IADR Abstract Archives
Clasp Deformation: CoCr and Ultaire™ AKP Clasps Following Cyclical Loading
Objectives: There is little information quantifying the permanent deformation of CoCr and polymeric denture clasps following in vitro fatigue testing. Only 2-dimensional measurements of changes in clasp tip-to-tip distance have been reported; these may not represent the true 3-dimensional situation. There are no reports investigating the magnitude of deformation in the individual active and reciprocating arms. Objective: To quantify tip-to-tip deformation in 3-dimensions and to apportion the relative contributions of the active and reciprocating arms to the overall deformation.
Methods: 12 CoCr and 12 Ultaire™ AKP (Solvay Dental 360™) clasps were constructed and inserted/removed from eMax crowns 15,000 times (1.1Hz) using a dynamic testing machine (ElectroPulsTM 3000, Instron) in artificial saliva at 37°.
Prior to mechanical testing, all clasps were scanned in a 3D model scanner (DS2 Solutionix).
The clasps were then scanned again following mechanical testing, and each aligned to its pre-test facsimile using the rest seat region as a reference in MeshLab (www.meshlab.net). The 3-dimensional maximum positive deformation of each pair of clasp tips – pre-test active to post-test active and pre-test reciprocal to post-test reciprocal – were measured. Significance was tested using 1-way ANOVA with post-hoc Bonferroni correction.
To test reproducibility of the method, a single clasp was scanned five times following fatigue testing and the deformation results were analyzed as before.
Results: The method reproducibility was 0.06 ± 0.02mm (active clasp) and 0.04 ± 0.02mm (reciprocal clasp). The mean CoCr active clasp tip deformation was 0.21 ± 0.10mm. The mean Ultaire™ AKP active clasp tip deformation was 0.06 ± 0.07mm. The mean CoCr reciprocating clasp tip deformation was 0.12 ± 0.13mm. The mean Ultaire™ AKP reciprocating clasp tip deformation was 0.03 ± 0.03mm. Deformation in CoCr active clasp tips was significantly larger than Ultaire™ AKP deformation in active clasp tips (p<0.001).
Conclusions: We have presented a novel method for measuring 3-dimensional clasp tip deformation for denture clasps.
Ultaire™ AKP clasps showed significantly less deformation than CoCr in the active clasp tip following 15,000 simulated insertion/removal cycles.
Methods: 12 CoCr and 12 Ultaire™ AKP (Solvay Dental 360™) clasps were constructed and inserted/removed from eMax crowns 15,000 times (1.1Hz) using a dynamic testing machine (ElectroPulsTM 3000, Instron) in artificial saliva at 37°.
Prior to mechanical testing, all clasps were scanned in a 3D model scanner (DS2 Solutionix).
The clasps were then scanned again following mechanical testing, and each aligned to its pre-test facsimile using the rest seat region as a reference in MeshLab (www.meshlab.net). The 3-dimensional maximum positive deformation of each pair of clasp tips – pre-test active to post-test active and pre-test reciprocal to post-test reciprocal – were measured. Significance was tested using 1-way ANOVA with post-hoc Bonferroni correction.
To test reproducibility of the method, a single clasp was scanned five times following fatigue testing and the deformation results were analyzed as before.
Results: The method reproducibility was 0.06 ± 0.02mm (active clasp) and 0.04 ± 0.02mm (reciprocal clasp). The mean CoCr active clasp tip deformation was 0.21 ± 0.10mm. The mean Ultaire™ AKP active clasp tip deformation was 0.06 ± 0.07mm. The mean CoCr reciprocating clasp tip deformation was 0.12 ± 0.13mm. The mean Ultaire™ AKP reciprocating clasp tip deformation was 0.03 ± 0.03mm. Deformation in CoCr active clasp tips was significantly larger than Ultaire™ AKP deformation in active clasp tips (p<0.001).
Conclusions: We have presented a novel method for measuring 3-dimensional clasp tip deformation for denture clasps.
Ultaire™ AKP clasps showed significantly less deformation than CoCr in the active clasp tip following 15,000 simulated insertion/removal cycles.