[Application of ultrasonography to periodontal diagnosis. 1. Standardization of examination]

Ultrasonic imaging equipment has been applied to periodontal diagnosis, but the standardization of this examination remains difficult. We found that a multiple reflected echo appeared on ultrasonography when the periodontal probe was inserted in the periodontal pocket. The purpose of this study was to investigate this multiple reflected echo as a reference point for ultrasonography and to measure the distances between the periodontal probe and alveolar crest in pigs by using ultrasonography. The multiple reflected echo disappeared under the following conditions: 1) when the change in horizontal position was more than 0.7 mm, 2) when the change in horizontal angle was more than 5 degrees, and 3) when the change in vertical angle was more than 20 degrees. The results in pig specimens showed that the difference in the distance from the top of the periodontal probe to the alveolar crest was less than 0.2 mm on ultrasonic and direct histological measurements. It was concluded that the multiple reflected echo of the periodontal probe can be used to standardize ultrasonographic examination.