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PubMed1975

Some thoughts on the perception of ultrasonics by man.

After a short specification of the ultrasonic transmitter device by which the test frequencies of 20,40,60 and 100 kHz could be emitted by means of a transmitter fixed to the forehead of the subject with constant pressure, the mean perception threshold for ultrasonics is described, which had been recorded by using the wide-band noise of the audiometer MA 30. Both curves do not differ considerably so that ultrasonic investigations can be carried out in the presence of working noise without producing wrong measurement results. A comparison of perception between ultrasonic frequencies and audio frequencies in the hearing range showed that ultrasonics produce, independent of the stimulation frequency, the same sensory impression as a sound at a frequency of about 12 or 13 kHz. Applying this method to hard of hearing subjects with noise induced hearing damages and deaf subjects had the following results: 1. Subjects with noise induced hearing damages very early have a raised perception threshold for ultrasonics. There was no correlation between the extent of the auditory threshold (the shift of the threshold) and the perception threshold of ultrasonics. 2. Deaf people almost without exception are not able to perceive ultrasonics. 3. With hard of hearing of the inner ear of different genesis ultrasonic perception is varying. There was no particular raise of the ultrasonic perception threshold with hereditary hard of hearing of the inner ear. 4. On the basis of the results the question is discussed in which section of the auditory system ultrasonic perception occurs. In the opinion of the authors the origin of perception might be in the organ of Corti itself. An unambiguous proof, however, could not be found so far. At present the procedure of investigation does not yet allow an application in practical diagnostics of ear specialists.

Adolescent↗
PubMed1998

Rat pup ultrasonic vocalization: effects of benzodiazepine receptor ligands.

The involvement of the GABA(A)-benzodiazepine receptor complex in rat pup ultrasonic vocalisations was studied by testing benzodiazepine receptor ligands with varying intrinsic activity and selectivity for benzodiazepine subtype receptors. Ultrasonic vocalisations were recorded under two temperature conditions (37 degrees C and 18 degrees C), presumably reflecting a low and high stress state. The latency to the negative geotaxis response, a measure of motor coordination and the rectal temperature were determined to assess putative side effects of drugs. The full, non-selective benzodiazepine receptor agonists diazepam, chlordiazepoxide, alprazolam and oxazepam suppressed ultrasonic vocalisations both at 37 degrees C and 18 degrees C conditions, although more efficaciously at 37 degrees C. The partial, non-selective benzodiazepine receptor agonist bretazenil and the partial benzodiazepine, selective receptor agonist alpidem significantly reduced ultrasonic vocalisations at 37 degrees C, but not at 18 degrees C. The full benzodiazepine, selective receptor agonist zolpidem behaved like other full, non-selective benzodiazepine receptor agonists by reducing ultrasonic vocalisations under both high and low temperature. The effects of zolpidem indicate that activation of benzodiazepine, receptors alone already suffices to suppress ultrasonic vocalisations. The non-selective, benzodiazepine receptor antagonist flumazenil and the partial, non-selective benzodiazepine receptor inverse agonist FG 7142 (N'-methyl-beta-carboline-3-carboxamide) and the full, non-selective benzodiazepine receptor inverse agonist DMCM (6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate) had no significant effect on ultrasonic vocalisations under both temperature conditions. The involvement of benzodiazepine receptors in rat pup ultrasonic vocalisations (37 degrees C-condition) was confirmed by antagonism of the ultrasonic vocalisations reducing effects of chlordiazepoxide by flumazenil (1 or 3 mg/kg). Using the rat pup ultrasonic vocalisations paradigm under 18 degrees C and 37 degrees C conditions combined with measurements of negative geotaxis-latencies and rectal temperatures it is possible to (1) distinguish benzodiazepine receptor agonists from other anxiolytics because of dissimilar dose response curves at 37 degrees C and 18 degrees C, (2) differentiate partial from full receptor agonists by absence of effects at the 18 degrees C condition, (3) suggest a key role for benzodiazepine, receptors in the modulation of ultrasonic vocalisations. These data contribute to the predictive validity of pup vocalizations as an animal model of anxiety.

