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The aim of this study was to evaluate the canine retraction rate for two low intensity laser therapy (LLLT) irradiation regimens, including high and low frequencies. Twenty patients were randomly divided into two groups. In group A, one side of the maxillary arch was randomized to receive LILT on days 0, 3, 7, 14, and every 2 weeks thereafter, while in group B, one side received LILT every 3 weeks. During the 12-week study period, tooth mobility was checked every three weeks from the start of canine retraction. In addition, the levels of interleukin-1β (IL-1β) in the gingival sulcus fluid were assessed. Results revealed a significant increase in the canine retraction rate on the laser sides of groups A and B, in comparison with the control sides (p < 0.05), with no significant differences reported between the laser sides in both groups (p = 0.08–0.55). Results revealed a significant increase in the canine retraction rate on the laser sides of groups A and B, in comparison with the control sides (p < 0.05), with no significant differences reported between the laser sides in both groups (p = 0.08–0.55 ). Результаты выявили значительное увеличение скорости ретракции клыков на стороне лазера в группах A и B по сравнению с контрольной стороной (p < 0,05), без существенных различий между сторонами лазера в обеих группах (p = 0,08–0,55). The results revealed a significant increase in canine retraction speed on the laser side in groups A and B compared to the control side (p < 0.05), with no significant difference between the laser sides in both groups (p = 0.08–0.55). ).结果显示，与对照组相比，A 组和B 组激光侧的犬齿回缩率显着增加（p < 0.05），两组激光侧之间无显着差异（p = 0.08-0.55 ）。结果 显示 ， 与 对照组 ， 组和 a 组和 b 组 激光侧 犬齿 回 缩率 显着 （（p <0.05） 两 组 激光侧 之间 显着 差异 （p = 0.08-0.55。。。。。。。 Результаты показали, что по сравнению с контрольной группой скорость ретракции клыков на стороне лазера в группах А и В была значительно выше (p < 0,05), а на стороне лазера не было существенной разницы между двумя группами (p = 0,08-0,55). The results showed that, compared with the control group, the canine retraction rate on the laser side in groups A and B was significantly higher (p < 0.05), and there was no significant difference between the two groups on the laser side (p = 0.08-0 .55). Also, IL-1β levels were significantly higher on the laser sides of both groups, in comparison with the control sides (p < 0.05). Also, IL-1β levels were significantly higher on the laser sides of both groups, in comparison with the control sides (p < 0.05). Кроме того, уровни IL-1β были значительно выше на стороне лазера в обеих группах по сравнению с контрольной стороной (p < 0,05). In addition, IL-1β levels were significantly higher on the laser side in both groups compared to the control side (p < 0.05).此外，与对照组相比，两组激光侧的IL-1β 水平显着升高（p < 0.05）。此外，与对照组相比，两组激光侧的IL-1β 水平显着升高（p <0.05）。 Кроме того, уровни IL-1β были значительно повышены на стороне лазера в обеих группах по сравнению с контрольной группой (p < 0,05). In addition, IL-1β levels were significantly elevated on the laser side in both groups compared to the control group (p < 0.05). Thus, LILI was able to effectively accelerate tooth movement, whether it was used frequently or rarely, which was associated with an increased biological response, which was reflected in increased levels of IL-1β on the compressed side.
Long-term orthodontic treatment (typically around 20–30 months1) has been found to negatively impact patient compliance, in addition to risks such as root resorption2, caries3, enamel decalcification3 and periodontal problems4,5. Therefore, several methods have been proposed aimed at accelerating orthodontic tooth movement (OTM), including surgical and non-surgical care. In addition, the effect of combining two acceleration methods and the effect of repeating the same acceleration process on the speed of OTM6 was investigated.
Low intensity laser therapy (LLLT) has been one of the proposed non-surgical approaches to accelerate OTM, but there have been conflicting results in reports of its effectiveness in this area, while positive7,8 and negative9 effects have been documented. These conflicting results can be explained by differences in the laser application parameters used in each study, including laser type, method of application, wavelength, radiation dose, and exposure time, since these parameters are directly related to the clinical results of laser application 10.
In terms of application methods, various laser irradiation protocols have been reported to facilitate tooth movement. One widely used protocol involves applying the laser on days 0, 3, 7, 14, 21 and 30, repeating the same sequence every month, and this protocol has been adopted by several authors11,12. Others have used an alternative regimen that is relatively close to the previously described regimen and is also one of the widely used approaches, in which LILI is applied on days 0, 3, 7, 14, and then every 15 days until the end of the study period. 13. In addition, a protocol has been proposed that includes weekly application of a low-intensity laser throughout the canine retraction period. However, the main disadvantage of these conventional protocols is the high rate of patient feedback, which can be inconvenient for everyone. Thus, protocols that require fewer patient referrals are used, for example, including LILI 8 times a month or 15, 16, 17, 18 every 3 weeks.
