Diet and risk of colon cancer in a large prospective study of older women: an analysis stratified on family history (Iowa, United States)

The aim of this study was to determine if diffusible angiogenic growth factors were released in human dental pulp during orthodontic tooth movement. These factors, if diffusible, could induce angiogenesis in other tissues, and may then be isolated and identified. The pulps from 14 premolar teeth treated with straight wire fixed orthodontic appliances for 2 weeks were compared with those of 14 untreated control premolar teeth from the same subjects. Following tooth extraction and sectioning, 1-mm horizontal sections of pulp tissue were embedded in collagen with 1-mm sections of rat aorta and co-cultured in growth media for up to 4 weeks. Sections of rat aorta alone were also cultured. Angiogenic changes in the form of microvessel growth were observed by light microscopy. Microvessel identification was confirmed by electron microscopy and by immunohistochemistry using staining for factor VIII-related antigen marker for endothelial cells. When compared at days 5, 10, and 14 of co-culture, the number of microvessels was significantly greater in the pulps from orthodontically moved teeth than in those from the control teeth. The number of rat aorta microvessels was also significantly greater when co-cultured with pulp from orthodontically moved teeth than with pulp from control teeth and when compared with control cultures of rat aorta alone. There were no significant differences in microvessel numbers between the rat aorta co-cultured with pulp from control teeth and control cultures of rat aorta alone. These results indicate an increase in angiogenic growth factors in the pulp of orthodontically moved teeth, and the enhanced response of the rat aorta when co-cultured with this pulp shows that these factors appear to be diffusible.     

Abortion and family-binding models: fertility limitation in Hungary

The fetal circulation of normal rat placenta was studied by parallel examination with the scanning electron microscope (SEM) and the transmission electron microscope (TEM). By examining casts of vessels injected with latex and prepared by corrosion in hypochlorite solutions, the fetal arteries, veins, and capillaries of the placenta could be traced in the scanning electron microscope and, in addition, the ultrastructural details of microcirculation and luminal surfaces could be studied. Cast specimens showed fetal arteries entering the center of the placenta and branching into long, thin vessels which traversed almost the entire thickness of the placenta before dividing into a markedly tortuous capillary network. The smooth-surfaced capillary vessels located at the arteriolar end flowed into a much less tortuous prevenous capillary network which conducted the blood into collecting venules and veins. Placental blood vessels examined by the TEM provided evidence that details observed by the SEM were accurate for the ultrastructural appearance of fetal arteries, capillaries, and veins.     

Root canal morphology of maxillary permanent first molar teeth at various ages

The root canal anatomy and pulp chamber morphology of 216 maxillary permanent first molar teeth of known age was examined using a radiographic technique after infusion of the root canal system with a radiopaque sodium iothalomate gel. This technique proved to be a rapid and effective method for the examination of root canal morphology and is recommended when root canal anatomy needs to be examined before further investigations are carried out. Over 95% of palatal and disto-buccal roots contained a single root canal. The mesio-buccal root was more complex. All types of configurations were seen. Only 26% of mesio-buccal roots showed a single canal. The pulp canal in all roots appeared to narrow at an early age. In the mesio-buccal root, a definite two-directional calcification pattern was apparent in most teeth by the age of 10. The rate of progress of root formation was very variable. There was no apparent relationship between the type of canal system in the mesio-buccal root and the type of canal orifice present. The transverse cross-sectional shape of the pulp chamber was trapezoidal in 81% of teeth.     

Fluoride distribution in dentine and cementum in human permanent teeth with vital and non-vital pulps

Twenty-two selected permanent teeth [11 with vital pulps and 11 with non-vital (necrotic) pulps] were obtained from patients aged from 20 to 73 yr in Nagoya, Japan. Fluoride (F) profiles in tooth samples were examined by using an abrasive micro-sampling technique. F levels in the pulpal dentine were significantly higher in vital than non-vital teeth for each age group, although there were observed increases of F with age. In the cementum the F levels were strongly related to age and there were few differences in profiles and levels of F between vital and non-vital teeth. It was concluded that vital pulp is an important factor for the pulpal dentine to absorb fluoride.     