Animals↗
PubMed2005

Mechanochemical degradation kinetics of high-density polyethylene melt and its mechanism in the presence of ultrasonic irradiation.

In this paper, the effect of ultrasonic intensity on the degradation of high-density polyethylene (HDPE) melt, degradation mechanism, ultrasonic degradation kinetics of HDPE melt as well as the development of molecular weight distribution of HDPE melt during ultrasonic degradation were studied. In the initial stage, the ultrasonic degradation of HDPE melt shows a random scission process, and the molecular weight distribution broadens. After that, the ultrasonic degradation of HDPE melt shows a nonrandom scission process, and the molecular weight distribution of HDPE melt narrows with ultrasonic irradiation time. The average molecular weight of HDPE decreases with the increase of ultrasonic intensity and increases and trends forward that of undegraded HDPE with the increase of distance from ultrasonic probe tip, indicating that attenuation of ultrasonic intensity in HDPE melt is very quick. Ultrasonic degradation kinetics of HDPE melt obeys the equation: Mt=M(infinity) + Ae(-kt). The theoretic calculation by this equation accords well with the experimental results. The plausible ultrasonic degradation mechanism of polymer melt based on molecular relaxation was also proposed in this paper.

Journal Article↗
PubMed1999

Ultrasonic determination of chicken composition.

An ultrasonic technique has been developed for measuring the composition of chicken meat. The relationship between the composition and ultrasonic velocity of chicken meat was determined using chicken analogues of different composition, prepared from dried chicken powder, corn oil, and distilled water. The ultrasonic velocity of chicken analogues was measured at temperatures from 5 to 35 degrees C using an ultrasonic spectrometer. The ultrasonic velocity increased with solids-nonfat (SNF) content at all temperatures but had a more complex dependence on fat content. Around 15 degrees C the ultrasonic velocity was independent of fat content; however, at lower temperatures it increased with fat content, and at higher temperatures it decreased. Semiempirical equations were developed to describe the relationship between ultrasonic velocity and chicken composition. To determine the usefulness of these equations, the ultrasonic velocities of various chicken meats were measured. The compositions of the chicken meats predicted on the basis of ultrasonic measurements were in good agreement with those determined by using standard methods (r(2) > 0. 97). The ultrasonic technique could also be used to measure the solid fat content of chicken fat. This study shows that ultrasonic velocity measurements can be used to characterize chicken composition. This method has great potential for application in the food industry because it is simple, fast, nondestructive, and reliable.

Animals↗
PubMed2005

Effects of ultrasonic intensity and reactor scale on kinetics of enzymatic saccharification of various waste papers in continuously irradiated stirred tanks.

Based on the enzymatic saccharification of the various pulps in the previous 0.8 l ultrasonic stirred tank reactor, the ultrasound-enhanced saccharification of waste papers such as newspaper, carton paper, office paper etc. was carried out in the same reactor as well as larger scale stirred tank reactors of size 3.2 and 6.4 l. The saccharification of each waste paper was less enhanced in the larger reactor at a given ultrasonic intensity. This could be attributed to the decrease in the ultrasonic intensity per reaction volume, i.e., the specific ultrasonic intensity. Most waste papers were more efficiently hydrolyzed with increasing specific ultrasonic intensities, although newspaper was less efficiently done for a too high specific intensity. Such an adverse effect might be due to the fact that some impurities in the newspaper such as lignin were activated by an intensive ultrasonic irradiation to form a rigid and closed network, which inhibited the access and adsorption of cellulase on to the substrate surface. The previous kinetic model was found to be applicable to analyze and simulate the saccharification of each waste paper in the different ultrasonic reactors. The ultimate conversion of a substrate based on the total sugar concentration estimated for an infinite reaction time could be correlated as a function of the ratio of initial substrate to enzyme concentrations at a fixed specific ultrasonic intensity. Either the apparent rate constant or the ultimate conversion increased and tended to approach a constant with an increase in the specific ultrasonic intensity except for the case of newspaper, while neither the apparent Michaelis constant, product inhibition constant nor glucose formation equilibrium constant was influenced by the specific ultrasonic intensity.

