Regular Home Use of Dual-light Photodynamic Therapy on Oral Health in Adolescents Undergoing Fixed Orthodontic Treatment

Inclusion Criteria: * age of 15-18 years old * starting fixed orthodontic treatment * good oral hygiene according to the dentist's assessment * absence of periodontal disease and lack of oral lesion * signed a written consent form, including information to caregivers. Exclusion Criteria: * any chronic diseases * medications that could influence the study (according to the dentists' assessment) * active caries or a supposed high risk of caries * gingivitis (bleeding on probing \>10%) * use of antiseptic mouthwashes * smoking * use of antibiotics or anti-inflammatory therapy within 3 months before entering the study or during the study * unable to cooperate with the protocol. * pregnancy or lactation