Accuracy of the maxillary cast transfer into the virtual semi-adjustable articulator by using analog and digital facebow record methods

STATEMENT OF PROBLEM

Different digital methods have been described for transferring the maxillary cast into a virtual articulator; however, its accuracy remains uncertain.

PURPOSE

The purpose of this in vitro study was to compare the accuracy of the maxillary cast transfer into the virtual semi-adjustable articulator by using analog and digital methods.

MATERIAL AND METHODS

A maxillary typodont with 5 markers was positioned into a mannequin, which was digitized by using an industrial scanner (ATOS Q) and an extraoral scan of the typodont obtained (T710). Three groups were created based on the technique used to transfer the maxillary cast into the virtual articulator (Panadent PCH Articulator): conventional facebow record (CNV group), digital photograph (P group), and facial scanning (FS group) (n=10). In the CNV group, conventional facebow records (Kois Dentofacial analyzer system) were digitized (T710) and used to mount the maxillary scan into the articulator by aligning it with the reference platform (Kois adjustable platform) (DentalCAD). In the P group, photographs with the reference glasses (Kois Reference Glasses 3.0) were positioned in the mannequin. Each photograph was superimposed with the maxillary scan. Then, the maxillary scan was transferred into the virtual articulator by using the true horizontal plane information of the photograph. In the FS group, facial scans with an extraoral scan body (Kois Scan Body) were positioned in the mannequin by using a facial scanner (Instarisa). The extraoral scan body was digitized by using the same extraoral scanner. The digitized extraoral scan body provided the true horizontal plane information that was used to mount the maxillary scan into the articulator, along with the Kois disposable tray of the scan body. On the reference scan and each specimen, 15 linear measurements between the markers of the maxillary scans and the horizontal plane of the virtual articulator and 3 linear measurements between the maxillary dental midline and articulator midline were calculated. The measurements of the reference scan were used as a control to assess trueness and precision. Trueness was analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey tests (α=.05). Precision was evaluated by using the Levene and pairwise comparisons Wilcoxon Rank sum tests.

RESULTS

No significant trueness (P=.996) or precision (P=.430) midline discrepancies were found. Significant posterior right (P<.001), anterior (P=.005), posterior left (P<.001), and overall (P<.001) trueness discrepancies were revealed among the groups. The P group obtained the best posterior right, posterior left, and overall trueness and precision. The P and FS groups demonstrated the best anterior trueness, but no anterior precision discrepancies were found.

CONCLUSIONS

The techniques tested affected the accuracy of the maxillary cast transfer into the virtual semi-adjustable articulator. In the majority of the parameters assessed, the photography method tested showed the best trueness and precision values. However, the maxillary cast transfer accuracy ranged from 137 ±44 µm to 453 ±176 µm among the techniques tested.

Accuracy comparison of the maxillary cast transfer into the virtual semi-adjustable articulator between an analog facebow record and a digital photography technique

STATEMENT OF PROBLEM

Digital photographs can be used for transferring the maxillary cast into the virtual semi-adjustable articulator; however, its accuracy remains unknown.

PURPOSE

The purpose of the present study was to compare the accuracy of the maxillary cast transfer into the virtual semi-adjustable articulator by using an analog and a digital standardized photography technique.

MATERIAL AND METHODS

A maxillary cast was digitized (T710) and positioned into a dental mannequin. The dental midline was not coincident with the facial midline and the maxillary occlusal plane was tilted. A reference scan of the assembled mannequin was obtained by using a facial scanner (Instarisa). Two groups were created based on the technique used to transfer the maxillary cast into the articulator (Panadent PCH): conventional facebow record (CNV group) or digital photograph (Photo group) (n=10). In the CNV group, facebow records (Kois Dentofacial analyzer system) were digitized (T710) and used to transfer the maxillary scan into the articulator by aligning it with the reference platform (Kois adjustable platform). In the Photo group, photographs with a reference glasses (Kois Reference Glasses) positioned into the mannequin were acquired. Each photograph was aligned with the maxillary scan. Then, the maxillary scan was transferred into the articulator by using the true horizontal axis information contained in the photograph. On the reference scan and each specimen, 10 linear measurements between the buccal cusps of the maxillary scan and the horizontal plane of the virtual articulator and a linear measurement between the maxillary dental midline and articulator midline were calculated. The measurements of the reference scan were used as a control to compute trueness and precision. Trueness was analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey test (α=.05). Precision was evaluated by using the Levene and Wilcoxon Rank sum tests (α=.05).

