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PubMed2002

Effects of occupational ultrasonic noise exposure on hearing of dental hygienists: a pilot study.

PURPOSE: The purpose of this case-control study was to determine whether long-term ultrasonic noise exposure via the dental office environment is related to dental hygienists' hearing status. METHODS: Registered dental hygienists (N = 698) who live in the Hampton Roads areas of Virginia were mailed a Dental Hygiene Work History Questionnaire to determine who would meet the inclusion criteria and would be willing to participate in the study. Consenting subjects were categorized into one of two groups, according to ultrasonic scaler usage rate, and matched on age. Persons with known hearing loss due to infection, disease, or congenital defect were excluded from the study. The final sample consisted of 20 dental hygienists with a high ultrasonic usage rate and a matched group of 20 dental hygienists who had a low ultrasonic usage rate. Once the groups were formed, a certified audiologist tested subjects' hearing in each ear via the pure-tone audiometer. Audiometric data were analyzed using the analysis of variance for repeated measures procedure to determine if degree of ultrasonic scaler noise exposure in the dental office environment was significantly related to hearing status in these dental hygienists. RESULTS: Results revealed that the right and left ears were not statistically different in the hearing threshold levels, regardless of group status. However, there was a significant difference in the high ultrasonic usage group and the low ultrasonic usage group at the 3000 Hz. No differences were found at the frequencies of 500, 1000, 2000, 4000, 6000, and 8000 Hz. CONCLUSIONS: Based on these outcomes, the ultrasonic scaler is not considered to have a negative effect on the hearing of dental hygienists at 500, 1000, 2000, 4000, 6000, and 8000 Hz, but may be related to hearing loss at 3000 Hz. Ultrasonic noise may in fact be affecting dental hygienists' hearing at 3000 Hz, but loss of hearing observed at the higher frequencies may be attributed to other unidentified factors present in both groups.

Adult↗
PubMed2006

[Study on the extraction of the active component in Atractylode macrocephala with ultrasonic wave technology optimized by the response surface method].

OBJECTIVE: To create Atractylode macrocephala inspissation decoction pieces. The effect of ultrasonic wave on extraction of the active components in A. macrocephala was studied in a water solution. METHOD: The factors including the ratio of material to liquid, ultrasonic power, ultrasonic time, soaking time, particle size etc, were studied. The best extraction method was found through the response surface method. RESULT: The best extraction method was found as follows: the granularity of material 0.1 mm, the repetition times of ultrasonic process 3 times, the soaking time before the ultrasonic process 30 min, the ratio of liquid to material 10:1, the soaking time after the ultrasonic process 2.6 h, the time of the ultrasonic wave 15.5 min, the power of the ultrasonic wave 531 W, the rate of reservation of active components 88.5%, the rate of inspissation 1.6. CONCLUSION: The ultrasonic wave can used in the extraction of the active components in A. macrocephala and a model equation that can be used to predict the experiment was get through the response surface method.

Atractylodes↗
PubMed1989

[Mechanical characteristics of ultrasonic device for root canal treatment].

