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Biomedical subjects

P Kemppainen

Publications and source records attributed to P Kemppainen.

At least 19 recordsLinked to original sources
PubMed2006

Capsaicin-induced local elevations in collagenase-2 (matrix metalloproteinase-8) levels in human gingival crevice fluid.

BACKGROUND AND OBJECTIVES: Application of capsaicin on alveolar mucosa provokes pain and neurogenic vasodilatation in the adjacent gingiva. Pain-associated inflammatory reactions may initiate expression of several pro-inflammatory mediators. Collagenase-2 (matrix metalloproteinase-8: MMP-8) is the major destructive protease, especially in the periodontitis-affected gingival crevice fluid (GCF). With this background, we wished to study whether capsaicin stimulation of alveolar mucosa can induce changes in the GCF MMP-8 levels. MATERIAL AND METHODS: For 10 generally and periodontally healthy human volunteers, capsaicin (3%)-moistened filter paper was applied unilaterally to the buccal alveolar mucosa on the anterior maxilla. GCF samples were collected from the tooth at the stimulation site and from several other incisors in the upper jaw. MMP-8 levels and molecular forms in GCF samples were determined by immunofluorometric assay (IFMA) and western immunoblotting, respectively. RESULTS: Capsaicin stimulation of the alveolar mucosa induced significant local elevations in levels and activation of MMP-8 in GCF of the adjacent teeth. Western immunoblot revealed that both neutrophil- and mesenchymal-type MMP-8 isoforms were elevated and activated, together with 110 kDa high-molecular size MMP-8 species. This capsaicin-evoked MMP-8 elevation lasted several minutes after stimulation. During the experiments, no marked changes occurred in MMP-8 levels in the GCF of distantly located teeth. CONCLUSIONS: These results suggest that capsaicin-evoked neurogenic gingival inflammation can trigger the expression and activation of MMP-8 in GCF of the adjacent teeth.

Adult↗
PubMed2005

Cortical representation of experimental tooth pain in humans.

Cortical processing of electrically induced pain from the tooth pulp was studied in healthy volunteers with fMRI. In a first experiment, cortical representation of tooth pain was compared with that of painful mechanical stimulation to the hand. The contralateral S1 cortex was activated during painful mechanical stimulation of the hand, whereas tooth pain lead to bilateral activation of S1. The S2 and insular region were bilaterally activated by both stimuli. In S2, the center of gravity of the activation during painful mechanical stimulation was more medial/posterior compared to tooth pain. In the insular region, tooth pain induced a stronger activation of the anterior and medial parts. The posterior part of the anterior cingulate gyrus was more strongly activated by painful stimulation of the hand. Differential activations were also found in motor and frontal areas including the orbital frontal cortex where tooth pain lead to greater activations. In a second experiment, we compared the effect of weak with strong tooth pain. A significantly greater activation by more painful tooth stimuli was found in most of those areas in which tooth pain had induced more activation than hand pain. In the medial frontal and right superior frontal gyri, we found an inverse relationship between pain intensity and BOLD contrast. We concluded that tooth pain activates a cortical network which is in several respects different from that activated by painful mechanical stimulation of the hand, not only in the somatotopically organized somatosensory areas but also in parts of the 'medial' pain projection system.

Adult↗
PubMed2005

Temporomandibular disorder subtypes according to self-reported physical and psychosocial variables in female patients: a re-evaluation.

