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Computer Methods and Programs in... Jan 2021Magnetic resonance (MR) imaging is increasingly used in studies of speech as it enables non-invasive visualisation of the vocal tract and articulators, thus providing...
BACKGROUND AND OBJECTIVE
Magnetic resonance (MR) imaging is increasingly used in studies of speech as it enables non-invasive visualisation of the vocal tract and articulators, thus providing information about their shape, size, motion and position. Extraction of this information for quantitative analysis is achieved using segmentation. Methods have been developed to segment the vocal tract, however, none of these also fully segment any articulators. The objective of this work was to develop a method to fully segment multiple groups of articulators as well as the vocal tract in two-dimensional MR images of speech, thus overcoming the limitations of existing methods.
METHODS
Five speech MR image sets (392 MR images in total), each of a different healthy adult volunteer, were used in this work. A fully convolutional network with an architecture similar to the original U-Net was developed to segment the following six regions in the image sets: the head, soft palate, jaw, tongue, vocal tract and tooth space. A five-fold cross-validation was performed to investigate the segmentation accuracy and generalisability of the network. The segmentation accuracy was assessed using standard overlap-based metrics (Dice coefficient and general Hausdorff distance) and a novel clinically relevant metric based on velopharyngeal closure.
RESULTS
The segmentations created by the method had a median Dice coefficient of 0.92 and a median general Hausdorff distance of 5mm. The method segmented the head most accurately (median Dice coefficient of 0.99), and the soft palate and tooth space least accurately (median Dice coefficients of 0.92 and 0.93 respectively). The segmentations created by the method correctly showed 90% (27 out of 30) of the velopharyngeal closures in the MR image sets.
CONCLUSIONS
An automatic method to fully segment multiple groups of articulators as well as the vocal tract in two-dimensional MR images of speech was successfully developed. The method is intended for use in clinical and non-clinical speech studies which involve quantitative analysis of the shape, size, motion and position of the vocal tract and articulators. In addition, a novel clinically relevant metric for assessing the accuracy of vocal tract and articulator segmentation methods was developed.
Topics: Adult; Deep Learning; Dental Articulators; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Speech
PubMed: 33197740
DOI: 10.1016/j.cmpb.2020.105814 -
BMC Oral Health Oct 2020Fully adjustable articulators and pantographs record and reproduce individual mandibular movements. Although these instruments are accurate, they are operator-dependant...
BACKGROUND
Fully adjustable articulators and pantographs record and reproduce individual mandibular movements. Although these instruments are accurate, they are operator-dependant and time-consuming. Pantographic recording is affected by inter and intra operator variability in the individuation of clinical reference points and afterwards in reading pantographic recording themselves. Finally only border movements can be reproduced.
METHODS
Bionic Jaw Motion system is based on two components: a jaw movement analyzer and a robotic device that accurately reproduces recorded movements. The jaw movement analyzer uses an optoelectronic motion system technology made of a high frequency filming camera that acquires 140frames per second and a custom designed software that recognizes and determines the relative distance at each point in time of markers with known geometries connected to each jaw. Circumferential modified retainers connect markers and do not cover any occlusal surfaces neither obstruct occlusion. The recording process takes 5 to 10 s. Mandibular movement performance requires six degrees of freedom of movement, 3 rotations and 3 translations. Other robots are based on the so-called delta mechanics that use several parallel effectors to perform desired movements in order to decompose a complex trajectory into multiple more simple linear movements. However, each parallel effector introduces mechanical inter-component tolerances and mathematical transformations that are required to transform a recorded movement into the combination of movements to be performed by each effector. Bionic Jaw Motion Robot works differently, owing to three motors that perform translational movements and three other motors that perform rotations as a gyroscope. This configuration requires less mechanical components thus reducing mechanical tolerances and production costs. Both the jaw movement analyzer and the robot quantify the movement of the mandible as a rigid body with six degrees of freedom. This represents an additional advantage as no mathematical transformation is needed for the robot to reproduce recorded movements.
RESULTS
Based on the described procedure, Bionic Jaw Motion provide accurate recording and reproduction of maxillomandibular relation in static and dynamic conditions.
CONCLUSION
This robotic system represents an important advancement compared to available analogical and digital alternatives both in clinical and research contexts for cost reduction, precision and time saving opportunities.
