Ultraviolet Treatment of Titanium to Enhance Adhesion and Retention of Oral Mucosa Connective Tissue and Fibroblasts

Abstract

Peri-implantitis is an unsolved but critical problem with dental implants. It is postulated that creating a seal of gingival soft tissue around the implant neck is key to preventing peri-implantitis. The objective of this study was to determine the effect of UV surface treatment of titanium disks on the adhesion strength and retention time of oral connective tissues as well as on the adherence of mucosal fibroblasts. Titanium disks with a smooth machined surface were prepared and treated with UV light for 15 min. Keratinized mucosal tissue sections (3 × 3 mm) from rat palates were incubated for 24 h on the titanium disks. The adhered tissue sections were then mechanically detached by agitating the culture dishes. The tissue sections remained adherent for significantly longer (15.5 h) on the UV-treated disks than on the untreated control disks (7.5 h). A total of 94% of the tissue sections were adherent for 5 h or longer on the UV-treated disks, whereas only 50% of the sections remained on the control disks for 5 h. The adhesion strength of the tissue sections to the titanium disks, as measured by tensile testing, was six times greater after UV treatment. In the culture studies, mucosal fibroblasts extracted from rat palates were attached to titanium disks by incubating for 24, 48, or 96 h. The number of attached cells was consistently 15–30% greater on the UV-treated disks than on the control disks. The cells were then subjected to mechanical or chemical (trypsinization) detachment. After mechanical detachment, the residual cell rates on the UV-treated surfaces after 24 and 48 h of incubation were 35% and 25% higher, respectively, than those on the control surfaces. The remaining rate after chemical detachment was 74% on the control surface and 88% on the UV-treated surface for the cells cultured for 48 h. These trends were also confirmed in mouse embryonic fibroblasts, with an intense expression of vinculin, a focal adhesion protein, on the UV-treated disks even after detachment. The UV-treated titanium was superhydrophilic, whereas the control titanium was hydrophobic. X-ray photoelectron spectroscopy (XPS) chemical analysis revealed that the amount of carbon at the surface was significantly reduced after UV treatment, while the amount of TiOH molecules was increased. These ex vivo and in vitro results indicate that the UV treatment of titanium increases the adhesion and retention of oral mucosa connective tissue as a result of increased resistance of constituent fibroblasts against exogenous detachment, both mechanically and chemically, as well as UV-induced physicochemical changes of the titanium surface.

A Novel Cell Delivery System Exploiting Synergy between Fresh Titanium and Fibronectin

“…Second, fibronectin adsorbed to titanium surfaces considerably more than type 1 collagen ( Figure 2 ). The role played by surface hydrophobicity/hydrophilicity in material biocompatibility, including for titanium, remains inconclusive, with even the basic hypothesis that more hydrophilic surfaces attach more cells remaining unproven, although some data do seem to suggest this [ 89 , 90 , 96 , 101 , 102 , 127 , 128 , 129 , 130 , 131 ]. Although UV-induced superhydrophilic titanium surfaces recruit more cells than non-treated hydrophobic titanium surfaces, there was no linear correlation between the degree of hydrophilicity and the number of cells recruited [ 127 ].…”

Human Gingival Fibroblast Attachment to Smooth Titanium Disks with Different Surface Roughnesses

“…Research on the surface properties of titanium, which is an implant body, has thus far focused on improving the bone–implant integration (osseointegration); therefore, research on rough surfaces has been actively carried out. Studies on bone–implant integration range from those investigating the effect of carbon contamination on the titanium surface of the bone formation [ 1 , 23 , 24 ] to those showing enhanced osteoblast activity through the ultraviolet treatment of titanium [ 7 , 8 , 25 , 26 , 27 , 28 ]. However, most of these studies have used titanium, which has a relatively rough surface.…”

Cell Type-Specific Effects of Implant Provisional Restoration Materials on the Growth and Function of Human Fibroblasts and Osteoblasts

“…Depending on the implant position, tissue healing, and prosthetic strategy, the alveolar bone can be in close proximity to provisional restorations. Ideally, the materials used for this transmucosal portion should be nontoxic to the contacting and adjacent tissues and should not induce peri-implant gingival recession and bone loss [ 3 , 4 , 5 , 6 ]. Preferably, the materials should allow peri-implant connective tissue to adhere and form a stable physical barrier to prevent the invasion of oral bacteria, which could jeopardize osseointegration and implant longevity [ 4 , 7 ].…”

“…Ideally, the materials used for this transmucosal portion should be nontoxic to the contacting and adjacent tissues and should not induce peri-implant gingival recession and bone loss [ 3 , 4 , 5 , 6 ]. Preferably, the materials should allow peri-implant connective tissue to adhere and form a stable physical barrier to prevent the invasion of oral bacteria, which could jeopardize osseointegration and implant longevity [ 4 , 7 ]. Thus, prior to delivery of the definitive implant restoration, provisional implant restorations play important roles in establishing anatomical and biophysiological stability and a soft tissue seal during the critical stage of healing [ 8 , 9 ].…”