A STUDY ON DIAGNOSITIC METHODES OF DENTAL PULP BY PULSE OXIMETRY IN YOUNG PERMANENT TEETH AND DECIDUOUS TEETH

在这项研究中，我们成功地记录了透射光光体积描记法（TLP）从年轻人的牙髓，并检查其适用性的牙髓活力测试。本研究使用一位成人和六位儿童的上中切牙。在受试者上牙弓的石膏模型上制备受检牙齿的树脂帽，通过连接到单个树脂帽的光纤，将绿色发光二极管（LED，峰值功率为525 nm）照射受检牙齿的腭表面，并从牙齿的唇表面拾取穿过牙髓的透射光。将透射光的强度引导到CdS光导电池（峰值灵敏度在550 nm处），并通过交流耦合放大器将其强度变化记录为TLP，与受试者的手指体积描记图一起记录。在暗室中使用和不使用不透明黑色橡胶坝进行记录。在1例受试者中，根尖周浸润含1/80，000肾上腺素的2%利多卡因溶液，观察到TLP振幅的转变。结果表明：1）在正常恒牙中，成年人和青年人的TLP与手指体积描记同步。年轻人的TLP信号幅度更大，波形更清晰。2)从对牙髓的电刺激没有反应的脱位牙中轻微记录到TLP。但植入牙没有检测到明显的脉搏波。3)大坝的应用没有产生显着的信号减少。4)根尖周浸润2%LE后，TLP振幅逐渐降低，然后又升高。结果表明，TLP被认为是反映牙髓血流动力学，该系统将是有用的诊断牙髓活力的年轻恒牙，而不会引起任何疼痛感。

In this study, we succeeded to record transmitted-light photoplethysmography (TLP) from the dental pulp in young humans and examined its applicability to pulp vitality test. Upper central incisors of one adult and six children were used for this investigation. A resin cap of the examined tooth was prepared on the plaster model of the subjects' upper arch. A green light-emitting diode( LED, peak power at 525nm) illuminated the palatal surface of the examined tooth via an optical fiber attached to the individual resin cap, and the transmitted-light through the pulp was picked up from the labial surface of the tooth. The intensity of the transmitted-light was guided to a CdS photoconductive cell (peak sensitivity at 550nm), and its intensity change was recorded as TLP through AC-coupled amplifier together with the finger plethysmography of the subjects. Recordings were made with and without opaque black rubber dam application in a dark room. In one subject, 2% lidocaine solution containing 1/80,000 epinephrine was periapically infiltrated and the transition of the amplitude of the TLP was observed. Results obtained were as follows : 1) TLP, synchronous with the finger plethysmography, was recognized from sound permanent teeth of an adult and the young subjects. The signal amplitude of the TLP was larger and the waveform was much more clearer with the young subjects. 2) TLP was slightly recorded from luxated teeth which did not respond to electrical stimulation to the pulp. But with an implanted tooth no obvious pulse wave was detected. 3) The dam application did not produce a significant signal reduction. 4) Periapical infiltration of 2%LE produced a gradual decrease of the amplitude of TLP and then was followed by an increase. Results indicated that TLP is considered to reflect pulpal haemodynamics and this system would be useful for the diagnosis of pulpal vitality of the young permanent teeth without eliciting any pain sensation.