OSSEOINTEGRATION IN SINUS-FORMING BONE

Osseointegration, using bone-anchored titanium fixtures, is a well-est ablished technique for both intraoral and craniofacial prosthetic reha bilitation. The use of this technique in children can be complicated b y craniofacial growth and sinus development. This study evaluates the effects of sinus formation and growth on the fate of osseointegrated t itanium fixtures in the growing porcine model. At 3 weeks of age, six Landrace White cross male pigs had a 3.15 X 3.0 mm titanium fixture (N oblepharma) inserted into their right frontal bone where the right fro ntal sinus would subsequently develop. Preoperative CT scans with thre e-dimensional reconstructions were used to determine the insertion sit e. To follow the effects of growth and sinus formation, CT scans with three-dimensional reconstructions and cephalometric radiographs were t aken at 1, 3, 6, and 9 weeks postoperatively and at sacrifice. The pig s were sacrificed serially, and direct osteometric measurements were t aken to determine skull symmetry. All skulls were sectioned, and osseo integration was determined clinically, radiologically, and histologica lly with light and scanning electron microscopy. Five of the six fixtu res osseointegrated. There were no apparent growth disturbances due to the fixtures. As growth progressed, the osseointegrated fixtures subm erged into the frontal bone in a posteroinferior direction to become c ompletely intraosseous 14 weeks after insertion. As the frontal sinus pneumatized, the futures remained osseointegrated, but progressive amo unts of the fixtures became exposed in the sinus. From this study it w ould appear that osseointegrated titanium fixtures do not have any eff ect on calvarial growth and gradually submerge into the growing bone. As sinus development ensues, the fixtures remain integrated but become partially exposed within the sinus. These findings have implications for the use of such futures in children.