Histological Evaluation of Bone Ingrowth around Titanium and Hydroxyapatite-coated Titanium Implant in Dogs

Yoon, Taek Rim; Jung, Sung Taek; Yang, Sun Ju; Yoo, Kyung Yeon; Lee, Seung Gi; Son, Yoon Ho

Abstract

Since the concept of osseointegration has been introduced, a lot of researches were performed to achieve stronger fixation of the implant. In this study, we tried to find the different pattern of bone ingrowth after implanting pure titanium implant and Hydroxyapatite coated titanium implant in dogs. Four typed of cylindrical titanium implants (diameter 6 mm, length 1 mm) were inserted in the distal femur of adult dogs. The histological examination was done at postoperative 2, 4, 8, and 12 weeks. There was no foreign body reaction at contact site and all implants kept direct contact with bone tissue. In the light microscopic finding, after 2 weeks, the cases with Hydroxyapatite-coated Implant (HAP) showed greater formation of immature woven bone in comparison to Titanium implant. After 4 weeks, Hydroxyapatite-coated Implant (HAP) showed more mature lamellar bone. After 8 and 12 weeks, most of the woven bone was transformed into mature lamellar bone. The fluorescence microscopic finding, after 2 weeks, revealed calcein green fluorescence around implants in all cases and it was more prominent in the cases with Hydroxyapatite-coated Implant (HAP). After 4 weeks, the center of trabecula gave out green fluorescent light, the corner of them showed red fluorescent light, and they were more prominent in the cases with Hydroxyapatite-coated Implant (HAP). After 8 and 12 weeks, green fluorescence disappeared gradually, red fluorescence appeared for the most part, and there was no difference in each cases, especially in 12 weeks. As a result, we support the concept that Hydroxyapatite-coated Implant (HAP) induces faster bone ingrowth in 4 weeks than Titanium implant, and that it may be more profitable for early bone ingrowth and implant stability.