Factors associated with Japanese dentists encouraging patients to use dental floss.

OBJECTIVE: The objective of this study was to clarify to what extent Japanese dentists recommend dental floss and what factors influence dentists in encouraging their patients to use dental floss. PARTICIPANTS: The subjects in this study were 291 dentists who were directors of dental clinics, selected by stratified sampling by age. RESULTS: Dentists whose teachers at dental school had demonstrated dental flossing tended to recommend patients to use dental floss 2.2 (1.0-4.6: 95% CI) times more frequently compared with those who did not see demonstrations of flossing at dental school. Respondents who considered that using dental floss was very easy and easy, moderate, and difficult recommended patients to use dental floss 45.4 (11.2-183.9), 17.4 (6.6-45.8) and 5.9 (2.5-14.1) times more frequently, respectively, compared with those who considered it very difficult. Respondents who considered that using dental floss was effective, fairly effective or very effective in preventing dental caries recommended patients to use dental floss 3.8 (1.7-8.6), 3.8 (1.7-8.8) and 9.1 (3.6-23.0) times more frequently respectively, compared with those who considered it ineffective or only slightly effective. CONCLUSIONS: The demonstration of the use of dental floss by teachers at their dental schools gave dentists a good impression and a positive opinion of dental flossing. This was closely associated with recommendations by dentists to their patients to use dental floss.

Influence of beverage and food consumption on fluoride intake in Japanese children aged 3-5 years.

This study was conducted to estimate the relative contribution of particular foods and drinks to dietary fluoride intake in 94 preschool Japanese children in low-fluoride areas. The mean daily fluoride intake from all beverages (548 +/- 162 g) was 0.108 mg (SD = 0.082), accounting for 37% of the total dietary fluoride; tea beverages showed the highest value, 0.093 mg (SD = 0.081), 32%. That from staple food and side dishes was 0.183 mg (SD = 0.146), 63%, followed by cereals (12%), fish (8%) and bean products (5%). In conclusion, the contribution of beverages excluding tea to dietary fluoride intake is small in Japanese children.

Plasma growth hormone responses to somatostatin (SRIH) and SRIH receptors in pituitary adenomas in acromegalic patients.

The plasma GH response to somatostatin (SRIH) infusion and SRIH receptors in pituitary adenoma cell membranes were investigated in six acromegalic patients. Infusion of 0.3 and 1.0 microgram/kg . h SRIH increased plasma SRIH concentrations in these patients in a dose-related manner. In five of the six patients, mean plasma GH levels decreased to 65.5 +/- 5.0% (+/- SEM) and 43.7 +/- 3.1% of the basal level when 0.3 or 1.0 microgram/kg . h SRIH was infused, respectively. In the remaining patient, plasma GH levels did not change, even when a larger dose of SRIH was infused. High density and specific SRIH receptors, with a mean dissociation constant of 0.92 +/- 0.17 nM and a mean maximal binding capacity of 523.8 +/- 174.6 fmol/mg protein, were identified in GH-secreting adenomas from the five SRIH-responsive patients. On the other hand, in the adenoma from the SRIH-nonresponsive patient, the maximal binding capacity (40.5 fmol/mg protein) was as low as those of nonfunctioning adenomas, as reported previously (undetectable to 48.0 fmol/mg protein). We conclude that the differential responses of plasma GH to SRIH in acromegalic patients may be related to variations in the binding capacity for SRIH in adenoma cell membranes.

Specific somatostatin receptors on human pituitary adenoma cell membranes.

