National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

Cleft lip can be a result of failure in which developmental process?

1. Fusion of the maxillary and mandibular process

2. Fusion of the maxillary process with the nasal process

3. Formation of the secondary palate

4. Closure of the foramen cecum

The correct answer is: Fusion of the maxillary process with the nasal process

Cleft lip occurs due to a failure in the fusion of the maxillary process with the nasal process during embryonic development. This process typically involves the merging of these facial structures to form the upper lip and parts of the nasal cavity. When the maxillary processes, which are responsible for the sides of the upper jaw, do not fuse properly with the nasal processes, which contribute to the middle part of the face and the tip of the nose, a cleft lip results. The correct understanding of the developmental processes involved is crucial for grasping the etiology of cleft lip. This condition emphasizes the importance of proper fusion during early embryogenesis, as disruptions in this process can lead to significant congenital anomalies. Other developmental processes mentioned, such as the fusion of the maxillary and mandibular processes or the formation of the secondary palate, play roles in other aspects of facial and oral development but are not directly related to the formation of a cleft lip.