Since orthodontic forces are known to cause bone remodeling, the development of inflammatory changes is a prerequisite for this process, leading to misalignment of teeth19. According to several studies, one way to assess potential biological events in the periodontal ligament is to assess the level of cytokines in the gingival sulcus fluid (GCF). Interleukin-1β (IL-1β) is a very active cytokine in bone metabolism and is considered one of the most potent cytokines in early OTM periodontal tissue. Since there is a correlation between IL-1β levels and survival, fusion and osteoclast activation, IL-1β can be considered as an important marker for calculating the degree of orthodontic tooth movement, which is related to the efficiency of alveolar bone remodeling24.
Therefore, the aim of our study was to evaluate and compare the effects of NILT with commonly used regimens, including a high frequency of use on days 0, 3, 7, 14, and then every 2 weeks compared with use every 3 weeks. Retraction rate in dogs in an attempt to reduce the frequency of patient recalls. In addition, IL-1β levels in GCF were assessed using two protocols. The null hypothesis of the current study is that there is no difference in the incidence of canine retraction with LILI using the two testing protocols.
The study was a randomized controlled clinical trial with two parallel groups, each testing a LILI protocol. Each group adopts the split mouth design, one side is the control group and the other is the study group.
The study included 20 patients aged 15 to 20 years who needed therapeutic removal of the first premolars of the upper jaw, followed by retraction of the canines. Sample size calculations were based on an alpha error of 5% and study power of 80%. This calculation is based on the mean and standard deviation of canine retraction in studies in which Doshi-Mehta and Bhad-Patil7 applied LILI on days 0, 3, 7, 14 and every 2 weeks thereafter (Arm A) and in the Qamruddin studies et al. others In 15 studies, LILI was applied every 3 weeks (group B). Ethical approval was obtained from the Ethics Council of the Faculty of Dentistry, Alexandria University, Alexandria, Egypt (IRB: 00010556-IORG: 0008839). The number of the manuscript ethics committee is 0111-01/2020. Approved January 21, 2020. The trial is registered with ClinicalTrials.gov as “Two Low Level Laser Protocols to Evaluate Retraction Velocity in Dogs.” The trial registration number is NCT04926389. Trial registration date is 06/15/2021 at https://clinicaltrials.gov/ct2/show/NCT04926389. The enrollment of patients in the study began on February 5, 2020 and ended on November 28, 2021.
Patients were recruited from the orthodontic clinic of the Faculty of Dentistry of Alexandria University. Subjects were screened and assessed against the following eligibility criteria: general health, absence of chronic disease, no previous orthodontic treatment, adequate oral hygiene, and healthy periodontal tissues. The participating patients and their parents were provided with a full and detailed explanation of the study procedures, and therefore, informed consent was obtained from each included subject. All research procedures were carried out in accordance with the relevant guidelines and rules set out in the Declaration of Helsinki.
Before starting canine retraction, 20 patients were selected and randomly assigned to group A or group B (10 in each group) for low-intensity laser therapy. Randomization was performed using a simple randomization process with a distribution ratio of 1:1. A box was prepared containing twenty folded sheets of paper, ten of which were inscribed with the words “Group A” and the other ten with the words “Group B”. Each participant was asked to choose a folded piece of paper from a box and assign it to one of two groups accordingly. The same procedure was repeated again in each group, designating one side of the maxillary arch as “test” and the opposite side as “control” in a split-mouth design.
In addition to the usual orthodontic records (intraoral and extraoral photographs, radiographs, and dental impressions), subjects prepared for fixed orthodontic treatment were enrolled by compiling their medical and dental histories. Patients were also asked to perform a complete oral cleaning and polishing followed by instruction in proper oral hygiene (use of toothbrush, floss and interdental brushes).
Maxillary and mandibular fixation with straight wire Roth appliances (Mini 2000; Ormco, USA) with 0.022″\(\x)0.028″ slots were fixed in all recruited patients, where the fixation procedure was standardized for both groups and determined by the same operator. . Subsequently, the patient was referred for extraction of a maxillary first premolar to allow sufficient time for the socket to heal after extraction before starting extraction approximately 2 months after extraction. Alignment then begins and alignment is complete when a 0.016″ x 0.022″ stainless steel wire can be passively inserted into all maxillary teeth.
Before starting canine retraction, the upper second premolars and first molars were ligated together with a 0.009-inch figure-eight wire on the experimental and control sides of both groups. In addition, the maxillary incisors are tied together in the same way as the posterior segment to help stabilize and prevent their potential separation.
Canine retraction in groups A and B was performed using nickel-titanium (NiTi) closed coil springs (Ormco, USA), both on the experimental and control sides, stretched between the hooks of the canine brackets and the hooks on the molar canal, with a force of 150 g is measured dynamometer (Morelli, Brazil).
A diode laser (Wiser; Doctor Smile-Lambda Spa, Brendol, Italy) was used as a low-intensity laser, emitting infrared radiation with a wavelength of 980 nm and an output power of 100 mW in continuous mode. A plane wave fiber (AB 2799; Doctor Smile-Lambda Spa, Brendola, Italy) was used to distribute a 1 cm2 beam spot with a flat top tip, positioning the fiber tip along the maxillary arch in the middle third of the maxilla. canine root on the experimental side (according to the manufacturer’s instructions, a minimum of 1.5 cm when out of focus) for 8 seconds (Fig. 1). The total energy density applied per episode was 8 J/cm2 (1 J/cm2 per second). The laser parameters used are shown in Table 1. Precautions were taken before using the laser, and both the patient and the operator used goggles provided by the manufacturer, depending on the wavelength used.
