Piezoelectric Instrument Research Articles

Enamel Analysis by 3D Scanning after Three Orthodontic Clean-Up Procedures: An In-Vitro Test of a New Piezoelectric Tool.

(1) Background: To assess the clinical safety and efficacy of a new piezoelectric instrument for orthodontic clean-up; (2) Methods: An in-vitro comparative study on 75 teeth extracted for orthodontic reasons compared the tested method (Treatment 1) with two other procedures: One step finisher and polisher (Inverted cone One gloss Shofu Dental, Kyoto, Japan) (Treatment 2) and twelve-fluted tungsten carbide bur (123-603-00, Dentaurum, Pforzheim, Germany) and Sof-Lex discs Pop-On XT Kit (3M ESPE) (Treatment 3), with n:25 samples in each group. Clinical safety (enamel volume loss) and effectiveness (residual adhesive volume) were assessed using the structured light 3D scanner Atos Compact Scan (GOM GmbH) together with the support of Atos Professional software. The surfaces were scanned three times to assess: (i) the volume of the residual adhesive (RAV) after bracket removal; (ii) the volume of the relative residual adhesive (dAV) after the clean-up procedure; (iii) volume of the enamel loss (EVL); (3) Results: The mean RAV (mm3) was 0.239 ± 0.337; 0.069 ± 0.124, 0.120 ± 0.193 and the mean EVL (mm3) was 0.1870 ± 0.177, 0.187 ± 0.299 and 0.290 ± 0.205, for treatment 1, 2 and 3, respectively. The distribution was asymmetrical between groups in both cases; (4) Conclusions: The tested instrument proved to be effective and safe for post-orthodontic clean-up. With the increasing use of invisible aligners, the possibility of using an ergonomic and fast instrument is of benefit to both patient and practitioner.

Piezoelectric ear surgery: asystematic review. German version

The piezoelectric instrument (PEI) offers anovel technique for bone removal in ear surgery with acombination of micro-oscillation and cavitation. The aim of this review is to explore the advantages, disadvantages, and limitations of this instrument in comparison to the drill. We conducted asearch of PubMed/MEDLINE and Google Scholar in accordance with the PRISMA recommendations. The primary selection included all studies reporting on the use of PEI in ear surgery or its effect on the inner ear. Only studies with acontrol group were included in the secondary selection. The first search identified 49studies between 2003 and 2022. These reported on atotal of 1162ear operations, during which PEI was used for various indications. Most data were based on uncontrolled retrospective studies or case reports (76%). Only one of the five controlled clinical studies was prospective and randomized. The advantages of PEI weighed against its limitations and disadvantages were critically analyzed in comparison to the drill. Piezoelectric surgery is an innovative and promising surgical technique in the temporal bone. PEI appears to enable safer and more precise bone removal in close proximity to soft tissue when compared to the drill. The slower bone removal and cost factors represent current limitations to its wider use in ear surgery.

Orthodontics Surgical Assistance (Piezosurgery®): Experimental Evidence According to Clinical Results

Orthodontic tooth movement (OTM) is based on intermitted or continuous forces applied to teeth, changing the mechanical loading of the system and arousing a cellular response that leads to bone adaptation. The traditional orthodontic movement causes a remodeling of the alveolar bone and changes in the periodontal structures that lead to tooth movement. The use of a piezoelectric instrument in orthodontic surgery has already shown great advantages. The purpose of this study is to rank the behavior of inflammatory mediators in accelerating orthodontic tooth movement. Ten patients with malocclusion underwent orthodontic surgical treatment, which included a first stage of surgically guided orthodontic movement (monocortical tooth dislocation and ligament distraction, MTDLD) to accelerate orthodontic movements. In all cases, corticotomy was performed by Piezosurgery. Bone and dental biopsy was executed to evaluate changes in the cytokines IL-1beta, TNF-alpha and IL-2 in different time intervals (1, 2, 7, 14 and 28 days). The molecular mediators are IL-1 beta, TNF-alpha and IL-2. Immediately after the surgical procedure there was a mild expression of the three molecular markers, while the assertion of IL-1 beta and TNF-alpha reached the maximum value after 24 h and 48 h, indicating a strong activation of the treated tissues. The Piezosurgery® surgical technique induces an evident stress in short times, within 24–48 h from the treatment, but it decreases significantly during the follow-up.