Several studies support the relevance of psychological and psychosocial factors in the assessment and management of chronic musculoskeletal pain disorders, including temporomandibular pain disorders (TMDs). The aim of this study was to re-evaluate subtyping approach used in an earlier study (TI Suvinen, KR Hanes, JA Gerschman, PC Reade. J Orofac Pain 1997;11:200) and to compare perceived physical symptoms, psychological, coping and psychosocial variables between subtypes of patients who seek treatment for their temporomandibular pain and dysfunction. A total of 41 consecutive female patients were assessed multiaxially for physical symptoms, coping style and effectiveness and illness behaviour by a previously validated Temporomandibular Pain Dysfunction Questionnaire (TI Suvinen, KR Hanes, JA Gerschman, PC Reade. J Orofac Pain 1997;11:200). Additional measures of psychosocial variables included the global scores of the Beck Depression and Anxiety Inventory and Part I of the Multidimensional Pain Inventory. Subtypes were generated using an iterative partitioning method, k-means cluster analysis. Three clusters were identified and termed as Simple (22%), Intermediate (41%) and Complex (37%) temporomandibular disorders subtypes. Significant differences (P < 0.05) were found between clusters in psychological (coping style and effectiveness, disease conviction and affective disturbance) and in psychosocial variables (daily interference and social, work and family satisfaction), but not between physical variables. The results support previous studies that have shown differences in psychosocial variables in the presentation and subtyping of TMDs and the biopsychosocial orientation in assessment. The findings need to be reverified in a larger sample along specific physical diagnoses, but it is tentatively proposed how the three subtypes could be used in the classification of temporomandibular pain patients to guide management, based on the constellation of predominant psychological and psychosocial illness impact variables.

Adaptation, Psychological↗
PubMed2005

Painful tooth stimulation elevates matrix metalloproteinase-8 levels locally in human gingival crevicular fluid.

Recent studies have demonstrated that pulpal pain can induce neurogenic inflammatory reactions in gingiva and the expression of pro-inflammatory neuropeptides in gingival crevicular fluid (GCF). Neuropeptides co-ordinate the activity of immuno-effector cells and may influence the secretion of matrix metalloproteinase (MMP)-8, the major tissue-destructive protease in GCF. With this background, we studied whether experimental pulpal pain can trigger changes in GCF MMP-8 levels. The molecular forms of MMP-8 in the GCF of stimulated and non-stimulated teeth were analyzed by Western immunoblot, and MMP-8 levels by quantitative immunofluorometric assay. Painful stimulation of the upper incisor provoked significant elevations in GCF MMP-8 levels of the stimulated tooth. Western immunoblot revealed elevations in both neutrophil- and mesenchymal-type MMP-8 isoforms. At the same time, the GCF MMP-8 levels of the non-stimulated teeth were not changed. Analysis of these data indicated that pulpal pain can induce local elevations in MMP-8 levels in GCF.

Adult↗
PubMed2003

Vertical jaw separation and masseter muscle electromyographic activity: a comparative study between asymptomatic controls & patients with temporomandibular pain & dysfunction.

The aims of the present study were to assess the relationship pattern between bilateral masseter muscle electromyographic (MEMG) activity recordings and vertical jaw separation (VJS). Asymptomatic subjects (n = 15) were compared with age and gender-matched patients (n = 18) with temporomandibular pain and dysfunction (TMPD); before and after undergoing interocclusal appliance (IOA) therapy for 4 months. In asymptomatic subjects a bilateral minimum MEMG activity was found in a 'resting zone' at approximately a quarter of maximum mandibular opening (mean, 15.4 mm of VJS; range, 5.5-22.5 mm including overbite). No overall relationship between MEMG and VJS was shown for patients with TMPD. After successful IOA therapy, the majority of TMPD patients (14 of 18) showed normalization of the relationship between MEMG and VJS, but electromyographic assessment was not found to be of value as a single objective assessment parameter in evaluating the resolution of TMPD or the effectiveness of IOA therapy.

Adolescent↗
PubMed2003

Differences between tooth stimulation and capsaicin-induced neurogenic vasodilatation in human gingiva.

