抄録
471 cases (374 patients) were evaluated as to alveolar bone height of posterior edentulous in maxilla using panorama X-ray films. Those cases were classified not only several modality of edentulous type which were 4567, 567, and 67 but also partially and completely edenturism. Those cases were measured by the distance from the alveolar ridge to the maxillary sinus floor and converted by 1.2 magnification in ideal implantation positions 4,5,6,6', and 7 (the first molar was divided into two points), respectively. Then the possibility ratio of implant treatment, which decided of alveolar height over 11.0 mm, was examined in each type of edenturism. In addition, the form of the maxillary sinus floor was investigated. The results were as follows.
1. The patients'mean age was 65.6 years (range 23 to 94), and classification of edentulous type was as follows: 4567 was 298 cases, 567 was 78 cases, and 67 was 95 cases.
2. The mean distance from the sinus floor to the alveolar ridge was as follows:4 was 14.1 mm (range 0.5 to 38.0), 5 was 10.8 mm (range 0.5 to 34.0), 6 was 8.3 mm (range 0.5 to 28.0), 6' was 7.8 mm (range 0.5 to 22.0), and 7 was 10.0 mm (range 0.5 to 28.0).
3. The possibility ratio for implant treatment was as follows:4567 was 37.9%, 567 was 33.3%, and 67 was 25.3%.
4. The investigation about sinus floor forms and the possibility ratio was as follows: mono-concave type was 312 cases (possibility ratio 37.8%), two-concave type was 99 cases (32.3%), three-concave type was 37 cases (16.2%), and four-concave type was 23 cases (30.4%).
In the above-mentioned, most of posterior edentulous cases in the maxilla had inadequate alveolar bone height for implant treatment. We should more often consider some countermeasures to obtain adequate bone volume in this region.
