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This study uses fluid–structure interaction (FSI) simulation to investigate the relationship between the dentinal fluid flow in the dental pulp of a tooth and the elastic modulus of masticated food particles and to investigate the effects of chewing rate on fluid flow in the dental pulp. Three-dimensional simulation models of a premolar tooth (enamel, dentine, pulp, periodontal ligament, cortical bone, and cancellous bone) and food particle were created. Food particles with elastic modulus of 2,000 and 10,000 MPa were used, respectively. The external displacement loading $$(5\,\upmu \hbox {m})$$ was gradually directed to the food particle surface for 1 and 0.1 s, respectively, to simulate the chewing of food particles. The displacement and stress on tooth structure and fluid flow in the dental pulp were selected as evaluation indices. The results show that masticating food with a high elastic modulus results in high stress and deformation in the tooth structure, causing faster dentinal fluid flow in the pulp in comparison with that obtained with soft food. In addition, fast chewing of hard food particles can induce faster fluid flow in the pulp, which may result in dental pain. FSI analysis is shown to be a useful tool for investigating dental biomechanics during food mastication. FSI simulation can be used to predict intrapulpal fluid flow in dental pulp; this information may provide the clinician with important concept in dental biomechanics during food mastication.

The invasion of the pheretimoid earthworms in North America, especially the genera Amynthas and Metaphire , has raised increasing concerns among ecologists and land managers, in turn increasing the need for proper identification. However, the commonly used keys to this group are more than 30 years old with outdated taxonomic information and are based primarily on internal morphology. The requirement of significant amount of taxonomic expertise and dissection, even from the first entry of the key, has prevented broader use of these keys. As a result, many publications in the United States have used Amynthas spp. to represent the group without identifying the species. We present here a new key and diagnoses for the 16 pheretimoid earthworm species recorded in North America north of Mexico, including four genera: Amynthas (10), Metaphire (4), Pithemera (1), and Polypheretima (1). The descriptions were based on published records with modifications following inspection of specimens archived at the National Museum of Natural History, Smithsonian Institution, Washington, D.C. Photos of external and internal characters, including male pores, spermathecal pores, genital markings, spermathecae, prostate glands, and intestinal caeca, are presented to help identification. A summary of current knowledge about the ecology and historical context is provided for each species. We also highlight the previously overlooked and potentially common and widespread co-occurrence of three species— A. agrestis , A. tokioensis , and M. hilgendorfi —and point out that many recent claims of invasion of A. agrestis need to be re-evaluated for potential misidentification.

Recent developments in nanotechnology have created considerable potential toward diagnosis and cancer therapy. In contrast, the use of nanotechnology in tissue repair or regeneration remains largely unexplored. We hypothesized that intramyocardial injection of insulin-like growth factor (IGF)-1-complexed poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (PLGA-IGF-1 NPs) increases IGF-1 retention, induces Akt phosphorylation, and provides early cardioprotection after acute myocardial infarction (MI). We synthesized 3 different sizes of PLGA particles (60 nm, 200 nm, and 1 μm) which were complexed with IGF-1 using electrostatic force to preserve the biological function of IGF-1. Afterward, we injected PLGA-IGF-1 NPs in the heart after MI directly. Compared with the other two larger particles, the 60 nm-sized PLGA-IGF-1 NPs carried more IGF-1 and induced more Akt phosphorylation in cultured cardiomyocytes. PLGA-IGF-1 NPs also prolonged Akt activation in cardiomyocytes up to 24h and prevented cardiomyocyte apoptosis induced by doxorubicin in a dose-dependent manner. In vivo, PLGA-IGF-1 NP treatment significantly retained more IGF-1 in the myocardium than the IGF-1 alone treatment at 2, 6, 8, and 24 h. Akt phosphorylation was detected in cardiomyocytes 24h post-MI only in hearts receiving PLGA-IGF-1 NP treatment, but not in hearts receiving injection of PBS, IGF-1 or PLGA NPs. Importantly, a single intramyocardial injection of PLGA-IGF-1 NPs was sufficient to prevent cardiomyocyte apoptosis (P0.001), reduce infarct size (P0.05), and improve left ventricle ejection fraction (P0.01) 21 days after experimental MI in mice. Our results not only demonstrate the potential of nanoparticle-based technology as a new approach to treating MI, but also have significant implications for translation of this technology into clinical therapy for ischemic cardiovascular diseases.

Objectives This study uses a fluid–structure interaction (FSI) simulation to evaluate the fluid flow in a dental intrapulpal chamber induced by the deformation of the tooth structure during loading in various directions. Methods The FSI is used for the biomechanics simulation of dental intrapulpal responses with the force loading gradually increasing from 0 to 100 N at 0°, 30°, 45°, 60°, and 90° on the tooth surface in 1 s, respectively. The effect of stress or deformation on tooth and fluid flow changes in the pulp chamber are evaluated. Results A horizontal loading force on a tooth may induce tooth structure deformation, which increases fluid flow velocity in the coronal pulp. Thus, horizontal loading on a tooth may easily induce tooth pain. Conclusion This study suggests that experiments to investigate the relationship between loading in various directions and dental pain should avoid measuring the bulk pulpal fluid flow from radicular pulp, but rather should measure the dentinal fluid flow in the dentinal tubules or coronal pulp. The FSI analysis used here could provide a powerful tool for investigating problems with coupled solid and fluid structures in dental biomechanics.

Bile duct injury (BDI) is the most serious iatrogenic complication during laparoscopic cholecystectomy (LC) and occurs easily in inexperienced surgeons since the position of common bile duct (CBD) and its related ductal junctions are hard to precisely identify in the hepatic anatomy during surgery. BDI can be devastating, leading to chronic morbidity, high mortality, and prolonged hospitalization. In addition, it is the most frequent injury resulting in litigation and the most likely injury associated with a successful medical malpractice claim against surgeons. This study introduces a novel method for conveniently and rapidly indicating the anatomical location of CBD during LC by the direct fiber-optic illumination of 532-nm diode-pumped solid state laser through a microstructured plastic optical fiber to avoid the wrong identification of CBD and the injury from mistakenly cutting the CBD that can lead to permanent and even life threatening consequences. Six porcine were used for preliminary intra-CBD illumination experiments via laparotomy and direct duodenal incision to insert the invented CBD illumination laser catheter with nonharmful but satisfactory visual optical density.

