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PubMed1996

Electromagnetic interference from welding and motors on implantable cardioverter-defibrillators as tested in the electrically hostile work site.

OBJECTIVES: This study was designed to determine the susceptibility of an implanted cardioverter-defibrillator to electromagnetic interference in an electrically hostile work site environment, with the ultimate goal of allowing the patient to return to work. BACKGROUND: Normal operation of an implanted cardioverter-defibrillator depends on reliable sensing of the heart's electrical activity. Consequently, there is concern that external electromagnetic interference from external sources in the work place, especially welding equipment or motor-generator systems, may be sensed and produce inappropriate shocks or abnormal reed switch operation, temporarily suspending detection of ventricular tachycardia or ventricular fibrillation. METHODS: The effects of electromagnetic interference on the operation of one type of implantable cardioverter-defibrillator (Medtronic models 7217 and 7219) was measured by using internal event counter monitoring in 10 patients operating arc welders at up to 900 A or working near 200-hp motors and 1 patient close to a locomotive starter drawing up to 400 A. RESULTS: The electromagnetic interference produced two sources of potential interference on the sensing circuit or reed switch operation, respectively: 1) electrical fields with measured frequencies up to 50 MHz produced by the high currents during welding electrode activation, and 2) magnetic fields produced by the current in the welding electrode and cable. The defibrillator sensitivity was programmed to the highest (most sensitive) value: 0.15 mV (model 7219) or 0.3 mV (model 7217). The ventricular tachycardia and ventricular fibrillation therapies were temporarily turned off but the detection circuits left on. CONCLUSIONS: None of the implanted defibrillators tested were affected by oversensing of the electric field as verified by telemetry from the detection circuits. The magnetic field from 225-A welding current produced a flux density of 1.2 G; this density was not adequate to close the reed switch, which requires approximately 10 G. Our testing at the work site revealed no electrical interference with this type of defibrillator. Patients were allowed to return to work. The following precautions should be observed by the patient: 1) maintain a minimal distance of 2 ft (61 cm) from the welding arc and cables or large motors, 2) do not exceed tested currents with the welding equipment, 3) wear insulated gloves while operating electrical equipment, 4) verify that electrical equipment is properly grounded, and 5) stop welding and leave the work area immediately if a therapy is delivered or a feeling of lightheadedness is experienced.

Defibrillators, Implantable↗
PubMed2004

Electrophysiological characterization of facilitated spinal withdrawal reflex to repetitive electrical stimuli and its modulation by central glutamate receptor in spinal anesthetized rats.

The present study is aimed to systematically investigate wind-up and after-discharge of the spinal withdrawal reflex assessed by recording single motor unit (SMU) electromyographic (EMG) response to different intensities [0.5-1.5xreflex threshold (T)] of repetitive [frequencies (0.5-200 Hz)] transcutaneous electrical stimuli for 5 s. The role of central glutamate receptors in modulation of the withdrawal reflex facilitation was observed and evaluated in order to explore the potential central mechanism. Stimulus intensities below reflex threshold, such as 0.8xT, but not 0.5xT, could by repetition elicit and facilitate withdrawal reflex. The facilitation (wind-up and after-discharge) of the withdrawal reflex is a result of central integration and is increased significantly for increasing stimulus intensity and frequency. Electrical stimuli at 3-5 Hz for 5 s are appropriate to elicit wind-up. In contrast, 10-20 Hz frequencies of electrical stimuli are adequate to evoke the after-discharge. For pharmacological intervention, suprathreshold (1.5xT) repeated (5 Hz) electrically evoked facilitated reflex (wind-up) were apparently depressed by intrathecal (i.t.) administration of MK-801 as well as CNQX (40 nmol/10 microl, respectively). However, wind-up of spinal reflexes evoked by subthreshold (0.8xT) electrical stimuli could only be depressed by the treatment with CNQX, not MK-801. The after-discharge of the withdrawal reflex elicited by 20 Hz electrical stimulation with either 0.8xT or 1.5xT intensity was depressed by i.t. treatment with CNQX. I.t. application of MK-801 only depressed 0.8xT the intensity of electrically evoked after-discharge. In conclusion, for the first time, the present study clearly demonstrates that, following the wind-up phase, the spinal withdrawal reflex pathways continue to fire spontaneously in a stimulus frequency- and intensity-dependent way (temporal and/or spatial summation). This inherited memory and the central non-N-methyl-d-aspartate (non-NMDA) receptor, but not the NMDA receptor, mainly involving pharmacological mechanisms, may play an important role in pathological conditions with spontaneous nociceptive firing. Furthermore, the after-discharge of the spinal reflex may be an important indicator for studies on central sensitization in many pathological pain conditions.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2004

