EFFECT OF NUMBER OF IMPLANTS AND CANTILEVER DESIGN ON STRESS DISTRIBUTION IN THREE-UNIT FIXED PARTIAL DENTURES: A THREE-DIMENSIONAL FINITE ELEMENT ANALYSIS

Park, Ji-Hyun,Kim, Sung-Hun,Han, Jung-Suk,Lee, Jai-Bong,Yang, Jae-Ho The Korean Academy of Prosthodonitics 2008 대한치과보철학회지 Vol.46 No.3

STATEMENT OF PROBLEM: Implant-supported fixed cantilever prostheses are influenced by various biomechanical factors. The information that shows the effect of implant number and position of cantilever on stress in the supporting bone is limited. PURPOSE: The purpose of this study was to investigate the effect of implant number variation and the effect of 2 different cantilever types on stress distribution in the supporting bone, using 3-dimensional finite element analysis. MATERIAL AND METHODS: A 3-D FE model of a mandibular section of bone with a missing second premolar, first molar, and second molar was developed. $4.1{\times}10$ mm screw-type dental implant was selected. 4.0 mm height solid abutments were fixed over all implant fixtures. Type III gold alloy was selected for implant-supported fixed prostheses. For mesial cantilever test, model 1-1 which has three $4.1{\times}10$ mm implants and fixed prosthesis with no pontic, model 1-2 which has two $4.1{\times}10$ mm implants and fixed prosthesis with a central pontic and model 1-3 which has two $4.1{\times}10$ mm implants and fixed prosthesis with mesial cantilever were simulated. And then, 155N oblique force was applied to the buccal cusp of second premolar. For distal cantilever test, model 2-1 which has three $4.1{\times}10$ mm implants and fixed prosthesis with no pontic, model 2-2 which has two $4.1{\times}10$ mm implants and fixed prosthesis with a central pontic and model 2-3 which has two $4.1{\times}10$ mm implants and fixed prosthesis with distal cantilever were simulated. And then, 206N oblique force was applied to the buccal cusp of second premolar. The implant and superstructure were simulated in finite element software(Pro/Engineer wildfire 2.0). The stress values were observed with the maximum von Mises stresses. RESULTS: Among the models without a cantilever, model 1-1 and 2-1 which had three implants, showed lower stress than model 1-2 and 2-2 which had two implants. Although model 2-1 was applied with 206N, it showed lower stress than model 1-2 which was applied with 155N. In models that implant positions of models were same, the amount of applied occlusal load largely influenced the maximum von Mises stress. Model 1-1, 1-2 and 1-3, which were loaded with 155N, showed less stress than corresponding model 2-1, 2-2 and 2- 3 which were loaded with 206N. For the same number of implants, the existence of a cantilever induced the obvious increase of maximum stress. Model 1-3 and 2-3 which had a cantilever, showed much higher stress than the others which had no cantilever. In all models, the von Mises stresses were concentrated at the cortical bone around the cervical region of the implants. Meanwhile, in model 1-1, 1-2 and 1-3, which were loaded on second premolar position, the first premolar participated in stress distribution. First premolars of model 2-1, 2-2 and 2-3 did not participate in stress distribution. CONCLUSION: 1. The more implants supported, the less stress was induced, regardless of applied occlusal loads. 2. The maximum von Mises stress in the bone of the implant-supported three unit fixed dental prosthesis with a mesial cantilever was 1.38 times that with a central pontic. The maximum von Mises stress in the bone of the implant-supported three-unit fixed dental prosthesis with a distal cantilever was 1.59 times that with a central pontic. 3. A distal cantilever induced larger stress in the bone than a mesial cantilever. 4. A adjacent tooth which contacts implant-supported fixed prosthesis participated in the stress distribution.

