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Journal of Prosthodontics : Official... Apr 2021The purpose of this Critically Appraised Topic was to investigate the possible clinical relevance of recording the immediate mandibular lateral translation. (Review)
Review
PURPOSE
The purpose of this Critically Appraised Topic was to investigate the possible clinical relevance of recording the immediate mandibular lateral translation.
MATERIALS AND METHODS
A literature search limited to Clinical trials, Randomized Controlled Trials, Systematic Reviews, Meta Analyses, and using the PICO headings revealed no citations. Using the key words dental, occlusion, immediate side shift, also received no citations. Expanding the search criteria to include Journal Articles revealed 17 citations. Using dental occlusion, Bennett movement, revealed 21 citations.
RESULTS
The cited articles were reviewed for relevance and duplicates were eliminated. The resulting 10 English language in vivo studies pertinent to the question were included. Other articles were culled from the author's library and the reference list of the aforementioned articles. There is no evidence on the prevalence of IMLT in patients in need of occlusal rehabilitation. There is agreement that the recording of the IMLT is reference point and recording instrument dependent. There is agreement that IMLT is observable on some patients and is minimal in magnitude. There is no evidence of any adverse clinical events as a result of not including IMLT in a restorative occlusal scheme.
CONCLUSIONS
It is justifiable to question the necessity of attempting both to record immediate mandibular lateral translation on the average patient and reproduce it on an articulator.
Topics: Dental Articulators; Humans; Mandible; Movement
PubMed: 33783092
DOI: 10.1111/jopr.13317 -
The Journal of Prosthetic Dentistry Feb 2023Alternatives to the bilateral interocclusal registration scanning technique to improve virtual articulation have not been fully investigated.
STATEMENT OF PROBLEM
Alternatives to the bilateral interocclusal registration scanning technique to improve virtual articulation have not been fully investigated.
PURPOSE
The purpose of this in vitro study was to compare the accuracy of virtually articulating digital casts by using bilateral interocclusal registration scans versus a complete arch interocclusal scan.
MATERIAL AND METHODS
A set of maxillary and mandibular reference casts were hand-articulated and mounted on an articulator. The mounted reference casts were scanned, and the maxillomandibular relationship record was scanned 15 times using 2 different scanning techniques, the bilateral interocclusal registration scan (BIRS) and complete arch interocclusal registration scan (CIRS), with an intraoral scanner. The generated files were transferred to a virtual articulator, and each set of scanned casts was articulated using BIRS and CIRS. The virtually articulated casts were saved as a set and transferred to a 3-dimensional (3D) analysis program. The scanned casts were set in the same coordinate system as the reference cast and overlaid on top of the reference cast for analysis. Two anterior and 2 posterior points were selected to determine points of comparison between the reference cast and test casts virtually articulated with BIRS and CIRS. The mean discrepancy between the 2 test groups and the anterior and posterior mean discrepancy within each group were tested for significance by using the Mann-Whitney U test (α=.05).
RESULTS
A significant difference was found between the virtual articulation accuracy of BIRS and CIRS (P<.001). The mean deviation for BIRS was 0.053 ±0.051 mm and that for CIRS was 0.265 ±0.241 mm. Furthermore, significant differences were found between the anterior and posterior deviations in both BIRS (P=.020) and CIRS (P<.001). The mean deviation for BIRS was 0.034 ±0.026 mm in the anterior and 0.073 ±0.062 mm in the posterior. The mean deviation for CIRS was 0.146 ±0.108 mm anteriorly and 0.385 ±0.277 mm posteriorly.
CONCLUSIONS
BIRS was more accurate than CIRS for virtual articulation. Moreover, the alignment accuracy of anterior and posterior sites for both BIRS and CIRS exhibited significant differences, with the anterior alignment exhibiting better accuracy in relation to the reference cast.
