***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: Dentin hypersensitivity ( DH ) is defined as pain derived from exposed dentin in response to chemical , thermal , tactile , or osmotic stimuli that can not be explained as having arisen from any other dental defect or disease . The aim of this trial was to test the efficacy and the safety of a low-level laser-emitting toothbrush on management of DH . A prospect i ve , double blind , r and omised clinical trial was design ed ; 96 individuals with hypersensitive teeth without caries or fracture were selected as subjects . The subjects were r and omly allocated to either the test group with the 635 nm per 6 mW laser-emitting toothbrush , or the control group with the 635 nm per 12.9 μW light-emitting diode ( LED ) toothbrush . An air blast was applied with a dental air syringe held 3 mm away from the selected tooth and a visual analogue scale ( VAS : 0 - 10 ) was used to quantify subjective pain . Assessment s were completed at a screening visit and after 2-week and 4-week of using a test/control toothbrush . Results demonstrated that the use of both control and test toothbrushes result ed in decreased discomfort after 4 weeks . In the test group , pain intensity scores decreased from 5.8 ± 1.2 to 2.3 ± 1.6 , and in the control group , the scores decreased from 6.4 ± 1.3 to 5.5 ± 2.0 ( P < 0.05 ) . This decrease was significantly greater in the test group . There were no significant adverse events or side effects . It was concluded that the use of the low-level laser emitting toothbrush is a safe and effective treatment option for the management of DH OBJECTIVE The aim of this study was to evaluate the desensitizing effects of a dentifrice containing nano-carbonate apatite ( n-CAP ) and Er , Cr : YSGG laser in the treatment of dentin hypersensitivity . BACKGROUND DATA Most studies of hypersensitivity treatment have been conducted with different methods of professional treatment and self-care in each study . Moreover , clinical studies that compare self-care and professional treatment have not yet been published . METHODS Eighty-two patients with dentin hypersensitivity were divided r and omly into three groups : ( 1 ) a control group with strontium chloride dentifrice ( SC ) , ( 2 ) n-CAP dentifrice ( n-CAP ) , and ( 3 ) an Er , Cr : YSGG laser ( laser ) group . The study was conducted for 4 weeks : a treatment period of 2 weeks and a maintenance period of 2 subsequent weeks . The SC and n-CAP groups were instructed to brush their teeth twice a day for 1 min . The laser group visited twice at 1 week intervals for irradiation of the sensitive teeth . The desensitizing effect was evaluated by assessing the tactile sensitivity using the visual analogue scale ( VAS ) , and evaporative air sensitivity was determined using an air blast score ( ABS ) . RESULTS The n-CAP group and the laser group showed significantly different desensitizing effects in VAS after 4 weeks ( 69 % and 63 % , respectively ) and a 33 % ( p<0.05 ) and 3 % ( p>0.05 ) desensitizing effect , respectively , in VAS during the maintenance period . CONCLUSIONS The n-CAP and the laser were effective in reducing dentin hypersensitivity . The laser had a superior desensitizing effect at the initial stage , whereas the n-CAP maintained its effect for a relatively longer time in clinical situations INTRODUCTION Various methods and material s are used in the treatment of dentin hypersensitivity . The aim of this r and omized prospect i ve controlled clinical trial was to evaluate and compare the desensitizing effects of the neodymium-doped yttrium aluminium garnet ( Nd : YAG ) laser and fluoride varnish by considering the degree of pre- and posttreatment pain , discomfort , and functional complications . METHODS Twenty patients with clinical ly diagnosed cervical dentin hypersensitive teeth were included and r and omly allocated to either the application of fluoride varnish ( group fluoride ) or Nd : YAG laser ( 100 mJ , 20 Hz ; group Nd : YAG ) . The assessment of pain and discomfort was performed by a visual analog scale after an air blast at baseline , immediately after treatment , and at patient visits on weeks 1 , 2 , 3 , and 4 . RESULTS Laser treatment result ed in significant improvements of discomfort immediately after treatment and after 1 week . At the 2- , 3- , and 4-week examination , the discomfort in group fluoride decreased up to nearly 75 % to 85 % of baseline scores , whereas the effect of the laser stayed nearly unchanged . The visual analog