The aim of this clinical study is to evaluate patient satisfaction, bleaching efficacy, and the risk and severity of tooth sensitivity and gingival irritation during home bleaching with 16% carbamide peroxide using conventional (soft) trays or rigid trays. A total of 100 patients will be selected to undergo home bleaching with either soft or rigid trays (n=50). Bleaching will be performed with 16% carbamide peroxide (Whiteness Perfect 16%, FGM, Joinville, SC, Brazil) for 2 hours daily for 3 weeks (21 days). Patient satisfaction will be assessed initially, weekly during the 3 weeks of treatment, and one month after completion of treatment using a questionnaire based on a visual analogue scale (VAS) from 0 to 10. Tooth colour will be assessed at baseline, 1 and 3 weeks during treatment, and 1, 6 and 12 months after treatment using the VITA Easyshade V spectrophotometer and the VITA Classical and VITA Linearguide 3D-MASTER scales (VITA Zahnfabrik, Bad Säckingen, Germany). The risk and intensity of tooth sensitivity and gingival irritation were recorded in a diary using a 0-10 VAS during treatment. Patient satisfaction data were analysed using Student's paired t-test. Colour change will be compared between groups using Student's t-test. The absolute risk of tooth sensitivity and gingival irritation was compared between groups using Fisher's exact test. Relative risk and confidence intervals (CI) were also calculated. The intensity of dental sensitivity and gingival irritation was analysed using Student's t-test for independent samples. The significance level will be set at 5% for all statistical tests.

The purpose of this clinical trial is to evaluate patient satisfaction, whitening efficacy, and the risk and severity of tooth sensitivity and gingival irritation after home bleaching with 16% carbamide peroxide using conventional (soft) trays or rigid trays. In addition, to assess whether there is a difference in patient satisfaction using a 0-10 visual analogue scale with conventional (soft) splints or rigid splints during home bleaching with 16% carbamide peroxide. To evaluate whether there is a difference in whitening efficacy using the VITA Easyshade V spectrophotometer and the VITA Classical and VITA Linearguide 3D-MASTER scales with conventional (soft) splints or rigid splints during home bleaching with 16% carbamide peroxide. To assess whether there is a difference in the absolute risk and intensity of tooth sensitivity using a visual analogue scale from 0 to 10 when using conventional (soft) splints or rigid splints during home bleaching with 16% carbamide peroxide and finally to assess whether there is a difference in the absolute risk and intensity of gingival irritation using a visual analogue scale from 0 to 10 when using conventional (soft) splints or rigid splints during home bleaching with 16% carbamide peroxide.

Inclusion Criteria:

• Patients over 18 years of age.
• Patients with vital teeth without restorations, single crowns, implants and/or bridges on the anterior teeth.
• Absence of dental caries in the teeth to be whitened.
• Patients with satisfactory oral hygiene and periodontal health, not undergoing periodontal maintenance and not using chlorhexidine mouthwashes. Patients with recession and no sensitivity were included.
• The absence of sensitivity was measured by applying air with the syringe of the dental equipment.
• Patients whose canines were at least A2-A3 in colour.

Exclusion Criteria:

• Patients who have already undergone bleaching (less than 5 years).
• Patients undergoing orthodontic treatment.
• Patients with white stains or changes in enamel development or staining.
• Patients with a history of trauma to the anterior teeth.
• Patients requiring internal bleaching.
• Smokers.
• Pregnant or lactating mothers.
• Patients with allergy to any of the bleaching components.
• Patients with oral mucosal changes (desquamative gingivitis, oral lichen planus, leukoplakia, etc.).
• Patients with medical conditions considered by the investigators to compromise the safety of the study or the individual patient.
• Patients with poor oral hygiene.
• Patients with a history of hypersensitivity.

The patients have signed a consent form in which they give their data to the Universidad Rey Juan Carlos, but not to the entire research community. The results obtained will be shared, but not the personal data of the participants, in accordance with the regulations on the protection of personal data, specifically the European Regulation 679/2016, of 27 April, on General Data Protection, as well as the Organic Law 3/2018, of 5 December, on the Protection of Personal Data and Guarantee of Digital Rights.