Hyperpure chlorine dioxide versus chlorhexidine in intra-oral halitosis (ODOR trial) - protocol of a double-blinded, double-arm, parallel non-inferiority pilot randomized controlled trial.

Introduction: Intra-oral halitosis (IOH) is the most common type of bad breath; its consequences impair quality of life. However, evidence-based treatment protocols and guidelines are lacking. Our aim is to investigate the effectiveness of chlorine dioxide as an applicable complementary treatment modality in IOH after tongue cleaning.

Methods and analysis: The ODOR trial will be a single-center, double-blinded, parallel-group, double-armed pilot randomized controlled trial with a non-inferiority design. The efficacy of hyperpure chlorine dioxide will be compared to chlorhexidine mouthwash. We plan to investigate the short-term effects of the intervention over a 3-h period. The primary endpoint will be changes in organoleptic test scores. At the end of the pilot investigation of the first 30 patients each, sample size calculation will be performed. If feasible, the investigators will continue the study by enrolling more patients.

Trial registration: The trial has been registered at ClinicalTrials.gov (NCT06219226).