The method of mouse embryoid body establishment affects structure and developmental gene expression.

To investigate formation of the three primary germ layers in mouse embryoid bodies (EBs), we observed changes in structure and gene expression over a 7-day culture period. We compared these changes using two methods for EB formation: hanging drop (HD) and static suspension culture (SSC). Light microscopy showed that a stratified columnar epithelial layer developed on the surface of EBs formed using the HD method. From Day 3 in culture, ultrastructural changes occurred in the aligned cellular membranes. Condensation of actin filaments was followed by formation of complicated adherent junctions and dilatation of intercellular canaliculi containing well-developed microvilli. These changes were more marked in EBs formed by the HD method than the SSC method. On Day 5 of culture, Brachyury gene expression, a marker for mesoderm formation, was detected only with the HD method. Nestin, an ectoderm marker, and Foxa2, an endoderm marker, were expressed with both methods. These results suggest that in EBs formed with the HD method, actin formation and Brachyury gene expression mark the transition from two to three primary germ layers. Additionally, the HD method promotes more rapid and complete development of mouse EBs than does the SSC method. While the SSC method is simple and easy to use, it needs improvement to form more complete EBs.

Fluorine uptake and crystallinity of dentin treated with glass ionomer cement containing tannin-fluoride preparation.

We investigated the fluorine uptake in various layers of bovine dentin treated with glass ionomer cement (GIC) where a tannin-fluoride preparation (HY agent) was incorporated in the cement powder at ratios of 0% (HY0), 1.5% (HY1.5), 5% (HY5), and 10% (HY10) by weight. The crystallinity of the dentin treated with the HY0 and HY10 cements was also investigated. The higher the ratio of incorporated HY agent, the deeper the penetration of fluorine in the dentin, and the greater the amount of fluorine taken up that bonded with the apatite. Compared with total fluorine uptake, more time is needed for fluorine to form a stable bond with apatite. It is also suggested that the crystallinity of dentin is enhanced when exposed to GIC containing the HY agent.

Obturation of dentinal tubules with tannin-fluoride preparation (HY agent) incorporated into glass ionomer cement.

The degree of obturation of dentinal tubules as well as the dentinal uptake of F, Zn and Sr was investigated after placement of glass ionomer cement (GIC) containing variable proportions of the tannin-fluoride preparation, HY agent, into freshly prepared cavities. It was found that when HY agent was incorporated into the cement powder, there was both increase in electrical resistance in the dentinal floor of the GIC-restored cavity in addition to inhibition of dye penetration. Further, these changes were directly proportional to the concentration of HY agent. Electron probe microanalysis of the principal constituents of HY agent (F, Zn and Sr) revealed that the penetration depth for F and Zn was also directly proportional to the relative amount of incorporated HY agent, whereas Sr could not be detected regardless of HY concentration. Results clearly demonstrated that the higher the concentration of HY agent incorporated into GIC, the greater the degree of dentinal tubular obturation.

Adhesiveness of glass ionomer cement containing tannin-fluoride preparation (HY agent) to dentin--an evaluation of adding various ratios of HY agent and combination with application diammine silver fluoride.

We bonded a glass ionomer cement (GIC) containing various amounts of incorporated tannin-fluoride preparation (HY agent) to bovine dentin and investigated the effect of the ratio of incorporated preparations and the changes in bond strength over time. HY agent was incorporated into the powder at 0% (HY0), 1.5% (HY1.5), 5.0% (HY5), and 10.0% (HY10) by weight. The shear bond strength and percent of the cohesive failure were measured. Similar tests were performed on samples where diammine silver fluoride was applied to the dentin prior to placing the cement. It was found that the bond strength on the first day was increased by incorporating 1.5% of the HY agent in the GIC. The combined use of diammine silver fluoride increased the bond strength of the GIC.

Antiviral Substances with Systemic Effects Produced by Basidiomycetes such as Fomes fomentarius.