Vibration energy harvesting on a drone quadcopter based on piezoelectric structures

The aim of this publication is to conclude on the interest of vibratory energy harvesting on classic quadcopter drone for autonomous applications (battery charging in real time, autonomous sensors), monitoring or even vibration control applications. A complete dynamic analysis allows to quantify the amount of electrical power that is possible to produce during the hovering flight of a quadcopter drone. These results have been obtained by substitution of the inert parts of the drone by piezoelectric components. For that purpose, different types of piezoelectric structures have been tested, including some commercial transducers (DuraAct from Piezoelectric Instrument and Murata buzzers) and some home-made such as a piezoelectric paint. Our original piezoelectric smart arms have been able to scavenge up to 5.35 mW during a stationary flight which remains quite enough to supply low-consumption sensors for monitoring applications.

Qualitative Evaluation of the Effects of Professional Oral Hygiene Instruments on Prosthetic Ceramic Surfaces

During professional hygiene procedures, different instruments used may cause various damage to dental prostheses. Deplaquing and scaling with curettes and ultrasonic instruments may inadvertently increase the surface roughness of the material and the risk of future bacterial adhesion and/or also compromise the marginal seal of the prosthesis. Hence, the aim of this study was to assess the qualitative effects of two types of curettes and one piezoelectric instrument with a stainless-steel tip on three types of metal-free samples. After treating the samples with different instrumentations, they were analyzed using the scanning electron microscope and then underwent a qualitative microanalysis by using a spectroscopy machine. All the materials tested in this study have undergone significant changes of their superficial structure after instrumentation both with mechanical and manual instruments. Plastic curettes appeared to be less aggressive than the other instruments. Disilicate samples show a significantly lower degree of surface glazing erosion compared to the zirconia sample with all the instruments used.

Topographic superficial craniectomy for invasive scalp carcinoma

The management of non-melanoma skin cancer of the scalp that invades the deep structures can be challenging. An operative technique of topographic superficial craniectomy using a piezoelectric instrument (Piezosurgery (Mectron S.p.A., Carasco, Italy)) for tumours with periosteal invasion without diploic space invasion is presented here. The tumour was resected including the periosteum of the craniectomy area. A grid was carved through the outer table using the Piezosurgery device. The grid squares measured approximately 1.5 cm on each side. A bony strip was removed from one side of the grid to complete a deep cut while avoiding crossing the inner table. The squares were collected individually with a chisel and sent for pathological analysis. This technique was used to identify and localize any possible bone invasion. As this method allowed an accurate pathological diagnosis to be obtained from the Piezosurgery squares, it was possible to determine the appropriate adjuvant treatment, thereby reducing the risk of malignant cells spreading.

Piezoelectric canalplasty for exostoses and osteoma

ObjectiveTo evaluate the safety profile and surgical technique for removal of symptomatic exostoses and osteoma of the external auditory canal with a micro-oscillating piezoelectric device. MethodA chart review was conducted on patients undergoing piezoelectric canalplasty between 2019 and 2021 at tertiary referral hospital. Surgery was performed by two surgeons with varying experience. Bone removal was achieved using both osteotomy and osteoplasty. Postoperative complications, operative time and hearing outcome were evaluated. ResultsThe study comprised 16 patients (16 ears). No major complications occurred. The skin of the auditory canal was completely preserved in all patients without injury to the tympanic membrane. Except for one patient with known noise-induced hearing loss, there was no postoperative deterioration of the bone-conduction threshold more than 10 dB HL at any frequency. The difference of the bone-conduction threshold in pure-tone audiometry (average for 0.5, 1, 2 and 4 kHz) three weeks postoperatively had a median of 0.6 dB ± 5.7. One patient complained of temporary new tinnitus. One patient had prolonged wound healing. Mean operative time was comparable with literature data. ConclusionThe atraumatic characteristics of the piezoelectric instrument enable low-risk removal of external auditory canal exostoses and osteoma. Through the combination of precise osteotomy and osteoplasty, this novel instrument has the potential to become established in routine canalplasty.

