Biologic response to passive dissolution of titanium craniofacial microplates

The effect of anodization on passive dissolution of titanium was studied by measuring titanium levels in peritoneal leukocytes and tissues of laborato ry animals with titanium plates implanted into the peritoneal cavity. Fifte en Sprague-Dawley rats were assigned randomly to three treatment groups of five animals. One group served as controls, the other two groups had an ano dized or an unanodized implant placed in the left paracolic gutter. Periton eal lavage samples and blood samples, organ tissues and tissue surrounding the implants, were removed for histologic examination and titanium levels. Titanium was not detected in any distant organs or in the peritoneal lavage fluid. The capsular tissues surrounding the implants contained titanium at levels ranging from 2610 to 16786 ng/g for unanodized plates, and 888-5933 ng/g for anodized plates. The titanium levels within the peritoneal leukoc ytes of animals with unanodized implants were significantly elevated (P = 0 .01) over time, as compared with controls. The level of titanium in the per itoneal leukocytes of animals with anodized implants was not significantly elevated when compared with controls. Titanium levels in the trace range, a s measured in the capsular tissues, are likely a result of corrosion. Surfa ce treatment of titanium by anodization reduces passive dissolution. (C) 19 99 Elsevier Science Ltd. All rights reserved.