Long-term outcome after obliteration of the cat frontal sinus with ionomer bone substitute. II: Histomorphometric measurements

Abstract

Stenosis or occlusion of the nasofrontal duct with subsequent recurrent frontal sinusitis or mucocele formation may require osteoplastic surgery in combination with frontal sinus obliteration. To study its suitability as an implant material in sinuses, granular ionomeric cement was applied for frontal sinus obliteration in 15 cats. The frontal sinus specimens were processed for histological studies after 1, 3, 6, 12, and 24 months, respectively. To obtain quantitative data from the histological sections, areas of osteoid, connective tissue, and implanted ionomeric cement were measured with a computerized digitizing pad and compared to the total area of each frontal sinus. To our knowledge, histomorphometrical analysis of mesenchymal tissue reactions in close contact to an alloplastic material inside the frontal sinus cavity has not been described to date. Bone regeneration, starting from the sinus wall, was detected as early as one month after implantation. The quantitative data for osteoid indicated increasing osteoneogenesis and decreasing connective tissue growth inside the sinus cavity over the period of investigation. Two years after surgery, the osteoid represented 43.5%, the connective tissue 10.7%, and the ionomeric cement 45% of the whole cavity. The implanted cement did not show a significant degradation after two years. The results of the present study demonstrated the biocompatibility and biostability of the ionomer-base microimplant.