Staining of teeth is least commonly associated with cleft lip and palate as it is primarily related to extrinsic factors such as poor oral hygiene, dietary habits, or exposure to certain medications, rather than the developmental disturbances seen in cleft conditions. In contrast, hypodontia, supernumerary teeth, and malpositioned teeth directly result from the disrupted odontogenesis and altered maxillofacial anatomy caused by clefts. These dental anomalies are intrinsic to the developmental defect, whereas staining is an acquired condition and not a direct consequence of the cleft itself.

Reference: Neville et al., Oral & Maxillofacial Pathology, 4th Edition.