# Ball versus other attachments in mini implant retained overdenture: a systematic review and meta-analysis

## TL;DR

This study compares different attachment systems in mini implant overdentures and finds similar bone loss outcomes for ball, bar, and ERA® attachments, with telescopic attachments showing more bone loss.

## Contribution

The study provides a systematic review and meta-analysis comparing ball attachments with other systems in mini-implant overdentures.

## Key findings

- Ball attachments showed better results than telescopic ones in marginal bone loss (p < 0.05).
- Ball, bar, and ERA® attachments had similar marginal bone loss outcomes.
- Ball attachments required fewer interventions than ERA® attachments over one year.

## Abstract

Mini implant retained overdentures have been treated in edentulous patients with promising long-term results. However, various attachment systems in this process remain insufficiently investigated. This systematic review and meta-analysis aimed to compare the effects of the ball and other attachments used in mini-implant overdentures. Marginal bone loss, bite force, implant survival rate, prosthetic maintenance, and complications were assessed.

A systematic search was conducted across PubMed, Cochrane Library, and Scopus databases until 25th February 2025. This systematic review aimed to find studies that compare ball attachments with other attachment systems in mini dental implant (MDI) overdentures. The primary outcome was marginal bone loss, while the secondary outcomes were maximum bite force, implant survival rate, prosthetic maintenance, and complications. The risk of bias was assessed using the Cochrane risk-of-bias tool for RCTs, and a quantitative meta-analysis was performed.

Of the 561 publications, six randomized clinical trials (101 participants, 234 mini-implants) met the inclusion criteria. Risk of bias assessment revealed three studies with a low risk of bias and three studies with some concerns for risk of bias. There was no significant difference in the marginal bone loss between the ball attachments and others (WMD = 0.15, 95% CI -0.50 to 0.81, p = 0.65), though ball attachments performed better than telescopic ones (P < 0.05) in subgroup analysis. No significant difference in bite force was found (WMD = -5.29, 95% CI -33.46 to 22.87, p = 0.71). Two-year survival rates were 90.9% for ball and 97.8% for bar attachments. The ERA® (Extra-Coronal Resilient Attachment) group required five interventions (sore spot adjustments, relining, nylon replacements), while the ball attachment group required only two (denture repair, nylon cap replacement) over the one-year follow-up period.

Within the limitations of the study, it can be concluded that ball, bar, and ERA® attachments yield similar outcomes in marginal bone loss while telescopic attachments show more statistically significant marginal bone loss (p < 0.05). The type of attachment does not significantly affect maximum bite force.

CRD42024610018.