How often should I replace this toothbrush, and what signs tell me it's time?

Replace the brush once the bristles begin to spread, flare, or lose their original alignment — usually every two to three months with twice-daily use. Worn bristles cannot maintain the precise tip geometry (triangular tips, square clusters) that lets this design reach between teeth and along the gum line. A quick visual check: hold the brush head sideways; if the bristle tips no longer form a relatively even surface or if you see individual filaments bending outward permanently, cleaning precision has dropped. After illness (cold, flu, oral infection) it's also wise to swap to a fresh brush to avoid re-introducing bacteria. Store upright, uncovered, and allow to air-dry between uses to slow bristle fatigue and microbial growth.