This paper presents the development and normalization of a novel sensor system built with low-cost industrial-grade multilayer ceramic capacitors (MLCC). MLCCs play both the roles of force sensing elements and force sustaining elements. With adopting this low-cost industrial component of MLCC (less than 1 cent USD for a sensing component), the time and the cost for producing a high performance force sensor system can be achieved. Practically, industrial-grade MLCCs are produced for capacitor applications but not for a sensing element for force measurement. However, the sensitivity for each independent MLCC presents a large variation for force sensing (coefficient of variation around 0.6). This study successfully overcome this drawback, a simple poling process is demonstrated to both increase the sensitivity and to reduce the variation coefficient of MLCC force sensors. Results indicate that the variation for the MLCCs after re-poling treatment is reduced to 0.02. The effects on the poling voltage and poling time are experimentally investigated. Results show that the MLCC treated with a high poling field can increase sensitivity and also reduce the variation for force sensing. This re-poling treatment is essential for developing a simple and low cost MLCC-based force sensor system that can be used in a wide variety of applications.

A new germacrane-type sesquiterpenoid, menelloide E (1), and a new cembrane-type diterpenoid, lobocrassin F (2), were isolated from the octocorals Menella sp. and Lobophytum crassum, respectively. The structures of terpenoids 1 and 2 were determined by spectroscopic and chemical methods and compound 2 was found to display a significant inhibitory effect on the release of elastase by human neutrophils.

Introduction The success rate of miniplates is superior to that of other temporary anchorage devices; nevertheless, the biomechanical behavior of miniplates during orthodontic use is not totally understood. The aim of this study was to investigate bone stress by finite element analysis when miniplates are used for orthodontic anchorage. Methods A 3-dimensional model consisting of a bone block integrated with a miniplate and fixation screw system was constructed to simulate various types of miniplates, screw numbers, screw lengths, cortex thicknesses, and force magnitudes and directions. Results The peak von Mises cortex stress values were highest with the I-type plates followed by the L-type, Y-type, and T-type plates. Bone stress decreased as the screw numbers increased but was not related to screw length. Bone stress increased as the cortex thickness decreased. Bone stress was linearly proportional to the force magnitude, and the highest values were produced when the force was in the forward direction. Conclusions When a T- or Y-type plate is used, or when the force direction is in the tensile mode, bone stress decreases. Bone stress also decreases as the screw numbers increase and as the cortex thickness increases. Furthermore, it decreases as the force magnitude becomes less.

The objective of this study was to examine the effects of cavity configuration on the polymerization shrinkage and stress of light-cured composite restorations by combining local strain measurement and a finite element analysis (FEA). Dental mesio-occluso-distal cavities of various widths and depths (each for 2 vs. 4 mm), representing different configuration factors, were prepared on extracted molars. The displacements of the bonded tooth cusps and cavity floors, caused by polymerization shrinkage of composite restorations, were assessed utilizing a digital-image-correlation (DIC) technique. The cervical marginal microleakage was investigated by examining the resin replicas of these restorations under SEM. The local material properties of the polymerized composite along the curing depth were defined by the nanoindentation test and applied in the subsequent FEA. In the FEA, four models were generated to correspond with the experimental restorations. In the DIC measurement results, the 4 ( w ) × 4 ( D ) mm cavity presented the greatest values of inward displacements at the cusp and floor. The cavity depth, rather than the cavity width, was found to significantly correlate to the floor deformation, the location of shrinkage centers, and also the cervical microleakage ratio. The FEA simulation results showed that the 2 ( w ) × 4 ( D ) mm cavity presented the maximal von Mises and principal stress located respectively on the cervical margins and cavity floor. Additional safety factor analysis showed a high risk of bond failure over the cavity floor in the 4-mm deep cavity. With the experimental validation, the simulation revealed that the cavity depth was significant to the formation of contraction stress and the incidence of interfacial debonding.

This study presents a novel flexible force sensor array for measuring the distribution of the force distribution over the first molar. The developed force sensor array is composed of a flexible polyimide electrode and barium-titanate-based multilayer ceramic capacitors (MLCCs). The piezoelectric and material properties of industrial-grade MLCCs are ideal for measuring large-force loadings. The sensors are cheap and easy to integrate with automated manufacturing processes. Prior to experimental measurements, the force responses for the MLCC sensor cells were systematically measured and evaluated, confirming their high fracture strength and good sensing properties. Finite element (FE) simulations were used to calculate the force distribution over the tooth crown from the measurement results of the 3×3 force sensor array. Results indicate that the sensor has great sensitivity and linearity under a high-speed cycle loading of 500 N/s conducted to simulate normal chewing. The total force measured using the developed sensor array within the artificial tooth had an error of less than 5%. In addition, the force distributions over the molar crown obtained using a numerical method of FE analysis agree well with those obtained from experiments. The developed flexible force sensor array thus has potential for in-situ bite force measurements that are low-cost and reliable.

