Cleft Lip and Palate Associated With the Phonetic Function: A Systematic Review

Cleft lip and palate (CLP) are congenital malformations of the craniofacial complex that disrupt the structure and function of the stomatognathic system, particularly articulation and phonation. These anatomical abnormalities affect pressure consonants and resonance balance, often resulting in impaired phoneme production and varying degrees of nasality. Understanding how CLP affects speech is essential for guiding rehabilitation and designing targeted early interventions. This systematic review aimed to identify the most frequently affected speech phonemes and determine the degree of nasality in patients with CLP. A literature search covering the last 10 years (2015-2025) was conducted using PubMed, SciELO, and Scopus. A total of 484 articles were identified, of which 20 met the inclusion criteria. The most affected phonemes across languages were /k/, /p/, and /t/, all voiceless stop consonants. Most patients exhibited mild nasality; however, a consistent association was observed between delayed reconstructive surgery and increased nasality severity.