Here is the design of a clinical trial:

Official Title: Evaluation of Bleaching In-office With Violet LEd Light (405 nm): Randomized, Controlled Double Blind and Clinical Trial

Included conditions:
- Esthetics, Dental

Study Armgroups:
- {'label': 'Violet LED (405 nm)+ gel placebo', 'type': 'EXPERIMENTAL', 'description': '20 patients will be submitted to dental bleaching involving the teeth 15-25 and 45 - 35 with Violet LED 405 nm (Bright Max Whitening, MMO, São Carlos, SP, Brazil) with gingival barrier + gel placebo', 'interventionNames': ['Other: dental bleaching']}
- {'label': 'Violet LED + CP 35%', 'type': 'ACTIVE_COMPARATOR', 'description': '20 patients will be submitted to dental bleaching involving the teeth 15-25 and 45 - 35 with carbamide peroxide 35% ( Whiteform - Fórmula \\& Ação, São Paulo, Brazil) actived with Violet LED 405 nm (Bright Max Whitening, MMO, São Carlos, SP, Brazil) with gingival barrier', 'interventionNames': ['Other: dental bleaching']}
- {'label': 'HP 35%', 'type': 'ACTIVE_COMPARATOR', 'description': '20 patients will be submitted to dental bleaching involving the teeth 15-25 and 45 - 35 with hydrogen peroxide 35% (Whiteness HP, FGM, Joinvile, SC, Brasil) and gingival barrier', 'interventionNames': ['Other: dental bleaching']}
- {'label': 'HP 35% + Violet LED + Gingivoplasty', 'type': 'EXPERIMENTAL', 'description': '20 patients will be submitted to dental bleaching involving the teeth 15-25 and 45 - 35 with Violet LED 405 nm (Bright Max Whitening, MMO, São Carlos, SP, Brazil) with gingival barrier split-mouth at first session. After 48 hours will be do Gingivoplasty.', 'interventionNames': ['Other: dental bleaching', 'Procedure: Gingivoplasty']}
- {'label': 'CP 35%', 'type': 'ACTIVE_COMPARATOR', 'description': '20 patients will be submitted to dental bleaching involving the teeth 15-25 and 45 - 35 with carbamide peroxide 35% ( Whiteform - Fórmula \\& Ação, São Paulo, Brazil)', 'interventionNames': ['Other: dental bleaching']}

Interventions:
- {'type': 'OTHER', 'name': 'dental bleaching', 'description': 'dental bleaching can be achieved with light, light+ peroxide carbamide gel, or only with peroxide carbamide gel', 'armGroupLabels': ['CP 35%', 'HP 35%', 'HP 35% + Violet LED + Gingivoplasty', 'Violet LED (405 nm)+ gel placebo', 'Violet LED + CP 35%']}
- {'type': 'PROCEDURE', 'name': 'Gingivoplasty', 'description': 'gengivoplasty will be realized to in illuminated tissue an no illuminated tissue to morphometrically evaluate the tissue', 'armGroupLabels': ['HP 35% + Violet LED + Gingivoplasty']}

Primary Outcomes:
- {'measure': 'Color Evaluation', 'description': 'Color evaluation will be done before and after each bleaching session through the Vita Classical scale (VITA Zanhnfabrik, BadSӓckingrn, Germany) and SpectroShade ™ Micro MHT Optic Research by a previously trained and blind evaluator in the 4 groups', 'timeFrame': 'baseline'}
- {'measure': 'Color Evaluation', 'description': 'Color evaluation will be done 3 months after bleaching through the Vita Classical scale (VITA Zanhnfabrik, BadSӓckingrn, Germany) and SpectroShade ™ Micro MHT Optic Research by a previously trained and blind evaluator in the 4 groups', 'timeFrame': '3 months'}

Please estimate the sample size based on the assumption: 
Considering a 5% acceptable rate of error and 95% test power. The protocol has repeated sessions (four sessions), and there is an expected dropout rate due to patients losing interest after achieving a pleasing tooth color.
Calculation of sample size
        Using the G* Power software V.3.1.9.2, the sample size was calculated using analysis of covariance (ANCOVA) F tests with fixed effects, main effects and interactions, since the groups will begin the study with different colour tones, which will influence the final response of each patient.Â We based our sample size calculation on Bernardon et al study, which compares the meanÂ±SD of ÎE differences of four distinct groups.
        The effect size was determined using the following formula:
        
          
            
              
                
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                      m
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                        (
                        
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                  =
                  
                    
                      10.82
                      â
                      8.41
                    
                    
                      
                        (
                        
                          3.62
                          
                            4
                          
                        
                        )
                      
                      
                        2
                      
                    
                  
                  =
                  0.74
                
              
            
          
        
        The effect size is as a standardised index that is independent of sample size and quantifies the magnitude of the difference between populations or the relationship between explanatory and response variables. The largest and smallest mean values as well as the SD (Ï) were based on the literature.5 Considering a 5% acceptable rate of error and 95% test power, 11 patients per group will be necessary to detect differences in tooth whitening (ÎE).
        We believe it will be difficult to maintain adherence of patients in this study. The protocol has repeated sessions (four sessions). As seen in previous studies,39 once teeth have reached a pleasing colour, some patients are not interested in continuing during the follow-up period, just to verify colour stability after bleaching. Therefore, we believe it will be necessary to include more patients in this study. According to our original sample size calculation, only 11 patients were necessary for our study. However, we have included nine more patients in each group to compensate for this drop-out factor.
        Thus, the decision was made to increase the sample to 20 patients per group (total: 80 participants) to compensate for possible drop-outs during the course of the study.
        Once we have reached n=10 patients per group in our study, we will recalculate the sample size based on our own results. We expect there will be a need to increase sample size to find a difference between the groups as there are no controlled clinical studies on this subject (violet LED).