[3D finite element analysis in consideration of the slide on residual ridge and the rigidity of mandibular complete denture].

PURPOSE

The motions and stress distributions of mandibular complete dentures during use were compared and investigated in terms of denture rigidity using 3D finite element method (FEM) stress analysis.

METHODS

Four models for analysis of mandibular complete dentures with different elastic modulus (1. A resin base denture (C), 2. A resin base denture with reinforcement wire (R), 3. A metal base denture (M), 4. A metal plate denture consisting of a double structure (T)) and measured using 3D FEM. Modes were separated into two elastic bodies: the dentures and residual ridge. Analyses were executed under the same conditions total loads of 20 kgf and contact.

RESULTS

1. The total equivalent-potential strain of dentures was high beneath the load point for C and R (2.38 approximately 2.86 x 10(-3)epsilon at buccal-shelf of working side and 0.55 approximately 0.68 x 10(-3)epsilon at posterior residual ridge). The entire dentures barely distorted for M and T (0.98 approximately 1.17 x 10(-3)epsilon at buccal-shelf of working side and 0.21 approximately 0.25 x 10(-3)epsilon at posterior residual ridge). 2. In the main stress distribution of mucosa beneath denture bases, high loads were located beneath the loading point of dentures, at lingual distal areas of the working side in C and R. In M and T, increasing the rigidity of dentures reduced the stress beneath the loading point of dentures. Stress was distributed widely and evenly.

CONCLUSIONS

When the rigidity of dentures is high, the strain of dentures decreases, the stress of the residual mucous membrane will evenly become distributed, and the distance of the balancing side from the denture border to the residual mucous membrane at the time of unilateral balanced position will decrease.