Specific somatostatin (SRIH) receptors on human pituitary adenoma cell membranes were characterized using [125I]Tyr11-SRIH as the radioligand. Specific binding of [125I] Tyr11-SRIH to adenoma cell membranes reached a steady state within 30 min at 25 C, and semilogarithmic analysis of the data revealed that the rate of the binding was linear at 25 C with a t1/2 of 13.2 min. Specific binding increased linearly with 5-160 micrograms plasma membrane protein. SRIH-14 and SRIH-28 inhibited [125I]Tyr11-SRIH binding to adenoma cell membranes with ID50S of 0.32 and 0.50 nM, respectively, while secretin, glucagon, gastrin, cholecystokinin-8, bombesin, TRH, LHRH, human GH-releasing factor-(1-44)-NH2, D-Ala2-met-enkephalin, gamma-aminobutyric acid and taurine did not significantly inhibit binding. All of 13 GH-secreting adenomas investigated had specific and high affinity SRIH receptors, with a dissociation constant (Kd) of 0.80 +/- 0.15 nM (mean +/- SEM) and a maximal binding capacity (Bmax) of 234.2 +/- 86.9 fmol/mg protein (mean +/- SEM). Among five of the nonsecreting pituitary adenomas examined, two had SRIH receptors with Kd values of 0.18 and 0.32 nM and Bmax values of 17.2 and 48.0 fmol/mg protein, respectively. In the remaining three, SRIH receptors were not detected. These results indicate that GH-secreting adenomas as well as some nonfunctioning adenomas have specific SRIH receptors, and hence, the function of the adenomas could be altered by SRIH.

Evidence for the release of a novel pituitary polypeptide (7B2) from the growth hormone-producing pituitary adenoma of patients with acromegaly.

We studied the release of the pituitary polypeptide 7B2 in normal subjects and patients with acromegaly. Plasma 7B2 concentrations did not increase in response to human GHRH and TRH in normal subjects. Plasma 7B2 concentrations significantly increased from 124.4 +/- 39.9 (mean +/- SE) to 206.9 +/- 55.9 ng/L (180.8 +/- 17.9% of the basal value; P less than 0.01) 15 min after iv administration of GHRH in eight acromegalic patients, but they did not increase in nine other acromegalic patients. Mean plasma 7B2 levels increased from 68.8 +/- 17.9 to 168.7 +/- 53.5 ng/L (241.8 +/- 34.2% of the basal value; P less than 0.005) 30 min after iv administration of TRH in four acromegalic patients, but the two other patients tested had no response. No elevations of plasma 7B2 were found after iv administration of ovine CRH in six patients with Cushing's disease and after iv administration of TRH and/or oral administration of bromocriptine in six prolactinoma patients. In experiments using cultured human somatotroph adenoma cells, high K+ induced 7B2 release. The apparent mol wt of 7B2 in plasma was 20,000, whereas that of 7B2 in the culture medium was about 45,000. These findings suggest that 7B2 is secreted by human GH-producing pituitary adenoma cells and that plasma 7B2 responses to GHRH and/or TRH may be characteristics of human somatotroph adenomas.

Distribution profiles of fluoride in three different kinds of rat bones.

The study was performed to reveal the detailed distribution profiles of fluoride in three different kinds of rat bone--humerus, vertebral arch, and parietal bone--and to compare this with the histological appearance of each bone type. Two groups of Wistar rats were provided water ad libitum containing 0 and 100 ppm fluoride, respectively, for 24 weeks. The fluoride distribution profiles across the bone of the three different bones from the outer to the inner surface were determined by means of an abrasive micro-sampling technique. In control animals, both humerus and parietal bones showed higher concentrations at the periosteal and endosteal surfaces, while the vertebral arch showed additional high levels in the middle (containing trabecular bone) of the tissue. In exposed animals, fluoride levels increased greatly in all three bone types. The vertebral and parietal fluoride distribution profiles were relatively unchanged, although humerus fluoride increased from periosteum to endosteum. The differences in fluoride distribution profiles were apparently related to the histological appearances of these bones. The surface area of bone available and the extent of vascularity appear to affect fluoride uptake.

Somatosensory and spinal evoked potentials in patients with cervical syringomyelia.

