Glenn Haegerstam

Perception of pulpal pain as a function of intradental nerve activity

&NA; The purpose of the present investigation was to find neurophysiological correlates of pain perception. The magnitude and time course of perceived pain was successfully related to the neural discharge evoked by rapid cooling of the tooth surface in 6 dental patients whose lower incisors were to be extracted for prosthodontic reasons. Two cavities were prepared on the facial surface of human lower incisors. The cavities were deepened using hand driven instruments until the pulp was visible through a thin layer of dentin. A metal tube was placed in contact with amalgam on each cavity bottom and fixed in place by composite filling material. The tubes were connected to standard equipment for electrophysiological recordings by a flexible circuit. The magnitude of perceived pain was assessed by a cross‐modality matching to finger span in combination with sensory verbal pain descriptors and magnitude estimation. The striking agreement between the integrated nerve activity, probably of the A&dgr; type and pain perception, is of great importance from the methodological point of view since it strongly argues in favor of the appropriateness of the techniques applied here to elucidate the neural substrate of some types of nociception and also to evaluate various means of relieving such pain.

Influence of vasodilator substances on pulpal blood flow in the cat

The objective of the study was to determine the response in the pulpal blood flow to vasodilator substances at different levels of vasomotor tone.Simultaneous determinations of iodide disappearance rate (k-value) from dentinal cavities and, as control, from the adjacent alveolar submucosa were performed on anesthetized cats. Changes in k-value reflected changes in blood flow. Close i.a. infusion of acetylcholine, histamine and bradykinin did not influence pulpal microcirculation when the sympathetic nervous tone was low. At a higher level of nervous vascular tone, obtained by direct electrical stimulation of the cut sympathetic cervical trunk, the substances were shown to increase the pulpal blood flow. Papaverine and warming had a more pronounced vasodilator influence on pulpal blood flow, suggesting the presence of a local myogenic vascular tone regulating the exchange function, which was unaffected by acetylcholine, histamine and bradykinin. These substances were thus shown to act as inhibitors of symp...

Relation between intradental nerve activity and estimated pain in man--a mathematical model.

Abstract Intradental nerve activity (INA) induced by cold stimulation of human teeth is regularly accompanied by pain perception. In this study a mathematical model was developed in order to quantify the relationship between INA and pain. In 5 patients (45 experiments) INA was recorded using electrodes implanted in lower incisor teeth. Brief cold stimulations induced bursts of INA. The intensity of the resulting pain was simultaneously evaluated by means of an intermodal matching technique, finger span. The relationship between perceived pain and the integrated INA was analyzed using various mathematical operations (inter alia Fourier analysis) by means of a computer. A transfer function which describes the pain response following INA was found. This preliminary mathematical model, which is characterized by 5 parameters, consists of 2 parts, one which responds to fast changes in the afferent nerve signal, and another which reacts with a delay. The validity of the model has been tested, and it was found that the model consists of an adequate number of parameters and their cross‐interaction is low. The analysis indicates that the parameters which determine the pain response following INA can be quantified and that they might be used as a measure of the efficacy of various pain relieving procedures.

The ability of a mathematical model to evaluate the effects of two pain modulating procedures on pulpal pain in man

&NA; The ability of a mathematical model to evaluate the effects of two different pain modulating procedures (partial nerve block and vibration) on acute experimental pulpal pain was studied. The results were also compared with placebo procedures and it was shown that the model could accurately quantify the parameters that determine the pain response following cold‐induced intradental nerve impulse activity (INA). The most effective pain relieving method was found to be partial nerve block which induced significant parameter alterations reflecting decreased pain sensation and increased reaction time. Thus, it was shown that the present mathematical model is a useful tool enabling detailed analysis of differences in pain relieving procedures on human pulpal pain mediated by nerves of the A type.

Evaluation of a mathematical model analysing the relation between intradental nerve impulse activity and perceived pain in man

In this investigation the usefulness and accuracy of the parameters of a mathematical model for the analysis of the effectiveness of different pain relieving procedures on pulpal pain were studied. The investigation was carried out using a previously developed mathematical/biological model on data from original subject recordings of Intradental Nerve Impulse Activity (INA) and pain estimations. Computer simulated INA and pain estimation curves were also used to enable calculation of the mathematical and biological conditions that are essential for the actual mathematical/biological model, and to facilitate the interpretation of the parameters of the model. It was shown by means of both real and simulated data that the mathematical model is well suited for the analysis of the effectiveness of some pain relieving procedures on pulpal pain. It was also shown that, by means of three new variables, the model could be made even more accurate and useful for this application.