Protein kinase A increases electrical stimulation-induced neuronal nitric oxide release in rat mesenteric artery.

The aim of this study was to analyse the possible influence of cyclic AMP-protein kinase A (cAMP-PKA) activation on neuronal nitric oxide (NO) release induced by electrical field stimulation in mesenteric arteries from Wistar Kyoto (WKY) rats. Western blot experiments demonstrated the expression of neuronal NO synthase (nNOS) in mesenteric artery from WKY rats; however, electrical field stimulation alone did not induce detectable NO release. Preincubation with forskolin allowed NO release induced by electrical field stimulation, which was abolished by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or N(omega)-propil-l-arginine (NPLA), and the PKA inhibitors N-(2-(p-Bromocinnamylamino) ethyl 5-isoquinolinesulfonamide hydrochloride (H-89) or (9R,10S,12S)-2,3,9,10,11, 12-Hexahydro-10-9-methyl-1-oxo-9,12-epoxy-1H-diindolo(1,2,3-fg:3,2,1k)pyrrolo(3,4-l)(1,6) benzodiazocine-10-carboxylic acid hexyl ester (KT-5720). Preincubation with prostacyclin also allowed the NO release induced by electrical field stimulation which was significantly decreased by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or NPLA, and the PKA inhibitors H-89 or KT-5720. The NOS inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) did not modify the vasoconstrictor response induced by electrical field stimulation. However, in the presence of forskolin or prostacyclin, l-NAME increased the vasoconstrictor response to electrical field stimulation. These results indicate that forskolin and prostacyclin allow neuronal NO release induced by electrical field stimulation through a mechanism involving cAMP-PKA activation in rat mesenteric arteries.

Animals↗
PubMed2006

Analysis of behavior-related excitatory inputs to a central pacemaker nucleus in a weakly electric fish.

Gymnotid electric fish explore their environment and communicate with conspecifics by means of rhythmic electric organ discharges. The neural command for each electric organ discharge arises from activity of a medullary pacemaker nucleus composed of two neuronal types: pacemaker and relay cells. During different behaviors as in courtship, exploration and agonistic interactions, these species display specific electric organ discharge frequency and/or waveform modulations. The neural bases of these modulations have been explained in terms of segregation of inputs to pacemaker or relay cells, as well as differential activation of the glutamate receptors of these cells. One of the most conspicuous electric organ discharge frequency modulations in Gymnotus carapo results from the activation of Mauthner cells, a pair of reticulospinal neurons that are involved in the organization of sensory-evoked escape responses in teleost fish. The activation of Mauthner cells in these animals produces a prolonged increase in electric organ discharge rate, whose neural mechanisms involves the activation of both N-methyl-D-aspartate (NMDA) and metabotropic glutamatergic receptors of pacemaker cells. Here we provide evidence which indicates that pacemaker cells are the only cellular target of the synaptic inputs responsible for the Mauthner cell initiated electric organ discharge modulation at the medullary pacemaker nucleus. Additionally, although pacemaker cells express both NMDA and non-NMDA ionotropic receptors, we found that non-NMDA receptors are not involved in this synaptic action which suggests that NMDA and non-NMDA receptor subtypes are not co-localized at the subsynaptic membrane. NMDA receptor activation of pacemaker cells seems to be an efficient neural strategy to produce long-lasting enhancements of the fish sampling capability during Mauthner cell-initiated motor behaviors.

Action Potentials↗
PubMed1998

Braking electric-powered wheelchairs: effect of braking method, seatbelt, and legrests.