Inhibitors of plant virus infection with systemic effects were found in the culture filtrates of Basidiomycetes such as Fomes fomentarius and Schizophyllum commune. These inhibitors were widely distributed in Agaricales and Polyporales. The inhibitors designated as BAS (Basidiomycete Antiviral Substance) were highly active against the mechanical transmission of tobacco mosaic virus (TMV). No toxic effect was observed on the host plants. BAS-F, a polysaccharide produced by F. fomentarius, almost completely inhibited infection, when BAS-F at 2 µg/ml was applied to the same surface of leaves of Xanthi-nc tobacco 24 h before TMV inoculation to the upper surface of the leaves, and 500/0 inhibition was shown when BAS-F at 10 µg/ml was applied to the under surface of leaves. BAS-F also induced systemic resistance to the non-treated leaves when it was applied to only one leaf of the plant. BAS-F also had similar effects against the infection of TMV on bell pepper and tomato plants.

Clinical observations on the development of third molars.

In order to investigate the developmental conditions of third molars in Japanese, we studied the panoramic radiographs taken during dental treatment at the Pediatric Outpatient Section of Osaka Dental University Hospital of 9,111 children (4,646 boys and 4,465 girls) between the ages of 7 years 0 months and 16 years 11 months, in addition to 2,769 panoramic radiographs of students of this university (2,312 men 457 women) kept by the Department of Oral Radiology. The following results were obtained. 1. Calcification of the third molars in both boys and girls began as early as 7 years 6 months in the maxilla and 7 years 0 months in the mandible. The average age for initiation of calcification in the maxilla was 9 years 4 months for boys, and 9 years 2 months for girls, while the ages in the mandible were 9 years 1 month and 8 years 9 months, respectively. 2. The average age for completion of the third molar crowns in the maxilla was 11 years 8 months for boys and 11 years 5 months for girls, while in the mandible it was 12 years 4 months and 12 years 3 months, respectively. 3. At greater than 13 years of age, the tooth germ could be found in boys about 70% of the time in the maxilla and 75% of the time in the mandible, while these figures for girls were 65 and 80%, respectively. 4. All four third molars were present in 52.3% of the males and 45.5% of the females, while 9.5% of the males and 12.0% of the females had no third molars at all. 5. The direction of eruption was classified as either vertical, mesial, horizontal, distal, or buccal/lingual type. The rate for the vertical type in males was 70% in the maxilla and 45% in the mandible, while these figures for females were 50 and 40%, respectively. 6. Microdontia of the third molars appeared only in the maxilla. 7. Congenital absence of the third molars was more common in females than males, and occurred more frequently in the maxilla than in the mandible. The results of this study allow a better understanding of the third molars of Japanese and provide an aid to planning in such areas of clinical pediatric practice as guiding occlusal development.

Dental findings of patients who underwent liver transplantation.

Cyclosporin-induced gingival enlargement was presented. Enlargement was noted at several sites in the mouth of five patients taking Cyclosporin following liver transplantation. Papillary gingival enlargement was observed to affect the entire maxilla and mandible. Enlargement was particularly marked in the interdental papillary region on the labial side of the anterior teeth of the maxilla. Discoloration of the teeth was observed. Radiographic findings were unremarkable. Oral management of these patients is the prevention of dental caries and infection originating in the area of gingival enlargement. It is important to begin proper brushing as early as possible for suppressing progression of gingival enlargement. For prevention of dental caries, prophylaxis is more important in the case of liver transplantation than with normal patients. It should be stressed to the patients or their parents that periodic examination, topical application of fluoride and pit and fissure sealants are of special importance.

Radiographic observations on root resorption in the primary dentition.

In order to construct standardized charts for root resorption in the primary dentition of Japanese children, we investigated the stages of resorption (1/4, 1/2 and 3/4 of the root) based on the criterion of Fanning, et al. using 11,167 panoramic radiographs (5,759 of boys and 5,408 of girls). The following information was obtained. 1) The root resorption for a tooth on one side was the same as for its counterpart on the other side regardless of differences in sex or arch. 2) The average age for each root resorption stage was lower in girls than in boys regardless of differences in sex or arch. 3) The average age for each root resorption stage was lower in the mandible than in the maxilla for every tooth. 4) In the maxilla, the period between 1/4 to 3/4 resorption of the root was greater in the primary molars than in the primary anterior teeth. However, the opposite was true in the mandible. 5) Although no difference was observed between the maxilla and the mandible in the resorption period for the primary incisors and canines, the resorption time for the primary molars was greater in the maxilla than in the mandible. 6) When the relationship was observed between the resorption stages for each tooth and the calcification stages for the corresponding successional permanent tooth. a) With the exception of the maxillary and mandibular canines, the average age for 1/4 resorption of the primary root corresponded to the period between completion of the permanent crown and initial root formation of the successional permanent tooth. b) With the exception of the maxillary and mandibular canines, and the mandibular second premolars, the average age for 3/4 resorption of the primary root corresponded to the period between 1/4 and 1/2 formation of the root of the successional permanent tooth. From these results, standardized charts were constructed for the resorption of the roots of primary teeth in Japanese children. These standardized charts are useful in daily clinical practice in such areas as endodontic treatment of primary teeth and orthodontics.

