A study of bubbles in a rubber elastomer manipulated under clinical conditions.

One hundred addition reaction silicone impressions were made by students and faculty members using two types of syringes with two syringe tip sizes. A count of the bubbles in the impressions revealed a total of 439 with only one impression completely free of bubbles in either the posterior or anterior test regions. Faculty members, presumably more experienced, confirmed the last out-fewer bubbles hypothesis developed in a previous laboratory investigation, but some students did not. A pneumatically activated syringe produced no fewer bubbles than did the conventional hand-powered syringe but most of the students and faculty members thought it was advantageous. Half believed that more practice with it would be beneficial. We recommend that practicing dentists try to minimize bubbles by extruding the first part of the syringe contents onto the mixing pad or in a distant intraoral location before injecting around the critical tooth preparations.

Antimicrobial activities of some flavonoid compounds.

6 flavonoid compounds, namely kaempferol, quercetin, myricetin, rutin, naringin, and formononetin were separated from different plant materials. They were identified using column and paper chromatography techniques, and physicochemical methods were applied to determine their structure. Isolated flavonoids were tested for their antimicrobial property against different bacterial and fungal strains as test organisms.

Piezoelectric transducers for oral force monitoring.

A wide variety of instruments have been developed for oral force monitoring. Most of the instruments, however, have employed bite elements which were too thick for measurement of biting forces when the teeth are nearly in contact and probably stretched the stomatognathic muscular system beyond its maximum power of contraction. This paper reports on the use of piezoelectric transducers (quartz crystals, 1.5 mm thick) to monitor quantitatively biting forces in humans.

In vivo occlusal forces and moments: I. Forces measured in terminal hinge position and associated moments.

Microducers and modified cephalometric roentgenogram techniques were used to study maximum biting forces and moments in an adult male. The force at the second molar was approximately 10% greater than that at the first molar. At the second molar, the moment of force was approximately 15% less than its value at the first molar.

In vivo occlusal forces and moments: II. Mathematical analysis and recommendations for instrumentation specifications.

Mathematical models are derived to describe in vivo maximum occlusal force and moment data generated during mandibular terminal hinge closure for the molars and premolars and for the mandibular central incisors in the straight protrusive position. Recommendations for biting force instrumentation specifications are presented.