LONG-TERM RESULTS FOLLOWING OBLITERATION OF THE FRONTAL-SINUS IN CATSUSING AN IONOMER-BASED MICROIMPLANT .2. HISTOMORPHOMETRY

Background: Stenosis or occlusion of the nasofrontal duct with subsequ ent recurrent frontal sinusitis or mucocele formation may require oste oplastic surgery in combination with frontal sinus obliteration. Metho ds: To study its suitability as an implant material in sinuses, granul ar ionomeric cement was applied for frontal sinus obliteration in 15 c ats. The frontal sinus specimens were processed for histological studi es after 1, 3, 6, 12, and 24 months, respectively. To obtain quantitat ive data from the histological sections, areas of osteoid, connective tissue, and implanted ionomeric cement were measured with a computeriz ed 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 fron tal sinus cavity has not been described to date. Results: Bone regener ation, starting from the sinus wall, was detected as early as one mont h after implantation. The quantitative data for osteoid indicated incr easing osteoneogenesis and decreasing connective tissue growth inside the sinus cavity over the period of investigation. Two years after sur gery, 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. Conclusion: The r esults of the present study demonstrated the biocompatibility and bios tability of the ionomer-base microimplant.