We recorded somatosensory evoked potentials (SEPs) from the skin surface and spinal evoked potentials (SpEP) from the posterior epidural space after median nerve stimulation in 11 patients with cervical syringomyelia. We compared SEPs with SpEP to assess the possible feasibility of using these techniques to localize the offending lesion. SEP abnormalities were present on one or both sides of 7 patients (9 of 22 upper limbs; 41%). The abnormal SEP pattern was the attenuation or loss of N13, which was of little value for delineating the lesion. In patients with abnormal SEPs, three types of abnormal SpEPs were noted. In the Type A abnormality (three limbs), potentials were attenuated in all cervical segments, suggesting that the syrinx itself had enlarged to involve the posterior column. In Type B (two limbs), there was reduced amplitude or absent upper cervical potentials, probably a result of the accompanying tonsilar herniation. Finally, the Type C (four limbs) abnormality was a mixture of Type A and B abnormalities in that the attenuated cervical potentials were again affected in the most upper cervical segment. We concluded that SpEP revealed various kinds of involvement of the dorsal column pathway in the syringomyelic patients, a finding not expressed with conventional SEPs.

Monkey brain damage from radiation in the therapeutic range.

Twelve Macaca mulatta monkeys received 200 rads of supervoltage radiation to the whole brain per day, 5 days a week. The course in 4 monkeys was 4 weeks for a total dose of 4000 rads; in 4 monkeys, 6 weeks for 6000 rads; and in 4 monkeys, 8 weeks for 8000 rads. Four unirradiated monkeys served as controls. One from each group, sacrificed at 6 and 12 months from start of irradiation, are reported here. The results from 4000 rads were negligible; those from 8000 rads, profound, with gross brain destruction. The results from 6000 rads, within the therapeutic range, included at 6 months punctate necrotic lesions, 1 mm or less, widely scattered but with a predilection for the forebrain white matter. The reaction to these lesions ranged from an early macrophage response to calcification. Some were accompanied by focal edema. There were occasional examples of vascular endothelial proliferation. In addition, there were patches of dilated capillaries or telangiectasia. Twelve months after 6000 rads there were a few mineralized lesions and innumerable minute deposits of calcium and iron. A more active process was suggested by widely disseminated areas of telangiectasia, 6 to 12 mm in extent. The clinical course from this exposure included papilledema from the third to the sixth month and depressed visual evoked response accompanied by delta activity in the electroencephalogram from the sixth to the twelfth month.

Fluoride profiles in different sites of approximal surfaces of second primary molars after topical application of acidulated phosphate fluoride gel in vivo.

Thirty-four (17 paired) extracted second primary molars were obtained from 17 individuals (9 boys and 8 girls) aged from 9 yr 2 months to 12 yr 7 months. A tooth on one side was extracted as a control, and an acidulated phosphate fluoride (APF) gel was then applied to the paired contralateral second primary molar. Three months later, the experimental tooth was extracted. Nine sites were assayed by a microsampling technique from small areas of the approximal enamel surface. The fluoride and phosphorus concentrations were determined by a fluoride electrode and by colorimetric procedure, respectively. Fluoride concentrations were higher in the teeth treated with the APF gel than in the control teeth. The highest fluoride uptake was observed in the central area of the approximal surfaces. Deeper areas (> 10 microns) had a marked uptake of fluoride as compared with surface areas (< 3 microns). It was concluded that the APF gel application increased the fluoride levels of approximal tooth surfaces, particularly the mid-central site, of second primary molars, even at 3 months after application.

Identification of tissue inhibitor of metalloproteinases-1 (TIMP-1) in human teeth and its distribution in cementum and dentine.

An inhibitory activity toward matrix metalloproteinases such as interstitial collagenase, 72-kDa gelatinase/type IV collagenase, and stromelysin-1 was detected in an EDTA extract of pulverized roots of human teeth, and identified as TIMP-1 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and immunoblotting. Distribution of TIMP-1 in human cementum and dentine was investigated by a sandwich enzyme immunoassay in combination with an abrasive microsampling technique. TIMP-1 could not be detected in cementum from some teeth but in others decreased from a fairly low value at the surface towards the cementodentinal junction. TIMP-1 concentrations in the dentine increased consistently from the cementodentinal junction toward the predentine. The average TIMP-1 concentration in the dentine (54.1 +/- 18.5 pg/mg +/- SE) was significantly (P < 0.05) higher than that (9.6 +/- 6.0 pg/mg +/- SE) in the cementum.

