Tooth whitening is a procedure that has been increasingly requested by patients around the world, whether at home or in office bleaching. Tooth sensitivity is the main side effect of bleaching. It have a great power to interfere negatively in the quality of life of those affected. According to the literature, about 51% of people who had at-home bleaching developed postoperative sensitivity.

The objective of this clinical, randomized, double-blind study is to evaluate the effectiveness of the association of casein phosphopeptides-fluoridated amorphous calcium phosphate with photobiomodulation in the treatment of tooth sensitivity after home bleaching, with 22% carbamide peroxide and also evaluate the effectiveness of at home bleaching through color analysis.

For develop this study, 50 patients will be selected, with no previous history of sensitivity, aged between 18 and 30 years. They will be divided into four treatment groups: PLACEBO group; CPP-ACPF group; LASER group; LASER+CPP-ACPF group.

Home bleaching treatment will use 22% carbamide peroxide. Patients should use two hours a day for 21 days. The desensitizing treatments will be applied in four moments, according to the group of each patient: before starting the bleaching treatment; after one week of the bleaching treatment; after two weeks of whitening treatment and after three weeks of whitening treatment.

Sensitivity will be assessed using a visual analogue scale (VAS), where patients should daily mark their pain level (from 0 to 10) on each side of the arcade. After the 21 days of treatment, they will receive a new VAS, to evaluate if was any sensitivity will occur during 30 days after the bleaching treatment.

In parallel with bleaching treatment and sensitivity treatment, the color analysis of teeth 13, 11, 21 and 23 will be performed, with the Vita Easyshade Advance 4.0 spectrophotometer, to monitor the bleaching performance, in each week. The first one will occur before starting the bleaching treatment (baseline) and a new measurement will be performed every week, together with the application of treatments for sensitivity.

The collected data will be tabulated in an Excel Microsoft Windows 2010) spreadsheet and analyzed in the Jamovi 1.6.23 (The Jamovi Project, 2020) software. For inter- and intra-group analysis of sensitivity values, the Repeated Measures statistical test will probably be used. For all statistical analyses, a significance level of 5% will be adopted.

Tooth whitening is a procedure that has been increasingly requested by patients around the world, whether at home or in office bleaching. Tooth sensitivity is the main side effect of bleaching. It have a great power to interfere negatively in the quality of life of those affected. According to the literature, about 51% of people who had at-home bleaching developed postoperative sensitivity.

The objective of this clinical, randomized, double-blind study is to evaluate the effectiveness of the association of casein phosphopeptides-fluoridated amorphous calcium phosphate with photobiomodulation in the treatment of tooth sensitivity after home bleaching, with 22% carbamide peroxide and also evaluate the effectiveness of at home bleaching through color analysis.

Fifty patients will be selected, who will be divided into four treatment groups: PLACEBO group (will receive a LASER simulation and a manipulated paste without active ingredient to simulate the CPP-ACPF paste); CPP-ACPF group (will receive the CPP-ACPF folder and a LASER simulation); LASER group (will receive the LASER and a manipulated paste without active ingredient to simulate the CPP-ACPF paste); LASER+CPP-ACPF group (will receive the LASER and the CPP-ACPF folder). As it is a split-mouth study, each patient will receive two different types of treatment, one on each side of the arches, thus, the sample size of each group will be 25 patients (n=25).

The treatment with the CPP-ACPF paste (MI paste plus) will be carried out in the CPP-ACPF and LASER+CPP-ACPF groups, at the following times: before the bleaching treatment (T0), after one week of bleaching (T1), after two weeks of bleaching (T2), after three weeks of bleaching (T3). The application will be made on the buccal surfaces of the teeth, up to the second premolars, with the aid of a microbrush applicator (Microbrush, 3M Espe), for five minutes. Afterwards, patients will be instructed to spit out the excess and avoid ingesting anything for 30 minutes. In the PLACEBO group, this clinical protocol will be performed exactly, but using the paste without active ingredient.

The LASER and CPP-ACPF+FBM groups will receive the application of LASER (Therapy EC, DMC, São Carlos, SP, Brazil), using the infrared light spectrum with a wavelength of 808 nm with its active medium of Arsento Gallium and Aluminum (AsGaAl), at three points, one in the center of the crown of the tooth, another in the center of the cervical region and the last one in the incisal region, with the light beam directed apically, from all teeth to the second premolar of each hemi -upper and lower arch. The energy used was 1 Joule per point for 10 seconds.

While the PLACEBO and CPP-ACPF groups received a LASER simulation. The sounds emitted by the laser during its use will be simulated by a mobile application.

All study participants will receive a tube of bleaching agent (Whiteness Simple 22%, FGM, Joinville, Brazil) and will be instructed to apply a drop of the product on the vestibular surface of each tooth on the whitening tray (up to the second premolars) and use for two uninterrupted hours for 21 days.

Sensitivity will be assessed using a visual analogue scale (VAS), where patients should daily mark their pain level (from 0 to 10) on each side of the arcade. After the 21 days of treatment, they will receive a new VAS, to evaluate if was any sensitivity will occur during 30 days after the bleaching treatment.

In parallel with bleaching treatment and sensitivity treatment, the color analysis of teeth 13, 11, 21 and 23 will be performed, with the Vita Easyshade Advance 4.0 spectrophotometer, to monitor the bleaching performance, in each week. The first one will occur before starting the bleaching treatment (baseline) and a new measurement will be performed every week, together with the application of treatments for sensitivity.

The collected data will be tabulated in an Excel Microsoft Windows 2010) spreadsheet and analyzed in the Jamovi 1.6.23 (The Jamovi Project, 2020) software. For inter- and intra-group analysis of sensitivity values, the Repeated Measures statistical test will probably be used. For all statistical analyses, a significance level of 5% will be adopted.

Inclusion Criteria:

• Age between 18 and 30 years;
• Good general and oral health;
• Sound incisors, canines and premolars;
• Prior whitening treatment;
• No hypersensitivity;

Exclusion Criteria:

• Patients undergoing fixed orthodontic treatment;
• Presence of periodontal disease;
• Presence of cracks or fractures;
• Presence of restorations and prostheses in anterior teeth;
• Extensive restorations in molars;
• Presence of gastroesophageal dysfunctions;
• Patients with severe internal dental darkening;
• Presence of exposed dentin.

This is a double-blind study, so that to blind study participants, all treatments were performed in exactly the same way. To simulate the CPP-ACPF paste, a paste without active ingredient was manipulated, but with the same color, texture and smell of the CPP-ACPF paste. To simulate the application of the laser, the operator performed the clinical procedure of applying the laser to three bridges of each tooth, but without activating it. The sound emitted by the laser at each point was simulated by a cell phone application.

To blind the evaluator of the results, he only had access to the patient's name and sensitivity data, but he did not have access to the group to which the participant belonged.