The effect of variation of the lingual shape of mandibular complete dentures on lingual resistance to lifting forces.

UNLABELLED

Increasing life expectancy, age related reduction in adaptability and progressive severe mandibular resorption all add to the importance of any factor improving the prosthetic success.

OBJECTIVE

To investigate the effect of two different lingual shapes of lower dentures on patients' ability to resist lifting forces.

DESIGN

Tongue pressures on the lingual surface of complete mandibular experimental dentures were recorded from mid-line, premolar and molar transducers. Two experimental prostheses were fabricated for each subject: one conventionally contoured, the other formed by piezography.

SETTING

A clinical research laboratory.

SUBJECTS

Five experienced complete denture wearers between age 64 and 82 years.

INTERVENTION

Lifting forces were applied at the midline, left and right premolar sites in random order.

MAIN OUTCOME MEASURES

Peak resistance to lifting forces and lingual pressures used during these tests.

RESULTS

Lingual pressures exerted anteriorly were dramatically higher than those on premolar and molar surfaces. Significantly higher pressures were used to resist lifting forces applied to piezographically than conventionally formed contours; correspondingly, significantly higher lifting peak forces were, on average, resisted.

CONCLUSIONS

Providing a lower denture with a piezographically produced lingual surface was shown, in this preliminary study, to enhance tongue retentive ability over a conventional design. It seems reasonable to maximise retentive potential with oblique sublingual polished surfaces and minimise the adaptive demand, particularly for older patients, by using a piezographic technique which "customises" the contour and precludes over-extension.