Comparison of Streptococcus mutans adhesion to polished and glazed surfaces of three CAD/CAM ceramics: an in vitro...

Bacterial adhesion to dental restorations plays a critical role in the development of biofilms, contributing to periodontal disease and implant failure. This study aimed to evaluate the effects of glazing and polishing on the adhesion of Streptococcus mutans to three types of CAD/CAM ceramics: lithium disilicate, zirconia-reinforced lithium silicate, and monolithic zirconia.

In this experimental in-vitro study, 81 ceramic specimens (n = 81) from three types-zirconia-reinforced lithium silicate (VITA Suprinity), lithium disilicate (IPS e.max CAD), and monolithic zirconia (InCoris ZI)-were prepared by polishing, glazing, and left untreated as controls. The bacterial adhesion of Streptococcus mutans was assessed using the crystal violet biofilm assay. Following a 48-hour incubation, optical density (OD) values were measured to quantify bacterial adhesion. Scanning electron microscopy (SEM) was used for additional biofilm visualization. The data were analyzed using SPSS software with the Kolmogorov-Smirnov test, one-way and two-way ANOVA, and Tukey test with a significance level of 0.05.

Polished InCoris ZI demonstrated the lowest bacterial adhesion (0.14). Two-way ANOVA revealed a significant interaction between ceramic type and preparation method (p = 0.003), although neither factor alone showed a significant effect. InCoris ZI exhibited significantly higher bacterial adhesion with glazing compared to polishing (p = 0.005), while no significant differences were observed for Suprinity or IPS e.max across preparation methods. Bacterial adhesion to InCoris ZI among glazed samples was significantly higher than Suprinity (p = 0.01) and IPS e.max (p = 0.009).

Preparation methods generally did not significantly influence bacterial adhesion, except for InCoris ZI, where polishing resulted in substantially lower adhesion compared to glazing.

The study highlights that polishing, particularly for InCoris ZI ceramics, effectively minimizes bacterial adhesion, offering a practical alternative to glazing for in-mouth restoration adjustments. By eliminating the need for laboratory processing, polishing can streamline clinical workflows and reduce chairside time, while still maintaining favorable outcomes. These findings emphasize the importance of selecting appropriate surface treatments to enhance the longevity and hygiene of ceramic restorations.