The influence of uneven placement of mini dental implants on retention form of lower complete over denture: An in vitro study

Abstract

Objectives: This in vitro study aimed to evaluate the effect of placing two mini-dental implant (MDI) at different heights on the retention form of the lower over denture (OD). Materials and Methods: Sixteen acrylic mandibular blocks and their corresponding ODs were prepared and divided into four groups (four sets per group) to represent an atrophic mandibular ridge with two MDIs placed parallel to each other at inter-implant heights (IHs) of 0.0, 1.5, 3.0, and 4.5 mm. The OD blocks were mounted on a manual pulling stand and pulled vertically 12 times to measure the peak tension load (N). The data were analyzed using one-way analysis of variance (ANOVA), and the differences between the means were compared (P < 0.05). Results: One-way ANOVA showed a statistically significant effect of IH on the retention force of the OD blocks (P < 0.05). The mean retention force (N) for evenly placed MDIs was as follows: 32.2 ± 0.95, 1.5 mm IH: 30.1 ± 0.56, 3.0 mm IH: 26.1 ± 0.71, and 4.5 mm IH: 27.4 ± 0.90. Conclusion: The retention force of the OD blocks was significantly affected by the vertical inter-implant distance. A significant reduction in the mean retention force was observed for ODs retained by MDIs placed at an IH >1.5 mm.