Heli Forssell

Role of the dopaminergic system in chronic pain -- a fluorodopa-PET study.

&NA; Recent data from animal experiments suggest an important role for the basal ganglia in the processing and sensorimotor gating of nociceptive information. However, very little is known about their possible participation in human pain. Because of our previous finding of increased excitability of the blink reflex (a brainstem reflex under dopaminergic inhibitory control) in some burning mouth syndrome (BMS) patients, we have studied the dopaminergic function of the striatum (putamen and caudatus) of BMS patients with positron emission tomography (PET). 6‐[18F]fluorodopa (FDOPA) PET scans were done on ten BMS patients and 14 healthy control subjects. The presynaptic dopaminergic function was significantly decreased in the right putamen (20%, P=0.04) of the BMS patients compared to control subjects. On the left side, the FDOPA uptake was decreased by 17% (P=0.08). The mean FDOPA uptake was not significantly changed in the caudate nucleus of the patients. The finding of decreased striatal FDOPA uptake in the putamen supports our previous neurophysiological observations indicating decreased dopaminergic inhibition in BMS patients. The present result provides direct evidence of the involvement of the nigrostriatal dopaminergic system in pain for the first time in a clinical pain condition.

Striatal dopamine D1 and D2 receptors in burning mouth syndrome

&NA; Animal studies have indicated that the nigrostriatal dopaminergic system is involved in central pain modulation. In a recent positron emission tomography (PET) study, we demonstrated presynaptic dysfunction of the nigrostriatal dopaminergic pathway in burning mouth syndrome, which is a chronic pain state. The objective of the present study was to examine striatal dopamine D1 and D2 receptors in these patients. We used 11C‐NNC 756 and 11C‐raclopride to study D1 and D2 receptor binding in a PET study in ten burning mouth patients and 11 healthy controls. Patients underwent a structured psychiatric evaluation and an electrophysiological test for the excitability of the blink reflex. The striatal uptake of 11C‐NNC 756 did not differ between patients and controls. In a voxel‐level analysis, the uptake of 11C‐raclopride was statistically significantly higher in the left putamen in burning mouth patients (corrected P‐value 0.038 at cluster‐level). In the region of interest analysis, the D1/D2 ratio was 7.7% lower in the right putamen (0.64±0.04 vs. 0.69±0.04, P=0.01) and 6.4 % lower in the left putamen (0.65±0.05 vs. 0.70±0.05, P=0.05) when compared to controls. Increased 11C‐raclopride uptake and the subsequent decrease in the D1/D2 ratio may indicate a decline in endogenous dopamine levels in the putamen in burning mouth patients.

Occlusal treatments in temporomandibular disorders: a qualitative systematic review of randomized controlled trials.

Occlusal treatments (occlusal splints and occlusal adjustment) are controversial but widely used treatment methods for temporomandibular disorders (TMD). To investigate whether studies are in agreement with current clinical practices, a systematic review of randomized controlled trials (RCTs) of occlusal treatment studies from the period 1966 to March 1999 was undertaken. Eighteen studies met the inclusion criteria, 14 on splint therapy, and 4 on occlusal adjustment. The trials were scored using the quality scale presented by Antczak et al., 1986a (A.A. Antczak, J. Tang, T.C. Chalmers, Quality assessment of randomized control trials in dental research. I. Methods, J. Periodontal Res. 1986a;21:305-314). The overall quality of the trials was fairly low, the mean quality score was 0.43/1.00 (range 0.12-0.78). The most obvious methodological shortcomings were inadequate blinding, small sample sizes, short follow-up times, great diversity of outcome measures and numerous control treatments, some of unknown effectiveness. Splint therapy was found superior to 3, and comparable to 12 control treatments, and superior or comparable to 4 passive controls, respectively. Occlusal adjustment was found comparable to 2 and inferior to one control treatment and comparable to passive control in one study. Because of the methodological problems, only suggestive conclusions can be drawn. The use of occlusal splints may be of some benefit in the treatment of TMD. Evidence for the use of occlusal adjustment is lacking. There is an obvious need for well designed controlled studies to analyse the current clinical practices.

Abnormalities of the blink reflex in burning mouth syndrome.