Cast posts require sufficient length for prosthesis retention and root strength. For prefabricated metal and fiber posts, the effects of different post lengths on the strength and internal stress of the surrounding root need evaluation.The purpose of this study was to examine, using both experimental and finite element (FE) approaches, the influence of post material and length on the mechanical response of endodontically treated teeth.Sixty extracted incisors were endodontically treated and then restored with 1 of 3 prefabricated posts: stainless steel (SS), carbon fiber (CF), and glass fiber (GF), with intraradicular lengths of either 5 or 10 mm (n=10). After composite resin core and crown restorations, these teeth were thermal cycled and then loaded to fracture in an oblique direction. Statistical analysis was performed for the effects of post material and length on failure loads using 2-way ANOVA (α=.05). In addition, corresponding FE models of an incisor restored with a post were developed to examine mechanical responses. The simulated tooth was loaded with a 100-N oblique force to analyze the stress in the root dentin.The SS/5 mm and all fiber post groups presented no statistical differences, with mean (SD) fracture loads of 1247 to 1339 (53 to 121) N. The SS/10 mm group exhibited a lower fracture load, 973 (115) N, and a higher incidence of unfavorable root fracture (P.05). The FE analysis showed high stress around the apical end of the long SS post, while stress was concentrated around the crown margins in the fiber post groups.Both long and short fiber posts provided root fracture resistance comparable to that of SS posts. For metal posts, extending the post length does not effectively prevent root fracture in restored teeth.

This paper presents a novel yet high performance diascopic illumination configuration for simultaneously detecting cells of different sizes and different fluorescence labeling in a microfluidic chip. An objective-type dark-field condenser equipped with a low-cost tungsten bulb light source with continuous wavelengths (400 to 900 nm) and an UV-Vis-NIR spectrometer is used for detecting the multispectral signals from various particles and cells. With this approach, continuous cell counting and spectra analyzing are realized in a single channel without using any spatial filter and delicate optical detectors. Results show that the developed system is capable of identifying different labeled particle and cell samples by extracting the information side-scatter, absorption, and fluorescence from the information-rich spectra. This proposed system provides an efficient multi-color detection for identification and classification on a micro-flow cytometer chip.

In this paper we investigate the near-field optical behavior of plasmon coupling in gold nanoparticle pairs. In particular, by performing series measurements through a fiber-collection mode near-field scanning optical microscope (NSOM), we directly observed the localized electromagnetic (EM) field distribution between two nanospheres is sensitively depended on the incident polarization and interparticle distance. The qualitative near-field observation and quantitative analysis facilitate more understanding of localized hot spots in surface-enhanced Raman scattering (SERS), and nano-applications in selectively controlling the spatial distribution of localized surface plasmon (SP) modes on a fabricated nanostructure by adjusting the polarization direction.

Surface-enhanced Raman scattering (SERS) on gold nanohole and nanodisk arrays with precisely controlled size, spacing and shapes of rod, and circle fabricated via focused ion beam was investigated by 632- and 785-nm lasers. Results demonstrate that nanodisks and nanoholes exhibit strong SERS signals at 632-nm excitation, but only rod nanoholes present SERS signals at 785-nm excitation. The normal incidence transmission spectrum of nanoholes shows the extension of near-infrared wavelength, but not for nanodisks. The broadband wavelength of plasmon resonance and space confined by rod nanoholes suggest promise for being a functional component in biosensing, Raman spectroscopy, and photonic devices.

The near-field distribution of plasmonic coupling effect in gold nanoparticle pairs was directly investigated by a nearfield scanning optical microscope (NSOM) in the fiber-collection mode. NOSM images show that the localized plasmonic coupling and the electromagnetic field distribution of nanoparticle pairs are systematically influenced by the interparticle space and axial direction of incident polarization. This observation can facilitate the understanding of localized hot spots in surface-enhanced Raman spectroscopy in the near field and can be used as a guideline for fabricating specific nanostructures in controlling the spatial distribution of surface plasmon (SP) modes for ultrasensitive sensors or photonic devices.

Dipole and quadrupole surface plasmon polariton (LSPP) resonances of gold nanoparticle array were directly investigated by a near-field scanning optical microscope (NSOM) in the fiber-collection mode. Separated gold nanoparticles on the quartz substrate were fabricated by nanosphere lithography. Results demonstrate that controlling the incident polarization and angle of oblique incidence enables to excite dipolar and quadrupolar LSPP at 633- and 488-nm excitations. This observation facilitates the understanding of LSPP and interactions with nanostructures in the near field that can be used as a guideline for fabricating nanostructures in controlling spatial distributions of LSPP for ultra sensitive bio-/chemo-detectors or plasmonic metamaterials.

Quantitative ultrasound (QUS) measurements have been proposed for quantitative evaluation of bone tissue noninvasively. It also demonstrated to have the potential to evaluate the properties of tendon. Stress strain properties of tendon are important information for many clinical applications, such as monitoring the recovering progression of surgery or overloading of tendon. Therefore, in this study we designed a system combining QUS technique and stress-strain measurement for tendon by studying the correlation between the stress strain properties and QUS parameters. The proposed system consists of three major devices to measure 1) stress, 2) QUS parameters, and 3) cross-sectional areas of tendons. A laser displacement sensor mounted on a rotary was designed to measure the cross-sectional area. Achilles tendons used in the experiments were obtained from 10 porcine specimens. The results show that the cross-sectional area of tendon decreases with increased loading, which has high correlation (R2 = 0.73) with the thickness evaluated by ultrasonic technique. In addition, the obtained QUS parameters show that both ultrasonic attenuation and speed of sound (SOS) decrease along with increased loading. In conclusion, thickness evaluated by ultrasonic technique is useful for calculating QUS parameters, and for analyzing non-uniform soft tissues. This study indicated that the attenuation and SOS are potential candidate parameters for evaluating the properties of tendon noninvasively.

This paper presents an advanced diascopic illumination technique for simultaneously multi-wavelength fluorescence excitation and detection without any filter sets. High-throughput capillary electrophoresis detection can be realized with this simple and novel approach. The developed system is composed of a home-built dark-field condenser for fluorescence excitation and an ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer for emitted signal detection. Experimental results show that the proposed system can effectively increase the fluorescent signal. In CE experiment, a fluorescent sample, Rhodamine B, can be successfully detected using this proposed system. Furthermore, a mixed bio-sample composed of three single-strand DNAs labeled with Cy3, FITC, and Alexa647 are successfully separated and detected in a single test run. Results indicate the developed system is capable of achieving full wavelength-resolved fluorescence detection in a single microfluidic channel. The measured detection limit for the developed system is up to 5×10−8} M (S/N = 3) while detecting a standard fluorescein, which is suitable for general bio-analytical applications.