Recently, many studies have demonstrated the superiority of the ultrasonic devices in endodontic treatment, while other reports did not recognize the advantage of the ultrasonic instrumentation over hand instrumentation. This disagreement in opinion might be due to the fact that the mechanical characteristics of ultrasonic devices have not been clarified. Therefore, some factors which might contribute to the mechanical characteristics of ultrasonic device for root canal treatment were examined. These factors were: (a) applied force on file; (b) angle of connector; (c) position of substrate material being cut; (d) filing speed; and (e) resonance of file. These factors were examined by measuring the cutting depth on acrylic wafer using the cutting efficiency testing apparatus. This apparatus with a push-pull stroke approximately 4 mm in length, was propelled the root canal instruments in linear motion. The filing speed was adjusted to 100 strokes per minute. The results were as follows: 1. The greater load was given to the file, the higher was the cutting ability of ultrasonic device. But cutting efficiency of #15, #25 and #35 files were inhibited over the load of 50, 60 and 70g each. It was considered that the adequate load for filing utilized ultrasonic device was #15:50g, #25:60g and #35:70g. 2. The file attached to the angled connector had a cantilevered vibration. And the cutting ability was effected by connector angle. The 120 degree-type connector was more effective than straight type (180 degree-type connector). 3. Substrate materials were made deeper cut when it was applied against the vibrating direction of the file than were applied at right angle to vibrating direction of the file. 4. Cutting efficacy of ultrasonic device was evaluated under the conditions as filing speed of 25, 50 and 100 strokes/min by comparing each ratio of cutting depth per total number of filing strokes after 20 minutes. The ultrasonic vibration showed tighter cutting ability when this ultrasonic device was operated 25 strokes/min. 5. Cutting efficiency of two methods was examined under the same amplitude. One was to set up the file length slightly shifted from the resonance point and to give the amplitude to file using resonance phenomenon. The other was to set up the file length of nonresonance condition and to give the amplitude by power supplying from the device. The latter showed higher cutting ability without the risk of the file fracture.(ABSTRACT TRUNCATED AT 400 WORDS)

Equipment Design↗
PubMed2006

Estimation of clamping force in high-tension bolts through ultrasonic velocity measurement.

The estimation of clamping force has been regarded as the main issue in the maintenance of high-tension bolts. This paper proposes a method which uses the dependency of ultrasonic velocity on stress based on the nonlinear elastic effect. The variation of ultrasonic velocity in the range of actual stress acting in the bolt is very small so that the precise measurement of ultrasonic velocity is needed. In this paper, we adopt a method to measure ultrasonic velocity, where the TOF (time of flight) of a tone-burst ultrasonic wave is precisely measured by using the phase detection technique. In order to verify the usefulness of the proposed method, two kinds of experiments are carried out. The first one measures ultrasonic velocity when the bolt is stressed by the tension tester, and from this, the exact axial force acting in the bolt can be determined. The results show good agreement with the expected linear relationship between ultrasonic velocity and axial stress. The second experiment measures ultrasonic velocity when the bolt is stressed by the torque wrench. The results show that ultrasonic velocity decreased as the torque increased, which is identical to the theoretically expected tendency. From these results, it can be said that the proposed method is adequate in evaluating clamping force in high-tension bolts.

Journal Article↗
PubMed1999

Measurement of obstetric conjugate by ultrasonic tomography and its significance.

OBJECTIVE: The purpose of this study was to investigate the clinical usefulness of the measurement of ultrasonic obstetric conjugate. STUDY DESIGN: In 209 pregnant women, ultrasonic obstetric conjugate was measured twice at 28 and 36 weeks of pregnancy. In 26 of these patients the measurement of obstetric conjugate by x-ray pelvimetry was also performed at 36 weeks of pregnancy because of medical indications. Obstetric outcome was investigated in association with ultrasonic obstetric conjugate. The relationship between ultrasonic obstetric conjugate and x-ray pelvimetry was investigated. RESULTS: Ultrasonic obstetric conjugate ranged from 10.7 to 15.1 cm. In 12 patients (5.7%) ultrasonic obstetric conjugate was less than 12 cm. Six of them (50.0%) underwent cesarean section because of dystocia. This percentage was significantly higher than 7.1% of the cesarean section rate (14 of 197) in patients with ultrasonic obstetric conjugate more than 12 cm (P <.001). A close positive correlation was observed between ultrasonic obstetric conjugate and x-ray pelvimetry (r = 0.91; P <.0001). CONCLUSIONS: We conclude that ultrasonic obstetric conjugate measurement is a safe and useful procedure in the prediction of dystocia.

Adult↗
PubMed2002

Investigation of ultrasonic properties of PAG and MAGIC polymer gel dosimeters.

