If knowing that bacteria and fungus accumulates on your toothbrush bristles overtime isn’t enough reason to replace your toothbrush more often, there are also a number of other risks and uninviting issues involved with not replacing your toothbrush. One risk includes damaging your gums, as old toothbrushes become ineffective with removing plaque from your teeth, which leads to gingivitis. Left untreated, gingivitis leads to infection, which can cause teeth to fall out.
Even more unappealing, you can get sick from overused toothbrushes (see: bacteria and fungus build up), your toothbrush can grow mold, or possibly the least appealing, you can ingest unwanted particles if stored near a toilet.
I don’t know about you, but I’m going to go change my toothbrush right now and schedule a deep cleaning with my dentist.