Effects of low‐pressure plasma and ytterbium fiber laser on zirconia surface properties and bond strength to gingiva‐colored composite
Merve Akbulut, Ülkü Tuğba Kalyoncuoğlu, Bengi Yilmaz ErdemliAbstract
Purpose
To evaluate and compare the effects of surface activation by low‐pressure plasma (LPP) and surface texturing by ytterbium fiber laser (YFL) treatments on zirconia surface properties and shear bond strength (SBS) to a gingiva‐colored indirect composite under aged and non‐aged conditions.
Materials and Methods
Sixty zirconia specimens were prepared, polished, sintered, and air‐abraded under standardized conditions. The specimens were randomly assigned to three groups according to the applied surface treatment: control, LPP, and YFL. Surface roughness and contact angle were measured before and after surface treatments. A gingiva‐colored indirect composite was bonded to the zirconia surfaces using an 10‐Methacryloyloxydecyl dihydrogen phosphate (MDP) containing primer and standardized mold. Each group was further divided into aged and non‐aged subgroups ( n = 10). Thermal aging was performed using thermocycling (5000 cycles, 5°C–55°C). SBS was measured, and failure modes were analyzed. Surface morphology, phase composition, and representative failure modes were evaluated using scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analyses.
Results
Surface treatments influenced zirconia wettability, with LPP showing a greater reduction in contact angle compared to YFL. YFL groups exhibited higher SBS values than both LPP and control groups under both aged and non‐aged conditions. Thermal aging showed a significant overall effect on SBS, although no significant differences were observed between aged and non‐aged specimens within each surface treatment group. Failure modes were predominantly adhesive in low‐strength groups, whereas mixed failures were more frequent in high‐strength groups.
Conclusion
YFL enhanced bond strength at the zirconia and gingiva‐colored composite interface compared to LPP, whereas aging showed a small but significant overall effect on bond strength, with no significant interaction between aging and surface treatment.