Objectives To analyze the influence of cavity geometry and lining materials in MOD composite restorations by characterizing the polymerization shrinkage and cusp deflection. Methods Eighty intact molars with similar sizes were collected and randomly divided into eight groups. MOD cavities with various widths and depths were prepared on these teeth: Group I, 2 ( W ) × 2 ( D ) mm; Group II, 4 ( W ) × 2 ( D ) mm; Groups III, IIIf, IIIg, 2 ( W ) × 4 ( D ) mm; and Groups IV, IVf, IVg, 4 ( W ) × 4 ( D ) mm. In Groups IIIf and IVf, flowable composite liner was placed prior to composite restoration, while glass-ionomer liner was used in Groups IIIg and IVg. Deformations of restorations resulted from composite shrinkage were recorded for 30 min following light irradiation using a digital-image-correlation (DIC) method to subpixel level. The displacements at the boundaries of the restorations were analyzed using one-way ANOVA and the post hoc test at a 5% significance level. The correlation between the geometric factors and the displacements was also analyzed. Results The inward displacements on free surfaces were greater than those on the bonded surfaces. Groups with flowable composite linings showed greater amount of displacements on free and bonded surfaces compared to the unlined and glass ionomer lining groups. The correlation analysis showed that the free surface shrinkage was related with the cavity width and C-factor, while cusp deflections were correlated with the cavity depth and the cusp compliance. Significance The DIC technique measures composite shrinkage on different boundaries of restorations to facilitate the investigation of polymerization kinetics. Using flowable composite lining and increased cusp depth may aggravate the cusp flexure.

Surface plasmon coupling effects of isolated and collective Au nanoparticle arrays are investigated through the optical transmission spectroscopy and near-field scanning optical microscope (NSOM). Nanoparticle arrays with different collective degrees are fabricated by the nanosphere lithography and self-assembling technique. The absorption wavelength of collective nanoparticle array at surface plasmon resonance orients to longer wavelengths due to the particularly strong localized electromagnetic field exists in the gap of nanoparticle pairs. Besides, results manifest that localized surface plasmon coupling not only depends on the inter-particle distance but also relates to the photon-plasmon resonance.

Interference patterns between photon excitation and plasmon mediated re-radiation are revealed on a metal nanoparticle basis. The plasmon-photon interaction is directly observed in the vicinity of silver nanoparticles through a near-field scanning optical microscope (NSOM). Isolated silver nanoparticles with different sizes on the pure quartz substrate are simultaneously fabricated through a high temperature annealing technique. Our results manifest that the correlation of phase-response and size-dependent optical enhancement can be further applied to control the spatial distribution of localized surface plasmon modes by means of framed nanostructures.

Subjects with Diabetes Mellitus (DM) are the major parts in transtibial amputees. The purpose of this study is to investigate the difference on the material properties of soft tissues and biomechanical performance between the DM and non-DM subjects. There are two volunteers with transtibial amputation involved in this study. One is suffered from DM, the other is not. This study were executed within two major phased. Firstly, the stiffness of soft tissue at five regions of stump was received from the self-made force-displacement instrument. Then, the finite element models of the two subjects were established to simulate the biomechanics of transtibial prosthesis. From the results, the stiffness of non-DM subject is averagely 1.6 times higher than the DM subject. In the finite element analysis, the DM subject were presented the higher magnitudes at the maximum sliding distance, the interface stresses, Von Mises stress and Von Mises strain. It means the soft tissue of DM subjects with lower stiffness had higher chance to be broken. When manufacturing the prosthesis for DM subjects, the prosthesists should notice this invisible problem..

The earthworms of the Metaphire formosae species group distributed in Taiwan are members of the Pheretima complex within the Megascolecidae. In this study, the systematics and phylogeography of this species group were investigated using DNA sequences of mitochondrial cytochrome c oxidase subunit I (COI), 16S ribosomal (r)RNA, and NADH dehydrogenase subunit 1 (ND1). The results indicated that the 13 taxa of the M. formosae species group form a clade, including a cryptic species discovered in this study. In addition, Metaphire hengchunensis (James, S.W., Shih, H.-T., Chang, H.-W., 2005. Seven new species of Amynthas (Clitellata: Megascolecidae) and new earthworm records from Taiwan. J. Nat. Hist. 39, 1007-1028) should be regarded as a subspecies of Metaphire paiwanna Tsai, C.-F., Shen, H.-P., Tsai, S.-C., 2000a. Native and exotic species of terrestrial earthworm (Oligochaeta) in Taiwan with reference to Northeast Asia. Zool. Stud. 39, 285-294, Tsai, C.-F., Tsai, S.-C., Liaw, G.-J., 2000b. Two new species of pontandric pheretimoid earthworms belonging to the genus Metaphire (Megascolecidae: Oligochaeta) from Taiwan. J. Nat. Hist. 34, 1731-1741, and Metaphire bununa glareosa Tsai et al. 2000 should be elevated to specific status. Phylogeographical inferences showed that allopatric speciation occurred in this species group during the rapid uplift of the main island of Taiwan between 5.0 and 2.5 million years ago. Our analysis exposes non-monophyly within each of the genera Amynthas and Metaphire, and more generally within the Pheretima complex. Further revisions of this speciose complex are urgently needed.

Objectives To evaluate the effects of fluoridated bleaching agents and post-bleaching fluoridation treatment on the whitening efficiency and microhardness of bovine enamel. Methods Twenty five freshly extracted bovine incisors were cut into halves, embedded and then divided into the following five groups: Group 1, untreated controls; Group 2, treatment with 10% carbamide peroxide (CP) bleaching agent; Group 3, treatment with 10% CP followed by a 0.9% sodium fluoride gel application, Group 4, treatment with 10% CP containing 0.11% fluoride; Group 5, treatment with an experimental bleaching agent consisting of 10% CP and 0.37% fluoride. Groups 2–5 were treated 8 h per day for 14 days then immersed in saliva for 2 weeks. Enamel morphology changes were evaluated under SEM on Day 14. Changes in enamel color and microhardness were evaluated on Days 7 and 14, and compared with the baseline data. Additionally, microhardness was determined on post-bleaching Days 21 and 28. Results After 2 weeks, an erosion pattern was noted on the specimens in Groups 2 and 3. Groups 4 and 5 showed a milder demineralized pattern. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 3 showed significantly decreased enamel microhardness compared to their baseline data. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. Conclusions The fluoridated bleaching agents produced less demineralization of surface morphology and microhardness. The addition of fluoride did not impede the whitening effect.

