Clinical, cephalometric, and densitometric study of reduction of residual ridges

1. A clinical, cephalometric, and densitometric study of the reduction of residual ridges (RRR) was carried out on 76 edentulous clinic patients (44 women and 32 men) with a mean age 65.2 years (range of 38 to 87 years). 2. In this group of patients with varying periods of time since extraction, a high proportion of maxillary ridges were high and well rounded (Order III), including 50 per cent of those 20 years or more after extraction. In contrast, only 24 per cent of the mandibular ridges were classified as high and well rounded, and of these, 80 per cent were 2 years or less postextraction with 54 per cent classified as knife-edge (Order IV). 3. The rate of total anterior RRR varied between individuals, being immeasurable in 23 per cent and 1 mm. or more per year in 20 per cent. The highest rate in one subject studied over 3 years was 2.2 mm. per year. The average rate was 0.5 mm. per year. 4. The rate of RRR varied between the upper and lower jaws averaging 0.1 mm. per year for the maxillae and 0.4 mm. per year for the mandible. Thus, the average rate for the lower jaw was four times that of the upper. Yet, 9 per cent of the subjects had a higher rate on the maxillae than on the mandible, while the rate was the same in 26 per cent. 5. There was a low correlation between the rate of RRR and several possible cofactors, including sex, age, and bone density. 6. An average rate of anterior vertical RRR of 0.5 mm. per year could represent an average loss of 5 mm. in anterior ridge height (considerably more in some patients) in 10 years, resulting in significant loss of vertical dimension, esthetics, and comfort. Such remarkable changes in millions of edentulous people represent a staggering need for prosthodontic care. 7. New methods of prevention and treatment of this disabling disease must be found.