OBJECTIVE: To examine the influence of three electric-powered wheelchair braking conditions and four wheelchair seating conditions on electric-powered wheelchair motion and Hybrid II test dummy motion. This study provides quantitative information related to assessing the safety of electric-powered wheelchair driving. DESIGN: Rehabilitation engineering comparison and ANSI/ RESNA standards testing. Convenience sample of eight different electric-powered wheelchairs. Within-chair comparisons were conducted. INTERVENTION: Electric-powered wheelchairs were compared under three braking scenarios (joystick release, joystick reverse, power-off) and four seating conditions (seatbelt and legrests, seatbelt and no legrests, no seatbelt but legrests, no seatbelt and no legrests). SETTING: A rehabilitation engineering center. MAIN OUTCOME MEASURES: The braking distance, braking time, and braking accelerations for electric-powered wheelchairs during three braking scenarios; trunk motion, head motion, and trunk angular acceleration during three braking scenarios and four seating conditions; and number of falls from the wheelchairs for three braking scenarios and four seating conditions. RESULTS: Significant differences (p < .05) were found in braking distance, braking time, and braking acceleration when comparing the joystick release and joystick reverse scenarios with the power-off scenario. The mean braking distance was shortest with the power-off braking scenario (.89m), whereas it was longest when the joystick was released (1.66m). Significant differences (p < .05) in head displacement and trunk angular displacement were observed among braking conditions and between seating conditions. There were also significant differences (p = .0011) among braking conditions for maximum trunk angular acceleration. The Hybrid II test dummy fell from the wheelchairs with highest frequency when there were no legrests and no seatbelt used. CONCLUSION: The results of this study indicate that use of a seatbelt when driving an electric-powered wheelchair reduces the risk of falling from a wheelchair. Furthermore, the use of legrests can reduce the risk of injury to the wheelchair driver. This study shows that the most abrupt braking occurs when deactivating the power switch.

Accidental Falls↗
PubMed2001

Nicotinic receptors involved in gastric noradrenaline release evoked by electrical stimulation of the splanchnic nerve in rats.

In the present experiment, we tried to compare the functional nicotinic receptors activated by electrical stimulation of the greater splanchnic nerve (containing preganglionic sympathetic nerves) to those activated by (-)-nicotine, using the isolated rat stomach. The stomach was perfused with Krebs-Ringer solution and endogenous noradrenaline released into the perfusate was electrochemically measured using high-performance liquid chromatography. The release of noradrenaline evoked by repeated application of 30 mM (-)-nicotine rapidly declined. However, the release of noradrenaline evoked by electrical stimulation of the splanchnic nerve at 2.5 Hz was not disturbed by the appearance of tachyphylaxis for (-)-nicotine. The (-)-nicotine-induced release of noradrenaline was abolished by diltiazem, but this reagent had no effect on the electrically evoked release of noradrenaline. The electrically evoked release of noradrenaline was not influenced by atropine, but was reduced to approximately 50% by hexamethonium. This electrically evoked release of noradrenaline was not influenced by alpha-bungarotoxin, alpha-conotoxin ImI (blockers of alpha 7 nicotinic receptors) or dihydro-beta-erythroidine (a blocker of alpha 4 beta 2 nicotinic receptors), but was reduced to about 50% by mecamylamine (a blocker of alpha 3 beta 4 nicotinic receptors). The (-)-nicotine-induced release of noradrenaline has already been shown to be partially blocked by dihydro-beta-erythroidine and to be abolished by mecamylamine as shown by Yokotani et al. [Eur. J. Pharmacol. 402 (2000) 223.]. These results suggest that the gastric release of noradrenaline in response to electrical stimulation of the greater splanchnic nerve is mediated by cholinergic (probably ganglionic alpha 3 beta 4 nicotinic receptor-mediated) and non-cholinergic mechanisms in rats. However, the functional nicotinic receptor activated by electrical stimulation of the splanchnic nerve seems to be different in character from that activated by (-)-nicotine.

Animals↗
PubMed2003

Deviation from Ohm's law in electric field assisted capillary liquid chromatography.

