Svend Kaaber

Sensory and pain thresholds to orofacial argon laser stimulation in patients with chronic burning mouth syndrome

OBJECTIVE Psychophysical assessments of orofacial sensory function were performed in order to investigate neurophysiological aspects of the burning mouth syndrome (BMS). DESIGN Sensory and pain thresholds to brief argon laser stimulation were determined on six test regions, which included the tip of tongue, the lower lip mucosa and skin, the buccal mucosa, the anterior hard palate, and the dorsum of the hand. SETTING The experimental examination was performed at the Pain Clinic Unit at the Royal Dental College. PATIENTS Twenty-three elderly denture-wearing patients diagnosed as suffering from BMS were studied, and a control group included 23 age-, sex-, and denture-matched subjects. The obtained thresholds were compared between groups. RESULTS Sensory thresholds were significantly higher and ratios between pain and sensory thresholds significantly lower in patients with BMS on all the tested regions. Pain thresholds were significantly elevated on the lower lip skin, the anterior hard palate, and the hand in patients with BMS. At sensory threshold level, a faint pinprick perception was often reported by patients with BMS contrary to a perception of warmth described by control subjects. The intraregional variations in sensory and pain thresholds on the hard palate, the lower lip mucosa, and on the skin were similar in both groups, but differences occurred in sensory thresholds on the tongue in patients with BMS. CONCLUSIONS The presence of abnormal prepain perceptions and disturbances in the perception of nonnociceptive and nociceptive thermal stimuli applied on both pain-affected and normal regions suggest a perceptual deficit unrelated to specific pathophysiological mechanisms in BMS. However, it appears that a psychological explanation of BMS should be used cautiously, as the present results suggest alterations in sensory function.

Skin sensitivity to denture base materials in the burning mouth syndrome

The significance of sensitizing compounds in the denture base for the etiology of the burning mouth syndrome (HMS) has been studied in 53 denture‐wearing persons, seven mules and 46 females. Epicutaneous patch tests were performed with standard concentrations of benzoyl peroxide, dibutylphthalate, dimethyl‐p‐toluidine, formaldehyde, hydroquinone, methylmethacrylate, p‐phenylendiamine and with cadmium sulfate, potassium dichromate, cobalt chloride and nickel sulfate. Furthermore, patch testing was performed with filings from the denture mixed with the patients own saliva. In cases with an inflamed oral mucosa, the presence of hyphae of Candida albicans was assessed by a smear technique. Positive skin reactions were observed in 15 persons to dimethyl‐p‐toluidine, hydroquinone, formaldehyde, methylmethacrylate, p‐phenylendiamine, potassium dichromate, cobalt chloride and nickel sulfate, including three cases with reactions to filings from their dentures, and one patient, who after subsequent testing showed skin sensitivity to balsam of Peru. In 12 cases an etiological connection could be traced between the oral symptoms and the denture base, indicating that contact sensitivity to base materials or to allergens and microbial antigens on the denture plate plays a greater role in the pathogenesis of BMS in edentulous persons than previously suggested.

Quantitative determinations of sensory and pain thresholds on human oral mucosa by argon laser stimulation

&NA; High‐energy light from an argon laser was applied to human oral mucosa in order to investigate regional pain sensitivity. Significant regional differences in sensory and pain thresholds were observed between the test sites on the hard and soft palatal mucosa, the buccal mucosa, the tongue, the lower lip, and the skin on the hand. Pain thresholds were lowest on the tip of the tongue and highest on the hard palate. Sensory and pain thresholds were influenced by different stimulus parameters: pulse duration and laser beam diameter. Blackening of the mucosa in regions with high optical reflectance, such as the hard palate, increased light absorption and, hence, reduced both thresholds significantly. Reflectance spectrophotometric measurements indicated that the hard palatal mucosa reflected argon laser light about 1.5 times more than the tip of the tongue. The different threshold values could, in part, be ascribed to different reflectance and absorption properties of the mucosal areas but also indicated substantial regional variation in pain sensitivity of the human oral mucosa. Measurement of laser thresholds is an appropriate and standardized method for investigating sensory differences in human oral mucosa and may be used to study various pain conditions e.g., burning mouth syndrome.

The role of cadmium as a skin sensitizing agent in denture and non‐denture wearers

Positive patch test reactions to cadmium were observed in 8 out of 21 denture wearing persons with burning mouth sensations during 1979 and 1980, and in 13 of 125 consecutive outpatients being routine tested at the Dermatological Department in late 1980 and early 1981, Retesting 17 of these patients after at least 3 months delay with 2.0% cadmium chloride and 2% cadmium sulphate in water showed only 7 with a definite positive reaction. At serial dilution of cadmium sulphate, only 1 person reacted to a 1% aqueous solution. An exposure to cadmium could in 1 case be traced back to a 2‐year period of work in a PVC plant, while in the remaining 6 cases the most probable exposure factor seemed to be chronic heavy cigarette smoking. The observations did not lend support to the pink acrylic denture base material being a relevant cadmium exposure factor.