***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: This study clinical ly evaluated the alteration of color , color stability , dental sensitivity and gingival irritation on patients undergoing dental bleaching using varying bleaching methods and light-activation sources . According to pre-established criteria , 40 patients were selected and r and omly divided into four groups ( n=10 ) : Group 1 - -35 % Hydrogen Peroxide ( HP ) ; Group 2 - -35 % HP plus Halogen Curing Light XL 3000 ( 3M/ESPE ) ; Group 3 - -35 % HP plus Demetron LED ( Kerr ) and Group 4 - -35 % HP plus LED/LASER ( Bio-art ) . For all groups , there were two sessions of bleaching with 35 % HP , with a one week break between sessions . At each bleaching session , three applications of the bleaching gel were used . Two methods of shade evaluation were performed before and after the first week , second week , first month and after six months of the bleaching treatment . These methods were VITA Easyshade Spectrophotometer and Vita Classical Shade Guide . Statistical analysis using ANOVA demonstrated e quality between the participating groups when evaluating the group and time variables . The In-Office dental bleaching treatments of vital teeth with 35 % HP did not prove to be more effective when light sources were used . There was no difference in color stability between groups until the sixth month of evaluation The objective of this clinical study was to compare the whitening/bleaching efficacy of two marketed in-office whitening systems : Discus Dental Zoom ! Chairside System ( 25 % hydrogen peroxide whitening gel ) and Opalescence Xtra Boost Kit ( 38 % hydrogen peroxide whitening gel ) , using the Vita Shade Guide and chromameter measurements . The study was an examiner-blind , parallel group , r and omized and controlled clinical trial conducted in a dental setting . All subjects signed a study consent form prior to admission and were given Crest Regular Toothpaste and an Oral-B 40 straight-h and le toothbrush to use during the study . Subjects received a supragingival prophylaxis followed by a screening eligibility Vita Shade assessment from which 22 subjects were selected . At baseline , all six maxillary anterior teeth were assessed with the Vita Shade Guide . Chromameter measurements were taken on either the right maxillary central or left maxillary central ( tooth No. 8 or tooth No. 9 ) . Subjects were assigned to one of two treatment groups , and had three applications of their assigned product . Following completion of the treatment phase , and on post-treatment Days 2 and 7 , a visual examination of the condition of the oral soft tissues , together with a Vita Shade assessment on maxillary anterior teeth , a chromameter reading and a question naire regarding tooth sensitivity were completed . At the termination of the study , the statistical analysis of the Vita Shade scores indicated that both products significantly ( p < 0.0001 ) lightened the color of the teeth . The average improvement was between 6 and 9 shade changes . Additionally , the Zoom ! Chairside System was significantly better than the Opalescense Xtra Boost Kit at all time points : post-treatment ( p < 0.0001 ) ; Day 2 ( p < 0.004 ) ; Day 7 ( p < 0.003 ) . This difference was between 1 and 2 shade changes . The chromameter readings showed a significant difference in the overall color change ( delta E ) to a lighter color for both the Zoom ! Chairside System and the Opalescence Xtra Boost Kit . Using delta E , the Zoom ! Chairside System was directionally better than the Opalescense Xtra Boost Kit at Day 2 ( p < 0.08 ) , and significantly better at Day 7 ( p < 0.025 ) . Analysis of the composite parameters of delta E ( L * , a * , b * ) showed that no differences could be detected in the a * ( redness ) parameter . Changes were observed in the L * ( brightness ) and b * ( yellow ) parameters which paralleled the delta E differences . There were no significant differences in induced sensitivity between whitening systems at any time point Mixed treatment comparison ( MTC ) meta- analysis is a generalization of st and ard pairwise meta- analysis for A vs B trials , to data structures that include , for example , A vs B , B vs C , and A vs C trials . There are two roles for MTC : one is to strengthen inference concerning the relative efficacy of two treatments , by including both ' direct ' and ' indirect ' comparisons . The other is to facilitate simultaneous inference regarding all treatments , in order for example to select the best treatment . In this paper , we present a range of Bayesian hierarchical models using the Markov chain