RESULTS

The overall discrepancy measured in the CNV group was 0.620 ±0.396 mm, while in the Photo group it was 1.282 ±0.118 mm. Significant trueness differences were found in the midline (P=.037), anterior (P=.050), posterior right (P<.001), posterior left (P=.012), and overall discrepancy (P<.001) between the CNV and Photo groups. Significant precision discrepancies were found in the midline (P=.012), posterior right (P<.001), anterior (P<.001), posterior left (P=.002), and overall discrepancy (P<.001) between the CNV and Photo groups.

CONCLUSIONS

The facebow record method impacted the accuracy of the maxillary cast transfer. The Photo group obtained better trueness in the midline transfer than the CNV group; however, the CNV group demonstrated better trueness in the anterior, posterior right, posterior left, and overall discrepancy of the maxillary cast transfer compared with the Photo group. Overall, the Photo group obtained better precision than the CNV group.

Utilizing additively manufactured custom devices to record mandibular motion by using optical jaw tracking systems: A dental technique

A technique is described for fabricating additively manufactured custom holder devices to assist optical jaw tracking systems. Most jaw tracking systems provide standardized holders attached to the trackers. The technique described aims to provide a more efficient custom holder design that improves marker retention and mandibular motion recording, decreases the incidence of the procedure complications such as tracker decementation or displacement, and increases the efficiency of the intervention by reducing the positioning time of the trackers in the patient's mouth during the clinical appointment.

Digital workflow to measure the mandibular range of motion using different jaw tracking technologies

The analysis of the mandibular range of motion (ROM) includes the evaluation of maximum opening, deviation upon opening, and amplitude of the left and right excursive movements and protrusion. Conventionally, ROM assessment has been directly measured in the patient's mouth by using a ROM ruler. The development of jaw tracking systems, such as magnetometry and photometric devices, allows the digital assessment of the mandibular ROM. The present manuscript describes the clinical protocols for recording and measuring the mandibular ROM by using different jaw tracking systems.

Digital diagnostic occlusal equilibration combining an intraoral scanner, optical jaw tracking system, and dental design program: A dental technique

Patients with aberrant occlusal patterns, including constricted mastication patterns or occlusal dysfunction, may require occlusal equilibration. Conventional diagnostic procedures involve diagnostic stone casts mounted in the articulator. During diagnostic procedures, occlusal equilibration methods are simulated on mounted stone casts to analyze the amount of dental structure that may need to be removed. A technique to virtually simulate an occlusal equilibration procedure is described. Digital data acquisition procedures include diagnostic casts acquired using an intraoral scanner and the repeatable reference position of the mandible or centric relation, excursive movements, and the mastication pattern captured using an optical jaw tracking system. The jaw tracker and dental design programs are used to simulate the occlusal equilibration.

Implementing an optical jaw tracking system to locate centric occlusion: A dental technique

Optical jaw tracking systems are designed to record the static maxillomandibular relationship and the mandibular motion of a patient, including excursive movements and mastication pattern. This digital data acquisition technology can be integrated into diagnostic and treatment planning procedures, as well as into designing dental prostheses. A step-by-step protocol to record a patient's digital data, including the repeatable reference position of the jaw or centric relation, by using an intraoral scanner, Kois deprogrammer, and optical jaw tracking system is described. The data are then processed in the software program of the jaw tracking system to locate centric occlusion.

Using an additively manufactured natural head position reference device to transfer the horizon orientation plane and integrate it with a 3-dimensional virtual patient: A dental technique

A virtual patient is obtained by aligning a patient's digital information, including facial and intraoral digital scans with or without hard tissue information from a cone beam computed tomography scan. However, while computer-aided design programs facilitate virtual patient integration, they do not provide a way to relate the horizon orientation with the patient's horizontal and vertical facial references. The present technique describes a way of relating the horizon orientation plane to the natural head position of the patient. An additively manufactured natural head position reference device was used to transfer the horizon orientation plane to the 3-dimensional virtual patient.

