Principles of Attachment Selection for Implant Supported Overdentures
| Principles of Attachment Selection for Implant Supported Overdentures | Hamid Shafie, DDS* and George Obeid, DDS** |
Volume 19.6 Download
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Due to these design features, the Locator® rapidly became one of the most popular stud attachments and, as of 2010, was available for approximately 350 different implants from 70 manufacturers.
Self Alignment The majority of overdenture attachments can become distorted upon insertion if the patient does not carefully align the male and female elements of their appliance along a set path-of-insertion. Many patients have a tendency to “bite” their overdenture into place at an angle, causing damage and requiring replacement. To address this issue, the Locator® attachment was designed to be self-aligning. The rounded occlusal contours of the female element work in conjunction with the skirt of the nylon male to guide the attachment into place in a way similar to the guide planes of partial dentures. (Fig.2A) Dual Retention To maximize retentive capability and longevity, the Locator® was designed with |
dual retention. The nylon male element engages the inside and the outside contours of the female abutment. (Fig. 2B) This feature doubles the surface area for retentive contact. Cyclic durability and longevity tests have shown that the standard nylon males maintain significant retention for more than 110,000 cycles.27 The standard nylon color-coded males provide from 1.5 to 5 lbs of retention. (Fig. 2C) Gray zero-retention inserts are also available to reduce retention when desired. (Fig. 2D)
Pivoting Feature Another well-known challenge with overdenture attachments is divergence. Divergence between implants is an all too common cause of excessive wear and may prevent the appliance from seating completely. The Locator® male insert was uniquely designed to pivot within the metal housing upon insertion, removal and mastication. This ability to pivot allows the standard male to accommodate 10° each, for a total of 20° between implants. (Fig. 2E) To allow for greater divergence between implants, Extended Range males were designed without the center nipple. Tests have shown that this concept allows for a
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