Oral health in immature permanent teeth with traumatic injuries is particularly vulnerable, and regenerative endodontic treatment (RET) using stem cells from the apical papilla (SCAP) holds potential for root development and tissue regeneration. However, bacterial persistence, especially , poses a challenge to successful treatment outcomes. To address this, we evaluated the probiotic for its co-aggregative and anti-adhesive properties against . An aggregation test demonstrated effective co-aggregation between the probiotic and opportunistic strains. Additionally, flow cytometry analysis revealed that binding to SCAP was significantly reduced when the concentration was nine times higher. To substantiate these findings, an gut model was used, where immunofluorescence imaging and culture-based methods confirmed decreased adhesion at both 1:1 and 9:1 probiotic-to-opportunistic ratios. These results highlight B16 as a promising probiotic strain to improve RET outcomes.