Avidin↗
PubMed1998

Heat generation during ultrasonic instrumentation of dentin as affected by different irrigation methods.

Heat is produced by magnetostrictive ultrasonic scalers which may cause injury to pulpal and periodontal tissues. Water coolant flows around the instrument stack and is directed at the instrument tip to reduce the generation of heat. Sound surgical practice requires the use of a sterile coolant for ultrasonic scaling during surgery. Intermittent bulb irrigation is one way to deliver sterile coolant when using ultrasonic scalers not equipped with a dedicated sterile water reservoir. The purpose of this study was to compare the temperature rise in dentin during ultrasonic scaling using either ultrasonic handpiece irrigation or intermittent bulb irrigation. Twenty dentin/cementum root slabs were prepared for each thickness of 0.5, 1.5, and 2.5 mm. A 3.0 mm x 1.5 mm field was outlined on each slab to indicate the area of intended instrumentation. Each slab was mounted such that a thermocouple placed in contact with dentin opposite the area of instrumentation was shielded from irrigation. Twenty samples of each thickness were ultrasonically scaled during which dentin temperature was recorded every 5 seconds over a 30-second period. All 60 slabs were first treated with dental unit ultrasonic handpiece water irrigation, followed by no irrigation, and finally by bulb irrigation with sterile saline. Repeated measures analysis of variance indicated that there were differences among the three treatment groups for temperature change over the course of the study (P < 0.001). Dentin temperature increased with both decreasing slab thickness and with increasing duration of instrumentation. However, only scaling without irrigation produced a rise in dentin temperature from baseline to a level reported as deleterious to pulpal and periodontal tissues. Bulb syringe irrigation delivered as a continuous drip and ultrasonic unit water spray minimized heat generation to physiologically tolerable levels. Intermittent bulb irrigation appears to be a satisfactory alternative to use of ultrasonic scaler water spray for cooling during ultrasonic scaling at surgery.

Analysis of Variance↗
PubMed2001

Effectiveness of the ultrasonic coagulating shears, LigaSure vessel sealer, and surgical clip application in biliary surgery: a comparative analysis.

Advancements in laparoscopic surgery are often dictated by the limitations of technical instrumentation. Energy sources other than electrosurgery have become popular with the promise of quick and effective vascular control. With their success surgeons have begun using these on structures other than blood vessels with little or no data establishing their efficacy or safety. This study evaluates alternative energy sources in sealing ductal structures for possible use in liver or gallbladder surgery. After elective cholecystectomy cystic ducts (n = 45) were resealed ex vivo with surgical clips (n = 14), ultrasonic coagulating shears (n = 16), or electrothermal bipolar vessel sealer (n = 15), and bursting pressures were measured. Nineteen additional human cystic ducts were randomized to seal by ultrasonic coagulating shears (n = 9) or electrothermal bipolar vessel sealer (n = 10) and fixed in 10 per cent buffered formalin for histologic evaluation of thermal spread (mm). After this nine adult pigs were randomized to laparoscopic ligation and transection of the common bile duct using surgical clips (n = 3), ultrasonic coagulating shears (n = 3), or electrothermal bipolar vessel sealer (n = 3). The animals underwent necropsy for assessment of seal integrity on the sixth postoperative day. In the ex vivo study the mean cystic duct bursting pressure was 621 mm Hg with surgical clips and 482 mm Hg with the electrothermal bipolar vessel sealer (P = 0.39). The mean cystic duct bursting pressure after ultrasonic coagulating shears was 278 mm Hg, which was statistically less than surgical clips (P = 0.007) and electrothermal bipolar vessel sealer (P = 0.02). The mean thermal spread was 3.5 mm for ultrasonic coagulating shears and 13.4 mm for electrothermal bipolar vessel sealer (P = 0.0002). All animals undergoing ligation and transection of the common bile duct with ultrasonic coagulating shears and electrothermal bipolar vessel sealer developed bile peritonitis by postoperative day 6 as a result of seal leak. All animals undergoing surgical clip ligation and transection of the common bile duct maintained seal integrity. The mean common bile duct pressure above the surgical clip was 12 mm Hg (range 10-14). In conclusion the acute ex vivo study demonstrated a significant difference in the cystic duct bursting pressure between surgical clips and ultrasonic coagulating shears and between electrothermal bipolar vessel sealer and ultrasonic coagulating shears. The ultrasonic coagulating shears and electrothermal bipolar vessel sealer failed to maintain seal integrity in the in vivo animal study. Given the failure of the ultrasonic coagulating shears and electrothermal bipolar vessel sealer in the animal model these energy sources should not be used for transection of the cystic duct or major hepatic ducts during hepatobiliary surgery.

