Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

Objective

The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated.

Material and Methods

Disk specimens (diameter 10 mm and thickness 2.5 mm) were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1) air-abraded with 50-70-µm grain alumina (CON); 2) 1) + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA); 3) 1) + conditioned with a primer including a diphosphate monomer (MDP); 4) treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles.

Results

The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05) greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy.

Conclusion

Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.     

An Operating Microscope with Higher Magnification and Higher Resolution for Cerebral Aneurysm Surgery: Preliminary Experience—Technical Note

We describe a higher magnifying power operating microscope system to improve one method of high-quality microsurgical clipping for cerebral aneurysm in some cases. This higher magnification is achieved by a new lens design in the optical system, which makes the image of the object very clear at high magnifications (distinctiveness of 7 μm). This higher-resolution operating microscope system provides the surgeon with higher-magnified images (at the maximum of more than 30× magnifications as each working distance) in the operating field. The magnifications can be changed from low power (2.9×) to high power (62.0×) depending on the circumstances in a given procedure. We have used this operating microscope system on 11 patients with microsurgical clipping for cerebral aneurysms. Microsurgical treatment could be performed safely and precisely. All aneurysms were treated without any technical complications. We think that the use of this microscope would have potential benefits for microsurgical treatment for cerebral aneurysms because of better visualization.     

Comparison of Gas-less laparoscopy-assisted surgery, hand-assisted laparoscopic surgery and pure laparoscopic surgery for radical nephrectomy

BACKGROUND: We report our experience with Gas-less laparoscopy-assisted surgery (Gas-less LAS), hand-assisted laparoscopic surgery (HALS) and pure laparoscopic surgery (LS) for renal carcinoma and compare the characteristics and usefulness of these methods. METHODS: Seventeen, 14 and 16 patients were subjected to Gas-less LAS, HALS and LS, respectively. The study started with Gas-less LAS and then gradually shifted to HALS and LS. We evaluated the operative and postoperative parameters for each group. The learning curve effect was evaluated based on data from the first 10 cases of each group, which were operated on by the same surgeon and operation team. RESULTS: The learning curve of operation times in the LS group demonstrated that the operation time for this procedure is acceptable even in early-stage cases. Differences in mean operative time between the three surgical groups, excluding the conversion cases, were not statistically significant; however, there was a significant difference in blood loss volume between the groups (P 相似文献   

The effect of nifedipine on monocrotaline-induced pulmonary hypertension in rats

Effective drug therapy for pulmonary hypertension has not yet been developed. This study was designed to estimate the long-term hemodynamic and histopathological effects of nifedipine on severe pulmonary hypertension using animal models. Injection of one dose of monocrotaline produced subacute pulmonary hypertension in 7 week old Sprague-Dawley rats. Nifedipine (10 mg/kg) was administered intraperitoneally every day. For 5 weeks, bodyweight and hemodynamic parameters were measured, and right ventricle (RV) and left ventricle with septum (LV + S) were weighed separately. Medial thickness of the small pulmonary arterial wall was calculated by Suwa's method. Compared with the control group, the increase in right ventricular systolic pressure, total pulmonary resistance index, weight ratio of RV/(LV + S) and medial hypertrophy in the nifedipine-treated rats were significantly limited without causing systemic hypotension. These results suggest that treatment with nifedipine may also be effective in attenuation of pulmonary hypertension when applied to humans.     

Medium-term results of percutaneous transluminal balloon aortic valvuloplasty with Inoue balloon catheter for congenital aortic stenosis

Although percutaneous transluminal balloon aortic valvuloplasty (PTAV) has been performed for congenital aortic stenosis in infants and children for several years, its efficacy and the associated aortic regurgitation (AR) have not been widely discussed. Percutaneous transluminal balloon aortic valvuloplasty using an Inoue balloon catheter was performed for congenital aortic stenosis in 12 patients (4–16 years old) in this study. The systolic aortic valve pressure gradient ranged from 42 to 111 mmHg before PTAV and became < 50 mmHg immediately after PTAV in 10 cases (83%). Eight of these 10 patients had no increase in the gradient during subsequent observation for a period of 9–40 months. Aortic regurgitation increased immediately after PTAV in nine cases (75%). It increased from grade 1 to grade 2 in eight cases and from grade 1 to grade 3 in one patient; no significant enlargement of the left ventricular end-diastolic diameter and no significant change in the left ventricular end-diastolic pressure (LVEDP) or the cardiac index was observed during follow-up in these patients. There was a correlation between the diameter of the balloon and efficacy; an appropriate diameter was considered to be about 90% of the aortic annular diameter. Changes in the hemodynamic parameter after PTAV with an Inoue balloon were small in most patients and this procedure is considered to be a treatment that should be attempted prior to surgery for congenital aortic stenosis.     