Discrepancies in the occlusal devices designed by an experienced dental laboratory technician and by 2 artificial intelligence-based automatic programs

STATEMENT OF PROBLEM

Artificial intelligence (AI) models have been developed for different applications, including the automatic design of occlusal devices; however, the design discrepancies of an experienced dental laboratory technician and these AI automatic programs remain unknown.

PURPOSE

The purpose of this in vitro study was to compare the overall, intaglio, and occlusal surface discrepancies of the occlusal device designs completed by an experienced dental laboratory technician and two AI automatic design programs.

MATERIAL AND METHODS

Virtually articulated maxillary and mandibular diagnostic casts were obtained in a standard tessellation language (STL) file format. Three groups were created depending on the operator or program used to design the occlusal devices: an experienced dental laboratory technician (control group) and two AI programs, namely Medit Splints from Medit (Medit group) and Automate from 3Shape A/S (3Shape group) (n=10). To minimize the discrepancies in the parameter designs among the groups tested, the same printing material and design parameters were selected. In the control group, the dental laboratory technician imported the articulated scans into a dental design program (DentalCAD) and designed a maxillary occlusal device. The occlusal device designs were exported in STL format. In the Medit and 3Shape groups, the diagnostic casts were imported into the respective AI programs. The AI programs automatically designed the occlusal device without any further operator intervention. The occlusal device designs were exported in STL format. Among the 10 occlusal designs of the control group, a random design (shuffle deck of cards) was used as a reference file to calculate the overall, intaglio, and occlusal discrepancies in the specimens of the AI groups by using a program (Medit Design). The root mean square (RMS) error was calculated. Kruskal-Wallis, and post hoc Dwass-Steel-Critchlow-Fligner pairwise comparison tests were used to analyze the trueness of the data. The Levene test was used to assess the precision data (α=.05).

RESULTS

Significant overall (P<.001), intaglio (P<.001), and occlusal RMS median value (P<.001) discrepancies were found among the groups. Significant overall RMS median discrepancies were observed between the control and the Medit groups (P<.001) and the control and 3Shape groups (P<.001). Additionally, significant intaglio RMS median discrepancies were found between the control and the Medit groups (P<.001), the Medit and 3Shape groups (P<.001), and the control and 3Shape groups (P=.008). Lastly, significant occlusal RMS median discrepancies were found between the control and the 3Shape groups (P<.001) and the Medit and 3Shape groups (P<.001). The AI-based software programs tested were able to automatically design occlusal devices with less than a 100-µm trueness discrepancy compared with the dental laboratory technician. The Levene test revealed significant overall (P<.001), intaglio (P<.001), and occlusal (P<.001) precision among the groups tested.

CONCLUSIONS

The use of a dental laboratory technique influenced the overall, intaglio, and occlusal trueness of the occlusal device designs obtained. No differences were observed in the precision of occlusal device designs acquired among the groups tested.

Maxillary occlusal device designed with an anterior platform for guiding the occlusal adjustments during the delivery appointment: A dental protocol

OBJECTIVE

To describe a technique for fabricating an additively manufactured maxillary occlusal device using a complete digital workflow.

CLINICAL CONSIDERATIONS

The maxillary occlusal device design may include an anterior platform to guide the positioning of the mandible in a reproducible position for facilitating the delivery procedure.

CONCLUSIONS

The described technique provides a more efficient and less time-consuming method for designing an manufacturing a printed occlusal device, when compared with conventional fabrication techniques.

CLINICAL SIGNIFICANCE

The additively manufactured occlusal device designed with an anterior platform guides the positioning of the mandible in a reproducible position, facilitates the delivery procedures, and produces a more efficient and less time-consuming method when compared with conventional methods.

An overview of the digital occlusion technologies: Intraoral scanners, jaw tracking systems, and computerized occlusal analysis devices

OBJECTIVES

Within the development of digital technologies, dental professionals aim to integrate virtual diagnostic articulated casts obtained by using intraoral scanners (IOSs), the mandibular motion of the patient recorded by using an optical jaw tracking system, and the information provided by computerized occlusal analysis systems. This article describes the various digital technologies available for obtaining the digital occlusion of a patient and outlines its challenges and limitations.

