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Dental implants have been widely used to restore missing or damaged teeth. Peri-implantitis is one of the main causes of the implant loss. However, a consensus concerning clinically successful peri-implantitis treatment has not been reached at present. We have newly proposed a treatment method for the peri-implantitis by applying the intraoral laser ablation technique to induce a surface modification of dental implants. In the present study, we investigated the cell adhesion ability of α-tricalcium phosphate (α-TCP) films formed on titanium substrates by an Erbium-Doped:Yttrium, Aluminum, and Garnet (Er:YAG) laser deposition method. Cell adhesion was enhanced by the α-TCP films attached firmly to the substrates using the Er:YAG laser deposition method. This intraoral laser deposition technique can be used to recover the osteointegration ability which was lost by the treatment procedures for peri-implantitis.

Dedifferentiated fat cells (DFAT cells) isolated from adipose tissue have been demonstrated to differentiate into chondrogenic cells in vitro. Nevertheless, an efficient method to facilitate its chondrogenic differentiation is still unexplored, hampering the extensive application of these cells in cartilage regeneration therapies. Here we provide the evidence that supplementation of strontium ions (Sr) in a chondrogenic medium (CM) significantly promotes early chondrogenic differentiation of DFAT cells. Human DFAT cells and the mesenchymal stem cell line (RCB2153) were subjected to the CM supplemented with/without Sr. After 14 days, alcian blue staining intensity significantly increased in DFAT cells, but not in RCB2153, subjected to CM with Sr. mRNA expression analysis revealed that the CM with 1.5 mM Sr increased the expression of chondrogenic marker, collagen type 2 alpha 1, whereas there was no significant change in osteogenic markers, collagen type 1 alpha 1, runt-related transcription factor 2, and osteocalcin, and hypertrophic chondrogenic marker, collagen type 10 alpha 1. Inhibitors for extracellular signal-regulated kinase 1/2 (ERK1/2), Akt, and calcium-sensing receptor (CaSR) pathways significantly diminished the alcian blue staining intensity, providing the first evidence that these signal pathways are associated with chondrogenic differentiation of DFAT cells. CaSR and ERK1/2 pathways independently induced Sr-mediated early chondrogenic differentiation. These results suggest that Sr supplementation into the CM may provide a powerful platform for preparing chondrogenically differentiated DFAT cells for cartilage regeneration.

Once tooth decay reaches to the inside of dentin, the damage remains permanently. Therefore, the restoration of dentin is important in dental treatment. In the present study, we newly proposed a tooth restoration technique with intraoral laser ablation method. A thin layer of a-tricalcium phosphate (a-TCP) was deposited on dentin surface in the atmosphere by ablation phenomenon using an Er:YAG (Erbium: Yttrium-Aluminium-Garnet) laser irradiated to the target of a-TCP. Then, the deposited layer was hydrolyzed by dripping pure water on its surface in order to create hydroxyapatite (HAp) coating. Interface structure between the HAp coating and dentin surface was observed by a scanning electron microscope. Electron micrographs showed that the HAp layer of 10-20 mm in thickness was formed on the dentin surface. Moreover, dentinal tubules were sealed with the HAp particles. These results indicate that our newly proposed technique is useful for the treatment of dentin cavities.

To develop a better surface conformation of titanium dental implants, we examined the in vitro biocompatibility of a thin natural apatite (NA) film deposited by laser ablation. Thin (2000-Å) hydroxyapatite (HA) and NA films were deposited on titanium discs using an ArF excimer laser operating at a repletion rate of 10 Hz and annealed by heating at 360°C for 1 h. Energy dispersive analysis of the NA film revealed peaks of Na and Mg in addition Ca and P. X-ray diffraction showed that crystalline HA was present in the HA and NA films. Primary mouse osteoblast grew faster and had higher alkaline phosphatase activity when grown in NA films than on HA films or a bare titanium surface. In addition, osteocalsin production by these cells was higher on HA and NA than bare titanium, but there was no significant difference between cells grown on HA and NA. Thus surface modification with NA film may contribute to successful osteoblast function and differentiation at titanium interface.

To develop a better surface conformation of titanium dental implants, we examined the in vitro biocompatibility of a thin natural apatite (NA) film deposited by laser ablation. Thin (2000-Å) hydroxyapatite (HA) and NA films were deposited on titanium discs using an ArF excimer laser operating at a repletion rate of 10 Hz and annealed by heating at 360°C for 1 h. Energy dispersive analysis of the NA film revealed peaks of Na and Mg in addition Ca and P. X-ray diffraction showed that crystalline HA was present in the HA and NA films. Primary mouse osteoblast grew faster and had higher alkaline phosphatase activity when grown in NA films than on HA films or a bare titanium surface. In addition, osteocalsin production by these cells was higher on HA and NA than bare titanium, but there was no significant difference between cells grown on HA and NA. Thus surface modification with NA film may contribute to successful osteoblast function and differentiation at titanium interface.