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Biomedical subjects

H Mayanagi

Publications and source records attributed to H Mayanagi.

31 records · Page 2Linked to original sources
PubMed1997

Development of interglobular dentine in rat molars and its relation to maturation of enamel.

The development of interglobular dentine in the first upper and lower molars of Wistar rats aged 3, 7, 14, 21, 42 days was examined histochemically using a lectin, succinyl wheat germ agglutinin (sWGA), which is specific for N-acetyl-D-glucosamine. sWGA stained the interglobular dentine, predentin and Golgi area of odontoblasts. Interglobular dentine was not formed in the first molars of 3-day rats, but appeared in those of 7-day rats near the enamel-free area. In 14-day rats, interglobular dentine was present in most areas of the coronal dentine except the cervical area. At the interface between dentine and predentin, numerous sWGA-negative calcospherites were seen, suggesting that the interglobular dentine is formed actively there. In 21-day rats, the interlobular dentine was more numerous than in 14-day rats. Interglobular dentine was present in the cervical root dentine as well as in the coronal dentine, including the cervical area. The distribution of interglobular dentine in 42-day rats was similar to that in 21-day rats, but fluorescence of sWGA binding was less intense in the former. Because the development of interglobular dentine appeared to be time and position specific its relation to the stages of ameloblasts was analysed. Thin enamel matrix was formed at cusps in molars of 3-day rats and thickness of enamel matrix increased in 7-day rats. In these teeth, the ameloblasts were at the differentiating or secretory stage. The Golgi area and Tomes' processes of the secretory ameloblasts, the cells of intermediate layer and the enamel matrix were weakly positive with sWGA. The epithelial cells at the enamel-free area were also stained with sWGA. In 14-day rats, most of the ameloblasts in the first maxillary molars were at the maturative stage except in the cervical area, where the ameloblasts were at the transitional stage. sWGA stained the distal border and the Golgi area of the maturative ameloblasts as well as the cells of the papillary layer. The distal border of the maturative ameloblasts appeared either thick or thin, suggesting a ruffle-end and smooth-end of the cells. Ameloblasts were absent in the first molars of 21-day rats and the cervical part of the enamel was covered with the stratified epithelium like that of 42-day rats. The present study has demonstrated that interglobular dentine contains sWGA-binding glycoconjugates and the formation of the interglobular dentine is largely associated with the enamel maturation. These results suggest that matrix-to-cell interaction is important for the development of interglobular dentine.

Acetylglucosamine↗
PubMed1995

Cross-sectional comparisons of caries time trends in nursery school children in Sendai, Japan.

The aim of this study was to clarify the trends in caries experience in the primary dentition of nursery school children in Sendai, Japan, over a period of 20 yr. An annual clinical dental examination of children aged 2-5 yr at 13 nursery schools in Sendai City was carried out in 1972, 1977, 1982, 1987 and 1992. Data obtained from all five surveys were compared in each age group respectively. The percentages of 2-, 3- and 4-yr-olds free from caries increased remarkably until 1977, while that in 5-yr-olds started increasing several years later. After such increments, percentages in all age groups except 3-yr-olds remained almost at the same level with slight fluctuations. The mean deft and defs values per child in 2-, 3- and 4-yr-olds decreased remarkably until 1977, but then remained almost at the same level thereafter. That in 5-yr-olds continued decreasing slightly during the 20-yr period. The marked reduction of caries experience in nursery school children shown during the 1970's did not continue through the 1980's or the beginning of the 1990's.

Child, Preschool↗
PubMed1990

[Changes of the arch form and occlusion of the deciduous open bite cases: a longitudinal study].

The purpose of this study was to determine the characteristics and longitudinal changes of the arch morphology and occulusion of the deciduous open bite cases. The materials used in this study were the serial plaster casts of 40 Japanese children with deciduous open bite, and they were measured with the three dimentional system. The following results were obtained: 1. The form of dental arch with open bite in the early primary dentition changed remarkably in the maxilla but little in the mandible. In children with open bite, the maxillary intercanine distance was narrower, the maxillary arch length was longer, the palatal height of the front area was higher, but the back one was lower, and the upper central primary incisors were located more forward and upward higher than in children without open bite. 2. In the late primary dentition, the dental arch shape in the spontaneous closure group showed little difference from the control group. However the deciduous upper central incisors of the spontaneous closure group were very remarkably inclined to the palatal side, and the vertical over-jet was larger than that in the control group. The larger the horizontal over-jets were in the early deciduous dentition, the larger the vertical over-jet changed in the late deciduous dentition. 3. In the spontaneous closure group, the point of the dental arch showed a regular changing aspect, in which place marked variation was recognized in the early deciduous dentition as compared with the control group. Because of spontaneous closure, the dental arch shape approached the one of control group rapidly. 4. The result of multivariate analysis indicate that not only discontinuance of thumb-sucking but also many variables of the dental arch shape and occlusal condition may induce spontaneous closure of the open bite within the deciduous dentition term.