Ultrasonic speed of propagation and attenuation were investigated as a function of absorbed radiation dose in PAG and MAGIC polymer gel dosimeters. Both PAG and MAGIC gel dosimeters displayed a dependence of ultrasonic parameters on absorbed dose with attenuation displaying significant changes in the dose range investigated. The ultrasonic attenuation dose sensitivity at 4 MHz in MAGIC gels was determined to be 4.7 +/- 0.3 dB m(-1) Gy(-1) and for PAG 3.9 +/- 0.3 dB m(-1) Gy(-1). Ultrasonic speed dose sensitivities were 0.178 +/- 0.006 m s(-1) Gy(-1) for MAGIC gel and -0.44 +/- 0.02 m s(-1) Gy(-1) for PAG. Density and compressional elastic modulus were investigated to explain the different sensitivities of ultrasonic speed to radiation for PAG and MAGIC gels. The different sensitivities were found to be due to differences in the compressional elastic modulus as a function of dose for the two formulations. To understand the physical phenomena underlying the increase in ultrasonic attenuation with dose, the viscoelastic properties of the gels were studied. Results suggest that at ultrasonic frequencies, attenuation in polymer gel dosimeters is primarily due to volume viscosity. It is concluded that ultrasonic attenuation significantly increases with absorbed dose. Also, the ultrasonic speed in polymer gel dosimeters is affected by changes in dosimeter elastic modulus that are likely to be a result of polymerization. It is suggested that ultrasound is a sufficiently sensitive technique for polymer gel dosimetry.

Acrylic Resins↗
PubMed2003

Ultrasonic techniques for imaging and measurements in molten aluminum.

In order to achieve net shape forming, processing of aluminum (Al) in the molten state is often necessary. However, few sensors and techniques have been reported in the literature due to difficulties associated with molten Al, such as high temperature, corrosiveness, and opaqueness. In this paper, development of ultrasonic techniques for imaging and measurements in molten Al using buffer rods operated at 10 MHz is presented. The probing end of the buffer rod, having a flat surface or an ultrasonic lens, was immersed into molten Al while the other end with an ultrasonic transducer was air-cooled to room temperature. An ultrasonic image of a character "N", engraved on a stainless steel plate immersed in molten Al, and its corrosion have been observed at 780 degrees C using the focused probe in ultrasonic pulse-echo mode. Because cleanliness of molten Al is crucial for part manufacturing and recycling in Al processing, inclusion detection experiments also were carried out using the nonfocused probe in pitch-catch and pulse-echo modes. Backscattered ultrasonic signals from manually added silicon carbide particles, with an average diameter of 50 microm, in molten Al have been successfully observed at 780 degrees C. For optimal image quality, the spatial resolution of the focused probe was crucial, and the high signal-to-noise ratio of the nonfocused probe was the prime factor responsible for the inclusion detection sensitivity using backscattered ultrasonic signals. In addition, it was found that ultrasound could provide an alternative method for evaluating the degree of wetting between a solid material and a molten metal. Our experimental results showed that there was no ultrasonic coupling at the interface between an alumina rod and molten Al up to 1000 degrees C; therefore, no wetting existed at this interface. Also because ultrasonic velocity in alumina is temperature dependent, this rod proved to be able to be used as an in-line temperature monitoring sensor under 1000 degrees C in molten Al.

Journal Article↗
PubMed1994

Ultrasonic endarterectomy: experimental and initial clinical results in carotid stenosis.