The fiber tip was held at a distance of 1.5 cm from the root of the maxillary canine on the experimental side according to the manufacturer’s instructions.
The split-mouth technique was used in both groups, and each participant was randomized to receive LILI on one side of the maxillary arch and on the opposite side as controls. In group A, subjects received LILT on days 0, 3, 7, 14 and then every 2 weeks, while in group B it was applied every 3 weeks on the experimental side for the entire study period (12 weeks) of LILT. The laser beam was also passively fixed on the control side of both groups, providing a placebo effect as part of the process of blinding enrolled patients. Due to the nature of the intervention at this stage, the operator cannot be deceived.
Prior to specimen collection, both sides of the maxillary canines were cleaned with cotton swabs, isolated with self-supporting retractors, suction, and cotton rolls, and then gently air-dried for 5 s. Samples were taken from the distal clefts of the maxillary canines using standard filter paper strips (Whatman, Maidstone, UK) and cut into standard sizes of 2 × 10 mm2. Gently insert each strip into the gap until you feel a slight resistance, then leave it in place for 60 seconds while maintaining proper sealing (Figure 2). After removal, new strips were placed every 1 min to obtain 4 strips at each location. Measures were also taken to avoid mechanical damage to the gingival fissure. Dispose of samples contaminated with saliva or blood and collect new samples. GCF samples were taken at baseline (before the onset of canine retraction), from the distal canine fissures in groups A and B, on the experimental and control sides, except for days 7, 14, and 21.
Alginate impressions (Ca37; Cavex, Haarlem, The Netherlands) were performed prior to canine retraction and were repeated every 3 weeks during the 12-week study at each visit. At each visit, the wire and coil springs were removed, an alginate impression was taken, and the calculus was cast. The tooth model is then trimmed and marked with the patient’s name, number and date. The plaster model was then scanned (inEos X5 CAD/CAM laboratory scanner; Dentsply Sirona, PA, USA) to create a three-dimensional (3D) digital image of the tooth model. The necessary measurements were made using AutoCAD version 2013 (AutoCAD; Autodesk, USA). Clinicians were unaware of the experimental and control sides at the time of measurements to avoid unreasonable bias, and an intra-investigator reliability check was performed with repeated measurements by the same operator a week later to check for measurement errors. The estimated measurement error is 6%.
Several landmarks were found on the dental cast, including the median palatal suture, the medialmost points of the left and right third folds, and the cusps of the left and right maxillary canines. The vertical line runs from the medial points of the left and right third folds and tubercles of the left and right maxillary canines to the median palatine suture. Anterior-posterior measurements were taken between the bilateral canine line and the third fold line to assess canine retraction (Figs. 3, 4).
Locate landmarks on scanned images of tooth models to measure canine retraction. (One). Middle palatal suture. (b, d). Tubercles of the left and right maxillary canines, respectively. (c, e). Lines corresponding to the inner ends of the third left and right folds, respectively.
After removal from the gingival crevice, groups of four filter paper strips collected in one place were placed in Eppendorf tubes (Capp, Denmark) containing 100 µl of phosphate-buffered saline. Eppendorf tubes were sealed and labeled and the samples were immediately centrifuged at 3000 rpm for 10 min using a centrifuge (Hettich Universal 320R BC-HTX320; GMI, MN, USA) to recover the GCF samples from the strips. Eppendorf tubes were stored at -20°C until biochemical analysis. Analysis of IL-1β levels was performed using an enzyme-linked immunosorbent assay (ELISA; Cloud-Clone, Howe, USA). The concentration of IL-1β was determined by comparing the optical density (OD) of the obtained samples with the standard curve and accordingly calculated the equation of linear regression of the standard curve. Finally, the results for IL-1β levels are presented in pg/ml/60 s25. A flowchart of the study design is shown in Figure 5, which summarizes the study procedure.
Statistical analysis was performed using IBM SPSS for Windows version 23.0 (IBM; Armonk, NY, USA). All quantitative variables were normally distributed and mean, standard deviation (SD) and 95% confidence interval (CI) were calculated and parametric tests were used. Quantitative variables (canine retraction and IL-1β level) were compared between the two study groups using independent sample t-tests, while comparisons between laser and control sides in each group were performed using paired t-tests. Dog retraction and IL-1β levels at different times in each group were compared separately using repeated measures analysis of variance followed by multiple pairwise comparison using Bonferroni-adjusted significance levels. Significance was set at p value < 0.05. Significance was set at p value < 0.05. Значимость была установлена ​​при значении p <0,05. Significance was set at p value < 0.05.显着性设定为p 值< 0.05。显着性设定为p值< 0.05。 Значимость была установлена ​​на уровне p <0,05. Significance was set at p<0.05.
During the course of the study, no subject dropped out either during the pre-intervention period or during the remainder of the study. All 20 initially recruited subjects completed the entire 12-week study period (10 subjects per group). The patient flow for the entire trial is shown in Figure 6 using the CONSORT flowchart. Demographic data for subjects enrolled in Groups A and B are presented in Table 2. There were no cases of prolapse in the study models, which were performed every three weeks to measure canine retraction. In addition, all received GCM samples were carefully processed and analyzed.