Biocompatibility of Optibond and XR-Bond adhesive systems in nonhuman primate teeth

This study evaluated the histologic responses of two different adhesive systems on the teeth of seven healthy adult monkeys. Class V cavities in 128 teeth were observed at 7,21 to 27, and 90 to 97 days. Statistical data showed no significant differences in pulp inflammation between the Optibond (Kerr), XR-Bond (Kerr), and IRM (Caulk) groups in pulps at the three time intervals. Some odontoblastic disruption and inflammation was seen in pulps restored with XR-Primer at the three time intervals. Pulp healing was similar in teeth treated with both direct-capped Optibond and calcium hydroxide, and there was no significant increase in pulpal inflammation with time. No abscesses or necrotic pulps were seen in any teeth. Optibond and XR-Bond adhesive systems are biologically acceptable in nonhuman primate pulp tissues.     

Immunohistochemical localization of endothelin-1 in placenta and fetal membranes in term and preterm human pregnancy

A case is reported in which an intruded incisor was initially treated by an endodontic dressing with calcium hydroxide and then extruded using a removable orthodontic appliance. A follow-up examination seven years after completion of endodontic therapy and bleaching showed a favourable response. A review of the relevant literature indicates that intrusion occurs in five to twelve per cent of luxation cases. In this type of injury maximum damage occurs to the pulp and all supporting structures because the tooth is driven into the alveolar process. Complications which have been reported include: pulp necrosis, apical radiolucencies, partial or total pulp calcification, root resorption (surface, inflammatory or replacement), marginal periodontal bone breakdown, and arrested or disturbed root development. The prognosis for pulp survival after intrusion is much more favourable for teeth with incomplete root formation than for teeth with complete root formation. Treatment options available to bring an intruded tooth into alignment are: to await spontaneous re-eruption which may occur if root formation is incomplete, uncovering of the intruded crown, orthodontic extrusion which is allied with gentle luxation if the tooth does not move, and immediate surgical repositioning.     

Development of neural elements in apical portions of cat primary and permanent incisor pulps

Pulp development was studied with light and electron microscopy in apical portions of cat primary and permanent incisors at various stages of development in order to qualitatively assess hypothesized differences during maturation. Primary and permanent tooth pulps passed through similar stages up to when the primary teeth began to resorb. At that point permanent tooth pulps continued to develop in complexity relative to myelinated axons and developed thin epineurial sheaths. Although the stages were similar in several regards, the time needed by the permanent tooth pulps to reach each stage was considerably greater than for the primary tooth pulps. It is of interest that the young permanent teeth had only a small portion of their final complement of nerves in spite of their relatively complete development. Individual axons, especially myelinated axons, appeared more immature in younger primary and permanent teeth. This suggests a less mature sensory capability for erupting primary teeth as compared to fully developed primary teeth as well as for erupting and young permanent teeth compared to old permanent teeth.     

纳米尺度析出相透射电镜的统计分析技术探讨

纳米级析出相在钢中起到析出强化作用或者作为晶粒生长的抑制剂，来获得特定取向的织构，因此，对析出相进行系统分析非常重要。目前通过扫描电镜和透射电镜很难实现纳米尺度尤其是50 nm以下析出相的统计分析工作。实验通过将扫描电镜夹杂物统计的Feature软件包应用到透射电镜的能谱控制软件中，从而实现了透射电镜直接对钢中纳米尺度析出相的统计。同时对透射电镜进行析出相统计中的主要影响因素如样品制备方法、采集参数、分类方法和大面积统计方法等进行了深入研究。结果表明，实验最佳条件为采用新的复型方法制样，能谱单点采集时间为5 s,图像分辨率为2 048,连续采图统计，终止条件为析出相统计数量过100个，确定了析出相制定分类规则的具体实现方法。结合无取相电工钢W800和WH470的实验统计结果可知，其析出相种类有CuS₂和MnS+CuS₂的核壳复合析出，且实验方法能够统计分析的析出相最小尺寸为10 nm。     

Anatomical variations in the dentition of the domestic cat

Skulls (n = 155) of adult domestic cats were examined macroscopically and anatomical variations were documented. The maxillary second premolar tooth was absent in 7.9% of cases, and was found to have a single root in 27.7%, partly fused roots in 55.1% and two fully formed roots in 9.2% of cases. The maxillary first molar tooth was absent in 2.3% of cases; a single root was present in 35.0%, a partly fused root in 34.7%, and two roots in 28.0% of cases. Supernumerary roots were found on the maxillary third premolar teeth in 10.3% of cases. Other variations were found to be extremely rare.     

