The polyacetyl homopolymer polyoxymethylene (Delrin) has been used successfully in orthopedic joint replacements. The efficacy of using Delrin as mandibular condylar replacement in growing children and to determine the effect on fossa remodeling of such replacement, condyles were removed unilaterally in six papio anubis baboons 11/2 to 2 yr of age. The condyles were then replaced with a total prosthetic Delrin condyle attached to a titanium mesh. Specimens retrieved on sacrifice at two, four, and six mo indicated not only complete acceptance of the Delrin but also formation of bone between the middle cranial fossa and the roof of the glenoid fossa. Total bony integration of the Delrin occurs leading to the formation of a new condyle growth center provided that effective orthopedic forces are maintained to distract the condyle slightly from the glenoid fossa base. This work could project the possibility of a totally new concept of total joint replacement in children having various types of deformities such as hemifacial microsomia.