PURPOSE: The effects of ultrasonic endarterectomy, evaluated experimentally and clinically, were compared with the results obtained with controversial endarterectomy. METHODS EXPERIMENTAL: An ultrasonic vascular dissector with a frequency of 29 kHz was used for ultrasonic endarterectomy. Gross and histologic observation was made on 22 fresh human cadaver atherosclerotic vessels, of which 16 were treated with ultrasound endarterectomy and 6 conventionally. Clinical: Twenty-eight patients requiring carotid endarterectomy were chosen at random. Seven patients underwent ultrasonic endarterectomy after traditional access surgery, while 21 patients were treated with conventional endarterectomy. In the clinical study, an intraoperative gross observation of the endarterectomized surfaces was made, followed by duplex scanning after 18 and 24 months. RESULTS: Histologic observation of the cadaveric revealed particularly smooth surfaces in 87.5%; there was no debris, flaps, or vessel damage in any of the ultrasonically treated samples. In contrast, the traditional technique produced regular surfaces without residual debris in only 50% of the experimental cases. Favorable results were also seen in the clinical carotid experience, in which there was no need to surgically correct the ultrasonically endarterectomized surface in any case. In fact, achieving a satisfactory outcome was greatly facilitated by the use of ultrasound. In the conventionally treated patients, however, only 19% (4) demonstrated a smooth luminal surface on gross observation even after surgical correction. No postoperative complications were encountered in either group, and no restenosis has occurred in ultrasonic endarterectomy-treated patients after 2 years. CONCLUSIONS: Favorable experimental results using ultrasonic endarterectomy prompted the successful clinical application of this new technique in carotid stenosis treatment. Whether or not ultrasonic endarterectomy can reduce postoperative morbidity and restenosis is still under study.

Aged↗
PubMed1987

Economic evaluation of extracorporeal shock wave lithotripsy, percutaneous ultrasonic lithotripsy, and standard surgical treatment of urolithiasis--a Canadian perspective.

In order to provide information for decision making regarding urolithiasis treatment programs for the population of the Central West Region (population 1.8 million) of Ontario, we conducted an incremental cost-effectiveness analysis of standard surgery, percutaneous ultrasonic lithotripsy, and extracorporeal shock wave lithotripsy for the removal of renal and ureteric stones. Estimates of costs and effects were calculated for a 5-year period, beginning in 1985. Direct medical costs estimated were fees, both professional and technical, operating costs, and hospitalization costs for standard surgery, percutaneous ultrasonic lithotripsy, and extracorporeal shock wave lithotripsy. Capital costs, opportunity costs, and depreciation were included for extracorporeal shock wave lithotripsy, but not for standard surgery or percutaneous ultrasonic lithotripsy, thus creating a bias against extracorporeal shock wave lithotripsy. All costs were expressed in 1985 Canadian dollars; both costs and effects from years 2-5 were discounted using a rate of 5%. The effects estimated were disability days. Failure rates, complication rates, length of hospital stay, and disability days were median values reported in the medical literature. Assuming 400 procedures per year (based on previous experience in the Central West Region), the total 5-year costs in millions of dollars, were 8.86 for standard surgery, 7.84 for extracorporeal shock wave lithotripsy, and 7.51 for percutaneous ultrasonic lithotripsy. Costs per procedure were 4,429 for standard surgery, 3,918 for extracorporeal shock wave lithotripsy, and 3,756 for percutaneous ultrasonic lithotripsy. The total disability days generated were 69,098 for standard surgery, 18,184 for percutaneous ultrasonic lithotripsy, and 9,092 for extracorporeal shock wave lithotripsy. Because standard surgery costs more and generates more disability days than either percutaneous ultrasonic lithotripsy or extracorporeal shock wave lithotripsy, it is clearly the least desirable alternative. At 400 procedures per year, the cost of each disability day averted by extracorporeal shock wave lithotripsy, compared to percutaneous ultrasonic lithotripsy, is $35.60. At 500 procedures per year, extracorporeal shock wave lithotripsy costs less and generates fewer disability days than percutaneous ultrasonic lithotripsy and is therefore the desired alternative. Sensitivity analyses demonstrate that cost effectiveness results are most affected by the number of procedures performed, the length of stay, and the number of disability days generated.

Cost-Benefit Analysis↗
PubMed2003

Randomized clinical trial of ultrasonic versus electrocautery dissection of the gallbladder in laparoscopic cholecystectomy.

