摘要:

A method for the study of in vivo corrosion of various dental materials such as amalgams, gold, and chromium–cobalt alloys combining implantation and nuclear tracer techniques is described. Radioactive and nonradioactive implants were inserted subcutaneously in the backs of two groups of rats. After 5 days all animals were killed. The adjacent tissue was submitted to histopathological examination. The animals exposed to radioactive amalgams and chromium-cobalt disks with activity levels of 2—4 mCi showed local tissue reactions identical to those seen in sham-operated animals—-that is, inflammation and formation of granulation tissue. In contrast, the rats exposed to radioactive gold foils with activity levels of about 20 mCi suffered heavier damage at the implantation site, with loss of hair and some necrosis, in addition to the inflammation and granulation tissue formation. There was no kidney damage. The release of mercury, gold, or cobalt into the adjacent tissue and the kidney was measured by means of gamma-ray spectrometry.

ISSN:0001-6357    

DOI:10.3109/00016358309162313

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

A new dental gold alloy was investigated for the casting of prosthetic restorations. The binary alloy is composed of 10 weight-percent Co and 90 wt% Au. Studies of the structure of the alloy revealed a rod-eutectic structure with Co rods in Au matrix. By special heat treatment (solution treatment and precipitation treatment) the hardness was increased up to 280 Hv. The hardening effect caused by Co atom groups in the Au matrix was studied by transmission microscopy. Casting experiments were performed using conventional dental casting procedures. Metallographic studies revealed no Co rods in the surface layer of the castings after the heat treatment.

ISSN:0001-6357    

DOI:10.3109/00016358309162314

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

The short time distribution of58Co in mice that received a58CoCl2solution intravenously or intraperitoneally was examined by means of scintillation measurements. The serum, kidney, pancreas, spleen, liver, and heart were analyzed. Statistically significant differences in the distribution pattern after intraperitoneal and intravenous administration were noted for serum, kidney, liver, and heart 1 h after injection and for kidney, liver, and heart 5 h after injection. Only the heart showed a significant difference between the two administration methods 24 h after injection. Intravenous injections gave less variation between animals of the58Co distribution pattern than intraperitoneal injections.

ISSN:0001-6357    

DOI:10.3109/00016358309162315

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Cobalt—chromium alloy implants were placed subcutaneously in the neck region of mice, and the animals were killed after 8 weeks. The cobalt concentration was high in the connective tissue of the capsule formed around 5 out of 10 cobalt—chromium implants. In nine other tissues analyzed no statistically significant increases in the cobalt concentration were detected. The surgical procedure and the carrying of an implant did not influence the weight increase of the animals during the period of the experiment.

ISSN:0001-6357    

DOI:10.3109/00016358309162316

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

The translucency of the first generation of glass-ionomer cements to appear on the market was too low to be cosmetically satisfactory. In the present study the opacity of newer editions of glass-ionomer cements was evaluated and compared with that of a well-known composite resin. Disc-shaped specimens were placed on black and on white backings, the luminous reflectances measured and corrected to a specimen thickness of exactly 1 mm, whereafter the contrast ratio was calculated. The newer glass-ionomer cements were found to be more translucent than the first generation of glass-ionomer cements on the market. However, the opacity still needs to be reduced to reach the level of a composite resin. It was further established that early water contact results in a considerable increase in opacity.

ISSN:0001-6357    

DOI:10.3109/00016358309162317

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Dopamine neurons in the nigrostriatal subgroup of the basal ganglia are involved in the higher control of muscle tone and repetitive movements, possibly also in the masticatory muscles. For this reason, the effect of mechanical oral stimulation in combination with apomorphine-induced stimulation of dopamine receptors in the brain was experimentally studied in the rat. The masseter muscle tone during and after anesthesia was registered. A tachograph preamplifier and a bipolar electrode were used for the recording of summated potentials from the muscle. Dopaminergic stimulation increased the muscle tone. Oral sensory stimulation alone showed a tendency to increase the masseter tone, although the increase was not statistically significant. The increase of the tone with dopaminergic stimulation is presumably due to the fact that the dopaminergic system in the basal ganglia also controls the motor function of the masticatory muscles. Several pathological conditions of the mouth region, where a dopaminergic mechanism in the facilitation and inhibition of centrally coordinated jaw reflexes is obvious or possible, are discussed. Individual variation in neuronal dopamine synthesis, uptake, or receptor sensitivity may be one of the factors determining predisposition to masticatory disturbances both in experimental and clinical conditions.

