How does unilateral cleft lip develop?

Unilateral cleft lip, the most common form of orofacial cleft, occurs due to a failure of fusion between the maxillary and nasal prominences during embryonic development. It typically affects one side of the lip and can range in severity from a small notch to a complete separation of the lip.

During normal embryonic development, the face is formed by the merging of several prominences or bumps. The maxillary prominences, located on either side of the developing nose, and the nasal prominences, located at the front of the face, fuse together to form the upper lip. If this fusion process is disrupted or fails to occur properly, a unilateral cleft lip can result.

The exact causes of unilateral cleft lip are not fully understood, but it is believed to be a result of a combination of genetic and environmental factors. Genetic factors are thought to play a significant role, as cleft lip and palate have been associated with certain genetic syndromes and mutations, but the specific genetic mechanisms are not yet well-established. Environmental factors, such as certain medications, nutritional deficiencies, maternal smoking, or infections during pregnancy, are also believed to contribute to the development of cleft lip, but further research is needed to fully understand these associations.

Unilateral cleft lip can have various impacts on a person's appearance, speech, and dental health. It may affect feeding and oral hygiene, and may also lead to dental anomalies and malalignment. Treatment for unilateral cleft lip typically involves surgical intervention to repair the cleft and restore the lip's structure, as well as ongoing dental care to address any associated dental issues.