OVERVIEW

The factors that influence the accuracy of the maxillomandibular relationship of diagnostic casts obtained by using IOSs are reviewed, as well as the occurrence of occlusal collisions or mesh interpenetrations. Different jaw tracking systems with varying digital technologies including ultrasonic systems, photometric devices, and artificial intelligence algorithms are reviewed. Computerized occlusal analysis systems for detecting occlusal contacts in a time sequential manner with the pressure distribution on the occlusal surfaces are reviewed.

CONCLUSIONS

Digital technologies provide powerful diagnostic and design tools for prosthodontic care. However, the accuracy of these digital technologies for acquiring and analyzing the static and dynamic occlusion need to be further analyzed.

CLINICAL SIGNIFICANCE

Efficiently implementing digital technologies into dental practice requires an understanding of the limitations and state of current development of the digital acquisition methods for digitizing the static and dynamic occlusion of a patient by using IOSs, digital jaw trackers, and computerized occlusal analysis devices.

Scanning accuracy and scanning area discrepancies of intraoral digital scans acquired at varying scanning distances and angulations among 4 different intraoral scanners

STATEMENT OF PROBLEM

The accuracy of intraoral scanners (IOSs) can be affected by operator handling; however, the scanning area and accuracy discrepancies acquired at different scanning distances and angulations among IOSs remain uncertain.

PURPOSE

The objective of this in vitro study was to compare the scanning area and scanning accuracy of the intraoral digital scans obtained at 3 scanning distances with 4 different scanning angulations among 4 different IOSs.

MATERIAL AND METHODS

A reference device (reference file) was designed with 4 inclinations (0, 15, 30, and 45 degrees) and printed. Four groups were created based on the IOS: i700, TRIOS4, CS 3800, and iTero scanners. Four subgroups were generated depending on the scanning angulation (0, 15, 30, and 45 degrees). Each subgroup was divided into 3 subgroups based on the scanning distance: 0, 2, and 4 mm (N=720, n=15). The reference devices were positioned in a z-axis calibrated platform for standardizing the scanning distance. In the i700-0-0 subgroup, the 0-degree reference device was positioned in the calibrated platform. The wand of the IOS was positioned in a supporting framework with a 0-mm scanning distance, and the scans were acquired. In the i700-0-2 subgroup, the platform was lowered for a 2-mm scanning distance followed by the specimen acquisition. In the i700-0-4 subgroup, the platform was further lowered for a 4-mm scanning distance, and the scans were obtained. For the i700-15, i700-30, and i700-45 subgroups, the same procedures were carried out as in the i700-0 subgroups respectively, but with the 10-, 15-, 30-, or 45-degree reference device. Similarly, the same procedures were completed for all the groups with the corresponding IOS. The area of each scan was measured. The reference file was used to measure the discrepancy with the experimental scans by using the root mean square (RMS) error. Three-way ANOVA and post hoc Tukey pairwise comparison tests were used to analyze the scanning area data. Kruskal-Wallis and multiple pairwise comparison tests were used to analyze the RMS data (α=.05).

RESULTS

IOS (P<.001), scanning distance (P<.001), and scanning angle (P<.001) were significant factors of the scanning area measured among the subgroups tested. A significant group×subgroup interaction was found (P<.001). The iTero and the TRIOS4 groups obtained higher scanning area mean values than the i700 and CS 3800 groups. The CS 3800 obtained the lowest scanning area among the IOS groups tested. The 0-mm subgroups obtained a significantly lower scanning area than the 2- and 4-mm subgroups (P<.001). The 0- and 30-degree subgroups obtained a significantly lower scanning area than the 15- and 45-degree subgroups (P<.001). The Kruskal-Wallis test revealed significant median RMS discrepancies (P<.001). All the IOS groups were significantly different from each other (P<.001), except for the CS 3800 and TRIOS4 groups (P>.999). All the scanning distance groups were different from each other (P<.001).

CONCLUSIONS

Scanning area and scanning accuracy were influenced by the IOS, scanning distance, and scanning angle selected to acquire the digital scans.