The amount of maxillary canine retraction at the different time points is described in Table 3, regarding both groups A and B. In Group A, the greatest mean distance (± SD) travelled by the maxillary canine has been reported at the 3rd week to be 1.18 (± 0.04) mm on the laser side, and 0.85 (± 0.04) mm on the control side, with the difference between them being statistically significant (p < 0.001). The amount of maxillary canine retraction at the different time points is described in Table 3, regarding both groups A and B. In Group A, the greatest mean distance (± SD) travelled by the maxillary canine has been reported at the 3rd week to be 1.18 (± 0.04) mm on the laser side, and 0.85 (± 0.04) mm on the control side, with the difference between them being statistically significant (p < 0.001). Величина ретракции верхнечелюстного клыка в разные моменты времени описана в таблице 3 для обеих групп А и В. В группе А наибольшее среднее расстояние (± SD), пройденное верхнечелюстным клыком на 3-й неделе, составляет 1,18 (± 0,04) мм на стороне лазера и 0,85 (± 0,04) мм на стороне контроля, при этом разница между ними статистически значима (p < 0,001). The amount of retraction of the maxillary canine at different time points is described in Table 3 for both groups A and B. In group A, the longest mean distance (± SD) traveled by the maxillary canine at week 3 is 1.18 (± 0.04) mm on the laser side and 0.85 (± 0.04) mm on the control side, while the difference between them is statistically significant (p < 0.001). For groups A and B, the degree of maxillary canine retraction at different time points is described in Table 3.在A 组中，上颌尖牙移动的最大平均距离(± SD) 在第3 周报告为激光侧为1.18 (± 0.04) mm，对照侧为0.85 (± 0.04) mm，两者之间的差异具有统计学意义（p < 0.001）。在 a 组 中 ， 上 颌 移动 的 最 大 距离 距离 距离 在 在 第 3 周 报告 为 激光 侧 为 1.18 (± 0.04) mm ， 对照侧 为 0.85 (± 0.04) mm ， 两 之间 的 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有 具有统计学意义（p < 0.001）。 В группе А максимальное среднее расстояние (± SD) движения клыков верхней челюсти на 3-й неделе составило 1,18 (± 0,04) мм на стороне лазера и 0,85 (± 0,04) мм на стороне контроля, разница между ними была Статистическая значимость (p < 0,001). In group A, the maximum mean distance (± SD) of maxillary canine movement at week 3 was 1.18 (± 0.04) mm on the laser side and 0.85 (± 0.04) mm on the control side, the difference between they were statistically significant (p < 0.001). However, the mean amount of tooth movement decreased at the 6th week on both the laser and control sides, then gradually increased afterwards over the 9th and 12th weeks, with the amount of tooth movement being significantly higher on the laser side in comparison with the control side (p < 0.001), at all the time points. However, the mean amount of tooth movement decreased at the 6th week on both the laser and control sides, then gradually increased afterwards over the 9th and 12th weeks, with the amount of tooth movement being significantly higher on the laser side in comparison with the control side (p < 0.001), at all the time points. However, the mean amount of tooth displacement decreased at week 6 on both the laser and control sides, and then gradually increased during weeks 9 and 12, with the amount of tooth displacement significantly higher on the laser side. laser compared with the control group. стороны (p < 0,001) во все моменты времени. side (p < 0.001) at all times.然而，激光侧和对照侧的平均牙齿移动量在第6 周下降，然后在第9 周和第12 周后逐渐增加，与对照相比，激光侧的牙齿移动量明显更高侧（p < 0.001），在所有时间点。然而 ， 激光 侧 和 对照侧 的 牙齿 移动量 在 第 6 周 下降 ， 然后 第 第 第 周 和 第 第 12 周 逐渐 增加 ， 与 对照 相比 ， 的 移动量 明显 更 高侧 （p <0.001 ），在所有时间点。 Однако среднее количество движений зубов на стороне лазера и контрольной стороне уменьшилось на 6-й неделе, а затем постепенно увеличилось через 9 и 12 недель, а количество движений зубов на стороне лазера было значительно выше по сравнению с контрольной стороной (p <0,001) во все моменты времени. However, the mean number of tooth movements on the laser side and the control side decreased at week 6 and then gradually increased after 9 and 12 weeks, and the number of tooth movements on the laser side was significantly higher compared to the control side (p<0.001) at all points in time. The total amount of tooth movement (± SD) over the 12-week study period was significantly higher on the laser side with 4.45 (± 0.13) mm, compared to that on the control side which was 3.16 (± 0.14) mm (p < 0.001). The total amount of tooth movement (± SD) over the 12-week study period was significantly higher on the laser side with 4.45 (± 0.13) mm, compared to that on the control side which was 3.16 (± 0.14) mm (p < 0.001). Общая величина смещения зубов (± SD) за 12-недельный период исследования была значительно выше на стороне лазера – 4,45 (± 0,13) мм по сравнению с контрольной стороной, которая составляла 3,16 (± 0,14) мм (p < 0,001). The total amount of tooth displacement (± SD) over the 12-week study period was significantly higher on the laser side, 4.45 (± 0.13) mm, compared to the control side, which was 3.16 (± 0.14) mm ( p < 0.001).在为期12 周的研究期间，激光侧的牙齿移动总量(± SD) 显着更高，为4.45 (± 0.13) mm，而对照组为3.16 (± 0.14) mm (p < 0.001)。在为期12 周的研究期间，激光侧的牙齿的牙齿纻动总量(± SD) 显着更高，为4.45 (± 0.13) mm，而对照组40人3.16 (± 0.16) (± 0.16) (± 0.16) (± 0.16 (± 0.16) (± 0.16) (± 0.16) В течение 12-недельного периода исследования общее перемещение зубов (± SD) было значительно выше на стороне лазера и составляло 4,45 (± 0,13) мм по сравнению с 3,16 (± 0,14) мм в контрольной группе (p < 0,001). During the 12-week study period, total tooth movement (± SD) was significantly higher on the laser side at 4.45 (± 0.13) mm compared to 3.16 (± 0.14) mm in the control group (p < 0.001).
