The Effect of Mini Dental Implant Number on Mandibular Overdenture Retention and Attachment Wear

Abstract

Purpose. Evaluate the effect of different mini-implant numbers on overdenture retention and evaluate attachment wear following one year of simulated placement/removal. Material and Methods. Nine models simulating atrophic mandibles held 27 mini dental implants in three groups of 2, 3, and 4 mini-implants. A total of 1080 simulated placement/removal cycles were carried out, and a digital force gauge was used to measure the overdenture dislodgment force. The means of the retention forces were analyzed using SPSS with one-way ANOVA and post hoc ( $p<0.05$ ). The inner diameter of attachment inserts was evaluated using a light microscope before and after testing. A paired $t$ -test was used to compare the mean of inner ring diameters ( $p<0.05$ ). Results. The retention was significantly reduced regardless of the mini dental implant number, but the number affected overdenture retention. The placement of 4 mini dental implants provided higher retention and less reduction in retentiveness. However, no significant difference was found when 3 mini dental implants were compared to 2 mini dental implants ( $p=0.21$ ). Microscopic examination showed abrasion wear in all inserts following testing. However, the inserts of the 4 mini dental implants showed less wear than those used for 2 or 3 mini dental implants with $p\le 0.001$ and $p\le 0.001$ , respectively. Conclusion. Mini dental implant overdenture retention force and attachment wear could improve by increasing the mini dental implants to 4. However, there was no difference in retention force or attachment wear when 2 or 3 mini dental implant overdentures were compared.