***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Introduction : The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats . Material and Methods : Forty eight female three-month old Wistar rats with an average weight of 250±25 gr were selected and r and omly divided into two experimental ( pregnant ) and control groups ( non-pregnant ) . Maxillary central incisors were tipped distally by insertion of springs exerting 30 g force . Two , seven and fourteen days after spring insertion animals were sacrificed . Then the mesioincisal distance between maxillary incisors were measured . Subsequently , histological sections were prepared to count osteoclasts under a light microscope . The data on the extent of orthodontic tooth movement , and the number of osteoclasts were analyzed by independent sample t-test . Results : The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups ( p>0.05 ) . The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion ( p<0.05 ) . Conclusion : Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant . The number of osteoclasts is significantly decreased during pregnancy . Key words : Pregnancy , rat , orthodontic tooth movement , osteoclast Background : Fixed orthodontic treatment is time-consuming procedure . Pain is usually associated with orthodontic treatment . The aim of the present study was to evaluate the role of low-level laser therapy ( LLLT ) on orthodontic tooth movement ( OTM ) duration and pain perception . Material s and Methods : This r and omized double-blind splint-mouth controlled clinical study includes 20 ( 8 males and 12 females ) orthodontic patients requiring bilateral canine retraction . Time taken for canine retraction with LLLT ( Group A ) over control ( Group B ) quadrant on the same patient was assessed along with pain experience using facial pain scale . The data were tabulated and statistically evaluated using SPSS 20 for windows ( Microsoft , Chicago , IL , USA ) and t-test with P < 0.05 . The difference in pain was evaluated with Wilcoxon signed-rank test . Results : There was no difference in values for age and sex of patient for tooth movement and pain ( P > 0.05 ) . There was statistically significant decrease in rate of canine retraction in Group A compared to Group B. There was statistically significant difference for maxillary and m and ibular arches in Group A whereas it was not significant in Group B. Pain experience was statistically significant till 2nd day , and after 3rd day , it was not significant between the groups . Conclusion : LLLT can reduce the fixed OTM timing and pain experience Objectives : One major drawback of orthodontic treatment is its long duration due to slow tooth movement and the pain at the onset of treatment following application of forces . There is controversy regarding the efficacy of laser for decreasing the treatment time and pain of orthodontic treatment . The purpose of this study was to investigate the effect of low level diode laser on the rate of orthodontic tooth movement and the associated pain . Material s and Methods : In this double blind r and omized controlled clinical trial , 12 orthodontic patients referring to Shahid Beheshti School of Dentistry for first premolar extraction were r and omly selected and allocated to gallium aluminum-arsenide laser ( GA-AL-AS diode laser , 880 nm , 100 mW , 5 j/cm2 , 8 points , 80 seconds , continuous mode ) or control group . The patients initially underwent leveling and alignment using the sectional system . Force ( 150 gr ) was applied to each canine tooth via sectional closing loops . The loops were activated every month . The rate of tooth movement and pain were monitored over the treatment period and recorded on days 1 , 3 , 7 , 30 , 33 , 37 , 60 , 63 and 67 . Two-way ANOVA was used for comparison of groups . Results : There was no significant difference in terms of tooth movement and pain scores between the irradiated and non-irradiated sides at any time point ( P>0.05 ) . Conclusion : Although laser enhanced orthodontic tooth movement in the upper jaw , we failed to provide solid evidence to support the efficacy of laser for expediting tooth movement or reducing the associated pain Aim . To evaluate the effect of Low Level Laser Therapy ( LLLT ) on human gingival fibroblasts in terms of proliferation and growth factors ' secretion ( EGF , bFGF , and VEGF ) . Material s and Methods . Primary cultures of keratinized mucosa fibroblasts were