In Group B, a similar pattern to that demonstrated in Group A has been followed, with significantly higher values of tooth movement being recorded on the laser side, in comparison to the control side at all time points (p < 0.001). In Group B, a similar pattern to that demonstrated in Group A has been followed, with significantly higher values ​​of tooth movement being recorded on the laser side, in comparison to the control side at all time points (p < 0.001). В группе B наблюдалась аналогичная картина, продемонстрированная в группе A, со значительно более высокими значениями движения зубов, зарегистрированными на стороне лазера, по сравнению с контрольной стороной во все моменты времени (p < 0,001). Group B showed a similar pattern to Group A, with significantly higher tooth movement values ​​recorded on the laser side compared to the control side at all time points (p < 0.001).在B 组中，遵循与A 组相似的模式，与所有时间点的对照侧相比，激光侧记录的牙齿移动值显着更高（p < 0.001）。 <0.00 В группе B, по аналогии с группой A, зарегистрированные значения перемещения зубов были значительно выше на стороне лазера по сравнению с контрольной стороной во все моменты времени (p < 0,001). In group B, similar to group A, the recorded values ​​of tooth movement were significantly higher on the laser side compared to the control side at all time points (p < 0.001). After 3 weeks, maximum tooth movement (± SD) was recorded with a value of 1.14 (± 0.04) mm on the laser side and 0.87 (± 0.03) mm on the control side. Tooth mobility subsequently decreased at week 6 and then gradually increased. The total amount of canine retraction (± SD) over the 12-week study period on the laser and control sides, was 4.35 (± 0.12) mm, and 3.10 (± 0.06) mm, respectively, and the difference between them was statistically significant (p < 0.001). The total amount of canine retraction (± SD) over the 12-week study period on the laser and control sides, was 4.35 (± 0.12) mm, and 3.10 (± 0.06) mm, respectively, and the difference between them was statistically significant (p < 0.001). The total canine retraction (± SD) over the 12-week study period on the laser and control sides was 4.35 (± 0.12) mm and 3.10 (± 0.06) mm, respectively, and the difference between them was statistically significant . (р < 0,001). (p < 0.001).在为期12 周的研究期间，激光侧和对照侧的犬齿回缩总量(± SD) 分别为4.35 (± 0.12) mm 和3.10 (± 0.06) mm，它们之间的差异具有统计学意义(p < 0.001)。在 为期 12 周 的 研究 ， 激光 侧 和 对照侧 的 回缩 总量 总量 总量 (± sd) 分别 为 4.35 (± 0.12) mm 和 3.10 (± 0.06) mm ， 之间 的 差异 具有 统计学 意义 (p (p < 0.001)。 В течение 12-недельного периода исследования общая (± SD) ретракция клыка на стороне лазера и контрольной стороне составила 4,35 (± 0,12) мм и 3,10 (± 0,06) мм соответственно, и разница была статистически значимой (p < 0,001). During the 12-week study period, total (± SD) canine retraction on the laser side and control side was 4.35 (± 0.12) mm and 3.10 (± 0.06) mm, respectively, and the difference was statistically significant ( p < 0.001). . Table 4 describes the comparison of the degree of canine retraction at different time points between laser and control side in each study group.
Although the degree of canine retraction by the laser was higher in group A than in group B at all time points, this difference was not considered statistically significant compared to group B (p = 0.08-0.55). Regarding the percentage increase (± SD) in canine retraction achieved with each protocol, the protocol used in group A increased by 40.78 (± 4.81)%, while the protocol used in group A increased by 40 .22 (± 4.80) % in group B. laser application protocol received. However, although this percentage was slightly higher in group A than in group B, the difference between them was not statistically significant (p = 0.82). In addition, it was found that the nature of the movement of the teeth in both groups is relatively the same (Fig. 7).
Laser retraction of the lateral canine (mm) at different time points in both study groups during the 12-week study period.
