Quality Of Impression Research Articles

A study of the quality of impressions for anterior crowns received at a commercial laboratory.

A report is presented of a study which was carried out to investigate the standard of impressions for anterior crowns received at a commercial dental laboratory in Great Britain. Aspects examined were the type of tray and its suitability to the impression technique used, fixation of the impression to the tray, the method of storage in transit, contamination, defects on the preparations and defects elsewhere affecting the occlusion. The quality of the actual preparation was not examined in this study. Similar details were noted for the opposing impression. Of the 50 cases examined only 12 were recorded as totally satisfactory, with 26 cases being recorded as not being of an acceptable standard for the construction of an adequate restoration. The results are presented with the conclusion that in this survey the general quality of impression was unacceptable.

Test device for measuring the fit of hearing and related devices

A measuring device for checking the tightness of an ear impression mold serving as pattern for the production of an otoplastic and/or of an otoplastic inserted in the auditory passage of an ear through which an air pressure deviating from the air pressure prevailing on the outside can be produced, via an air permeable connection, in the inner space defined by the ear drum and the ear impression or otoplastic. Through the device changes in the generated deviating air pressure can be measured. The air permeable connection is connected to a pump serving for the generation of the deviating air pressure via a pressure chamber whose volume is a multiple of the volume of the inner ear space. A control circuit presetting the timing of the pumping and measuring process is provided. The device is insensitive to differences in the volume of the inner ear space and produces reproducible test results which reliably indicate the quality of the ear impression of otoplastic.

4.末梢静脈, 静注法DSAの臨床評価(II.ディジタルラジオグラフィーの現状と将来)

Intravenous digital subtraction angiography of 434 cases has been evaluated in the National Medical Center Hospital. All these cases were injected from peripheral vein with insertion of 5 cm length cannula of 19G. After the injection of contrast material, 5% glucose solution is continuously infused. The evaluation has been performed with the image impression quality which is superior or inferior compared with a selective angiogram. Excellent means superior quality to selective angiography, good means compatible to angiography of catheter technique, fair means inferior to the angiography and in these case the diagnosis is easily made, but poor means that image is obscure and failed to make a correct diagnosis. The volume of contrast material is also checked with image quality. Twenty ml and 40 ml groups were divided. Among the 434 cases, 30 cases were excellent and 50 cases were poor. As much as the volume of the contrast material is concerned, 6 cases were observed to be excellent and 65 good in the 20 ml group of 234 patients ; and 23 cases were proven to be excellent and 120 good in the 40 ml group of 207 patients. In the proximal part of extremities, there were very few differences in image quality between the 20 ml and 40 ml groups. However, in the distal part, the 40 ml group showed superior quality, and 40 ml of the contrast material injection is recommended to demonstrate the peripheral vessels. The peripheral venous injection DSA is a very useful procedure of angiogram for the outpatients and pediatrics and cases thought to be serious. This IVDSA system is one of the less invasive and advantageous image modalities.

The perception of shape as a function of inclination.

This is a descriptive study of the various judgments of shape which are spontaneously made when the inclination of an object is varied. The full range of inclinations is examined, using independent and unsophisticated subjects at each inclination, and recording subjects' descriptions.The chief findings are: (1) Two main judgments are possible: judgments of real shape (R), which approximate to the true shape at all inclinations; and judgments contrasted with these (not‐real or N), which show typically a compromise between true and retinal shape. (2) Some subjects (group RN) are spontaneously aware of both possibilities. They describe the N judgment as an attempt to equate on the basis of a direct, instantaneous, visual impression; whereas the R judgment involves ‘allowing for the slope’. These subjects predominate at greater inclinations. (3) The remaining subjects (group RO) are spontaneously aware of the R possibility only. For these subjects, the R judgment seems to approximate closely to that quality of direct visual impression which for group RN characterizes the N judgment.It is suggested that judgments of real shape involve a skill. Group RN are in an ‘investigating’ frame of mind, and offer an analysis of this skill. Group RO, in an ‘unreflecting’ frame of mind, take it for granted. Determining factors are also noted in the experimental situation and the instructions. It is suggested that previous studies fail to take adequate notice of these factors, and so give partial accounts.