정밀 마찰측정을 위한 이중 캔틸레버 구조 마찰시험기의 설계에 관한 연구

강원빈(Won-Bin Kang),김현준(Hyun-Joon Kim) 한국트라이볼로지학회 2018 한국윤활학회지(윤활학회지) Vol.34 No.4

A precision tribometer consisting of a cantilever was designed to measure frictional forces in the micro-Newton range. As frictional forces are measured based on the bending of the cantilever, vibration of the cantilever is the most significant factor affecting the quality of the friction measurement. Therefore, improved design of the tribometer with double cantilevers and a connecting plate that united the two cantilevers mechanically was suggested. For the verification of the modified design of the tribometer, numerical analysis and experiments were conducted. Examination using the finite element method revealed that the tribometer with a double cantilever and a connecting plate exhibited faster damping characteristics than the tribometer with a single cantilever. In the experiment, effectiveness of the double cantilever and connecting plate for vibration reduction was also confirmed. Vibration of the tribometer with double cantilever decreased eight times faster than that of the tribometer with a single cantilever. The faster damping of the double cantilever design is attributed to the mechanical interaction at the contacting surfaces between the cantilever and the connecting plate. Tribotesting using the tribometer with a single cantilever resulted in random fluctuation of frictional forces due to the stickslip behavior. However, using the tribometer with a double cantilever and connecting plate for the tribotest gave relatively uniform and steady measurement of frictional forces. Increased stiffness owing to using a double cantilever and mechanical damping of the connecting plate were responsible for the stable friction signal.

골유착성 임플랜트 보철물의 캔틸레버 위치와 길이변화에 따른 삼차원 유한요소법적 응력분석

장복숙,김창회,김영수,Jang, Bok-Sook,Kim, Chang-Whe,Kim, Yung-Soo 대한치과보철학회 1996 대한치과보철학회지 Vol.34 No.3

This study investigated the effects of cantilever length, location and load condition on stress distribution developed in the implants, prostheses and supporting tissues. The osseointegrated prostheses with two 10mm Branemark implants at 2nd premolar and 1st molar sites with cantilever extensions at 1st premolar, 2nd and 3rd molar sites were constructed. Under 100N, 200N of vertical and $45^{\circ}$ oblique loads at the cantilever pontics, stress distribution patterns and displacement were analyzed with three dimensional finite element method. The results were as follows : 1. The stress was concentrated at the joint of the cantilever pontic and implant superstructure, the neck of implant and the ridge crest near the cantilever But there was little load transfer to the lower supporting tissues of implants. 2. The implant near the cantilever was displaced inferiorly while the implant far from the cantilever was displaced superiorly. In horizontal direction the implants were displaced to the direction where the loads were applied, except the apexes of the implants. 3. In case of anterior cantilever, the stress and displacement were higher than the prosthesis connected with natural tooth. 4. The stress developed in the posterior cantilevered type was higher than in the anterior cantilevered type. The greastest stress was concentrated at the ridge crest near the posterior cantilever. 5. The longer the cantilever, the more the stress was developed and was concentrated at the joint of the cantilever pontic and implant superstructure. 6. Under oblique load, the stress was concentrated at the necks of implants and the ridge crests, but decreased at the joint of the cantilever pontic and implant superstructure than under vertical load.

Spiral-shaped SU-8 cantilevers for monitoring mechanical response of cardiomyocytes treated with cardiac drugs

Dai, Y.,Oyunbaatar, N.-E.,Lee, B.-K.,Kim, E.-S.,Lee, D.-W. Elsevier 2018 Sensors and actuators. B Chemical Vol.255 No.3

<P><B>Abstract</B></P> <P>In this paper, a spiral-shaped SU-8 cantilever with biocompatibility was proposed to monitor the changes of cardiac contraction in response to injection of drug in real time. The cantilever comprises a thick quadrate body and a filmy spiral cantilever with micro-grooves and gold patterns on the top of its surface. The longitudinally patterned micro-grooves facilitate the aligned growth of cardiomyocytes in order to increase the contraction force. In addition, the spiral shape increases the cantilever’s effective length and decreases its spring constant, which means its bending displacement can be increased for the same force as compared to that observed in a conventional rectangular cantilever. The bending displacement of the spiral SU-8 cantilever induced by the contraction of cardiomyocytes can be precisely measured at the nanoscale using a homemade laser-based measurement system. The displacement in the spiral SU-8 cantilever without micro-grooves was much greater than that in the case of traditional rectangular SU-8 cantilevers. The displacement produced by the spiral cantilever with grooves is 240% greater than that without grooves. Following preliminary experiments, cardiac drugs including Verapamil, Quinidine, Lidocaine, E-4031, and Bay K 8644 were used to evaluate their side effects on cardiomyocytes. Quantitative analysis of measurements shows that not only Verapamil and Quinidine but also Lidocaine and E-4031 treatment can decrease the cell beating frequency, and both the Verapamil and Lidocaine treatment can decrease the cell contraction force. Furthermore, Bay K 8644 assay results indicate that it can decrease the contraction force and increase the beating frequency of cardiomyocytes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spiral cantilever integrated with micro-grooves is proposed for a real time monitoring of cardiac contractibility. </LI> <LI> Home-made measurement system is developed to precisely measure the contractibility of cardiomyocytes at the nanoscale. </LI> <LI> Five different kind of drugs have been employed for the preliminary study of drug-induced cardiac toxicity. </LI> <LI> Spiral cantilever arrays are expected to be applied as a new method to support for the drawbacks of conventional methods. </LI> </UL> </P>

