We need to remove the deposits inside the pipe.
歯の表面に付着物がたまると虫歯の原因になる。
When matter accumulates on the tooth surface, it can cause cavities.
Compound of 付着 (fuchaku, 'adhesion') + 物 (butsu, 'thing'). The exact historical derivation is straightforward; the word follows standard Sino-Japanese compounding patterns.