Shiro Mataki

Effects of local administration of osteocalcin on experimental tooth movement

The purpose of this study was to evaluate the effects of local administration of osteocalcin, a major noncollagenous bone matrix protein, on experimental tooth movement in rats. An orthodontic elastic band was inserted between the upper first and second molars, and the first molar was moved mesially. Purified osteocalcin (0 to 10 micrograms) in 20 microliters of phosphate-buffered saline was injected into the region of the root bifurcation of the first molar daily for 4 days. Tooth movement increased significantly following the injections. Histological studies revealed that the injections markedly stimulated the appearance of osteoclasts on the pressured side of the alveolar bone surface. The results suggest that osteocalcin has an additive effect on the rate of orthodontic tooth movement through the enhancement of osteoclastogenesis on the pressured side.

Masseter muscle tension and chewing ability in older persons

Aim:  Mastication is an important function to maintain, not only for oral health, but also for quality of life. An easy‐to‐use method to evaluate the chewing ability of elderly people in any environment is necessary. Few studies have discussed the effectiveness of the masseter muscle by palpation. The purpose of this study was to clarify the availability of masseter muscle tension assessment methods by investigating its relationship with oral health status, and comparing it with other methods of assessing chewing ability.

Comparison of the effect of colchicine and vinblastine on the inhibition of dentinogenesis in rat incisors

The quantitative effect of vinblastine, colchicine and lumicolchicine on the rate of dentine formation was determined by chronologically-labelling dentine with the lead salt of EDTA, before and after the intravenous administration of the test drug. Colchicine and vinblastine produced a dose-dependent inhibition of dentine formation. Lumicolchicine had no adverse effect. Although the log dose-response lines of colchicine and vinblastine were parallel, the effect of vinblastine was more potent. The relative potency ratio of vinblastine to colchicine was 1.25-1.70. These results suggest that both colchicine and vinblastine may act at the same site i.e. microtubules, thereby inhibiting the secretion of new dentine matrix.

Expression and localization of ferritin mRNA in ameloblasts of rat incisor

At the maturation stage, the ameloblasts of the rat incisor incorporate iron, supplied through the bloodstream, and deposit it into the surface layer of the enamel. In this unique iron transport system, ferritin functions as a transient iron reservoir in the cells. Here the expression of ferritin mRNA and its localization in the rat enamel organ was examined. Among various tissues, the enamel organ showed the highest expression for both ferritin H- and L-chain mRNA, as quantified by reverse transcription-polymerase chain reaction. In situ hybridization using digoxigenin-labelled cRNA probes for each chain demonstrated that both ferritin H- and L-chain mRNA were abundantly expressed in presecretory and secretory ameloblasts. The intensity of the positive hybridization signal gradually decreased toward the incisal direction. Differing from the mRNA localization, ferritin protein was immunologically undetectable in presecretory or secretory ameloblasts but was found in ameloblasts at the maturation stage, into which iron is known to be incorporated from the bloodstream. Thus, the expression of ferritin mRNA precedes the protein expression in the developmental stages of rat incisor ameloblasts, and the translation of ferritin and its half-life are probably controlled by the iron entry, as has been reported for other cell types.

Effectiveness of an oral health educational program on community-dwelling older people with xerostomia.

The purpose of the present study was to evaluate the changes in oral health and function through an oral health educational program for the independent older people with xerostomia.

Factors associated with self‐rated oral health among community‐dwelling older Japanese: A cross‐sectional study

A cross‐sectional study was carried out to investigate the determinants of self‐rated oral health among community‐dwelling older people in Japan.

