The alveolar process of the edentulous maxilla in periodontitis and non-periodontitis subjects

Background: Early implant failures may document that the bone tissue or the wound-healing process following installation surgery was compromised. Subjects who have lost teeth for periodontal reasons exhibit more earlier implant failures than subjects who had experienced tooth loss for other reasons. Aim: To describe the tissue of the fully healed extraction sites in subjects who had lost teeth as a result of periodontitis or for other reasons. Material and methods: Thirty-six otherwise healthy, partially dentate subjects with fully healed edentulous portions in the posterior maxilla were included. Nineteen of these subjects had lost teeth because of advanced periodontitis (group P) and 17 for other reasons (group NP). Using a trephine drill, a 4-6mm long hard tissue specimen was harvested. The biopsies were decalcified, embedded in paraffin, sectioned, stained and examined. Results: The edentulous posterior maxilla was comprised of 47.1 +/- 11% lamellar bone, 8.1 +/- 7.1% woven bone, 4.3 +/- 3.1% osteoid and 16.5 +/- 10.4% bone marrow. There were no significant differences in the tissue composition of post-extraction sites of (i) P and NP subjects and (ii) premolar and molar sites. Conclusion: More than 50% of the edentulous maxilla was comprised of mineralized bone (lamellar and woven bone). The bone trabeculae frequently appeared to have a random orientation. The direction of the trabeculae rather than the lack of mineralized bone tissue may explain the clinical impression that the bone in the posterior maxilla provides limited resistance to mechanical instrumentation.