Photelastic stress analysis is useful in dentistry for evaluating stress distribution. So, three dimensional photoelasticity was used in this study.
The purpose of this study was to investigate the stress distribution when complete dentures supported by shape memory implants occluded in centric, lateral and protrusive relationships.
In this study, shape memory implants whose shape could be changed by thermal change after insertion were embedded mandibular photoelastic epoxy resin models.
Constructed complete dentures were mounted on the whip-mix articulators to maintain centric position. Mounted dentures were loaded in a pure vertical difestion with 0.7㎏ on the center of upper jaw member of articulator in each case. Stresses were frozen into epoxy edentulous models at 130℃ in the stress freezing furnace.
The stress-frozen epoxy models were sliced with high speed steel into 6 mm thickness.
The slices were examined with a circular polariscope.
The results were as follows.
1. In centric relation of conventional dentures, the stresses were the highest value at the cuspid area, and anterior region showed higher stresses than the posterior region.
2. In centric relation of dentures supported by shape memory implant, all the region except anterior portion showed high stress.
3. In lateral functional postition, working side showed higher stresses than the balancing side.
4. In protrusive position, stress distribution was almost symmetrical and the stresses were concentrated at the cuspid region.
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