The effect of cranio-maxillofacial osteotomies and distraction osteogenesis on speech and velopharyngeal status: A critical review

Objectives: To review the impact of maxillary advancement by orthognathic surgery and distraction osteogenesis on speech and velopharyngeal status based on the literature of the past 30+ years, to review the methods employed in previous studies to explain discrepancies in results, and to make recommendations for future studies. Method: Thirty-nine published articles on the effect of cranio-maxillofacial osteotomies and distraction osteogenesis on speech and velopharyngeal status were identified and were systematically analyzed. A total of 747 cases of cleft and noncleft patients were selected, including craniofacial deformities and syndromes mainly involving maxillary hypoplasia. Results: Findings varied. Many studies found that surgery had no impact on speech and velopharyngeal status. Some reported worsening only in patients with preexisting velopharyngeal impairment or those with borderline velopharyngeal function before surgery. There was no clear difference in outcome between distraction and conventional osteotomy, although there have been few systematic comparisons. There was great variation among reviewed studies in the number of subjects, speech sample, number and type of listeners, speech outcome measures, and timing of postoperative assessment. Few studies employed reliability measures. Conclusion: None of the 39 reviewed studies compared conventional osteotomy and distraction by including both groups in a single study. Randomized controlled trials with-adequate number of subjects and follow-up duration are needed.