Quantification of bone resorption in the interforaminal region of the atrophic mandible.

PURPOSE

This anatomic study was undertaken to examine the effects of atrophy on bone quantity and quality in the mandibular interforaminal region.

MATERIALS AND METHODS

Three sections were made from each jaw studied, and each section was measured by means of a morphometric software program (Artma-Biomed, Vienna, Austria). The mandibular specimens were grouped according to the classification of Cawood and Howell and also according to that of Lekholm and Zarb.

RESULTS

The macromorphometric measurements revealed that mandibular atrophy may cause the loss of up to 60% of the original bone mass. As the maximum width remained relatively consistent in all jaw sections, it can be assumed that the reduction in total area of each jaw section results from a reduction in mandibular height. The compact and cancellous bone portions were equally affected by resorption. The assessment of bone quality showed that most mandibles displayed a thick cortical compartment, especially inferiorly and lingually, with variations in the amount of cancellous bone. There was a clear predominance of bone types 2 and 3.

DISCUSSION AND CONCLUSION

The interforaminal region of the mandible appears to be the site of choice for implantation, since it can be expected that the bone structure is well suited to provide the necessary stability even in severely atrophic mandibles. As the degree of alveolar ridge resorption does not depend on the patient's age but on the time elapsing postextraction, implants should be placed as soon as possible after tooth loss in order to avoid excessive resorption.