Interferences between photon excitation and plasmon mediated re-radiation are revealed on a nanoparticle basis through NSOM. Results manifest the correlation of phase-response and size-dependent optical enhancement to control surface plasmon modes by means of nanostructures.

Resin-based composites have become widely used in dental restorative materials. Although they exhibit advantages as tooth-color appearance and enough strength, the polymerization shrinkage is criticized as their inherent defect. Clinically, shrinkage leads to post-restorative consequences such as distortion of restorations, the bonded tooth deflection and even microfracture in a weakened tooth [1, 2]. A method to identify the shrinkage direction and amount is necessary in evaluating these materials.

summary Three-dimensional, anisotropic finite element models were executed to investigate the biomechanical effects of in-line and offset placements of implants on implant-supported partial prostheses. Three implant placements of finite element models were created: in-line, buccal offset and lingual offset placements. The mesh models of a cadaver mandibular segment and a three-united crown containing the 2nd premolar, the 1st molar and the 2nd molar were constructed by computer tomography images. The material properties of mandible were applied as transversely isotropic and linearly elastic. Two loading modes (100N), vertical and oblique, were evaluated in all models. Insignificant difference was observed in implant stresses between the in-line and offset placements under the vertical loading mode. Under the oblique loading, however, the offset placement decreased the implant stress by a maximum of 17%. The maximum stress at cortical bone and trabecular bone around each implant did not show conspicuous difference between the in-line and offset placements. This study demonstrated the mechanisms of how stresses were distributed between the in-line and offset placements. Even though the offset placements showed the benefit of decreasing implant stresses, justified from the bone stress the offset placements provided no advantage for the stress decreasing over the in-line placement.

The purpose of this study was to provide more information about the morphological characteristics of the craniofacial complex in mandibular prognathism. Forty young adult males having mandibular prognathism were compared with 40 having normal occlusion. This was conducted to carry out geometric morphometric assessments to localize alterations, using Procrustes analysis and thin-plate spline analysis, in addition to conventional cephalometric techniques. Procrustes analysis indicated that the mean craniofacial, midfacial and mandibular morphology was significantly different in prognathic subjects compared with normal controls. This finding was corroborated by the multivariate Hotelling T(2)-test of cephalometric variables. Mandibular prognathism demonstrated a shorter and slightly retropositioned maxilla, a greater total length and anterior positioning of the mandible. Thin-plate spline analysis revealed a developmental diminution of the palatomaxillary region anteroposteriorly and a developmental elongation of the mandible anteroposteriorly, leading to the appearance of a prognathic mandibular profile. In conclusion, thin-plate spline analysis seems to provide a valuable supplement for conventional cephalometric analysis because the complex patterns of craniofacial shape change are visualized suggestive by means of grid deformations.

This work proposes a two-stage immune algorithm that embeds the compromise programming to perform multi-objective optimal capacitor placement. A new problem formulation model that involves fuzzy sets to reflect the imprecise nature of objectives and incorporates multiple planning requirements is presented. The proposed approach finds a set of noninferior (Pareto) solutions rather than any single aggregated optimal solution. Additionally, this developed approach eliminates the need for any userdefined weight factor to aggregate all objectives. Comparative studies are conducted on an actual system with encouraging results, demonstrating the effectiveness of the proposed presented approach.

Three new species of octothecate Metaphire pheretimoid earthworms are described from Taiwan. They have close phylogenetic relationships with five described species, Metaphire paiwanna, Metaphire bununa, Metaphire riukiuensis, Metaphire taiwanensis, and Amynthas formosae. These eight species are all octothecate. They have similar body size, colour, prostate glands and caeca, and the seven species belonging to the genus Metaphire have C‐shaped male pores. Excluding M. riukiuensis, which has been found only in the Ryukyu Islands, the other seven species are endemic species in Taiwan. Each of them has a distinct geographical distribution. Accordingly, we inferred that the ancestor of these eight species, including M. riukiuensis, came to Taiwan from the continent of East Asia during the Pleistocene. A few of their descendants went northward to the Ryukyu Islands and were isolated. The others remained in Taiwan, dispersed, and were isolated by geographical barriers such as mountains and rivers. Subsequent allo...

summary The aim of this study was to investigate the treatment effects on the maxillofacial complex by maxillary protraction combined with chin cup therapy among growing children. An effective geometric morphometric assessment of cephalometric radiographs, using Procrustes analysis and thin-plate spline analysis, was applied to evaluate shape change in the craniofacial and midfacial configurations of a treated sample of 20 children with skeletal Class III malocclusion. This was compared with matched untreated skeletal Class III controls. Marked treatment induced change involved the maxilla and the mandible. Major deformation consisted of forward advancement of the maxillary complex with negligible rotation of the palatal plane and a forward direction of growth of the mandibular condyle associated with a restriction in sagittal advancement of the chin. Considerable dentoalveolar components contributed to the correction of anterior crossbite. Further detailed study of skeletofacial remodelling in response to maxillary protraction in other skeletal components, including the cranial base and the mandibular complex that contribute to Class III skeletal discrepancies, is warranted.

