Due to the high mechanical properties of zirconia, unlike titanium implants, surface modification that matches the material properties of zirconia should be considered. Zirconia was coated with carbonate-apatite thin films by using molecular precursor method. Implantation into the tibia and femoral condyle of rabbits revealed more new bone formation and provided significantly higher bone-to-implant contact (BIC) ratio. Nanosecond pulsed Nd: YAG lasers were irradiated onto two types of zirconia, yttria added type and ceria added type, surfaces to produce regular structure of concave and convex with 30 μm width and 30 μm depth. Implants placement into a rat femoral defect showed a greater degree of bone formation and higher BIC than that of the sandblasted implants. In ceria-added zirconia, there were no clear bone formation and changes in surface composition affected the bone formation.

Early detection of child abuse is an urgent issue. The number of consultations has continued to increase since statistics began. As dental professionals, we need to understand the definition and causes of abuse. It is also important for dentists to be aware of the relationship between the field of dentistry and abuse. In forensic medicine, we learn various things from children who have died from abuse and contribute to early detection for the sake of children living today. Regenerative medicine is also being studied, and it has been reported that new abuse may be stopped through the generation of new neurons.

Currently, pit and fissure sealants are frequently used clinically to prevent dental caries. These pit and fisher sealants are commercially available in Japan after their safety has been evaluated in various biological tests. In three-dimensional culture using type I collagen, cultured cells are contained three-dimensionally within a collagen gel, just like in living tissue. Therefore, it is possible that the results obtained are different from those of cell viability tests using two-dimensional culture. In this study, we compared cell survival rates using the MTT method using two commercially available resin-based and one glass ionomer-based pit and fissure sealants. As a result, for both types of resin-based pit and fissure sealants, a large difference in cell survival rate was observed depending on the light irradiation time, and a low cell survival rate was observed when the light irradiation time was insufficient. Furthermore, the cell survival rate of the glass ionomer-based pit and fissure sealant was slightly lower than that of the resin-based pit and fissure sealant when irradiated with light for 10 seconds. Furthermore, no significant difference was observed between 3 minutes and 5 minutes after mixing. These results reconfirm that when using pit and fissure sealants, it is necessary to pay close attention to the light irradiation time.

Titanium and zirconium have almost no biological problems, and have been widely used in recent dental clinics for implants and aesthetic dentistry. It is necessary to further investigate the biological risks when titanium and zirconium are ionized from the surface and affect surrounding tissues for various reasons in vivo. Therefore, we conducted an investigation using a cell recovery test method in which the toxicity level is determined from the recovery of cells, in which the culture medium to which the material was exposed is removed and then returned to the environment of fresh culture medium. Zirconium ions showed a greater level of cell recovery than titanium ions. Although titanium and zirconium have been shown to have excellent biological safety, when they are ionized in the body due to mechanical stimulation, they are not necessarily biologically safe and secure materials like other metal ions. There is a possibility that this may occur, and further multifaceted biological studies are considered necessary.