Effect of finishing/polishing techniques and aging on topography, C. albicans adherence, and flexural strength of ultra-translucent zirconia: an in situ study

• Published in: Clinical oral investigations Vol. 26; no. 1; pp. 889 - 900
• Main Authors: de Carvalho, Isabelle Helena Gurgel, da Silva, Nathalia Ramos, Vila-Nova, Taciana Emília Leite, de Fatima Dantas de Almeida, Leopoldina, Veríssimo, Aretha Heitor, de Melo, Renata Marques, Zhang, Yu, de Assunção e Souza, Rodrigo Othávio
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-01-2022; Springer Nature B.V
• Subjects: Abrasion; Aging; Candida albicans; Cell adhesion; Ceramics; Dental Polishing; Dentistry; Dentures; Flexural Strength; Humans; Kruskal-Wallis test; Materials Testing; Medicine; Microscopy, Electron, Scanning; Original Article; Rubber; Scanning electron microscopy; Statistical analysis; Surface Properties; X-ray diffraction; Zirconia; Zirconium; Zirconia; Biofilm; Aging; Dental ceramics; Polishing; Flexural strength
• ISSN: 1432-6981; 1436-3771
• DOI: 10.1007/s00784-021-04068-3

Objective
To investigate the influence of different finishing/polishing techniques and in situ aging on the flexural strength (
σ
), surface roughness, and
Candida albicans
adherence of 5 mol% yttria-stabilized zirconia (ultratranslucent zirconia).
Materials and methods
A total of 120 zirconia bars (Prettau Anterior, Zirkonzahn) with dimensions of 8 × 2 × 0.5 mm were divided into 8 groups (
n
 = 15) according to two factors: “in situ aging” (non-aged and aged (A)) and “finishing/polishing” (control (C), diamond rubber polishing (R), coarse grit diamond bur abrasion (B), and coarse grit diamond bur abrasion + diamond rubber polishing (BR)). Half of the samples from each group were subjected to a 60-day in situ aging by fixing the bars into cavities prepared in the posterior region of the base of complete or partial dentures of 15 patients. The samples were then subjected to the mini flexural (
σ
) test (1 mm/min). A total of 40 zirconia blocks (5 × 5 × 2 mm) were prepared and subjected to roughness (Ra) analyses and fungal adherence and complementary analyses (X-ray diffraction (XRD) and scanning electron microscopy (SEM)). The data of mean
σ
(MPa) and roughness Ra (μm) were statistically analyzed by two-way and one-way ANOVA, respectively, and Tukey’s test. The Weibull analysis was performed for
σ
data. The fungal adhesion (Log CFU/mL) data were analyzed by Kruskal–Wallis tests.
Results
For flexural resistance, the “finishing/polishing” factor was statistically significant (
P
 = 0.0001); however, the “in situ aging” factor (
P
 = 0.4458) was not significant. The non-aged (507.3 ± 115.7 MPa) and aged (487.6 ± 118.4 MPa) rubber polishing groups exhibited higher mean
σ
than the other techniques. The non-aged (260.2 ± 43.3 MPa) and aged (270.1 ± 48.8 MPa) bur abrasion groups presented lower
σ
. The coarse-grit diamond bur abrasion group (1.82 ± 0.61 µm) presented the highest roughness value (
P
 = 0.001). Cell adhesion was not different among groups (
P
 = 0.053). Group B presented the most irregular surface and the highest roughness Ra of 0.61 m.
Conclusions
The finishing of ultratranslucent zirconia might be preferably done with a diamond rubber polisher. Moreover, the protocols used did not interfere with
Candida albicans
adhesion.
Clinical relevance
Coarse-grit diamond burs might be avoided for finishing ultratranslucent monolithic zirconia, which might be preferably performed with a diamond rubber polisher.