An adequate mucosal attachment is important when it comes to preventing peri‐implant inflammation. The aim of this study was to compare epithelial cell adhesion and adhesion protein expression on in sol TiO₂‐coated and non‐coated zirconia and titanium alloy surfaces. Fifty‐six zirconia and titanium discs were cut, and half of them were coated with bioactive TiO₂‐coating. To study the epithelial cell attachment, human gingival keratinocytes were cultivated on discs for 1, 3, 6, and 24 h. The cell proliferation was detected by cultivating cells for 1, 3, and 7 days. In addition, the levels of adhesion proteins laminin y2, integrin α6, β4, vinculin, and paxillin were detected with Western Blot method. Furthermore, high‐resolution imaging of the actin cytoskeleton and focal adhesion proteins was established. Longer‐term cell culture (1–7 days) revealed higher cell numbers on the coated zirconia and titanium discs compared to non‐coated discs. The difference was statistically significant (p < .05) after 24 h on coated zirconia and after 3 and 7 days on coated titanium discs compared to non‐coated discs. Clear induction in the protein levels of laminin y2 and integrin α6 were detected on both coated samples, meanwhile integrin β4 were clearly induced on coated titanium alloy. The microscope evaluation showed significantly increased cell spreading on the coated discs. According to this study, the in sol induced TiO₂‐coating increases keratinocyte attachment and the expression of adhesion proteins on coated zirconia and titanium in vitro. Consequently, the coating has potential to enhance the mucosal attachment on implant surfaces.

Optimal cell adhesion of the gingival fibroblasts to dental implants is important for maintaining good implant integration. The aim of this study was to discover, if the nanoporous TiO₂‐coating on titanium alloy substrates is able to increase the cell adhesion of the human gingival fibroblasts (HGF). The study consisted of three differently produced titanium groups: hydrothermally produced TiO₂‐coating (HT), novel TiO₂‐coating made in sol (SOL), and noncoated control group. Primary HGF cells were initiated from gingival biopsies from patients having a third molar extraction. HGF were cultivated on titanium discs for 2 and 24 h to determine the initial attachment with confocal microscope. The cell spreading and adhesion protein signals were measured. In addition, expression of adhesion proteins vinculin, paxillin, and focal adhesion kinase (FAK) were measured after 3 days of cultivation by using Western Blotting. Higher protein levels of paxillin, vinculin, and FAK were induced on both coated discs compared to noncoated discs. The difference was statistically significant (p < 0.05) concerning expression of paxillin. The cell spreading was significantly larger on SOL discs after 2 and 24 h when comparing to noncoated controls. The confocal microscope analyses revealed significantly higher adhesion protein signals on both HT‐ and SOL‐coated titanium compared to control group. This study showed, that both methods to produce TiO₂‐coatings are able to increase HGF adhesion protein expression and cell spreading on titanium surface. Accordingly, the coatings can potentially improve the gingival attachment to titanium implant surfaces.

The soft tissue-implant interface requires the formation of epithelium and connective tissue seal to hinder microbial infiltration and prevent epithelial down growth. Nanoporous titanium dioxide (TiO₂) surface coatings have shown good potential for promoting soft tissue attachment to implant surfaces. However, the impact of their surface properties on the biological response of gingival cells needs further investigation. This systematic review aimed to investigate the cellular behavior of gingival cells on TiO₂-implant abutment coatings based on in vitro studies. The review was performed to answer the question: “How does the surface characteristic of TiO₂ coatings influence the gingival cell response in in vitro studies?”. A search in MEDLINE/PubMed and the web of science databases from 1990 to 2022 was performed using keywords. A quality assessment of the studies selected was performed using the SciRAP method. A total of 11 publications were selected from the 289 studies that fulfilled the inclusion criteria. The mean reporting and methodologic quality SciRAP scores were 82.7 ± 6.4/100 and 87 ± 4.2/100, respectively. Within the limitations of this in vitro systematic review, it can be concluded that the TiO₂ coatings with smooth nano-structured surface topography and good wettability improve gingival cell response compared to non-coated surfaces.

