Virtanen Antti S J
Institute of Physiology, University of Helsinki, Siltavuorenpenger 20 J, SF-00170 Helsinki 17 Finland.
Pain. 1985 Nov;23(3):279-288. doi: 10.1016/0304-3959(85)90106-X.
In the present study monopolar and bipolar electrode couplings were compared in electrical stimulation of intradental nerves. In experiments on cats the threshold current values of A- and C-fibres and the jaw-opening reflex were measured with both techniques using different durations of current pulses (0.2-50 msec). In human studies the perception and pain thresholds were determined in the same manner. In experiments on anaesthetized cats 170 intradental nerve units were recorded. Of these 118 were A-fibres (conduction velocity (CV) greater than 2 m/sec) and 52 C-fibres (CV less than or equal to 2 m/sec). The threshold current values (pulse duration 10 msec) of A-fibres were almost 2-fold (12.2 microA, S.D. = 7.9) and of C-fibres over 2-fold (91.3 microA, S.D. = 52.3) with bipolar stimulation compared to monopolar (6.9 microA, S.D. = 7.3 and 42.5 microA, S.D. = 21.5 respectively). The mean threshold of the jaw-opening reflex obtained with bipolar electrode coupling was about twice the value obtained with monopolar (8.2 microA, S.D. = 3.7 and 3.4 microA, S.D. = 0.7 respectively). In human experiments the mean perception threshold was 11.7 microA (S.D. = 6.7) with bipolar and 7.2 microA (S.D. = 3.2) with monopolar stimulation. The mean pain threshold was also higher with bipolar than with monopolar stimulation, 16.0 microA (S.D. = 8.8) and 10.3 microA (S.D. = 4.5) respectively. The subjective sensations were different with these two electrode couplings; the pain (at pain threshold level) induced by bipolar stimulation was experienced as sharp or cutting and with monopolar stimulation as dull or more indefinite. It is concluded that there is a marked difference in the electrical threshold values of pulpal nerves and perception threshold of individual human teeth between monopolar and bipolar tooth stimulation. The thresholds of the A-fibres measured from the cat canine tooth closely correspond to the perception thresholds of the human tooth, but the threshold values of the pulpal C-fibres were significantly higher.
在本研究中，对单极和双极电极耦合在牙髓神经电刺激中的情况进行了比较。在猫的实验中，使用不同持续时间的电流脉冲（0.2 - 50毫秒），用这两种技术测量A纤维和C纤维的阈值电流值以及张口反射。在人体研究中，以同样的方式确定感觉阈值和疼痛阈值。在麻醉猫的实验中，记录了170个牙髓神经单位。其中118个是A纤维（传导速度（CV）大于2米/秒），52个是C纤维（CV小于或等于2米/秒）。与单极刺激相比（分别为6.9微安，标准差 = 7.3和42.5微安，标准差 = 21.5），双极刺激时A纤维的阈值电流值（脉冲持续时间10毫秒）几乎是其2倍（12.2微安，标准差 = 7.9），C纤维则超过2倍（91.3微安，标准差 = 52.3）。双极电极耦合获得的张口反射平均阈值约为单极刺激时获得值的两倍（分别为8.2微安，标准差 = 3.7和3.4微安，标准差 = 0.7）。在人体实验中，双极刺激时的平均感觉阈值为11.7微安（标准差 = 6.7），单极刺激时为7.2微安（标准差 = 3.2）。双极刺激时的平均疼痛阈值也高于单极刺激，分别为16.0微安（标准差 = 8.8）和10.3微安（标准差 = 4.5）。这两种电极耦合引起的主观感觉不同；双极刺激引起的疼痛（在疼痛阈值水平）感觉尖锐或刺痛，单极刺激引起的疼痛则感觉 dull或更不明确。得出的结论是，单极和双极牙齿刺激在牙髓神经的电阈值和个体人牙的感觉阈值方面存在显著差异。从猫犬齿测量的A纤维阈值与人类牙齿的感觉阈值密切对应，但牙髓C纤维的阈值明显更高。 （注：原文中“dull”此处可能是表述有误，推测可能是“dull - like”之类更准确表达“类似钝痛的”意思，但按要求未作修改。）
