Comparative Stress Distribution of Implant-Retained Mandibular Ball-Supported and Bar-Supported Overlay Dentures: A Finite Element Analysis
Implant-retained mandibular ball-supported and bar-supported overlay dentures are the two most common treatment options for the edentulous mandible. The superior option in terms of strain distribution should be determined. The three-dimensional model of mandible (based on computerized tomography scan) and its overlying implant-retained bar-supported and ball-supported overlay dentures were simulated using SolidWorks, NURBS, and ANSYS Workbench. Loads A (60 N) and B (60 N) were exerted, respectively, in protrusive and laterotrusive motions, on second molar mesial, first molar mesial, and first premolar. The strain distribution patterns were assessed on (1) implant tissue, (2) first implant-bone, and (3) second implant-bone interfaces. Protrusive: Strain was mostly detected in the apical of the fixtures and least in the cervical when bar design was used. On the nonworking side, however, strain was higher in the cervical and lower in the apical compared with the working side implant. Laterotrusive: The strain values were closely similar in the two designs. It seems that both designs are acceptable in terms of stress distribution, although a superior pattern is associated with the application of bar design in protrusive motion.Abstract

Figure 1. The tissue effect of the loads in laterotrusive (a) and protrusive (b) motions with the application of ball-supported overlay dentures. Figure 2. The bony effect of the loads on the working side in the laterotrusive motion of the ball-supported (a and b) and bar-supported (c and d) overlay dentures.

The bony effect of the loads on the nonworking side in the laterotrusive motion of the ball-supported (a and b) and bar-supported (c and d) overlay dentures.

The bony effect of the loads on the working side in the protrusive motion of the ball-supported (a and b) and bar-supported (c and d) overlay dentures.

Figure 5. The bony effect of the loads on the nonworking side in the protrusive motion of the ball-supported (a and b) and bar-supported (c and d) overlay dentures. Figure 6. The tissue effect of the loads in laterotrusive (a) and protrusive (b) motions with the application of bar-supported overlay dentures.
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