# Evaluation of adhesion strength of pure PEEK and glass reinforced PEEK with titanium using different bonding methods- a systematic review

## TL;DR

This paper reviews methods to improve adhesion between PEEK and titanium for biomedical implants, finding laser structuring and air-particle abrasion most effective.

## Contribution

The study systematically compares bonding methods for PEEK and titanium, highlighting laser structuring's 300% adhesion strength improvement.

## Key findings

- Laser structuring increased adhesion strength by up to 300% compared to untreated surfaces.
- Air-particle abrasion improved shear bond strength by 0.4 MPa, especially with bonding agents.
- Glass-reinforced PEEK showed better adhesion than pure PEEK when combined with acid etching or plasma spraying.

## Abstract

Due to their versatility, mechanical strength, and biocompatibility, polyetheretherketone (PEEK) and its composite form have attracted a lot of attention for biomedical applications. However, creating long-lasting adhesion between PEEK and titanium remains a significant difficulty, particularly for implants and prostheses. Although surface treatments and bonding techniques have been studied for better interfacial adhesion, it is unclear how effective they are in comparison.

Using various surface preparation and bonding processes, a systematic study was conducted to evaluate the adhesion strength of glass-reinforced PEEK bonded with titanium and pure PEEK. Surface preparation methods, bonding agents, adhesion strength (MPa), and failure mechanisms were investigated using a combination of experimental and in vitro investigations. The effectiveness of certain treatments, such as laser structuring, air-particle abrasion, and chemical alterations, was compared statistically.

In contrast to air-particle abrasion, which produced shear bond strength gains of 0.4 MPa and significantly higher values when combined with bonding agents, laser structuring improved adhesion strength by up to 300% over untreated surfaces, according to the 10 studies that made up the review. The adhesion properties of glass-fiber-reinforced PEEK were superior to those of clean PEEK, particularly when combined with acid etching or plasma spraying. Microscopic investigations revealed improved mechanical interlocking and interfacial contacts, with adhesive and mixed failure modes predominating. Better durability was shown by thermocycling techniques; samples that were cycled 5000–1,200,000 times demonstrated increased adhesive strength in simulated environments.

This study demonstrated that surface treatment techniques, particularly air-particle abrasion and laser structuring, significantly increased the adhesion strength between titanium and PEEK and glass-reinforced PEEK. Potential treatment approaches were suggested since high-performance bonding agents also promoted long-term interfacial adhesion. However, standardisation is necessary to improve comparability due to variations in methodology among research.

The online version contains supplementary material available at 10.1186/s12903-025-07323-1.