| Sumario: | Coated titanium denture attachments have been studied to ensure adequate retention. However, studies on the retentive force of zirconia denture attachment under different implant angulations and insertion-removal cycles are lacking. The purpose of this in vitro study was to evaluate the effect of different implant angulations and insertion-removal cycles on the retentive force of coated titanium and zirconia denture attachments. Nine patrix blocks and 9 matrix blocks were equally divided into 3 denture attachment groups: 2 coated titanium attachments (LOCATOR and LOCATOR R-Tx) and 1 zirconia attachment (Zeramex Docklocs patrix). Each attachment group was subdivided into 3 subgroups based on implant angulation (0-, 15-, and 30-degrees) (n=8). Each specimen underwent up to 3240 cycles of denture insertion-removal. Retentive force was measured 5 times and averaged at insertion-removal cycles of 0, 270, 540, 810, 1080, 2160, and 3240. Data were analyzed by using 3-way repeated measures ANOVA (α=.05). Significant interactions were observed among denture attachment, implant angulation, and insertion-removal cycle (P <.001). In the 0-degree group, retentive forces among all attachments demonstrated no significant differences (P >.999), while, in the 15- and 30-degree groups, retentive forces among all attachments demonstrated significant differences (P <.001). Comparing implant angulations, the retentive force in the LOCATOR R-Tx group exhibited no significant differences (P >.999), while the retentive force in the LOCATOR and Zeramex Docklocs groups exhibited significant differences (P <.001). The retentive force in each attachment group tended to decrease as insertion-removal cycles increased (P <.001). The Zeramex Docklocs zirconia denture attachment provided retention similar to that of the coated titanium attachments at 0-degree implant angulation; however, at 15- and 30-degree implant angulations, the LOCATOR attachment provided the greatest retention, followed by Zeramex Docklocs and LOCATOR R-Tx. Implant angulation up to 30 degrees affected the retention of the LOCATOR and Zeramex Docklocs attachments, while it did not impact the retention of the LOCATOR R-Tx attachment. Retention decreased over time in both zirconia and coated titanium attachments.
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