Cervical ventral slot in rabbits (Oryctolagus cuniculus). Piezosurgery versus conventional technique.

ABSTRACTPurposeTo investigate the applicability of piezosurgery for cervical ventral slot (CVS), comparing it with the conventional technique of using high-speed burs for bone wear.MethodsThirty rabbits (Oryctolagus cuniculus) were divided into two treatment groups (T1 and T2) corresponding to CVS between C3-C4. In T1, the surgery was performed with piezoelectric apparatus, and in T2 with high-speed burs. The evaluated parameters were: duration of each stage of surgery, temperature variations during CVS, visibility of the surgical field, intra and postoperative complications, and anesthetic monitoring. At 14, 28, and 56 postoperative days, five animals from each treatment group were submitted for histopathological study of the surgical site.ResultsCompared with T2, T1 had more precise bone cut, and better visibility of the operative field, although it required longer total surgical time (p = 0.02) and triggered a greater number of intraoperative complications (p < 0.01), microscopic lesions in the spinal cord (p < 0.05), and transient neurological deficits in the postoperatively (p < 0.05).ConclusionsIt is necessary to perform surgical planning and have several tips of the piezoelectric instrument available for the safe use of the piezoelectric device in neurosurgery.

Quantifying Aerosolization of Facial Plastic Surgery Procedures in the COVID-19 Era: Safety and Particle Generation in Craniomaxillofacial Trauma and Rhinoplasty.

Background: COVID-19 poses a potentially significant infectious risk during procedures of the head and neck due to high viral loads in the nasal cavity and nasopharynx. Facial plastic surgery has significant exposure to these areas during craniomaxillofacial trauma procedures and rhinoplasty. Methods: Airborne particulate generation in the 1-10 μm range was quantified with an optical particle sizer in real time during cadaveric-simulated rhinoplasty and facial trauma conditions. Procedures tested included mandibular plate screw drilling, calvarial drilling, nasal bone osteotomy, nasal dorsal rasping, and piezoelectric saw use. Particulate generation was measured both adjacent to the surgical site and at surgeon mouth level (SML). Results: Mandibular plate screw drilling without irrigation generated significant particulate both adjacent to the surgical site and at SML (p < 0.01). Irrigation mitigated particulate generation at SML to nonsignificant levels. Calvarial drilling additionally produced substantial particulate above baseline adjacent to the surgical site (p < 0.01). Standard nasal osteotomies and dorsal rasping did not generate detectable airborne particulate, whereas piezoelectric saw use was associated with significant particulate generation both adjacent to the surgical site (p < 0.001) and at SML (p < 0.01). At SML, smaller particulate represented a significantly higher proportion of total particulate detected. Conclusions: The majority of craniomaxillofacial trauma procedures involve particle generation that may be limited in spread by the use of local irrigation. Most bony work involved in rhinoplasty can be safely performed without a high degree of particle formation. The use of piezoelectric instruments in rhinoplasty should be avoided when concerned for particulate generation.

Pulp vitality during ultrasonic tooth preparation. Part 2.

