[Significance of the height and width of the alveolar ridge in implantology in the edentulous maxilla. Analysis of 95 cadaver jaws and 24 consecutive patients].

Consideration of alveolar profiles and clinical experience demonstrate that the transversal dimension has been neglected in dental implantology so far. For a comprehensive evaluation of the impact of alveolar bone height and width, 95 edentulous bony maxillae with standardized, measured, and classified cross-sections were analyzed. With four types of implants (minimum length, 10 mm), 1076 insertions were simulated at 269 cross-sections and evaluated with regard to type of implant, position of cross-section, and class of atrophy. Similar evaluation was carried out in the clinical part of the study on 24 consecutive patients with edentulous maxillae. Implant insertion could only be simulated in 35% of the cadaver cross-sections, but had been expected in an additional 4.5% based on their sufficient bone height; length reductions were necessary in another 6%. These results depended largely on the class of atrophy. Anterior cross-sections offered better conditions than posterior ones. In contrast, implant insertion was impossible in all 24 patients. Height was primarily inadequate in 22 patients, and in two patients with sufficient bone height inadequate transversal dimensions were only recognised intraoperatively. These results allow a quantification of the impact of vertical and transversal maxillary alveolar bone dimensions. This impact primarily depends on bone height, but even with sufficient height, reductions of implant length often become necessary. Both for the cadaver maxillae (12% of the cross-sections with expected implant insertion) and for the patients (8%), alveolar profiles remain in which height measurement alone leads to incorrect assessment and may even result in the interruption of precisely planned surgical procedures. The complexity and expense of implant-borne rehabilitation and the consequences resulting from incorrect preoperative planning therefore generally justify extended cross-sectional diagnostic measuring.