Monte Carlo software WinBUGS . These are multivariate r and om effects models that allow for variation in true treatment effects across trials . We consider models where the between-trials variance is homogeneous across treatment comparisons as well as heterogeneous variance models . We also compare models with fixed ( unconstrained ) baseline study effects with models with r and om baselines drawn from a common distribution . These models are applied to an illustrative data set and posterior parameter distributions are compared . We discuss model critique and model selection , illustrating the role of Bayesian deviance analysis , and node-based model criticism . The assumptions underlying the MTC models and their parameterization are also discussed PURPOSE To compare in vitro the bleaching effects obtained with and without the use of the various lights on power bleaching systems . METHODS 19 groups of five tooth specimens were prepared and allocated r and omly to treatments . Only specimens with shade C4 were accepted for the study . Three commercial bleaching products all based on 35 % hydrogen peroxide were used with and without four different light sources . Shade assessment s were made using a Shade Guide ( SG ) , Shade Vision System ( SVS ) and chromometer . RESULTS For SG , all but the light only treatment result ed in measurable improvement in shade ranging from 4.6 to 14.6 shade guide units . Similar findings were apparent with SVS and chromometer . No change was seen in the light only treatments by SVS or SG with very small changes by chromometer . In mean terms with all three gels , least change was noted when there was no light used . For SG , SVS and chromometer data analysis over all treatment groups , excluding light only treatments , revealed highly significant differences . Within bleach product treatment differences were only significant with one gel both with and without light activation . Differences between gels with the same light and no light revealed some significant differences in SG and chromometer data but not SVS . In mean terms the order of efficacy of gels with each light and no light was the same for the majority of data sets Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more OBJECTIVE To compare the bleaching efficacy and tooth sensitivity ( TS ) of two hydrogen peroxide ( HP ) concentrations ( 20 % and 35 % ) used for in-office bleaching associated or not with a light-emitting diode (LED)/laser light activation . METHOD Seventy-seven patients with a right maxillary canine darker than A3 were selected for this single-blind r and omized trial . The participants were distributed in four groups : bleaching with 35 % HP , 35 % HP + LED/laser , 20 % HP , and 20 % HP + LED/laser . The anterior teeth were bleached in two sessions , using a 35 % or 20 % HP gel with a one-week interval . Each session had three applications of 15 minutes . For the light-activated groups , the LED/laser energy ( Whitening Laser Light Plus , DMC ) was employed according to the manufacturer 's instructions . The color change was evaluated by subjective and objective methods . Participants recorded TS with five-point verbal and visual analog scales . Color change in ΔE was evaluated by analysis of variance and Tukey tests ( α=0.05 ) and in ΔSGU with Kruskall-Wallis and Dunn test . The absolute risk of TS and TS intensity were evaluated by Fisher exact test and Kruskall-Wallis test , respectively ( α=0.05 ) . RESULTS All groups achieved the same level of whitening , except for the 20 % HP group , which showed the lowest degree of whitening in the subjective analysis . The use of light did not increase the absolute risk or intensity of TS . No significant difference among groups was observed when color changes were assessed with the spectrophotometer . CONCLUSION According to the value-oriented shade guide , the use of LED/laser light activation was able to increase the degree of whitening of the 20 % HP group , but this association was not useful for the 35 % HP gel . The spectrophotometer , however , did not detect significant differences among groups BACKGROUND The aim of this split-mouth , r and omized controlled trial was to compare the whitening results of at-home and in-office tooth bleaching techniques and the longevity of their effects at nine months after teeth had been bleached . METHODS The authors conducted a study involving a 14-day bleaching period , during which the first maxillary premolars of 17 participants , who were 20 to 25 years of age , were bleached by means of either an at-home technique involving 10 percent carbamide peroxide or an in-office technique