Differences in maxillomandibular relationship recorded at centric relation when using a conventional method, four intraoral scanners, and a jaw tracking system: A clinical study

STATEMENT OF PROBLEM

Digital systems including intraoral scanners (IOSs) and optical jaw tracking systems can be used to acquire the maxillomandibular relationship at the centric relation (CR). However, the discrepancy of the maxillomandibular relationship recorded at the CR position when using digital methods remains uncertain.

PURPOSE

The purpose of this clinical study was to compare the accuracy of the maxillomandibular relationship recorded at the CR position using a conventional procedure, 4 different IOSs, and an optical jaw tracking system.

MATERIAL AND METHODS

A completely dentate volunteer was selected. A Kois deprogrammer (KD) was fabricated. Six groups were created based on the technique used to obtain diagnostic casts and record the maxillomandibular relationship at the CR position: conventional procedures (CNV group), 4 IOS groups: TRIOS4 (TRIOS4 group), iTero Element 5D (iTero group), i700 wireless (i700 group), Primescan (Primescan group), and a jaw tracking system (Modjaw) (Modjaw group) (n=10). In the CNV group, conventional diagnostic stone casts were obtained. A facebow record was used to mount the maxillary cast on an articulator (Panadent). The KD was used to obtain a CR record for mounting the mandibular cast, and the mounted casts were digitized by using a scanner (T710) to acquire the reference scans. In the TRIOS group, intraoral scans were obtained and duplicated 10 times. The KD was used to obtain a bilateral virtual occlusal record at the CR position. To acquire the specimens of the iTero, i700, and Primescan groups, the procedures in the TRIOS4 group were followed, but with the corresponding IOS. In the Modjaw group, the KD was used to record and export the maxillomandibular relationship at the CR position. Articulated virtual casts of each group were exported. Thirty-six interlandmark linear measurements were computed on both the reference and experimental scans. The distances obtained on the reference scan were used to calculate the discrepancies with the distances obtained on each experimental scan. The data were analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey tests (α=.05).

RESULTS

The trueness and precision of the maxillomandibular relationship record were significantly affected by the technique used (P<.001). The maxillomandibular relationship trueness values from high to low were iTero (0.14 ±0.09 mm), followed by the Modjaw (0.20 ±0.04 mm) and the TRIOS4 (0.22 ±0.09 mm) groups. However, the iTero, Modjaw, and TRIOS4 groups were not significantly different from each other (P>.05). The i700 group obtained the lowest trueness and precision values (0.40 ±0.22 mm) of all groups tested, followed by the Primescan grop (0.26±0.13 mm); however, the i700 and Primescan groups had significantly lower trueness and precision than only the iTero group (P<.05).

CONCLUSIONS

The trueness and precision of the maxillomandibular relationship recorded at the CR position were influenced by the different digital techniques tested.

Influence of print orientation and wet-dry storage time on the intaglio accuracy of additively manufactured occlusal devices

STATEMENT OF PROBLEM

Different factors can affect the manufacturing accuracy of additively manufactured dental devices; however, the influence of print orientation and wet-dry storage time on their intaglio accuracy remains uncertain.

PURPOSE

The purpose of this in vitro study was to assess the effect of print orientation (0, 45, 70, and 90 degrees) and wet-dry storage time (0, 30, 60, and 90 days) on the intaglio accuracy of additively manufactured occlusal devices.

MATERIAL AND METHODS

An occlusal device design was obtained in a standard tessellation language (STL) file format (control file) which was used to fabricate all the specimens by using a stereolithography printer (Form 3+) and a biocompatible resin material (Dental LT Clear Resin, V2). Four groups were created based on the print orientation used to manufacture the specimens: 0, 45, 70, and 90 degrees. Each group was divided into 4 subgroups depending on the time elapsed between manufacturing and accuracy evaluation: 0, 30, 60, and 90 days. For the subgroup 0, a desktop scanner (T710) was used to digitize all the specimens. The 30-day subgroup specimens were stored for 30 days with the following daily storage protocol: 16 hours inside a dry lightproof container, followed by 8 hours in artificial saliva (1700-0305 Artificial Saliva) inside the same lightproof container. The specimens were then digitized by following the same procedures used for subgroup 0. For the subgroups 60 and 90, the identical procedures described for subgroup 30 were completed but after 60 and 90 days of storage, respectively. The reference STL file was used to measure the intaglio discrepancy with the experimental scans obtained among the different subgroups by using the root mean square error calculation. Two-way ANOVA and post hoc Tukey pairwise comparison tests were used to analyze the data (α=.05).

RESULTS

Print orientation (P<.001) and usage time (P<.001) were significant predictors of the trueness value obtained. Additionally, the 0-degree print orientation at day 0 group demonstrated the best trueness value among all the groups tested (P<.05). No significant trueness discrepancies were found among the 45-, 70-, and 90-degree print orientation, or among the 30, 60, and 90 days of storage. A significant precision difference was found in the variance between print orientation groups across usage time subgroups.

CONCLUSIONS

The print orientation and wet-dry storage times tested influenced the trueness and precision of the intaglio surfaces of the occlusal devices manufactured with the 3D printer and material selected.

Does the available interocclusal space influence the accuracy of the maxillomandibular relationship captured with an intraoral scanner?

STATEMENT OF PROBLEM

The accuracy of a maxillomandibular relationship acquired by intraoral scanners (IOSs) has been previously analyzed; however, the impact of the interocclusal space on the accuracy of the maxillomandibular relationship remains unknown.

PURPOSE

The purpose of this in vitro investigation was to evaluate the influence of the interocclusal space (0, 1, 2, 3, or 4 degrees of incisal opening in the articulator) on the accuracy of the maxillomandibular relationship captured with an IOS.

MATERIAL AND METHODS

Markers were attached to the first molars and canines of maxillary and mandibular diagnostic casts, which were mounted on a semi-adjustable articulator, and digital scans were acquired (TRIOS 4). Both digital scans were duplicated 100 times and distributed into 5 groups depending on the incisal pin opening in the articulator (n=20): 0 (Group 0), 1 (Group 1), 2 (Group 2), 3 (Group 3), and 4 degrees (Group 4). In Group 0 (control), the casts were maintained in maximum intercuspation (MIP) with the incisal pin of the articulator set at 0 degrees. Then, a bilateral virtual occlusal record was acquired and automatically processed by using the IOS software program. A laboratory scanner (Medit T500) was used to digitize the mounted casts. The same procedures were completed in Groups 1, 2, 3, and 4 but with the incisal pin set at 1, 2, 3, and 4 degrees respectively. The interlandmark distances were used to calculate the discrepancies between the control and groups tested. One-way analysis of variance (ANOVA) and pairwise comparison Tukey HSD tests were used to inspect the data (α=.05).

RESULTS

The interocclusal space available when capturing the occlusal records affected the trueness of the maxillomandibular virtual relationship measured (P<.001). Group 0 (135 μm) obtained the highest distortion, while Group 3 (73 μm) and Group 4 (71 μm) showed the lowest distortion. Additionally, the interocclusal space available (P<.001) impacted the precision of the maxillomandibular virtual relationship measured. Group 0 (111 μm) obtained the highest distortion, while Group 4 (precision mean value of 59 μm) had the lowest distortion among the groups tested.

CONCLUSIONS

The interocclusal space available when acquiring virtual bilateral occlusal records using the IOS tested impacted the accuracy of the maxillomandibular relationship. The smallest available interocclusal space tested (maximum intercuspation) showed the worst trueness and precision mean values, while the group with the largest interocclusal space available had the highest trueness and precision mean values among the groups studied.

Digital maxillomandibular relationship and mandibular motion recording by using an optical jaw tracking system to acquire a dynamic virtual patient

A technique for digitally recording the maxillomandibular relationship, including the maximum intercuspation and centric occlusion and the patient's mandibular motion, by using an optical jaw tracking system is described. Advantages of this technique include the digital registration of the maxillomandibular relationship and mandibular motion. This technique incorporates the mandibular motion into the 3-dimensional (3D) virtual patient representation to integrate the 3D dynamic virtual patient visualization.

Utilizing an additively manufactured Kois deprogrammer to record centric relation: A simplified workflow and delivery technique

A technique for fabricating an additively manufactured Kois deprogrammer is described from the initial patient data collection with an intraoral scanner to the 3D printing methods to fabricate the device. The incorporation of digital technologies for manufacturing a Kois deprogrammer provides new clinical and manufacturing tools, providing more efficient and less time-consuming design and manufacturing techniques than conventional techniques while maintaining conventional prosthodontic concepts.

