Comparison of the accuracy of different types of bite recordings - an in vitro study.

OBJECTIVES: Reconstruction of a three-dimensional jaw position determined by a bite recording is an important aspect of prosthetic therapy. Different materials are used for this purpose. In the dental technical workflow, recordings are used to mount a lower jaw cast in a patient-like spatial position relative to the upper jaw cast. We evaluated the accuracy of positioning under the influence of different jaw positions and materials. MATERIALS AND METHODS: In an experimental setup, comprising an articulator, a pair of metal casts, and an optoelectronic measurement system, the spatial position of the incisal point and two condylar points were measured. To evaluate the accuracy of repeated repositioning of casts in the technical workflow, 324 measurements were taken from 108 recordings, consisting of silicone bite-stops made of addition curing silicone with 95 shore hardness, acrylic wafers, and wax recordings. The recordings were obtained in four jaw relations differing in vertical and protrusive components. RESULTS: Of the three materials/material combinations examined, silicone showed the most consistent results across all measurements, followed by the acrylic wafer system, and then wax recordings. Generally, recordings with smaller gaps between the jaws and no protrusive components showed greater deviations compared to jaw positions with greater protrusion and higher vertical dimensions. CONCLUSIONS AND CLINICAL RELEVANCE: To achieve reliable model mounting with high accuracy, recordings should include the use of a frontal jig and four small recording platelets made of silicone, especially if only a slight elevation of the vertical dimension is needed.

Evaluation of the accuracy of a fully digital method of measuring sagittal condylar inclination.

OBJECTIVES: This clinical study aimed to evaluate the accuracy of a fully digital technique for measuring sagittal condylar inclination (SCI), as well as validating whether differences existed between the left and right SCI values of the same participant, to provide a reference for clinical practice. METHODS: Ten participants with good occlusal relationship and normal temporomandibular joint were recruited. Three methods were used to measure the SCI values of the participants, namely, A (mechanical facebow transferring and mechanical articulator-based measuring method with physical protrusive interocclusal registration), B (face scan-based virtual facebow and virtual articulator-based measuring method with digital protrusive interocclusal registration), and C (jaw motion tracking system-based measuring method). With the group subjected to methods A and C as the control, the SCI values obtained by the three methods were statistically analyzed. The left and right SCI values of the same participant were also compared. RESULTS: The left and right SCI values measured by method A were 41.70°±7.09° and 42.80°±8.62°, those by method B were 35.09°±12.49° and 37.63°±12.10°, and those by method C were 39.43°±8.72° and 38.45°±6.91°. No significant difference existed among the SCI values measured by the three methods (P>0.05). Meanwhile, no statistical difference existed between the SCI values on the left and right sides of the same participant (P>0.05). CONCLUSIONS: The accuracy of the virtual facebow and digital protrusive occlusal registration based SCI measuring method was the same as that of mechanical facebow based and jaw motion tracking system-based methods. The SCI values on the left and right sides of the same participant were similar. Clinically, an appropriate SCI measurement and setting strategy can be selected based on the actual situations.

Digital application of three-dimensional diagnosis and treatment with a virtual articulator.

OBJECTIVE: The purpose of this article was to introduce a method for the digital application of three-dimensional (3D) diagnosis and treatment with a virtual articulator and 3D data. CLINICAL CONSIDERATION: With the use of cone-beam computed tomography (CBCT) and intraoral and facial scans, we can create a virtual articulator and evaluate the mandibular position in maximum intercuspation and centric-related occlusion for the patient with an unstable occlusion and temporomandibular disorders (TMD). Based on this, we treated a case using a digital mandibular position indicator (MPI) and fabricated a stabilization splint using a 3D printer. This approach eliminates the traditional impression or model mounting process and the analog face bow transfer. Furthermore, the design of the stabilization splint is accomplished using software. CONCLUSIONS: The approach outlined in this article offers the potential for a digital diagnosis and treatment process by seamlessly integrating CBCT, intraoral scans, and facial scans with a high degree of accuracy. This may enhance precision in diagnosis and treatment planning, especially for patients with complicated TMD, in addition to facilitating effective communication with orthodontic patients who require thorough attention. CLINICAL SIGNIFICANCE: Utilizing a virtual articulator and digital MPI for the occlusal evaluation of patients with TMD and unstable occlusion makes it possible to diagnose and analyze the occlusal condition accurately. This approach also allows for precision and efficiency in treatment.