Animal experiments have shown that the application of capsaicin to oral mucosa leads to a neurogenic inflammation associated with blood flow elevations in gingivomucosal tissues. In this investigation, we measured the tooth stimulation and capsaicin-evoked blood flow responses in maxillary gingiva in humans to study whether axon-reflex-mediated vasodilatation crosses the midline of the maxilla. The vasoactive reactions were mapped by laser Doppler imaging. Unilateral stimulation of alveolar mucosa and attached gingiva by capsaicin evoked a distinct neurogenic vasodilatation in ipsilateral gingiva, which rapidly attenuated at the midline. Capsaicin stimulation of alveolar mucosa provoked clear inflammatory reactions. In contrast to capsaicin stimuli, tooth stimulation produced symmetrical vasodilatations bilaterally in the gingiva. The ipsilateral responses were significantly smaller during tooth stimulation than during capsaicin stimuli. Analysis of these data suggests that capsaicin-induced inflammatory reactions in gingivomucosal tissues do not cross the midline in the anterior maxilla. The enhanced reaction found during stimulation of alveolar mucosa indicates that alveolar mucosa is more sensitive to chemical irritants than attached gingiva.

Adult↗
PubMed2001

Blood flow increase in the human lip after high-intensity tooth stimulation is not based on cholinergic mechanisms.

The purpose of this study was to investigate whether parasympathetic cholinergic pathways are involved in the regulation of orofacial blood flow. The effect of atropin (1 mg, iv.) on blood flow responses in the lower lip, nose and hand during painful tooth stimulation was studied in healthy human subjects (n=8). In all subjects, tooth stimulation caused a long lasting vasodilatation in the lower lip. During stimulation there was a transient elevation in heart rate (HR) and blood pressure (BP) concomitantly with a blood flow decrease in the finger and nose. With atropin, the pain-induced HR and BP elevations and blood flow reductions in the nose and finger were decreased. However, the pain-induced blood flow increase in the lip was not changed. This study indicates that the tooth stimulation-induced vasodilatation in the lip is not based on parasympathetic cholinergic mechanisms.

Atropine↗
PubMed2001

Changes in tooth pulpal detection and pain thresholds in relation to jaw movement in man.

The effect of jaw movements on pulpal sensory thresholds to electrical stimulation was studied in healthy humans. The movements consisted of repeated jaw opening and closing at two different frequencies (1 and 3 s(-1)). The detection/perception and pain thresholds of an upper or lower central incisor were determined by stimulation with monopolar constant current pulses at two different durations (0.5 and 5.0 ms). In the absence of jaw movement, the control (baseline) pain threshold was significantly higher than the detection threshold, and both thresholds were significantly decreased with an increase of the stimulus pulse duration. During jaw movement, pulpal detection and pain thresholds were significantly elevated, independent of the duration of the stimulus pulse. The jaw movement-related increase in detection thresholds was significantly dependent on the rate of cyclical jaw movements and on the site of stimulation. An increase in pulpal sensory thresholds was observed with stimulation of the lower incisor only; there was no change in thresholds for the upper incisor. Pulpal detection thresholds were significantly more elevated during jaw movement than pulpal pain thresholds. The results indicate that the reduction in pulpal sensitivity is related to the jaw movements. The effect of jaw movement on pulpal detection thresholds was segmentally restricted. In contrast, modulation of the pulpal pain thresholds was considerably weaker. The jaw movement-related suppression of pulpal sensitivity may be explained by activation of segmental afferent-induced inhibition, corollary efferent barrage from motor to sensory areas, or a combination of both.

Adult↗
PubMed2001

The importance of stimulus site and intensity in differences of pain-induced vascular reflexes in human orofacial regions.

