The effects of lip repair with and without soft-tissue undermining and delayed palate repair on maxillary growth: an experimental study in beagles.

Undermining of the soft tissue on the surface of the maxilla at the time of cleft lip repair remains a controversial issue in cleft management. Using 64 eight-week-old beagles, we tested the hypothesis that lip repair with soft-tissue undermining contributes more to maxillofacial growth aberrations than lip repair without these additional procedures. Animals were assigned to four groups: unoperated controls, unrepaired controls, and two experimental groups (with and without undermining). Defects simulating cleft of the lip, alveolus, and palate were surgically created in the unrepaired and experimental animals. At 36 weeks of age, 11 measurements were made directly on the cleaned maxillae. Analysis revealed that all groups with surgically created defects were significantly different from normal; however, animals with undermining exhibited the greatest group deviation from normal. These findings reaffirm our earlier conclusions that undermining of the soft tissue on the surface of the maxilla is detrimental to maxillofacial growth.