Antigenicity of pro-osteocalcin in hard tissue : the authenticity to visualize osteocalcin-producing cells

A polyclonal antibody against rat osteocalcin propeptide (anti-pro-OC) has been prepared and used in immunohistochemical studies to demonstrate cells expressing osteocalcin (OC). With the anti-pro-OC antibody, predominant immunoreaction was observed in cuboidal osteoblasts along the bone formation surface, and in odontoblasts and cementoblasts of the tooth. The appearance of pro-OC antigenicity was well consistent with the expression of OC mRNA in the cells as demonstrated by in situ hybridization. Matrices around these cells showed no apparent pro-OC antigenicity, which contrasted remarkably with the immunoreaction with an antibody against the N-terminal sequence of mature rat OC (anti-OC-N). Although the anti-OC-N antibody positively reacted with OC-producing cells, the intensity of the immunoreaction was much weaker than that obtained with the anti-pro-OC antibody. Furthermore, we examined the appearance of pro-OC antigenicity in maxillary alveolar bone during experimental tooth movement in rats. When the maxillary first molar was moved to the mesial direction with a closed coil spring, the bone remodeling phase in the distal alveolar bone surface changed from dominantly resorptive to formative. After the application of orthodontic force, pro-OC-positive osteoblasts appeared on the distal alveolar bone surface (tension side), according to the appearance of alkaline phosphatase activity on the bone surface. Thus, the use of the anti-pro-OC antibody is a practical means to demonstrate cells actively expressing OC and could be an alternative to in situ hybridization.

歯科医療行動科学における模擬患者 (SP) 実習

The purpose of this paper is to present an outline of students practice of interviewing simulated patients at behavioral science in dentistry. This practice was initiated as part of a newly introduced behavioral science course at our school of dentistry, to enable students to acquire communication skills, comprehensive understanding, and a proper attitude vis-à-vis patients. Students as well as instructors involved in the practice evaluated it as highly relevant for clinical education. It is concluded that the development of such practices in dental education is a prerequisite for training students to dentists oriented toward patient-centered dental practice.

Processing of NH2- and COOH-terminal peptides of rat osteocalcin by cathepsin B and cathepsin L

Abstract: Rat osteocalcin was subjected to proteolysis by cathepsins B and L at acid pH in vitro. Short fragments of fewer than 8 amino acids were liberated from both the NH2- and COOH-termini of the molecule, but the midportion, composed of antiparallel α-helical domains, was resistant to proteolysis. Intact rat osteocalcin bound 10 Ca2+/mol protein at pH 7.5 and the binding decreased to half that amount at pH 5.0, while the midportion fragment (Ala8-Lys43) bound 4–5 Ca2+/mol protein at both pH 5.0 and 7.5. When COOH-terminal-truncated rat osteocalcin (Tyr1-Lys43) was prepared with lysyl-endopeptidase, it showed nearly the same Ca2+ binding as that of the intact molecule. Our results suggest that proteolytic processing of the terminal sequence of osteocalcin alters its intrinsic Ca2+-binding capacity and that its NH2-terminal sequence is probably involved.

Response to comments on: Development of an oral health-related self-efficacy scale for use with older adults: Letters to the Editor

We were delighted to read the letter by Mansori and Safiri commenting on our recently published article in Geriatrics & Gerontology International. The items we used to construct the Geriatric Self-Efficacy Scale for Oral Health (GSEOH) are independent from those we used to confirm external validity, which have been used in previous studies. Therefore, we believe that this will not lead to over-optimistic estimates. As Mansori and Safiri noted, the interval validity of the GSEOH should be improved if we use independent datasets for constructing and confirmation. The participants were divided into two groups according to computer-generated random numbers. The factor loadings for the one-group GSEOH (0.59–0.99) nearly matched those in our recently published article, and the internal consistency (Cronbach’s alpha) was 0.925. Cronbach’s alpha for the three subscales of oral function, oral hygiene habits and dental visits were similarly high: 0.882, 0.883 and 0.962, respectively. The results of the confirmatory factor analysis using the two-group GSEOH are shown in Figure 1. The content of the three GSEOH subscales is consistent with the exploratory factor analysis model. The goodnessof-fit indices show that the model is acceptable (χ = 423, df = 167, P < 0.001, χ/df = 2.5, comparative fit index = 0.938, goodness-of-fit index = 0.893 and root mean square error of approximation = 0.066). Thus, we conclude that our results did not lead to over-optimistic estimates. We hope our study and the letter by Mansori and Safiri will trigger further research interest, efforts and scientific advances in this field.