PubMed: 36813588
DOI: 10.1016/j.prosdent.2023.01.028 -
Journal of Clinical Medicine May 2022During prosthodontic treatment, the averaged values of the transversal condylar inclination (TCI) and the sagittal condylar inclination (SCI) are used for articulator...
BACKGROUND
During prosthodontic treatment, the averaged values of the transversal condylar inclination (TCI) and the sagittal condylar inclination (SCI) are used for articulator settings. This study evaluated different parameters of measurable mandibular movements according to skeletal classes.
METHODS
Seventy-five patients (mean age 30.8 ± 5.49) had a condylography using the Cadiax Compact device (Gamma Dental, Klosterneuburg, Austria) and cephalometric analysis performed. Statistical analysis was performed using R statistical software.
RESULTS
There was no statistical evidence to state that the value of SCI angle is different in I compared to II Skeletal Class. There were no statistically significant differences when comparing the I vs. III and II vs. III Skeletal Class. The lowest mean SCI angle values were found in subjects with Skeletal Class III. There were statistically significant differences in left-sided TCI between Class I and II. There was a statistically significant linear relationship between ANB angle value and SCI value.
CONCLUSIONS
Due to the wide individual variation in SCI and TCI values, it is advisable to use individual measurable parameters of mandibular movements during prosthetic reconstructions. The statistically significant relationship between SCI and ANB angle can be used to individualize the articulating parameters, especially in significant skeletal disproportions.
PubMed: 35566792
DOI: 10.3390/jcm11092664 -
Annals of Anatomy = Anatomischer... Feb 2022Objective data mainly from the comparative anatomy of various organs related to human speech and language is considered to unearth clues about the mechanisms behind... (Review)
Review
Objective data mainly from the comparative anatomy of various organs related to human speech and language is considered to unearth clues about the mechanisms behind language development. The two organs of the larynx and hyoid bone are considered to have evolved towards suitable positions and forms in preparation for the occurrence of the large repertoire of vocalization necessary for human speech. However, some researchers have asserted that there is no significant difference of these organs between humans and non-human primates. Speech production is dependent on the voluntary control of the respiratory, laryngeal, and vocal tract musculature. Such control is fully present in humans but only partially so in non-human primates, which appear to be able to voluntarily control only supralaryngeal articulators. Both humans and non-human primates have direct cortical innervation of motor neurons controlling the supralaryngeal vocal tract but only human appear to have direct cortical innervation of motor neurons controlling the larynx. In this review, we investigate the comparative morphology and function of the wide range of components involved in vocal production, including the larynx, the hyoid bone, the tongue, and the vocal brain. We would like to emphasize the importance of the tongue in the primary development of human speech and language. It is now time to reconsider the possibility of the tongue playing a definitive role in the emergence of human speech.
Topics: Animals; Brain; Laryngeal Muscles; Larynx; Primates; Speech; Voice
PubMed: 35032565
DOI: 10.1016/j.aanat.2022.151887 -
The International Journal of... 2021To evaluate and compare the occlusal fit of zirconia crowns designed using a digital articulator method and the traditional method in a self-controlled clinical trial.
PURPOSE
To evaluate and compare the occlusal fit of zirconia crowns designed using a digital articulator method and the traditional method in a self-controlled clinical trial.
MATERIALS AND METHODS
Two zirconia crowns each were prepared for 12 patients with a single posterior tooth defect using two different methods: a digital articulator method and the traditional method. In the traditional method, casts were scanned using a model scanner, and the relative positions of the maxillary and mandibular arches were determined by the intercuspal occlusion of the casts. In the digital articulator method, casts were mounted on a mechanical articulator and scanned, and the relative positions were determined by their respective positions in the articulator. Additional dynamic occlusal adjustments of the digital articulator crowns were performed. Both groups of zirconia crowns were milled in a five-axis milling machine. The time required for occlusal adjustments, the occlusal contacts, the occlusal contact distributions, the number of occlusal contacts, the relative occlusal forces, and patient satisfaction (visual analog scale score) were evaluated. Wilcoxon test, McNemar test, and paired t test were used to compare the parameters between the two methods.