Three-dimensional finite element (FE) models of splinted prosthetic crowns were studied and stress analyses were evaluated with different types of implant support, including standard, wide or two implant(s) for partial, posterior edentulous restorations.The FE models were constructed based on a cadaver mandible containing the 2nd premolar and the 1st molar. The crowns of these two teeth were modeled as connected and disconnected to mimic the splinted and non-splinted designs, respectively. One standard implant was placed at the premolar region, while three types of implant support, one at a time (the standard implant, wide implant and two implants), were used to support the molar crown. A 100 N oblique load was applied to the buccal cusp on each crown. The FE simulation was validated experimentally via strain gauge measurement.The experimental data were well correlated with the FE predictions (r(2)=0.97). When compared with the standard implant used in the molar area, the wide implant and two implants reduced the peak stress in crestal bone by 29-37% for both splinted and non-splinted cases. Inserting the standard implant into both the premolar and molar area, the bone stresses were identical for splinted and non-splinted designs. However, splinting the adjacent crowns has shown to decrease the bone stresses at the premolar region by 25%, while the wide implant or two implants were placed at the molar region.The biomechanical advantages of using the wide implant or two implants are almost identical. The benefit of load sharing by the splinted crowns is notable only when the implants on the premolar and molar regions have different supporting ability.

There is insufficient evidence in conventional cephalometric analysis of the actual sites of putative maxillofacial change in Class II and Class III malocclusions. The purpose of this study was to provide more information about the morphological characteristics of the midfacial complex and mandible in children with Class II or III malocclusions. Seventy children with Class II, division 1 malocclusion and 70 children with Class III malocclusion were compared with 70 children with normal occlusion. This study was conducted to carry out geometric morphometric assessments to localize alterations using Procrustes analysis and thin-plate spline analysis. Procrustes analysis indicated the midfacial and mandibular morphologies differed between normal occlusion subjects and subjects with Class II or Class III malocclusion (P

According to its design concept, a resin-bonded prosthesis, compared with the conventional fixed partial denture, is a weak and unstable structure. Therefore, a resin-bonded prosthesis induces a higher failure rate, especially in the posterior region. Recently, adhesion agents have been profoundly improved. However, the design guidelines of posterior resin-bonded prostheses (RBP) have seldom been evaluated from a biomechanical perspective. The objective of this study was to investigate the biomechanical effects of the retainer thickness on posterior RBP using the finite element method. A solid model of a posterior mandibular resin-bonded prosthesis, which employed the second molar and second premolar as the abutment teeth, was constructed and meshed with various retainer thickness (ranging from 0.2 to 1.0 mm). Horizontal and vertical loadings of 200 N were applied respectively at the central fossa of the pontic to examine the stress level at the interface between the retainer and abutment teeth. All exterior nodes in the root, below the cementoenamel junction were fixed as the boundary condition. The results showed that horizontal loading would induce higher interfacial stresses than the vertical loading which indicated that the horizontal component of the occlusal force plays a more important role in evaluating the debonding phenomenon. Further, the peak interfacial stresses increased as the retainer thickness decreased and, based on the fitted relation between retainer thickness and interfacial stresses, a 0.4 mm retainer thickness was suggested as the minimum required to prevent severe interfacial stresses increasing.

This in vitro study aimed to investigate the influence of flowable composite lining with different thicknesses on the marginal quality and internal porosity of Class II composite restorations. Thirty-two intact molars, each prepared with two box-only Class II cavities, were randomly divided into four groups: Group 1, P60 filling alone; Group 2, ultrathin flowable composite lining/co-cured with overlaying composite; Group 3, thin lining/pre-cured and Group 4, thick lining/pre-cured. The teeth were then thermocycled for 1500 cycles (between 5 degrees C and 60 degrees C) and dye immersed for 24 hours. Exterior surface replicas of these restorations were fabricated before and after thermocycling and examined by SEM to evaluate percentages of the five marginal patterns. Data was statistically evaluated using one-way ANOVA test. The teeth were subsequently sectioned longitudinally. The interface microleakage of cervical margin was measured as to the extent of dye penetration. Internal voids were separately recorded in the cervical interface and the cervical and occlusal halves of the restorations. Mann-Whitney test was applied to analyze the interface microleakage and internal voids. Results revealed that replicas of Group 4 presented the highest percentage of marginal openings both before and after thermocycling in SEM examination. Group 2 exhibited superior marginal quality in interface microleakage evaluation compared to the other groups, while Group 4 exhibited the worst. The pre-cured groups (Group 3 and 4) showed significant reduction in interface and cervical voids. Despite the reduction in interface voids, a thick lining may impair the marginal sealing, especially after thermocycling. It was concluded that a minimally thin flowable composite lining improved cavity adaptation and marginal sealing.

This paper proposes a new approach for combining genetic algorithm and sliding mode control to design the power system stabilizers (PSS). The design of a PSS can be formulated as an optimal linear regulator control problem. However, implementing this technique requires the design of estimators. This increases the implementation and reduces the reliability of control system. These reasons, therefore, favor a control scheme that uses only some desired state variables, such as torque angle and speed. To deal with this problem, we use the optimal reduced models to reduce the power system model into two state variables system by each generator. We use the genetic algorithm to find the switching control signals and use sliding mode control to find control signal of the generator. The advantages of the proposed method are illustrated by numerical simulation of the multi-machine power systems.

The socket liner plays a crucial role in redistribution of the interface stresses between the stump and the socket, so that the peak interface stress could be reduced. However, how the peak stress is affected by various liner stiffnesses is still unknown, especially when the phenomenon of the stump slide within the socket is considered. This study employed nonlinear contact finite element analyses to study the biomechanical reaction of the stump sliding with particular attention to the liner stiffness effects of the trans-tibial prosthesis. To validate the finite element outcomes, experimental measurements of the interface stresses and sliding distance were further executed. The results showed that the biomechanical response of the stump sliding are highly nonlinear. With a less stiff liner, the slide distance of the stump would increase with a larger contact area. However, this increase in the contact area would not ensure a reduction in the peak interface stress and this is due to the combined effects of the non-uniform shape of the socket and the various sliding distances generated by the different liner stiffnesses.

