Effects of rigid plate fixation and subsequent removal on craniofacial growth in rabbits.

OBJECTIVE To examine the effects of rigid plate fixation (RPF) and subsequent removal on craniofacial growth in rabbits. DESIGN Randomized controlled experiment. SUBJECTS Thirty-two 6-week-old male New Zealand white rabbits. INTERVENTIONS Group 1 underwent exposure of the left nasofrontal suture and midzygomatic arch; group 2, RPF of the left nasofrontal suture and midzygomatic arch areas; group 3, single osteotomy at left nasofrontal suture and double osteotomies at midzygomatic arch with RPF of osteotomies; and group 4, controls. At 11 weeks of age, the RPF was removed. Animals were killed at 20 weeks of age. Linear and 3-dimensional measurements (euclidean distance matrix analysis) were used to evaluate craniofacial regions. RESULTS In comparison with control animals, linear data showed shortening of the left nasal bone in group 3. Groups 1 through 3 also exhibited shortening of the left zygomatic arch, orbital diameter, and anterior midfacial height. Euclidean distance matrix analysis showed significant restrictive shape alterations on both the ipsilateral and contralateral sides in groups 1 through 3. In comparison with animals in which RPF was left in place, linear data showed significant shortening of the orbital diameter in groups 1 through 3 and of anterior midface height in groups 2 and 3. Euclidean distance matrix analysis showed significant restrictive shape alterations on both contralateral and ipsilateral sides. CONCLUSION Rather than preventing restrictive growth disturbances to the growing midface in rabbits, RPF with subsequent removal produces a greater amount of restrictive shape alteration than RPF that is left in place.