Piezoelectric Tip Research Articles

HISTOMORPHOMETRIC AND IMMUNOHISTOCHEMICAL EVALUATION OF BONE HEALING AROUND IMPLANTS PLACED USING PIEZOSURGERY VS CONVENTIONAL DRILLS: A SPLITMOUTH PILOT STUDY.

This pilot study evaluated and compared histomorphometric and immunohistochemical characteristics of peri-implant bone tissue after implant site preparation using piezoelectric tips versus conventional drills. Six patients with bilateral partial edentulism underwent a splitmouth protocol. Twelve alveolar ridges were randomized into six control implant sites prepared using conventional drills (Drill Group); and six test implant sites prepared using piezoelectric implant inserts (Piezo Group). At 28 days after surgery (T1), single-stage "study fixtures" with 0.5 mm of peri-implantbone tissue were explanted and processed for histological, histomorphometric and immunohistochemical analysis in both groups. For each sample inflammatory infiltrates, necrotic bone (Zone 1), woven and newly formed bone (Zone 2), native bone (Zone 3), a vascular endothelium differentiation and neo-osteogenesis marker (CD31) and an osteoblastic cell differentiation and osteogenesis marker (SATB2) were evaluated. According to their histological bone features, the three histologically distinct areas were evident in both groups: Zone 1, Zone 2 and Zone 3 according to their histological bone features. Zone 1 showed lower extension in the Piezo Group than in the Drill Group (p=0.028). Regarding the immunohistochemical markers, in all areas of the Piezo Group, SATB2 and CD31 were statistically higher than in the Drill Group. Implant site preparation using piezo surgery results in less bone necrosis, greater osteoblastic activity and greater vessel proliferation compared to the conventional surgical approach.

Evaluation of patient comfort and satisfaction after the surgical removal of mandibular impacted molars using a piezo-electric technique: A randomized double-blind clinical trial.

This is a double clinical trial conducted to study the patient satisfaction and comfort during and after surgical removal of impacted mandibular 3rd molar using Piezo electric tips. Two groups of 25 each [14 (56%) males and 11 (44%) females] and [18 (72% males and 07 (28%) females] represented the Rotary and Piezo groups respectively with bilateral impactions. one side of the patient is operated by piezo and the other side by rotary instrument after a gap of 2-3 week between the procedures. The variables considered are pain, swelling, trismus, patient satisfaction and comfort. The readings were taken on base line,3rd day,7th and 14th day. Descriptive statistical analysis was performed using means and standard deviations for continuous variables and percentages for categorical variables. The level of significance was set at p<0.05. The surgery time taken was more in the Piezo group (26.96±12.201) in comparison with the Rotary group (21.32±12.786- (p=0.011∗). Satisfaction was rated better in the Piezo group (3.18±0.909 vs 2.88±0.881) (p=0.013∗). Tactile sensation was less in the Piezo group (1.24±0.436) vs (2.28±0.678) (p=0.001). Less pain was reported in the piezo group patients and the difference between the two groups was statistically significant only during the third day follow up (p=0.001). The overall patient satisfaction and comfort was better in piezo in spite of longer duration of surgery. It provides better quality of life as the patients experienced less pain and the total number of analgesics taken is significantly less compared to rotary group.

Evaluation of Modified Shell Technique in 3D Ridge Reconstruction: A Clinical and Radiographic Study

Introduction: As a result of tooth loss, alveolar ridge resorption sacrifices bone volume including bone width. In order to replace the lost dentition with implants functionally and esthetically, bone augmentation procedures are carried out. Materials and Methods: Fifteen patients were selected to treat mandibular alveolar ridge resorption with an autogenous block graft harvested using piezoelectric surgical tips and split into two shells using a diamond disk then fixated on the decorticated defective ridge. Particulate xenograft bovine bone was then inserted between the fixated shell and ridge, the second shell was used to roof the bone particles. Results: The modified shell technique could be an alternative to other ridge augmentation techniques. This study shows promising clinical and radiographic results that carry the advantages of being: safe and precise cutting using Piezoelectric tips, the statistical data showed a significant difference in 3D bone volume where no unfavorable complication was detected. Conclusion: The modified shell technique showed a reliable technique in cases of 3D ridge reconstruction since it holds the advantages of autogenous bone properties and the rigidity of the bone shells that maintain the space necessary for augmentation. The use of PRF can accelerate wound healing and minimize the risk of flap dehiscence as well as it can speed up bone formation.

