J Adv Prosthodont.  2015 Aug;7(4):303-311. 10.4047/jap.2015.7.4.303.

Comparison of changes in retentive force of three stud attachments for implant overdentures

• Kim SM
• Choi JW
• Jeon YC
• Jeong CM
• Yun MJ
• Lee SH
• Huh JB

• KMID: 2118266
• DOI: http://doi.org/10.4047/jap.2015.7.4.303

Abstract

PURPOSE
The aim of this study was to compare the changes in retentive force of stud attachments for implant overdentures by in vitro 2-year-wear simulation.
MATERIALS AND METHODS
Three commercially available attachment systems were investigated: Kerator blue, O-ring red, and EZ lock. Two implant fixtures were embedded in parallel in each custom base mounting. Five pairs of each attachment system were tested. A universal testing machine was used to measure the retentive force during 2500 insertion and removal cycles. Surface changes on the components were evaluated by scanning electron microscopy (SEM). A Kruskal-Wallis test, followed by Pairwise comparison, was used to compare the retentive force between the groups, and to determine groups that were significantly different (alpha<.05).
RESULTS
A comparison of the initial retentive force revealed the highest value for Kerator, followed by the O-ring and EZ lock attachments. However, no significant difference was detected between Kerator and O-ring (P>.05). After 2500 insertion and removal cycles, the highest retention loss was recorded for O-ring, and no significant difference between Kerator and EZ lock (P>.05). Also, Kerator showed the highest retentive force, followed by EZ lock and O-ring, after 2500 cycles (P<.05). Based on SEM analysis, the polymeric components in O-ring and Kerator were observed to exhibit surface wear and deformation.
CONCLUSION
After 2500 insertion and removal cycles, all attachments exhibited significant loss in retention. Mechanism of retention loss can only be partially explained by surface changes.

Keyword

Overdenture attachment; Resilient attachment; Surface wear; Retention

MeSH Terms

Denture, Overlay*
Microscopy, Electron, Scanning
Polymers
Polymers

Figure

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  Fig. 1 Custom base mountings fabricated using acrylic resin. (A) Frontal view of the upper and lower mountings. (B) Bottom view of the upper mounting. (C) Top view of the lower mounting with implant fixtures.

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  Fig. 2 Attachment systems used in this study. From left to right: Kerator blue, O-ring red, and EZ lock.

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  Fig. 3 Base mounting with attachment systems. (A) Kerator blue, (B) O-ring red, (C) EZ lock.

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  Fig. 4 Graphical representation of retentive force during the 2500 insertion and removal cycles.

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  Fig. 5 Box-and-whisker plot of retention loss after 2500 insertion and removal cycles.

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  Fig. 6 Graphical representation of the percentage retentive force during 2500 insertion and removal cycles.

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  Fig. 7 Images of the matrices obtained by scanning electron microscopy (left: ×30, right: ×180 magnification) of the different attachment systems after 2500 cycles. (A, B) Kerator nylon matrix exhibiting wear changes, especially in the central core. (C, D) O-ring rubber matrix exhibiting deterioration and deformation. (E, F) EZ lock ceramic ball displaying a scratched surface. Boxes in (A, C, and E) correspond to (B, D, and F), respectively.

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  Fig. 8 Images of the patrices obtained by scanning electron microscopy (left: ×25, right: ×35 magnification) of the different attachment systems, after 2500 cycles. (A, B) Kerator titanium nitride-coated cylindrical patrix showed an absence of detectable wear. (C, D) O-ring uncoated titanium ball patrix exhibiting wear tracks (arrow). (E, F) The EZ lock titanium nitride-coated ball patrix also displayed absence of detectable wear.

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