Alterations in color stability and anti-biofouling properties of various computer-aided design and computer-aided manufacturing glass-ceramics following ultraviolet weathering aging.

Objectives: This study is aimed to investigate ultraviolet weathering (UW) aging influences the optical, mechanical, and surface behaviors, as well as microbial adhesion, of computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramics.

Methods: A total of 270 specimens from feldspar-reinforced aluminosilicate (VITABLOCS Mark Ⅱ; B), leucite-reinforced (IPS Empress CAD; E), lithium disilicate (IPS e.max CAD; M, Initial LiSi Block, L), and zirconia-reinforced lithium silicate (Celtra Duo; C, VITA SUPRINITY PC; V) glass-ceramics were analyzed. The specimens were subjected to different UW aging conditions (first-aged and second-aged). The optical, mechanical, surface, and anti-fouling properties were evaluated experimentally, followed by statistical analyses of the data (α=0.05).

Results: B and E showed the least color change (P < 0.05), whereas the other materials remained within clinically acceptable limits. Nanoindentation hardness and Young's modulus decreased significantly (P < 0.05), except for E, which demonstrated no significant changes. Vickers hardness exhibited a significant decrease during aging (P < 0.05). Surface roughness increased significantly across all groups, particularly in V (P < 0.05). Surface characteristics revealed microstructural alterations attributed to particle loss and compositional changes. M exhibited the least water contact angle and bacterial adhesion after aging (P < 0.05). UW aging enhanced surface hydrophilicity and subsequently decreased bacterial adhesion owing to the hydrophobic nature of the biofilms formed by Streptococcus mutans and Enterococcus faecalis.

Conclusions: Feldspar-reinforced aluminosilicate and leucite-reinforced glass-ceramic showed the highest color stability, while lithium disilicate exhibited the least bacterial adhesion after UW aging. Color stability, surface attributes, and bacterial resistance of CAD-CAM glass-ceramics exhibited material-specific and aging-dependent differences.

Clinical Significance: UW aging affects the long-term performance of CAD-CAM glass-ceramics, varying based on the material. Besides clinically acceptable color changes, reduced hardness and increased roughness may impact wear and anti-adhesion of Streptococcus mutans and Enterococcus faecalis. Enhanced hydrophilicity could reduce bacterial adhesion, emphasizing the need to consider aging effects in material selection for prosthetic restoration.