Stereotaxic Device for Optical Imaging of Mice Hind Feet

Imaging of in vivo model systems, especially mouse models, has revolutionized our understanding of normal and pathological developments. However, mice present several challenges for imaging. They are living and therefore breathing organisms with a fast heart rate (>500 beat/min), which necessitates the need for restraints and positioning controls that do not compromise their normal physiology. We present here a device that immobilizes the rear legs of a mouse while retaining the ability to position both the hind feet and legs for reproducible imaging deep below the skin''s surface. The device is highly adjustable to accommodate mice, 5 weeks of age and older. The function of this device is demonstrated by imaging the vasculature ∼250 μm beneath the skin in the hind leg. Whereas the overall dimensions are for a motorized stage (Märzhäuser Wetzlar GmbH, Wetzlar, Germany), minor modifications would allow it to be customized for use with most commercially available stages that accept an insert.     

Optimal imaging windows of indocyanine green‐assisted near‐infrared dental imaging with rat model and its comparison to X‐ray imaging

In this study, we used rat animal model to compare the efficiency of indocyanine green (ICG)‐assisted dental near‐infrared fluorescence imaging with X‐ray imaging, and we optimized the imaging window for both unerupted and erupted molars. The results show that the morphology of the dental structures was observed clearly from ICG‐assisted dental images (especially through the endoscope). A better image contrast was easily acquired at the short imaging windows (<10 minutes) for unerupted and erupted molars. For unerupted molars, there is another optimized imaging window (48‐96 hours) with a prominent glow‐in‐the‐dark effect: only the molars remain bright. This study also revealed that the laser ablation of dental follicles can disrupt the molar development, and our method is able to efficiently detect laser‐treated molars and acquire the precise morphology. Thus, ICG‐assisted dental imaging has the potential to be a safer and more efficient imaging modality for the real‐time diagnosis of dental diseases.     

A new X-ray-free measurement method for postoperative 3D-position analysis of navigated inserted implants]

In this article a new X-ray-free measurement method for postoperative 3D-position analysis of dental implants is proposed. The advantage of this new method is the possibility of precise 3D comparison to preoperative planning data without the use of X-rays. Standard methods for postoperative implant analysis are performed manually on the basis of orthopantomography or computer tomography scans. The proposed method uses a navigation system and a specially designed measurement device. Analysis of the measurement data shows a mean position error of 0.2 mm +/-0.1 mm and a mean depth error of 0.4 mm +/- 0.3 mm. Thus, this method is suitable for postoperative analysis of the horizontal implant position and for comparison to preoperative planning     

Can a finite set of knee extension in supine position be used for a knee functional examination?

The kinematic magnetic resonance imaging technique has been developed to provide a functional examination of the knee. Technical limitations require this examination to be performed in supine position, and the knee motion is represented by an assembly of static positions at different knee angles. However, the main knee function is to support the body weight and perform continuous motion, e.g. parallel squat. Our study quantified the knee kinematics of 20 healthy subjects in different motion conditions (finite and continuous) and in different mechanical conditions (continuous unloaded and continuous loaded). We evaluated the angular and localisation difference of a finite helical axis of the knee motion for parallel squat, continuous knee extension in supine position and the finite set of knee extension in supine position. We found large inter-individual dispersion. The majority of subjects had equivalent knee kinematics between continuous knee extension and the finite set of knee extension in supine position, but not between continuous knee extension in supine position and the parallel squat. Therefore, results from a functional examination of a finite set of knee extensions in supine position do not represent the knee motion in a parallel squat. Our results suggest that functional examination of the knee from magnetic resonance imaging do not necessarily reflect the physiological kinematics of the knee. Further investigation should focus on a new magnetic resonance imaging acquisition protocol that allows image acquisition during weight bearing or includes a special device which reproduces the loaded condition.     

Does a specific MR imaging protocol with a supine-lying subject replicate tarsal kinematics seen during upright standing?