Studies in anaesthetized animals have indicated that noxious stimulation may produce marked blood flow changes in various orofacial structures, but the influence of painful stimulation on the blood flow regulation of the orofacial area of humans has been studied only to a limited extent. The purpose of this investigation was to study whether there are differences in temporal and spatial patterns of pain-induced vasoactive reflexes between various orofacial regions and hand in healthy human volunteers. Dynamic changes in blood flow in various orofacial regions elicited by painful stimulation of the tooth and finger were measured by means of Laser Doppler imaging (LDI) and computer-assisted infrared thermography (IRT). Blood flow of the finger was recorded by laser Doppler flowmetry (LDF) and plethysmography (PLET). During both stimulus paradigms there was a transient elevation in heart rate (HR) and blood pressure (BP). At the same time there was a significant blood flow decrease in the finger (LDF, PLET) and in the nose (LDI, IRT). In contrast to tooth stimulation, finger stimulation caused a more marked blood flow reduction in the finger. Only high intensity tooth stimulation, but not finger stimulation, caused a long-lasting vasodilatation both in lower and upper lip. The blood flow changes in the lips were not correlated with changes in systemic blood pressure or heart rate. In the cheek, there were no marked flow changes during either finger or tooth stimulation. These data indicate that painful tooth (regional) stimulation, but not finger (remote) stimulation, can induce a long-lasting vasodilatation in parts of orofacial tissues which cannot be explained by changes in central cardiovascular parameters. This tooth-stimulation-induced blood flow increase supports the hypothesis of a special vasodilator reflex mechanism in the orofacial area. Furthermore, tooth-stimulation-induced vasoconstriction in the nose and dilatation in the lips indicate that separate vasoactive reflex mechanisms may exist for different orofacial regions.

Adult↗
PubMed1999

Altered control of submaximal bite force during bruxism in humans.

The control of bite force during varying submaximal loads was examined in patients suffering from bruxism compared to healthy humans not showing these symptoms. The subjects raised a bar (preload) with their incisor teeth and held it between their upper and lower incisors using the minimal bite force required to keep the bar in a horizontal position. Further loading was added during the preload phase. A sham load was also used. Depending on the session, the teeth were loaded by the experimenter or the subject and in one session the subject did not see the load (no visual feedback). The bite force was measured continuously using a calibrated force transducer. In all the subjects, the bite force increased with increasing load. Following the addition of the load, the level of the tonic bite force was reached rapidly with no marked overshoot. The patients with bruxism used significantly higher bite forces to hold the submaximal loads compared to the control subjects. In the control subjects, the holding forces for each submaximal load were identical in the men and the women and were independent of subject maximal bite force. Sham loading evoked no marked responses in biting force. Whether the subject or the experimenter added the load or whether the subject had visual feedback or not were not significant factors in determining the level of bite force. The results indicated that the patients with bruxism used excessively large biting forces for each given submaximal load. This study showed no evidence that the inappropriate control of bite force by patients with bruxism was due to an abnormality in the higher cortical circuits that regulates the function of trigeminal motoneurons in the brainstem. This was shown by a lack of abnormality in coordination of voluntary hand movement with biting force, a lack of abnormal anticipation response to a sham load and a lack of any effect of visual feedback. The results were in line with the hypothesis that afferent input from oral (periodontal or masticatory muscle) tissues does not provide an appropriate control of motor command in bruxism.

Adult↗
PubMed1999

Features of cortically evoked swallowing in the awake primate (Macaca fascicularis).