Animals↗
PubMed2004

[Organic pollutants biodegradation in micro-polluted water enhanced by ultrasonic].

The effect of ultrasonic on the biotreatment of micro-polluted source water in a membrane bioreactor was studied through contrast experiments between the membrane bioreactor with and without ultrasonic. The results showed that ultrasonic at proper intensity could improve biological activity, increase organic load of the bioreactor, and enhance the removal of organic matters. The study of TTC-DHA of the bacteria and apparent molecular size distribution (AMSD) of organic compounds in the influent and effluent in the contrast experiments further proved that ultrasonic enhanced the bioactivity of the membrane bioreactor. The experiments with ultrasonic at different powers showed that ultrasonic at 10 W enhanced bioactivity most effectively. The effect of ultrasonic changed with running time. It was found that ultrasonic effect could be maintained for 24 hours, so the interval of ultrasonic treatment could be set at 24 hours. The mechanism of biological activity enhancement by ultrasonic was also investigated.

Biodegradation, Environmental↗
PubMed1998

Validating of a transoesophageal ultrasonic-Doppler-probe to the detection of air in the venous blood.

OBJECTIVES: The aim of this study was to compare the sensitivity of a newly applied transoesophageal ultrasonic Doppler sensor for detection of air with the traditional precordial ultrasonic Doppler sensor in clinical use. METHODS: We studied 16 patients undergoing neurosurgical procedures in a sitting position. Two ultrasonic Doppler devices were compared as to their ability to detect venous air embolisms (VAE): transoesophageal (ODM II, co. Abbott) versus a precordial ultrasonic Doppler sensor (Parks Medical Electronics Inc.). After establishing general anaesthesia and endotracheal intubation, we applied an ultrasonic Doppler sensor to the right sternal border of the patient's chest and inserted an ultrasonic Doppler probe into the oesophagus. With the patient in the sitting position, microparticularly d-galactose was injected to verify the efficacy of both ultrasonic Doppler devices. RESULTS: Using ODM II by positioning the probe toward the azygos vein, a dosage of 1 ml microparticularly d-galactose was detected in every patient. When adjusting the ODM II-probe on the right myocardial wall or using the precordial ultrasonic Doppler sensor, the administration of microparticularly d-galactose was detected by the devices in only 11 patients. CONCLUSIONS: This study demonstrates that a transoesophageal ultrasonic Doppler sensor (ODM II) is more efficient than the precordial ultrasonic Doppler sensor for monitoring patients who are at risk of VAE by sonification of the azygos vein.

Air↗
PubMed2006

Physics and mechanism of ultrasonic impact.