BACKGROUND: Laparoscopic cholecystectomy is frequently complicated by gallbladder perforation and loss of bile or stones into the peritoneal cavity. The aim of this study was to compare the use of ultrasonic dissection and electrocautery with respect to the incidence of gallbladder perforation and intraoperative consequences. METHODS: Between January 1998 and January 2000, 200 patients undergoing elective laparoscopic cholecystectomy were randomized to electrocautery or ultrasonic dissection of the gallbladder. The main outcome measures were gallbladder perforation, operating time and the number of times the lens was cleaned. Univariate and multivariate analyses were performed. RESULTS: The perforation rate differed significantly: 16 per cent for ultrasonic dissection (n = 96) and 50 per cent for electrocautery (n = 103) (P < 0.001). The operating time of the least experienced surgeons, who had performed fewer than ten laparoscopic cholecystectomies, was significantly shorter when ultrasonic dissection was used, compared with electrocautery. The number of times the lens needed to be cleaned was significantly lower when ultrasonic dissection was used in complicated gallbladders (P < 0.035). At logistic regression analysis, the risk of perforation in the electrocautery group was about four times higher (odds ratio 0.26, P < 0.001) than that in the ultrasonic group. When the groups were matched for prognostic factors, including body mass index and surgical experience, the results were similar to those obtained with univariate and multivariate analysis. CONCLUSION: The use of ultrasonic dissection in laparoscopic cholecystectomy reduces the incidence of gallbladder perforation and helps the operation to progress. Less experienced surgeons benefit most from ultrasonic dissection, particularly in complicated intraoperative circumstances.

Adolescent↗
PubMed1992

The cavitational ultrasonic surgical aspirator for cytoreduction in advanced ovarian cancer.

OBJECTIVE: The cavitational ultrasonic surgical aspirator is a newer surgical instrument that has been shown to be effective in tumor resection. The purpose of this study was to evaluate its usefulness for cytoreduction of advanced ovarian cancer. STUDY DESIGN: Over a 24-month period patients with advanced ovarian cancer (stage IIIC and IV or bulky recurrent disease) were studied to determine the frequency of use of the cavitational ultrasonic surgical aspirator and the sites of tumor resection. The blood loss and operative time for patients who underwent surgery with the cavitational ultrasonic surgical aspirator were compared by Student t test with those of patients who did not undergo surgery with the cavitational ultrasonic surgical aspirator. RESULTS: The cavitational ultrasonic surgical aspirator was utilized to effect optimal cytoreduction in 22 of 45 patients (48%). Of 52 sites of disease resected, 23 (44%) involved sites difficult to resect with standard operative techniques. These sites included the diaphragm, liver, spleen, and fixed retroperitoneal adenopathy. The cavitational ultrasonic surgical aspirator allowed resection from other sites, precluding procedures with potentially more morbidity. Of all 45 patients, 86% had cytoreduction to less than 2 cm and 44% to less than 0.5 cm. The blood loss and operative time were not different between cases in which the cavitational ultrasonic surgical aspirator was used and those in which it was not used. CONCLUSION: The cavitational ultrasonic surgical aspirator appears to contribute to cytoreduction in patients with advanced ovarian cancer.

Diaphragm↗
PubMed1993

Shock-induced ultrasonic vocalization in young adult rats: a model for testing putative anti-anxiety drugs.

