Biomedical subjects
Publications and source records attributed to J D Gerrow.
During tooth preparation, the air and water from a dental handpiece occasionally cause painful stimulation of hypersensitive teeth. Use of mouthguards may be an alternative for the management of patients with tooth hypersensitivity.
This study determined the effect on articulator settings of using an arbitrary hinge axis as compared with the terminal hinge axis in orienting a computerized pantograph on a patient. The effect of an error in measuring the reference plane angle or clutch angle was also determined. Two subjects were pantographed 30 times by using the terminal hinge axis and 30 times by using the arbitrary hinge axis. Statistically the articulator settings obtained by using the arbitrary hinge axis and the terminal hinge axis were different, but the difference was small. One subject was pantographed on 18 occasions by using different reference plane angle and clutch angle settings. Analysis showed that 1-degree change in the reference plane angle setting produced approximately 0.9-degree change in the protrusive and orbiting path articulator settings. A 1-degree change in the clutch angle setting produced approximately 0.9-degree change in the progressive side shift settings. It was concluded that the terminal hinge axis should be used as the posterior reference point and the reference plane angle and clutch angle should be carefully recorded.
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Explore the source record for details and available documents.
This study determined the dimensional accuracy of dies made using a combination of four impression materials and three Type IV die stones. A metal die was prepared for a molar complete cast crown, and 10 stone replicas were made using 12 different combinations of impression materials and die stones. The distances between reference points on the metal and stone dies were measured in three directions with a traveling microscope. Analysis of variance and Duncan's MR comparisons (P less than or equal to .05) showed that all of the stone dies were larger than the metal die. Although there were significant differences between some of the impression material/die stone combinations, all of the stone dies were measured to be within 9 microns of each other. No one impression material/die stone combination consistently produced the smallest or largest die in the three measured directions.