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This mixed-longitudinal study of edentulous individuals covering 25 years of complete denture wearing revealed a continued reduction of the residual ridges throughout the observation period.

The reduction of the lower ridge was particularly marked, the mean reduction in anterior ridge height being approximately four times as great as the upper ridge.

The magnitude and pattern of alveolar bone loss showed great individual varation.

Correlations between the shape of the mandible and the anterior mandibular bone loss indicated a pronounced resption in subjects with a marked mandibular base bend, and less marked resorption in subjects with a fattened mandibular base. These findings suggest that careful examination of the mandibular shape can provide valuable information on the response of the residual ridges to the wearing of dentures.

Regarding the clinical consequences of the alveolar bone loss it shoud be emphasized that by regular control and prosthetic measures marked instability of the dentures and undesirable changes in jaw oclusal relationships can be prevented. As the rate of resorption is most rapid during the first year of denture wear, regular control during the first year and thereafter at least once a year is advisable.

However, with continuing resorption over years, the prosthetic replacement of the lost tissues will give rise to increasing treatment problems and may cause the patient extreme difficulties in management of the dentures.

The continuing resorption, especially of the lower ridge, therefore, constitutes a serious prosthodontic problem.