Histologic evaluation of calcium phosphate coated endosseous implants prepared by spark discharge oxidation : a long-term study in the sheep

The present study was designed to evaluate the in vivo degree of bone apposition of experimentally coated endosseous implants. Cylindrical rods of commercially pure titanium were prepared by means of electrochemical spark discharge oxidation. The created highly textured titanium oxide layers of two implant types were coated with bioceramics during the oxidation process (type 1 and type 2), whereas a third implant was successively coated by hydroxyapatite-(HA-)gel immersion successive to the oxidation process (type 3). Experimental bioceramic coatings consisted of pure hydroxyapatite in type-1-implants, biphasic calcium phosphate (B-CaP, i.e. 70% tricalcium phosphate to 30% HA) in type-2-implants, and the post oxidation applied pure HA in type-3-implants. Two conventional surface designs produced by titanium- (type 4) and HA-plasma-spraying (type 5) served as control. <br>The study utilized a unilateral transcortical costal model in 6 house sheep. Histomorphologic and histomorphometric comparisons were made after healing times of 6 and 12 months. Evaluation demonstrated a largely completed osseointegration already after 6 months. No inflammatory cell infiltrate or adverse tissue reaction was present. All coatings served as favourable scaffolds for osseoconduction. Delamination of the coating layers was a frequent finding in the experimental specimens, mostly seen in type-3-implants (HA-gel-coated post oxidation). <br>Histomorphometric data was obtained from the cortical and cancellous portions of the implants, separately. A bone apposition index (AI), defined as the percentage of the total implant surface covered with bone, was calculated additionally. The bone appositional index after 6 months healing time ranged from 78.9% to 86.1% in cortical bone and from 69.7% to 81.4% in cancellous sites. AI at implantation time of 12 months was 84.0%–88.5% for cortical and 58.5%–77.6% for cancellous bone, respectively. Statistical analysis revealed no differences between 6 and 12 months AI-values. For both observation periods, no significant superiority of any coating type was traced. However, after pairwise comparison, the cancellous portions of the type-3-implants (HA-gel-coated post oxidation) and the conventional type-5-implant coatings (HA-plasma-sprayed) revealed significantly higher values than type-1-implants coated during oxidation (p < 0.05). This tendency was also observed in the values for the total AI. AI-values for cancellous portions and the total appositional index were highly correlated (r = 0.95).

Author dc:creator

• Goriwoda, Walter

Contributors dc:contributor

• Schmelzeisen, Rainer

• Osseointegration
• Osteokonduktion
• TCP
• Trikalziumphosphat
• Implant
• coating
• calcium phosphate
• in vivo

Repository record source_url

https://freidok.uni-freiburg.de/data/1912

OAI identifier oai:identifier

oai:freidok.uni-freiburg.de:1912