Final answer:
The nurse encourages the client to see the dentist regularly because of the increased risk for gingival hyperplasia.
Step-by-step explanation:
The nurse encourages the client to see the dentist regularly because of the increased risk for gingival hyperplasia when starting phenytoin (Dilantin). Phenytion is an antiepileptic drug that can cause overgrowth of the gums, leading to gingival hyperplasia.