Abstract
BACKGROUND: Interdental spaces are particularly susceptible to biofilm accumulation and gingival inflammation, which contribute to periodontal diseases and their systemic associations. While interdental brushes (IDBs) are recognized as the most effective method of interdental cleaning, their efficacy depends on proper adaptation to the interdental space. Calibration with a colorimetric probe may enhance their effectiveness and comfort. However, evidence directly comparing calibrated and noncalibrated IDBs, especially in young adults, a key target group for preventive strategies, remains limited. The Hygiene of Interdental Junctions in Adults (HIJA) trial was designed to address this gap. OBJECTIVE: This protocol aims to compare the clinical, microbiological, and acceptability outcomes associated with calibrated versus noncalibrated IDBs in young adults, focusing on interdental inflammation, periodontal indices, and microbiota composition. METHODS: The HIJA trial is a monocentric, randomized, controlled, single-blind, and parallel-arm study. Overall, 50 healthy, nonsmoking adults aged 18-30 years will be randomized (1:1) to receive either calibrated or noncalibrated IDBs. Participants will perform daily interdental cleaning in addition to conventional toothbrushing for 3 months. The primary outcome will be the reduction in interdental inflammation, expressed as the change in bleeding on probing at 3 months. Secondary outcomes will assess differences in interdental microbiota composition (16S ribosomal RNA sequencing), periodontal indices (plaque index, gingival index, probing depth, and clinical attachment loss), and user acceptability measured through the Theoretical Framework of Acceptability questionnaire at 1, 2, and 3 months. RESULTS: The HIJA trial will generate evidence on whether calibrated IDBs provide additional benefits over noncalibrated brushes in reducing interdental inflammation and improving oral health in young adults. CONCLUSIONS: HIJA findings could contribute to the implementation of clinical guidelines and preventive strategies for interdental hygiene in daily practice.