Topics: Dental Articulators; Jaw Relation Record; Mandible; Movement; Reproduction; Robotics
PubMed: 33028288
DOI: 10.1186/s12903-020-01257-6 -
Journal of Prosthodontics : Official... Feb 2021Mounting dental casts in an articulator is an important prerequisite for prosthodontic rehabilitation cases where the design of an accurate static and dynamic occlusion...
Mounting dental casts in an articulator is an important prerequisite for prosthodontic rehabilitation cases where the design of an accurate static and dynamic occlusion is needed. Virtual mounting can be achieved through the superimposition of various 3D images acquired from the hard and soft tissues of the patient. The purpose of this technical report is to describe a digital cross-mounting technique for patients undergoing implant-supported fixed prosthetic treatment. Through the use of face scanning, intraoral scanning, and cone beam computed tomography, this technique enables creation of a 3D virtual patient with occlusal registration in centric relation. Ultimately, the described methodology allows for the fabrication of definitive full-mouth implant-supported fixed prostheses.
Topics: Computer-Aided Design; Cone-Beam Computed Tomography; Dental Articulators; Dental Implants; Humans; Workflow
PubMed: 32865872
DOI: 10.1111/jopr.13247 -
Journal of Prosthodontics : Official... Jan 2021A virtual articulator is a computer software tool that is capable of reproducing the relationship between the jaws and simulating jaw movement. It has gradually gained... (Review)
Review
A virtual articulator is a computer software tool that is capable of reproducing the relationship between the jaws and simulating jaw movement. It has gradually gained research interest in dentistry over the past decade. In prosthodontics, the virtual articulator should be considered as an additional diagnostic and treatment planning tool to the mechanical articulator, especially in complex cases involving alterations to the vertical dimension of occlusion. Numerous authors have reported on the available digital methodologies used for the assembly of virtual arch models in a virtual articulator, focusing their attention on topics such as the virtual facebow and digital occlusal registration. To correctly simulate jaw movement, the jaw models have to be digitalized and properly mounted on the virtual articulator. The aim of this review was to discuss the current knowledge surrounding the various techniques and methodologies related to virtual mounting in dentistry, and whether virtual articulators will become commonplace in clinical practice in the future. This review also traces the history of the virtual articulator up to its current state and discusses recently developed approaches and workflows for virtual mounting based on current knowledge and technological devices.
Topics: Dental Articulators; Dental Occlusion; Jaw Relation Record; Models, Dental; Patient Care Planning; Prosthodontics; Vertical Dimension
PubMed: 32827222
DOI: 10.1111/jopr.13240 -
Journal of Prosthodontics : Official... Aug 2020The virtual patient, a unique computer simulation of the patient's face, teeth, oral mucosa, and bone, provides an extraordinary mechanism for digital dental implant...
The virtual patient, a unique computer simulation of the patient's face, teeth, oral mucosa, and bone, provides an extraordinary mechanism for digital dental implant surgery planning and prosthetic design. However, the seamless registration of digital scans with functional information in the context of a virtual articulator remains a challenge. This report describes the treatment of a 47-year-old male with full-mouth guided immediate implant placement and immediate loading of CAD/CAM interim prostheses. Utilizing a novel digital workflow, a multifactorial registration of the vertical dimension of occlusion, centric occlusion, and facebow record were completed digitally and paired within a digital articulator. Utilizing this innovative approach, a complex treatment plan and procedure was executed smoothly with a successful prosthetic outcome demonstrating good fit, occlusion, esthetics, and patient reported satisfaction.
Topics: Computer Simulation; Computer-Aided Design; Dental Articulators; Dental Implants; Dental Prosthesis, Implant-Supported; Esthetics, Dental; Humans; Male; Middle Aged
PubMed: 32424940
DOI: 10.1111/jopr.13204 -
Computer Methods in Biomechanics and... Jul 2020The location of the terminal hinge axis of the temporomandibular joint is still a very wide-spread procedure in dentistry in order to replicate the movement in various...