[Dental treatment under general anesthesia of a patient with pulmonary atresia with intact ventricular septum].

A case of pulmonary atresia with intact ventricular septum in a 4-year-4-month boy, whose dental treatment was performed under general anesthesia, was reported. For the general anesthesia, the medication Digoxin was stopped 24 hours before the treatment. For the prevention of bacterial endocarditis, medication consisting on antibiotics of the penicillin series was administered 24 hours before the treatment. The anesthesia was administered with the modified N.L.A. method with Ketamine and Diazepam. The dental treatment went smoothly, and was finished within 1-hour-15 mins from the start. Anesthesia was administered for 1-hour-45 mins. The prognosis was good, and the patient was discharged the next day. It should be noted that as for performing dental treatment under anesthesia or not using anesthesia, there are some different opinions. We think that it must be discussed from the point of view of the effect of the dental treatment on the patient versus the danger of the anesthesia. In this case, we found that, under general anesthesia, stress of the patient was reduced, and the dental treatment was able to be performed smoothly and safely.

[Oral condition of infantile acute lymphatic leukemia with microbisme substitute].

The oral condition of a 7 year old boy at the 12th and 13th remission induction therapy sessions since contracting acute lymphatic leukemia was investigated clinically and microbiologically. The findings obtained were as follows: 1) The appearance of gingivitis coincided with the decrease of white blood cells 7 to 9 days after administration of the anti-leukopenic drugs. 2) Gingivitis appeared on the same site of the oral cavity at both remission induction therapies sessions. 3) The bleeding from the gingival lesions corresponded to the decrease of blood platelet at both remission induction therapies sessions. Conversely, gingivitis disappeared with the improvement of peripheral blood conditions. 4) The total number of oral bacteria decreased after administration of the antibiotics, although the ratio of Candida in the oral microbial flora increased markedly. 5) Typical symptoms of oral candidiasis were not observed after the appearance of the microbisme substitute.

[A case report on the achondroplasia and its dental findings].

Achondroplasia is characterized by an undergrowth of arms and legs bones, low height and undergrowth of the Basis cranil. The name of this disease was called Chondrodystrohia foetalis before Parrot reported the name of this disease as Achondroplasia, distinguished from other similar diseases. We are reporting in this paper on an 11-year, 2-month-old girl with Achondroplasia. The dental findings as follows: 1) Open bite was observed for the front teeth. 2) The size, number, form and growth of the teeth were usual. 3) The tongue was a little bigger than usual. 4) According to X-ray cephalometric analysis, undergrowth of the Basis cranii and relative anterior cross-bite were visible.

[Fluoride uptake from fluoride releasing resin as an orthodontic adhesive on human enamel].

FluoroBond is one kind of fluoride releasing, visible light-activated bonding system for orthodontic bracket placement. The first aim of this study was to investigate the fluoride release from FluoroBond. The second aim of this study was to determine the fluoride uptake by human enamel which was immersed in distilled water for 30 days in contact with FluoroBond. The third aim of this study was to demonstrate the fluoride uptake by human enamel adjacent to the bracket as well as by the human enamel beneath the bracket which was placed using FluoroBond, and immersed for 30 days in distilled water. The results obtained were as follows. 1) A great amount of fluoride was released from FluoroBond immediately after immersion. The fluoride released weakend rapidly over the first 10 days. However, the fluoride released became stable after the 10th day. 2) The uptake of fluoride from FluoroBond was large both on the surface and the subsurface enamel in contact with it. 3) When FluoroBond was used as a bracket bonding material, fluoride was absorbed from FluoroBond by the enamel not only under the bracket but also adjacent to the bracket.

Effect of water isolation and early finishing on hardness of glass ionomer cements.