A Concept of Cantilever’s Optical Dimension for Optimal Application to Cantilever-Based Near-Field Scanning Optical Microscope and Its Measurement

김현태,최수봉,장문규,박두재 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.7

A guide to the selection of the apertured cantilever probe and the numerical aperture of objective lens used in a near-field scanning optical microscope (NSOM) is suggested by defining the Optical dimension of conventional cantilever probe, for achieving highest optical image contrast. An optimized combination between the geometry of the cantilever probe and numerical aperture of the objective lens should be decided for conventional optical head assembly of AFM-based NSOM consisting of cantilever probe and high numerical aperture objective lens, to ensure the light scattered from the specimen being screened by the umbra of cantilever probe, resulting in the light transmitted through the aperture being collected by the objective only. Here, introduction of the optical dimension of cantilever probe, which defines the power of screening the scattered light by the cantilever, conveniently gives us numerical values denoting probe geometry which is critically correlated with the numerical aperture of objective lens with optimized imaging properties. We provide a standard definition of the cantilever’s optical dimension.

Piezoelectric PZT Cantilever Array Integrated with Piezoresistor for High Speed Operation and Calibration of Atomic Force Microscopy

Nam, Hyo-Jin,Kim, Young-Sik,Cho, Seong-Moon,Lee, Caroline-Sunyong,Bu, Jong-Uk,Hong, Jae-Wan The Institute of Electronics and Information Engin 2002 Journal of semiconductor technology and science Vol.2 No.4

Two kinds of PZT cantilevers integrated with a piezoresistor have been newly designed, fabricated, and characterized for high speed AFM. In first cantilever, a piezoresistor is used to sense atomic force acting on tip, while in second cantilever, a piezoresistor is integrated to calibrate hysteresis and creep phenomena of the PZT cantilever. The fabricated PZT cantilevers provide high tip displacement of $0.55\mu\textrm{m}/V$ and high resonant frequency of 73 KHz. A new cantilever structure has been designed to prevent electrical coupling between sensor and PZT actuator and the proposed cantilever shows 5 times lower coupling voltage than that of the previous cantilever. The fabricated PZT cantilever shows a crisp scanned image at 1mm/sec, while the conventional piezo-tube scanner shows blurred image even at $180\mu\textrm{m}/sec$. The non-linear properties of the PZT actuator are also well calibrated using the piezoresistive sensor for calibration.

웨이퍼 본딩을 이용한 탐침형 정보 저장장치용 열-압전 켄틸레버어레이

김영식 ( Young Sik Kim ),장성수 ( Seong Soo Jang ),이선영 ( Sun Young Lee ),진원혁 ( Won Hyeong Jin ),조일주 ( Il Joo Cho ),남효진 ( Hyo Jin Nam ),부종욱 ( Jong Uk Bu ) 정보저장시스템학회 2005 추계학술대회논문집 Vol.2005 No.-

In this research, a wafer-level transfer method of cantilever array on a conventional CMOS circuit has been developed for high density probe-based data storage. The transferred cantilevers were silicon nitride (Si3N4) cantilevers integrated with poly silicon heaters and piezoelectric sensors, called thermo-piezoelectric Si3N4 cantilevers. In this process, we did not use a SOl wafer but a conventional p-type wafer for the fabrication of the thermo-piezoelectric ShN4 cantilever arrays. Furthermore, we have developed a very simple transfer process, requiring only one step of cantilever transfer process for the integration of the CMOS wafer and cantilevers. Using this process, we have fabricated a single thermo-piezoelectric Si3N4 cantilever, and recorded 65nm data bits on a PMMA film and confirmed a charge signal at 5nm of cantilever deflection. And we have successfully applied this method to transfer 34 by 34 thermo-piezoelectric ShN4 cantilever arrays on a CMOS wafer. We obtained reading signals from one of the cantilevers.

