No abstract available.
Animals ; Corrosion Casting* ; Corrosion* ; Head* ; Rats*

The internal morphology of the right and left atria of rabbit, cat, pig, and human, particularly on the luminal structures of the auricle, were observed by stereomicroscope improving corrosion casting method using latex. Structures of the right auricular casts markedly differ from those of the left side, consisting of defined surface sturctures with distinct folds and branching patterns. The main atrial region consists of smooth surfaced single mass of the latex, and the auricular region is characterized by well developed branching patte and delicate small folds. The results of this study indicate that auricula have well organized duct-like luminal structures and many small pouches (out-pocketings) expanding the internal wall of the duct-like structures and small pouches. The endocardial nuclear imprints on the surface of the folds in the auricular region appeared larger and deeper than those on the atrium proper region of the atrial cast. These morphological observation will be aid in understanding structures of auricular lumen, regional differences of the endocardium and their function to the secretory process of atrial natriuretic peptide (ANP) release.
Animals* ; Cats ; Corrosion Casting* ; Corrosion* ; Endocardium ; Humans ; Latex ; Methods* ; Phenobarbital* ; Secretory Pathway

OBJECTIVEThe purpose of this study was to investigate effects of cryotreat on the corrosion resistance of SDA-II medium melting-point castable alloy.

METHODS12 samples were divided into three groups, including the control group, the cryotreated group and the cryotreated & post-cryogenic treated group. The cryotreating process was firstly dropping the temperature from room temperature to -170 degrees C with dropping rate 3 degrees C/min, maintaining -170 degrees C for 2 hrs, and then returning to ambient temperature with an increasing rate of 1 degree C/min. The post-cryogenic process was maintaining the samples in 300 degrees C for 1 hr. Finally, all samples were subjected to the electrochemical potentiodynamic polarization after immersed in the artificial saliva (ISO/TR 10271: 1993 (E), pH 6.8) for 24 hrs at ambient temperature. The exposing area of each sample was 10 mm x 10 mm. The electrochemical tests were carried out in the artificial saliva under 37 degrees C, with the scanning rate of 20 mV/min, starting potential -200 mV below OCP and stopping current 10(-3) A. The corrosion currents (Icorr), the pitting corrosion potentials (Eb) and the potentiodynamic polarization curves were observed using the 283 electrochemical corrosion measuring system automatically.

RESULTSFor SDA-II medium melting-point castable alloy, cryotreat reduced corrosion rate of the alloy, but had no effect on the pitting corrosion potential. As far as the post-cryogenic treatment, it didn't affect the corrosion resistance.

CONCLUSIONThe results suggested that cryotreat was an effective procedure in enhancing the corrosion resistance of SDA-II medium melting-point castable alloy, and it may be applicable in prosthetic dentistry.

Cold Temperature ; Corrosion ; Dental Alloys ; Dental Casting Technique ; Hardness ; Humans ; Materials Testing ; Mechanics ; Saliva, Artificial ; Temperature

To investigate the application and effectiveness of vascular corrosion technique in preparing fetal cardiovascular cast models, 10 normal fetal heart specimens with other congenital disease (control group) and 18 specimens with severe congenital heart disease (case group) from induced abortions were enrolled in this study from March 2013 to June 2015 in our hospital. Cast models were prepared by injecting casting material into vascular lumen to demonstrate real geometries of fetal cardiovascular system. Casting effectiveness was analyzed in terms of local anatomic structures and different anatomical levels (including overall level, atrioventricular and great vascular system, left-sided and right-sided heart), as well as different trimesters of pregnancy. In our study, all specimens were successfully casted. Casting effectiveness analysis of local anatomic structures showed a mean score from 1.90±1.45 to 3.60±0.52, without significant differences between case and control groups in most local anatomic structures except left ventricle, which had a higher score in control group (P=0.027). Inter-group comparison of casting effectiveness in different anatomical levels showed no significant differences between the two groups. Intra-group comparison also revealed undifferentiated casting effectiveness between atrioventricular and great vascular system, or left-sided and right-sided heart in corresponding group. Third-trimester group had a significantly higher perfusion score in great vascular system than second-trimester group (P=0.046), while the other anatomical levels displayed no such difference. Vascular corrosion technique can be successfully used in fabrication of fetal cardiovascular cast model. It is also a reliable method to demonstrate three-dimensional anatomy of severe congenital heart disease and normal heart in fetus.
Corrosion Casting ; methods ; Fetal Heart ; pathology ; Heart Defects, Congenital ; pathology ; Humans ; Models, Anatomic