Table 5 describes the levels of IL-1β in groups A and B at all measured time points on the laser and control sides. In group A, the difference between laser side and control side at baseline was not significant for IL-1β values ​​(p = 0.56). The highest level of IL-1β (± SD) was recorded at day 7 on both the laser and control sides, with values of 0.152 (± 0.004) pg/ml/60 s, and 0.127 (± 0.004) pg/ml/60 s, respectively, and the difference between them was statistically significant (p < 0.001). The highest level of IL-1β (± SD) was recorded at day 7 on both the laser and control sides, with values ​​of 0.152 (± 0.004) pg/ml/60 s, and 0.127 (± 0.004) pg/ml/60 s, respectively, and the difference between them was statistically significant (p < 0.001). The highest level of IL-1β (± SD) was recorded on day 7 on both laser and control sides with values ​​of 0.152 (± 0.004) pg/mL/60 s and 0.127 (± 0.004) pg/mL. /60 с соответственно, а разница между ними была статистически значимой (p < 0,001). /60 s, respectively, and the difference between them was statistically significant (p < 0.001).在第7 天，激光侧和对照侧均记录到最高水平的IL-1β (± SD)，值为0.152 (± 0.004) pg/ml/60 s 和0.127 (± 0.004) pg/ml/60 s，它们之间的差异具有统计学意义（p < 0.001）。在第7 天，激光侧和对照侧均记录到最高水平的IL-1β (± SD)，值为0.152 (± 0.004) pg/ml/60 s 和0.127 (± 0.004) pg/ml/6 p < 0.001）。 On day 7, the highest levels of IL-1β (± SD) were recorded on both the laser and control sides with values ​​of 0.152 (± 0.004) pg/mL/60 s and 0.127 (± 0.004) pg/mL. /60 s. Разница между ними была статистически значимой (p < 0,001). The difference between them was statistically significant (p < 0.001). A gradual decrease in IL-1β levels has been reported thereafter, on days 14 and 21, on both the laser and control sides, with the values on the laser side being significantly higher than those on the control side (p < 0.001). A gradual decrease in IL-1β levels has been reported thereafter, on days 14 and 21, on both the laser and control sides, with the values ​​on the laser side being significantly higher than those on the control side (p < 0.001). После этого сообщалось о постепенном снижении уровней IL-1β на 14 и 21 день как на стороне лазера, так и на стороне контроля, при этом значения на стороне лазера были значительно выше, чем на стороне контроля (p <0,001). Thereafter, a gradual decrease in IL-1β levels was reported at days 14 and 21 on both the laser and control sides, with values ​​on the laser side being significantly higher than those on the control side (p<0.001). .此后，在第14 天和第21 天，激光和对照侧的IL-1β 水平逐渐下降，激光侧的值显着高于对照侧的值(p < 0.001)。此后，在第14 天和第21 天，激光和对照侧的IL-1β 水平逐渐下降，激光侧的值显着高于对照侧的值( После этого на 14-й и 21-й дни уровни ИЛ-1β постепенно снижались на стороне лазера и в контроле, при этом значения на стороне лазера были значительно выше, чем на стороне контроля (p < 0,001). After that, on the 14th and 21st days, the levels of IL-1β gradually decreased on the laser side and in the control, while the values ​​on the laser side were significantly higher than on the control side (p < 0.001).
In group B, a similar pattern was observed in group A with respect to IL-1β levels, with minor differences observed at baseline between laser and control sides (p = 0.02). After 7 days, the peak of IL-1β level (± SD) was reached on both sides, with 0.139 (± 0.004) pg/ml/60 s on the laser side, and 0.122 (± 0.003) pg/ml/60 s on the control side, with the values on the laser side considered statistically higher (p < 0.001). After 7 days, the peak of IL-1β level (± SD) was reached on both sides, with 0.139 (± 0.004) pg/ml/60 s on the laser side, and 0.122 (± 0.003) pg/ml/60 s on the control side, with the values ​​on the laser side considered statistically higher (p < 0.001). After 7 days, the peak level of IL-1β (± standard deviation) was reached on both sides: 0.139 (± 0.004) pg/ml/60 s on the laser side and 0.122 (± 0.003) pg/ml/60 s. на контрольной стороне, при этом значения на стороне лазера считались статистически более высокими (p < 0,001). on the control side, while the values ​​on the laser side were considered statistically higher (p < 0.001). 7天后，两侧达到IL-1β水平峰值（±SD），激光侧为0.139（±0.004）pg/ml/60 s，激光侧为0.122（±0.003）pg/ml/60 s在控制侧，激光侧的值在统计上更高（p < 0.001）。 7 天 后 ， 两 侧 达到 达到 il-1β 水平 （（±） ， 激光 侧 为 为 为 0.139 （± 0.004） pg/ml/60 S ， 侧 为 0.122 （（0.003） pg/ml/60 s 在 侧 激光 激光 激光 激光 激光 激光 激光 激光 激光 激光 激光 ， ， ， ， ， ， ， ， ， ，侧的值在统计上更高（p < 0.001）。 After 7 days, peak levels of IL-1β (±SD) were achieved on both sides: 0.139 (±0.004) pg/ml/60 s on the laser side and 0.122 (±0.003) pg/ml/60 s on the control side. , лазер Значения на стороне были статистически выше (p < 0,001). , laser Values ​​per side were statistically higher (p < 0.001). IL-1β levels subsequently decreased gradually on both sides at days 14 and 21, and the levels recorded on the laser side were significantly higher compared to the control side at both time points (p = 0.001-0.002). Comparison of IL-1β levels at different time points between the laser side and the control side in each study group is described in Table 6.
