Here is the design of a clinical trial:

Official Title: Efficacy of Photodynamic Therapy and Scraping in Patients With Gingivitis Predisposed by Fixed Orthodontic Appliances: Randomized, Controlled, Double-blind, Split-mouth Study

Included conditions:
- Gingivitis
- Orthodontic Appliance Complication
- Photodynamic Therapy

Study Armgroups:
- {'label': 'scaling and root planing (SRP) + PDT placebo', 'type': 'PLACEBO_COMPARATOR', 'description': '17 patients will receive periodontal treatment (scaling and root planing - SRP) with the ultrasound. The SRP will be done in one session. SRP will be performed by only one experienced researcher. Periodontal reassessment will be performed after 30 days.\n\nThe PDT placebo wil be done using an agent with the same vehicle as that of the methylene blue to mimic irrigation with the photosensitizer; the laser will be switched off at the time of application.', 'interventionNames': ['Procedure: scaling and root planing (SRP) + PDT placebo']}
- {'label': 'scaling and root planing (SRP) + PDT', 'type': 'EXPERIMENTAL', 'description': '17 patients will receive the same scaling and root planing treatment that placebo group.\n\nHowever the PDT will be done only on one side of the mouth using methylene blue 0.005% - Chimiolux 5, DMC - purified water and methylene blue.The red laser diode (λ = 660 nm) will be applied with an output power of 100mW . The laser head will be positioned in direct contact with the pseudo periodontal pocket.', 'interventionNames': ['Procedure: scaling and root planing (SRP) + PDT']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'scaling and root planing (SRP) + PDT placebo', 'description': 'Patientes will receive periodontal treatment (scaling and root planing - SRP) with the ultrasound. The SRP will be done in one session. The PDT placebo wil be done using an agent with the same vehicle as that of the methylene blue to mimic irrigation with the photosensitizer; the laser will be switched off at the time of application.', 'armGroupLabels': ['scaling and root planing (SRP) + PDT placebo']}
- {'type': 'PROCEDURE', 'name': 'scaling and root planing (SRP) + PDT', 'description': 'patients will receive the same scaling and root planing treatment that placebo group.However the PDT will be done only on one side of mouth using methylene blue 0.005% .The red laser diode (λ = 660 nm) will be applied with an output power of 100mW . The laser head will be positioned in direct contact with the pseudo periodontal pockets.', 'armGroupLabels': ['scaling and root planing (SRP) + PDT']}

Primary Outcomes:
- {'measure': 'Gingival bleeding index', 'description': 'The periodontal probe will be inserted at all predetermined sites at the gingival margin of all teeth, 30 seconds will be waited and, at the smallest sign of bleeding, the presence or absence of bleeding will be noted. Gingival bleeding will be evaluated at 4 sites (mesiobuccal, distobuccal, mesiolingual, distolingual.The gingival Index will be presented in a percentage (%). The result will be based on the ratio of total sites to sites affected. Results will be considered indicative of gingivitis with ≥ 10% bleeding . It will be assessed at baseline and 30 days after treatment.', 'timeFrame': 'through study completion on average of one year'}

Please estimate the sample size based on the assumption: 
Type 1 error of 0.2, 95% confidence level, and a 20% drop-out rate.
2.1
        Calculation of sample size
        To achieve an effect size =â0.40 between two groups (conventional treatment and PDT), for the difference in the amount of bacteria present in the crevicular fluid of participantstreated with scaling and those treated with PDT, assuming a type 1 error of 0.2[1] and 95% confidence level, the total sample size will be 34 participantsdistributed into 2 groups. The sample calculation was performed in Excel, based on the calculation formula described by Kadam and Bhalerao. Considering a 20% drop-out, 3 extra participantswill be inserted into each group, if there is said drop-out this will provide a final sample of participants per group.[32]
        To ensure participantsâ adherence to the research, the steps will preferably coincide with the participants's return visits to their routine orthodontic appliance maintenance. Participants uptake will occur during routine consultations with the orthodontist.