# Milled in versus round bar for mini implant retained mandibular overdentures: a 8-year retrospective radiographic study of peri-implant bone changes and posterior ridge resorption

## TL;DR

This study compared two types of bars used with mini implants for lower dentures and found differences in bone loss and ridge resorption over 8 years.

## Contribution

The study provides long-term radiographic data on the performance of milled versus round bars with mini implants for mandibular overdentures.

## Key findings

- Group I (milled bars) showed higher marginal bone loss compared to Group II (round bars).
- Posterior ridge resorption was significantly higher in Group II at certain intervals.
- Anchorage system design significantly affects long-term bone changes around mini implants.

## Abstract

This retrospective radiography study’s main objective was to compare round and milled bars for mandibular overdentures assisted by 4 mini-dental implants (MDI) on peri-implant marginal bone loss (MBL)and posterior mandibular ridge resorption(PRR) after 8 years.

Thirty male Participants in a retrospective analysis were treated between 2016 and 2024 who had four interforaminal mini implants supporting an overdenture on a milled bar. Two equal groups of 15 patients each were randomly assigned to receive mandibular overdentures: Group I received overdentures retained by milled bars, while Group II received overdentures retained by round joint bars. After an 8-year follow-up period, a comparison between the two bar designs attachment used for IODs retention. The evaluation of the posterior ridge resorption (PRR) and peri-implant marginal bone loss(MBL) was done after three years (T3), five years(T5), and eight years later (T8)after insertion. The data was analyzed using the Statistical Package of Social Science (SPSS) program for Windows (Standard version 24).

Compared to Group II, Group I’s MBL was noticeably higher. As time went on, MBL rose noticeably for both groups. At certain intervals, Group II’s PRR was significantly higher than its Group I.

The design of the anchorage system has a major impact on posterior ridge resorption and peri-implant bone loss when four mini-implants are utilized to anchor mandibular overdentures.

As mini implants are often seen as a cost-effective solution for patients with limited bone, it is important to understand their long-term performance to make more informed decisions in clinical practice.

(NCT06185283). Retrospectively registered on (29-12-2023).