Fracture strength and failure mode of implant-supported provisional resin composite crowns on hydroxyapatite-coated sulfonated PEEK abutments following thermomechanical loading.

PURPOSE: This study evaluates the fracture strength and failure mode of implant-supported provisional resin composite crowns fabricated over hydroxyapatite-coated sulfonated polyetheretherketone (PEEK) and sandblasted PEEK abutments after thermomechanical loading. MATERIALS AND METHODS: Thirty customized PEEK provisional abutments were surface-treated by (1) sandblasting with 50 µm aluminum oxide (n = 15) (Sa) and (2) HA coating after sulfonation (n = 15) (HA). These abutments were veneered to create crowns for the mandibular right first permanent molar using bulk-fill resin composites after applying a thin layer of universal adhesive. All specimens were stored in distilled water at 37℃ for 24 hours, underwent thermocycling for 1000 cycles at 5℃ and 55℃ (30 s dwell time and 10 s transfer time), and were subjected to mechanical cyclic loading for 120,000 cycles with 50 N using a chewing simulator at room temperature. Fracture strength was evaluated with a universal testing machine, and failure mode was analyzed using a 3D surface profilometer. The Mann-Whitney U test was used for statistical analysis (α = 0.05). RESULTS: The HA group exhibited significantly higher fracture strength (1469.71 N ± 200.36 N) than the Sa group (1152.36 N ± 180.89 N). Most failures were adhesive and included irreparable fractures of the crown. CONCLUSION: HA coating after sulfonation effectively enhances the fatigue strength of PEEK abutments veneered with resin composites for implant-supported provisional crowns.