Ultrasonic devices have a lot of dental application specially in hygiene and surgery. However there are some disadvantages like cut slowness and heat production. Prosthodontics application is less investigated. In particular the heat production could be an important factor for the clinician. In fact more than 5.5 °C temperature increasing could determine pulp necrosis during tooth preparation. The aim of this study is to investigate the increasing of temperature during finishing line repositioning and polishing phases using ultrasounds inserts and to verify if it remains within the limit of 5.5 °C. A sample of 32 human molars (extracted for periodontal reasons) was selected. The teeth were endodontically treated and prepared with burs in order to obtain a prosthetic round chamfer preparation, leaving the apical portion pervious for inserting the thermocouple probe. Then, they were inserted in plaster cubes up to the cement-enamel junction. A wall has been selected for each tooth for margin repositioning and finishing and prepared with the piezoelectric instrument (Multipiezo Touch with TipHolder DB2, Mectron, Carasco, Genoa, Italy). A mechanical arm was used to standardize the operator-dependent parameters. These parameters were: the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. The test phase consisted in a first stage of margin repositioning using an regular ultrasound tip with a diamond grain of 120 micron (DB120, Mectron, Carasco, Italy) (group 1), followed by a second finishing step conducted by a extra fine ultrasound tip with a diamond grain of 60 micron (DB60, Mectron, Carasco, Italy) (group 2). Each test lasted 60 seconds: this was the time that the mechanical arm needed to accomplish 32 rides. During these stages the intrapulpal temperature has been recorded thanks to a thermocouple. The obtained temperature data were analyzed by Kruskal-Wallis test and Mann-Withney post-hoc test, without Bonferroni correction (P<0.001). The average pulpal temperature increase was 4.65 °C with a standard deviation of 0.99 °C for the DB 120 ultrasonic tip and 5.40 °C with a standard deviation of 0.84 °C for the DB 60 ultrasonic tip. However, neither of the instruments reach the medium critical level of 5.5°C reported in the literature, there are some single values who exceed it. There is statistically significant difference using tips with different granulometries within the two groups (P value =0.013). Ultrasonic tools are very performing to achieve results in repositioning and polishing of prepared tooth. The in-vitro analysis show that the pulp temperature increasing remains within the safe limits literature shows. It is important underline the polishing phase is the most critical and the clinicians have to pay attention to irrigation and pression to avoid pulp damages. Additional clinical studies have to be performed to confirm these results.

Temperature variations in pulp chamber: an in-vitro comparison between ultrasonic and rotating instruments in tooth preparation. Part 1.

The purpose of this study was to analyze pulpal temperature increase generated by prosthodontic margin repositioning and finishing with ultrasonic and rotating instruments. The temperature changes recorded were also correlated with the residual dentin thickness. A sample of 32 human extracted molars was selected. The teeth were endodontically treated and prepared with prosthetic round chamfer preparation. Then, they were inserted in plaster cubes up to the cement-enamel junction, leaving the apical portion pervious for inserting the thermocouple probe. The conventional technique, which involves the use of a high-speed contra-angle handpiece, was compared with an ultrasonic method (Crown Prep, Mectron, Carasco, Italy). For margin repositioning and finishing, two walls were randomly selected for each tooth: one was included in the test group and cut with the piezoelectric instrument (Multipiezo Touch TipHolder DB2, Mectron, Carasco, Genoa, Italy), the other one was inserted in the control group and cut with the high speed contra-angle handpiece (Kavo, Biberach, Germany). To standardize the operator-dependent parameters, it was used a mechanical arm controlled by a computer. These parameters were the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. For both test and control group, test phase consisted in a first stage of margin repositioning using an ultrasound tip or a diamond bur with a greater granulometry (120 µm for the ultrasound tip and 125 µm for the diamond bur), followed by a second finishing step conducted by an ultrasound tip or a diamond bur with smaller granulometry (60 µm for the ultrasound tip and 30 µm for the diamond bur). During these stages the intrapulpal temperature was recorded thanks to a thermocouple. Before and after these steps, the thickness of the remaining dental walls was measured with a caliber. The average pulpal temperature increase was 5.03±0.98 °C for the ultrasonic preparation (test group) and 3.55±0.95 °C for the conventional technique (control group). The difference was statistically significant (P value <0.001). However, neither of the instruments reached the critical level of 5.5 °C reported in the literature. The mean initial dentin thicknesses was 1.82±0.47 mm for the control group and 1.59±0.54 mm for the test group but the analysis of the residual dentin thicknesses revealed a greater reduction of the walls worked up with high speed contra-angle handpiece (mean 0.9±0.5 mm), which was therefore more aggressive than the ultrasonic instrument (mean 1.1±0.5 mm). A very weak negative correlation was present between the thickness of the wall at baseline and the increment of temperature. Within limitations of this study, temperature increasing of ultrasonic instruments shows a statistical difference related to rotary ones. But, as literature shows, the ultrasonic advantages are margin precision, preservation of soft tissues and reduction of operating times. Furthermore, in relation with results of this study, they could be considered safe for pulp vitality because the increase in pulpal temperature is similar to traditional instruments and it does not exceed the critical level of 5.5 °C.