Effect of mechanical removal of the pulp upon the retention of odontoblasts around the pulp chamber of human third molars

The pulp chambers of 11 freshly extracted human third molars were exposed by cutting off the roots apical to the cervical margin and the pulps were either removed with forceps and discarded or left in situ. The teeth were fixed, demineralized, divided longitudinally, embedded in resin and 2-micron sections stained with toluidine blue were examined by light microscopy. In pulp-removed specimens the percentage retention of the odontoblast layer with the predentine varied near the longitudinal division but when sectioned deeper all six specimens displayed 100% retention. The intactness of the retained odontoblast layer was mostly good as judged by the mutual close apposition of the distal ends of the cell bodies and their relation to the predentine. The retention of the odontoblast layer with the predentine may be due to the distribution of fibronectin, which others have shown is present between odontoblasts, and between odontoblasts and predentine, but lacking beneath the odontoblast layer.     

Root resorptions in upper first premolars after application of continuous intrusive forces. Intra-individual study

A scanning electron microscopy study of possible root resorptions and their localization after application of continuous forces of different magnitudes was conducted. Twelve upper first premolars, indicated for extraction, were previously intruded with constant forces. The teeth were divided into 3 groups: 1. non-moved control teeth, 2. continuous force application of 50 cN for 4 weeks, 3. continuous force application of 100 cN for 4 weeks. Specially designed NiTi-SE-stainless steel springs were utilized to exert the actual forces. After experimental tooth movement, the extracted teeth were dehydrated, metal-coated and examined by scanning electron microscopy. The intruded teeth showed resorptive areas consisting of lacunae (concavities) in the mineralized root surface. The teeth moved with 50 cN showed in the apical third several, in the medial third few, and in the cervical third no resorptive areas. In the case of the teeth moved with 100 cN, we observed resorptive areas in most of the apical third--including the apex contour-, several in the medial third, and none in the cervical third. In the control group no resorptions were observed. Thus, our results suggest that intrusion of human teeth with continuous forces induces root resorption, depending on the magnitude of force applied.     

粉末热等静压9.75％钒成分冷作模具钢组织与力学性能的研究

通过气雾化制粉-热等静压工艺成功制备了含钒9.75％冷作模具钢.借助X射线衍射仪、扫描电镜、电子能谱分析仪、透射电镜等研究了该成分钢种不同热处理状态的相组成、组织形貌.研究表明:退火态相组成为铁素体和MC型碳化物及少量M7C3型碳化物,碳化物呈近球形颗粒状、粒径大多在2μm以下,分布均匀;1 120℃真空淬火条件下,随...     

New horizons for therapy based on the boron neutron capture reaction

Experimental studies were undertaken in immature rat molar teeth to investigate the relationship between root development and the prognosis after partial extrusion. The experimental partial extrusion was induced at 1/2 root formation, 2/3 root formation and 3/4 root formation, using an extrusion device designed by the author. Histopathological studies and SEM observation of the pulpal tissue in rat maxillary first molars with partially formed roots after partial extrusion were conducted and evaluated. The degree of extrusion was changed according to the development of the root to produce a similar luxated state. The rats were sacrificed immediately after experimental extrusion, immediately after operation, and after 3 days, 7 days, 14 days, 30 days, and 60 days to compare the histopathological and SEM findings between experimental groups and control groups. Immediately after the extrusive injury, ablations of the odontoblast layer from dentin were seen with retention of a fluid component in the ablated spaces in the pulp. On 1 and 3 days after surgery, cellular components such as erythrocytes and leukocytes due to bleeding were seen. Ablations of the odontoblast layer were seen in the coronal pulp most frequently in the pulp horn, cervical area and floor of the pulp chamber. In general, pulp reaction after extrusion in groups with more complete root formation was more severe than in groups with less complete root formation. It is suggested that the more complete the root formation, the greater the effect on the pulp as result of partial extrusion, while with less complete root formation, the greater the malformation of the root apices.     