Although the cerebral cortex has been implicated in the control of swallowing, the output organization of the cortical swallowing representation, and features of cortically evoked swallowing, remain unclear. The present study defined the output features of the primate "cortical swallowing representation" with intracortical microstimulation (ICMS) applied within the lateral sensorimotor cortex. In four hemispheres of two awake monkeys, microelectrode penetrations were made at </=1-mm intervals, initially within the face primary motor cortex (face-MI), and subsequently within the cortical regions immediately rostral, lateral, and caudal to MI. Two ICMS pulse trains [35-ms train, 0.2-ms pulses at 333 Hz, </=30 microA (short train stimulus, T/S); 3- to 4-s train, 0.2-ms pulses at 50 Hz, </=60 microA (continuous stimulus, C/S)] were applied at </=500-micron intervals along each microelectrode penetration to a depth of 8-10 mm, and electromyographic (EMG) activity was recorded simultaneously from various orofacial and laryngeal muscles. Evoked orofacial movements, including swallowing, were verified by EMG analysis, and T/S and C/S movement thresholds were determined. Effects of varying ICMS intensity on swallow-related EMG properties were examined by applying suprathreshold C/S at selected intracortical sites. EMG patterns of swallows evoked from various cortical regions were compared with those of natural swallows recorded as the monkeys swallowed liquid and solid material. Results indicated that swallowing was evoked by C/S at approximately 20% of 1,569 intracortical sites where ICMS elicited an orofacial motor response in both hemispheres of the two monkeys, typically at C/S intensities </=30 microA. In contrast, swallowing was not evoked by T/S in either monkey. Swallowing was evoked from four cortical regions: the ICMS-defined face-MI, the face primary somatosensory cortex (face-SI), the region lateral and anterior to face-MI corresponding to the cortical masticatory area (CMA), and an area >5 mm deep to the cortical surface corresponding to both the white matter underlying the CMA and the frontal operculum; EMG patterns of swallows elicited from these four cortical regions showed some statistically significant differences. Whereas swallowing ONLY was evoked at some sites, particularly within the deep cortical area, swallowing was more frequently evoked together with other orofacial responses including rhythmic jaw movements. Increasing ICMS intensity increased the magnitude, and decreased the latency, of the swallow-related EMG burst in the genioglossus muscle at some sites. These findings suggest that a number of distinct cortical foci may participate in the initiation and modulation of the swallowing synergy as well as in integrating the swallow within the masticatory sequence.

Animals↗
PubMed1999

Masticatory force and function in patients with hemispheric brain infarction and hemiplegia.

Recent functional animal studies have reported that the motor control of masticatory muscle function is bilaterally guided by both hemispheres, which may fundamentally differ from the cortical control of limb muscle function. In this study, we investigated whether unilateral cortical brain infarction induces different impairments in masticatory and upper limb motor performance. Evidence of the importance of both hemispheres in controlling masticatory movements would be greater if the masticatory function were shown to be unimpaired in patients with severe hemiplegia. The masticatory function of 16 patients with severe hemiparesis caused by brain infarction in the region of the middle cerebral artery was studied by means of interview, clinical examination, and bite-force measurements. Finger-thumb grip-force measurements and clinical examination of the upper limbs were also performed for evaluation of the effect of infarction on upper limb motor function. Localization of the infarction was confirmed with computer tomography and magnetic resonance imaging. The Scandinavian Stroke Scale demonstrated that each patient had a major unilateral cortical infarction which had caused a marked handicap with a serious impairment of upper limb function on the contralateral side. The clinical examination revealed no major signs of temporomandibular disorders, and the masticatory muscles, when examined by palpation, contracted symmetrically. None of the patients with unilateral brain infarction showed any differences in bite forces between the healthy and paralyzed sides. These results indicate that, in hemiparetic patients, great differences may exist between the motor performances of the masticatory and upper limb muscles. The present investigation clinically illustrates the importance of both hemispheres in the control of masticatory function and movements.

Adult↗
PubMed1998

Different effects of physical exercise on cold pain sensitivity in fighter pilots with and without the history of acute in-flight neck pain attacks.

PURPOSE: The cold pain sensitivity in fighter pilots was studied by using a cold pressor test. METHODS: The pilots were divided into two groups: one group consisting of eight pilots (N = 8) who had experienced several acute in-flight neck pain attacks, and the control group (N = 8) who had not experienced these pain conditions under similar work and environment conditions. In each pilot cold pain thresholds and pain and unpleasantness responses to suprathreshold cold stimulations were recorded during repeated tests. The ratings of pain and unpleasantness responses to cold stimulations were evaluated by visual analog scales (VAS). The effect of exercise on cold pain sensitivity was tested in a separate experiment. Exercise was performed on a cycle ergometer at different workload levels (50-200 W). RESULTS: In the control conditions (resting measures) of this study during repeated cold pressor tests, the average pain thresholds and pain or unpleasantness responses to suprathreshold cold stimulation were not different between groups. Physical exercise increased pain thresholds (P < 0.001) in pilots with a history of neck pain attacks but not in control group. Exercise induced a significant decrease in pain responses and unpleasantness responses to suprathreshold stimulation in both groups. This exercise effect was more marked both in pain intensity (P < 0.05) and unpleasantness responses (P < 0.01) in pilots with a history of neck pain attacks. Moreover, exercise more markedly (P < 0.05) decreased unpleasantness than pain intensity responses in both groups of pilots. CONCLUSIONS: The results suggest that exercise stress-related analgesia mechanisms may be enhanced in pilots with a history of acute in-flight neck pain attacks. Moreover, sensory and nonsensory aspects of pain experience may be differentially influenced by exercise stress.