To evaluate the ability of various lining materials to reduce cervical marginal microleakage and internal voids within Class II resin-based composite restorations.168 extracted molars were prepared with both moderate and deep Class II cavities. The teeth were then randomly divided into 14 groups and restored with direct composite or sandwich techniques using various lining materials [flowable composites, compomers and resin-modified glass-ionomer cements (RMGI)]. Following restoration, the teeth were stored for 24 hours, thermocycled, and placed in fuchsin dye for 24 hours. Subsequently, the teeth were sectioned in halves and observed through a stereomicroscope. Cervical microleakage and internal voids were assessed separately as the length ratio of dye penetration to the cervical wall and the area ratio of voids to sectioned restorations. The data were analyzed with one-way ANOVA.Flowable composite lining groups demonstrated either similar or more cervical microleakage than did their respective direct restoration groups. Groups lined with RMGIs showed similar or better marginal sealing than did their resin restoration groups. In deep cavities, Vivaglass Liner group showed the best marginal sealing. RMGI-lined groups exhibited more internal voids in deep restorations.

This study used finite element simulation to investigate the load transfer mechanisms within the screw/vertebra complex under different interface conditions, and under varying screw lengths. Both bonded and contact conditions were employed to demonstrate the interface between the screw and vertebra. Loadings were applied at the superior surface of the vertebra and screw unthreaded end, respectively, to represent two modes of flexion loads. The results indicated that the screw within the vertebra underwent a series of discontinuities of loading, identified by the localized high contact pressures, thus creating localized bending moments. The peak stress of screw was located at the junction of the screw's hub and thread, which is consistent with the location of screw failure observed in a clinical setting and the values of peak stress in the screw were proportional to the amount of moments generated by the two loading modes. The interface condition plays an important role in transferring the force within the screw/vertebra complex. A contact interface condition induces significantly higher stress in the screw than the bonded condition. Therefore providing a binding surface (with HA, or porosity coating on the screw surface) between the screw and the vertebra might be the most effective way to prevent screw failure. The influences of screw length on the peak stress in the screw become negligible when the screw is of sufficient length to extend fully into the vertebral body.

Objectives . The objective of this study was to use a three-dimensional (3-D) finite element model to investigate normal stress distribution to substantiate the tooth flexure mechanism. The study also compared the changes in the stresses by different occlusal loading sites and directions. Methods . The 3-D finite element analysis was used. A maxillary premolar was selected to construct the simulation model. The model was constructed step-by-step for convergence and validity. Seven load conditions for various load sites and different directions were simulated to the model. Results . The maximal principal stress and minimal principal stress distributions developed within the structures of seven load conditions were output and their stress distributions on z -plane at the vertical midline were shown. The peak tensile stress of the cervical area for various load conditions were compared and listed. Conclusions . This study has shown that the presence of tensile stresses in the cervical region of a maxillary premolar by various loading sites and different directions. The results coincided with the stress-induced theory, hence sustaining it. The relationship of the affected factors of leverage to the development of cervical abfraction lesions, was explored.

The chin cup has been used to treat skeletal mandibular prognathism in growing patients for 200 years. The pull on the orthopedic-force chin cup is oriented along a line from the mandibular symphysis to the mandibular condyle. Various levels of success have been reported with this restraining device. The vertical chin cup produces strong vertical compression stress on the maxillary molar regions when the direction of traction is 20 degrees more vertical than the chin-condyle line. This treatment strategy may prevent relapse due to counter-clockwise rotation of the mandible. In this report, we describe a new strategy for using chin-cup therapy involving thin-plate spline (TPS) analysis of lateral cephalometric roentgenograms to visualize transformation of the mandible. The actual sites of mandibular skeletal change are not detectable with conventional cephalometric analysis. A case of mandibular prognathism treated with a chin cup and a case of dental Class III malocclusion without orthodontic treatment are described. The case analysis illustrates that specific patterns of mandibular transformation are associated with Class III malocclusion with or without orthopedic therapy, and that visualization of these deformations is feasible using TPS graphical analysis.

This study reports a method for controlling loads on an in vivo dental implant and its application for the investigation of early loading versus delayed loading of dental implants. The method was developed for the purpose of studying an ongoing hypothesis that amounts to bone loss around dental implants are related to mechanical-mediated adaptation of the alveolar bone. Using a customized intra-oral hydraulic system, the daily loading over a dental implant has been completed and recorded for six Sinclair swine. Each pig had a 5-month duration implant loading. During the experiments (loading), no analgesic treatment was supplied. The mean of the in vivo daily loadings was confirmed through an in vitro bench test after each animal was euthanized. Variations of the averaged loading input among the six animals were smaller than 10%. Preliminary data produced by the model suggests that cervical bone loss is less for early loading than for delayed loading. The current system is expected to provide a useful load control model for the study of alveolar bone adaptation around dental implants in relation to various loadings.

There are disadvantages, especially from biomechanical viewpoint, to treating idiopathic scoliosis (IS) patients using traditional Boston braces with pressure pads. The major problem is the higher stiffness of the pressure pad as compared to the soft-tissue of the trunk. The aim of this study was to evaluate the effectiveness of Boston braces in which the pressure pad was replaced by the deformable airbag. A custom-made airbag brace which was designed based on the three-point compression principle of the Boston brace was prescribed to each of the 20 IS subjects with a mean age of 11.8 ± 2.8 years old. To evaluate the effectiveness of the treatment, the scoliosis Cobb angles before the treatment and after a follow-up period were measured from AP X-rays. The mean follow-up period was 11.5 ± 6.6 months. In addition, three interface parameters — contact pressure, contact area, and contact force — under seven postures — upright, flexion, extension, left side bending, right side bending, left side rotation and right side rotation — were measured using pressure mats to investigate interface conditions between airbags and skin. During the follow-up, all scoliosis curves showed Cobb angle reduction except one thoracic curve, which increased by one degree. The Cobb angle in the thoracic region decreased from 37.3 ± 10.6° to 27.3 ± 10.1° with a mean decreasing of 9.9 ± 5.9°. The Cobb angle in the lumbar region decreased from 30.1 ± 6.9° to 17.7 ± 8.6° with a mean decreasing of 12.4 ± 4.9°. Changes in the three interface parameters for the seven postures were insignificant. This indicated that the airbag brace could provide sufficient continuous corrective force. Using the airbag, instead of the pressure pad to provide the corrective force in the brace system can effectively correct the spinal curve caused by scoliosis. Easy adjustment and direct control of airbag pressure might be the key factor to the success of the airbag brace.