Glass ionomer cements have the disadvantage of being vulnerable to moisture. We would like to overcome this problem by clinical procedures. Three glass ionomer cements were tested in vitro with the goal of protecting these materials from moisture during clinical operations. To observe the effectiveness of various surface protective measures, we divided each cement sample into six groups, each of which underwent 24-hour surface treatment. The first group was a control where the cement was covered with a glass slab for 24 hours. The remaining five groups were subjected to no treatment or treatment with varnish, cocoa butter, Teethmate-A, or Ketac-Glaze. Two additional groups were prepared for comparison of early finishing with and without water spray. When the Vickers hardness number (HVN) for each sample was measured at 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, and 40 days, it tended to increase after 24 hours, reaching a maximum value at different times with different cements. Analysis of variance revealed that during the first few days the hardness of the control was significantly different from that without treatment or with treatment by varnish or cocoa butter. However, treatment with Teethmate-A or Ketac-Glaze produced results close to those for the control. Significant differences in hardness during the first few days were noted when early finishing was carried out under wet and dry conditions. These findings indicate that a light-cured unfilled resin should be applied to the surface of glass ionomer cement immediately after the initial set to allow complete setting without interference by oral fluids. Also, water spray should be avoided during contouring of the cements if they have not fully hardened.

[Case report of osteogenesis imperfecta].

Osteogenesis imperfecta (OGI) is a rare genetic disease which, as a result of a disorder in the formation of the organic stroma of the bone due to a defect in osteogenic function, induces brittle bones, whereby only weak forces bring about multiple, repeated pathological fractures. This disease is thought to entail various problems with regards to carrying out pediatric dentistry due to the ease with which bones may be fractured. We report here the findings obtained as a result of the careful examination of a 1-year-3-month-old girl encountered in our practice and who was diagnosed as having osteogenesis imperfecta. 1) Out of the three major symptoms for osteogenesis imperfecta, this case showed signs of fragile bones and blue scleras, but did not reveal signs of deafness. 2) There was retardation in system growth and development. 3) Aside from a high level of alkaline phosphatase, there were no notable abnormalities revealed in the biochemical blood tests. 4) Dentinogenesis imperfecta was observed throughout the erupted teeth. 5) There was a definite improvement in cooperation with each visit to the clinic.

[A staged restoration system for the uncooperative children utilizing glass ionomer cements].

The purpose of this study was to investigate a treatment system intended to promote improvement in the cooperation of patients. The subjects of the investigation were 45 uncooperative patients who had difficulty in accepting regular dental treatment. This treatment system consists of A) caries inhibition stage by Ag(NH3)2F, B) first temporary restoration stage with low viscosity glass ionomer cement, C) second temporary restoration stage with restorative glass ionomer cement and D) final restoration with regular restorative material. One treatment stage in the system was carried out according to the grade of the cooperation of the patients, then the advanced treatment stage superseded the former when the cooperation was improved. The period of time required for the improvement of cooperation, and the durability of the glass ionomer cements were examined. The following results were obtained. 1. The durability of the low viscosity glass ionomer cement was 11 months for the anterior teeth, and 12 months for the posterior teeth. 2. The durability of the regular glass ionomer cement was revealed to be 18 months for the anterior teeth and 17 months for the posterior teeth. 3. 7 months were required for the improvement in the cooperation of the patients from stage B to stage C and 14 months for improvement from stage C to stage D. 4. Improvement in cooperation appeared in a shorter time when this treatment system is begun to be applied to the patients at lower age. The staged restoration system is an effective method for the behavior management of uncooperative patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Application of composite resin inlays to deciduous molars--a clinical observation of the resin onlay].

Although composite resin has been used as an aesthetic restorative material, wear and fracture of the resin of fracture of the tooth structure are likely to occur when the size of the dental cavities are large. In addition to the lack of the aesthetic value, clinical results of prefabricated metal crown revealed several problems which were caused by the wear of the metal and the ill-adaptation of the cervical margin. In the present study, 50 devitalized deciduous molars were treated with composite resin onlays which were designed to cover the entire occlusal surface of the deciduous molar, and the clinical results were evaluated for a 6 month period. Additionally, for the purpose of simplification of the laboratory process for making resin onlays, ready-made occlusal shells were fabricated. The variety of the prepared shell size consisted of 7 sizes for the first deciduous molar, 9 sizes for the upper second deciduous molar and 10 sizes for the lower deciduous molar. The following results were obtained. 1) A partial resin fracture at the peripheral area of the mesio-buccal cuspid was found in five cases out of 50. 2) A glossy appearance on the surface of the onlay which was created by coated unfilled resin disappeared after 6 months of observation. 3) In relation to the resin onlay, when the antagonistic tooth was restored with prefabricated metal crowns, holes were made by attrition on all the crowns within a 3-4 month period.(ABSTRACT TRUNCATED AT 250 WORDS)

[SEM observation for composite resin filler].

