Effects of laser modalities on shear bond strengths of composite superstructure to zirconia and PEEK infrastructures: an in vitro study

In the last decade, demand for metal-free esthetic restorations has grown considerably due to the development of materials to fulfill the need for an esthetic prosthesis. We examined the effects of erbium-doped yttrium aluminum garnet (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), and potassium titanyl phosphate (KTP) laser applications on the shear bond strength (SBS) of nanohybrid composite superstructures to zirconia and PEEK infrastructures. Zirconia and PEEK specimens were prepared with CAD/CAM technology in accordance with ISO 11405 standards. The disc-shaped samples were randomly separated into four groups (n = 8) according to applied laser type: no treatment and Er:YAG, Nd:YAG, and KTP lasers. Nanohybrid composite resin was applied as a veneering material to each infrastructure. After surface treatment of infrastructures by the lasers, the SBS test was carried out to determine the bonding of infrastructures, which were also examined with a stereomicroscope. The SBS were significantly higher in the PEEK specimens treated with the studied lasers. Nd:YAG laser was the most effective method, followed by Er:YAG laser and KTP laser. The lowest SBS value was obtained in the no-treatment group. Stereomicroscopically, the studied lasers produced different irregularities on the infrastructures. PEEK as a framework provides meaningfully higher bonding strength to composite resins compared to zirconia. Nd:YAG, Er:YAG, and KTP, in descending order, are efficacious in increasing the attachment of studied structures.

Automated summary

The study showed that laser treatments significantly increased the bonding strength between PEEK specimens and composite resins, with Nd:YAG laser being the most effective. Different laser treatments resulted in various irregularities on the infrastructures.