Automatic stimulus breaker for electric dental pulp tester using pain response.

The pulp test provides a means of examining the vitality of dental pulp using physical or chemical stimulation. During electrical pulp testing, an electrical current stimulates the intradental nerve, which may be painful and stressful to patients. The study involved measurement of the electromyogram (EMG) from the anterior belly of the digastric muscle, finger movement and voice response during electrical pulp testing. The excessive stimulus time from the onset time of response (EMG, voice and finger movement) to the end of the stimulation was obtained. The results indicated that the responses occurred in the order: EMG, finger and voice. Based on these results, an automatic stimulus shut-off circuit was developed using the above-mentioned responses to stimulus during electric pulp testing. Excessive stimulus time was reduced by prompt switching-off of the pulp tester output, 64 ms on average after the first detected response (EMG). Consequently, excessive stimulus times were reduced by 284 and 152 ms on average for the subject and examiner disconnection, respectively, using the developed automatic shut-off circuit. Therefore it was possible to minimise pain and stress by reducing excessive pulp stimulation.

An investigation of language used by children to describe discomfort during dental pulp-testing.

AIM: Studies of the descriptions of pain by children have neglected their linguistic development, therefore estimates of dental pain in children may not be accurate. This study sought (1) to identify words chosen by children to describe dental pain and (2) to establish the effect of linguistic development on that description. SAMPLE: Seventy-eight consecutive children between the ages of 5 and 13 years attending a paediatric dental clinic. METHOD: Each child completed the WORD reading comprehension test. They then underwent a pulp test and a simulated pulp test, administered by a dentist in a counterbalanced order, of a healthy primary canine or permanent incisor, according to the child's age. To describe each test, the children had to (1) select words from a list of 58 read by the experimenter and (2) give ratings on scales representing 'sore' and 'tingly'. RESULTS: Analysis of variance confirmed that the children chose more words for the pulp test than for the simulated test (P < 0.001); the former also elicited higher ratings for 'sore' and 'tingly'. The numbers of words chosen were transformed by a square root constant to ensure a normal distribution. Multiple regression analysis then showed that (1) the better the children's reading comprehension, the fewer words they chose, possibly because they were less inclined to choose unfamiliar words, and (2) the older they were, the more words they chose, possibly because of having more experience of pain. There were similar findings for ratings of 'sore' and 'tingly'. CONCLUSIONS: To assess children's experience of pain (1) they need to be presented with a list of words like the ones in this study, (2) the numbers of words chosen by them would represent the severity of pain, and (3) those numbers need to be adjusted for the children's reading comprehension and age.

Effects of alternating and direct electrical current application on the odontoblastic layer in human teeth: an in vitro study.

AIM: The aim of this study was to investigate the influence of a low intensity alternating current on the odontoblasts and odontoblast layer and compare this with the effects of a direct current. METHODOLOGY: Teeth extracted for orthodontic reasons were immersed in physiological saline stabilized with thymol crystals. Within 1 h of extraction, an alternating or direct current was applied on the crown in the direction of the apex of the tooth for 120-360 s. The current doses were 12, 30, 60, 600, 1800, 3600, 7200, 24,000 and 144,000 microC. The teeth were fixed in Bouin or Baker fluids, the pulps removed, dehydrated and immersed in paraffin, then sectioned, stained with haematoxylin and eosin, and studied under a light microscope. RESULTS: Neither direct nor alternating current, similar to that applied in electrical caries diagnosis caused histological changes in the odontoblasts. CONCLUSIONS: There was no difference between direct and low intensity alternating current in the response of the odontoblast.

Pulpal temperature changes during low-power hard-tissue CO² laser procedures / Mudanças na temperatura pulpar durante procedimentos com laser de co² de baixa intensidade em tecido duro

Thermal insult to pulpal tissue is recognized as a major limitation to the use of lasers for dental hard-tissue procedures. This study examined thermal changes at the level of dental pulp in human molar teeth irradiated with a CO² dental laser using a pulsed mode of operation. Sectioned molar teeth were exposed, in vitro, to CO² laser radiation. The laser parameters were those used clinically for laser desensitization and laser-enhanced fluoride treatment. Fissure regions and root surfaces were irradiated. For settings which might reasonably be used clinically, the temperature rise was not of a magnitude which would be expected to cause pulpal inflammation or necrosis. With regard to thermal properties of tooth structure, times taken to reach the maximum temperature reduced, and times taken to cool to baseline increased with increasing laser exposures

[Cracks in the dental enamel caused by sensitivity testing with CO2 snow and dichloro-difluoromethane--a comparative in vivo study]. / Schmelzsprünge durch die Sensibilitätsprünfung mit CO2-Schnee und Dichlor-difluormethan - eine vergleichende In-vivo-Untersuchung

With the aid of permeating dye and standardized fluorescence UV-photography, the reaction of subjects and enamel to the application of two pulp vitality testing methods (frozen carbon dioxide and Frigen -pellets) was examined. The enamel lamella system, the diffusion of temperature changes through the tooth crown and the thermodynamic pattern of enamel and dentine are described in detail. Structural changes of enamel as well as the subject's reaction times to a cold stimulus during the vitality tests are documented and the data are compared. Frigen caused less enamel changes than did frozen carbon dioxide. The subject's reaction times were similar for both methods. There were no differences between the methods with regard to the number of reopened, extended and newly created enamel fissures. However, the length, width and depth of these fissures proved to be less pronounced for Frigen than for carbon dioxide. Clinical implications of the results are discussed.