The location of the terminal hinge axis of the temporomandibular joint is still a very wide-spread procedure in dentistry in order to replicate the movement in various articulator devices. Especially pantographic methods are claimed to provide accurate measurements and, additionally, are seen to be able to separate a pure rotation of the joint from a movement with an arbitrary combined shift and rotation. In the latter application, these methods were used in a lot of studies as a reference standard. The aim of this study was to analyze, whether common pantographic methods in general are able to distinguish between a pure rotation and a movement with rotational and translational portions. The mathematical proof of this analysis was done with theoretical kinematic considerations and compared with computer simulations. The results show for the first time that there exist combinations of rotational and translational movements of the temporomandibular joint which cannot be separated from pure rotational movements using actual pantographic methods. Even more, the consequence is a shifted location of the (combined) finite center (axis) of rotation in comparison to the true center (axis) of rotation: in case of a translational portion of only 1 mm, this is a displacement of around ±6 mm and, in case of 2 mm translation, a displacement of ±12 mm. This finding necessitates a critical reinterpretation of former studies using pantographic methods as a reference standard. Further, under some circumstances it may also affect the applicability of articulator concepts and the interpretation of functional signs.
Topics: Biomechanical Phenomena; Computer Simulation; Humans; Mandible; Movement; Rotation; Temporomandibular Joint
PubMed: 32116047
DOI: 10.1080/10255842.2020.1724975 -
Journal of Indian Prosthodontic Society 2020Identification and establishment of the occlusal plane in patients with impaired occlusal plane, presents a major hurdle for the execution of natural esthetics, speech,...
AIMS
Identification and establishment of the occlusal plane in patients with impaired occlusal plane, presents a major hurdle for the execution of natural esthetics, speech, and function. The aim of this study was to minimize such errors while occlusal rehabilitation, and employ hamular notchincisive papilla (H.I.P) plane as landmark and scribe it on the cast using H. I. P evaluator and utilise for occlusal corrections.
SETTINGS AND DESIGN
HIP plane being parallel to the occlusal plane could ease the operator when it could be scribed on cast to analyze and restore the compromised occlusal plane.
MATERIALS AND METHODS
Dentulous casts of two hundred participants were mounted on the Hanau Wide-Vue articulator. Reference points were marked on the maxillary right central incisor and maxillary molars on casts for attaining different occlusal planes, the incisive papilla and hamular notch region were also marked for HIP plane. A plane parallel HIP was scribed on cast using HIP Evaluator. The casts were then scanned using a three-dimensional coordinate measuring machine attached to perception V5 laser scanner and measurements were made using Geomagic X design software. The most parallel occlusal plane to HIP plane was evaluated, and the reliability of HIP evaluator was verified.
STATISTICAL ANALYSIS USED
ANOVA test, -Bonferroni test, and independent sample ""-test were carried out for the comparison between occlusal planes, among the genders and for the analysis of the angle of deviation of scribed plane on the cast to HIP plane on the right and left sides.
RESULTS
Occlusal plane III (Mesio-labial incisal edge of upper right central incisor to Mesio-buccal cusp tips of upper second molars) showed least angle of deviation with 1.316° ± 1.158° to HIP plane among tested subjects. There is no significant difference between the genders. The plane scribed on the cast with H. I. P evaluator showed relative parallelism to H. I. P plane with minimum deviation of 0.010° ± 0.363°.
CONCLUSION
Occlusal plane III is more parallel to H. I. P plane. Scribed plane on the cast using H. I. P evaluator is parallel to H. I. P plane. H. I. P evaluator can be used as an alternative tool to establish the occlusal plane to rehabilitate patient with deficient dentition or disordered occlusal plane.
PubMed: 32089600
DOI: 10.4103/jips.jips_167_19 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Feb 2020To evaluate the three-dimensional (3D) reconstruction accuracy of the intercuspal occlusion (ICO) of the dental casts, by the dental articulator position method, and...
OBJECTIVE
To evaluate the three-dimensional (3D) reconstruction accuracy of the intercuspal occlusion (ICO) of the dental casts, by the dental articulator position method, and provide a reference for clinical application.