More and more experts and researchers in industry express their interest in the application of deformation effects of various peening techniques on the metal surface. This is primarily due to a relatively simple directional change in condition at the surface and in sub-surface layers of the material as a result of plastic deformation due to impulses of force caused, among other things, by converting ultrasonic oscillations of various impacting elements (indenters) at the treated surface. These effects are of a stochastic nature and their duration (or the time of impact) is generally measured in units of microseconds. To obtain relatively uniform coverage, an operator may use several treatment passes. However, a stochastic nature of single impacts makes it difficult to obtain a uniform distribution of deformations and hence surface characteristics as specified, in particular, by the engineering standards. We have developed the methods and means of implementing the ultrasonic impact and controlling its parameters. A fundamental distinction of the ultrasonic impact is that its duration is measured in the range from hundreds of microseconds to units of milliseconds, while the parameters responsible for the effects upon the surface may be adjusted according to the task. It is important to note that in the frequency range of processing ultrasound of up to 80 kHz this feature of the ultrasonic impact allows utilizing the plastic deformation region as a matched membrane to transmit ultrasonic oscillations and excite ultrasonic stress waves in the material being treated. These phenomena, in turn, initiate highly effective relaxation processes, plastic deformation and, as a result thereof, effects upon the structure and properties of the material, which are adequate to the task. This paper describes the theory and the results of the experimental investigations into the physics of the ultrasonic impact. Also, the mechanism of the ultrasonic impact implementation based on high-power ultrasonic transducers is addressed. The paper is aimed at engineers and researchers in the area of industrial application of high-power ultrasonics.

Journal Article↗
PubMed1998

A comparison of clinical and ultrasonic estimation of fetal weight.

OBJECTIVE: To compare the accuracy of routine ultrasonic and clinical birth weight estimation. METHODS: The study sample included 1717 women with singleton pregnancies, admitted in early labor with an ultrasonic estimated fetal weight (EFW) performed during the preceding week. Clinical EFW was obtained before rupture of the membranes by the attending senior resident, who was unaware of the ultrasonic EFW. Accuracy was determined by the percentage error, the absolute percentage error, and the proportion of estimates within 10% of the actual birth weight (birth weight +/- 10%). Statistical analysis was done by the paired t test, the comparison of correlated variances, the Wilcoxon sign test, and the chi2 test. Actual birth weight in the study sample averaged 3334+/-607 g (+/- standard deviation, [SD]) and ranged between 690 and 5320 g. RESULTS: The means of all error terms of the clinical EFW were significantly smaller than those of the ultrasonic EFW. However, the rates of estimates within 10% of birth weight were not significantly different (72 and 69%, respectively). In birth weights less than 2500 g, both methods overestimated the birth weight, but the mean errors of the ultrasonic EFW were significantly smaller than those of the clinical EFW. The ultrasonic EFW had significantly higher rates of birth weight +/- 10% than the clinical EFW (63 compared to 49%, respectively). In the 2500-4000 g birth weight, only the clinical EFW had no systematic error, whereas the ultrasonic EFW underestimated the birth weight. The mean errors of the clinical EFW were significantly smaller and the rate of birth weight +/- 10% significantly higher than those of the ultrasonic EFW. In the birth weight greater than 4000 g, both methods underestimated the birth weight, and the mean errors and the rate of estimates within 10% of birth weight were similar for both methods. CONCLUSION: Clinical estimation of birth weight in early labor is as accurate as routine ultrasonic estimation obtained in the preceding week. In the lower range of birth weight (less than 2500 g), ultrasonic estimation is more accurate; in the 2500-4000 g range, clinical estimation is more accurate. In the higher range of birth weight (greater than 4000 g), both methods have similar accuracy.

Adult↗
PubMed2004

[Ultrasonic wave propagation characteristics of cancellous bone].