A putative animal model of anxiety based on shock-induced ultrasonic vocalization was pharmacologically validated in young adult rats. Suppression of shock-induced ultrasonic vocalization was obtained with diazepam, chlordiazepoxide, meprobamate and pentobarbital; the serotonin (5-HT)1A receptor agonists 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)tetralin], buspirone, ipsapirone, gepirone and tandospirone; the nonselective 5-HT receptor agonists TFMPP [1-(3-trifluoromethylphenyl)piperazin], mCPP [1-(3-chlorophenyl)piperazin] and DOI (1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane); the NMDA antagonists PCP (phencyclidine) and MK-801; the alpha 2-adrenoceptor antagonists idazoxane, yohimbine and 1-PP (1-pyrimidinylpiperazine); and the atypical neuroleptic clozapine. The alpha 2-adrenoceptor agonist clonidine, the 5-HT2/5-HT1C antagonist ritanserin, the 5-HT3 antagonists ondansetron and ICS-205,930, and the 5-HT reuptake inhibitor fluoxetine did not, or only partially, reduce ultrasonic vocalization. Tricyclic and tetracyclic, as well as some atypical antidepressants and a monoamineoxidase (MAO) inhibitor, showed no ultrasonic vocalization reducing effects, or reduced ultrasonic vocalization only at high doses. An opiate, an antimuscarinic, (pro)convulsants and typical neuroleptics did not reduce ultrasonic vocalization. The present findings suggest that the ultrasonic vocalization model specifically measures anxiolytic effects. Because ultrasonic vocalization responding develops within five days, remains stable for at least three months and gives highly reproducible results, the test appears suitable for rapid and repeated testing of new anxiolytics in the same animals.

Adrenergic alpha-Agonists↗
PubMed2005

Ultrasonic vocalization production of preweanling rats: effects of central and peripheral administration of alpha2-adrenoceptor agonists.

Stimulation of alpha2-adrenoceptors increases the ultrasonic vocalization production of preweanling rats, however it is not known whether these critical alpha2-adrenoceptors are located peripherally or centrally. In a series of three experiments, ultrasonic vocalizations were measured after 11-day-old rats had been administered clonidine or 2-[2,6-diethylphenylamino]-2-imidazole (ST-91) either systemically (i.p.) or into the third ventricle (i.c.v.). These particular alpha2-adrenoceptor agonists were chosen because clonidine is lipophilic and enters the central nervous system, while ST-91 is hydrophilic and does not readily cross the blood-brain barrier. In the third experiment, clonidine- (1 microg, i.c.v.) and ST-91-induced (15 microg, i.c.v.) ultrasonic vocalizations were measured after systemic injection of the alpha2-adrenoceptor antagonist yohimbine (0.5 or 1 mg/kg, i.p.). Results showed that central administration of both clonidine and ST-91 increased the ultrasonic vocalization production of 11-day-old rats, whereas peripheral administration of only clonidine, and not ST-91, increased ultrasonic vocalizations. These results indicate that the alpha2-adrenoceptors mediating ultrasonic vocalization production are located in the central nervous system. Yohimbine fully attenuated clonidine-induced ultrasonic vocalizations but only partially attenuated ST-91-induced vocalizations. This pattern of results may have been due to the differential selectivity of clonidine and ST-91 for alpha2-adrenoceptor subtypes (alpha2A, alpha2B, and alpha2C) or imidazoline receptors. When combined with past research, the present results are consistent with the hypothesis that centrally located alpha2-adrenoceptors are a component of a neural system that mediates ultrasonic vocalization production.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1997

Comparison of ultrasonic and high-speed-bur root-end preparations using bilaterally matched teeth.

The purpose of this study was to compare ultrasonic and high-speed-bur root-end preparations. Seventy-six roots from 29 bilaterally matched pairs of human teeth in cadavers were used in this study. In group 1 ultrasonic preparations were made in 38 roots and filled with amalgam. In group 2 high-speed bur preparations were made in 38 roots and filled with amalgam. The size of the bony crypt was measured and the teeth were extracted and radiographed mesial-distally and buccal-lingually. None of the root-end preparations resulted in root perforation. The mean mesial-distal minimum depth of ultrasonic and high-speed bur preparations were 2.11 mm and 1.39 mm, respectively. The mean buccal-lingual minimum depth of preparation was 2.51 mm for the ultrasonic and 2.05 mm for the high-speed bur preparations. The depth of the ultrasonic preparations was significantly greater for both measurements. A significantly greater bevel angle was associated with the bur preparations, 35.1 degrees versus 16.0 degrees for the ultrasonic preparations. The incidence of ultrasonic root-end preparations deviating from the uninstrumented canal spaces was found to be 2.6%. All bur root-end preparations were at an acute angle to the long axis of the root. The bony crypt size for bur preparations was significantly greater than that for ultrasonic preparations.

