In vivo evaluation of bioactive glass‐based coatings on dental implants in a dog implantation model

Abstract

Although titanium is commonly used as a favorable bone implant material due to its mechanical properties, its bioactive and osteoconductive capacity is relatively low. Calcium phosphate ceramics, predominantly hydroxyapatite (HA), have been frequently used for coating purposes to improve the bioactive properties. In view of the suggested osteopromotive capacity of bioactive glasses (BGs), this study aimed to evaluate the effect of BG incorporation into HA coatings on implant performance in terms of bone contact and bone area. A total of 48 screw-type titanium implants with magnetron sputter coatings containing different ratios of HA and BG (HA, HABGLow, and HABGHigh; n = 8) were placed into the mandible of 16 Beagle dogs. After 4 and 12 weeks, their performance was evaluated histologically and histomorphometrically. Peri-implant bone area percentage (BA%) was determined in three zones (inner, 0-500 μm; middle, 500-1000 μm; and outer, 1000-1500 μm). Additionally, bone-to-implant contact (BIC%) and first bone-implant contact (1st BIC) were assessed for each sample. After 4 weeks, bone-to-implant contact for the HA- and HABGLow-coated groups was significantly higher (P < 0.05) than for the HABGHigh coatings. Mean values for overall BA% showed comparable values for both the HABGLow (58.3%)- and HABGHigh (56.3%)-coated groups. Data suggest that the relative BA around the HA-coated implants (67.8%) was higher, although this was only significant compared to the HABGHigh group. After 12 weeks, all three groups showed similar bone-to-implant contact and no differences in BA were found. The incorporation of BG into HA sputter coatings did not enhance the performance of a dental implant in implantations sites with good bone quality and quantity. On the contrary, coatings containing high concentrations of BG resulted in inferior performance during the early postimplantation healing phase.