Earlier studies of electric field assisted LC (EF-LC) have shown that the effect on charged analytes of the application of an electric field over a capillary LC column is relatively small. Charged analytes can only be affected by the electric field while present in the mobile phase, which makes the effective time for influence of the electric field t(0) independent of retention time. Because the charged analytes only can be affected for a short time the electric field strength ought to be high in order to increase the impact of the electric field on the separation. We have, however, found that only a relatively low electric field strength can be used in EF-LC when pressure is used as main driving force. The useful field strength was limited by a dramatic increase in the current. This increase in current was found to origin from an increased concentration of buffer ions that have an electrophoretic mobility towards the pumped flow.

Chromatography, High Pressure Liquid↗
PubMed2003

Application of electric field stimulation for investigations of human placental blood vessels.

OBJECTIVE: To test electric field stimulation on human placental vessels. METHODS: The effects of electric field stimulation on placental vessels were examined in an isometric myograph. RESULTS: Electric field stimulation induced contractions in human placental blood vessels in vitro under isometric conditions when bubbling carbogen through the organ bath. After reaching half-maximal contractions, the vessel rings showed spontaneous relaxation. Pretreatment with verapamil (10(-6) mol/L) or nickel (Ni(2+)) (2 mmol/L) inhibited the contractions to a magnitude of 63.81% +/- 7.69% and 88.36% +/- 12.17% (mean +/- standard error of the mean), respectively. In calcium (Ca(2+))-free medium after combined cyclopiazonic acid (10(-5) mol/L) and Ni(2+) treatment, it was not possible to elicit contractions with electric field stimulation. Bubbling through physiologic in utero hypoxic gases enhanced the contractile responses of the human placental vessel rings to electric field stimulation. The spontaneous relaxation of the veins was not altered, but those of the arteries were reduced to zero. Testing the same gases on mesenteric arteries of rats had an opposite effect concerning contractility. Sodium nitrite decreased the contractions of the placental vessel rings, but the efficacy was decreased by the in utero gases. CONCLUSION: Electric field stimulation has a direct, non-neurogenic contractile effect on isolated placental vessels, which mainly depends on the influx of extracellular Ca(2+) and on a mechanism independent of intracellular Ca(2+) concentration elevation. Physiologic hypoxia has a stimulatory effect on the contractility of human placental vessels, therefore in utero gases should be used instead of carbogen gas; and electric field stimulation is a suitable method for the investigation of the direct effects of pharmacologic agents on human placental vessels.

Adult↗
PubMed1999

Inactivation of Listeria innocua in liquid whole egg by pulsed electric fields and nisin.

Consumer demand for fresh-like products with little or no degradation of nutritional and organoleptic properties has led to the study of new technologies in food preservation. Pulsed electric fields (PEF) is a nonthermal preservation method used to inactivate microorganisms mainly in liquid foods. Microorganisms in the presence of PEF suffer cell membrane damage. Nisin is a natural antimicrobial known to disrupt cell membrane integrity. Thus the combination of PEF and nisin represents a hurdle for the survival of Listeria innocua in liquid whole egg (LWE). L. innocua suspended in LWE was subjected to two different treatments: PEF and PEF followed by exposure to nisin. The selected frequency and pulse duration for PEF was 3.5 Hz and 2 micros, respectively. Electric field intensities of 30, 40 and 50 kV/cm were used. The number of pulses applied to the LWE was 10.6, 21.3 and 32. The highest extent of microbial inactivation with PEF was 3.5 log cycles (U) for an electric field intensity of 50 kV/cm and 32 pulses. Treatment of LWE by PEF was conducted at low temperatures, 36 degrees C being the highest. Exposure of L. innocua to nisin following the PEF treatment exhibited an additive effect on the inactivation of the microorganism. Moreover, a synergistic effect was observed as the electric field intensity, number of pulses and nisin concentration increased. L. innocua exposed to 10 IU nisin/ml after PEF exhibited a decrease in population of 4.1 U for an electric field intensity of 50 kV/cm and 32 pulses. Exposure of L. innocua to 100 IU nisin/ml following PEF resulted in 5.5 U for an electric field intensity of 50 kV/cm and 32 pulses. The model developed for the inactivation of L. innocua by PEF and followed by exposure to nisin proved to be accurate (p = 0.05) when used to model the inactivation of the microorganism by PEF in LWE with 1.2 or 37 IU nisin/ml. The presence of 37 IU nisin/ml in LWE during the PEF treatment for an electric field intensity of 50 kV/cm and 32 pulses resulted in a decrease in the population of L. innocua of 4.4 U.

