Light and transmission electron microscopic studies following frontal sinus obliteration with ionomer cement in cats

Osteoplastic frontal sinus surgery in combination with sinus obliteration can be performed for various indications, including chronic sinusitis, frontal sinus trauma and removal of osteomas. In an experimental study using cats, the mucous lining of the frontal sinus was removed, the nasofrontal duct sealed with semifluid ionomer cement and the cavity filled with Ionogran, a solid and porous bone substitute based on ionomer cement. Histological investigations up to 1 year after surgery showed increasing sinus obliteration by regenerating bone, starting from the sinus wall, and formation of connective tissue between the cement grains. There was no evidence for mucosal regeneration. Electron microscopic examination of the interface between the cement and connective tissue revealed mesenchymal cells, collagen fibers and areas of mineralization in close contact with the implant material. Newly formed connective tissue matrix in intimate contact with the cement was a good indication for biocompatibility of the material and is a possible explanation for the implant's solid adhesion to bone. The present findings indicate that Ionogran is a suitable alloplastic material for experimental frontal sinus obliteration in cats.