Surface Roughness of Enamel and Dentin after Preparation Finishing with Rotary Burs or Piezoelectric Instruments

This study compares the effect of different handpieces (turbine, high-speed electric handpiece and piezoelectric device) on surface roughness of enamel and dentin when using diamond-coated working tips and burs of the same grit size. The experiment was conducted on 15 extracted first molars from patients aged 45 to 60 years. The occlusal portion was removed using a diamond-coated water wheel and then refined with a 120–130 μm grit bur in order to obtain a flat surface with an adequate exposition of the dentin core. Each surface was divided into three portions and every portion was finished with one of the three tested instruments. The rotary burs and piezoelectric tips had the same grit size (60 μm), and the load on handpiece during preparation never exceeded 150 g. Roughness parameters (Ra, Rsk, Rku) were recorded with a profilometer, and a SEM analysis of treated surfaces and working tips was conducted. Ra and Rsk differed significantly between enamel and dentin only after using turbine (p = 0.004 and p = 0.007, respectively). No significant differences were observed in Ra, Rsk and Rku between enamel and dentin when using a high-speed electric handpiece or piezoelectric device. The turbine produced higher Ra and Rsk values on dentin than the other devices, while no significant differences were found between piezoelectric handpiece and high-speed electric contra-angle on both substrates. Summarizing, the findings of the present study demonstrated that turbine generated rougher surfaces on dentin compared to the other handpieces. Moreover, the turbine produced more asymmetrical surface profiles on both enamel and dentin. However, it should be considered that these differences in roughness (Ra) were within the range of 0.25–0.30 μm: it is still unclear if these variations, although statistically significant, will influence final clinical outcomes.

Minimally Invasive Aesthetic Crown Lengthening: A Piezoelectric Assisted Case Series with 4-Year Follow-Up

Aim: This retrospective study aims to reveal the clinical outcome at 48 months of a minimally invasive crown lengthening technique performing an intrasurcular flapless osteotomy, using a piezoelectric tip designed for this purpose. Material and Methods: All subjects in the current case series required esthetic crown lengthening procedures in the anterior esthetic zone of the maxilla. Prosthetic planning was carried out, which included a digital waxup of the ideal tooth morphology, which allowed constructing a surgical guide to transfer the proposed gingival margins to the patient. Gingivectomy was performed by using an electrosurgery system Perfect TCS IITM (Coltene Whaledent) and osteotomy by using a piezoelectric insert PiezoSmileTM (BROK) until achieving a bone crestgingival margin distance similar to the presurgical. Results: 57 patients were followed postoperatively for 48 months. During the post-operative period, healing, complications, periodontal and aesthetic health parameters including the position of the gingival margin were observed. WES, PES and RES indexes showed an optimal integration with the restorative materials and a good aesthetic result. Conclusion: Minimally invasive crown lengthening technique with electrosurgery and a piezoelectric insert is effective in repositioning the gingival margin in a stable and predictable manner within a 48 months follow-up.

In Vitro Qualitative Evaluation of Root-End Preparation Performed by Piezoelectric Instruments.

