Kiyoshi Daito

TNF-α enhances MMP-2 production in deciduous dental pulp fibroblasts

Abstract Inflammation in dental pulp tissue is associated with tissue degradation, and matrix metalloproteinases (MMPs) are believed to participate in this destruction. Elevated levels of some MMPs have been reported in inflamed pulp and periapical lesions. Moreover, in inflamed pulp, many kinds of inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α, are released from inflammatory cells like macrophages, lymphocytes and neutrophils. In the present study, we examined whether TNF-α affected the production of MMP-2 in deciduous dental pulp fibroblasts and its signaling pathways utilizing gelatin zymography and western blotting analysis. TNF-α increased the expression of MMP-2 in a dose-dependent manner in deciduous dental pulp fibroblasts. LY294002 and Wortmannin, which are PI3-K (phosphoinositide 3-kinase) inhibitors, inhibited the MMP-2 production induced by TNF-α in deciduous dental pulp fibroblasts. Moreover, in deciduous dental pulp fibroblasts cultured with TNF-α, AKT (protein kinase B) was phosphorylated in a time-dependent manner with the maximum phosphorylation at 30 min, and LY294002 and Wortmannin abolished this phosphorylation of AKT in TNF-α-stimulated deciduous dental pulp fibroblasts. These results suggest that TNF-α may enhance pulp tissue destruction during pulp inflammation in part by regulating MMP-2, and that the AKT pathway is involved in MMP-2 production in deciduous dental pulp fibroblasts.

An investigation of the special practitioner system of pediatric dentistry in Japan

Abstract We sent questionnaires to all the members (4,298 people) about the specialist pediatric dentistry system in Japan (Hereafter, termed specialists). The survey (1,129 dentists answered the questionnaire) revealed the following: 1.About 29% of the members who have qualifications for pediatric dentists, authorized by Japanese Society of Pediatric Dentistry (JSPD), hoped for a specialist qualification immediately. 2.Eighty point six percent of the members who do not have qualifications authorizing them as pediatric dentists answered that they wanted to take an examination to become a specialist as soon as they were qualified to take it. 3.Many members hoped that the examination to become a specialist would be strictly carried out. 4.Twenty-two point eight percent members thought that the qualifications for pediatric dentists authorized by Japanese Society of Pediatric Dentistry should be abolished after putting the specialist system into effect. 5.Fourteen percent of those that have the qualification of pediatric dentists, authorized by Japanese Society of Pediatric Dentistry, did not want to acquire the specialist title but they wanted to renew their current qualifications. 6.As dentists got older, the ratio of children patients (under 18 years old) tended to decrease. 7.However, about one-quarter, 112 members (about 10% of all) of dentists who are 50–69 years old (347 members) it occupied 34.7% of all treated exceeded 90% children patients.