Anti-Bacterial Agents↗
PubMed2001

Sensitivity of leachate and fine contents on electrical resistivity variations of sandy soils.

Laboratory pilot tests were performed to investigate the relationship between electrical resistivity and contaminated soil properties. Three different sandy soils and leachate collected from one of the industrial waste landfill sites in Korea were mixed to simulate contaminated soil conditions. The values of electrical resistivity of the soils were measured using laboratory scaled resistivity cone penetrometer probe. In the experiments, electrical resistivity was observed in terms of water content, unit weight, saturation degree of the soils, and leachate concentration. The experimental results show that the electrical resistivity of the sandy soils depends largely on the water content and electrical properties of pore water rather than unit weight and types of soils. The amount of fines can have significant effect on electrical properties of soils. Direct correlation with contamination in such soils may not be valid here. The results suggest that the electrical resistivity measurement is well suited and applicable for monitoring and delineation of contaminants in the subsurface.

Electricity↗
PubMed2003

C-Fos immunoreactivity mapping of the auditory system after electrical stimulation of the cochlear nerve in rats.

The aim of this study was to establish the use of c-Fos immunoreactivity as a marker for functional mapping in the auditory system in response to direct electrical stimulation of the cochlear nerve in the cerebellopontine angle. In rats the cochlear nerve was electrically stimulated with a biphasic current (120-250 microA, 5 Hz) for 30 min using a bipolar concentric Tungsten electrode. Bilateral cochlectomy was performed in a control group in order to investigate basal expression of c-Fos in the auditory brainstem nuclei. The response of auditory brainstem nuclei to electrical stimulation and the completeness of cochlear ablations were electrophysiologically verified. After the experiments, the animals were prepared for cryotomy and c-Fos immunohistochemistry. The results were morphologically analyzed and statistically compared among groups. In anesthetized animals with unilateral electrical stimulation of the cochlear nerve increased expression of c-Fos was detected in the ipsilateral ventral (VCN) and bilateral dorsal cochlear nucleus (DCN), whereas the VCN of the contralateral side revealed only few immunoreactive cells. In animals with bilateral cochlear ablation the number of c-Fos reactive cell nuclei representing basal expression was generally low in the VCN and DCN of both sides. Our data show that electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in the cochlear nucleus. It also confirms bilateral connections between the cochlear nuclei. These experimental results suggest that c-Fos immunoreactivity mapping provides a powerful tool for functional investigations on the cellular level after direct electrical stimulation of the cochlear nerve. Future functional studies analyzing the effect of electrical stimulation of the central auditory system as performed by auditory brainstem implants could be investigated in detail by mapping c-Fos expression on cellular level.

Animals↗
PubMed1996

Pitch comparisons of acoustically and electrically evoked auditory sensations.

Cochlear implant users with some residual hearing in the non-implanted ear compared the pitch sensations produced by acoustic pure tones and pulsatile electric stimuli. Pitch comparisons were obtained for pure tones and electrical stimuli presented at different positions (electrodes) in the scala tympani, keeping the electric pulse rate fixed at 100, 250, or 800 pps. Similarly, pitch comparisons were obtained for electrical stimuli with variable pulse rates presented to two fixed electrode positions (apical and basal) in the cochlea. Both electrode position and pulse rate influenced the perceived pitch of the electrical signal and 'matched' electric and acoustic signals were found over a wide range of frequencies. There was a large variation between listeners. For some stimuli, listeners had difficulty in deciding whether the acoustic or electric stimulus was higher in pitch. Despite the variability, consistent trends were obtained from the data: higher frequencies tended to be matched by more basal electrodes for all pulse rates. Higher frequencies tended to be matched by higher pulse rates for both electrode positions. The electrode positions that 'matched' pure tones were more basal than predicted from the characteristic frequency coordinates of the basilar membrane in a normal human cochlea.