When comparing IL-1β levels between the two study groups, a non-significant difference was recorded on the laser side at baseline (p = 0.96). On the 7th and 14th days, statistically significant differences have been registered between the laser sides in both groups, with higher values belonging to the laser sides in Group A (p < 0.001). On the 7th and 14th days, statistically significant differences have been registered between the laser sides in both groups, with higher values ​​belonging to the laser sides in Group A (p < 0.001). На 7-й и 14-й дни зарегистрированы статистически значимые различия между лазерными сторонами в обеих группах, причем более высокие значения принадлежат лазерным сторонам в группе А (р < 0,001). On days 7 and 14, there were statistically significant differences between the laser sides in both groups, with higher values ​​belonging to the laser sides in group A (p < 0.001).在第7 天和第14 天，两组激光侧的差异有统计学意义，A 组激光侧的值较高（p < 0.001）。 A На 7 и 14 дни разница между двумя группами была статистически значимой на стороне лазера с более высокими значениями на стороне лазера в группе А (p < 0,001). On days 7 and 14, the difference between the two groups was statistically significant on the laser side, with higher values ​​on the laser side in group A (p < 0.001). After 21 days, there was no significant difference between the two groups (p = 0.26). The levels of IL-1β in both groups had the same character, reaching a maximum on the 7th day and gradually decreasing on the 14th and 21st days (Fig. 8).
The aim of this study was primarily to evaluate and compare the effect of LILR on canine retraction using a protocol including high frequency laser irradiation on days 0, 3, 7, 14 and every 2 weeks thereafter (Group A) with the most recently entered patients. there were fewer recalls compared to a regimen in which laser exposure was performed at 3-week intervals (group B). Whether it is a general high frequency protocol7,13,26 or a 3-week protocol15,17,18, both protocols are described in the literature. Based on the results presented in the current study, the null hypothesis was not rejected, and through the application of the two protocols studied, relatively equal numbers of dog movements were achieved.
The current study design is a clinical randomized controlled trial (RCT). RCTs are considered the gold standard for evaluating the effects of an intervention27. A split-mouth technique was also used, the main advantage of which is that inter-subject variability is eliminated, with each patient acting as their own controller, thereby reducing the number of participants required.
All subjects included in the study required extraction of the maxillary first premolar followed by canine retraction as part of orthodontic treatment. Since extraction can change the rate of RTM by increasing the activity of inflammatory markers, which in turn can mask the effect of LILT and give false readings of IL-1β levels when using laser, extraction treatment was performed before treatment, which provided a good result. Healing socket extraction solution provides sufficient time and overcomes the effects of regional acceleration phenomena28. This precaution has also been taken by some authors,11 who investigated the effect of LILT on OTM rate during retraction in dogs by measuring levels of biomarkers such as IL-1β and transforming growth factor β1 (TGF-β1) in GCF.
The type of laser used in this study was a diode semiconductor laser used at 980 nm according to the manufacturer’s recommendations for optimal biostimulation. This can be explained by the fact that the longer the laser wavelength (650-1200 nm), the deeper the tissue penetrates29. However, this recommended wavelength has been used in several other studies, producing positive acceleration effects of 8.30 and negative effects of 14.
Another important factor influencing the effectiveness of LILI treatment and biostimulation is the dose or energy density. When reviewing the literature, it was found that there is a huge heterogeneity in the dosage of LILI energy to accelerate the GTM. Some authors report positive results when using low energy densities from 0.7131, 532.33, 7.514 to 8 J/cm234.35, while other researchers also report the effect of LILR on the GTM rate at higher energy densities, for example , 25 J/cm2. cm27.36. In the present work, a dose of low level laser energy of 8 J/cm2 was delivered by a single exposure to the maxillary canine root for 8 seconds using a flat top tip to distribute a beam spot of 1 cm2. There is a direct correlation between beam size and laser penetration depth, which in turn justifies the use of flat top handpieces in this study29,37. The same single application protocol with large beam spot size is performed with alignment and alignment 8 and canine retraction 38 .
IL-1β is known to be an important pro-inflammatory cytokine at the onset of OTM and is considered a marker of bone resorption. Therefore, IL-1β levels have been assessed by laser in several studies11,39,40 in an attempt to determine their correlation. In the current trial, IL-1β levels in GCF were assessed on the experimental and control sides of each group by applying two different regimens of LILI on days 0, 7, 14, and 21.