Evaluation of accuracy between extraoral Gothic arch tracing and various other methods assessing horizontal condylar guidance angle in completely edentulous patients: A systematic review and meta-analysis.

Aim: The aim of this systematic review and meta-analysis was to determine the accuracy of different methods of measuring horizontal condylar guidance (HCG) angle in comparison with extraoral Gothic arch tracing for completely edentulous patients. Settings and Design: This was a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Materials and Methods: Two reviewers searched the EBSCOhost, Cochrane Library, and PubMed/MEDLINE databases and the Google Scholar search engine for in vivo studies, randomized controlled trials, cross-sectional studies, and quasi-experimental studies published from January 2005 to December 2022 on various other methods of determining HCG angle in completely edentulous patients compared with extraoral Gothic arch tracing method. Statistical Analysis Used: Meta-analysis was conducted from the reported quantitative data. Results: A total of 513 articles were obtained from different electronic databases, of which 22 studies were included for qualitative synthesis and 20 studies were included for meta-analysis. For the right side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.08 [2.17, 7]) and cephalogram (P < 0.05, pooled mean difference = 10.65 [8.81, 12.49]), whereas no statistically significant difference was observed for cone-beam computed tomography (CBCT) (P = 0.41, pooled mean difference = 4.39 [-6.10, 14.87]) and protrusive interocclusal wax record (P = 0.92, pooled mean difference = -0.45 [-9.62, 8.72]) as compared with extraoral Gothic arch tracing method. For the left side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.07 [1.95, 8.18]) and cephalogram (P < 0.05, pooled mean difference = 10.24 [8.65, 11.83]), whereas no statistically significant difference was observed for CBCT (P = 0.31, pooled mean difference = 4.05 [-3.74, 11.84]) and protrusive interocclusal wax record (P = 0.72, pooled mean difference = -1.21 [-7.86, 5.43]) as compared with extraoral Gothic arch tracing method. Conclusion: The cephalogram and panoramic radiograph obtained higher HCG angles in completely edentulous patients than extraoral Gothic arch tracing.

Comparative Evaluation of the Horizontal Condylar Guidance Using Protrusive Interocclusal Records, OPG, and CBCT in Edentulous Patients: An In Vivo Study.

AIMS: A clinical study to compare the horizontal condylar guidance using protrusive interocclusal records, orthopantomography (OPG), and cone-beam computed tomography (CBCT) in edentulous patients. SUBJECTS AND METHODS: Thirty-six edentulous subjects were selected as per predetermined criteria. Horizontal condylar guidance was recorded using protrusive interocclusal records (PIR), OPG, and CBCT for each patient. The PIR were obtained using extraoral Gothic arch tracers to program the Hanau articulator. The horizontal condylar guidance angles (HCGAs) were digitally constructed using appropriate software along the posterior slope of articular eminence for all radiographs. The collected data were recorded, tabulated, and statistically analyzed. RESULTS: The condylar guidance angle values were tested for significance to compare the different angles. The correlation of HCGA measurements on both sides between the three groups was analyzed. The PIR and OPG methods (p = 0.001), as well as the OPG and CBCT methods (p = 0.001), show substantial differences on both sides. On the contrary, the PIR and CBCT methods did not differ significantly (p = 0.11). CONCLUSION: Cone-beam computed tomography is as reliable and accurate as the clinical method. A significant correlation exists between the clinical method and CBCT. It can be used as a dependable adjunct to the clinical method of HCGA measurement. CLINICAL SIGNIFICANCE: Cone-beam computed tomography can overcome the shortcomings of the conventional clinical methods to determine the accurate horizontal condylar guidance angulation measurement. It is safer with minimum discomfort and wastage of time for the patients.

