Junko Hayashizaki

Relationships between mandibular cortical bone measures and biochemical markers of bone turnover in elderly Japanese men and women

OBJECTIVE The aim was to clarify the association between dental panoramic radiography measures of mandibular inferior cortical shape and biochemical markers of bone turnover in elderly men and women. STUDY DESIGN Subjects were 80-year-old men (n = 85) and women (n = 153). Mandibular cortical shape and width were evaluated on dental panoramic radiographs. Bone formation and resorption, respectively, were estimated by serum levels of carboxy-terminal propeptide of type I collagen (PICP) and serum type I collagen carboxy-terminal telopeptide (ICTP). RESULTS Eroded cortices of the mandible were significantly associated with increased serum PICP levels (P = .005) in women. Lower mandibular cortical width quartiles were also significantly associated with increased serum PICP levels in men (P = .020) and women (P = .006). CONCLUSIONS Mandibular inferior cortical measures detected on dental panoramic radiographs may be associated with bone formation rates and be useful in predicting osteoporosis in elderly Japanese men and women.

Fluoride profiles in dental calculus from Japanese, Chinese and British residents

Whether the fluoride concentrations and profiles differ in human dental calculus obtained from different countries was investigated. A total of 203 dental calculus deposits on 203 permanent teeth from residents (mean age, 52.1 years) of Nagoya (Japan), Shanghai (China), Leeds (Great Britain) and the Wuhan mountainous area (China, fluoridated area) were analysed. An abrasive microsampling procedure was used to examine fluoride distribution. There were five types of fluoride profiles in dental calculus in each area/country (designated types L, J, U, T, W). In supragingival calculus, type L (highest in the outermost layers) and type J (highest in the innermost layers) both had significantly higher values than type U (high in the surface and innermost layers) but were relatively identical. In subgingival calculus, type W (high in the outermost, mid and innermost layers) was characteristics. Calculus from the Wuhan mountainous area (fluoridated) had the highest fluoride concentration, followed by Leeds (non-fluoridated), and Nagoya and Shanghai (non-fluoridated) calculus had the lowest. Fluoride concentrations in supragingival calculus were higher in teeth extracted because of periodontal diseases than dental caries. It is concluded that fluoride concentrations and distribution in dental calculus differ from country to country, probably due to different fluoride environments.

Preparation of Hydroxyapatite Fiber by using Alginate and its Application to Bioceramics

ABSTRACT Hydroxyapatite fibers were prepared by a reaction of ion exchange of potassium alginate. To investigate the biocompatibility of the hydroxyapatite fibers, surface changes of these fibers were investigated in vitro and in vivo. In vitro experiment: the fibers were immersed in distilled water and a simulated body fluid (SBF) at 37°C for 9 weeks. After immersion, many voids were observed on the surface of the fibers in distilled water, whereas, the small flake-like particles precipitated on the surface of the fiber and the micro-pores were partially formed around the grain boundary in the SBF. In vivo experiment: diffusion chambers filled with these fibers were implanted in subcutaneous tissue of rats. At 3 weeks after implantation, small pores and granular precipitates were observed on the surface of the fibers covered with fascia. These results suggest that the hydroxyapatite fibers are useful biocompatible ceramics which are especially suitable for filling materials.

Fluoride and magnesium concentrations in human dental calculus obtained from Japanese and Chinese patients

Calculus deposited on a total of 68 permanent teeth from patients 30-60 years old from Nagoya in Japan and Beijing in China was investigated. An abrasive microsampling method was used to examine the fluoride (F) and magnesium (Mg) distribution, using a fluoride ion-specific electrode and atomic absorption spectrophotometry, respectively. F concentrations decreased from the surface towards the interior of the calculus. Mg concentrations, however, gradually rose towards the innermost surface adjacent to the tooth. In all parts of the depth profiles, the average concentrations of both magnesium and fluoride were higher in the Japanese than in the Chinese calculus. Towards the inner surface of the calculus, F and Mg concentrations were also much higher in the Japanese than in the Chinese group. A greater intake of sea foods and greater use of fluoride dentifrices are possible reasons for the higher F and Mg concentrations in the Japanese individuals.