Twelve dentulous patients, age 65 or older, with no medical or pharmacologic predisposition to gingival hyperplasia were enrolled in a controlled clinical trial to evaluate the effect of the unaided use of an ultrasonic toothbrush on supragingival plaque and gingival bleeding. Subjects used the ultrasonic toothbrush in lieu of their conventional toothbrushes for a 30-day period. Clinical measur...

This investigation was undertaken primarily to examine the possibility of hearing damage from industrial ultrasonic equipment. In the factory concerned, ultrasonic washers and drills were used at a number of different locations, and girls working 12 ft (3.6 m.) away from one bank of three small washers complained of unpleasant subjective effects which included fatigue, persistent headaches, nau...

Rats have developed antipredator defensive adaptations to protect themselves from the large number of animals that prey on them. One such adaptation is the ability to communicate by ultrasonic vocalization, which decreases the likelihood of detection by a predator. Almost all rat vocalizations are inaudible to the human ear as well, so laboratory studies of ultrasonic vocalization require speci...

Due to the increased use of high intensity ultrasonic devices, there is now a greater risk of worker exposure to ultrasonic radiation than there was in the past. Exposure to high power ultrasound may produce adverse biological effects. High power ultrasound, characterized by high intensity outputs at frequencies of 20-100 kHz, has a wide range of applications throughout industry. Future applica...

The principles of Ultrasonic Computed Tomography (UCT) are reviewed in this paper. The UCT is a powerful nondestructive technique in medicine and recently in industry to reveal an image of a slice of an object or body. The advantage of UCT over other conventional techniques in imaging is that a computed tomogram yields quantitative information about the section of interest. Experimental works o...

For the assessment performance of the ultrasonic flaw detector (UFD) equipment, various standard documents are referred to such as ASTM (E317), British Standard (BS-4331), Bureau of Indian Standard (IS-12666), and more. The methods of calibration are spelt in different tone in these documents while broadly serving the same purpose. In the present paper a comparison for the calibration procedure...

IN previous communications (Oksala and Lehtinen, 1959; Oksala 1960a, b), I noted that vitreous haemorrhages reflected echoes on the screen of an ultrasound equipment, and that these echoes were clearer if a fresh haemorrhage was involved. I also found that old haemorrhages, on account of the destruction of the vitreous, do not always become visible in ultrasonic examinations (Oksala and Lehtine...