Adult↗
PubMed1997

A comparative prospective clinical study of two single-tooth implants: a preliminary report of 102 implants.

STATEMENT OF PROBLEM: Treatment of tooth loss in the anterior maxilla can involve difficult functional, esthetic, and psychologic problems, especially in young patients with otherwise good dentition. PURPOSE: The purpose of this study was to provide a preliminary comparative evaluation of two implants (ITI and Astra) in single-tooth restorations. MATERIAL AND METHODS: This prospective study of 102 single-tooth replacements with 56 ITI and 46 Astra dental implants was performed in 82 patients at the Finnish Student Health Service Foundation. One Astra implant was lost before loading. The overall survival rate of the implants was 97.8% for Astra implants and 100% for the ITI system. After the initial healing period of at least 6 months, the remaining 101 implants (56 ITI, 45 Astra) were free of periimplant infection and revealed no detectable mobility. Radiographs did not reveal signs of periimplant radiolucencies. All 101 implants received single-tooth crowns. RESULTS: Periimplant parameters and acceptable implant function were examined and demonstrated satisfactory results with preestablished clinical parameters and radiographs at 1 year. During the observation time the mean marginal bone loss was 0.13 mm with Astra implants and 0.11 mm with ITI implants. Subjectively all patients were satisfied with their single-tooth restorations supported by either ITI or Astra dental implants. CONCLUSION: The favorable results of this short-term study support the application of the two implant systems for single-tooth restorations, especially in the anterior region of the maxilla.

Adolescent↗
PubMed1997

Functional properties of neurons in the primate tongue primary motor cortex during swallowing.

Recent studies conducted in our laboratory have suggested that the tongue primary motor cortex (i.e., tongue-MI) plays a critical role in the control of voluntary tongue movements in the primate. However, the possible involvement of tongue-MI in semiautomatic tongue movements, such as those in swallowing, remains unknown. Therefore the present study was undertaken in attempts to address whether tongue-MI plays a role in the semiautomatic tongue movements produced during swallowing. Extracellular single neuron recordings were obtained from tongue-MI, defined by intracortical microstimulation (ICMS), in two awake monkeys as they performed three types of swallowing (swallowing of a juice reward after successful tongue task performance, nontask-related swallowing of a liquid bolus, and nontask-related swallowing of a solid bolus) as well as a trained tongue-protrusion task. Electromyographic activity was recorded simultaneously from various orofacial and laryngeal muscles. In addition, the afferent input to each tongue-MI neuron and ICMS-evoked motor output characteristics at each neuronal recording site were determined. Neurons were considered to show swallow and/or tongue-protrusion task-related activity if a statistically significant difference in firing rate was seen in association with these behaviors compared with that observed during a control pretrial period. Of a total of 80 neurons recorded along 40 microelectrode penetrations in the ICMS-defined tongue-MI, 69% showed significant alterations of activity in relation to the swallowing of a juice reward, whereas 66% exhibited significant modulations of firing in association with performance of the trained tongue-protrusion task. Moreover, 48% showed significant alterations of firing in relation to both swallowing and the tongue-protrusion task. These findings suggest that the region of cortex involved in swallowing includes MI and that tongue-MI may play a role in the regulation of semiautomatic tongue movement, in addition to trained motor behavior. Swallow-related tongue-MI neurons exhibited a variety of swallow-related activity patterns and were distributed throughout the ICMS-defined tongue-MI at sites where ICMS evoked a variety of types of tongue movements. These findings are consistent with the view that multiple efferent zones for the production of tongue movements are activated in swallowing. Many swallow-related tongue-MI neurons had an orofacial mechanoreceptive field, particularly on the tongue dorsum, supporting the view that afferent inputs may be involved in the regulation of the swallowing synergy.

