Bond strength of recently introduced computer-aided design and computer-aided manufacturing resin-based crown...

Several additively and subtractively manufactured resin-based materials indicated for interim and definitive fixed dental prostheses have been launched. However, knowledge of the bond strength of these materials to different implant abutment materials is limited.

The purpose of this in vitro study was to evaluate the shear bond strength (SBS) of additively and subtractively manufactured resin-based materials to different implant abutment materials.

One hundred and ten disk-shaped specimens (Ø3×3 mm) were fabricated either additively from 2 resins indicated for definitive use (Crowntec; AM_CT and VarseoSmile Crown Plus; AM_VS) and 1 resin indicated for interim use (FREEPRINT temp; AM_FP) or subtractively from a nanographene-reinforced polymethyl methacrylate (G-CAM; SM_GC) and a high-impact polymer composite (breCAM.HIPC; SM_BC). After allocating 2 specimens from each group for scanning electron microscope evaluation, the specimens were divided according to the abutment material (CopraPeek; polyetheretherketone, PEEK and Dentium Superline Pre-Milled Abutment; titanium, Ti) (n=10). All specimens were airborne-particle abraded with 50-µm aluminum oxide. After applying a resin primer (Visio.link) to PEEK and an adhesive primer (Clearfil Ceramic Primer Plus) to Ti specimens, a self-adhesive resin cement (PANAVIA SA Cement Universal) was used for cementation. All specimens were stored in distilled water (24 hours, 37 °C), and a universal testing device was used for the SBS test. SBS data were analyzed with 2-way analysis of variance and Tukey honestly significant difference tests, while the chi-squared test was used to evaluate the difference among the abutment-resin pairs in terms of failure modes (α=.05).

The interaction between the material type and the abutment type and the main factor of material type affected the SBS (P<.001). SM_BC-PEEK and SM_GC had the lowest SBS followed by SM_BC-Ti, whereas AM_VS-PEEK had the highest SBS (P≤.001). AM_CT-Ti had higher SBS than AM_FP-PEEK (P=.026). SM_GC had the lowest and AM_VS had the highest SBS, while AM_CT and AM_FP had higher SBS than SM_BC (P≤.004). The distribution of failure modes was significantly different among tested material-abutment pairs, and only for AM_CT among tested materials (P≤.025). Most of the material-abutment pairs had a minimum of 80% adhesive failures.

Regardless of the abutment material, additively manufactured specimens had higher bond strength and one of the subtractively manufactured materials (SM_GC) mostly had lower bond strength. The abutment material had a small effect on the bond strength. Adhesive failures were observed most frequently.