The effect of surface treatment on the bonding properties of Polyetherketoneketone (PEKK) polymer to veneering materials: a systematic review and meta-analysis

BACKGROUND: This systematic review and meta-analysis aim to compile and critically evaluate the existing published literature evaluating the effect of surface treatment on the bonding properties of the Polyetherketoneketone (PEKK) polymer to veneering materials. METHODS: The PICO (Participant, Intervention, Comparison, Outcome) question ordered for the review was: What influence do surface pretreatments have on the bond strength between PEKK resin and veneering materials? The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines served as the basis for structuring and reporting this systematic review and meta-analysis. Two independent researchers systematically searched four electronic databases (PubMed, Scopus, Web of Science, and Cochrane) to identify all articles published up to 15th December 2025. To meet the individual requirements of each electronic database, minor alterations in the search strings were made. RESULTS: Initial search yielded 242 hits. After removing duplicate and irrelevant titles, the complete texts of the leftover articles were assessed, and 15 articles were ultimately selected that met the inclusion criteria. Quality analysis was performed using the Modified CONSORT scale, which indicated a high to medium level of study quality. When the GRADE approach was used to rate the quality of the evidence, it was revealed that the studies have moderate certainty. Eleven out of fifteen articles were included in the meta-analysis. For composite resin, air abrasion with alumina significantly increased shear bond strength (SBS) with a pooled standardized mean difference (SMD) of 4.79 (95% CI: 2.24, 7.34), and sulfuric acid etching showed a pooled SMD of 2.92 (95% CI: 0.40, 5.44). For lithium disilicate ceramic, air abrasion with alumina yielded an SMD of 2.70 (95% CI: 1.16, 4.24), and sulfuric acid etching an SMD of 1.75 (95% CI: 0.22, 3.27). Tribochemical silica coating also showed significant improvements. Non-thermal air plasma's effect on composite resin was not statistically significant (SMD: 0.51, 95% CI: -2.15, 3.18). CONCLUSION: Within the study's limitations, it can be concluded that surface pretreatment of the PEKK polymeric material is an essential step before bonding the veneering material. In vitro evidence suggests that surface pretreatments like air abrasion with 100-110 μm alumina or acid etching with 90-95% sulfuric acid demonstrate promising results for improving bond strength.