Animals↗
PubMed1997

Differential effects of noxious conditioning stimulation of the cheek by capsaicin on human sensory and inhibitory masseter reflex responses evoked by tooth pulp stimulation.

In this study, we investigated whether selective activation of nociceptive primary afferent fibers by capsaicin would induce modulations on tooth-pulp-evoked sensory or inhibitory masseter reflex responses in healthy human subjects. The contribution of central N-methyl-D-aspartate (NMDA) receptor mechanisms in capsaicin-induced effects on sensory or reflex responses was evaluated by dextromethorphan, an NMDA-receptor antagonist. The inhibitory masseter reflex was evoked by electrical stimulation (constant current, single pulses) of the upper incisor while the subject was biting at 10% of his maximal force. The sensation of the tooth pulp stimulation was evaluated by visual analogue scale (VAS). The magnitude, duration, and the the latency of the reflex were determined by bite force measurements. The inhibitor masseter reflex could be induced by non-painful tooth pulp stimulation, and the inhibition was enhanced as a function of increasing stimulus intensity. Capsaicin (1%) applied topically to the skin of the cheek produced a spontaneous burning pain sensation. During capsaicin treatment, the VAS ratings for the sensation induced by tooth pulp stimulation were significantly reduced, whereas no significant changes were found in the tooth-pulp-induced masseter reflex responses. Double-blind treatment with dextromethorphan at a dose of 100 mg (= the highest does without side-effects) had no effect on sensory or reflex responses. These data indicate that noxious stimulation of the facial skin by capsaicin induces differential effects on tooth-pulp-evoked sensory and inhibitory masseter reflex responses: Sensory responses are strongly attenuated, while masseter reflex responses are not significantly changed. Dextromethorphan at a clinically applicable dose does not influence tooth-pulp-evoked sensory or reflex responses or their modulation by capsaicin. Furthermore, the lack of modulation of the masseter reflex response by capsaicin differs from the capsaicin-induced enhancement of a nocifensive limb flexion reflex described earlier.

Administration, Cutaneous↗
PubMed1994

Blood flow increase in the orofacial area of humans induced by painful stimulation.

The purpose of this study was to investigate if painful stimulation produces blood flow changes in the tooth pulp and the facial skin in humans. Also, we attempted to find out if the possible blood flow changes induced by painful stimulation could be explained by central sympathetic and parasympathetic reflex mechanisms, by an antidromic activation of nociceptive axons (axon reflex), or by a change in central cardiovascular parameters. Laser Doppler flowmeter was used to assess the blood flow changes. Electrical tooth pulp stimulation at painful intensities induced a blood flow increase in the ipsilateral lip adjacent to the stimulus site, and vice versa. Nonpainful stimulation had no effects. Painful thermal stimulation of the upper lip also produced an increase in the blood flow of the ipsilateral upper incisor. The blood flow changes in the lip produced by dental stimulation were not correlated with changes in systemic blood pressure or heart rate. Painful electrical stimulation of the hand did not induce any changes in the pulpal blood flow, whereas painful dental stimulation produced a blood flow decrease in the finger but no change in the contralateral lip or cheek. In monkey experiments a regional block of the central conduction of the inferior alveolar nerve at the level of the mandibular foramen produced varying results: the blood flow increase in the lower incisor produced by noxious thermal stimulation of the ipsilateral lower lip was not abolished in two experiments but was abolished in other two experiments. It is concluded that painful stimulation can induce significant increases in the blood flow of the orofacial regions in humans. This increase is predominantly restricted to the region adjacent to the stimulus site and cannot be explained by changes in the central cardiovascular parameters. Central neuronal reflex mechanisms and an axon reflex may both underlie these blood flow increases.

Adult↗