title: The effect of variation of the lingual shape of mandibular complete dentures on lingual resistance to lifting forces.
abstract: 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.
  
  
  METHODS
  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.
  
  
  METHODS
  A clinical research laboratory.
  
  
  METHODS
  Five experienced complete denture wearers between age 64 and 82 years.
  
  
  METHODS
  Lifting forces were applied at the midline, left and right premolar sites in random order.
  
  
  METHODS
  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.
authors.affiliation: St Bartholomew's and the Royal London School of Medicine and Dentistry, London, England. bill.miller@stonebow.otago.ac.nz
authors.forename: W P
authors.initials: WP
authors.lastname: Miller
authors.forename: B
authors.initials: B
authors.lastname: Monteith
authors.forename: M R
authors.initials: MR
authors.lastname: Heath
mesh_terms: D000222:Adaptation, Physiological; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D016321:Dental Care for Aged; D003799:Dental Stress Analysis; D003779:Denture Design; D003781:Denture Retention; D003826:Denture, Complete, Lower; D006801:Humans; D008875:Middle Aged; D011312:Pressure; D014059:Tongue / Q000502:physiology