摘要:

Disks of gold, amalgam, composite material, silicate cement and a piece of enamel were carried in the mouth for 2 hours. The disks and the enamel piece were then submitted to Auger analysis in conjunction with Ar sputtering to obtain chemical depth profiles of the formed integuments. Carbon, nitrogen and oxygen were found as constituents of the surface layer on gold, amalgam, composite and enamel indicating an organic film on these surfaces. On silicate cement no such film could be detected. The depth profiles showed that both calcium and sulfur were differently distributed in the integuments. The elements copper, tin and silicium were found in the films on gold, amalgam and composite, respectively, thus corroborating earlier observations that the integuments on different materials vary in chemical composition.

ISSN:0001-6357    

DOI:10.3109/00016358209012721

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Occlusal conditions and skeletal facial morphology in patients with amelogenesis imperfecta were studied in order to reveal a supposed relationship between skeletal morphology and a high prevalence of open bite. Records and dental casts were available for 26 cases, and lateral cephalograms in 19 of these. An open bite was present in 11 patients of both sexes, but was more frequent in males than in females. It occurred in cases with enamel defects of hypomineralisation type as well as in those with hypoplasia.15 linear and 10 angular measurements from the cephalograms were compared with those of matched controls. Both males and females with enamel defects were found to have significant skeletal features, characteristic of the so-called open bite skeletal deformity. The skeletal deviation was more marked in males than in females. The pattern of an open bite skeletal deformity, although less marked, was also present in patients with the enamel defect but without an open bite occlusion. The open bite occlusion frequently found in cases of amelogenesis imperfecta is therefore considered to be of skeletal origin, although the causal relationship between the enamel defect and the skeletal deformity remains to be explored.

ISSN:0001-6357    

DOI:10.3109/00016358209012722

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Effects, of volume fraction filler and silane treatment on compressive yield strength of experimental PMMA composites were investigated and explained by use of the Coulomb yield criteria. The results showed that an increase in volume fraction filler will not automatically increase compressive strength, and that the silane treatment is of greatest importance to optimize the compressive strength of a composite.

ISSN:0001-6357    

DOI:10.3109/00016358209012723

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Arthrography in combination with cineradiography was performed on five temporomandibular joint (TMJ) autopsy specimens with clicking. Clicking was found to be associated with rapid movement of disc and condyle and with a bulge in the condylar path. Clicking and movement in autopsy specimens appeared to be similar to that in patients with TMJ clicking. Four joints demonstrated clicking during protrusion, but this did not occur unless preceded by clicking late during a previous retrusion. In these four joints the disc moved in the opposite direction to the condyle in association with clicking. The findings indicated that the condyle, both at protrusion and retrusion, slipped over the posterior ridge of the disc in association with clicking forming the bulge in the condylar path. In the fifth joint, bulges in the condylar path associated with clicking were registered in the same location both during protrusion and retrusion. In this joint the disc and condyle moved coordinately and were possibly slipping over an obstacle on the temporal articulating surface forming the bulges in association with clicking.

ISSN:0001-6357    

DOI:10.3109/00016358209012724

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

High-speed cinematography using 250 frames/s and 500 frames/s was performed on five temporomandibular joint (TMJ) autopsy specimens with clicking, and four without. The joint compartments were visualized by removal of the lateral part of the capsule and disc. In joints without clicking, even and smooth movement of condyle and disc was observed. In joints with clicking the rapid movement of disc and condyle in association with clicking was delineated. In four joints with reciprocal clicking, the clicking was registered at the instant the condyle hit the temporal component after having slipped over the posterior ridge of the disc. In the fifth joint with clicking, movement between condyle and disc was coordinated in association with clicking. At dissection all joints demonstrated deviation in form of both the temporal and mandibular components.

ISSN:0001-6357    

DOI:10.3109/00016358209012725

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

Studies by means of infrared multiple internal reflection spectroscopy of ultraviolet and visible light polymerized composite resin materials indicated that the degree of conversion below the surface is nearly constant for most of the materials investigated until a depth is reached where the degree of conversion rapidly decreases. The maximum depth of cure has also been measured for some proprietary dental composite resin materials. This investigation has demonstrated that the conversion at different depths and the maximum curing depth are dependent on the composition of the composite filling material, light source, and exposure time. With respect to the activating system it was found that with visible light activated materials larger curing depths were obtained than with ultraviolet light activated materials. Better results with respect to curing depth were also obtained with materials containing conventional inorganic fillers than with those containing so-called microfillers.The limiting factor for total curing depth, and conversion as a function of depth of the proprietary light activated composite resin materials used in this investigation is assumed to be light scattering. Based on a semi-empirical scattering function the influence of particle size and refractive index of the particles and the organic medium on the light scattering were assessed. Maximum scattering occurs when the effective size of the particles is approximately half the wavelength of the activating light. This is the case with a microfill material activated by ultraviolet light.

ISSN:0001-6357    

DOI:10.3109/00016358209012726

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor