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The Journal of Prosthetic Dentistry Jul 2023This technique report describes a fully digital workflow to create a prosthetic articulator-based implant rehabilitation (PAIR) virtual patient for complete-arch or...
This technique report describes a fully digital workflow to create a prosthetic articulator-based implant rehabilitation (PAIR) virtual patient for complete-arch or complete-mouth implant rehabilitation. This workflow uses a custom gothic arch tracer during the cone beam computed tomography (CBCT) scan and a 3-dimensional virtual facebow when superimposing data. The PAIR virtual patient possesses reliable centric relation and vertical dimension of occlusion and is compatible with virtual articulators. Computer-aided implant planning and a digital prosthetic design can be seamlessly integrated by using this virtual patient.
Topics: Humans; Dental Implants; Dental Articulators; Computer-Aided Design; Image Processing, Computer-Assisted; Cone-Beam Computed Tomography; Imaging, Three-Dimensional
PubMed: 34756772
DOI: 10.1016/j.prosdent.2021.09.013 -
BMC Oral Health Nov 2021The scanning of plaster models for three-dimensional (3D) construction requires their rigid fixation in the intercuspal position. Factors such as installation, motion,...
PURPOSE
The scanning of plaster models for three-dimensional (3D) construction requires their rigid fixation in the intercuspal position. Factors such as installation, motion, and scanning procedures influenced the accuracy of this method, which ultimately influence the results. Therefore, the present study attempted to provide an optimal and accurate method with less complex procedures and a more accessible equipment for determining the intercuspal relation in the 3D occlusal construction of dental models.
METHODS
A pair of plastic mounting plates that could be directly attached to a mechanical articulator was designed and 3D printed. Nine axial hemispherical concaves were introduced on the axial surface of each plate. The rigidly fixed maxillary and mandibular dental models were scanned directly. The distances D between nine pairs of concaves on both mounting plates adhered to the maxillary and mandibular sections of the articulator were measured using the three-coordinate measuring machine Faro Edge as the reference. The present study comprised seven test groups varying in number and location. Assessing the reference points from each of the seven groups performed the 3D construction. The Geomagic Studio software was used to construct the concaves of digital casts, and the distances D between the pairs of concaves were measured as test values. Variable differences between D and D were analyzed.
RESULTS
An optimum distribution scheme was obtained for reference point registration by quantitatively evaluating accuracy levels of the 3D constructions of different reference point distribution patterns. This scheme can serve as a reference for related studies and dental clinic operations.
CONCLUSIONS
Three-dimensional construction of the intercuspal relation during scanning of the maxillary and mandibular models with an accuracy of 0.046 mm ± 0.009 mm can be achieved using the improved design of mounting plates.
Topics: Dental Articulators; Humans; Imaging, Three-Dimensional; Mandible; Models, Dental; Software
PubMed: 34732188
DOI: 10.1186/s12903-021-01919-z -
Journal of Pharmacy & Bioallied Sciences Jun 2021Various clinical methods for recording the condylar guidance (CG) are the intraoral check bite method, graphic tracings, and functional recordings. Accuracy of graphic...
BACKGROUND
Various clinical methods for recording the condylar guidance (CG) are the intraoral check bite method, graphic tracings, and functional recordings. Accuracy of graphic tracings is affected by patient-related factors such as neuromuscular control of the individual, stability of record bases as well as stability of recording media. The current recommended average settings using Hanau's formula questionable, and thus reassessment is needed.
PURPOSE
The purpose of this study is to use radiographic technique to determine the lateral CG and compare these values with those obtained using Hanau's formula and to evaluate whether there are differences between the right and left paths of the condyles.
MATERIALS AND METHODS
Twenty completely edentulous patients were selected. Articulator was modified with sectioned protractor for obtaining per degree interval calibration. With the protrusive records, the horizontal CG (H) was adjusted and the Bennett's angle (LCG-C) was calculated using the formula. With the tracing device in the mouth, sub-mento vertex projection radiographs were obtained. Each radiograph was traced and superimposed for Bennett angle determination (LCG-M).
RESULTS
The median (interquartile range [IQR]) of right and left LCG-C were 15.45 (0.8) and 15.50 (0.7), respectively. The median (IQR) of right and left LCG-M were 37.00 (6.0) and 36.50 (6.8), respectively. A statistically significant difference exists between LCG-C and LCG-M. Both LCG-C and-M values exhibited no variations on both sides.
CONCLUSIONS
Radiographic technique yielded an amplified LCG when compared to the value obtained by Hanau's formula.
PubMed: 34447149
DOI: 10.4103/jpbs.JPBS_640_20 -
Journal of Indian Prosthodontic Society 2021This study aimed to evaluate the combined influence of condylar and incisal guidance in canine-guided and group function occlusal schemes.
AIMS
This study aimed to evaluate the combined influence of condylar and incisal guidance in canine-guided and group function occlusal schemes.
SETTINGS AND DESIGN
In vivo - Cross sectional study.
MATERIALS AND METHODS
A total number of 88 subjects were selected and classified into two groups: 44 subjects with canine guided and 44 subjects with group function occlusal schemes. Condylar and incisal guidance tracings of both the groups were recorded using SAM AXIOQUICK RECORDER (School Articulator Munich) and evaluated.
STATISTICAL ANALYSIS USED
Kolmogorov-Smirnov test and Shapiro-Wilk test were employed to test the normality of data. Independent sample t-test and Mann-Whitney U-test was performed for quantitative variables.
RESULTS
The condylar and incisal guidance among canine-guided individuals was 31.38 ± 12.01 and 55.83 ± 14.04, respectively, while in group function individuals, it was 29.44 ± 12.65 and 43.74 ± 20.27.
CONCLUSIONS
Within the limitations of the present study, condylar guidance was similar in subjects with both schemes of occlusion, whereas steeper incisal guidance was noticed in canine-guided individuals as compared to group function.
Topics: Animals; Cross-Sectional Studies; Dogs; Humans; Mandibular Condyle; Statistics, Nonparametric
PubMed: 34380812
DOI: 10.4103/jips.jips_183_21 -
Revista Cientifica Odontologica... 2021To compare the angle of the sagittal condylar guidance obtained from the radiographic and clinical records of dentate patients.
OBJECTIVE
To compare the angle of the sagittal condylar guidance obtained from the radiographic and clinical records of dentate patients.
MATERIALS AND METHODS
The sample consisted of 32 patients in whom strict lateral radiography and positional records were performed: in centric relation, protrusive recording 5 mm in right laterality and protrusive recording 5 mm in left laterality. With the positional registration of the facebow, the upper model was articulated, while the lower model was articulated with the positional registration in centric relation, and with the protrusive lateral registrations on the right and left side the condylar guidance was obtained for programming the semi-adjustable articulator. Statistics were performed with the SPSS program version 24 in Spanish. Normality was evaluated using the Shapiro-Wilk test, for data with normal distribution, and the Student's T test and Pearson's correlation were performed in descriptive statistics.
RESULTS
The statistical analyses showed that gender and age influence the angle measurement of the sagittal condylar guide. The radiographic method presented a condylar guide angle of 35.69 ± 5.18, being 35.69 ± 5.16 with the clinical method (p> 0.05). Pearson's correlation test showed an important correlation between the two methods (r = 0.948, p <0.001).
CONCLUSIONS
There is a high correlation in the measurements obtained from the angle of the sagittal condylar guide and the radiographic and clinical records, indicating that both methods are effective.
PubMed: 38465274
DOI: 10.21142/2523-2754-0902-2021-060 -
Materials (Basel, Switzerland) May 2021The purpose of this in vitro study was to compare the accuracy of the proximal and occlusal contacts of single implant crowns fabricated with four data capture methods....
The purpose of this in vitro study was to compare the accuracy of the proximal and occlusal contacts of single implant crowns fabricated with four data capture methods. The resin models were mounted on an articulator, digitized using a laboratory scanner, and saved as a standard tessellation language (STL) file to serve as the master reference model (MRM). Two different intraoral scan body (ISB) systems were evaluated: polyetheretherketone (PEEK) short scan body (SSB) and PEEK long scan body (LSB) ( = 12). The digital impressions (SSB and LSB) were acquired using an intraoral scanner with ISB. Two different conventional techniques were also evaluated: PEEK short scan body with coping plastic cap (CPC) and pick-up coping (PUC) ( = 12). The implant impressions (CPC and PUC) were recorded using a conventional impression technique. The crown and abutment were fabricated with a milling machine and then placed on the resin model and scanned using a laboratory scanner. The scanned files were saved as STL files to serve as test datasets. The MRM and test datasets were superimposed, and the mesial, distal, and occlusal distances were calculated using a 3D inspection software and statistically analyzed using the Kruskal-Wallis H test (α = 0.05). The direct data capture group had more accurate contact points on the three surfaces, with mesial contact of 64.7 (12.8) µm followed by distal contact of 65.4 (15) µm and occlusal contact of 147 (35.8) µm in the SSB group, and mesial contact of 84.9 (22.6) µm followed by distal contact of 69.5 (19.2) µm and occlusal contact of 115.9 (27.7) µm in the LSB group ( < 0.001). The direct data capture groups are closer to the ideal proximal and occlusal contacts for single implant crowns than the indirect data capture groups. There was no difference in the accuracy between the two types of scan body (SSB and LSB).
PubMed: 34073329
DOI: 10.3390/ma14112843 -
Journal of International Society of... 2021To meet the needs of society, it is obligatory to provide standardized skill training to undergraduate students in dental colleges. Surveys related to teaching...
OBJECTIVES
To meet the needs of society, it is obligatory to provide standardized skill training to undergraduate students in dental colleges. Surveys related to teaching curriculum are valuable means to evaluate education across the country. The aim of this study was to find the trends in the undergraduate teaching curriculum, by determining the differences in the teaching methods and principles of fabrication of removable partial dentures in dental colleges in Saudi Arabia and to compare these with the curriculum of North American dental schools and Turkish dental schools.
MATERIALS AND METHODS
An online survey was conducted in 23 dental colleges of Saudi Arabia. Descriptive data analysis was performed to synopsize the information.
RESULTS
Eighteen out of 23 (78.23%) dental colleges of Saudi Arabia answered the questionnaire; 88.9% of the colleges follow the practice of using custom trays for making final impressions; and 44.4% of the colleges use only polyvinyl siloxane for making final impressions. Semiadjustable articulators were commonly used for mounting study casts (61.1%) and master casts (66.6%). An in-house production laboratory is present in 72.2% of the colleges. Cobalt-chromium alloy is used in 94.4% of the colleges for the framework. A set protocol for postinsertion adjustment visits is followed in 94.4% of the colleges.
CONCLUSIONS
Dental colleges of Saudi Arabia have similar standards of removable partial denture education at the undergraduate level, with variations in a few aspects. Removable partial denture teaching programs of Saudi Arabian dental colleges are comparable to similar programs in dental schools of the United States and Turkey.
PubMed: 34036075
DOI: 10.4103/jispcd.JISPCD_374_20 -
Proceedings of the National Academy of... May 2021While there is increasing acceptance that even young infants detect correspondences between heard and seen speech, the common view is that oral-motor movements related...
While there is increasing acceptance that even young infants detect correspondences between heard and seen speech, the common view is that oral-motor movements related to speech production cannot influence speech perception until infants begin to babble or speak. We investigated the extent of multimodal speech influences on auditory speech perception in prebabbling infants who have limited speech-like oral-motor repertoires. We used event-related potentials (ERPs) to examine how sensorimotor influences to the infant's own articulatory movements impact auditory speech perception in 3-mo-old infants. In experiment 1, there were ERP discriminative responses to phonetic category changes across two phonetic contrasts (bilabial-dental /ba/-/ɗa/; dental-retroflex /ɗa/-/ɖa/) in a mismatch paradigm, indicating that infants auditorily discriminated both contrasts. In experiment 2, inhibiting infants' own tongue-tip movements had a disruptive influence on the early ERP discriminative response to the /ɗa/-/ɖa/ contrast only. The same articulatory inhibition had contrasting effects on the perception of the /ba/-/ɗa/ contrast, which requires different articulators (the lips vs. the tongue) during production, and the /ɗa/-/ɖa/ contrast, whereby both phones require tongue-tip movement as a place of articulation. This articulatory distinction between the two contrasts plausibly accounts for the distinct influence of tongue-tip suppression on the neural responses to phonetic category change perception in definitively prebabbling, 3-mo-old, infants. The results showing a specificity in the relation between oral-motor inhibition and phonetic speech discrimination suggest a surprisingly early mapping between auditory and motor speech representation already in prebabbling infants.
Topics: Acoustic Stimulation; Electroencephalography; Evoked Potentials; Female; Hearing; Humans; Infant; Language Development; Male; Pattern Recognition, Visual; Phonetics; Speech; Speech Perception; Tongue
PubMed: 33980713
DOI: 10.1073/pnas.2025043118 -
Journal of Prosthodontics : Official... Jan 2022To investigate the trueness and precision of virtual facebow records using a smartphone as a three-dimensional (3D) face scanner.
PURPOSE
To investigate the trueness and precision of virtual facebow records using a smartphone as a three-dimensional (3D) face scanner.
MATERIAL AND METHODS
Twenty repeated virtual facebow records were performed on two subjects using a smartphone as a 3D face scanner. For each subject, a virtual facebow was attached to his/her maxillary arch, and face scans were performed using a smartphone with a 3D scan application. The subject's maxillary arch intraoral scan was aligned to the face scan by the virtual facebow fork. This procedure was repeated 10 times for each subject. To investigate if the maxillary scan is located at the right position to the face, these virtual facebow records were superimposed to a cone-beam computed tomography (CBCT) head scan from the same subject by matching the face scan to the 3D face reconstruction from CBCT images. The location of maxillary arch in virtual facebow records was compared with its position in CBCT. The "trueness" of the proposed procedure is defined as the deviation between maxilla arch position in virtual facebow records and the CBCT images. The "precision" is defined as the deviation between each virtual facebow record. The linear deviation at left central incisor (#9), left first molar (#14), and right first molar (#3), as well as angular deviation of occlusal plane were analyzed with descriptive statistics. Differences between two objects were also explored with Mann Whitney U test.
