Bleaching agent containing Hydrogen Peroxide 18% and nano- hydroxyapatite

Bleaching agent containing Hydrogen Peroxide 20% and nano- hydroxyapatite

Bleaching agent containing Hydrogen Peroxide 40% and nano- hydroxyapatite

After the lip retractor (OptraGate, Ivoclar Vivadent, Schaan, Liechtenstein) was placed, the gingival barrier protection (Biowhiten, Biodent Ltd., İstanbul, Turkey) included in the products was applied to the upper and lower arches from premolar to premolar at the beginning of each session and removed after each treatment. The bleaching gels were applied according to the manufacturer and removed after the recommended period with a disposable surgical saliva ejector, cleaned with gauze and washed with air-water spray. Two bleaching sessions were performed at a 1-week interval. Participants were advised to maintain regular oral hygiene by brushing with toothpaste that does not contain desensitizing or whitening ingredients.

HP18 is applied in 5 applications of 10 minutes per session. HP25 is applied in 3 applications of 15 minutes per session. HP40 is applied in 3 applications of 15 minutes per session.

Tooth color was objectively evaluated using VitaTM Easy Shade V spectrophotometer (VITA Zanhnfabrik, BadSckingrn, Germany). The assesment was performed with daylight (10 a.m.to 2 p.m.) considering a 6 mm area situated in the middle section of the labial surface of the upper central incisors. In order to ensure consistency, alginate impressions were taken of the upper dental arches of each participant and stone molds were created. The custom trays were fabricated by using a 2mm Essix plate (Essix C; Dentsply, FL, USA) in a vacuum press machine (Ministar, Scheu, Iserlohn, Nordrhein-Westfalen Germany). 6 mm wide holes were drilled in the middle third of the buccal face of the central incisors on this trays to serve as a guide for using Easyshade V.

To measure tooth sensitivity, participants indicated their discomfort level using a Visual Analog Scale (VAS).23 This scale is represented by a horizontal line measuring 10 centimeters in length. The endpoint of the line labeled "no pain" represents the absence of discomfort, while the opposite endpoint labeled "worst pain" represents the highest level of discomfort.

The OHIP-14 questionnaire was utilized to evaluate the quality of life.24 This questionnaire consists of seven different domains and a total of 14 questions aimed at assessing one's quality of life. Responses to questions were determined by selecting one choice from a Likert scale. The scale included options like never (0 points), rarely (1 points), sometimes (2 points), often (3 points), and always (4 points), each corresponding to a certain number of points. A person's oral health-related quality of life (OHRQoL) is negatively affected when the average value of seven dimensions is higher.