Distribution of fluoride across human primary enamel.

The distribution of fluoride was described in detail from the incisal to the cervical region in 10 pairs of primary lower central incisors. Fluoride analyses were done on the right incisors; optical microscopic studies were done on the left. The distribution data obtained from fluoride analyses of the right incisors were superimposed on micrographs of sections through the left incisors. An abrasive microsampling technique (Weatherell et al., 1985) was used to determine the fluoride concentration and distribution. Fluoride concentration was the highest at the enamel surface and decreased from there to the interior. The fluoride distribution did not level off to an even plateau in the enamel interior, as suggested by earlier studies. Apart from the high concentration in the surface region, the fluoride levels in prenatal and postnatal enamel were rather similar. The fluoride concentration tended to be low at the neonatal line.

In vivo fluoride profiles at different sites of buccal and lingual enamel surfaces obtained by enamel biopsy of human maxillary first permanent molars in young adults.

Twenty male volunteers, average age 24 years, participated in this study. Specimens were obtained by enamel biopsy using 5 microliters of 0.5 M HClO4 for 30 s. Using a regression curve, comparisons of fluoride concentrations were made at different depths. The fluoride concentrations (mean +/- SE) at a depth of 5 microns were highest in the distobuccal (1698 +/- 136), high in the mesiobuccal (1343 +/- 122), low in the distolingual (1119 +/- 107), and lowest in the mesiolingual sites (819 +/- 78). Of the interior enamels (> or = 10 microns in depth), the distobuccal site (1330 +/- 88 parts/10(6) F at 10 microns) had a higher-concentration than all other sites. The fluoride profiles were steepest to shallowest in the order: distobuccal, mesiobuccal, distolingual and mesiolingual. There were no correlations between the enamel fluoride concentrations and the fluoride concentration in parotid saliva. It was concluded that in vivo fluoride profiles of maxillary first molars reflect the wear of the tooth surface with age and the condition of dental plaque deposition, and, to some extent, the site-specific distribution of saliva between buccal and lingual surfaces.

Distribution of fluoride in human cementum.

Fluoride and phosphorus concentrations were determined in layers of cementum and dentine serially-abraded from the root surface, passing through the cementum-dentine junction and into the underlying dentine, using silicon carbide-impregnated film. The concentrations of F in the cementum mineral were variable but consistently maximal at or near to the external surface of the root and tending to fall towards the interior and across the cementum-dentine junction into the underlying dentine. The F content in the cementum tended to increase with age.

Distribution of fluoride across human dental enamel, dentine and cementum.

This was determined across the entire width of sections from 20 mandibular premolars, containing enamel, coronal dentine, root dentine and cementum. An abrasive technique was used to sample all three dental tissues in a single experiment. In the profiles of fluoride distribution, fluoride concentration was thus precisely related to the position of the tissue sample. There was a marked increase in the fluoride content of coronal and root dentine, at least until the age of about 50 years. There had been uptake of fluoride by the root dentine and cementum throughout the life of the tooth. There was no evidence of any change in the fluoride content of enamel with age.

The distribution pattern of fluoride concentrations in human cementum.

The distribution of fluoride across human cementum has been determined on 59 individual teeth taken post mortem from five subjects aged 30, 43, 54, 66 and 70 years. Eight teeth of different types were examined from each of the five subjects together with a further 19 teeth from the 54-year-old, making a total of 27 teeth from this subject. As in a previous study, F concentrations were generally higher towards the surface of the cementum, but there were considerable variations between F gradients. The teeth from each subject seemed to comprise a family of profiles, characteristic of the individual.

The dissolution rate of enamel in acid in developing rat incisors.