This study was undertaken to investigate the three dimensional vascular changes of periodontal ligament following orthodontic tooth movement. Experimental tooth movement was carried out in 96 Sprague-Dawley rats with the weight of 250g. They were divided into four experimental groups (each 24 rats). The left maxillary first molar was moved mesially with 25g force in group I, and with 75g force in group II. Each three animals were sacrificed after 1, 6, 12, 24 hours, and 3, 7, 14, 21 days. In group III, 25g mesial force was applied for 3 days, and in group IV, 75g mesial force was applied for 3 days. Then the appliances were removed, and each three animals were sacrificed after 1, 6, 12, 24 hours, and 3, 7, 14, 21 days from removal of appliance. The contralateral molars were used for control group. Casting media was injected via left ventricle and polymerized in warm water. After corrosion of surrounding soft tissue, three dimensional vascular changes were examined using scanning electron microscopy. The findings of this study were as follows: 1. Pressure side of group I and II showed degenerative vascular changes such as vascular compression, reduction of vasculature, leakage of casting media. But, regenerative changes were dominant after 7 days of tooth movement. Although the degenerative vascular changes were more severe in group II, which was exposed to heavy force, the timing of these changes was not different between two groups. 2. Periodontal vasculature was reestablished by the growth of new capillaries and their differentiation and union from the remaining periodontal vessels and vessels of alveolar bone marrow. Although vascular regeneration was more rapid in group I, which was exposed to light force, the vasculature was not fully normalized in both groups even after 21 days. 3. There was no remarkable changes in tension side of group I and II, but looping of capillary, new capillary growth, dilation of vessels, redirection of vessels in the direction of tensile force were occurred. 4. In pressure side of group III and IV, in which appliance was removed after 3 days of orthodontic force, bone resorption was continued even after removal of appliance. Regeneration of vasculature was initiated after 1-6 hours, and it was more rapid in group III than group IV. In both groups, the vasculature was not fully normalized even after 21 days. 5. After removal of appliance, tension side of group III and IV showed vascular compression and loss of vasculature.
Animals ; Bone Marrow ; Bone Resorption ; Capillaries ; Corrosion Casting* ; Corrosion* ; Heart Ventricles ; Microscopy, Electron, Scanning ; Molar* ; Periodontal Ligament* ; Polymers ; Rats* ; Rats, Sprague-Dawley ; Regeneration ; Tooth Movement* ; Tooth* ; Water

We have used selective casting methods to separate pulmonary elastin from vascular elastin in the lungs of rabbits, dogs and pigs. The lungs are digested with 0.1 N NaOH at 75 degrees C for 24 approximately 48 hours with frequent turning as the lungs are filled with air to about 80% of the vital capacity prior to the casting which is done at pressure of 20 approximately 50 mmHg. After vascular injections, we saw many small globular bits of casting material well separated from cast vessels and lying in the pulmonary elastin. Surface forces should make the casting material creep along the vessels even if they are not completely filled, so that the spherical shape is the one expected if the case is extruded into the parenchymal space and the air space. We conclude that this suggests that the pulmonary circulation is partially and temporarily 'open' as seen in the spleen and some other organs, rather than a completely 'closed' one as is generally accepted. At least some of these extravasations may be associated with lymphatics, although we have not proved this.
Animal ; Blood Vessels/ultrastructure ; *Capillary Permeability ; Corrosion Casting ; Dogs ; Male ; Microscopy, Electron, Scanning ; *Pulmonary Circulation ; Support, Non-U.S. Gov't ; Swine

Using ocularluminal methylmethacrylate corrosion casting, we obsesved three-dimentional anterior uveal microcirculation of the rabbit eyes with scanning electron microscope. The two terminal branches of each long posterior ciliary artery turn opposite direction within the iris to run concentric to the pupil; the superior and inferior branches forming the major iridic circle (MIC). Radial branches run both proximally and distally from the MIC, the former distributing to the ciliary process, choroid and ciliary body and the latter distributing to the iris. Venous drainage of the anterior uvea is taken care of by the large iridociliary veins and by marginal capillaries of the process. Each of these drains to the large vessel layer of the choroid and subsquently to the vortex vein.
Capillaries ; Choroid ; Ciliary Arteries ; Ciliary Body ; Corrosion Casting ; Drainage ; Iris ; Methylmethacrylate ; Microcirculation ; Microscopy, Electron, Scanning* ; Pupil ; Uvea ; Veins