Acoustic Stimulation↗
PubMed1997

Acoustic and electric forward-masking of the auditory nerve compound action potential: evidence for linearity of electro-mechanical transduction.

We investigated electro-mechanical transduction within the cochlea by comparing masking of the auditory nerve compound action potential (CAP) by acoustical and electrical maskers. Forward-masking of the CAP reflects the response to the masker of the cochlear location tuned to the probe. Electrical stimulation was delivered through bipolar stimulating electrodes within the basal turn of the scala tympani. The growth of masking of high-frequency probes which excite cochlear locations close to the stimulating electrodes was similar for both acoustic and electrical maskers, suggesting a linear transduction of electrical energy to mechanical energy. Exposure to intense acoustic stimulation caused an equal loss of sensitivity to acoustic and electrical maskers. Masking of lower-frequency probes by electrical maskers increased rapidly with masker current, suggesting the direct electrical stimulation of neural elements. This masking was reduced by the administration of strychnine suggesting a contribution by the efferents towards masking of these low-frequency probes.

Acoustic Stimulation↗
PubMedDate not supplied

Eleven-year-old male with high-voltage electrical injury and premature ventricular contractions.

We present a case of a boy with potential high-voltage electrical injury. The patient sustained electrical injuries after his kite became entangled in a high-power electrical line. He presented to the emergency department with minor external electrical burns and frequent premature ventricular contractions (PVCs). The patient's clinical course is outlined. A discussion of the epidemiology of high-voltage electrical injury in children and the clinical management of electrical-injury-induced cardiac complications is provided. Although cardiac abnormalities are found in a significant proportion of high-voltage electrical injuries, the vast majority are evident within 12 h, resolve spontaneously within a few days, and cause little or no long-term sequelae. A small proportion of normal children have clinically benign PVCs.

Child↗
PubMedDate not supplied

Neuroethology and life history adaptations of the elasmobranch electric sense.

The electric sense of elasmobranch fishes (sharks and rays) is an important sensory modality known to mediate the detection of bioelectric stimuli. Although the best known function for the use of the elasmobranch electric sense is prey detection, relatively few studies have investigated other possible biological functions. Here, we review recent studies that demonstrate the elasmobranch electrosensory system functions in a wide number of behavioral contexts including social, reproductive and anti-predator behaviors. Recent work on non-electrogenic stingrays demonstrates that the electric sense is used during reproduction and courtship for conspecific detection and localization. Electrogenic skates may use their electrosensory encoding capabilities and electric organ discharges for communication during social and reproductive interactions. The electric sense may also be used to detect and avoid predators during early life history stages in many elasmobranch species. Embryonic clearnose skates demonstrate a ventilatory freeze response when a weak low-frequency electric field is imposed upon the egg capsule. Peak frequency sensitivity of the peripheral electrosensory system in embryonic skates matches the low frequencies of phasic electric stimuli produced by natural fish egg-predators. Neurophysiology experiments reveal that electrosensory tuning changes across the life history of a species and also seasonally due to steroid hormone changes during the reproductive season. We argue that the ontogenetic and seasonal variation in electrosensory tuning represent an adaptive electrosensory plasticity that may be common to many elasmobranchs to enhance an individual's fitness throughout its life history.

Adaptation, Biological↗
PubMed1997

Efficacy of electrical stimulation at frequencies higher than basal rate in canine stomach.

