Effect of laser etching on shear bond strength between polyether ether ketone (PEEK) and maxillofacial silicone after...

Debonding of silicone prostheses from metal substructures is a frequently reported complication in prosthodontics. Polyether ether ketone (PEEK) has emerged as a promising alternative framework material owing to its favourable biomechanical properties; however, its limited bond strength to silicone remains a concern. The present study aimed to evaluate the shear bond strength between PEEK and maxillofacial silicone following laser etching of PEEK and subsequent accelerated ageing.

According to ISO 10477:2020, 128 PEEK specimens were fabricated using Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) with 10 mm diameter and 3 mm thickness, and silicone specimens with 5 mm diameter and 2.5 mm height. The specimens were categorised into: Group 1-no surface treatment, Group 2-Al₂O₃ air abrasion, Group 3-98% sulphuric acid etching, and Group 4-laser irradiation. The silicone specimens were bonded to PEEK and kept at room temperature for 24 h for polymerisation, and were subjected to accelerated ageing for 252, 504, and 1,008 h. The shear bond strength was evaluated using universal testing machine at 1 mm/min crosshead speed. The comparison within groups was done using one-way analysis of variance (ANOVA) and multiple group comparison was done using Tukey's HSD (Honestly Significant Difference) post-hoc analysis.

Statistical analysis showed that surface pretreatment had a significant effect on bond strength (p < 0.05). Laser treatment and air abrasion produced significantly higher bond strengths compared to sulfuric acid etching, while no significant difference was found between laser treatment and air abrasion. Accelerated ageing time also had a significant influence, with bond strength values decreasing progressively from 252 h to 1,008 h across all pretreatment groups.

Surface pretreatment significantly influenced the adhesion of maxillofacial silicone to PEEK. Laser treatment and air abrasion provided superior and statistically comparable bond strengths, whereas sulfuric acid etching was less effective. Accelerated ageing reduced bond strength over time, highlighting the effect of ageing conditions on the durability of adhesion.