Cadaver↗
PubMed2003

How safe is high-power ultrasonic dissection?

OBJECTIVE: To evaluate the safety of ultrasonic dissection. SUMMARY BACKGROUND DATA: High-power ultrasonic dissection is in widespread use for both open and laparoscopic operations and is generally perceived to carry a low risk of collateral damage, but there is no published evidence for this. METHODS: Under controlled experimental conditions, ultrasonic dissections were performed in pigs using Ultracision (Ethicon) or Autosonix (Tyco/USSC) at the three power settings (3, 4, and 5) in random fashion to mobilize the cardia and fundus, bile duct, hepatic artery, portal vein, aorta from the inferior vena cava, renal vessels, colon, and ureters. The dissections (open and laparoscopic) were carried out on pigs at each power setting with each device. Thermal mapping of the tissues during dissection was performed with an infrared thermal camera and associated software. The animals were killed at the end of each experiment and specimens were harvested for quantitative histology. RESULTS: Extreme and equivalent temperature gradients were generated by ultrasonic dissection with both systems. Heat production was directly proportional to the power setting and the activation time. The core body temperature of the animals after completion of the laparoscopic dissections rose by an average of 2.3 degrees C. The zone around the jaws that exceeded 60 degrees C with continuous ultrasonic dissection for 10 to 15 seconds at level 5 measured 25.3 and 25.7 mm for Ultracision and Autosonix, respectively. At this power setting and an activation time of 15 seconds, the temperature 1.0 cm away from the tips of the instrument exceeded 140 degrees C. Although there was no discernible macroscopic damage, these thermal changes were accompanied by significant histologic injury that extended to the media of large vessels and caused partial- to full-thickness mural damage of the cardia, ureter, and bile duct. Collateral damage was absent or insignificant after dissections at power level 3 with both systems and an activation time not exceeding 5 seconds. CONCLUSIONS: High-power ultrasonic dissections at level 5 and to a lesser extent level 4 result in considerable heat production that causes proximity collateral damage to adjacent tissues when the continuous activation time exceeds 10 seconds. Ultrasonic dissections near important structures should be conducted at level 3. At power levels of 4 and 5, the ultrasonic energy bursts to the tissue should not exceed 5 seconds at any one time.

Animals↗
PubMed2006

A laboratory study to determine the effects of universal and rotating ultrasonic inserts on wrist movement and scaling time efficiency of dental hygienists.

PURPOSE: The purpose of this study was to determine if differences existed in range of wrist movements and scaling time efficiency of dental hygienists using a rotating ultrasonic insert when compared with a standard universal insert. METHODS: A convenience sample of 32 consenting experienced dental hygienists who met inclusion criteria was invited to participate. Using a cross-over research design, the 32 participants were randomly assigned to one of the two subgroups. Subgroup A (n = 16) used the rotating universal ultrasonic insert on a typodont, rested for 15 min and the standard universal insert on a different typodont. Subgroup B (n = 16) used the standard universal ultrasonic insert on a typodont, rested for 15 min and the rotating universal ultrasonic insert on a different typodont. Each participant used the rotating and standard universal ultrasonic scaling inserts to remove 2 cm3 artificial calculus from two different typodonts for up to 15 min per insert. Scaling time efficiency was determined using a Modified Volpe-Manhold Calculus Index, measuring the amount of artificial calculus remaining after ultrasonic scaling. While scaling, each participant wore the WristSensor goniometry gloves, which determined changes in wrist movements (flexion and extension and ulnar and radial deviations), measured as a deviation from the neutral position. RESULTS: A paired t-test (P = 0.05) using 30 subjects with useable data, revealed no statistically significant differences between the two different inserts in terms of wrist movements and scaling time efficiency. A multivariate analysis of variance revealed no statistically significant differences in the percentage of time dental hygienists were in high, medium or low-risk posture categories while using the rotating ultrasonic insert compared with the standard universal insert. Based on the results of this laboratory study, dental hygienists using a rotating ultrasonic insert appear to experience no ergonomic advantage in terms of wrist postures or timesavings over a standard insert.