Establishing a proper soft tissue adhesion around the implant abutment is essential to prevent microbial invasion, inhibit epithelial downgrowth, and obtain an optimal healing process. This systematic review aims to evaluate the real potential of TiO₂ coating on the behavior of peri‐implant soft tissue health and maintenance. A specific aim was to evaluate clinically and histologically the effect of TiO₂ abutment coating on epithelial and connective tissue attachment. Electronic database searches were conducted from 1990 to 2023 in MEDLINE/PubMed and the Web of Science databases. In total, 15 out of 485 publications were included. Eight studies involved humans, and seven were animal studies. Exposure time ranges from 2 days to 5 years. The peri‐implant soft tissue evaluations included clinical assessment (plaque index (PI), peri‐implant probing pocket depth (PPD), and bleeding on probing (BoP)), histological as well as histomorphometric analysis. The Office of Health Assessment and Translation (OHAT) Risk of Bias Rating Tool for Human and Animal Studies was used to evaluate the overall quality of the studies included in the review. The results showed some variation but remained within acceptable limits. Within the limitations of this systematic review, the present findings suggest that TiO₂ coatings seem to influence soft tissue healing. TiO₂‐coated abutments with a roughness value between 0.2 and 0.5 μm enhance soft tissue health. Sol‐gel‐derived TiO₂ coatings induced better soft tissue attachment than noncoated machined abutment surfaces. The anodized titanium abutments demonstrate comparable clinical and histological outcomes to conventional machined abutments. However, there was variation among the included studies concerning TiO₂ coating characteristics and the measured outcomes used to evaluate the soft tissue response, and therefore, quantitative analysis was not feasible. Long‐term in vivo studies with standardized soft tissue analysis and coating surface parameters are necessary before a definitive conclusion can be drawn. OSF Registration No.: 10.17605/OSF.IO/E5RQV.

Bioactive, nanoporous TiO₂-coating has been shown to enhance cell attachment on titanium implant surface. The aim of this study was to evaluate, whether the saliva proteins affect the epithelial cell adhesion on TiO₂-coated and non-coated titanium. Grade V titanium discs were polished. Half of the discs were provided with TiO₂-coating produced in sol with polycondensation method. Half of the TiO₂-coated and non-coated discs were treated with pasteurized saliva for 30 min. After saliva treatment, the total protein amounts on surfaces were measured. Next, the hydrophilicity of discs were measured with water contact angle measurements. Further, the gingival keratinocyte adhesion strength was measured after 2 and 6 h of cultivation using serial trypsinization. In addition, cell growth and proliferation were measured after 1, 3, and 7 days of cell culture. Finally, cell morphology, spreading and adhesion protein signals were detected with high resolution confocal microscopy. As a result, in sol coated TiO₂-surface had significantly higher hydrophilicity when compared to non-coated titanium, meanwhile both non-coated and TiO₂-coated surfaces with saliva treatment had a significant increase in hydrophilicity. Importantly, the amounts of adhered saliva proteins were equal between TiO₂-coated and non-coated surfaces. Adhesion strength against enzymatic detachment was weakest on non-coated titanium after saliva exposure. Cell proliferation and cell spreading were highest on TiO₂-coated titanium, but saliva exposure significantly decreased cell proliferation and spreading on TiO₂-coated surface. To conclude, even though saliva exposure makes titanium surfaces more hydrophilic, it seems to neutralize the bioactive TiO₂-coating and decrease cell attachment to TiO₂-coated surface. Graphical Abstract

This study investigated the impact of the nanocrystalline atomic layer-deposited hydroxyapatite (ALD-HA) coating of titanium (Ti) surface on the attachment and proliferation of human gingival fibroblasts (HGFs). Ti discs were divided into ALD-HA-coated and non-coated (NC) controls. HGFs were harvested from gingival biopsies of patients subjected to extraction of their third molar. The cells were cultivated on the Ti discs for 2 and 24 h to evaluate the initial cell attachment using confocal microscopy. Spreading of cells and the signals of focal adhesion proteins were measured. Moreover, the adhesion proteins vinculin and paxillin expression levels were evaluated using Western blot after 3 d of cultivation. In addition, the proliferation of HGF was assessed by cultivating the cells on Ti discs for 1, 3, and 7 d. Fibroblast spreading was significantly greater on ALD-HA surfaces than on NC surfaces after 2 h (p < 0.001). In addition, the signals of vinculin and paxillin were significantly higher on the ALD-HA than on the NC surfaces at 2 and 24 h. The confocal microscope analysis also revealed significantly higher expression of focal adhesion molecules on ALD-HA surfaces at both time points. Furthermore, the cell proliferation rate was significantly higher at d 3 (p = 0.022) and d 7 (p < 0.001) on the ALD-HA compared to the NC surfaces. These findings indicate that ALD-HA coating enhances focal adhesion formation, cell spreading, and proliferation on Ti surfaces, suggesting its potential to improve gingival tissue attachment to Ti implant surfaces.