In the present study, canine retraction by the laser in groups A and B was significantly higher than in the control group at all time points assessed, peaking at week 3, declining for one week at week 6, and then gradually increasing up to week 12 . . Peak canine movement noted at week 3 can be explained by the effect of initial tooth displacement, including: root displacement in the PDL, bone deformity due to flexure and creep, and compressive pressure of the tooth due to the inclination of the conical socket Plane effect 41. In addition, it has been found that all active biological processes are accelerated when the bone remains in a deformed position. The subsequent slowdown seen between 3 and 6 weeks, possibly due to a delay period that can vary from 2 to 10 weeks, is a period of PDL disruption that resorbs and removes bone adjacent to the crush area, allowing bone movement. teeth. Another contributing factor to this observation may be that oxygenated fibers, collagen fibers, and alveolar bone remodeling on the side of tension may also limit the rate of tooth movement. Similar patterns of tooth movement were found in a cleft study45 comparing the effects of LILI and corticotomy on canine retraction rate, they noted that tooth movement was greatest at weeks 2 and 5, followed by a sharp decline at 2 and 5 weeks. th week. This was not reported on the laser side at week 7, but not on the corticotomy side.
The reported mean percentage increase in the distance of movement of the maxillary canine from the side of the laser was 40.78% in group A and 40.22% in group B. The apparent increase in tooth mobility that accompanies the use of the laser can be explained at the cellular level by the absorption of laser energy by photoreceptors in the electron- transport respiratory chain within the mitochondrial membrane. This effect leads to short-term activation of the respiratory chain, which leads to oxidative phosphorylation and changes in the redox state of cellular mitochondria and cytoplasm. In turn, the driving force of the cell is increased by increasing the supply of ATP. In addition, there is an increase in the potential of the mitochondrial membrane, alkalization of the cytoplasm, and the synthesis of nucleic acids. Since ATP is known to be the energy currency of cells, LILI contributes to the normal functioning of cells by creating a favorable environment for tooth movement46. Thus, from our results, we can conclude that the use of LILT as an adjunct to orthodontic treatment can successfully accelerate OTM regardless of whether it is used as often as the regimen in group A (on days 0, 3, 7, 14 and every day). after 2 days) weeks), or if used less frequently in group B (every 3 weeks), therefore, the null hypothesis was not rejected.
The relatively identical accelerating effects of the two tested LILT protocols reported in this study may be due to the presence of a cellular activation threshold at which increased cellular activation with LILT exposure occurs initially, but then repeated exposures (as in group A), due to for saturated biological reactions will not lead to further activation. Thus, we can assume that the effects of LLLT at the cellular level cannot be cumulative. Regarding the relationship between force level and tooth movement speed, the concept of biosaturation has been described previously.
After reviewing the existing literature, we compared the 1.4-fold (40-41%) increase in WTM obtained in our study using two laser protocols with the results of several other reports. Some studies have reported similar results11,30,48,49 while others have reported slightly lower acceleration values ​​applied using LILI7,18,32,40. On the other hand, much higher acceleration values ​​than those reported in current tests, ranging from 1.65×17 to nearly 2x OTM15, 34, 39, 50, which may be related to some of them Use self-locking braces without friction 15. This difference in the results published in the literature may be due to different laser application patterns, wavelengths, output power, exposure time, energy density, treatment intervals, etc., which makes direct comparison between different studies quite difficult. . However, it has been noted that lower energy densities (eg 2.5, 5 and 8 J/cm2) provide better acceleration efficiency compared to higher energy densities, it is worth noting that the doses used in our experiments were 8 J/cm2. cm2.
Interpretation of IL-1β levels in the distal cleft (compression side) after analysis of the obtained GCF samples showed a statistically significant increase from baseline (ie peak) on day 7 followed by a gradual decrease to baseline. on panels A and B, on the laser side and on the control side. This can be explained by the fact that the initial phase of OTM is usually accompanied by an increase in osteoclast activity. IL-1β is also considered to be the earliest detectable marker associated with bone resorption, and IL-1β expression has been reported to increase with force and subsequently decrease in multiple studies11,20,51.
In addition, IL-1β levels were higher on the laser side compared to the control group in both study groups at all measured time points except baseline, and there was a statistically significant difference between them. This indicates that low-intensity laser irradiation caused an enhanced biological response in the periodontal tissues on the experimental side in the form of stimulation of osteoclast function on the compressed side during orthodontic tooth movement. This effect of LLLT on IL-1β levels has been demonstrated in various studies11,39,40.
When comparing laser-side IL-1β levels in the two study groups, levels were statistically higher in group A compared to group B at days 7 and 14. This can be explained by a large number of exposures to laser irradiation in group A during the 21-day observation period, where irradiation was carried out on days 0, 3, 7, and 14, and in group B, only 1 shot was fired on day 0. However, although IL-1β levels were statistically higher on the laser side in group A, this statistical difference was not clinically reflected in the degree of retraction in dogs compared to the laser side in group B, as there was no statistical significance. In groups A and B, the reported differences in canine retraction between laser sides actually resulted in the same amount of canine movement. Therefore, we can say that statistical differences do not necessarily explain clinical significance.
Low-intensity laser therapy, when used with the parameters used in this study, can effectively accelerate the movement of orthodontic teeth by about 1.4 times, whether it is applied at a high or low frequency, coinciding with regular follow-up, perhaps. more suitable for patients.
An increase in orthodontic tooth mobility during LILI was accompanied by an increase in the level of interleukin-1β on the compressed side, which indicates that the use of LILI causes an enhanced process of bone remodeling.
The datasets used and/or analyzed in the current study are available from the respective authors upon reasonable request.
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