Child↗
PubMed1989

[Investigation into the actual condition of outpatients. I. The environmental and oral health status prior to and at the first visit. Comparison of the results between present study and last investigation].

The purpose of this paper was to investigate the actual status of environmental and oral health conditions prior to and at the first visit of the outpatients who visited the pedodontics clinic of Tohoku University Dental Hospital during the period from April 1981 to May 1986, and to compare them with the results of the same kinds of investigation carried out 10 years ago. The subjects were 895 children, with questionnaires being filled out by their mothers. The following results were obtained. 1) As to methods of nursing, breast feedings have increased, while bottle feedings have decreased. The weaning period of almost all of the children was a period between 3 and 6 months of age, as the same as found during the last investigation. 2) The number of children who had eating and drinking habits at bedtime decreased relatively compared with the last investigation. 3) The majority of the children ate between meals twice a day regularly, eating fruits, senbeis (rice crackers), potato chips, and drinking milk frequently. These tendencies in the present study were almost the same as the results of the last investigation. 4) The number of children brushing more than twice a day has been increased compared with the last investigation, and most of them have been brushing their teeth after breakfast and before going to bed. 5) About 87% of the mothers of the patients thought that dental caries are an illness, but 8.9% of them did not. 6) As to caries prevention at home, the majority of the mothers were concerned about tooth-brushing habits and eating habits between meals. In conclusion, this study indicated that concern about oral health of mothers has increased in recent years.

Attitude to Health↗
PubMed1989

[Investigation into the actual condition of outpatients. II. Correlation between the daily habits of eating and toothbrushing and the prevalence of dental caries incidence].

The purpose of this paper was to investigate the correlation between the daily habits of eating and tooth-brushing and the prevalence of dental caries in the outpatients who visited the Pedodontics Clinic of the Tohoku University Dental Hospital during the period from April 1981 to March 1986. The subjects were 877 individuals with questionnaires which the mothers had filled out. The following findings were obtained. 1) The dft index for children aged 1 year to 6 years in the present investigation was lower than that of the same age group investigated 10 years ago. 2) The dft indicies according to each feeding group were 8.86 in the bottle feeding group, 7.51 in the breast feeding group and 6.77 in the mixed feeding group. 3) The group in which the weaning period was late showed a significantly high dft index. 4) The dft index of the group taking beverages containing sugar before going to bed was significantly higher than that of the group without doing this. 5) The group of patients aged 2 years to 5 years who had between-meal snacks more frequently showed a high dft index. 6) The irregularity of the between-meal eating times caused a high tendency toward caries occurrence. 7) The group having between-meal snacks while playing showed a significantly higher dft index than that of the group having it at a table and not playing. 8) No relation was observed between the frequency of tooth brushing and the dft index.

Breast Feeding↗
PubMed1989

[Clinical evaluation of low viscosity composite resin].

This study was to evaluate clinically low viscosity composite resin. The subjects of the present study were 121 children aged 2 to 10 years who visited the Pedodontic clinic of Tohoku University Dental Hospital and 53 children aged 2 to 8 years who visited the clinic of the general practitioners in Sendai. A total of 451 cavities (343 at the clinic of the University Hospital, 108 at the clinic of the general practitioners) were treated with Clearfil SC-II (Kuraray). The observation period varied from 1 month to 33 months after treatment. The restorations were examined with regard to spacing or stepped abrasion in the marginal region of the fillings, fracture, loss, attrition and discoloration of the fillings, and recurrent caries and/or pulpal involvement of the treated teeth. The following findings were obtained. 1) The restoration cases treated at the clinic of the University Hospital were evaluated as clinically acceptable in 254 cases (74.1%), while those treated at the clinic of the general practitioners in 76 cases (70.4%). 2) Of the 343 restorations treated at the clinic of the University Hospital, 73 (21.3%) exhibited poor restorative conditions, while of the 108 restorations treated at the clinic of the general practitioners, 15 (13.9%) showed such conditions. 3) The incidences of poor restorative conditions for anterior restorations were 39.7% and 8.3% respectively at the clinics of the University Hospital and general practitioners. 4) The incidences of poor restorative conditions for posterior restoration were 16.9% and 17.7% respectively at the clinics of the University Hospital and general practitioners. 5) Among the poor restorative conditions, the spacing or stepped abrasion and recurrent caries in the marginal region of the restorations occurred more frequently. 6) The incidences of spacing or stepped abrasion and recurrent caries in the marginal region of the restorations increased in the cases of class II and III cavities.