RESULTS
The occlusal adjustment times for the digital articulator and traditional method crowns were 327 ± 226 seconds and 395 ± 338 seconds, respectively (P > .05). There were no significant differences in occlusal contacts, occlusal contact distributions, number of occlusal contacts, relative occlusal forces, or VAS scores between the two methods (P > .05).
CONCLUSION
A digital articulator method for single-crown restoration was applied successfully. Crowns fabricated using a digital articulator or the traditional method can achieve acceptable occlusal fit for single-crown restorations.
Topics: Computer-Aided Design; Crowns; Dental Articulators; Dental Prosthesis Design; Humans; Zirconium
PubMed: 33570515
DOI: 10.11607/ijp.6570 -
Cureus Dec 2022Introduction The importance of disocclusion in maintaining the health of the stomatognathic system is well established. However, the quantification of the same is...
Introduction The importance of disocclusion in maintaining the health of the stomatognathic system is well established. However, the quantification of the same is limited. This study aimed to determine the amount of posterior teeth disocclusion in protrusive and laterotrusive movements to establish the desired disocclusion in occlusal treatments. Materials and methods Twenty dentate subjects with Angles Class I occlusion, 18-30 years, were included in the study. Direct and indirect techniques measured disocclusion at the mesiobuccal cusp tip of the mandibular first molar. In the direct technique, the protrusive and working and nonworking records were made intraorally at the edge-to-edge position of maxillary and mandibular central incisors and canines, respectively. For the indirect technique, putty indices were made on a semi-adjustable articulator at 2 millimeters (mm) eccentric movements and the disocclusion records were then made intraorally using indices at the predetermined excursions. The records were trimmed, and the disocclusion was measured using an optical microscope (ZEISS Axio Imager 2; Carl Zeiss Microscopy Deutschland GmbH, Oberkochen, Germany). The comparison of disocclusion by both techniques was done by paired t-test. The Pearson correlation coefficient was used to analyze the statistical correlation between the disocclusion obtained during different excursive movements. Results The mean disocclusion obtained by direct technique was 1.72 ± .49 mm in protrusion, 1.19 ± .50 mm for the working side, and 2.54 ± .70 mm for the nonworking side. For the indirect technique, the disocclusion obtained was 1.22 ± .37 mm in protrusion, 8.57 ± .33 mm for the working side, and 1.71 ± .61 mm for the nonworking side. On comparison, there was a statistically significant difference (<0.05) seen for the values between the groups for direct and indirect subgroups except for the left working subgroup (>0.05) with higher values in the direct group. Conclusions The disocclusion obtained by the direct technique was higher than that obtained by the indirect technique. For both techniques, as the working side disocclusion increased, the nonworking side disocclusion also increased.
PubMed: 36627993
DOI: 10.7759/cureus.32306 -
International Journal of Computerized... Feb 2023The aim of the present study was to present the different stages of prosthetic treatment planning involved in the design of an esthetic smile and the improvement of...
AIM
The aim of the present study was to present the different stages of prosthetic treatment planning involved in the design of an esthetic smile and the improvement of masticatory function using CAD/CAM technology.
MATERIALS AND METHODS
The patient underwent the following tests and procedures: CBCT (CS 9300; Carestream), intraoral scans and occlusal detection (CS 3600; Carestream), a photographic portrait session (Nikon D610; Nikon), a face scan (Bellus 3D FaceApp; iPhone XS, Apple), and registration of individual temporomandibular joint (TMJ) angles and mandibular movements with a Zebris for Ceramill device (Amman Girrbach). All the data were transferred to Ceramill Mind software (Amman Girrbach) where they were integrated. The face scan and photographs were superimposed on the CBCT scans. Scans of the dental arches were combined with the CBCT scans. On this CBCT base, the position of the condyles in the articular fossae was determined. A Virtual Artex CR virtual articulator (Amann Girrbach) was attached to the 3D object. Individual TMJ angles and mandibular movements were then introduced.
