Light-activated tooth bleaching with a high hydrogen peroxide (HP; H2O2) concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue.

This study was to investigate the effect of biomechanical stimulation on osteoblast differentiation of human periosteal-derived stem cell using the newly developed bioreactor. Human periosteal-derived stem cells were harvested from the mandible during the extraction of an impacted third molar. Using the new bioreactor, 4% cyclic equibiaxial tension force (0.5 Hz) was applied for 2 and 8 h on the stem cells and cultured for 3, 7, and 14 days on the osteogenic medium. Biochemical changes of the osteoblasts after the biomechanical stimulation were investigated. No treatment group was referred to as control group. Alkaline phosphatase (ALP) activity and ALP messenger RNA (mRNA) expression level were higher in the strain group than those in the control group. The osteocalcin and osteonectin mRNA expressions were higher in the strain group compared to those in the control group on days 7 and 14. The vascular endothelial growth factor (VEGF) mRNA expression was higher in the strain group in comparison to that in the control group. Concentration of alizarin red S corresponding to calcium content was higher in the strain group than in the control group. The study suggests that cyclic tension force could influence the osteoblast differentiation of periosteal-derived stem cells under optimal stimulation condition and the force could be applicable for tissue engineering.

For recent years, devices that generate non-thermal plasma (NTP) have been introduced into the field of dermatology. Since NTP has demonstrated strong anti-pathogenic activity with safety of use, NTP was first applied to sterilize the skin surface to aid in the healing of various kinds of skin diseases. However, the effect of NTP on skin regeneration has not yet been fully explored. In this study, the effect of NTP on the growth of keratinocytes was tested using the HaCaT human keratinocyte cell line and HRM2 hairless mice. Treatment with NTP allowed confluent keratinocytes to escape from G1 cell cycle arrest and increased the proportion of cells in S and G2 phases. In particular, NTP treatment immediately dispersed E-cadherin-mediated cell-to-cell interactions, resulting in the translocation of β-catenin to the nucleus and leading to the enhanced transcription of target genes including c-MYC and cyclin D1. Moreover, repeated treatment of the mice with NTP also stimulated epidermal expansion by activating β-catenin in the epidermal cells. The symptoms of cellular DNA damage were not detected after NTP treatment. Taken together, these results demonstrate that NTP may be employed as a new type of skin regenerating device.