Piezosurgery: Ten Years' Experience of Percutaneous Osteotomies in Rhinoplasty

The possibility to obtain precise osteotomies without major soft tissue damage represents a key point in modern approaches to rhinoplasty. In 2007, the authors first described their ultrasonic approach for percutaneous nasal bone osteotomies with minimal periosteal detachment. In this article, they retrospectively analyze the results of their piezo-surgical rhinoplasty technique through their 10-year experience and describe new perspectives of this technique. A series of 183 patients was retrospectively evaluated. Surgical technique was based on piezoelectric external nasal osteotomies, performed percutaneously, without periosteal detachment. For the last patients, the piezoelectric instrument also was tracked with a navigator (piezo-navigated approach). Data on surgery, hospitalization, ecchymosis, edema, and postoperative complications were evaluated. Of the 183 patients, 168 (91.8%) showed grade 0 or 1 edema. Grade 2 edema was noticed in only 15 of 183 patients (8.2%). In 6 of the 183 procedures (3.3%), postoperative complications potentially related to the piezoelectric osteotomy system occurred. The piezoelectric external approach can be considered a safe and reliable technique. Preliminary data suggest the possibility of using surgical planning and navigation in positioning the osteotomies in selected subsets of patients.

Usage of piezoelectric instruments in larynx surgery.

The aim of the study was to estimate usability of the piezoelectric knife in larynx surgery. Prove that the piezoelectric staff can be used to do any different shape incision within the larynx cartilages. 35 patients hospitalized in our Department in 2014-2016 were enrolled in our study. 24 patients went vertical partial laryngectomy and 1 patient went horizontal partial laryngectomy because of larynx cancer. 5 patients went partial laryngectomy because of low stage of piriformis recess cancer. Piezoelectric staff was used to do thyroidectomy and resection of thyroid cartilage suspected of carcinomatosis infiltration. The rest 4 patients had done widening of larynx lumen due to larynx stenosis or slenderness. The piezoelectric tool was used to do different incision or resection within the larynx cartilages in case of widening lumen of the larynx. The larynx cartilages, especially thyroid cartilage could be cut in different shapes using piezoelectric tools. The usage of this equipment causes the minimal loss and small destruction of local healthy tissues. The Piezoelectric instrument is useful instrument suit to operate within larynx cartilages. Exchangeable tip available in different shapes enables different resections of cartilages. Using the piezoelectric staff we can remove pathological tissue with minimal local destruction. Our observation shows that larynx operation with a usage of the piezoelectric knife is safe and effective. Current English literature does not describe usage piezoelectric tools in larynx surgery. It is essential to do more observation about that type of operations.

Effect of Piezoelectric Sutural Ostectomies on Accelerated Bone-Borne Sutural Expansion

The present study investigated the effect of piezoelectric sutural ostectomies on accelerated bone-borne sutural expansion. Sixteen male New Zealand white rabbits (20 to 24weeks old) were randomly divided into 4 experimental groups (n=4): group 1, conventional rapid sutural expansion; group 2, accelerated sutural expansion; group 3, accelerated sutural expansion with continuous ostectomy; and group 4, accelerated sutural expansion with discontinuous ostectomy. All sutural ostectomies were performed using a piezoelectric instrument (Woodpecker DTE, DS-II, Guangxi, China) before expander application with the rabbits under anesthesia. Modified hyrax expanders were placed across the midsagittal sutures of the rabbits and secured with miniscrew implants located bilaterally in the frontal bone. The hyrax expanders were activated 0.5mm/day for 12days (group 1) or with a 2.5-mm initial expansion, followed by 0.5mm/day for 7days (groups 2 to 4). After 6weeks of retention, the bone volume fraction, sutural separation, and new bone formation were evaluated using micro-computed tomography and histomorphometry. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U tests and Spearman's rho correlation (P<.05). Ranking of the median sutural separation was as follows: group 1, 3.05mm; group 2, 3.97mm; group 4, 4.78mm; and group 3, 5.66mm. The least and most bone formation were observed in groups 1 (63.63%) and 3 (75.93%), respectively. Spearman's correlation showed a strong, positive, and significant correlation (r=0.932; P<.01) between the new sutural bone formation and amount of sutural separation. Piezoelectric sutural ostectomies increased the rate of sutural separation and promoted new sutural bone formation/osteogenesis. Continuous ostectomy gave better results than discontinuous ostectomy.