involving 38 percent hydrogen peroxide . The authors recorded color variables as proposed by the Commission Internationale de l'Eclairage-lightness ( L * ) , redness ( a * ) and yellowness (b*)-by using a spectrophotometer at baseline and at one week , one month and nine months after bleaching . They also calculated a whiteness ( W ) index that was based on the distance of the color value in the color space from a nominal white point . RESULTS At the nine-month recall visit , comparison between the at-home and the in-office techniques did not show significantly different values for L * ( P = .448 ) , a * ( P = .350 ) , b * ( P = .144 ) and W ( P = .151 ) color variables . None of the participants experienced any adverse events related to the bleaching during the treatment period . CONCLUSIONS The study results showed no clinical ly significant difference in bleaching efficacy . Both techniques produced satisfactory and long-lasting bleaching results . CLINICAL IMPLICATION S In young adults , either the at-home or the in-office technique can be used effectively OBJECTIVE Evaluate a light-enhanced in-office tooth whitening system in order to assess tooth color and safety . METHODS Thirty-three adults were r and omly assigned to one of three treatment groups . Professional treatment involved application of a 25 % H(2)O(2 ) gel ( Discus Dental ZOOM ! ) with light enhancement , H(2)O(2 ) gel alone , or the light alone with no peroxide . The 12 anterior teeth were treated three times for 20 minutes each . Efficacy was measured objective ly as L*a*b * color change using digital images , tooth shade was measured , and safety was evaluated immediately after treatment and at posttreatment days 7 and 30 . RESULTS After adjusting for baseline and age , immediate ( end-of-treatment ) means ( SE ) for Deltab * ( yellowness ) were -3.1 ( 0.25 ) for the gel + light , -2.0 ( 0.25 ) for the gel-only group , and -2.4 ( 0.25 ) for the light-only group . Significant ( p < 0.05 ) color rebound was evident at posttreatment day 7 . By day 30 , adjusted means (SE)for Deltab * were -1.7 ( 0.20 ) for the gel + light group , -1.1 ( 0.20 ) for the gel-only group , and -0.5 ( 0.20 ) for the light-only group . Both peroxide groups differed significantly ( p < 0.05 ) from light alone on Deltab * and DeltaL*. In the gel + light group , 91 % of subjects experienced tooth sensitivity , the majority of which was moderate or severe . Adverse events were low in the light-only group . CONCLUSION Use of light enhancement for in-office whitening leads to immediate color change , after which there was significant color and shade rebound within 7 days as well as moderate-to-severe tooth sensitivity during and after treatment . CLINICAL SIGNIFICANCE Increased tooth sensitivity during treatment and appreciable short-term color rebound after treatment may impact the utility of in-office tooth whitening with peroxide and light as a st and -alone esthetic procedure . ( J Esthet Restor Dent 21:336 - 347 , 2009 ) The purpose of this r and omized , parallel , triple-blinded clinical trial was to compare efficacy and tooth sensitivity ( TS ) after use of an in-office bleaching agent of 6 % hydrogen peroxide containing nanoparticles of nitrogen-doped titanium oxide ( HP6 ) vs. 35 % hydrogen peroxide ( HP35 ) .  Forty-eight volunteers were r and omly divided either a HP6 or HP35 . Two clinical sessions were performed with an interval of 7 days between them for each group . In each session , two consecutive applications of each bleaching agent were performed and activated by a hybrid LED/laser light .  Efficacy was determined by color alteration ( ΔE ) , recorded with reflectance spectroscopy . It was assessed at baseline and after the first and second bleaching session . TS was characterized according to occurrence , intensity , duration , and type . Efficacy was analyzed by repeated measures analysis of variance ( ANOVA ) and post hoc Bonferroni test , and TS was analyzed by means of chi2 test ( α = 0.05 ) . For HP35 , highest and significant values of ΔE were found after bleaching when compared to HP6 ( p = 0.002 ) . However , HP35 showed a significantly higher occurrence of TS than HP6 ( p = 0.00 
    Output:
    
Conclusion No type of light-activated in-office bleaching was superior to light-free in-office bleaching for both high- and low-concentrate in-office bleaching gels ( PROSPERO —CRD42017078743 ) .
Clinical relevance Although many times dental professionals use “ laser whitening ” as a form of marketing , this study confirmed that no type of light-activation for in-office bleaching can improve the bleaching efficacy