METHODS
The standard dental casts in ICO were mounted on average values articulator, and five pairs of milling resin cylinders were respectively attached to the base of both the casts. 100 μm articulating paper and occlusal record silicone rubber were used to detect the occlusal contact number between the posterior teeth of casts mounted on articulator in ICO. The occlusal contact numbers NA detected by the two methods were calculated simultaneously, as the reference. After the upper and lower casts were scanned separately, and the buccal data of casts in ICO were scanned with the aid of the dental articulator position, registration was carried out utilizing the registration software. Then the digital casts mounted in ICO as well as the buccal occlusal data were saved in standard tessellation language (STL) format. Geomagic Studio 2013 software was used to analyze the contact number NS between digital upper and lower casts by the "deviation analysis" function. The differences were compared between N and N, to evaluate the sensitivity and positive predict value (PPV) of the model scanner to reproduce the occlusal contact with the aid of dental articulator position. The distance D between the centers of the circles at the top surface of the upper and lower corresponding cylinders was obtained by the three-coordinate measuring system Faro Edge, as the reference value. The Geomagic Studio 2013 software was used to construct the cylinders of digital casts and the distance D between the centers of the circles at the top surface of the corresponding cylinders were measured, as the test value. The one-sample T test was used to analyze the variable differences between D and D.
RESULTS
The PPV of reproducing the occlusal contact point was 0.76 and sensitivity was 0.81. The distance error of the opposite cylinder was (0.232±0.089) mm. There was no statistical difference between the feature points 5-5', while there were statistical differences between the other feature points.
CONCLUSION
By the dental articulator position method, the model scanner reproduces the occlusal contact point with high sensitivity and PPV, and that meets clinical needs. Meanwhile, the distance between the feature points is greater than the reference value, which will lead to occlusal disturbance, and require clinical grinding.
Topics: Dental Articulators; Dental Occlusion; Imaging, Three-Dimensional; Jaw Relation Record; Models, Dental; Software
PubMed: 32071477
DOI: 10.19723/j.issn.1671-167X.2020.01.022 -
Journal of International Society of... 2019The objectives of this study were to determine the condylar guidance by the conventional method using interocclusal records and by panoramic radiographs in healthy...
Comparison of Sagittal Condylar Guidance Determined by Panoramic Radiographs to the One Determined by Conventional Methods Using Lateral Interocclusal Records in the Saudi Arabian Population.
OBJECTIVES
The objectives of this study were to determine the condylar guidance by the conventional method using interocclusal records and by panoramic radiographs in healthy dentate patients and to compare the values obtained from panoramic radiographs with the values obtained by a conventional method.
MATERIALS AND METHODS
Thirty healthy dentulous subjects of either sex with an age range of 20-40 years visiting Jazan University, College of Dentistry, Dental Clinics for replacement of missing teeth or crowns, were selected according to the inclusion criteria. Maxillary and mandibular casts were obtained and mounted on Whipmix 2240 articulator. Right and left lateral interocclusal records were then made in patients by base plate wax (Dentsply truwax baseplate). This record was transferred to articulator, and condylar values were determined. In all the cases, articulator was programmed. Left and right condylar values were also measured on digital radiographs and readings were recorded. Condylar guidance readings obtained from interocclusal records and those obtained from panoramic radiographic images were compared and analyzed statistically using the -test.
RESULTS
The condylar guidance values obtained from the interocclusal record method for both left and right sides were less when compared to the values obtained from tracing the panoramic radiographs (radiographic method). The difference in values of both the methods was highly significant.
CONCLUSION
Although a significant amount of correlation was found between the two methods, better radiographic techniques should be further investigated.
PubMed: 32039080
DOI: 10.4103/jispcd.JISPCD_11_19 -
Contemporary Clinical Dentistry 2019This case report highlights a case of full-mouth rehabilitation in a 38-year-old female. Extrusion of the right posterior maxillary alveolar segment had resulted due to...
This case report highlights a case of full-mouth rehabilitation in a 38-year-old female. Extrusion of the right posterior maxillary alveolar segment had resulted due to the presence of an opposing edentulous mandibular span, which had led to complete absence of restorative space in the lower arch. Maxillary posterior segmental osteotomy was carried out to obtain adequate space for placing an implant-supported prosthesis in the opposing edentulous mandibular span. The procedures before the surgery consisted of articulation of the diagnostic casts on to a semi-adjustable Hanau™ Wide-Vue articulator and a mock surgery on the upper cast to assess the amount of segmental osteotomy necessary to accommodate an implant-supported prosthesis in the lower edentulous region. Other procedures included implant placements, root canal treatment, post and core build-up, and full-crown placement on various teeth.
PubMed: 32015663
DOI: 10.4103/ccd.ccd_487_18