The nature and the type of fillers in composite resin are multifarious. The purpose of this study is to determine the methods of distinguishing the fillers. After the treatments stated below, the surface of polymerized composite resins was observed by means of SEM. 1) The air-inhibited layer on the surface of composite resins was removed by acetone. Observations showed inorganic filler and prepolymerized filler protrusions on the resin surface; submicron filler and microfiller were noticeable. 2) Following the treatment in #1, composite resins were soaked in fluoric acid in order to dissolve any inorganic filler substance. Results displayed pores in the area of the dissolved inorganic filler while a microporous surface was observed on the prepolymerized filler. By this process the type of prepolymerized filler can be classified according to the forms of the contained inorganic filler. 3) The surface of the composite resin was polished with #1200 sand paper. This method shows the difference between the fillers and the matrix resin; however, a clear distinction of the type of filler is difficult to determine. 4) After treatment in #3, the specimen was soaked in fluoric acid. Similar results as treatment in #2 were found; however, microstructure of the syntered filler was easily observed. It is possible to distinguish the filler types of the composite resins by the above mentioned treatments.

[Effects of fluoride releasing resin on the denture base on bovine enamel].

The first aim of this study was to investigate the amount of fluoride released from fluoride releasing resin for the denture base (F-resin). The second aim of this study was to determine the uptake of fluoride with bovine enamel, which was immersed in distilled water for 90 days in contact with F-resin. The results obtained were as follows: 1) The amount of fluoride released from F-resin decreased gradually. From the 10th day of immersion, the amount of fluoride released was almost constant. The fluoride could be detected on the 90th day. 2) The uptake of fluoride from F-resin was great both on the surface and the subsurface enamel. 3) The uptake of fluoride from F-resin was almost proportional to the immersing time.

Morphological characteristics of the teeth of Newar children.

The morphology of the teeth of Newar children was investigated in order to determine racial characteristics of the teeth in comparison with those of Japanese. The results were as follows. 1) The incidence of a C type labial surface pattern on the maxillary incisors was greater in Newars than Japanese for both the maxillary central and lateral incisors. 2) The total incidence of shovel-shaped and semi-shovel-shaped maxillary incisors was greater than 80% in Japanese, although at most about 25% in Newars. 3) The incidence of interstitial tubercles on the maxillary premolars in Newars was less than in Japanese. 4) The incidence of the cusp of Carabelli on maxillary first molars was greater in Newars than in Japanese. 5) Although the incidence of protostylids on the mandibular first molars was less in Newars than in Japanese, the incidence of the + type occlusal groove pattern was higher in Newars. Even though four-cusp mandibular first molars were more common in Newars than in Japanese, the incidence of a sixth cusp was lower in Newars. Also, the incidence of a sixth cusp was lower in Newars. Also, the incidence of medial of medial lingual accessory tubercles was slightly higher in Newars than in Japanese. Examination of the Newar teeth confirmed previous findings that they are racially Caucasoid, although they have some similarities with Japanese.

Calcification of the permanent first molars observed in panoramic radiographs.

We investigated the development (calcification) stages of the permanent first molars of Japanese children by classifying them into 14 stages by the criterion of Moorrees, et al., using 11,167 panoramic radiographs, 5,759 of boys and 5,408 of girls, between the ages of 2 years 0 months and 14 years 11 months. The following information was obtained from calculations of the average chronological ages for the development stages of these teeth. 1) The development of first molars was earlier in girls than boys. This was particularly true during the middle phase of development. 2) A first molar on one side developed at the same rate as its counterpart on the other side, regardless of differences in sex or arch. 3) In both boys and girls, the development of the mandibular first molars was about one month earlier than that of the maxillary first molars at each stage. 4) When these results were compared with those of Nolla, Moorrees and Haavikko, who pioneered this field of study, it was clear that the development of the teeth in Japanese is different from that in Caucasians. 5) We made charts of the development of the first molars in Japanese which can be applied in routine clinical practice.