Ultrasonic measurements of bone status or bone mass density are generally performed using ultrasonic parameters consisting of the slope of frequency-dependent attenuation (or broadband ultrasound attenuation: BUA) and the speed of sound (SOS). Many results of in vitro laboratory measurements and in vivo clinical trials have shown the ultrasonic parameters, BUA and SOS correlate significantly with the bone mass density measured by X-ray method. However, there exists some problem inherent in the ultrasonic method on the reproducibility and the uncertainty of measured ultrasonic parameters. The ultrasonic properties of cancellous bone have been experimentally and theoretically studied by author's group to reveal problems inherent in the ultrasonic method. According to experimental and theoretical studies, two longitudinal waves, fast wave and slow wave are clearly observed. The propagation speed of the fast wave increases with the bone density and that of the slow wave decreases very slightly with the bone density. Whereas the attenuation constant of the fast wave is much higher than that of the slow wave and is almost independent of the bone density, but in contrast, the attenuation constant of the slow wave increases considerably with the bone density. Experimental results on transmitted ultrasonic wave through cancellous bone show that the amplitude of the slow wave decreases with the bone density and the amplitude of the fast wave, on the contrary, increases with the bone density. This dependence of the fast wave amplitude on the bone density can not be explained by the attenuation constant. The ultrasonic wave propagation path through cancellous bone is modelized to clarify the propagation phenomenon and to specify the causality between ultrasonic wave parameters and the bone density. The bone density is quantitatively formulated based on the modelization as a function of the amplitude and the propagation speed of the fast wave.

Bone Density↗
PubMed1996

Randomized comparison of ultrasonic aspiration versus conventional electrocautery for dissection of the human internal thoracic artery.

The most common technique currently employed to harvest the internal thoracic artery for coronary artery bypass grafting is conventional electrocautery. This study compared an alternative method, electrocautery with an ultrasonic aspirator, for harvesting the internal thoracic artery. Patients were randomly assigned to one of six experimental groups (conventional electrocautery, ultrasonic aspirator at settings of 60%, 80%, and 100% power output, and ultrasonic aspirator in 100% CAVI-Pulse modes 1 and 3). Ring segments of internal thoracic artery were studied in an organ bath. Contraction responses were elicited with 123 mmol/L potassium physiologic salt solution, KPSS, KPSS solution containing noradrenaline, and a cumulative noradrenaline dose-contraction curve. Relaxation studies were performed with the vasodilators acetylcholine, bradykinin, and sodium nitroprusside. Forty percent of the electrocauterized vessels were traumatized or damaged and failed to respond to contractile stimuli, whereas only 10% of the vessels in ultrasonic aspirator groups 60%, 80%, and 100% failed to respond. All vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 1 responded, whereas 20% of the vessels in the group harvested by ultrasonic aspirator in 100% CAVI-Pulse mode 3 failed to respond. All settings of electrocautery with an ultrasonic aspirator produced a greater contractile response to KPSS and noradrenaline. Acetylcholine and sodium nitroprusside produced similar relaxations in all groups, but the bradykinin responses were significantly improved in all groups undergoing 100% electrocautery with an ultrasonic aspirator. These results suggest that 100% electrocautery with an ultrasonic aspirator, particularly in 100% CAVI-Pulse mode 1, resulted in less damage and trauma than conventional electrocautery during harvesting of the internal thoracic artery.

Adult↗
PubMed2002

Comparison of sonic and ultrasonic phacoemulsification using the Staar Sonic Wave system.

