ผลของลักษณะและความแข็งของยางวงแหวนที่มีต่อแรงในการยึดอยู่ / ปริยา คิดดี = Effect of different types and hardness of o-ring attachment on retentive force / Pariya Kiddee
This in vitro study was to determine suitable designs of O-ring for a ball attachment by using retentive and tensile forces and to consider correlation of these forces. The implant and O-ring block was prepared for retention testing. Osstem ball/O-ring system was used for comparison as a control and Fun Yim ball/ O-ring system was used as an experiment by varying O-ring designs (TR-Torus with inner round shape, CH-Cylindrical column with inner hexagonal shape, TH- Torus with Inner hexagonal shape, and CR-Cylindrical column with inner round shape) and materials (50, 60 and 70 shore A silicone). O-ring was aged by repeating up and down motion on the ball head for 1,440, 2,880 and 4,320 cycles. The retentive force of O-ring and tensile foece was measured using Universal Testing Machine with cross head speed at 120 mm/min (n=10). The data was analyzed statistically using Two-way ANOVA, Turkey (α=0.05) and Independent T-test. Result: The retentive forces decreased after accelerated aging except Fun Yim 70 CH and TH. The retentive forces of Fun Yim 70 CH and TH was higher than Osstem significantly. The tensile force of all group decreased after accelerated aging Conclusion: proper shape and hardness of sillicone affect the retentive force.
