Biaxial flexural strength of nanoglass and multiwalled carbon nanotubes reinforced 3D-printed denture base resins and their shear bond strength to 3D-printed and acrylic denture teeth

Objective

Evaluation of biaxial flexural strength (BFS) of nanoglass (NG) and multiwalled carbon nanotubes (MWCNTs) reinforced 3D-printed denture base resins and their shear bond strength (SBS) to 3D-printed and acrylic denture teeth.

Methods

Silanized NG and MWCNTs were added to 3D-printed denture base resin to obtain four groups: Control, 0.25 wt% NG, 0.25 wt% MWCNTs, and a combination group with 0.25 wt% of both fillers. All specimens were tested before and after 600 cycles of thermal aging. BFS (n = 88) was tested using disk-shaped specimens (12 ×2 mm) centralized on an O ring in a universal testing machine. Weibull analysis was conducted to assess predictability of failure. SBS (n = 176) was tested for acrylic and 3D-printed denture teeth attached to bar-shaped specimens in a universal testing machine followed by failure mode analysis using stereomicroscope. Two and three-way ANOVA tests followed by Tukey post hoc test were conducted for BFS and SBS. Kruskal-Wallis test compared percent change among groups with subsequent Dunn post hoc test with Bonferroni correction (α = 0.05).

Results

BFS was affected significantly by filler content (P < 0.001) and thermal cycling (P < 0.001), with thermal cycling displaying the uppermost effect (Ƞp² =0.551). A significant interaction between filler content, thermal cycling, and teeth type was displayed by SBS results (P < 0.001, F=10.340, Ƞp² =0.162). The highest BFS values belonged to 0.25 % MWCNTs while the highest SBS to printed teeth was displayed by the combination.

Significance

The combination group displayed higher BFS and SBS to printed teeth compared to control which allows 3D-printed materials to have a long-term clinical success.