The Metaphire formosae species group is a member of the Pheretima complex of the family Megascolecidae. It is composed of 12 nominal taxa, Metaphire bununa Tsai et al., 2000, Metaphire feijani Chang & Chen, 2004, Metaphire formosae (Michaelsen, 1922), Metaphire glareosa Tsai et al., 2000, Metaphire nanaoensis Chang & Chen, 2005, Metaphire paiwanna paiwanna Tsai et al., 2000, Metaphire paiwanna hengchunensis (James et al., 2005), Metaphire paiwanna liliumfordi Tsai et al., 2000, Metaphire tahanmonta Chang & Chen, 2005, Metaphire taiwanensis Tsai et al., 2004, Metaphire trutina Tsai et al., 2003, and Metaphire yuhsi (Tsai, 1964). In this study, we describe a new species, Metaphire tengjhihensis sp. nov., and two new subspecies, Metaphire nanaoensis truku ssp. nov. and Metaphire taiwanensis tsaii ssp. nov., belonging to this species group. DNA barcodes (partial sequences of the mitochondrial cytochrome c oxidase subunit 1, COI) from type specimens of M. feijani, M. tengjhihensis sp. nov., M. nanaoensis truku ssp. nov., M. tahanmonta and M. taiwanensis tsaii ssp. nov. have been deposited in GenBank in previous studies and are explicitly linked to the type specimens for the first time, enabling unambiguous identification using both morphology and DNA barcodes. Finally, we comment on the systematics of the M. formosae species group and suggest an integrative taxonomic approach that combines morphology and DNA barcodes for future descriptions of new species of Amynthas and Metaphire.

The use of an mesial-occlusal-distal (MOD) restoration in repairing a large carious lesion depends on many factors. Biomechanical performance is one of the most important. It has been recognized that resistance to restoration failure is not solely a biological concern (e.g. toxicity), but that the cavity shape, dimensions, and the state of stress must all be taken into account. In the present study, a newly developed auto-mesh program was used to generate 30 three-dimensional (3D) finite element (FE) models simulating the biomechanics for multiple factorial design of the MOD gold restoration in a maxillary second premolar. Stress levels were related to individual design factors (e.g. pulpal wall depth [P], isthmus width [W] and interaxial thickness [T]) and to their interactions under the worst physiological scenario: a concentrated bite force acting on lingual cusp with debonded interfaces between cavity walls and restorations. The results showed that enlarging the volume of the MOD cavity significantly increased stresses in enamel but did not intentionally affect stresses in dentin. The alternation of individual design parameters significantly changed the peak stresses (P < 0.05). For all three parameters, except for the width, the peak stress increased as the cavity dimension increased. Stress elevation rate (termed as 'volumetric stress rate'--stress elevation by increasing one unit volume of the restored materials) was different among three design factors. Depth was the most critical factor governing the stress elevation in enamel (1.76 MPa mm(-3)) while length (interaxial thickness) was the most important parameter in dentin (0.49 MPa mm(-3)). Width was the least compromising factor to the remaining tooth, 0.32 MPa mm(-3) for enamel and -0.23 MPa mm(-3) for dentin. The findings, at its core, did not fully agree with the traditional concept that the preservation of tooth substances will reduce risk of tooth fracture. This study leaves open possibility for the structural optimization of the MOD restoration.

Many researches have addressed the high correlation between the fracture of restored teeth and the prepared cavity geometry. In addition, concerns about bonding versus debonding dental materials from cavity walls and different occlusal force conditions could also alter the mechanical responses in a restored tooth. This study employed an automatic mesh procedure to investigate the mechanical interactions between different interfacial conditions and cavity parameters such as pulpal wall depth under different chewing functions. The results indicated that when occlusal force was applied directly on the tooth, it could increase unfavourable stress dramatically. When interfacial fixation was simulated as the contact condition between the tooth tissue and restorative material, it might increase the fracture potential exponentially compared with the bonded interface. For pulpal wall depth analyses, greater risks of fracture for the remaining tooth were observed in deeper cavity of mesio-occlusal-distal (MOD) restorations and the existence of a pulpal wall is essential even it is only 1 mm above the gingival wall.

This paper describes a new in vitro experimental model that records temperature changes over a culture plate, which then can be used to assess the biological effects of cryosurgery. A cryoprobe and 16 thermocouples set up by a computer control system were used to monitor the temperature changes during freezing and thawing in a culture plate, and the data were used to create a temperature profile of the entire plate. Location of the thermocouples was confirmed by a digital camera viewing from under the plate, and temperature changes at any point in the interpolated areas were estimated using a curve fitting method. The estimated temperature was checked by sampling with four additional randomly placed thermocouples. Linear regression analysis showed that the estimated temperature and measured temperature were very close (correlation coefficients 0.98-0.99). MBT-2 tumor cells were cultured and then subjected to simulated cryosurgery. The surviving cells were stained with crystal violet and the cell death boundary was detected by image processing. Temperature history at the cell death boundary was retrieved and analyzed. With this system it is possible to recreate the temperature changes that result in a certain biological effect (such as cell death) during the process of simulated cryosurgery.

The concept of stress-induced cervical lesions has been discussed widely in recent years. In this study, a three-dimensional finite element model was established to analyze the stress distribution at cervical region and evaluate the stresses on the interface of different restorative materials. The results indicated that tensile stress might be the major cause for tooth cervical lesion. For different restorative materials, the elastic modulus was not the key issue in premature loss of restorative material. The bonding strength between the restorative material and lesions could be the important factor for the retention failure.