PURPOSE: To compare the performance of sonic phacoemulsification with that of ultrasonic phacoemulsification in regard to 1-day postoperative visual acuity, corneal edema, and procedure efficiency. SETTING: Oregon Eye Institute, Eugene, Oregon, USA. METHODS: This prospective nonrandomized study comprised 86 eyes with mild to moderate nuclear sclerotic cataract. Forty-three eyes had sonic and 43 ultrasonic phacoemulsification using the Staar Sonic Wave phacoemulsification system. The mean age was 76 years in the ultrasonic group and 71 years in the sonic group. The mean nuclear sclerosis was 2.0+ in the sonic group and 1.9+ in the ultrasonic group. Patient age, lens density, postoperative corneal edema, 1-day postoperative uncorrected visual acuity (UCVA), and the percentage of eyes with a visual acuity of 20/40 or better were determined. In addition, the mean ultrasonic and sonic times, mean percentage phaco power, and mean effective phaco time (EPT) were calculated in each group. RESULTS: Both groups had a 5% incidence of trace corneal edema. The mean UCVA was 20/41 in the ultrasonic group and 20/42 in the sonic group. Seventy-nine percent of eyes in the ultrasonic group and 74% in the sonic group had a UCVA of 20/40. The mean percentage phaco power was 7.2% and 7.6% in the ultrasonic group and sonic group, respectively. The mean EPT was low in both groups, 4.0 and 2.9 seconds, respectively. CONCLUSION: Sonic technology yielded outcomes similar to those of ultrasonic phacoemulsification with respect to postoperative visual acuity and corneal edema in patients with average density nuclear sclerotic cataract.

Corneal Edema↗
PubMed2001

A comparative in vitro study of a magnetostrictive and a piezoelectric ultrasonic scaling instrument.

BACKGROUND: The effects of magnetostrictive ultrasonic instruments and piezoelectric ultrasonic instruments on tooth surfaces seem to differ with regards to root debridement. AIM: The purpose of this study was to compare a magnetostrictive ultrasonic scaling instrument with a piezoelectric ultrasonic scaling instrument and a hand curette regarding time taken, calculus removal, tooth surface roughness (Ra), and SEM examination before and after instrumentation. METHODS: 30 extracted human teeth with subgingival calculus were assigned to one of three treatment groups (n=10). The working force was standardised for both ultrasonic instruments at 200 g and for the curette at 500 g. RESULTS: The results revealed that the time needed for instrumentation was 126.1+/-38.2 s for the curette, significantly more than for the piezoelectric ultrasonic instrument (74.1+/-27.6 s; p<0.05) and 104.9+/-25.4 s for the magnetostrictive ultrasonic instrument. Remaining calculus was similar for all three groups. The end Ra values were significantly worse for the piezoelectric instrument (2.02+/-0.41; p<0.05) compared to 1.42+/-0.48 for the curette and 1.36+/-0.41 for the magnetostrictive instrument. The SEM examination revealed the smoothest surfaces but, subjectively, the most tooth substance loss after the curette, followed by the magnetostrictive instrument, with the least substance loss, and then the piezoelectric instrument, with medium substance loss. CONCLUSION: The piezoelectric ultrasonic scaler was more efficient than the magnetostrictive ultrasonic scaler in removing calculus but left the instrumented tooth surface rougher.

Analysis of Variance↗
PubMed2004

Evaluation of ultrasonically placed MTA and fracture resistance with intracanal composite resin in a model of apexification.

The purpose of this study was to evaluate whether intracoronal delivery of an apical barrier of mineral trioxide aggregate (MTA) placed ultrasonically, non-ultrasonically, or ultrasonically with the addition of an intracanal composite resin provided a better seal against bacterial leakage. A second purpose was to determine whether intracanal composite resin or gutta-percha and sealer placed against an apical barrier of MTA provided greater resistance to root fracture. In a standardized in vitro open apex model, MTA was placed as an apical barrier at a thickness of 4 mm, with and without ultrasonic vibration. The barriers were challenged with bacteria exposure within a leakage model, and fracture resistance was assessed with increasing forces applied via an Instron machine. After 45 days, the addition of ultrasonics significantly improved the MTA seal, compared with the non-ultrasonics treatment (Kruskal Wallis nonparametric ANOVA with Dunn multiple comparison test p < 0.05). Bacterial leakage occurred in 6 (33%) of 18 in the non-ultrasonic MTA group, 2 (11%) of 18 in the ultrasonic MTA group, and 1 (6%) of 18 in the ultrasonic MTA-composite group. There were no significant differences at 90 days. A 4-mm thickness of MTA followed with an intracanal composite resin demonstrated a significantly greater resistance to root fracture than MTA followed with gutta-percha and sealer (one-way ANOVA with Newman-Keuls multiple comparison test, p < 0.01). The MTA-gutta-percha group was not significantly different than the MTA unrestored positive control.

