree of reliability (ICC = 0.787) was established for every examination. To assess measurement reliability at T1, nine dental casts were randomly chosen, and LII measurements were repeated 1 month after the first ones.

Statistical analysis

All the numerical data were expressed by mean values ± SD, while the categorical variables were expressed as a number and a percentage. The data were normally distributed using the Kolmogorov-Smirnov test that revealed normal data distributions. The data were compared by two-sample t tests. For the analysis of differences in post-therapy pain levels, the Mann–Whitney test was used. All data were processed using SPSS 11 (SPSS Inc., Chicago, IL, USA). A significance value with P < 0.05 was chosen as statistically significant.

  Results Top

All participants completed successfully the study and all the follow-up sessions. [Table 1] and [Table 2] shows the average speed values in the test side (diode laser) and the control side. The laser group yielded less mean time (82.46 ± 11.28 days) to accomplish leveling and alignment compared to the control group (94.21 ± 11.39 days), with a mean reduction of 27% in the overall treatment time in test side compared to control side (P < 0.001) [Table 2].
Table 1 Demography, clinical characteristics, and descriptive statistics of the study sample.

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Table 2 Time to distalize upper canines using fixed appliance (control group) and fixed appliance plus laser therapy (laser group).

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[Figure 3] shows the average levels of VAS score at the different follow-up sessions on test and control sides. The test side (diode laser) showed a significant reduction in the average range of dental pain due to orthodontic traction at 7, 14, and 28 days after laser treatment (pP < 0.001) [Table 3]. At a further 6-month follow-up check, none of the patients enrolled presented clinical periodontal damage, such as signs of gingivitis or initial signs of root resorption.
Figure 3 The results of the pain levels experienced in diode laser and control groups at each follow-up session (7, 14, and 28 days). Error bars represent the ± SD. ∗, P < 0.001. SD, standard deviation.

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Table 3 Time to distalize upper canines using fixed appliance (control group) and fixed appliance plus laser therapy (laser group).

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This study analyzed the influence of LLLT therapy by means of the GaAlAs semiconductor diode laser in the increased speed of the OTM and possible patient discomfort associated with the early stages of OTM. The results showed that the test side in which the LLLT was used resulted ina significant acceleration in tooth leveling and alignment at 7 and 14 days anda 27% decrease in the overall treatment time compared to the control side.

The studies currently present in the literature have shown the influence of laser-assisted therapy on orthodontic movement of animals, highlighting that soft tissue and bone tissues treated with LLLT demonstrated an accelerated process of tissue repair and neoapplication with a consequent increase in speed of dental movement.[2] It has been shown by several studies that dental movement due to orthodontic force results in modeling and tissue remodeling activities modulated by some growth factors, from nutrition, bone metabolism diseases, periodontal disease, and some mediators such as interleukins-1ß and some enzymes that, within the periodontal apparatus, increase in response to the mechanical stress induced by the orthodontic force.[12],[13]

Several studies demonstrated that LLLT therapy is an effective tool for tissue repair and of post-surgery bone neo-formation using tissue biostimulation.[14] The effect of biostimulation induced by LLLT has been analyzed in several reports which have shown an increase in wound healing, bone repair, and fibroblast growth in the early healing phases after laser application.[14],[15] In a study on bone regeneration of palatal suture in the rat by Saito and Shimizu,[16] the potential for stimulation of bone regeneration by LLLT therapy has been analyzed. In their study, these authors concluded that continuous irradiation for 4 to 6 days positively influenced bone growth only in the first phase of 0 to 2 days, whereas in the subsequent healing phases, 4 to 6 days, LLLT therapy did not have any effect.[16]

The effects of tissue biostimulation induced by laser therapy by LLLT at the bone neo-apposition level have been shown to be directly proportional to the dose and time of therapy by LLLT.[17],[18] Some studies carried out in vivo and on cell cultures evidenced a greater regenerative effect, in patients with hematological disorders, by laser therapy.[19] However, the optimal dosing parameters and exposure time to LLLT still need to be precisely determined.[20],[21] Similarly, although the mechanisms responsible for the reduction of pain induced by LLLT during OTM are still unclear,[21] it has been shown that LLLT possesses neural and anti-inflammatory regenerative properties linked to the effect of the photobioactive action on cell differentiation and proliferation useful for pain control during OTM.[22],[23]

  Conclusion Top

In conclusion, the results of the present study suggest the positive effects of LLLT by means of diode laser for accelerating OTM and for reducing dental pain linked to OTM. However, further studies are needed to understand better the mechanisms induced by laser therapy at the tissue level and the clinical level. According to the results of the present study, the use of LLLT therapy is an effective tool for accelerating tooth movement and reducing pain levels related to OTM.

Financial support and sponsorship

Funds of the Department of General Surgery and Surgical- Medical Specialties, University of Catania.

Conflicts of interest

There are no conflicts of interest.

  References Top

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Shimizu N, Yamaguchi M, Goseki T, Shibata Y, Takiguchi H, Iwasawa T, Abiko Y. Inhibition of prostaglandin E2 and interleukin 1-beta production by low-power laser irradiation in stretched human periodontal ligament cells. J Dent Res 1995; 74:1382-8.  Back to cited text no. 21
Lo Giudice A, Nucera R, Leonardi R, Paiusco A, Baldoni M, Caccianiga G. A Comparative assessment of the efficiency of orthodontic treatment with and without photobiomodulation during mandibular decrowding in young subjects: a single-center, single-blind randomized controlled trial. Photobiomodul Photomed Laser Surg 2020; 38:272-9.  Back to cited text no. 22
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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3]


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