Assessment of visco-elasticity of the periodontium by means of simultaneous recording fo tooth oscillation and peripheral circulation

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The tooth pulsates due to blood flow through capillary vessels of the periodontal membrane. The purpose of the present research was to obtain an index for assessment of the peripheral circulation and visco-elasticity of the periodontium through the measurement of tooth oscillation with an Amorphous core multivibrator senser.First, to obtain the norm of tooth oscillation of the unaffected periodontium, the recordings of 23 central incisors with healthy periodontal membrane were analyzed. (1) The mean amplitude of the labio-lingual derection (0.59mum) and the variations were smaller than the tooth axis deirection (0.88mum) . (2) The tooth pulsated as late as 0.11-0.13 sec after R-wave of electrocardiograph. (3) The three measurement points at the labial surface moved in a similar direction in 16 teeth, and showed different trends in the others. (4) Two patterns of the power spectrum were observed. One in which the power of the spectrum decreased gradually with increased frequency, the other was that the depression is seen at the midst of the spectrum.Second, the possibility of the index of the optimum force were estimated from the measurement of tooth oscillation at the beginning of the tooth movement, a month after the first premolar, the upper left canine were pushed by the orthodontic force of about 0,20,60 and 120 grams. At resting condition of 0 gram, the pulsation synchronized with the heart rate in which the amplitude was 0.15 mum. The amplitude at the force of 20 grams increased slightly. This suggested that the blood flow was still secured under the pressed periodontal membrane. At the force of 60 and 120 grams, the amplitudes were almost 0.1 and under 0.05 mum, respectively. This decreased amplitude indicated that the blood flow in the periodontal membrane was impeded as the force imcreased.