Influence of Surface Treatment on the Physical Properties and Biofilm Formation of Zirconia- Reinforced Lithium Silicate Ceramics: In Vitro Trial.

Purpose: To evaluate the performance of fully crystallized zirconia-reinforced lithium silicate (Celtra Duo, ZLS-CD), partially crystallized zirconia-reinforced lithium silicate (Vita Suprinity, ZLS-VS), and partially sintered lithium disilicate-based (IPS e.max CAD, LD) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging.

Material and methods: Samples of each glass-ceramic material were subjected to polishing with rubber cups (POL), glazing (GL), or no treatment (control: unpolished) and afterward aged with 18,000 thermal cycles (5.C to 55.C). The average roughness, 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated with atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and the flexural strength test (n = 10), respectively. Data were analyzed using two-way ANOVA and Tukey test (α = 5%).

Results: POL produced lower surface roughness than GL, and ZLS-CD presented higher roughness than LD (P < .05). Surfaces without polishing displayed higher roughness than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic material. Irrespective of the treatment, the contact angle was higher in the ZLS-CD group, and regardless of the material, there was higher biofilm formation and lower flexural strength of the unpolished compared to the POL or GL ceramics.

Conclusions: POL promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the GL group. In general, ZLS-CD and ZLS-VS showed more similar behavior than LD, which makes ZLS glass-ceramic a good option for indirect restorations.