Timing of hard palate closure and dental arch relationships in unilateral cleft lip and palate patients: a mixed-longitudinal study.

In a mixed longitudinal study, dental arch relationships of 88 consecutive UCLP patients treated at the Nijmegen Cleft Palate Centre were evaluated using the Goslon Yardstick. On the basis of timing of hard palate closure, the patients were divided into four groups. Mean age of hard palate closure the patients were divided into four groups. Mean age of hard palate closure in group A (n = 18) was 1.5 years, in group B (n = 26) 4.6 years and in group C (n = 18) 9.4 years. In group D (n = 26, no patient older than 10 years) the hard palate was still open. Four stages of dental development were distinguished; deciduous dentition, early mixed dentition, late mixed dentition and permanent dentition. Reproducibility of scoring with the Goslon Yardstick was good for all stages of dental development. No differences in dental arch relationships were found between the four groups. In 86% of the cases, the dental arch relationships of UCLP patients treated in Nijmegen were acceptable. Pharyngeal flap surgery had minor unfavorable effects on dental arch relationships.