scale scores for pain at 4 weeks examination were significantly lower in the fluoride group compared with those in the laser group ( p < 0.05 ) . CONCLUSIONS Nd : YAG laser is a suitable tool for the immediately successful reduction of dentinal hypersensitivity and has better patient satisfaction and shorter treatment time Objectives : To estimate the effects of low level laser therapy in combination with a programme of exercises on pain , functionality , range of motion , muscular strength and quality of life in patients with osteoarthritis of the knee . Design : A r and omized double-blind placebo-controlled trial with sequential allocation of patients to different treatment groups . Setting : Special Rehabilitation Services . Subjects : Forty participants with knee osteoarthritis , 2–4 osteoarthritis degree , aged between 50 and 75 years and both genders . Intervention : Participants were r and omized into one of two groups : the laser group ( low level laser therapy dose of 3 J and exercises ) or placebo group ( placebo laser and exercises ) . Main measures : Pain was assessed using a visual analogue scale ( VAS ) , functionality using the Lequesne question naire , range of motion with a universal goniometer , muscular strength using a dynamometer , and activity using the Western Ontario and McMaster Universities Osteoarthritis ( WOMAC ) question naire at three time points : ( T1 ) baseline , ( T2 ) after the end of laser therapy ( three weeks ) and ( T3 ) the end of the exercises ( 11 weeks ) . Results : When comparing groups , significant differences in the activity were also found ( P = 0.03 ) . No other significant differences ( P > 0.05 ) were observed in other variables . In intragroup analysis , participants in the laser group had significant improvement , relative to baseline , on pain ( P = 0.001 ) , range of motion ( P = 0.01 ) , functionality ( P = 0.001 ) and activity ( P < 0.001 ) . No significant improvement was seen in the placebo group . Conclusion : Our findings suggest that low level laser therapy when associated with exercises is effective in yielding pain relief , function and activity on patients with osteoarthritis of the knees Chronic pain is defined as pain that persists for greater than 12 weeks ( Task-Force , 1994 ) and currently affects roughly 30 % of the population in the United States ( Johannes et al. , 2010 ) . The most common method for managing chronic pain has traditionally been pharmacological ( Nalamachu , 2013 ) . These treatments often include non-steroidal anti-inflammatory drugs ( NSAIDS ) , opioids , acetaminophen , and anticonvulsants ( Nalamachu , 2013 ) . Alternative medicine is now also being used more frequently to treat chronic pain and may consist of acupuncture ( McKee et al. , 2013 ) , Tai Chi ( Wang et al. , 2010 ; Wang , 2012 ) , and low-level laser therapy ( LLLT ) ( Enwemeka et al. , 2004 ; Ay et al. , 2010 ) . The focus of this manuscript is to highlight the physiological aspects of LLLT , and to discuss its application for those suffering from chronic pain , alone and in combination with exercise . It will also provide justification for the use of LLLT using specific data and case studies from the existing literature which have result ed in positive outcomes for those suffering from chronic pain . The physiological mechanisms of LLLT are not well-understood and the mechanisms tend to be very broad ( Yamamoto et al. , 1988 ; Kudoh et al. , 1989 ; Campana et al. , 1993 ; Sakurai et al. , 2000 ; Chow et al. , 2007 ; Moriyama et al. , 2009 ; Cidral-Filho et al. , 2014 ) . One hypothesis is that there may be an increase in nociceptive threshold after LLLT result ing in neural blockade , specifically an inhibition of A and C neural fibers ( Kudoh et al. , 1989 ; Chow et al. , 2007 ) . This inhibition may be mediated by altering the axonal flow ( Chow et al. , 2007 ) or by inhibiting neural enzymes ( Kudoh et al. , 1989 ) . In addition , data suggests an increase in endorphin production ( Yamamoto et al. , 1988 ) and opioid-receptor binding via opioid-containing leukocytes with LLLT ( Cidral-Filho et al. , 2014 ) . LLLT may also mimic the effects of anti-inflammatory drugs by attenuating levels of prostagl and in-2 ( PGE2 ) ( Campana et al. , 1993 ) and inhibiting cyclooxygenase-2 ( COX-2 ) ( Sakurai et al. , 2000 ) . In addition , data have suggested that LLLT may augment levels of nitric oxide , a powerful vasodilator , which would in turn act to increase blood flow and assist with healing ( Samoilova et al. , 