Piezoelectric Surgery –A Novel Technique for Laminectomy

ABSTRACTObjective: Piezoelectric surgery is a novel technology that allows for the osteotomy of mineralized tissue with less risk of damaging underlying soft tissue structures. This selective cutting increases the safety of osteotomies performed in close vicinity to delicate structures such as dura mater, blood vessels, and neural tissue. This study aimed to develop and describe the technique of piezoelectric surgery for dorsal laminectomy and to assess its clinical safety in normal sheep. Methods: A piezoelectric, dorsal laminectomy technique was developed using ovine cadavers. Following technique development, six live sheep underwent a piezoelectric (n = 6) two-level dorsal laminectomy at L2-L3 and L4-L5 (PiezoL2-3,4-5), and another 30 live sheep underwent a three-level laminectomy at L1, L3, and L5 (PiezoL1,3,5) for a total of 102 laminectomy sites. Surgery time and postoperative complications were recorded. Results: Dorsal laminectomy was safely and accurately performed in 35/36 study sheep using a Piezoelectric surgical instrument. No dural tears were noted in any animal. Non-ambulatory paraparesis in one study sheep (PiezoL1,3,5) led to euthanasia at 48 hr and only mild epidural hematoma was noted on necropsy. No other major postoperative complications were observed in any of the animals. Subjectively, PiezoL was easy to perform and with a rapid learning curve. Mean surgery time was 105 min (range: 75–165 min; median: 97.5) for PiezoL2-3,4-5 and 93 minutes (range 55–100 min; median: 67.5) for PiezoL1,3,5. Conclusions: Based on our study, PiezoL is considered a safe and viable technique for performing ovine dorsal laminectomy in the preclinical research setting.

Use of an ex vivo canine ventral slot model to test the efficacy of a piezoelectric cutting tool for decompressive spinal surgery

AbstractObjectiveTo test the efficacy of a piezoelectric instrument (PI) for bone removal during ventral slot surgery.Study DesignEx vivo feasibility study.Sample PopulationCadaveric canine cervical spinal specimens (n = 3; C1–7; C1–T1; C2–T1).MethodsThe spinal cord of each explanted spinal unit was replaced with a saline‐filled latex condom. In 8 disc spaces, ventral slot surgery was performed using a previously reported technique. Bone removal was achieved using a motorized burr (MB). In 8 disc spaces, bone was removed via en bloc ostectomy with a PI that selectively cuts mineralized tissue. Surgical duration and operating field visibility were recorded. Rupture of the fluid filled condom was used as a measure of iatrogenic collateral trauma. Computed tomography was used to measure ventral slot morphometry.ResultsMean surgical duration for PI (23.4 minutes) was significantly shorter than for MB (34.1 minutes; P = .049). Using a 4 point Likert scale (4 = excellent, 3 = good, 2 = fair, 1 = poor), median visibility score was significantly higher for PI (2) than for MB (1; P = .03). The condom burst twice (1MB, 1PI) during elevation of the dorsal longitudinal ligament; there was no significant difference between techniques for incidence of collateral trauma (P = .99). Regardless of surgical technique, there was a bias in slot deviation towards the right (i.e., the surgeon's left; P = .021).ConclusionsThe PI allowed completion of ventral slots in a significantly shorter time, without an increased incidence of iatrogenic trauma. The right‐handed surgeon showed a left‐sided aiming bias, regardless of surgical technique.