The optimum frequency for electrically stimulating motility in the stomach is still in question. Some studies of gastric electrical stimulation (GES) at near physiologic frequencies have reported gastric electrical entrainment but with little efficacy in improving motility. In this study we examined the effectiveness of electrical stimulation at a broad range of frequencies in entraining gastric electrical activity (GEA) and eliciting contractions in a canine model. The stomachs of six dogs, each implanted with four pairs of stainless steel electrodes and two strain gauges were stimulated at frequencies ranging from 3 to 30 cycles/min. GEA and contractions were monitored before and during electrical stimulation. The ability of GES at different frequencies to reverse the effect of glucagon was also investigated. GEA was entrained in most animals at frequencies close to the intrinsic rate as well as at four to five times the intrinsic rate. At other stimulation frequencies, the recorded electrical control activity either remained unchanged, uncoupled, or became dysrhythmic. Contractile response to stimulation at four to five times the intrinsic rate were significantly higher than those at frequencies close to the intrinsic rate (P < 0.05). GES did not alter the effect of glucagon. Stimulation at a frequency of four times the basal rate of 5/min elicited the largest motility index in dogs. Stimulation at frequencies much higher than the physiologic rate warrants further study as a possible optimum range for GES.

Animals↗
PubMed2001

Plaque removal with the uninstructed use of electric toothbrushes: comparison with a manual brush and toothpaste slurry.

BACKGROUND: Individuals purchasing electric toothbrushes for the 1st time will mostly only have the manufacturer's instructional leaflet for information of usage. AIMS: This study was designed to simulate the 1st-time purchase and early use of an electric toothbrush with the aim of comparing plaque removal with a manual toothbrush. Secondary aims were to assess chemical plaque removal effects of a toothpaste slurry and to compare between 2 electric brushes which differed only in head speed. METHODS: A group of 16 dentate subjects participated in this single-examiner blind, randomised, crossover design balanced for residual effects. Subjects had "average" oral hygiene and had never used an electric toothbrush previously. 7 days prior to the study, all subjects received the slower oscillating rotating toothbrush under test to use at home as they wished. The test treatments were brushing with 2 oscillating rotating electric toothbrushes, a manual toothbrush and a rinse with a toothpaste slurry (3 g/10 ml water). On day 1 of each study period, subjects were rendered plaque-free, suspended oral hygiene and returned on day 5. Plaque was scored at baseline by index and area and after 30 s, 30 s (total 60 s) and 60 s (total 120 s) of the cleaning treatments. Washout periods were at least 2 1/2 days. RESULTS: Highly significant treatment differences were found between the 4 treatments because the toothpaste slurry was totally without effect. Analyses between the 3 brush treatments overall revealed no consistent significant differences. The data suggest that in the early days of electric toothbrush use, subjects perform no better than using a manual brush. CONCLUSIONS: The present study, taken with results from others showing greater benefits from the use of electric brushes, supports the idea that dental professionals should, where possible, provide advice and instruction in the use of such devices.

Analysis of Variance↗
PubMed2001

Plaque removal characteristics of electric toothbrushes using an in vitro plaque model.

BACKGROUND/AIM: The purpose of the study was to investigate and quantify the efficacy of plaque removal by commercially available electric toothbrushes using an in vitro system based on artificial plaque grown on glass slides. MATERIAL AND METHODS: Artificial plaque based on Streptococcus sanguis and Streptococcus mutans was cultured in a series of phosphate buffer solution, sucrose solution and brain heart infusion on sterile glass slides, for a period of 5 weeks. 7 different electric toothbrushes of current designs were operated in contact with the glass slides under loads of 1 or 2N for 10 s after which image analysis of the brushed slides was undertaken to calculate the absolute and relative areas of removal. RESULTS: The electric toothbrushes showed a larger area of plaque removal as loading force increased from 1 to 2N. The area of biofilm removed also depended on the head design and ranged from 258 mm(2) (1N, Interplak) and 314 mm(2) (2N, Interplak), to 30 mm(2) (1N, Braun 3D), and 148 mm(2) (2N, Blend-a-Dent). The area of biofilm removal was significantly different among all electric toothbrushes at p<0.01 (ANOVA). All electric toothbrushes removed more biofilm than the actual contacting tufted area of the head. CONCLUSION: The artificial plaque model system under different loading conditions showed differences in the absolute area of removal per electric toothbrush and also differences in the relative removal per unit contact bristle area. These differences on operating variables should be considered when evaluating new electric toothbrushes.

Algorithms↗