Although the application of ultrasounds in endodontic surgery allows for effective debridement of the root canal, incorrect device setting or inefficient tips seem to generate cracks during root-end retropreparation. The primary aim of this in vitro study was to establish the presence, or absence, of a correlation between ultrasonic root-end preparation and the formation of cracks. The present study was conducted on human teeth, extracted for periodontal reasons. After root canal treatment, roots were resected 3 mm from the anatomical apex by using a high-speed handpiece and carbide burs. The resected teeth were retroprepared by using an ultrasonic tip (R1D, Piezomed, W&H, Bürmoos, Austria), setting the piezoelectric device at maximum power available for the tip. Time required for the retropreparation was recorded. Before and after retropreparation, all roots were photographed under a stereomicroscope and analyzed by two different operators to evaluate: (a) the presence and extension of dentinal cracks and (b) the morphology of root-end preparation. Finally, piezoelectric tips were analyzed by scanning electron microscopy (SEM) to evaluate morphologic changes after use. A total of 43 single roots (33 with one root canal, 10 with two root canals) were treated. Average preparation time was 1 minute and 54 seconds. None of the roots without initial cracks developed new cracks after retropreparation. Quality of the preparation margins was fairly equal among the prepared specimens. None of the piezoelectric tips broke during instrumentation, and SEM analysis showed minimal surface wear of the tips after performing 11 retropreparations. Within the limits of the present study, the tested piezoelectric system does not seem to represent a major cause for root crack formation. Pre-existing cracks may expand after ultrasound root-end preparation.

In vitro comparison of root surface roughness and bacterial adhesion following treatment with three different instruments.

A novel device, piezoelectric 11 Gracey curet tip, reportedly combines benefits of a piezoelectric device and manual curet. The primary objective of this study was to compare root surface roughness outcomes between traditional manual curets and piezoelectric devices, as compared with this novel device. The secondary aim was to assess the level of adhesion of Streptococcus mutans on the root surface after instrumentation. The groups consisted of the following: 1) Gracey curet; 2) piezoelectric scaler; 3) piezoelectric 11 Gracey curet tip; and 4) untreated control. Root specimens were obtained from extracted human teeth and randomly assigned to each group. Surface roughness measurements (Ra and Rz) were taken with a profilometer before and after instrumentation. After instrumentation, root specimens were inoculated with S. mutans and biofilm was dislodged. Various dilutions of resuspended biofilm were incubated on blood agar plates and colony forming units (CFU) values were measured. The experimental device resulted in significantly lower Ra and Rz compared with other groups (P<0.01), and the Gracey curet was significantly lower than the piezoelectric tip and untreated control (P<0.05). The Gracey curet and experimental device tip had significantly lower CFU values compared with the control (P<0.05). There were no significant CFU value differences between the Gracey curet and both the piezoelectric and experimental device tips. There were no significant CFU differences between piezoelectric tip and both experimental device and control. There was no correlation between Ra and CFU values for Gracey curet, piezoelectric tip, or the control. However, correlation between Ra values and CFU approached significance for the experimental device (correlation=0.66, P=0.05). Piezoelectric 11 Gracey curet tip is effective at resulting in a significantly smoother surface compared with traditional piezoelectric and hand instruments. CFU values with piezoelectric 11 Gracey curet tip were significantly lower than non-instrumented surfaces, but there were no significant differences compared with conventional methods.

Peri-Implant Bone Damage Procured by Piezoelectric and Conventional Implant Site Preparation: An In Vitro Comparison

Background: The conventional drill technique is the most commonly used for the implant site preparation of the desired diameter and length. Ultrasonic implant site preparation (UISP) can also be used to perform an implant site preparation of the desired dimensions. Methods: Implant sites were prepared in fresh bone ribs with two different implant site preparation techniques: implant surgical drills and piezoelectric tips. Samples were analyzed with scanning electron microscopy (SEM) for evaluating the peri-implant bone damage. Result: In the surgical drills group, the cortical bone surface showed several cracks and the bone vascular canals were hidden by a dense smear layer. Cancellous bone showed large irregularities and trabecular fractures. The piezoelectric group showed a clean and smooth cortical bone surface with opened bone vascular canals; the cancellous bone presented a regular morphology, and the trabecular spaces, clearly visible, were free of debris. Conclusions: Ultrasonic implant site preparation showed cleaner bone surfaces and lower bone trauma compared with the preparation using implant surgical drills.

Piezoelectric Implant Site Preparation: Influence of Handpiece Movements on Temperature Elevation.