Incremental lines in root cementum of human teeth: an approach to their ultrastructural nature by microscopy

In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-micron thickness were no longer visible in semi-thin sections (thickness, 1-2 microns) of the same specimen in the same area. The assumption that annulations could be caused by super-imposing structures in the depth of field of the light microscope's objective lens was not verified by CLSM. Fiber bundles of higher density than the surrounding matrix in TEM micrographs could not be connected unambiguously with annulations in LM micrographs. After all, the ultrastructural nature of cemental annulations remains an open question.     

Pulpal response to a resin-modified glass-ionomer material on nonexposed and exposed monkey pulps

OBJECTIVE: This study evaluated the biocompatibility of a resin-modified glass-ionomer material on monkey pulps. METHOD AND MATERIALS: Standardized Class V cavities were prepared in 112 teeth distributed in six healthy adult monkeys. The resin-modified glass-ionomer cement was placed in 24 nonexposed and 36 exposed pulps according to manufacturer's instructions. ZOE was used as a control in nonexposed pulps, while calcium hydroxide was used as a control for exposed pulps. Tissues were collected at 6 to 7, 21 to 27, and 90 to 97 days. After demineralization, the teeth were serially sectioned, stained, and observed by light microscopy. RESULTS: Except for one resin-modified glass-ionomer pulp at 6 days, there were no differences between the responses of nonexposed pulps to resin-modified glass-ionomer specimens and ZOE controls. In exposed pulps, eight of 36 resin-modified glass-ionomer pulps showed various grades of inflammatory response, all associated with stained bacteria. Pulpal healing was similar in both resin-modified glass-ionomer and calcium hydroxide direct-capped exposures. Twenty-two of 26 exposed pulps restored with the resin-modified glass-ionomer cement showed dentin bridge formation at 21 and 97 days. CONCLUSION: The resin-modified glass-ionomer material exhibited acceptable biologic compatibility in exposed and nonexposed cavities.     

Quantitative contribution of the collagen network in dentin hybridization

PURPOSE: To determine the quantitative contribution of dentin hybridization to bonded assembly strength and demonstrate the micromorphology of the interface with and without collagen present. MATERIALS AND METHODS: Four groups of 10 molar teeth were finished to a 320 grit dentin smear layer. Two groups served as controls and two experimental groups were subjected to collagenase digestion of the collagen exposed by acid conditioning. All-Bond 2 and Amalgambond were used to bond Bisfil and Epic resin composite, respectively. Stored in water at 37 degrees C for 24 hours the assemblies were tested in a shear mode at a crosshead speed of 5 mm/minute. Means and standard deviations were subjected to analysis for statistical significance. Twenty four teeth in four groups were examined by scanning (SEM) and transmission electron microscopy (TEM) for the relationship between resin and conditioned dentin with and without the collagen network. RESULTS: All-Bond 2 and Amalgambond controls were 28.41 +/- 3.9 and 19.04 +/- 5.96 MPa, collagenase-treated groups scored 26.43 +/- 2.90 and 19.70 +/- 4.25 MPa respectively. No significant difference existed between the control and experimental groups. SEM showed an intertubular collagen network with patent tubules and a pronounced porous, irregular dentin topography following collagen digestion. A distinct hybrid zone and tubular penetration was observed but the collagenase-treated specimens showed only resin in the tubules and their lateral extensions. TEM confirmed the absence of a distinct hybrid zone in the collagenase groups with a tight, gap-free junction between the resin and the undemineralized dentin. An electron dense zone (< 50 nm) at the leading edge of conditioning was observed for All-Bond 2 and Amalgambond groups. It was concluded that the resin-reinforced or hybridized, collagenous network does not detract from, nor contribute any significant quantitative value per se to dentin bonding with the systems tested.     