Accuracy of the 3-dimensional virtual patient representation obtained by using 4 different techniques: An in vitro study

STATEMENT OF PROBLEM

Facial and intraoral scans can be aligned with or without the assistance of extraoral scan body systems to obtain a 3-dimensional (3D) virtual patient representation. However, the accuracy of the virtual patient remains uncertain.

PURPOSE

The purpose of this in vitro study was to measure the accuracy of the virtual patient representation obtained by superimposing facial and intraoral digital scans with 4 different techniques (with and without the usage of extraoral scan bodies) and to measure the operator influence on the accuracy of the virtual patient integration.

MATERIAL AND METHODS

Three markers were placed in the jaw simulation of a mannequin on the right (r), center (c), and left (l) surfaces. Five additional markers were attached to the mesiobuccal cusp of the right first molar (RM), cusp of the right canine (RC), buccal surface of the right central incisor (CI), cusp of the left canine (LC), and mesiobuccal cusp of the left first molar (LM). A reference scan (control scan) of the mannequin was obtained by using an industrial scanner (Gom ATOS Q 3D 12 M). Four different groups were created depending on the technique used: 3D scan body (3D scan body) (3D-SB group), AFT (AFT Dental System) (AFT group), Sat 3D (Sat 3D) (Sat3D group), and without using a scan body system (No-SB group). Additionally, a digital scan of the typodont was obtained with an intraoral scanner (TRIOS 4). The virtual patient integration was performed 10 times per group by 2 independent operators by using a software program (DentalCAD, Galway). Each operator obtained a total of 9 interlandmark measurements on the reference scan and on each virtual patient integration of each group with the measurement tool of the computer-aided design program. The data were analyzed by using 4-way ANOVA followed by the pairwise comparison Tukey tests (α=.05).

RESULTS

The group (P<.001), specimen (P<.001), and operator (P<.001) significantly influenced the trueness discrepancies obtained. Additionally, the 3D-SB group had the best trueness (244 μm), and the No-SB group had the worst trueness (346 μm). Operator 1 (279 μm) obtained significantly better trueness than operator 2 (295 μm). Group (P<.001), specimen (P<.001), and operator (P<.001) significantly influenced precision discrepancies, with the AFT (149 μm) and 3D-SB (154 μm) groups having the best precision and the No-SB group (269 μm) the worst precision. Operator 1 (176 μm) obtained significantly better precision than operator 2 (197 μm).

CONCLUSIONS

The techniques tested influenced the accuracy of the 3D virtual patient representation. The 3D-SB group had the best trueness, and the AFT and 3D-SB groups had the best precision, while the No-SB group showed the lowest trueness and precision values. Operator handling had a significant effect on the trueness and precision values of the virtual patient integrations tested.

Scan body system to translate natural head position and virtual mounting into a 3-dimensional virtual patient: A dental technique

Various techniques have been developed for a 3-dimensional (3D) virtual patient. However, those techniques do not enable the registration of the alignment of the facial and intraoral digital scans, the registration for the mounting on the virtual articulator, and the integration of the natural head position (NHP) together. In the present manuscript, a scan body system is described that assists with the translation of the horizon orientation within the NHP of the patient into a computer-aided design software program. Additionally, the scan body system facilitates the facial and intraoral alignment, as well as the mounting of the maxillary virtual cast on the virtual articulator. This scan body system facilitates the integration of the 3D virtual patient and reduces chair and laboratory time.

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position

Although the evolution of digital technology continues to improve patient data acquisition, the ability to both standardize the recording of the maxillary occlusal plane and capture the necessary dynamic data for dento-facial analysis remains elusive. This article describes step-by-step techniques to position the maxilla on an articulator using the natural head position and a facial reference system (Kois Facial Reference Glasses) for both analog and digital workflows. A photographic technique will be presented that captures the natural head position and allows the clinician to align a 2D reference photograph with the maxillary intraoral digital scan and the virtual articulator. Using this reference photograph, the clinician can record and communicate to the technician the maxillary arch position in relationship with the facial references, as well as transfer the additively manufactured casts in the same facial orientation for mounting and analysis either virtually or on an analog articulator. This article is protected by copyright. All rights reserved.