This study was undertaken to determine the changes in this dissolution rate at different developmental stages after different fluoride dietary regimes. Four groups of Wistar rats received water with 0, 25, 50 and 100 parts/10(6) fluoride respectively for 10 weeks. Six exposed windows of 2 mm2 were prepared on the enamel surface of the upper incisors, corresponding to six different developmental stages. The acid-dissolution rates were determined at each window by using 1.4 M sodium acetate-hydrochloric acid buffer (pH 2.3). The rate of enamel dissolution was highest in the matrix-formation stage and dropped sharply in a step-wise fashion towards the stages of secondary mineralization and iron deposition. The dissolution rate in the maturation stage decreased significantly with increasing intake of fluoride. However, in the pigmented enamel, the opposite occurred. The iron pigmentation or the porosity in this region of fluorosed enamel might be responsible for the change in the dissolution rate of the pigmented enamel.

Differences in fluoride concentrations in the enamel surfaces of lower first premolars from young human males and females.

There are unconfirmed, reported differences in fluoride concentration in the tooth surfaces of male and female children whose average age was 13.5 yr (range 11.5-15.7 yr) and whose teeth might therefore have been exposed for 2-3 yr after eruption to the oral environment. Thirty-two unerupted and 24 erupted mandibular first premolars were now examined. These had been extracted for orthodontic reasons from children aged from 9 to 10 yr. Samples were removed by acid etching from small areas of the enamel surface, and the fluoride and phosphorus concentrations determined with an electrode and by colorimetry, respectively. Three sites on the buccal surface and one site in the centre of the lingual surface were investigated. Fluoride concentrations were higher in erupted than in unerupted enamel. The fluoride concentration of erupted enamel from the female teeth was significantly higher than that of the males (in contrast to the previous findings), although no analogous differences emerged in the fluoride concentrations of the unerupted enamel.

Glucose clearance from different surfaces of human central incisors and first molars.

The study examined the glucose clearance (retention) in saliva at different surfaces of these teeth in 23 subjects. The mouth was thoroughly rinsed for 15 s with 20 ml of a 0.5 M glucose solution. The concentrations of glucose absorbed by small pieces of paper, placed on the mesial, distal, labial (buccal), lingual and occlusal surfaces 3 min after rinsing, were measured using an immobilized enzyme system and an electrochemical sensor. On the maxillary and mandibular central incisors, the glucose concentrations on the labial surfaces were significantly higher than on all other surfaces and lowest on the lingual surfaces. In the mandibular molars, glucose concentrations were significantly higher on the buccal surfaces than on the lingual surfaces. Clear site-specific differences in glucose clearance were thus observed at the different tooth surfaces. It is considered that the differences in the glucose retention rate might be indicative of factors important for the site specificity of dental caries.

Fluoride uptake in human dentine from glass-ionomer cement in vivo.

The purpose was to examine F uptake and distribution in dentine from a F-containing glass-ionomer cement in vivo. Nine volunteers were selected from dental students who were scheduled for extraction of their third molars. Two cavities were prepared on the same occlusal surface of the third molars for each subject; one was restored with glass-ionomer cement (Virtabond), the other with zinc phosphate cement as a control. After 3 months the teeth were extracted. F profiles in the dentine from the cavity floor to the pulpal surface were determined in tissue immediately adjacent to the restorations. An abrasive micro-sampling technique was used. The F concentration of the dentine was highest immediately beneath glass-ionomer cement filling, decreasing towards the pulpal surface. Overall F concentrations were greater in the dentine beneath the glass-ionomer cement than in that beneath the zinc phosphate cement. It was concluded that the glass-ionomer cement markedly enhanced fluoride uptake by underlying dentine in vivo.

Distribution of fluoride in sound and periodontally diseased human cementum.

Fluoride distribution was investigated by an abrasive micro-sampling technique. The fluoride concentration increased with age in both sound and diseased cementum. In sound teeth, the fluoride profiles (distribution of fluoride from the surface to interior) of the middle and apical cementum were similar. In the diseased cementum the profile of the middle region tended to be more variable than that of the apical cementum, suggesting a possible effect of the oral environment on the fluoride profile at this site.