Measurement of two-dimensional Doppler wind fields using a field widened Michelson interferometer

An implementation of the field widened Michelson concept has been applied to obtain high resolution two-dimensional (2D) images of low velocity (<50 m/s) Doppler wind fields in the lab. Procedures and techniques have been developed that allow Doppler wind and irradiance measurements to be determined on a bin by bin basis with an accuracy of less than 2.5 m/s from CCD images over the observed field of view. The interferometer scanning mirror position is controlled to subangstrom precision with subnanometer repeatability using the multi-application low-voltage piezoelectric instrument control electronics developed by COM DEV Ltd.; it is the first implementation of this system as a phase stepping Michelson. In this paper the calibration and characterization of the Doppler imaging system is described and the planned implementation of this new technique for imaging 2D wind and irradiance fields using the earth's airglow is introduced. Observations of Doppler winds produced by a rotating wheel are reported and shown to be of sufficient precision for buoyancy wave observations in airglow in the mesopause region of the terrestrial atmosphere.

Relative Contribution of Patient‐, Tooth‐, and Site‐Associated Variability on the Clinical Outcomes of Subgingival Debridement. I. Probing Depths

The objective of this clinical trial was to assess the relative contribution of patient-, tooth-, and site-associated variables on changes in probing depths (PD) following delivery of a standard non-surgical phase of periodontal therapy. Ninety-four (94) systemically healthy subjects with severe generalized periodontitis were included in this 6-month prospective longitudinal study. Medical, periodontal, and microbiological parameters were collected at baseline and 2 and 6 months after completion of oral hygiene instructions, motivation, and subgingival debridement using a piezoelectric instrument. The relative contribution of patient-, tooth-, and site-associated variables was evaluated with a hierarchical multilevel analysis. Eighty percent (80%) of variability in PD reductions was attributed to site level parameters, while 12% was at the tooth level and 8% at the patient level. The multilevel analysis associated PD reductions with patient factors (cigarette smoking status and carriage of the rare allele of a specific polymorphism for the interleukin-6 [IL-6] gene), tooth factors (tooth mobility and tooth type), and site factors (mesial and distal location). Cigarette smoking and carriage of the rare allele of the IL- 6-174 G/C polymorphism were associated with less PD reduction. Incisors and canines responded better than premolars and molars. A dose-dependent effect of mobility was observed: teeth with higher baseline mobility resulted in significantly greater decreases in PD. At the site level, greater reductions were observed at interdental sites (compared to facial or oral), and at deeper sites (1.2 mm for 4 to 5 mm pockets and 2.4 mm for pockets > or =6 mm). These data provided an estimation of the relative contribution of site-, tooth-, and patient-associated variables in terms of PD reductions following a standard course of machine-driven subgingival debridement.

Piezoelectric Rotary Vibrator (PRV) – a new oscillating rheometer for linear viscoelasticity

Conventional, motor controlled rheometers, allow, e.g., stress-controlled measurements of the shear viscosity up to several thousands in shear rate, but reliable oscillating viscoelastic measurements only up to f=50 Hz (ω=300 s–1). This limitation is overcome – even if only for linear viscoelasticity – by a new piezoelectric instrument oscillating in rotary mode (PRV), covering the frequency range from 0.5 Hz up to 2 kHz , and bridging the gap to resonator methods.

Piezoelectric non-resonant transformer to measure high voltage

The present paper is based on the research activity carried out at the Polytechnic University of Catalunya on the development of a new instrument transformer to measure voltages in distributing networks. This novel instrument transformer is presented as a future alternative to the classical electromagnetic instrument transformer. Such a solution uses piezoelectric materials working in non-resonance to perform the transformation from high voltage to low voltage. The configuration of piezoelectric instrument transformer of two columns (actuator and sensor columns) was chosen to perform the research. Mechanical, electrical and thermal limits were clearly defined to select the appropriate materials and to determinate the lines of the design to obtain a reliable and precise device.