Oral Health and Dental Management

Abstract

Effect of One Piece versus Two Piece Mini Implants on Bone Height of Implant Retained Mandibular Overdenture

Ahmed El Damarisy, Amr Mohamed Ismail Badr, Fardos Nabil Rizk, Jehan Fekry Mohamed

Severely atrophied mandibles are a common problem within elderly completely edentulous patients. Given their small diameters, long height and self-tapping characteristics, mini-implant retained over-dentures are a valuable treatment option in such patients. Mini-implants are usually once-piece implants, however recently two-piece mini-implants were introduced with aim of addressing angulation problems. The success of the latter has not been thoroughly studied. Crestal bone height measurements are normally used to evaluate implant success. Therefore, this study was conducted to evaluate the effect of one piece versus zero degree two piece ERA mini implants on crestal bone height of implant retained mandibular over-denture. Twelve male, completely edentulous patients ranging between sixty to seventy years old were randomly divided into two groups. Group A: patients were rehabilitated with four one-piece ERA mini-implant retained mandibular over-dentures and upper complete dentures. Group B: patients were rehabilitated with four two-piece ERA mini-implant retained mandibular over-dentures and upper complete dentures. Immediate loading was performed and crestal bone height measurements were conducted using Cone Beam Computed Tomography during loading, six and twelve months following denture insertion. No clinical and radiographic signs of implant failure were observed in both groups. Both groups showed a significant decrease in peri-implant bone height (within the acceptable range; less than one and a half millimeter within first year). The amount of bone loss between both groups during the follow up period was not significant. Due to the insignificant difference in bone loss, the choice between one and two-piece mini-implants narrows down to the surgical protocol. In case guided implant surgery (that eliminate angulation problems) are to be performed, given the simpler procedure onepiece mini-implants might be the treatment of choice. However, when guided surgery is not a viable option, two-piece miniimplants are preferred.