Piezoelectric devices are widely used in oral surgical procedures, including implant site preparation. However, little is known about the influence of working movement on temperature elevation in bone. The aim of this study was to assess the effects of two different working cycles on temperature elevation during piezoelectric implant site preparation. Sixty osteotomies at a depth of 10 mm were performed on bone blocks of bovine ribs using a piezoelectric tip with external irrigation (IM1s, Mectron Medical Technology, Carasco, Italy). A mechanical positioning device was used to guarantee reproducible working and measuring conditions. Two different working cycles, of 4 and 6 s, respectively, were tested, including both longitudinal and rotational movements. Temperature was recorded in real time with a fiber optic thermometer and applied pressure was maintained under 150 g. For each test, the highest recorded temperature (Tmax) and the mean temperature recorded from 30 s before to 30 s after the highest recorded temperature (T±30) were extrapolated. Tests duration was also recorded. Both Tmax and T±30 were significantly higher in the ‘6 s cycles’ group than the ‘4 s cycles’ group (42.44 ± 7.3 °C vs. 37.24 ± 4.6 °C, p = 0.002; 37.24 ± 4.6 °C vs. 33.30 ± 3.3 °C, p = 0.003). Test duration was also significantly higher using 6 s cycles compared to 4 s cycles (143.17 ± 29.4 s vs. 119.80 ± 36.4 s, p = 0.002). The results of this study indicate that working cycles of 4 s effectively reduce heat generation and working time during piezoelectric implant site preparation.

EVALUATION OF BUCCAL BONE LID TECHNIQUE USING PIEZOELECTRIC SURGERY IN SURGICAL EXTRACTION OF DEEPLY IMPACTED LOWER THIRD MOLAR (A CLINICAL AND RADIOGRAPHIC STUDY)

Introduction: Surgical removal of deeply impacted third molar is complicated most times with inferior alveolar nerve injury and developing large bony defects because of the deep situation of impacted tooth and limited visibility. Buccal bone lid technique using the piezoelectric device is a recent technique for surgical removal of such an impacted tooth to avoid these complications. As it allows accessibility and the accuracy of piezoelectric tips to cut through bone only without damaging adjacent tissues. Objectives: The main aim of this study was to evaluate the efficiency of buccal lid technique using piezotome surgery in removal of deeply impacted third molar. Materials and methods: Ten patients with deeply impacted lower third molar were subjected to surgical extraction using buccal lid technique. Clinical follow up was conducted after a 24-hours, 72-hours, one week, six months. Also, a radiographic investigation was performed immediately postoperative and after six months to estimate the mean bone density at the buccal bone. Results: By the end of the follow- up period, all cases showed normal lower lip sensation, the decrease in level of pain intensity score based on the Visual Analogue Scale (VAS) and an uneventful wound healing with no records of developed infection. Mean bone density after six months showed a statistically significant change in buccal bone density (p 0.005). Conclusion: This study deduced that the use of buccal lid technique in extraction of mandibular bony impacted wisdom results in a predictable and satisfactory outcome, to achieve inferior alveolar nerve preservation and reduce bone defect.

Triangular Separation Distance Effects on Wave Electrical Energy Harvester Performance

Energy scavenging has become a topic of interest toward green and environmentally friendly. Vortex generated in the wake region behind a bluff body is potential to be harvested and transform the mechanical vortices into electrical energy. Therefore, the study of the fluid flow and piezoelectric material is highly potent and a promising research area. Thus, the vortex-induced vibration (VIV) energy harvesting of two bluff bodies in a tandem arrangement is investigated using the 3D simulation. There are four sets of bluff bodies with various distance ratio, x/D from 3 to 6, were analyzed in this simulation. The coupling analysis was analyzed using ANSYS Transient Structural and computational fluid dynamic Fluent module. The triangular width, to 100 mm and the fluid average flow velocity is 1.46 ms−1, which corresponds to Reynold number (Re) of 10k. Four types of analysis have, out; velocity vector, turbulence kinetic energy, piezoelectric tip deformation, and generated output voltage. The results show the bluff shape with spacing ratio 6 has better vortex shedding formation and turbulence kinetic energy formed on both upstream and downstream triangular bluff body. The tips mesh displacement for piezoelectric is highest at space ratio 6 with 7.0 x 10−5 essential, and after 10s the beam deflection is continuing at around 1 x 10−5 m. While the voltage generated is, at spacing ratio 6 with 0.2 v produced. The obtained results are essential to VIV analysis of the dual triangular cylinder with piezoelectric film, which is vital in energy scavenging knowledge.