RESULTS
A virtual patient was created in the Ceramill Mind software. The optimal shape and position of each tooth were designed into the program. The wax-up was printed using a 3D printer and a temporary mock-up, and final restorations were made for the patient. At the same time, the esthetics of the smile was improved, and a harmonious central occlusion and articulation were obtained on virtual models and in the patient's oral cavity.
CONCLUSION
The presented digital planning protocol allows the working out of an optimal solution in complicated patient cases from both the functional and esthetic points of view. (Int J Comput Dent 2023;26(1):61-0; doi: 10.3290/j.ijcd.b2599445).
Topics: Humans; Esthetics, Dental; Software; Mouth; Tooth; Smiling; Computer-Aided Design
PubMed: 35072423
DOI: 10.3290/j.ijcd.b2599445 -
Journal of Prosthodontics : Official... Apr 2022To analyze the accuracy of transferring casts in maximal intercuspal position to a virtual articulator by using transfer plates in the laboratory scanner before and...
PURPOSE
To analyze the accuracy of transferring casts in maximal intercuspal position to a virtual articulator by using transfer plates in the laboratory scanner before and after occlusal optimization.
MATERIAL AND METHODS
Five sets of standard dental casts were mounted on a mechanical articulator in maximal intercuspal position. The number and position of occlusal contacts were determined with 12-μm articulating foil. After a calibration process according to the manufacturer's instructions, the mountings were transferred to a virtual articulator using the transfer plates in a laboratory scanner. The occlusion of the digital casts was determined before and after the occlusal optimization process. Then, the sensitivity and positive predictive value were determined by comparing the occlusal contact points in the virtual articulator with those in the mechanical articulator. To evaluate trueness, the occlusal surface of the maxillary teeth in the mechanical articulator was recorded by polyvinyl siloxane occlusal record in maximal intercuspal position and retained on the mandibular arch. The trueness was calculated as the deviation between the occlusal surface of the maxillary teeth in the mechanical articulator and the virtual articulator. To evaluate precision, one set of the casts was scanned 10 times. And the deviation of the interarch position of the maxillary arches when superimposing the mandibular arches of every 2 different scans was calculated.
RESULTS
The sensitivity before occlusal optimization (0.14 ± 0.15) was significantly lower than that after occlusal optimization (0.82 ± 0.10) (p = 0.003). However, there was no significant difference between the positive predictive value before (0.80 ± 0.45) and after (0.81 ± 0.09) occlusal optimization (p = 0.952). The trueness before (91.0 ± 10.7 µm) and after (75.4 ± 25.2 µm) occlusal optimization had no significant difference (p = 0.249). The precision before occlusal optimization (11.6 ± 3.8 µm) was significantly superior to that after occlusal optimization (75.6 ± 39.2 µm ) (p < 0.001).
CONCLUSIONS
The accuracy of transferring casts in maximal intercuspal position to a virtual articulator using transfer plates in the laboratory scanner could be improved after occlusal optimization and can meet the clinical needs for occlusal design and analysis of prostheses.
Topics: Dental Articulators; Dental Occlusion; Jaw Relation Record; Maxilla; Tooth
PubMed: 34196456
DOI: 10.1111/jopr.13405 -
The International Journal of... 2020To research and develop a novel virtual articulator system (the PN-300) based on computer binocular vision, raster scanning, and simulation technology and to conduct a...
PURPOSE
To research and develop a novel virtual articulator system (the PN-300) based on computer binocular vision, raster scanning, and simulation technology and to conduct a preliminary evaluation of its accuracy.