Cross-Over Studies↗
PubMed1988

Ultrasonic plaque ablation. A new method for recanalization of partially or totally occluded arteries.

The potential application of ultrasonic energy for ablation of atherosclerotic plaques was studied in human atherosclerotic arteries with continuous and pulsed delivery of energy. With a prototype ultrasonic wire probe (n = 79 segments), there was gross reduction in vascular lesions as well as microscopic disruption of fibrous and calcified plaques. Normal portions of vessels appeared unaffected by the application of ultrasound. The prototype ultrasonic wire catheter ablated calcific deposits in less than 10 seconds. With this probe, all 26 complete atherosclerotic occlusions 0.5-5 cm in length were recanalized irrespective of the presence of calcium. Twenty-four of the segments were reopened in less than 20 seconds. By light microscopy, the site of plaque ablation was smooth, concave, and conformed to the shape of the probe tip. In 17 samples, there was evidence of thermal injury, and in six of the 79 samples studied with the prototype probe, there was vascular perforation. No vascular perforation occurred without thermal damage, when pulsed (rather than continuous) ultrasonic energy was used (n = 40) or when the duration of application was less than 30 seconds, with power output less than 25 W and with the probe oriented parallel to the wall (n = 26). Thus, by modifying the duration, mode, and magnitude of the ultrasonic power output, thermal injury and vascular perforation may be avoided. In vivo intra-arterial ultrasonic angioplasty of a canine chronic femoral fibrocellular occlusion was also performed. A preliminary in vivo study demonstrated feasibility of the percutaneous application of intra-arterial ultrasonic recanalization. Thus, ultrasonic energy appears to have potential as a method for ablation of occlusive atherosclerotic plaque.

Angiography↗
PubMed1991

Ultrasonic angioplasty in totally occluded peripheral arteries. Initial clinical, histological, and angiographic results.

BACKGROUND: Ultrasonic angioplasty was recently shown to ablate thrombi and atherosclerotic plaques in vitro and to recanalize occluded arteries in experimental animal models. The goal of the present study was to examine the clinical feasibility of ultrasonic angioplasty. METHODS AND RESULTS: Intraoperative ultrasonic angioplasty was performed in vivo on totally occluded peripheral arteries (n = 7). The ultrasonic angioplasty device consists of a 1.6-mm diameter flexible wire attached to a piezoelectric crystal generating ultrasound at 20 kHz. The controls, totally occluded human atherosclerotic femoral arterial segments (n = 6), were crossed mechanically with the ultrasound wire ex vivo but without application of ultrasonic energy. Ultrasonic angioplasty achieved successful recanalization without perforation in all vessels. Angiograms of the treated arteries showed an average lumen patency of 82.5%. Histological examination of the recanalized arteries revealed that the recanalization had taken place through intima diffusely involved with complicated plaque. The treated arteries, compared with the controls, had greater area of recanalized lumen (5.9 +/- 1.8 versus 1.7 +/- 0.4 mm2, p less than 0.05) and more flow (49.3 +/- 16.0 versus 11.8 +/- 4.9 ml/min, p less than 0.03). The damage in treated and control arteries was similar. Size-distribution analysis of the plaque debris from the treated arteries showed that 41 +/- 5% of the debris was 0.2-8 microns, 48 +/- 8% was 8-30 microns, and the remainder was 30-100 microns. In the mechanically crossed arteries, there was a shift in the distribution to larger size debris with 47 +/- 1% greater than 100 microns (p less than 0.001). CONCLUSIONS: Ultrasonic angioplasty may be a useful clinical method for recanalization of total occlusions in patients with peripheral vascular disease. Ultrasonic energy appears to cause controlled injury to the atherosclerotic intima by selectively disrupting the ultrasound-sensitive occlusion.

Aged↗