ABSTRACT
The use of plasma-sprayed hydroxyapatite (HA)-coated implants in the clinics over the past 10 years has initiated substantial controversy in the field of dental implantology. One of the greatest concern about the use of plasma-sprayed HA coated implants is the general lack of long-term documentation on implant survival. Over the years, vast amount of in vivo research has indicated biocompatibility with HA-coated implants and a better performance when compared to noncoated titanium (Ti) implants. The better performance of plasma-sprayed HA implants is because of rapid initial osseointegration, and the high bone contact and interfacial strength between implants and bone.[1-4] However, the advantages of plasma spraying HA on Ti implants are mired in considerable controversy owing to a lack of correlation between implant success and the specific surface properties of HA. It is known that the properties of HA coatings are altered during the coating process. Although, there is a lack of appreciation for the effects of altered HA coating properties on bone cell activity, the rationale for coating implants with HA grew out of the desire to combine the strength of Ti implant with a bioactivity HA surface.[5-10] However, there are problems with plasma-sprayed HA coatings, including variation in the coating-metal adhesion strength, nonuniformity in coating thickness between vendors, alteration in structural and chemical properties during the coating process, and nonuniformity in coating density.[1-10] As a result of these problems, there is controversy over whether or not HA coatings are beneficial to implant success. However, these problems are not shortcomings inherent in the rationale for
HA coating, but rather in the plasma spray technology currently used for depositing HA coatings on implant surfaces. This article will provide the current research on plasma-sprayed HA implants, including some plasma spraying techniques, in vivo study, clinical applications, as well as future developments.
