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Evaluation of microbial adhesion on 3D-printed zirconia surfaces: Effects of printing angle and layer thickness
Kaibin Wu1, Fangqi Liu2, Jörg Lüchtenborg3
1Department of Prosthodontics, School and Hospital of Stomatology, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Guangzhou Medical University, China; Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, China.
Objectives:
The present study investigated how printing angle and layer thickness influence the surface characteristics and initial microbial adhesion to zirconia fabricated via digital light processing (DLP).
Methods:
A total of 156 zirconia specimens were fabricated and divided into six groups based on two layer thicknesses of 30 and 50 μm and three build angles of 0°, 45°, and 90°. The surface topography and roughness were analyzed using scanning electron microscopy and laser scanning microscopy, respectively. The surface wettability was evaluated via water contact angle measurements. The initial adhesion of Streptococcus gordonii (S. gordonii) was assessed by colony-forming unit counts (n = 6). Two specimens per group were fixed, dehydrated, and examined for biofilm observation by scanning electron microscopy. Two-way ANOVA and Tukey multiple comparison tests were conducted. Statistical significance was set at p < 0.05.
Results:
The layer thickness and build angle significantly affected surface roughness (arithmetic mean height, Sa) and water contact angle (degree) values (p < 0.05). SEM analyses revealed that microbial colonies predominantly accumulated in grooves at a 45° build angle. Quantitative assessments demonstrated that printing angle (F(2, 102)=31.68, p < 0.0001) and layer thickness (F(1, 102)=15.74, p = 0.0001) significantly affected S. gordonii adhesion.
Conclusions:
Printing layer thickness and build angle significantly influenced DLP-printed zirconia's surface roughness and water contact angle. Furthermore, they significantly impacted the adhesion of S. gordonii to zirconia surfaces.
Clinical Significance:
Proper build angle and layer thickness are crucial for optimizing the surface morphology and roughness of 3D-printed zirconia since they affect microbial adhesion. Optimal zirconia applications, especially for transgingival surfaces, are achieved using a 0° printing angle and minimizing layer thickness, improving the clinical outcomes.