MATERIALS AND METHODS
Two digital cameras were used to build the trajectory-tracking part of the virtual articulator system, and cameras combined with a projection module were used to form the scanning part of the system. The most prominent feature of the PN-300 is its ability to simultaneously obtain the 3D data of the subject's teeth and the movement trajectory of the mandible relative to the maxilla. The PN-300 recorded the linear, circular, and rectangular quadrilateral movements of a high-accuracy 3D electronic translation stage. The accuracy of measurement of the inclination of incisal guidance derived from the PN-300 based on the PROTAR evo7 articulator was also estimated.
RESULTS
The measurement error was below 100 μm for the linear and circular movements, and the angle error was within 0.2 degrees for the rectangular quadrilateral movements. The error of inclination of protrusive incisal guidance was 1.51 ± 0.68 degrees, and for incisal guidance was 0.82 ± 0.55 degrees. Trajectories and incisal 3D data obtained by the PN-300 were combined with data from plaster models and CBCT to simulate mandibular movement and to calculate the trajectories of the condyle.
CONCLUSION
The PN-300 achieved a good accuracy for recording mandibular movement and can be expected to calculate the movement of the condyle.
Topics: Dental Articulators; Dentition; Mandible; Maxilla; Movement
PubMed: 32639704
DOI: 10.11607/ijp.6480 -
The Journal of Prosthetic Dentistry Nov 2023The introduction of digital technology in dentistry has resulted in a shift from conventional methods to digital techniques. However, mounting a digitized dental cast on...
STATEMENT OF PROBLEM
The introduction of digital technology in dentistry has resulted in a shift from conventional methods to digital techniques. However, mounting a digitized dental cast on a virtual articulator is challenging. Several techniques have been suggested to resolve this problem, but in the absence of a standardized method, digitized dental casts are often mounted arbitrarily on a virtual articulator.
PURPOSE
The purpose of this clinical study was to compare the accuracy of a novel virtual facebow transfer (VM) technique based on cone beam computed tomography (CBCT) with that of the conventional mounting (CM) technique using a facebow.
MATERIAL AND METHODS
Five repeated mountings were performed with each technique for 15 participants. In the CM group, dental casts were mounted using a facebow record and scanned for transmission to the virtual dental space. In the VM group, digital dental casts were mounted on the standard tessellation language file of a reference articulator by reconstructing a file of the participant's skull from CBCT data. In this group, a virtual facebow, prepared by scanning the articulator and facebow complex, was used. After the CM and VM casts had been aligned, the coordinates of target points set on the maxillary right central incisor, maxillary right first molar, and maxillary left first molar were determined, and the mean ±standard deviation distance between the target points was calculated to compare the precision of the techniques. Additionally, vectors of the target point on the maxillary right central incisor were compared to analyze the spatial difference between the techniques. Finally, the occlusal plane angle was calculated. For the correlation analysis of repeated measured data, a 1-way repeated measures analysis of variance (ANOVA) was first performed. The Kolmogorov-Smirnov test was performed to determine normality, and a paired t test and the Wilcoxon signed rank test were performed for normally and nonnormally distributed variables, respectively (α=.05).
RESULTS
The mean distance between target points was significantly greater in the CM group (4.72 ±1.45 to 5.17 ±1.54 mm) than in the VM group (2.14 ±0.58 to 2.35 ±0.60 mm) (P<.05). The standard deviation between target points was significantly greater in the CM group (1.60 ±0.64 to 2.30 ±0.87 mm) than in the VM group (0.74 ±0.23 to 1.12 ±0.45 mm) (P<.05). The maxillary right central incisor was located more anteriorly in the VM group than in the CM (100%, P<.05) group. The occlusal plane angle was significantly steeper in the CM group than in the VM group (8.14 degrees versus 2.13 degrees, P<.05).
CONCLUSIONS
The VM technique was more precise than the CM technique. VM casts were positioned ahead of CM casts. Further, the occlusal plane angle tended to be steeper with the CM technique than with the VM technique.
PubMed: 37957064
DOI: 10.1016/j.prosdent.2023.08.025