Residents' journal review

Residents' journal review

Osteotomy speed, heat development, and bone structure influence by various piezoelectric systems-an in vitro study.

The aim of this in vitro study was to evaluate osteotomy speed, heat development, and bone structure influence from osteotomies performed by various piezoelectric devices and insert tips. These devices and tips were compared among each other with regard to conventional rotatory and oscillating systems with special focus on the insert tip design and thickness. The osteotomies were conducted on porcine ribs utilizing 12 different insert tips (straight and angulated) and three conventional systems. After time and temperature measurements, histological analysis was carried out. Light microscopy was used to evaluate the roughness of the osteotomic surface and to search for indications of thermal bone necrosis. A special software analyzing tool was employed to determine cutting width (mm) and debris (%). All piezoelectric tips created smooth cuts. Cutting widths in general were wider than the actual insert tip size with a tendency for narrow straight insert tips producing relatively wide osteotomies, whereas narrow angulated inserts produced relatively small osteotomies. None of the samples demonstrated distinct indication of necrosis. Overall, there was only a small amount of debris in all osteotomy gaps. Conventional rotatory saws were faster and created less heat compared to all tested piezoelectric systems. Straight tips proved faster osteotomy speed than angulated tips. Thin insert tips indicated to have a positive correlation to osteotomy time and performed faster than conventional microsaw. The average temperature rise was lower when using conventional systems, but critical exceeding temperatures were only observed in short-time exceptional cases. In general, temperature rise was less when using angulated inserts. All tested tips are appropriate for bone surgery. Only small differences were found among the piezoelectric insert tips. Although conventional rotatory systems in general performed faster osteotomies, special designed and thin piezoelectric insert tips seem to have a positive influence on osteotomy speed. Ultimately, none of the tested devices or inserts combined all best features of speed, heat development, bone structure influence, and safety. Narrow and straight piezoelectric insert tips demonstrated reduced osteotomy times. Nevertheless, a combination of conventional and piezoelectric systems in clinical practice might be the best way to work time-efficient, patient-oriented, and safe. The choice of instrument should be based on clinical experience of the user and should be evaluated individually depending on the case.

Piezoelectric surgery versus mechanical drilling for orbital floor decompression: effect on infraorbital hypoaesthesia

ABSTRACT Purpose: To compare efficacy and safety of mechanical drill and piezoelectric technology in the prevention of infraorbital nerve hypoaesthesia during orbital floor decompression. Methods: Single-centre, non-randomized prospective, interventional case series. We enrolled 24 patients who underwent 3-wall orbital decompression. A total of 13 patients underwent floor decompression using 5-mm diamond dusted Piezoelectric tip (Synthes GmbH, Oberdorf, Germany), whereas 11 patients underwent conventional mechanical decompression of the floor using Stryker Core handpiece with 5-mm diamond dusted tip (Stryker, USA) and a Kerrison’s bone ronguer. All surgeries were performed by a single surgeon (MNN) using standard surgical technique. The infraorbital nerve hypoesthesia was measured pre-operatively, and post-operatively on day 1, at 1 week, 6 weeks, 3 months, and final follow-up by an independent observer. Hypoaesthesia was graded on a simple numerical scale: 0 defined as “normal”, 1 defined as “minimally reduced”, 2 defined as “grossly reduced but perceptible”, and 3 defined as “total loss”. Results: The average follow-up after surgery was 16 months (range 13–48 months). The average score in the mechanical drilling group at day 1, week 6, week 12 and final follow-up was 1.9, 1.2, 0.7, and 0.6, respectively (p < 0.001). For the Piezo group, the average scores were 0.3, 0.2, 0.1, and 0.1, respectively. No procedure related complications were noted, and the average surgical time for floor decompression was comparable (p > 0.5). Conclusions: Piezoelectric technology is effective in orbital floor removal by minimizing infraorbital nerve hypoaesthesia.