Magnetic resonance (MR) imaging is becoming increasingly important in the study of foot biomechanics. Specific devices have been constructed to load and position the foot while the subject is lying supine in the scanner. The present study examines the efficacy of such a newly developed device in replicating tarsal kinematics seen during the more commonly studied standing loading conditions. The results showed that although knee flexion and the externally applied load were carefully controlled, subtalar and talo-navicular joint rotations while lying during MR imaging and when standing (measured opto-electrically with markers attached to intracortical pins) did not match, nor were they systematically shifted. Thus, the proposed MR protocol cannot replicate tarsal kinematics seen during upright standing. It is concluded that specific foot loading conditions have to be considered when tarsal kinematics are evaluated. Improved replication of tarsal kinematics in different postures should comprehensively consider muscle activity, a fixed hip position, and a well-defined point of load application.     

Dental cone beam CT: An updated review

Cone beam computed tomography (CBCT) is a diverse 3D x-ray imaging technique that has gained significant popularity in dental radiology in the last two decades. CBCT overcomes the limitations of traditional two-dimensional dental imaging and enables accurate depiction of multiplanar details of maxillofacial bony structures and surrounding soft tissues. In this review article, we provide an updated status on dental CBCT imaging and summarise the technical features of currently used CBCT scanner models, extending to recent developments in scanner technology, clinical aspects, and regulatory perspectives on dose optimisation, dosimetry, and diagnostic reference levels. We also consider the outlook of potential techniques along with issues that should be resolved in providing clinically more effective CBCT examinations that are optimised for the benefit of the patient.     

A cloud-fog software architecture for dental CBCT dose monitoring using the DICOM structured report: Automated establishment of DRL

PurposeThe diagnostic reference level (DRL) has been established to optimize the diagnostic methods and reduce radiation dose during radiographic examinations. The aim of this study was to present a completely new solution based on Cloud-Fog software architecture for automatic establishment of the DRL values during dental cone-beam computed tomography (CBCT) according to digital imaging and communications in medicine (DICOM) structured reports.Methods and MaterialsA Cloud-Fog software architecture was used for automatic data handling. This architecture used the DICOM structured reports as a source for extracting the required information by fog devices in the imaging center. These devices transferred the derived information to the cloud server. The cloud server calculated the value of indication-based DRL in dental CBCT imaging based upon the parameters and adequate quantities of the absorbed dose. The feedback of DRL value was continuously announced to the imaging centers in 6 phases. In each phase, the level of the dose was optimized in imaging centers.ResultsThe DRL value was established for 5-specific indications, including third molar teeth (511 mGy.cm²), implant (719 mGy.cm²), form and position anomalies of the tooth (408 mGy.cm²), dentoalveolar pathologies (612 mGy.cm²), and endodontics (632 mGy.cm²). The determination of the DRL value in each phase revealed a downward trend until stabilization.ConclusionThe new solution presented in this study makes it possible to calculate and update the DRL value nationally and automatically among all centers. Also, the results showed that this approach is successful in establishing stabilized DRL values.     

Spatial relationship between the mental foramen and mandibular developing teeth in modern humans,chimpanzees, and hamadryas baboons

The mental foramen (MF) of adult human mandibles is characterized by its high position and posterosuperior opening orientation, compared with that of nonhuman primates. In this study, to examine when and how such interspecies variations in MF position/orientation are manifested in the context of dental development, positional relationships between the MF and nearby forming teeth (dc, dm1, C, P3) were assessed using CT‐scanned growth‐series mandibles of the following three species with various MF positions and anterior dental sizes: modern humans, chimpanzees, and hamadryas baboons. Results showed that modern humans have more antero‐superiorly located MF and dc than the two nonhuman samples during growth, whereas the MF and dm1 of hamadryas baboons are the most inferiorly positioned. Considering that the mandibular canal generally reaches the dc/dm1 position during infancy, the species differences in MF position can be attributed largely to the positions where the anterior deciduous teeth first appear. Specifically, the distinctive dental position of modern humans should stem eventually from the comparatively small anterior dental size. Furthermore, human MF position shifted slightly upwards with alveolar development, unlike in the nonhuman samples, accompanied by strong curvature and vertical elongation of the anterior mandibular canal. Meanwhile, the human MF shifted from a forward to a lateral/backward orientation in association with human‐specific growth‐related alveolar recession. The findings of this study, thus, collectively indicate that taxonomic variations in adult MF position/orientation can be interpreted partly by the positions of the surrounding developing teeth. Am J Phys Anthropol 154:594–603, 2014. © 2014 Wiley Periodicals, Inc.     

