Effects of Surface Topography of Zirconia on Human Osteoblastic Cells

Objectives: Evaluate the effects on human osteoblast response to zirconia with different surface finish.
Methods: Zirconia powder (TZ-3YSB-E, Tosoh) was uniaxially pressed into 0.75-inch die discs and then prepared into four different surface finishes: (1) As sintered at 1450°C. (2) Mild rough: zirconia was fully sintered then sandblasted with 50 µm Alumina. (3) Moderate rough: zirconia was partially sintered at 700°C then sandblasted with a distance of 6 cm before fully sintered. (4) Rough: zirconia was partially sintered then sandblasted at 3 cm distance before fully sintered. Surface roughness parameters were measured using Zygo NewView 9000 Optical Profiler. Surface characteristics and cell morphology were identified by SEM (Hitachi SU6600). Cell attachment was assessed at 9 hours after seeding and cell proliferation was evaluated at days 7, 14 and 21 with five replicates for both experimental conditions. One-Way ANOVA was performed for statistical analysis.
Results: Surface roughness of As-sintered, Mild rough, Moderate rough and Rough groups were Sa = 0.196 ± 0.048 µm, 0.537 ± 0.067 µm, 2.440 ± 0.843 µm and 4.145 ± 0.479 µm respectively. All four zirconia groups showed an increase in the amount of cell attachment compared to control at which Rough group had the highest with an average of 76577 ± 336 cells and As-sintered group had the lowest with 76278 ± 129 cells (p-value < 0.01). While proliferation showed contrasting results with As-sintered group having the highest proliferation rate of 5.5 folds and the others showing even fewer cells than when assessed at baseline (p-value < 0.01).
Conclusions: Roughened groups showed good signs of initial attachment due to more surface area but drastic differences in surface height hindered the cell's ability to migrate and proliferate. The As-sintered group had the highest proliferation rate.