The effect of clip material on the retention of implant retained mandibular overdenture: randomized clinical study

A Better Grip for Lower Dentures

Many people who have lost all their lower teeth struggle with dentures that slip, wobble, or make eating difficult. One popular solution is to secure the denture onto dental implants with a small bar and tiny clips, giving the denture a much firmer hold. This study asks a practical question that matters to both patients and dentists: when that bar is made from a modern plastic called PEEK, do traditional nylon clips work any better or worse than clips made from the same high-tech plastic?

Why Lower Dentures Often Feel Unstable

The lower jaw is a challenging place for full dentures. Bone can shrink over time, the tongue and cheeks are constantly moving, and there is less surface area for a denture to rest on. Even well-made dentures may feel loose. To improve this, dentists often place two implants in the front part of the lower jaw and connect them with a bar. The denture then “snaps” onto this bar using small clips, which greatly improves grip and chewing ability. However, these clips are made from different materials, and they gradually wear out as patients remove and replace their dentures every day.

A New Plastic in the Dentist’s Toolkit

PEEK is a strong, lightweight, tooth-colored plastic originally developed for industry and now used in medicine and dentistry. It resists chemicals, does not easily attract plaque, and is considered biologically safe. In bar-and-clip denture systems, the bar can be made of metal or PEEK, and the clips can be made from metal or various plastics such as nylon or PEEK. Because clips are the parts that wear and may need replacement, dentists want to know which material holds well over time without needing frequent maintenance or driving up costs.

How the Study Was Carried Out

In this clinical study, twenty men who had no teeth in their lower jaw received two implants placed near the canine–premolar area. After healing, each patient received a custom-milled PEEK bar screwed onto the implants. All patients were given lower overdentures that snapped onto this bar, but they were randomly divided into two groups: one group had ready-made nylon clips, and the other had custom-made PEEK clips. The researchers measured how strongly the dentures were held in place right after insertion, and again after three months, six months, and one year. To do this, they used a testing machine that gently pulled on the denture until it released, recording the force needed to dislodge it.

What the Results Showed Over a Year

Across the full year, both types of clips showed very similar holding strength. At each time point—immediately after fitting, at three months, six months, and twelve months—the average forces needed to pull off the dentures were almost the same for nylon and PEEK clips. The overall grip changed over time: it tended to rise slightly at three and six months and then drop somewhat by one year, reflecting natural wear and changes in how the denture fits and is used. However, the material of the clip itself did not create a meaningful difference in how firmly the denture stayed in place on the PEEK bar.

What This Means for Patients and Dentists

For patients wearing implant-supported lower dentures on a PEEK bar, this study suggests that both nylon and PEEK clips can provide similarly secure retention for at least one year. In everyday terms, choosing between these two clip materials is unlikely to make a noticeable difference in how firmly the denture stays put, at least in the short to medium term. Because PEEK clips tend to be more expensive, their higher cost may not be justified purely on the basis of holding strength. Future research with more patients and longer follow-up will help clarify whether one material lasts longer or feels better, but for now, both options appear to offer a reliable grip.

Citation: Mohamed, S.M., Sayed, A.M. The effect of clip material on the retention of implant retained mandibular overdenture: randomized clinical study. BDJ Open 12, 32 (2026). https://doi.org/10.1038/s41405-026-00419-y

Keywords: implant overdenture, PEEK bar, nylon clip, denture retention, mandibular implants