The effect of number and distribution of maxillary implants on the load on the palate under implant-retained overdentures

Abstract

Purpose: to evaluate the effect of the number and distribution of dental implants on the occlusal pressure transmitted to the palate. Material and Methods: eight implant analogs were placed in a replica of maxilla in the areas of teeth number 3, 4, 5, 6, 11, 12, 13 and 14. Locator attachments were attached to the implant analogs. The distances between the centers of implant analogs on each side were 8 mm. Fifteen denture bases with occlusal rims were fabricated to fit on the maxillary replica. Under a load of 245 N, pressure on the palate was measured under each denture base in six different designs of Locator insertions: No Locators, 2 Locators, 4 Locators with distances of 8, 16, and 24 mm and 8 Locators. Data was analyzed using One-Way ANOVA and Tukey's HSD test. A p value of ≤0.05 was considered significant. Results: Pressure transmitted to the palate ranged from 20.67 +/- 16.06 N (mean +/- SD) for overdentures supported by 8 Locators to 85.61 +/- 27.94 N for a conventional denture (control). The amount of pressure transmitted to the palate when the overdentures were supported by 4 Locator attachments, was significantly lower than when no, or when two Locator attachments were used. However, they were not significantly different from each other. When the overdentures were supported by 8 locator attachments, the pressure transmitted to the palate was significantly lower than that of conventional dentures, overdentures supported by 2 Locator attachments and overdentures supported by 4 Locator attachments when the distance between the anterior and posterior implants was 8 mm. Conclusion: Using 4 Locator attachments produced significantly less pressure on the palate, compared to when zero or two Locators were used. When the distance between the 4 Locators was 16 or more mm, the pressure was not significantly lower than 8 Locator design, suggesting that the palate of a 4 implant-retained overdenture with a distance of 16 mm or more, does not contribute significantly to the pressure distribution under the overdenture. Considering the static nature of the load, the results of this study should be interpreted clinically with caution.