Intraspinal Metastasis of Neuroblastoma -- Report of a Case Detected at Autopsy --

Metastasis to the brain or spinal cord parenchyma is extremelyrare in cases of neuroblastoma. We present a 3-year-7-month-old boy with neuroblastoma, stageIV, with intraspinal metastasis. He had no neurologic manifestationexcept incontinentia urinae and ataxia at the terminal stage.His cranial computed tomography scan showed high density areasin both cerebellar hemispheres which seemed to be distant metastaticmasses. At autopsy, the metastases in the cerebellum were foundto be due to dural infiltration but in the spinal cord parenchymaof the lumbar spine metastases were detected macroscopically.There were multiple distant metastatic areas near the roots,anterior and posterior. The neuroblastoma seemed to have spreadalong the roots by direct invasion from the meninges. In the future, the number of patients with metastasis into thebrain or spinal cord parenchyma will increase because patientswith progressive disease could live for a long time as a resultof intensive chemotherapy. Observation of these cases will behelpful to clarify the routes of metastasis to these areas.     

Expression of Sialylated LewisGangliosides in Cultured Lens Epithelial Cells from Rhesus Monkey

Monkey and human lenses contain essentially the same glycosphingolipids, and Lewis^xand sialylated Lewis^xepitopes are expressed on the terminal structure of neolactotetraosylceramide. However, monolayer cultures of lens epithelial cells from rhesus monkey expressed gangliosides GM3, GD3 and a small amount of GM1, but not sialylated Lewis^xepitopes. Eight-week-old cultures on various extracellular matrices resulted in morphological changes in lens epithelial cells. Monolayer of cells cultured on vitronectin or polylysine assembled into aggregates after 4 weeks of culture. Cells cultured on vitronectin expressed sialyl-Lewis^xgangliosides and did not exhibit GD3. On collagens, fibronectin and laminin elongated cells were observed in cells cultured for 8 weeks. Thus, the interaction between cells and extracellular matrices influenced morphology and glycosphingolipid composition in lens epithelial cells.     

Sympathetic skin response in diabetic children: Do diabetic children have diabetic neuropathy?

BACKGROUND: Abnormal sympathetic skin response (SSR) has been reported in adult patients with diabetic neuropathy. In addition, other studies have revealed abnormal SSR in diabetic patients not having autonomic symptoms and autonomic dysfunctions. These findings have been only obtained from adult patients. There have been few reports on the autonomic functions in diabetic children. Accordingly, it is not clear whether the autonomic neuropathy occurs in diabetic children. The aim of the present study is to clear autonomic function in children with insulin-dependent diabetes mellitus by SSR. METHODS: The SSR was measured in 28 normal healthy children and in eight patients with IDDM not having symptoms of dysautonomia. The SSR was elicited using 10 stimuli on programmed Nihonkoden Neuropack Sigma model machine. Following a single electrical stimulation, four SSR were recorded in both the palms and the soles simultaneously. RESULTS: The SSR were simultaneously obtained in 100% of the two groups. The amplitudes in the palms and soles were not significantly different between the two groups. The mean and shortest latency in the soles were significantly longer in the IDDM group than in the control group (P < 0.01). None of the measurements of SSR revealed correlation with duration of diabetes and onset of illness. CONCLUSIONS: Diabetic neuropathy may not have occurred in young patients having shorter duration of illness. Conversely, assuming that prolonged latency is abnormal, it may even have occurred in them. Follow up on these patients with prolonged latencies would be required.     

Trichosporon beigelii Pneumonia in a Patient with Malignant Histiocytosis

A 30-year-old previously healthy housewife presented with bilateralpulmonary infiltrates. She was treated with various antibioticsbut died with disseminated intravascular coagulation. Culturesof tracheal aspirates obtained prior to her death yielded Trichosporonbeigelii. Postmortem examination revealed T. beigelii pneumoniawith fungal dissemination in other organs. In addition, manyorgans were found to be infiltrated with atypical mononuclearcells which exhibited cytochemical properties of histiocytes.It was considered, therefore, that T. beigelii pneumonia developedon the basis of underlying malignant histiocytosis. T. beigeliiin her lung sections was fluorescently stained with rabbit antiserumto the fungus isolated from the patient. This is the first reportof Trichosporon beigelii pneumonia associated with malignanthistiocytosis.     

Stage–specific antigens of Hymenolepis microstoma recognized in BALB/c mice

Antigenicity of eggs (oncospheres), cysticercoids and adults (with immature segments only) of the bile duct tapeworm Hymenolepsis microstoma was analysed using immunoblotting techniques and indirect immunofluorescent antibody (IFA) techniques with immune sera of BALB/c mice (i) infected with different doses of cysticercoids, (ii) during patent or prepatent infection with the lumen phase of the parasite or (iii) sensitized with live or dead eggs. Antibody responses detected by IFA test and immunoblotting showed that antigenicity of eggs (oncospheres) differed from that of cysticercoids and adults. Single worm infections were sufficient to stimulate antibody responses. Mice which had patent infection showed strong antibody responses to all three (egg (oncosphere), cysticercoid, adult) antigens, while mice given two prepatent infections showed some antibody responses to cysticercoid and adult antigens only. Although the normal intermediate hosts of this parasite are arthropods, antibodies to some major egg (oncosphere) antigens were produced in mice given eggs of this parasite orally, either through inoculation of eggs or ingestion of faeces contaminated with eggs. Antibodies were not produced in mice dosed with non-viable eggs. The results are consistent with the hypothesis that cestode parasites express phase- (or stage-) specific antigens.