Variables affecting dental fluctuating asymmetry in human isolates

The aims of the present study are to 1) determine and describe levels of dental fluctuating asymmetry (FA) in a highly endogamous human group; 2) evaluate the effects of various FA measures on perceived FA levels and their interrelationships; 3) study the connections between dental variables (tooth size, class, position, type, location and dimension) and FA levels; and 4) estimate the interrelationships between dental FA measures. The study was carried out on 242 Bedouin boys aged 5 to 14 years. The results demonstrate that the main variables influencing dental FA levels within this population are tooth class (incisors, canine, premolars, molars) and position (mesial, distal) and that the interaction between the two is significant. When sample sizes are large enough and individual measures are needed for the statistical analysis, the use of a computational method based on absolute values is legitimate. Clear relationships between some FA dental traits are discerned though principal-components analysis. © 1993 Wiley-Liss, Inc.     

Confocal Time Lapse Imaging as an Efficient Method for the Cytocompatibility Evaluation of Dental Composites

It is generally accepted that in vitro cell material interaction is a useful criterion in the evaluation of dental material biocompatibility. The objective of this study was to use 3D CLSM time lapse confocal imaging to assess the in vitro biocompatibility of dental composites. This method provides an accurate and sensitive indication of viable cell rate in contact with dental composite extracts. The ELS extra low shrinkage, a dental composite used for direct restoration, has been taken as example. In vitro assessment was performed on cultured primary human gingival fibroblast cells using Live/Dead staining. Images were obtained with the FV10i confocal biological inverted system and analyzed with the FV10-ASW 3.1 Software. Image analysis showed a very slight cytotoxicity in the presence of the tested composite after 5 hours of time lapse. A slight decrease of cell viability was shown in contact with the tested composite extracts compared to control cells. The findings highlighted the use of 3D CLSM time lapse imaging as a sensitive method to qualitatively and quantitatively evaluate the biocompatibility behavior of dental composites.     

Cellular phone‐based photoplethysmographic imaging

We present study results on visible light reflection photoplethysmographic (PPG) imaging with a mobile cellular phone operated in video imaging mode. PPG signal components around 0.1 Hz attributed to the sympathetic component of the heart rate, 1 Hz as the heart rate and 2 Hz as heart rate high order harmonic were quantified on the index finger of a healthy volunteer. The green channel reported PPG signals throughout the sampled area. The blue and red channel returned plethysmographic information, but the signal strength was highly position specific. Our results obtained with a cellular phone as the data acquisition device are encouraging, especially in the broad context of personal or home‐based care and the role of cellular phone technology in medical imaging. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Familial similarity in dental arch form and tooth position.

This study was done to quantify and compare similarities in dental arch form and tooth position among individuals of various degrees of biological kinship. The sample consisted of 360 dental casts selected from 102 Japanese families, each including both parents and one of their offspring. Most of the subjects had well-aligned permanent dentitions. Coefficients of dissimilarity were obtained by orienting two standard-sized dental arch diagrams plotted from occlusal photographs to the position of best fit. Dissimilarity between adults and children from different families was computed and served as the control data. With few exceptions, the mean dissimilarity between parents and offspring was smaller than that of the nonfamilial pairings; however, statistical differences were not always significant. Among all the teeth observed, the position of both upper and lower central incisors was found to exhibit the least familial similarity. Analysis of variance among pairings of different sources of variation suggested the existence of significant additive genetic effect, both autosomal and sex-linked. Relative contribution of the additive genetic effect in the total variability of this sample was estimated for dental arch form and tooth position to be in the range of 55-60% and 39-77%, respectively. Autosomal additive genetic effects appear to strongly account for the variation in position of the second premolar and of the first molar.     

A new dental unit for both patients in wheelchairs and general patients

Objective: To develop a dental unit to accommodate both patients in wheelchairs and general patients, and to evaluate the acceptability of the new chair for patients and dentists. Design: To integrate a unit for patients in wheelchairs and a unit for general patients into a single dental unit. Results: (1) The newly developed dental unit could be used for both patients in wheelchairs and general patients and could be installed in nearly the same space as occupied by a conventional dental unit. (2) The dentists could take the home position because of the height‐adjusting and tilting mechanisms. (3) The patients could be treated with a sense of assurance because of the wheelchair immobilizer and the safety devices. (4) The dentists could perform patient treatment safely. (5) As patients did not need to be transferred from their wheelchairs, assistance was unnecessary. (6) From the questionnaires, both patients and dentists rated the newly developed dental unit favourable. Conclusions: The new dental unit for patients in wheelchairs and general patients permitted dentists to perform and patients to receive dental treatment safely and in a comfortable position. Also, as a single unit could be used for treatment of both types of patients, it required no extra space. Therefore, it has the potential to be installed in the clinics of general dental practitioners to treat both groups of patients.     