Aluminum Compounds↗
PubMed2006

Comparison of ultrasonic cleaning schemes: a pilot study.

OBJECTIVE: Ultrasonic cleaning is an effective method for cleaning dental instruments prior to sterilisation. However, there are few studies that directly compare precleaning and ultrasonic cleaning solutions. This study evaluated the efficacy of different ultrasonic cleaning schemes. METHOD AND MATERIALS: Twenty representative dental instruments, five of which were soiled with a mixture of blood and hydroxyapatite, were used in a series of cleaning runs. Cleaning employed a presoaking agent, ultrasonic cleaning, or a combination of both. Two presoaking agents (Non-ionic Ultrasonic Cleaning Solution and ProEZ Foaming Enzymatic Spray) plus five ultrasonic cleaners (UltraDose, General Purpose Cleaner, Co-enzyme Concentrate, Enzol Enzymatic Detergent, and Non-ionic Ultrasonic Cleaning Solution) were compared, with tap water serving as a control. There were two cleaning times: seven and 15 minutes. After rinsing, the working ends of the instruments underwent scrubbing for 20 seconds using a dental polishing brush held in a haemostat. After scrubbing, the brush and instrument were placed in a tube containing sterile saline. Vortexing of the tube lasted 30 seconds. Testing for the post-cleaning presence of blood involved Hemastix dipsticks. These sticks measure minute amounts of blood in urine and can detect as few as 35 red blood cells per ml. Comparisons of colour change were made to a standard scale followed by assignment of numeric values. RESULTS: Tap water was the poorest cleaning solution, while UltraDose was the most effective. Blood removal improved when cleaning time was increased from seven to 15 minutes. The combined effect of a presoak immersion followed by ultrasonic cleaning was the most effective cleaning scheme overall. Cleaning by either ultrasound or presoaking only was less effective. Some instruments were more difficult to clean than others. CONCLUSION: Within the constraints of the small number of test runs performed, it was concluded that application of a presoak agent before ultrasonic cleaning produced the most effective instrument-cleaning regimen.

Blood↗
PubMed2005

Determination of the heat stability profiles of concentrated milk and milk ingredients using high resolution ultrasonic spectroscopy.

In the present work, we used high resolution ultrasonic spectroscopy for the analysis of heat coagulation process in milks. Two skim milks recombined from powder samples differing by their preheating treatments as well as dairy ingredients (phosphocasein, whey protein isolate, and a milk model) were monitored while submitted to a temperature of 120 degrees C. Three stages in the precoagulation and coagulation processes can be distinguished in the ultrasonic velocity and attenuation profiles. The first stage shows a very sharp decrease in ultrasonic velocity and increase in ultrasonic attenuation. This could be attributed to fast denaturation and aggregation of whey proteins and precipitation of calcium phosphate. In the second stage, small changes in ultrasonic velocity are observed, the rate of which depends on the nature and pH of the samples. In the third stage, a sharp decrease in ultrasonic velocity and attenuation is recorded for all samples, which corresponds to the coagulation and formation of the gel network. After coagulation, a very small change in ultrasonic velocity and attenuation was observed. From the ultrasonic measurements, we determined the heat stability vs. pH profiles of the different samples studied. The observed ultrasonic attenuation profiles were also interpreted in terms of changes in the size of casein micelles and coagulation processes.

Animals↗