Using ocularluminal methylmethacrylate corrosion casting, we obsesved three-dimentional anterior uveal microcirculation of the rabbit eyes with scanning electron microscope. The two terminal branches of each long posterior ciliary artery turn opposite direction within the iris to run concentric to the pupil; the superior and inferior branches forming the major iridic circle (MIC). Radial branches run both proximally and distally from the MIC, the former distributing to the ciliary process, choroid and ciliary body and the latter distributing to the iris. Venous drainage of the anterior uvea is taken care of by the large iridociliary veins and by marginal capillaries of the process. Each of these drains to the large vessel layer of the choroid and subsquently to the vortex vein.
Capillaries ; Choroid ; Ciliary Arteries ; Ciliary Body ; Corrosion Casting ; Drainage ; Iris ; Methylmethacrylate ; Microcirculation ; Microscopy, Electron, Scanning* ; Pupil ; Uvea ; Veins

PURPOSE: Distraction osteogenesis is now a standard method for bone lengthening. However, little is known about the exact mechanism of new bone formation. This study was undertaken to investigate the temporal and spatial changes of angiogenesis during the periods of distraction osteogenesis; the three-dimensional microarchitecture of newly formed vessels and their origin; and the role of angiogenesis with reference to mineralization. MATERIALS AND METHODS: Sprague-Dawley rat's tibia was osteotomized subperiosteally and was distracted at a rate of 0.5 mm per day for two weeks after one week of latency period. Vascular corrosion casting using Mercox was done on the hindlimbs before osteotomy, and at the 1st, 2nd, 3rd, 4th, and 6th weeks postoperatively. Replicated microvascular structures and their distribution patterns at the distraction site and adjacent parent bone were observed temporally and spatially under scanning electron microscope. These findings were compared with radiographical and histological observations. RESULTS: 1. At postoperative first week and second week, proliferation of periosteal vessels were more pronounced than that of endosteal vessels, which corresponded to the early new bone formation in subperiosteal area on histologic sections. 2. At postoperative third week, arterial branches from the medulla of parent bone entered into the distraction gap. Multiple longitudinal vascular branches sprouted out from the newly formed vascular network, and ran towards the interzone. 3. At postoperative fourth week, there was vascular proliferation in the periosteal side of interzone, from which branches arose towards the parent bone. 4. At postoperative sixth week, vascular networks of both sides connected to each other, and few angiogenetic findings were observed. CONCLUSIONS: In distraction osteogenesis, angiogenesis occurred actively during the distraction period and then gradually decreased with time. Taken together with radiographical and histological findings, close temporal and spatial relationship between the angiogenesis and new bone formation at the distraction site was revealed.
Animals ; Bone Lengthening ; Corrosion Casting ; Hindlimb ; Humans ; Latency Period (Psychology) ; Osteogenesis ; Osteogenesis, Distraction* ; Osteotomy ; Parents ; Rats, Sprague-Dawley ; Tibia

OBJECTIVE: To determine the effect of porcelain firing cycle on microstructure of 4 metal ceramic alloys, and to analyze the changes of their corrosion resistance in the artificial saliva. METHODS: We simulated the process of firing and repolishing when fabricating porcelain-fused-to-metal restoration in clinic,and then observed the microstructures of Ni-Cr, Ni-Cr-Ti, Co-Cr alloys and high gold alloy by field emission scanning electron microscopy and energy dispersive spectroscopy. The electrochemical corrosion behavior of alloys in artificial saliva was analyzed by polarization curves and corrview 2 corrosion analysis software. The data of self-corrosion potential and transpassive potential were obtained and analyzed. RESULTS: After the porcelain firing cycle, the surface composition changed slightly, and the morphological in the 3 predominate base metal alloys also changed. The self-corrosion potential turned to more negative, and the transpassive potential declined. CONCLUSION The procedure of porcelain firing cycle can affect the surface microstructure and increase the corrosion of 4 metal-ceramic alloys.
Corrosion ; Dental Casting Technique ; Dental Porcelain ; chemistry ; Electron Probe Microanalysis ; Metal Ceramic Alloys ; chemistry ; Saliva, Artificial ; Surface Properties