Scanning electron microscopic evaluation of different endodontic procedures on dentin morphology of human teeth

Four manual endodontic instruments, an ultrasonic and an endosonic system were studied with a view to evaluating the morphology of the smear layer and the amount of debris and pulpal residues in the apical third of human extracted straight teeth from 55- to 75-yr-old patients. The manual instruments were K files, Ergoflex files used with the step-back technique, Canal Master with its own technique, and Flex-R with the Roane technique. The ultrasonic system was Suprasson Piezo and the endosonic was Excalibur. Human extracted teeth with straight canals were used and examined under a scanning electron microscope. All manual instrumentations showed a homogeneous compact smear layer and no pulp residues. No statistical differences were observed among the four manual techniques. Ultrasonic technique showed the complete removal of the smear layer, leaving small amounts of pulp debris at the apical third, while the Excalibur showed an almost complete elimination of the smear layer, leaving a homogeneous layer of pulpal residues along the canal.     

Cholesterol 7 alpha-hydroxylase activity in hypothyroidism and hyperthyroidism in humans

The effects of three root-end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere. The materials compared were a light-cured glass ionomer cement (Vitrebond), a reinforced zinc oxide-eugenol cement (Kalzinol) and amalgam. The root canals of 27 two-rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions. The roots were apicected and root-end cavities filled with the tested filling materials. The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots). Radiographs were taken of each jaw section and subjected to image analysis. Healing was evaluated based on measurements of the size of the periradicular radiolucent areas. ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials. These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported. The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.     

Subtle neurological deficits and psychopathological findings in substance-abusing homeless and non-homeless veterans

PROBLEM: In vitro studies have demonstrated microfractures in resected roots after root end cavity preparation with ultrasonic tips. Such microfractures are of concern; however, they may be artifacts. OBJECTIVES: To assess the incidence of microfractures after ultrasonic root end cavity preparation in situ. STUDY DESIGN: Fifty-two roots in two cadavers were endodontically treated, the soft tissues excised, and the root ends exposed and resected. The resected root surfaces were replicated with polyvinylsiloxane impressions. Root end cavities were prepared with ultrasonic tips, then impressed a second time. The roots were retrieved; 25 were processed for direct SEM examination as were both the impressions of each root. The specimens were examined by stereomicroscope and scanning electron microscope. RESULTS: In the impressions, the resected and prepared surfaces appeared irregular, but none demonstrated microfractures. In contrast, 15 retrieved roots showed microfractures. CONCLUSIONS: Ultrasonic root end cavity preparation in situ did not cause root microfractures, and the impression technique could be clinically usable with minor modifications.     

Effects of TMCP Schedule on Precipitation,Microstructure and Properties of Ti-microalloyed High Strength Steel

Using the similar compositions of the Ti-microalloyed high-strength steels produced by the thin-slab casting process of compact strip production(CSP),four thermo-mechanical control processes(TMCP)after the simulated thickslab casting,i.e.the two hot rolling routes and the two cooling processes,were designed,aiming at achieving the same mechanical properties as the thin strip products.The final microstructures after the four TMCP processes were examined by optical microscope(OM),scanning electron microscope(SEM)and transmission electron microscope(TEM).The tensile properties and Charpy impact energy were measured correspondingly.Strain-induced TiC precipitation was found in the two-stage rolling route with the finish rolling temperature at low levels,leading to grain refinement due to the pinning effect during austenite recrystallization.Precipitation hardening in ferrite was observed when a period of isothermal holding was applied after hot rolling.It could be concluded that both finish rolling temperature and the subsequent isothermal holding temperature were crucial for the achieved strength level due to the combined effect of grain refinement and precipitation hardening.At the same time,it was found that the isothermal holding led to poor impact toughness because of remarkable precipitation hardening.Therefore,it was suggested that the precipitation kinetics of titanium carbides in both austenite and ferrite should be investigated in future.