A COMPARISON BETWEEN DIFFERENT MODELS OF THE RELATION BETWEEN RECORDED INTRADENTAL NERVE IMPULSE ACTIVITY AND REPORTED PAIN IN MAN

In this study three different models of the relation between intradental nerve impulse activity (INA) and pain report, expressed by finger-span (FS), in man were investigated. The techniques were (i) a previously described mathematical model, (ii) the relation between the Areas of INA and FS and (iii) the relation between the Peaks of INA and FS. Their usefulness in 533 clinical experiments on 15 subjects were evaluated by means of a statistical analysis of the variability and accuracy of the models. It was shown that the mathematical model was the most accurate and stable method of the three different methods investigated. This was indicated by, among other things, a significantly smaller variability for the mathematical model within experimental sessions than between sessions. The two other methods were found to be of less scientific value since they had an undesired high variability within sessions, and also showed contradicting results during control conditions.

Lack of disability in patients with chronic orofacial pain A retrospective study

Although patients with chronic orofacial pain are frequently disabled, the disability is not necessarily due to the orofacial pain: various other factors may contribute. This retrospective study investigated the possible relationship between reports of pain, fatigue, disease conviction (DC), and denial of psychologic factors as explanation of the suffering (P-S) and limitations in occupational, domestic, physical, social, and sexual activities. The subjects comprised 30 patients referred to the Facial Pain Diagnostic Group at the Karolinska Institute, School of Dentistry, Huddinge, Sweden. None of the disability measures were significantly (p < or = 0.01) correlated with the facial pain reports. Fatigue was not correlated with degree of reported pain. DC was significantly (p < or = 0.01) correlated only with the minimum pain intensity. P-S was negatively correlated (p < or = 0.01) with maximum pain intensity and pain distribution (number of zones) outside the face. In 50% of the patients chronic orofacial pain was the formal reason for their occupational disability. However, such disability was related only to pain distribution (number of zones) outside the face. Social activity was negatively correlated (p < or = 0.01) with fatigue and positively correlated (p < or = 0.01) with P-S. It is suggested that the findings could be satisfactorily explained by a symptom perception hypothesis.

Technik der regionalen Anästhesie in der Zahnheilkunde

Fur den Zahnarzt ist eine Injektion eine alltagliche Sache, fur den Patienten jedoch sehr haufig eine unangenehme Erfahrung. Beruhigende Worte und psychologische Unterstutzung sind unerlaslich, um das Vertrauen des Patienten in den Arzt zu starken.

Differencies in pain modulating effects of infiltration with lidocaine or adrenaline on pulpal pain in man evaluated by means of a mathematical model

DIFFERENCIES IN PAIN MODULATING EFFECTS OF INFILTRATION WITH LIDOCAINE OR ADRENALINE ON PULPAL PAIN IN MAN EVALUATED BY MEANS OF A MATHEMATICAL MODEL. H.Sandberg,*U.Fors, L.Edwall & G.Haegerstam. Dept. of Endodontics, Karolinska Institute, Aim of investigation: Infiltration anaesthesia in dental practice is mostly performed using combinations of Lidocaine and Adrenaline. Previous studies have indicated that by blocking blood flow, Adrenaline itself might relieve pain. Using a mathematical model analyzing the relation between the Intradental Nerve Activity (INA) and pain intensity we studied if injection of Adrenaline (12.5pg/ml) may induce any pain modulating effect as compared to Lidocaline (ZOmo/ml). Methods: Ten sessions were performed in three volunteers. The INA was recorded from electrodes implanted in lower incisor teeth and the pain was measured by means of an intermodal matching technique. After recording the control INA-pain relation, injection with Adrenaline or Lidocaine was performed, followed by new recordings until the initial relation was achieved. The recordings of the two groups were then analyzed by means of the mathematical model giving the values of the parameters that determine the actual subjects reaction to painful dental stimuli. The parameters were then compared between the groups to detect any significant change in value. Results: The analysis indicated that both the infiltrations with LidoCaine and Adrenaline modulated the pain response after the injections. The effects were of short duration and it was also indicated that the INA-pain relation was affected differently. Conclusions: Both injection with Lidocaine and Adrenaline modulated the pain response in the subjects. It was also indicated that they had different modes of action as reflected by alterations of the parameters of the INA-pain relation.

Blockade der Nervenleitung

Die reversible Nervenblockade durch die richtige Anwendung von Lokalanasthetika ist eine unschatzbare Hilfe in der Medizin. Diese lokalanasthetisch wirkenden Substanzen gehoren zu den Verbindungen mit Ester- bzw. Saureamidgruppen.