irradiated by a Nd : YAG laser 1064 nm with the following energy densities : 2.6 J/cm2 , 5.3 J/cm2 , 7.9 J/cm2 , and 15.8 J/cm2 . Controls were not irradiated . Cultures were examined for cell proliferation and growth factors ' secretion after 24 , 48 , and 72 hours . All experimental procedures were performed in duplicate . Data were analyzed by Student 's t-test ( p < 0.05 ) . Results . All laser-irradiation doses applied promoted a higher cell proliferation at 48 hours in a dose-response relationship compared to controls . This difference reached statistical significance for the cultures receiving 15.8 J/cm2 ( p = 0.03 ) . Regarding EGF , all laser irradiation doses applied promoted a higher secretion at 48 hours in a reverse dose-response pattern compared to controls . This difference reached statistical significance for the cultures receiving 2.6 J/cm2 ( p = 0.04 ) . EGF levels at the other time points , bFGF , and VEGF showed a r and om variation between the groups . Conclusion . Within the limits of this study , LLLT ( Nd : YAG ) may induce gingival fibroblasts ' proliferation and upregulate the secretion of EGF . Further studies are needed to confirm these results Background Numerous strategies have been proposed to decrease the treatment time a patient requires in orthodontic treatment . Recently , a number of device-accelerated therapies have emerged in orthodontics . Photobiomodulation is an emerging area of science that has clinical applications in a number of human biological processes . The aim of this study was to determine if photobiomodulation reduces the treatment time in the alignment phase of orthodontic treatment . Methods This multicenter clinical trial was performed on 90 subjects ( 73 test subjects and 17 controls ) , and  Little 's Index of Irregularity ( LII )  was used as a measure of the rate of change of tooth movement . Subjects requiring orthodontic treatment were recruited into the study , and the LII was measured at regular time intervals . Test subjects used a device which produced near-infrared light with a continuous 850-nm wavelength . The surface of the cheek was irradiated with a power density of 60 mW/cm2 for 20 or 30 min/day or 60 min/week to achieve total energy densities of 72 , 108 , or 216 J/cm2 , respectively . All subjects were fitted with traditional orthodontic brackets and wires . The wire sequences for each site were st and ardized to an initial round alignment wire ( 014 NiTi or 016 NiTi ) and then advanced through a progression of stiffer arch wires unit alignment occurred ( LII < 1 mm ) . Results The mean LII scores at the start of the clinical trial for the test and control groups were 6.35 and 5.04 mm , respectively . Multi-level mixed effect regression analysis was performed on the data , and the mean rate of change in LII was 0.49 and 1.12 mm/week for the control and test groups , respectively . Conclusions Photobiomodulation produced clinical ly significant changes in the rates of tooth movement as compared to the control group during the alignment phase of orthodontic treatment OBJECTIVE To evaluate the effectiveness of low-level laser therapy ( LLLT ) in accelerating orthodontic tooth movement of crowded maxillary incisors . MATERIAL S AND METHODS This two-arm , parallel-group , r and omized controlled trial involved 26 patients with severe to extreme maxillary incisors irregularity according to Little 's irregularity index , indicating two first premolars extraction . Patients were r and omly assigned to either the laser group or the control group ( 13 each ) . Following premolars extraction , orthodontic treatment with fixed appliances was initiated for both groups . Immediately after insertion of the first archwire , patients in the laser group received a LLL dose from an 830-nm wavelength Ga-Al-As semiconductor laser device with energy of 2 J/point . The laser was applied to each maxillary incisor 's root at four points ( two buccal , two palatal ) . Application was repeated on days 3 , 7 , 14 , and then every 15 days starting from the second month until the end of the leveling and alignment stage . Alignment progress was evaluated on the study casts taken before inserting the first archwire ( T0 ) , after 1 month of treatment commencement ( T1 ) , after 2 months ( T2 ) , and at the end of the leveling and alignment stage ( T3 ) . The outcome measures were the overall time needed for leveling and alignment and the leveling and alignment