The Use of a Respiratory Rate Biofeedback Device to Reduce Dental Anxiety: An Exploratory Investigation

Anxiety experienced by individuals visiting the dental office to receive treatment is common. Evidence has shown biofeedback to be a useful modality of treatment for numerous maladies associated with anxiety. The purpose of the current pilot study was to investigate the use of a novel biofeedback device (RESPeRATE™) to reduce patients’ pre-operative general anxiety levels and consequently reduce the pain associated with dental injections. Eighty-one subjects participated in this study, forty in the experimental group and forty-one in the control group. Subjects in the experimental group used the biofeedback technique, while those in the control group were not exposed to any biofeedback. All subjects filled out a pre-injection anxiety survey, then received an inferior alveolar injection of local anesthetic. Post-injection, both groups were given an anxiety survey and asked to respond to four questions regarding the injection experience using a Visual Analog Scale (VAS). With the use of the respiratory rate biofeedback device, there was a significant reduction of negative feelings regarding the overall injection experience, as measured by a VAS. Our findings demonstrate that this novel biofeedback technique may be helpful in the amelioration of dental anxiety, and may help produce a more pleasant overall experience for the patient.     

Kinematic study of the mandible using an electromagnetic tracking device and custom dental appliance: introducing a new technique

The purpose of this study is to introduce a new technique for recording the kinematics of the temporomandibular joint and incisors, using an electromagnetic tracking device and custom dental appliance. Five normal subjects took part in this kinematic study (4 females, 1 male, mean age of 34.8 years). Subjects' mandibular motion during maximal opening tasks were recorded on two different days and linear distance (LD) (i.e., the LD between the start and end position) and curvilinear path (CP) (i.e., the curvilinear distance along the curve between the start and end position) were calculated for the lower incisor landmark and both condyles in the sagittal plane (in mm). In the present study, the range of incisal movements (LD: 34.9 to 54.3 mm, CP: 36.5 to 60.3 mm) and that of condylar movements (LD: 7.5 to 25.3 mm, CP: 10.6 to 27.6 mm) in the sagittal plane during opening are in the normal range compared to the previous literature. The ability of subjects to reproduce the same motion between the two sessions was also calculated. Differences due to trial sessions and different repetitions within a session were negligible, indicating that the method can be used to assess changes between testing conditions in healthy subjects, and patients pre- and post-operatively.     

Neural crest contribution to mammalian tooth formation

The cranial neural crest cells, which are specialized cells of neural origin, are central to the process of mammalian tooth development. They are the only source of mesenchyme able to sustain tooth development, and give rise not only to most of the dental tissues, but also to the periodontium, the surrounding tissues that hold teeth in position. Tooth organogenesis is regulated by a series of interactions between cranial neural crest cells and the oral epithelium. In the development of a tooth, the epithelium covering the inside of the developing oral cavity provides the first instructive signals. Signaling molecules secreted by the oral epithelium 1) establish large cellular fields competent to form a specific tooth shape (mono- or multicuspid) along a proximodistal axis; 2) define an oral (capable of forming teeth) and non-oral mesenchyme along a rostrocaudal axis; and 3) position the sites of future tooth development. The critical information to model tooth shape resides later in the neural crest-derived mesenchyme. Cranial neural crest cells ultimately differentiate into highly specialized cell types to produce mature dental organs. Some cranial neural crest cells located in the dental pulp, however, maintain plasticity in their developmental potential up to postnatal life, offering new prospects for regeneration of dental tissues.     