ISSN:0001-6357    

DOI:10.3109/00016358309162318

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Data from an interview and clinical examination in a study of 440 randomly selected school children were analyzed with regard to relationships between signs and symptoms of functional disturbances and diseases in the stomatognathic system. A correlation was found between reported clicking sounds from the temporomandibular joint (TMJ) and pain when opening the mouth wide. Children who had been treated orthodontically or who were undergoing such treatment did not differ from other children in the frequency of signs and symptoms. Correlations were found between recurrent headaches and tenderness in TMJ and TMJ muscles. Reported pain in the temple region was also correlated to tenderness in the TMJ and TMJ muscles. Further correlations were found between recurrent headaches and oral parafunctions such as lip—cheek-biting and nail-biting and also among nail-biting, tooth clenching, tooth-grinding, and frontal dental wear. Children who reported oral parafunctions had more frequent interferences in RP and tenderness in TMJ muscles. There were correlations between irregular movements of the lower jaw and interferences in RP as well as mediotrusion interferences. Finally, a strong correlation was found between tenderness of the TMJ (laterally and posteriorly) and tenderness of the TMJ muscles.

ISSN:0001-6357    

DOI:10.3109/00016358309162319

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Plaque formed during a 5-day xylitol or sucrose chewing gum diet was used as an irritating agent in bone and macrophage culture. The release of hydrolytic enzymes was monitored. The contents of protein, DNA, and ATP were analyzed, to characterize plaque formed during different dietary periods. The release of glycosidases and phosphatases was lower in the presence of xylitol plaque when compared with sucrose plaque as an immediate reaction in macrophage cultures at 3 h and also in bone cultures at 3 days. The results indicate that xylitol plaque had a less irritating effect on macrophages and bones in vitro than sucrose plaque according to the parameters used in this study.

ISSN:0001-6357    

DOI:10.3109/00016358309162320

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Mesiodistal and buccolingual crown diameters were measured from casts of 1010 dentitions of schoolchildren from Northeast Iceland. Their teeth proved to be larger than in Europeans generally, being exceeded only by Australian Aborigines, some American Indian populations, and American Negroes. In comparison with Ohio Caucasians of Northwest European origin Icelanders showed clearly larger dimensions, less sexual dimorphism, and a different pattern of dimorphism. Crown indices were also distinctly different in Icelanders and Ohio Caucasians

ISSN:0001-6357    

DOI:10.3109/00016358309162321

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor

摘要:

Results of bending strength and deflection at fracture of intact and repaired denture base resin specimens were obtained. Both heat-cured and cold-cured resins of two different products were used. After storage in distilled water at 37°C for 1 month, some of the intact heat-cured specimens were dried in air at 21±1°C for 24 h before testing. This induced a lowering of the bending strength. There was no difference in strength between the two products. However, the intact heat-cured specimens of SR 3/60 showed higher results of deflection at fracture than Vertex. Repaired specimens had a bending strength between 42.9% and 61.2% compared with the intact heat-cured specimens tested immediately after storage in water. The repair performed with the low-viscosity self-cured resin resulted in higher bending strength values than when using repair material with the higher initial viscosity. Drying the broken heat-cured specimens for 24 h at 21±1°C before the repair and painting with monomer liquid on the fractured surfaces of the heat-cured resin was without effect on the bending strength of the repaired specimens.

ISSN:0001-6357    

DOI:10.3109/00016358309162322

出版商:Taylor&Francis    

年代:1983

数据来源: Taylor