The osteogenic activity of bone removed from healing extraction sockets in humans.

Cores of bone from healing extraction sites were studied at time intervals of 4, 6, 8, 10, 12 and 16 weeks. The results revealed that between 4 and 8 weeks proliferation of cellular and connective tissue elements occur within the healing socket. Islands of new bone with an osteoid seam surrounded by osteoblasts are present within the connective tissue. From 8 to 12 weeks the bone undergoes maturation and forms a trabecular pattern. Although less pronounced, and osteoid seam is still present and osteoblasts occur in fewer numbers. By 12 to 16 weeks the bony trabeculae are mature with very little osteoid and few osteoblasts. This bone resembles alveolar trabecular bone. Two phases of bony regeneration are apparent from the present study. From 4 to 8 weeks there is a progressive osteogenic phase with proliferation of osteogenic cells and immature bone formation. From 8 to 12 weeks the osteogenesis slows down and the trabeculae mature and increase in volume. From 12 to 16 weeks the bone appears to stabilize with an established alveolar trabecular bone being present. Very little osteogenesis occurs as evidenced by minimal or no osteoid seam with only occasional osteoblasts. It is apparent that in the period between 8 and 12 weeks a substantial quantity of relatively mature well formed bone is present which contains osteoblasts and an osteoid seam. This appears to be an optimal time period to secure bone from a healing extraction site for grafting purposes.

Palatal exostosis in the molar region.

Six hundred and eithty-one dried human skulls of different ethnic backgrounds or localities were examined for the presence of palatal exostosis in the molar region. Of these samples, 276 (40.53%) exhibited some form of palatal exostosis. Chi-square analysis shows that the occurrence of exostosis is: (a) Dependent upon the locality in which the subject lives; (b) Influenced by age; (c) In any age group, dependent upon the locality; (d) Dependent upon the type or class of exostosis; (e) In any type, influenced by locality. The result of this investigation may become clinically important. It suggests, for the clinicians in the field of periodontics, certain diagnostic guidelines for treatment planning of periodontal surgical procedures in the palatal molar region. Thus, an awareness of the patients' ethnic background, as well as age, may be essential in order to minimize or avoid unnecessary postoperative healing complications.