Comparison of plasma-sprayed hydroxyapatite coatings and hydroxyapatite/tricalcium phosphate composite coatings: In vivo study

This study aimed to compare biological properties, including osteoconductio n, osseointegration, and shear strength, between plasma-sprayed hydroxyapat ite (HA) and HA/tricalcium phosphate (TCP) coatings, using a transcortical implant model in the femora of canines. After 3 and 12 weeks of implantatio n, the implants with surrounding bone were assessed histologically in undec alcified sections in backscattered electron images (BEIs) under a scanning electron microscope (SEM). After short-term (3 week) follow-up, both coatin gs conducted new bone formation and revealed direct bone-to-coating contact . The HA/TCP coating could not enhance early host-to-coating responses. At 12 weeks, serious dissolution of the HA/TCP coatings evidently occurred. By the new bone healing index (NBHI) and apposition index (AI), we found no s ignificant difference between HA/TCP-coated implants and HA-coated implants throughout all implant periods. At 12 weeks of implantation, some particle s dissociated from the HA/TCP coating were found within the remodeling cana l. After push-out measurements, the shear strength and failure mode of HA/T CP-coated implants were similar to those of HA-coated implants, and no stat istical differences were found between either coating. Consequently, this s tudy indicates that HA/TCP coatings have excellent biological response and may be considered suitable bioactive ceramic coatings for shortterm clinica l use. (C) 2001 John Wiley & Sons, Inc.