Maximum bite force after the replacement of complete dentures

In complete denture wearers the maximum bite force (MBF) is known to be considerably lower than in dentate people. Low MBF might therefore be an indication of poor denture fit but there is limited evidence on this. Therefore, the aim of the present study was to investigate whether MBF can be improved by the replacement of complete dentures for elderly people. Nine edentulous volunteers, average age 74·2 ± 5·5 years and average denture experience 19·4 ± 19·5 years (1–50 years), had replacement dentures made. Functional impressions were taken after border moulding using zinc oxide eugenol paste. After a rehearsal session, MBF was recorded with the old dentures, and with the new dentures immediately at insertion, at 3, 8 days, 2–3 weeks, 1, 2, 3 and 6–10 months post-insertion (p.i.). The MBF was recorded with the central bearing point method using a full-bridge strain gauge with a confirmed linearity from 1 to 1000 N and an accuracy of ±1 N. Data were analysed off-line using the mean of two peak readings per patient per session. The results indicate that MBF tended to be impaired when replacement dentures were first fitted (n.s.). However, this trend reversed during the first month p.i. for patients with a ‘moderate’ lower ridge resorption of Atwood (1963) grade 3 or 4 (n=5). Patients with more severe lower ridge resorption (Atwood grade 5 or 6; n=4) showed a significantly lower MBF over the entire observation period (P=0·05) and took longer to regain bite strength. Only patients with moderate bone resorption exceeded their pre-insertion level of MBF within the observation period of 6–10 months p.i. In contrast to one report of immediate improvement of MBF at insertion of a new or relined denture (Leyka et al., 2000), the present study suggests that, at least for elderly patients with severe bone resorption, delayed improvement of MBF should be expected.