Effects of chemical surface treatments on the shear bond strength between polyetheretherketone and veneering composite resin: An in vitro study

AIM: To examine the effects of different chemical surface treatments on the shear bond strength (SBS) between milled PEEK and veneering composite resin. SETTINGS AND DESIGN: This was an in vitro comparative study. MATERIALS AND METHODS: Sixty PEEK discs were assigned to four groups ( n = 15): no surface treatment (PEEK), bonding using a methyl methacrylate (MMA)-based adhesive (Single Bond Universal) (PEEK + BD), 10% hydrofluoric acid etching followed by bonding (PEEK + HFA + BD), and 98% sulfuric acid etching followed by bonding (PEEK + H 2 SO 4 + BD). The specimens were all bonded by using a MMA-based adhesive (Single Bond Universal). A luting agent (RelyX U200) was used to bond the composite resin (Universal Filtek Z350 X T) to the pretreated PEEK surfaces. An Instron universal machine was used to calculate the SBS between the PEEK and the composite resin following ISO 10477. Failure modes (cohesive, adhesive, and mixed) and interface morphology were analyzed by stereomicroscopy. Data were analyzed using the one-way ANOVA and Tukey's post hoc tests ( a = 0.05). STATISTICAL ANALYSIS USED: Data were analyzed using the one-way ANOVA and Tukey's post hoc tests ( a = 0.05). RESULTS: The mean SBS values of the PEEK + H 2 SO 4 + BD group (2.09 ± 0.90 MPa) were significantly higher than those of all other groups ( P < 0.05). The 10% HFA etching did not significantly affect the SBS values compared to the control group ( P > 0.05). PEEK + H 2 SO 2 +BD group also had the largest number of cohesive (55%) and mixed (45%) failures. CONCLUSION: Etching with 98% sulfuric acid followed by a bonding agent significantly improved SBS between milled PEEK and veneer composite, although yet below the minimal threshold values.