Tooth sectioning for coronectomy: how to perform?

The aim of this study was to determine the increase in heat production, preparation time, and cutting surface quality of conventional, high-speed rotating instruments and piezoelectric preparation for coronectomy procedures. One hundred intact extracted molars were sectioned horizontally, sub-totally, 1mm under the cemento-enamel line with five methods: (1) tungsten carbide torpedo (TcT), (2) round (TcR) drills using a conventional speed surgical straight handpiece (< 40,000min-1), (3) tungsten carbide fissure (TcF), (4) diamond torpedo (DT) drills using a surgical high-speed, contra-angle handpiece (~ 120,000min-1), or (5) a saw-like piezoelectric tip (PT). Temperatures, preparation times, and cutting surface irregularities were registered and the differences were analyzed with ANOVA, Tukey's HSD post hoc test (temperature, time) and with chi-square test (irregular surface). Rotating instruments produced a maximal temperature increase of less than 1°C. TcF produced the least heat (ΔT = - 3.92°C to the baseline), while PT produced significantly the highest temperature increases (ΔT = 12.38°C, p < 0.001). Tungsten carbide drills were the fastest for coronectomy (from 55.9 to 64.3s), while DT (169.7s) while PT (146.8s) were significantly slower. TcT and TcR drills produced an irregular root surface more frequently. During coronectomy, rotating instruments produced entirely acceptable heat, while PT produced unacceptable temperatures. Tungsten carbide drills performed coronectomies effectively, but the diamond torpedo and PT seemed clinically questionable. Considering heat, speed, and the cutting surface quality simultaneously, TcF in a surgical high-speed handpiece seems to be the best choice for coronectomy. The correct insert can significantly reduce excessive heat and operation time during coronectomy procedures.

Intracanal temperature changes during bone preparations close to and penetrating the inferior alveolar canal: Drills versus piezosurgery

PurposeThe aim of this in vitro study was to investigate temperature increases in the inferior alveolar canal (IAC), when different bone preparation methods approximate and penetrate the IAC. Materials and methodsIn pig mandible, buccal bone removals were performed until the neurovascular bundle became visible. Temperatures were registered with thermocouple probes and with infrared thermometer. Preparations were performed with diamond drills (DD), tungsten carbide drills (TCD), piezoelectric diamond sphere (PT_D) and saw (PT_S) tips, and a combined preparation method was also performed whereby the superficial three-fourths of the bone was removed with TCD and the deepest one-fourth of the bone with PT_D (TCD + PT_D_7 °C) or PT_S (TCD + PT_S_7 °C), using cooled irrigation (7 °C). ResultsPreparations using room temperature irrigation caused significantly less heat on the bone surface than in the IAC. Piezosurgery in the IAC produced significantly higher temperatures (>13 °C) than the drills (<4 °C). Heat productions of the piezoelectric tips were reduced significantly by applying the combined bone removal methods. The speed of PT_S and TCD + PT_S_7 °C were comparable to the speed of TCD, whereas TCD + PT_D_7 °C was found to be significantly slower. ConclusionThe speed of piezosurgery is comparable to that of the drills; however, it produces the highest, potentially nerve-harming temperatures. To eliminate the heat consequences during piezosurgery in the IAC, the use of cooled irrigation at 7 °C and predrilling is recommended.

Modelling and simulation of static deflection behaviour of non-prismatic multilayer piezoelectric nanocantilevers using non-local effects with simple polynomial solutions

Static deflection analysis of Euler–Bernoulli non-prismatic multilayer piezoelectric nano electromechanical (p-NEM) cantilever beams have been studied in theoretical and simulation aspects for various profiles of p-NEM cantilevers by applying the electrical load. Eringen’s non-local elasticity theory has been implemented to study the transverse piezoelectric deflection and tip displacement of p-NEM cantilevers and solution were obtained using simple polynomials. This method is applied to various profiles like the rectangular and trapezoidal shape of three different thickness (h/2, h and 2h) of piezoelectric layer. The dominance of non-local effects with electric field is also evaluated. The obtained results are compared with experimental results and it is concluded that better deflection is obtained for the trapezoidal profile with h/2 thickness of ZnO piezoelectric layer of suitable nanocantilevers for nanoscale applications. This investigation will be very useful for designing the p-NEM cantilever for biological/ chemical sensing, nanogenerators and energy harvesting applications.