improvement percentage . RESULTS A statistically significant difference was found between the two groups in the overall treatment time ( P < .001 ) and the leveling and alignment improvement percentage at T1 ( P = .004 ) and T2 ; ( P = .001 ) . CONCLUSION LLLT is an effective method for accelerating orthodontic tooth movement The aim of this study was to evaluate the effects of low-level laser irradiation on the rate of orthodontic tooth movement ( OTM ) and the interleukin-6 ( IL-6 ) concentration in gingival crevicular fluid ( GCF ) during orthodontic treatment . In this r and omized split-mouth double blind clinical trial , 11 female patients aged 14 to 25 years ( mean 19 ± 4.21 year ) , who required canine retraction following four first premolars extraction , were selected . The GaAlAs laser diode laser ( A.R.C. Laser GmbH , Nürnberg , Germany ) ( 980 nm , 100 mW , 5.6 J/cm2 , three points from the buccal side and three from lingual side of the tooth , 56 s , running in continuous mode ) was used for canine retraction in only one maxillary quadrant ( LG ) . The irradiation time for each cervical and middle third of the tooth was 10 s , and 8 s for the apical third of the tooth . The other maxillary quadrant served as the control group ( CG ) using the laser pseudo-application in this side . The laser irradiation was applied on days 0 , 7 , 14 , 21 , and 28 of each month during the canine retraction phase . Canine retraction was done using closed coil spring with 150 g force on rectangular wires after the alignment and leveling . This study was done in 11 months . Dental casts were made at different time points during the treatment , and the amount of tooth movement was measured . To evaluate the levels of IL-6 , GCF sample s were collected from the distal side of the maxillary canine teeth on both quadrants at the beginning of the trial , the end of aligning phase , and on day 21 of each month during canine retraction . Although the mean rate of canine retraction was higher in the LG ( 0.013 ) than the CG ( 0.012 ) and there was definitely a tendency for more canine retraction in the LLLI , but the results failed to show any significant difference between the mean rate of canine retraction of both groups ( P = 0.068 ) . A paired t test showed that there was no significant difference in the mean concentration of IL-6 at various stages of the treatment between the groups during canine distalization ( P > 0.05 ) . Therefore , conclusive evidence could not be provided to support the efficacy of the diode laser ( 980 nm ) in accelerating OTM in female subject OBJECTIVES To test the hypothesis that mechanical forces combined with low-level laser therapy stimulate the rate of orthodontic tooth movement . STUDY DESIGN This study was a double blind , r and omized placebo/control matched pairs clinical trial to test the efficacy of GaAlAs low-level laser therapy ( LLLT ) on 12 young adult patients who required retraction of maxillary canines into first premolar extraction spaces using tension coil springs with fixed edgewise appliance . LLLT was applied on the mucosa buccally , distally and palatally to the canine on the test side and using a pseudo-application on the placebo side . Dental impressions and casts were made at the commencement of the trial and at the end of the first , second and third months after starting the trial . Measurement of tooth movements was made on each stage model using a stereo microscope . RESULTS There was no significant difference of means of the canine distal movement between the LLLT side and the placebo side for any time periods ( p-value = 0.77 ) . CONCLUSION The energy density of LLLT ( GaAlAs ) at the surface level in this study ( 25 J/cm(2 ) ) was probably too low to express either stimulatory effect or inhibitory effect on the rate of orthodontic tooth movement Objectives The purpose of this study was to investigate the effects of low-level laser therapy ( LLLT ) with a diode gallium-aluminum-arsenide ( Ga-Al-As ) low-level laser device on the healing and attachment of titanium implants in bone . Material s and Methods Thirteen New Zeal and white male rabbits weighing 3.0±0.5 kg were used for this study . Dental titanium impl 
    Output:
    
Although we have some degree of underst and ing from a cellular point of view to LLLT effects , we still do not know whether these cellular level changes have any effect on the clinical acceleration of orthodontic tooth movement .