Differential craniofacial skeletal changes after postnatal experimental surgery in young and adult animals.

To find answers to the many questions about abnormal postnatal growth and change of the craniofacial skeleton, a series of surgical experiments was carried out in both young and adult animals. The purpose of this review is to relate this information to basic ideas about bone change and some local factors which may or may not affect skeletal changes. No gross regional deformity was noted after resection of sutures in young animals. The growth of bone at sutures was secondary or compensatory to other factors. In young animals, increase in size of the nasal or orbital cavities decelerated considerably after resection of either nasal septum or orbital tissues. With an increase in volume of orbital contents, orbital volume increased. These prominent gross changes in young animals were not noted in adult animals after resection of nasal septum, enucleation of the eye, or intrabulbar injection of silicone. After unilateral resection of the mandibular condyle in both young and adult monkeys, an extreme unilateral facial skeletal deformity developed. The important factor apparently was loss of integrity of the temporomandibular joint rather than loss of a growth site. The craniofacial skeleton, a three-dimensional mosaic of bones and cavities, develops as a result of the synchronous coordination of the differential activities at various sites. The dynamics of the growth and change are a fascinating, complex, incomplete chapter of biology. An understanding of factors that may or may not influence the craniofacial skeleton in both young and adult animals can aid diagnosis and surgical treatment.