Preliminary clinical study of the accuracy of a digital axiographic recording system for the assessment of sagittal condylar inclination.

OBJECTIVES: The aim of this study was to clinically evaluate the accuracy of a digital axiographic recording system in tracing the sagittal condylar inclination. METHODS: An axiographic examination that records the sagittal condylar path during protrusive/retrusive movement was performed on ten patients. Each subject was registered five different times by two different systems: 1) the Cadiax Gamma Diagnostic 4 computerized system as the control; 2) the Zebris Jaw Motion Analyser+  Optic System as the tested digital axiographic recording system. The records obtained allow to calculate the kinematic terminal transverse horizontal axis and the sagittal condylar inclination (SCI) at 3 and 5 mm along the pro-retrusive path. A linear mixed model was used to analyze if there was a statistically significant difference between the two systems. RESULTS: The mean left SCI value recorded by Zebris system were 49.81 ± 10.64° at 3 mm, 48.10 ± 11.04° at 5 mm, while the values recorded by Gamma system were 55.16° at 3 mm, 52.18° at 5 mm. The mean right SCI value recorded by Zebris system were 54.53 ± 10.26° at 3 mm, 51.85 ± 8.55° at 5 mm, while the values recorded by Gamma system were 49.68° at 3 mm, 48.23° at 5 mm. Linear mixed model showed no significant statistical difference between the two systems. CONCLUSIONS: Based on preliminary results, the Zebris Jaw Motion Analyzer+ Optic System demonstrates comparable accuracy to the Cadiax Gamma Diagnostic 4 when measuring sagittal condylar inclination. CLINICAL SIGNIFICANCE: The digital axiographic recording system enables to evaluate sagittal condylar inclination and to adjust virtual articulators in a digital workflow.

A fully digital workflow to register maxillomandibular relation using a jaw motion tracer for fixed prosthetic rehabilitation: A technical report.

OBJECTIVE: This technique aimed to describe a fully digital workflow to register maxillomandibular relation for fixed prosthetic rehabilitation. CLINICAL CONSIDERATIONS: Mandibular kinematics could be reproduced in a four-dimensional (4D) virtual patient based on the intraoral scan, facial scan, cone beam computed tomography, and jaw motion trajectory, which helped record centric relation and determine a proper occlusal vertical dimension in a virtual environment. The therapeutic position could be exported directly to the dental computer-aided design software for digital waxing design with a facial scan. The 4D virtual patient was also used to verify the functional and esthetic outcomes of provisional restorations. CONCLUSIONS: This novel approach digitized the process of determination, delivery, and double-check of maxillomandibular relation, thus contributing to the establishment of a completely digital workflow for fixed prosthetic rehabilitation. CLINICAL SIGNIFICANCE: Registration of maxillomandibular relation, including centric relation and occlusal vertical dimension is critical to the success of prosthetic rehabilitation. Traditional procedures are complex and time-consuming, and heavily rely on the clinical experience of dentists. A fully digital approach to creating a 4D virtual patient and registering the maxillomandibular relation is established, which guides to determine a proper occlusal vertical dimension in centric relation. Digital delivery and double-check can simplify the conventional procedure and ensure that the determined maxillomandibular relation is reliable.

Comparison of the performance of various virtual articulator mounting procedures: a self-controlled clinical study.