The performance characteristics of a piezoelectric ultrasonic dental scaler

The objective of this work was to investigate the performance characteristics of a piezoelectric ultrasonic dental scaler using scanning laser vibrometry. The vibration characteristics of three standard piezoelectric tips were assessed with scanning laser vibrometry under various conditions: unconstrained, under a stream of flowing water, in a water tank, as well as subjected to loads to simulate clinical conditions. Subsequently, the tips were used to disrupt an in-vitro biofilm model of dental plaque, developed using a non-pathogenic Gram-negative species of Serratia (NCIMB40259).The laser vibrometry data showed that the oscillation pattern of the ultrasonic tip depends primarily on its shape and design, as well as on the generator power. Thin tips and high power settings induce the highest vibrations. Water irrigation of the tip and loads influence the tip performance by diminishing its vibration, while water volume increases it.Serratia biofilm was disrupted by the cavitation bubbles occurring around the scaler tip. The most effective biofilm removal occurred with the thinner tip.Understanding how the ultrasonic tip oscillates when in use and how it removes dental plaque is essential for gaining more knowledge regarding the cleaning mechanisms of the ultrasonic system. Cavitation may be used to remove plaque and calculus without a mechanical contact between the dental tip and the teeth. Better knowledge would enable dental specialists to understand and improve their techniques during routine cleaning of teeth. It will also lead to improving tip design and to the production of more effective instruments for clinical use.

Optimal Design of Piezoelectric Actuator for Precision Positioning Applications

Recent advances in measurement systems require positioning systems with high stiffness, accuracy and speed. Piezoelectric actuators which are featured with mechanical simplicity, quick response, and electromagnetic immunity, are often used in precision positioning. It is known that piezoelectric actuators can achieve high positioning accuracy by the stepping mode but low speed. By contrast, the resonance vibration mode will offer high positioning speed, but sacrifices the high inherent position resolution. For the stepping mode, the displacement of the piezoelectric actuator significantly affects the speed, of which larger displacement induces higher speed. For the resonance vibration mode, an elliptical motion of the piezoelectric actuator tip is generated by horizontal and vertical eigenmodes, and the optimal efficiency can be achieved when the two eigenmodes are operated at the same frequency. For the applications of high positioning accuracy and speed, a piezoelectric actuator should be designed by taking these two operation modes into consideration simultaneously. Based on these requirements, the optimal structural dimensions of a piezoelectric actuator are obtained using a genetic algorithm.

Identification of possible factors influencing temperatures elevation during implant site preparation with piezoelectric technique

Overheating during implant site preparation negatively affects the osseointegration process as well the final outcome of implant rehabilitations. Piezoelectric techniques seem to provide to a gentle implant preparation although few scientific reports have investigated the heat generation and its underlying factors. To investigate, through a proper methodological approach, the main factors influencing temperature rise during piezoelectric implant site preparation. Different piezoelectric tips (IM1s, IM2, P2-3, IM3, Mectron Medical Technology, Carasco, Italy) have been tested. The experimental set-up consisted in a mechanical positioning device equipped with a load cell and a fluoroptic thermometer. The first tip of the sequence (IM1s) generated the highest temperature increasing (ΔT). The diamond tips (IM1s and P2-3) determined higher ΔT values than the smooth tips (IM2 and IM3). Further tests with IM1s suggested that the temperature elevation during the first thirty seconds may be predictive of the maximal temperature as well as of the overall thermal impact. Working load, working movements management and bone features resulted to be the main factors influencing temperature rise during piezoelectric implant site preparation. Irrigant temperature and clogging effect may also synergically contribute to the heat generation.