Surface-patterned SU-8 cantilever arrays for preliminary screening of cardiac toxicity

Kim, Jong Yun,Choi, Young-Soo,Lee, Bong-Kee,Lee, Dong-Weon Elsevier 2016 Biosensors & bioelectronics Vol.80 No.-

<P><B>Abstract</B></P> <P>Arrays of a μgrooved SU-8 cantilever were utilized to analyze changes in the contraction force and beating frequency of cardiomyocytes <I>in vitro</I>. The longitudinally patterned μgrooves facilitates alignment of cardiomyocytes on top of the SU-8 cantilever, which increases the contraction force of cardiomyocytes by a factor of about 2.5. The bending displacement of the SU-8 cantilever was precisely measured in nanoscale using a laser-based measurement system combined with a motorized <I>xyz</I> stage. The cantilever displacement due to contraction of the cardiomyocytes showed the maximum on day 8 after their cultivation. Following preliminary experiments, Isoproterenol, Verapamil, and Astemizole were used to investigate the effect of drug toxicity on the physiology of cardiomyocytes. The experimental results indicated that 1µM of Isoproterenol treatment increased contraction force and beating frequencies of cardiomyocytes by 30% and 200%, respectively, whereas 500nM of Verapamil treatment decreased contraction force and beating frequencies of cardiomyocytes by 56% and 42%, respectively. A concentration of less than 5nM of the hERG channel suppression drug Astemizole did not change the contraction forces in the displacement but slightly decreased the beating frequencies. However, irregular or abnormal heartbeats were observed at Astemizole concentrations of 5nM and higher. We experimentally conformed that the proposed SU-8 cantilever arrays combined with the laser-based measurement systems has the great potential for a high-throughput drug toxicity screening system in future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper proposes the utilization of micromachined SU-8 cantilever arrays to systematically characterize contraction force of cardiac cells. </LI> <LI> The µgroove patterns facilitates alignment of cardiomyocytes on top of the SU-8 cantilever, which increases their contraction force by a factor of around 2.5. </LI> <LI> The effect of various drugs on the contraction force of the cardiomyocytes is characterized using the SU-8 cantilever. The results reveal that the proposed technique can effectively realize the real-time screening of drug toxicity in cardiomyocytes. </LI> </UL> </P>

Piezoresistive sensor-integrated PDMS cantilever: A new class of device for measuring the drug-induced changes in the mechanical activity of cardiomyocytes

Kim, D.S.,Jeong, Y.J.,Lee, B.K.,Shanmugasundaram, A.,Lee, D.W. Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.240 No.-

Herein, we demonstrate in detail the fabrication and evaluation procedure of a piezoresistive sensor-integrated polydimethylsiloxane (PDMS) cantilever for measuring the drug-induced changes in the contraction force of cardiomyocytes. The proposed device consists of a glass body with metal patterns, a PDMS cantilever with microgrooves (μgrooves), and integrated piezoresistive sensor. Reliability of the piezoresistive sensor and connection wires was greatly improved by using a glass substrate with metal patterns. The longitudinally patterned μgrooves formed on the PDMS cantilever was optimized to maximize cantilever deformation. The mechanical deformation of the cantilever caused by the contraction force of cardiomyocytes is directly observed by using the integrated piezoresistive sensor, whereas the existing methods rely on the optical methods to measure the cantilever displacement. The contraction force is maximized between day eight and nine after seeding the cardiomyocytes onto the PDMS cantilever. After preliminary experiments, the strain sensor integrated μpatterned PDMS cantilever was subjected to measure the change in the contraction force of cardiomyocytes under different concentrations of cardiac drugs. The experimental results showed that the strain sensor integrated PDMS cantilever can effectively verify the changes in the mechanical output of the cardiomyocytes under the drug influence.

Micro Power Generation of a PMN-PZT Triple-morph Cantilever for Electric Harvesting Devices

김인성,Hyeonkyu Joo,정순종,Minsoo Kim,Jaesung Song 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1

A piezoelectric cantilever was manufactured using a PMN-PZT thick film for an electric harvesting device. In order to find better properties, we manufactured the piezoelectric cantilever in two forms (bi-morph and triple-morph); then, the bi-morph cantilever and the triple-morph cantilever were compared as to electric micro power. The generation characteristics were investigated at various frequencies, load resistances, and masses. The output power of the bi-morph piezoelectric cantilever showed a maximum value at 0.25 g mass at 197 Hz, and the triple-morph piezoelectric cantilever showed a maximum at 0.25 g mass at 154 Hz. The piezoelectric cantilever output voltage increased with the increasing load resistance, and the output power quality was investigated by changing the load resistance, the mass, and the frequency. The bi-morph piezoelectric cantilever‘s output power at 33 k , 0.25 g, and 197 Hz was 0.23 mW at 2.75 Vrms, and the average micro power from the triple-morph piezoelectric cantilever was 0.432 mW at 6.57 Vrms and 154 Hz.