2008 ; Moriyama et al. , 2009 ; Cidral-Filho et al. , 2014 ; Mitchell and Mack , 2013 ) . While the mechanisms have not been completely explained , it is clear that LLLT may have an analgesic effect . Studies have demonstrated that LLLT may have positive effects on symptomology associated with chronic pain ( Fulop et al. , 2010 ; Hsieh and Lee , 2013 ) ; however this finding is not universal ( Ay et al. , 2010 ) . A meta- analysis utilizing 52 effect sizes from 22 articles on LLLT and pain from Fulop et al. ( 2010 ) demonstrated an overall effect size of 0.84 . This would be classified as a large effect size and suggests a strong inclination for the use of LLLT to reduce chronic pain . Twenty-two studies were utilized with doses ranging from 1 to 30 J/cm2 . On the other h and , a meta- analysis from Gam et al. ( 1993 ) demonstrated no effect of LLLT on musculoskeletal pain but this study was published over 20 years ago when LLLT was just emerging . More recently data from Ay et al. ( 2010 ) have reported no difference in chronic pain compared to placebo using twice weekly treatment 5 days a week for 3 weeks . Treatment consisted of a total energy of 40 J/cm2 ( 850 nm , 100 mV , a treatment spot area of 0.07 cm2 , 4 min over each of the four different points ) . Taken together , it is hard to assess whether LLLT is an effective modality . However , it is clear that LLLT may be effective in treating chronic pain in many individuals and should not be overlooked as a treatment modality . A systematic review and meta- analysis from 16 r and omized control studies on LLLT and neck pain ( Chow et al. , 2009 ) interpreted the analysis that LLLT caused an immediate decrease in pain for acute neck pain and up to 22 weeks post in  chronic neck pain patients . Recently , in a double blinded placebo control study Leal et al. ( 2014 ) reported a decrease pain and increase in function in patients with knee pain . One issue with these meta-analyses is that participants were grouped together , under the heading of chronic pain . However , chronic pain has different manifestations which inhibit the ability to make general observations . Separate subheadings of chronic pain may include but are not limited to chronic neck pain and lower back pain , myofascial pain syndrome , and fibromyalgia . A meta- analysis by Gross et al. ( 2013 ) worked to separate out the effect of LLLT on a variety of different conditions . Based on their review , the effect of LLLT on chronic neck pain has a moderate level of evidence for effectiveness when using 830 or 940 nm but not 632.8 nm . However , it was mentioned that the trials investigating chronic neck pain and LLLT failed to blind participants which may limit the application of the data . The authors also included the effect of LLLT on myofascial pain syndrome and reported that the data are mixed and evidence is lacking . In addition , LLLT treatments have been reported to be effective for decreasing pain and increasing function in other chronic pain pathologies including fibromyalgia syndrome ( Gur et al. , 2002a , b ; Armagan et al. , 2006 ; Moore and Demchak , 2012 ) . Studies that examine the use of LLLT combined with exercise seem to have merit , as exercise is a staple of rehabilitation . Interestingly , Djavid et al. ( 2007 ) and Gur et al. ( 2003 ) both combined LLLT with exercise and each reported no additional effect of exercise in patients with chronic lower back pain . Djavid et al. utilized 27 J/cm2 of total energy ( 810 nm , 5 
    Output:
    
The profound findings proved lasers ' effectiveness as a treatment of DH .
Although some of the research es reported no significant difference between laser and other desensitizing agents , most of the studies suggested that better results ( both rapid and long-lasting ) were obtained in combined modalities .
Furthermore , the preventive role of this new technology has been emphasized as well .
Nd-YAG ( neodymium-doped yttrium aluminum garnet ) and diode lasers reduce DH after bleaching .
Lasers can also protect cervical restorations from DH due to tubular occlusion .
Moreover , it is suggested to apply lasers in relief of DH following scaling and root planning .
Conclusion : The results obtained from several studies in the present review revealed that the application of lasers is effective not only in terms of treatment of DH , but also in the prevention of this intensive tooth pain .
Among various types of lasers , the application of Nd : YAG laser has shown the best results in DH treatment