Complex sentence: Bivalves typically have two valves that are joined by a ligament, and often articulate with one another using structures known as dentition or "teeth" which are situated along the hinge line.
Split into simpler sentences: Bivalves typically have two-part shells, two valves, that are joined by a ligament. The two valves usually articulate with one another using structures known as "teeth" which are situated along the hinge line.