&NA; To our knowledge, this is the first report on pain‐related abnormalities of the eye blink reflex (BR) in a clinical pain patient population. The objective of this study was to evaluate the possible neuropathic mechanisms underlying the burning mouth syndrome (BMS), by means of objective electrophysiological examination of the trigemino‐facial system. We studied the BR with stimulation of the supraorbital nerve (SON) with particular emphasis on the occurrence of the pain‐related ultralate R3 components, and the habituation response of the R2 components. The subjects consisted of eleven BMS patients and 10 healthy control subjects. All patients underwent thorough clinical oral and neurological examinations. The motor function of the trigeminal nerve was assessed with a jaw reflex recording, and a needle‐EMG examination of the facial and masticatory muscles was performed in the patients with abnormalities in the BR recordings. The jaw reflexes, the latencies of the BR components, and the needle‐EMG examinations were normal in all patients. As a group, the BMS patients had statistically significantly higher stimulus thresholds for the tactile R1 components of the BR compared with the control subjects. With non‐noxious stimulation, the BMS patients showed more frequently pain‐related R3 components (11/22 SONs) compared with the controls (3/20 SONs). In addition, four BMS patients had abnormal habituation of the R2 components. In two of these patients, the findings were segmental (i.e., unilateral), coinciding with the side of the subjective BM symptoms. The abnormalities of the BR tests appeared to be related to longer disease duration. Our results suggest a possible pathologic involvement of the nervous system in chronic BMS.

Simple bone cyst: Review of the literature and analysis of 23 cases

A retrospective study of 23 simple bone cysts including analysis of clinical, radiographical, histopathological features and follow-up information was made. The age of the patients varied from 8 to 59 years (mean 21.4 years). All lesions were found in the mandible, and 2 of them were radiologically multilocular. A loose connective tissue lining was found histologically in 8 out of 17 cysts with the biopsy specimens available. At follow-up, 2 failures of the primary surgical treatment were noted. The results emphasize that a proper follow-up is required after the treatment of simple bone cyst.

Resolution of oral lichenoid lesions after replacement of amalgam restorations in patients allergic to mercury compounds

The significance of contact allergy in patients with various oral symptoms was studied. Positive patchtest reactions to mercury compounds were found in 21/91 patients. Of these, 18 had lichenoid lesions in oral mucosa in close contact to amalgam fillings, and three patients with contact allergy had neither amalgam fillings in their teeth nor visible oral lesions. Amalgam replacement was carried out in 15/18 symptomatic patients. The fillings were replaced with gold in three cases, composite resin fillings in six, glass ionomer in three and both gold and composite materials in three cases. In 10 patients there was complete replacement and in five it was restricted to the fillings adjacent to the mucosal lesions. After a mean follow‐up period of 3.2 years a complete cure was seen in seven patients, each of whom had had all their fillings changed. A marked improvement occurred in six patients, and there was no change in two.

Changes in Headache After Treatment of Mandibular Dysfunction

To analyse the effect of treatment of mandibular dysfunction on headache, 35 patients with migraine, 20 patients with combination headache and 36 patients with muscle contraction headache were studied in a clinical double-blind trial. Patients in the treatment group received occlusal adjustment and those in the placebo group mock occlusal adjustment. After eight months and four months, respectively, the neurologist evaluated the treatment outcome. The frequency of headache was reduced in 79% and the intensity in 53% of patients suffering from muscle contraction headache or combination headache in whom the adjustment of the dental occlusion had been successfully accomplished. The difference from the placebo group was statistically significant. The decrease in headache frequency as calculated from the headache diaries correlated with the decrease in the index of clinical signs of mandibular dysfunction.

Osteochondroma of the mandibular condyle report of a case and review of the literature

Osteochondroma (osteocartilaginous exostosis) is a rare tumour in the region of the mandibular condyle. Much confusion seems to exist in the literature in differentiating these tumours from condylar chondromas as well as from condylar hyperplasias. A case of condylar osteochondroma with a review of the literature is presented.

Local dental anaesthesia with lidocaine and adrenaline. Effects on plasma catecholamines, heart rate and blood pressure.

5 volunteers took part in this double-blind, cross-over study to evaluate the role of adrenaline 1:80,000 in lidocaine used in dental local anaesthesia on haemodynamics and the concentrations of catecholamines and their metabolites in plasma. The exogenous adrenaline statistically significantly elevated the heart rate (from 66 +/- 7 to 79 +/- 9 bpm), but did not affect systolic or diastolic blood pressure. Plasma adrenaline concentrations were increased more than 10-fold (from 0.02 +/- 0.02 to 1.0 +/- 0.3 nmol/l). We conclude that the adrenaline present in the local anaesthetic is a major source of adrenergic activation during minor oral surgery.

Effect of occlusal adjustment on mandibular dysfunction A double-blind study

A group of headache patients who also had many signs and symptoms of mandibular dysfunction were randomly assigned to treatment and placebo groups. All 48 patients in the treatment group received occlusal adjustment and 19 of them also splint therapy. In the placebo group all 43 patients received mock adjustment. The changes in symptoms and signs of mandibular dysfunction were evaluated after 8 months in the treatment group and after 4 months in the placebo group, in a double-blind design. Placebo treatment and real treatment were equally effective in relieving symptoms of mandibular dysfunction, but there was significantly more reduction in signs of dysfunction in the treatment group than in the placebo group. When tested statistically, this reduction appeared to be independent of the use of splints as an aid to treatment. It can be concluded that the elimination of occlusal disturbances was an effective treatment for mandibular dysfunction.