Abstract
Hydroxyapatite (HA) is a strong bonding bioactive implant material for “biointegration” of an apatite implant to bone. It is reported that the period of bone healing after HA implantation is shorter than that after titanium implantation, and the HA implant can be applied in case of low bone density. On the other hand, it is said that the marginal bone is absorbed rapidly when periimplantitis of HA occurs. There is little information about the interaction between the HA and oral bacteria in spite of the large number of studies that have been done on the implant-bone/cell interface. The purpose of this study was to clarifyperiimplantitis of HA implants from the standpoint of microbiology.
Firstly, failure dHA implants (Apaceram®2-Piece Implant type S, Pentax), which were brought to our hospital, were used as samples and the surface of the implants were examined by a scanning electron microscope (SEM). The HA surface was rough and most plaque formations were located on the neck of the implant, and few were on the bottom of the implant. The plaque consisted of cocci and rods, including slight filamentous bacteria. Few spirochetes were observed.
Secondly, the initial adherence of Streptococcus constellatus ATCC 27823T to dHA and titanium alloy (Ti) in vitro was investigated. Bacterial cells attached to dHA were about twiceas many as those attached to Ti. The adherence to saliva-treated (ST)-Ti was about 20% higher than that to nontreated (NT)-Ti. The adherence to ST-dHA was notdifferent from that to NT-dHA. As the duration for acid-treatment to HA reached about 20 sec, the adherence to HA increased rapidly, leveling off at 16%.
