What is the likely cause of pain on swallowing when a removable partial denture (RPD) is removed?

Pain on swallowing after the removal of a removable partial denture (RPD) can be attributed to lingual impingement. This occurs when the clasps or major connectors of the RPD make contact with the lingual tissues of the tongue or the floor of the mouth, causing irritation or soreness. When the partial denture is in place, the tissue may become accustomed to the pressure and adaptation that the denture provides. Upon removal, the sudden loss of support can expose any pre-existing irritation, and the inflammation of the oral tissues may become more pronounced, leading to pain while swallowing.

The other options describe different issues that can occur with an RPD, but they do not specifically lead to the pain described in this scenario. Overextension of the denture base can cause discomfort, but it typically contributes to pain during wear rather than after removal. Incorrect alignment would generally lead to discomfort while the RPD is in use or fitting issues rather than specifically affecting swallowing after its removal. Pulpitis is related to issues inside the tooth itself and would not cause pain specifically on swallowing after the removal of an RPD. Thus, lingual impingement is most directly associated with the symptoms presented in the question.