Abstract
Statements of the problem
Over the past decades, conventional complete dentures were used for various patients although they have incomplete function. Overdentures using dental implants could help the improvement of denture function.
Purpose
The purpose of this study was to compare the strains of abutment and bone on implant overdenture between splinted and unsplinted type of prosthesis. Additionally, the strain values of parallel placed implant model and unparallel placed implant model were compared.
Material and methods
Two acrylic resin model were prepared and two implants were placed at the canine positions in each model. In the first model, two implant were placed parallel. In the second model, two implants were placed with 10 degree labiolingual divergence. Two types of abutment were connected to the fixtures alternatively. One was splint type of Hader bar, the other was unsplint type of ball abutment. Overdentures were fabricated with corresponding attachment systems and seated on abutments. Strains of abutments and labial bone simulants were measured with electric resistance strain gauges when static load from 100 N to 200 N were applied to overdentures.
Results
1. Splinted type of overdentures using bar and clip showed higher absolute strain values. But the strain was compressive and the load was shared by two implants (P < .05). 2. Unsplinted type overdentures using ball and O-ring showed low absolute strain values (P < .05). 3. Labially inclined implant showed higher tensile strain values in unsplinted type of prosthesis than in splinted type of prosthesis. Lingually inclined implant showed rather low strain values under load (P < .05). 4. Non parallel implant model showed higher absolute strain values than parallel placed implant model comprehensively (P < .05).
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Fig. 1.
Strain gauges (Curiosity Technology, Seoul, Korea) bonded to cast bar and labial bone simulant.
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Table I.
Strain values on bar type overdenture in parallel placed implant model
Table II.
Strain values on unsplint type overdenture in parallel placed implant model
Table IV.
Strain values on unsplint type overdenture in unparallel placed model
Table III.
Strain values on bar overdenture in unparallel placed implant model