Histopathologic Findings in Explanted Osteo-odontokeratoprosthesis

PURPOSE.To report the histologic findings in three explanted osteo-odontokeratoprosthesis (OOKP) laminae. METHODS.The osteodental lamina of patient 1 with linear IgA bullous dermatosis had to be explanted 15 months after OOKP surgery because of permanent leakage after the resorption of the inferior half of the bone/dentin complex. Patient 2 underwent surgery because of corneal blindness caused by ocular pemphigoid. The remnants of the osteodental lamina were removed after a spontaneous loss of the optic cylinder 30 months after surgery. Patient 3 showed decentration of the optic cylinder 14 years after OOKP surgery was performed because of severe bilateral chemical burn. After intraoperative detachment of the optical cylinder from the broken lamina, the keratoprosthesis had to be completely removed. All specimens were fixed, decalcified using electrolysis, sectioned, and stained with hematoxylin and eosin. RESULTS.All three laminae showed some degree of transformation and resorption of dentin and bone tissue. An inflammatory reaction could be observed in the laminae of patient 1 and 2. Downgrowth of keratinizing squamous epithelium and a reduction of bone tissue and dentin was found in patient 1. Most of the osteodental lamina of patient 2 had been replaced by connective tissue. No signs of acute or chronic inflammation could be found in patient 3. The optical cylinder was surrounded by a thin layer of connective tissue that was enclosed by a layer of woven bone. Dentine was found in just one half of the specimen, adjacent to a partly preserved alveolar-dental ligament. CONCLUSION.No conclusive explanation for the dissolution of the osteodental lamina in some of the patients can be offered at this time, although a few different mechanisms such as epithelial downgrowth and/or localized inflammation seem to play a pivotal role. Conversely, the preservation of the alveolar-dental ligament seems to be essential for the maintenance of the integrity of the OOKP.