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Published on: June 24, 2018
Human gingival epithelial cell adhesion and proliferation on Ti-6Al-4V surface biofunctionalized with a nanoceramic
Donghyun Kim1, Jennifer Chang1, Harshdeep Bhatia2
1Postgraduate student, Department of Restorative Dentistry, University of Illinois Chicago, Chicago, IL.
Statement Of Problem:
Titanium abutments have been widely used in implant dentistry but exhibit poor soft tissue adhesion, making the crestal bone vulnerable to microbial invasion.
Purpose:
The purpose of this in vitro study was to evaluate the effects of the atomic layer deposition (ALD) of ZrO2-TiO2 nanoceramic thin film coating, with or without ultraviolet C (UVC) irradiation, on grade 5 titanium (Ti-6Al-4V) surface hydrophilicity and the adhesion and proliferation of human gingival keratinocytes.
Material And Methods:
Polished Ti-6Al-4V disks were divided into 3 groups: control (uncoated), ALD (ZrO2-TiO2 coated at 1:4), and ALD-UV (ZrO2-TiO2 coated and UVC-treated). Surface wettability was evaluated via measuring water contact angle (n=5). Telomerase-immortalized human gingival keratinocytes (TIGKs) were cultured on each treated or untreated disk. Cell viability and adhesion were assessed at 6 and 24 hours via fluorescence microscopy (n=7), and proliferation was measured on days 1, 3, and 6 via colorimetric assay (n=7). The cell morphology was examined with scanning electron microscopy (SEM). Statistical analysis was with 1-way ANOVA (water contact angle) and 2-way ANOVA (adhesion and proliferation) with Tukey HSD post hoc tests (α=.05).
Results:
The coating significantly reduced the water contact angle (P<.001), achieving a superhydrophilic surface. Atmospheric aging for 2 and 48 hours increased the water contact angle (both P<.001). Ultraviolet C irradiation post-aging reduced the water contact angle (P<.001) but did not restore superhydrophilicity or enhance human gingival keratinocyte adhesion or proliferation. Cells were viable on the control and coated specimens with or without UVC treatment. All cell densities increased from 6 hours to 6 days (2-way ANOVA effect of time: P<.001), but no significant differences in cell adhesion or proliferation were observed among groups through day 3 (all P≥.58). However, the ALD group showed significantly higher proliferation than the control (P<.001) and ALD-UV (P<.001) on day 6. SEM revealed that TIGKs initially displayed round to spindle-shaped morphologies aligning along nanogrooves during early adhesion at 6 or 24 hours and more flat and round shapes with uniform spreading at days 3 and 6 for all groups.
Conclusions:
Coating Ti-6Al-4V with ZrO₂-TiO₂ thin composite nanoceramic films supported viability and increased proliferation at day 6. The UVC irradiation of the coating improved hydrophilicity but not biological activity.