Child↗
PubMed1989

Dental caries in Swedish 4-year-old children. Changes between 1967 and 1987.

The aim of the study was to examine the prevalence of dental caries in 4-year-olds in the town of Umeå in 1987, and compare that data with data from 4-year-olds examined in 1967, 1971, 1976 and 1980/81, using the same diagnostic methods and criteria. The reduction in the mean dmfs value amounting to 75% between 1967 and 1980/81 did not continue up to 1987, but there was an increase in the number of children without caries from 50% in 1980/81 to 58% in 1987. There was also an increase in the proportion of children with 10 or more dmf-surfaces during the same period. The mean value for dmfs remained the same in these years. An analysis was made of the correlation between the frequency of tooth-brushing, use of fluoride toothpaste, snack consumption and the dmfs-value in 1987. A statistically significant difference in mean values for dmfs was found between children who had their teeth brushed greater than or equal to 2/day and less than or equal to 1/day. When fluoride toothpaste was used, the difference was less pronounced. There was no statistically significant difference in the mean intake frequency of snack products among children with and without caries, but a higher proportion of caries-free children was found among those with a low intake frequency of such products.

Child, Preschool↗
PubMedDate not supplied

Cariogenic potential of lactosylfructoside as determined by acidogenicity of oral streptococci in vitro and human dental plaque in situ.

The cariogenic potential of lactosylfructoside [O-beta-D-galactopyranosyl-(1-->4)-O-alpha-D-glucopyranosyl-(1<-->2)-beta-D-fructofuranoside] was estimated by experiments on oral streptococci in vitro and human dental plaque in situ. Lactosylfructoside was unable to support growth of the strains of Streptococcus mutans and S. sobrinus used in this study. However, it was able to support growth of strains of S. sanguis, S. mitis and S. oralis. Acid was produced rapidly by cell suspensions of S. oralis ATCC 10557 incubated with lactosylfructoside. Application of 5% w/v solution decreased the pH of human dental plaque. The minimum pH value was below 5.3. The results suggest that lactosylfructoside is as acidogenic as lactose and could be cariogenic if it is consumed frequently and retained for a long period in the mouth.

Acids↗
PubMedDate not supplied

Synergistic inhibition by combination of fluoride and xylitol on glycolysis by mutans streptococci and its biochemical mechanism.

The purpose of this study was to evaluate the combined inhibitory effect of fluoride and xylitol on acid production by mutans streptococci, Streptococcus mutans NCTC10449 and Streptococcus sobrinus 6715, from glucose under strictly anaerobic conditions at fixed pH 5.5 and 7.0. The bacteria were grown in a tryptone-yeast extract broth under strictly anaerobic conditions (N2: 80%; H2: 10%; CO2: 10%). Reaction mixtures for acid production from glucose contained bacterial cells with fluoride (0-6.4 mM) and/or xylitol (60 mM). Acidic end products of glucose fermentation and intracellular glycolytic intermediates were assayed. The combination of fluoride and xylitol inhibited acid production more effectively than fluoride or xylitol alone. In the presence of fluoride and xylitol, the proportion of lactic acid in the total amount of acidic end products decreased, while the proportion of formic and acetic acids increased. Analyses of intracellular glycolytic intermediates revealed that xylitol inhibited the upper part of the glycolytic pathway, while fluoride inhibited the lower part. This study indicates that fluoride and xylitol together have synergistic inhibitory effects on the acid production of mutans streptococci and suggests that xylitol has the potential to enhance inhibitory effects of low concentrations of fluoride.

Cariostatic Agents↗