RESULTS
The 20 virtual facebow records using the smartphone 3D scanner deviated from the CBCT measurements (trueness) by 1.14 ± 0.40 mm at #9, 1.20 ± 0.50 mm at #14, 1.12 ± 0.51 mm at the #3, and 1.48 ± 0.56° in the occlusal plane. The VFTs deviated from each other by 1.06 ± 0.50 mm at #9, 1.09 ± 0.49 mm at #14, 1.11 ± 0.58 mm at #3, and 0.81 ± 0.58° in the occlusal plane. When all sites combined, the trueness was 1.14 ± 0.40 mm, and the precision was 1.08 ± 0.52 mm. Out of eight measurements, three measurements were significantly different between subjects. Nevertheless, the mean difference was small.
CONCLUSIONS
Virtual facebow records made using smartphone-based face scan can capture the maxilla position with high trueness and precision. The deviation can be anticipated as around 1 mm in linear distance and 1° in angulation.
Topics: Computer-Aided Design; Cone-Beam Computed Tomography; Dental Occlusion; Female; Humans; Imaging, Three-Dimensional; Male; Maxilla; Models, Dental; Smartphone
PubMed: 33876857
DOI: 10.1111/jopr.13366 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Dec 2020To establish the workflow of determining the jaw position of repositioning splint with the aid of digital technique, and to evaluate the accuracy of this workflow and...
OBJECTIVE
To establish the workflow of determining the jaw position of repositioning splint with the aid of digital technique, and to evaluate the accuracy of this workflow and compare the accuracy of raising different vertical dimensions .
METHODS
A volunteer was recruited. The data of full-arch scans, cone beam computed tomography (CBCT) image and ultrasonic jaw motion tracking of the volunteer were acquired. The full-arch scans were merged with the CBCT image, which were then matched to the jaw motion tracking reference system. The jaw position of repositioning splint was determined when the anterior teeth opening was 3 mm and the condyle was in centric relation of the fossa in the sagittal plane. A digital repositioning splint was designed in the software based on virtual articulator and fabricated with additive manufacturing technique. After the splint was tried in, another CBCT image was taken and a qualitative analysis was conducted to compare the position of condyle between these two CBCT images. In the study, standard dental plaster casts with resin ball markers attached to the base were mounted onto a fully adjustable articulator in the intercuspal position. The dental casts were scanned by an extraoral scanner to establish digital models. The ultrasonic jaw motion tracking device was used to obtain simulated jaw movements on the articulator, which was repeated for three times. The digital models and data of jaw movements were merged in one coordination with the aid of bite forks. The jaw position of repositioning splint was determined by adjusting data of jaw movements, each of which was used to determine three vertical jaw positions 4 mm, 5 mm, and 6 mm with the horizontal jaw position of protrusion 2 mm. The virtual articulators with differently adjusted jaw movements were applied in designing repositioning splints, and the final repositioning splints and virtual jaw relationships were exported in STL format. Then the repositioning splints were fabricated with additive manufacturing technique and tried in plaster casts on the mechanical articulator, which were scanned and the jaw relationships on the mechanical articulator were exported later. The virtual jaw relationships and scanned jaw relationships were registered according to lower models and displacement of upper models was calculated. Ball markers were fit to acquire the coordinates of centers and absolute difference values of centers along three coordinating axes , , and were calculated. One-way analysis of variance was conducted using SPSS 18.0 software to compare deviations of the three different vertical jaw relationships in two-side test and the significance level was 0.05.
RESULTS
With the aid of multi-source data fusion and individualized jaw motion, the clinical workflow of determining jaw position of repositioning splint was preliminarily established. The designed jaw position was realized on the right and the condyle was more inferior than the designed position on the left. Both displacement of the upper models and absolute difference values of centers showed no significant differences (>0.05) in different vertical jaw dimensions. The displacement of the upper models was (0.25±0.04) mm. The absolute difference values of centers along the three coordinating axes , , and were respectively (0.08±0.01) mm, (0.30±0.02) mm, and (0.21±0.04) mm.
CONCLUSION
A novel method of determining the jaw position of repositioning splint with the aid of digital technique is established. It is proved to be feasible by try-in after multi-data fusion, computer-aided design and computer-aided manufacturing. As is shown , it is accurate to apply this method in adjusting jaw position. Further clinical trial will be designed to evaluate its clinical effect.
Topics: Computer-Aided Design; Cone-Beam Computed Tomography; Dental Articulators; Humans; Jaw Relation Record; Occlusal Splints; Software; Splints
PubMed: 33550339
DOI: 10.19723/j.issn.1671-167X.2021.01.012