Ontogeny, anatomy and attachment of the dentition in mosasaurs (Mosasauridae: Squamata)

Aspects of mosasaur dental ontogeny are well preserved in many fossils of these giant marine squamates. Replacement teeth on the tooth-bearing elements (TBEs) first appear as small enamel crowns positioned posterolingual to the attached tooth (posterolabial for the pterygoid). Several developing crowns, of progressively larger size, are aligned in rows relating to a specific tooth position. The crowns rest in a dental groove that varies in width and depth depending on the TBE. The crown closest to the attached tooth is always the largest and is found in a small resorption pit. As resorption proceeds, the pit expands in volume (cementum and alveolar bone), and the crown increases in size and settles into the pit. Once mature crown size is achieved, the dentine root and cementum portion of the root develop rapidly, the attached tooth is lost and the replacement tooth erupts out of the alveolus. Mosasaurid teeth develop along a 'zig-zag'-shaped movement path: horizontally along the dental groove, down into the alveolus, and up and out of the alveolus prior to attachment to the alveolar wall. At no point in mosasaurid tooth development are the crowns observed in a horizontal position. The mosasaurid dental lamina appears to have been a continuous strip of dental epithelium as it is in other squamates. Mosasaurid tooth attachment is thecodont (histologically and geometrically) not subpleurodont. Most aspects of mosasaurid tooth attachment and ontogeny are autapomorphic for the group.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 149 , 687–700.     

Simple and Versatile 3D Printed Microfluidics Using Fused Filament Fabrication

The uptake of microfluidics by the wider scientific community has been limited by the fabrication barrier created by the skills and equipment required for the production of traditional microfluidic devices. Here we present simple 3D printed microfluidic devices using an inexpensive and readily accessible printer with commercially available printer materials. We demonstrate that previously reported limitations of transparency and fidelity have been overcome, whilst devices capable of operating at pressures in excess of 2000 kPa illustrate that leakage issues have also been resolved. The utility of the 3D printed microfluidic devices is illustrated by encapsulating dental pulp stem cells within alginate droplets; cell viability assays show the vast majority of cells remain live, and device transparency is sufficient for single cell imaging. The accessibility of these devices is further enhanced through fabrication of integrated ports and by the introduction of a Lego^®-like modular system facilitating rapid prototyping whilst offering the potential for novices to build microfluidic systems from a database of microfluidic components.     

Growth changes in measurements of upper facial positioning

Growth changes in the position of the midline upper face are examined for samples of Pan troglodytes, Gorilla gorilla, and modern humans. Horizontal and vertical distances between nasion and the anterior end of the cribriform plate are plotted against stage of dental development. Kendall's nonparametric correlations between facial positioning and stage of dental development are tested for significance. In African apes, the upper face becomes more projecting and positioned higher relative to the anterior cranial base. The extent of this horizontal and vertical separation reflects primarily facial size. In modern humans, the upper face becomes more projecting but is relatively stable in its vertical position. Comparison of Pan and modern human crania in the youngest dental age category indicates that the upper face of modern humans is positioned lower early in postnatal life. The position of the upper face (glabella) relative to the anterior and posterior cranial base is presented for several fossil hominid crania. The fossil crania are similar to Pan and modern humans in facial projection relative to the anterior cranial base. However, glabella is positioned low in the fossil crania. Total facial projection (relative to hormion) for Sts 5 is similar to the mean for Gorilla. Fossil Homo and robust australopithecine crania display very projecting upper faces. We suggest that the upper face of Homo is projecting due to the length of the anterior cranial fossa, while robust australopithecines possess a thick frontal bone.     

A practical device for pinpoint delivery of molecules into multiple neurons in culture

We have developed a device for pinpoint delivery of chemicals, proteins, and nucleic acids into cultured cells. The principle underlying the technique is the flow of molecules from the culture medium into cells through a rupture in the plasma membrane made by a needle puncture. DNA transfection is achieved by stabbing the needle tip into the nucleus. The CellBee device can be attached to any inverted microscope, and molecular delivery can be coupled with conventional live cell imaging. Because the position of the needle relative to the targeted cultured cells is computer-controlled, efficient delivery of molecules such as rhodamine into as many as 100 HeLa cells can be completed in 10 min. Moreover, specific target cells within a single dish can be transfected with multiple DNA constructs by simple changes of culture medium containing different plasmids. In addition, the nano-sized needle tip enables gentle molecular delivery, minimizing cell damage. This method permits DNA transfection into specific hippocampal neurons without disturbing neuronal circuitry established in culture.