Ultrasonic device for measuring periodontal attachment levels

Abstract

Periodontal disease is manifested clinically by a degradation of the ligament that attaches the tooth to the bone. The most widely used diagnostic tool for assessment of periodontal diseases, measurement of periodontal attachment loss with a manual probe, may overestimate attachment loss by as much as 2 mm in untreated sites, while underestimating attachment loss by an even greater margin following treatment. Manual probing is also invasive, which causes patient discomfort. This work describes the development and testing of an ultrasonographic periodontal probe designed to replace manual probing. It uses a thin stream of water to project an ultrasonic beam into the periodontal pocket, and then measures echoes off features within the pocket. To do so, the ultrasonic beam must be narrowed from 2 (the diameter of the transducer) to 0.5 mm (the approximate width of the periodontal pocket at the gingival margin). The proper choice of transducer frequency, the proper method for controlling water flow from the probe, and a model for interpreting these echoes are also addressed. Initial results indicate that the device measures echoes from the hard tissue of the tooth surface, and that the periodontal attachment level can be inferred from these echoes.

Clinical comparison of an ultrasonographic periodontal probe to manual and controlled-force probing

“…A signal processing technique based on peakpicking and smoothing algorithms was used to analyze the ultrasonographic data [78]. To obtain pocket depth data, a processed signal for each probing site was visually examined by five individuals experienced in ultrasound signal analysis.…”

Lateral distribution of ultrasound velocity in horizontal layers of human teeth

“…Therefore, a complete quantification of visco-elastic parameter distributions is helpful or may even be considered as a prerequisite for utilizing ultrasonographic probes as diagnostic tools that localize any invisible internal damages, too. 22 Recently, a partial quantification of the vertical distribution of sound velocity approximates the initial corono-apical decrease in the longitudinal wave velocities ͑c L ͒ of 21 dentin specimens of extracted human teeth by c L = 4224 − ͑257 ln͑y͒͒. 9 The former data are based on a single relative tooth width portion and a standardization that accounts for a distinct number of roots ͑x = 0.7w for teeth with a single root and a substitute of x = 0.826w for teeth with two or more roots͒.…”

Ultrasonic Periodontal Probing Based on the Dynamic Wavelet Fingerprint

“…While these efforts proved the feasibility of ultrasonic imaging in dentistry, this version of the technique could not detect periodontal attachment loss, and failed to gain clinical acceptance. Recently, researchers have begun exploring new uses of ultrasound in dentistry [36,37,38,39] and studies have been conducted using ultrasound to image the periodontal pocket space by aiming the transducer apically into the pocket from the gingival margin [40,41,42,43,44,45,46]. The major technical barrier to this approach is providing an efficient coupling medium for the ultrasonic wave into the thin (0.25-0.5 mm) periodontal pocket.…”

“…As an initial effort to automate interpretation of the echoes, a time-domain procedure was developed to simplify the waveforms and infer the depth of the periodontal pocket [44,45,46]. This procedure used a slope-detection algorithm to pick peaks in the A-scan signal, followed by smoothing and averaging operations to eliminate small random variations.…”