OBJECTIVES: This clinical study aimed to compare the performance of various virtual articulator (VA) mounting procedures in the participants' natural head position (NHP). MATERIALS AND METHODS: Fourteen participants with acceptable dentitions and jaw relationships were recruited in this study registered in the Clinical Trials Registry (#NCT05512455; August 2022). A virtual facebow was designed for virtual mounting and hinge axis measurement. Intraoral scans were obtained, and landmarks were placed on each participant's face to register the horizontal plane in NHP. Six virtual mounting procedures were performed for each participant. The average facebow group (AFG) used an indirect digital procedure by using the average facebow record. The average mounting group (AMG) aligned virtual arch models to VA's average occlusal plane. The smartphone facial scan group (SFG) and professional facial scan group (PFG) used facial scan images with Beyron points and horizontal landmarks, respectively. The cone-beam computed tomography (CBCT) scan group (CTG) used the condyle medial pole, and horizontal landmarks were applied. The kinematic facebow group (KFG) served as the control group, and a direct digital procedure was applied using a kinematic digital facebow and the 3D skull model. Deviations of the reference plane and the hinge axis between the KFG and other groups were calculated. The inter-observer variability in virtual mounting software operation was then evaluated using the interclass correlation coefficient (ICC) test. RESULTS: In virtual condylar center deviations, the CTG had the lowest condylar deviations. The AFG showed larger condylar deviations than PFG, SFG, and CTG. There was no statistically significant difference between the AFG and the AMG and between the PFG and the SFG. In reference plane deviations, the AMG showed the largest angular deviation (8.23 ± 3.29°), and the AFG was 3.89 ± 2.25°. The angular deviations of PFG, SFG, and CTG were very small (means of each group < 1.00°), and there was no significant difference among them. There was no significant difference between the researchers, and the ICC test showed moderate to excellent reliability for the virtual condylar center and good to excellent reliability for the reference plane in the operation of the virtual mounting software. CONCLUSIONS: CBCT scan provided the lowest hinge axis deviation in virtual mounting compared to average mounting, facebow record, and facial scans. The performance of the smartphone facial scanner in virtual mounting was similar to that of the professional facial scanner. Direct virtual mounting procedures using horizontal landmarks in NHP accurately recorded the horizontal plane. CLINICAL RELEVANCE: Direct digital procedures can be reliably used for virtual articulator mounting. The use of a smartphone facial scanner provides a suitable and radiation-free option for clinicians.

Number of occlusal contacts during maximum intercuspation in dentate adults: A systematised review.

BACKGROUND: Evaluating occlusal contacts during maximum intercuspation is one of the requirements for guiding clinicians during occlusal corrections and has been a topic of considerable importance for researchers over many decades. OBJECTIVE: This systematised review intends to evaluate the average number of occlusal contacts present in dentate adults, as documented within the dental literature over the past four decades (1980s-2022). METHODOLOGY: Electronic searches were conducted in three databases (PubMed, Livivo and Ovid) using a combination of search words. RESULTS: A total of 651 records were identified through PubMed and another 37 records through Livivo and Ovid databases. After eliminating duplicates and irrelevant records, 168 records were screened. Full texts of 61 articles remained, out of which 18 relevant papers that presented occlusal contacts in quantifiable value were considered. Various occlusal indicators, such as articulating paper, wax sheets, shimstock foil, impression material, gnathodynamometers and digital occlusal analysis systems, were used to evaluate occlusal contacts. The number of occlusal contacts widely ranged from 11 to 70. These variations likely depends upon the type and technique of occlusal indicator used, diversity among sampled populations and differing data collection procedures. CONCLUSION: Different methods of identifying occlusal contacts in the intercuspal position yield different numbers and patterns of contacts, depending on the nature and physical properties of the indicators used.

Evaluation of dimensional stability, compressive resistance, and detail reproduction of thermoplastic resin (BDIMPRESS), elastomeric and composite bite registration material: An in vitro study.

Aim: The fabrication of an accurate prosthesis depends mainly on precise recording of the maxillo-mandibular relationship of the patient and transferring it to the articulator. BDIMPRESS is a new thermoplastic material that has been proposed as a potential material to be used as an inter-occlusal registration, but there has been no literature evidence regarding its application as a bite registration. The main purpose of this study is to evaluate and compare the dimensional stability, detail reproduction, and compressive resistance of new interocclusal recording material with other two commonly used materials. Settings and Design: In Vitro Comparative study. Materials and Methods: The study was conducted according to ADA Specification standards of testing for dimensional stability, detail reproduction and compressive resistance. Specimens were prepared for three different materials (Thermoplastic resin, Polyvinyl siloxane, and Bis- acrylic) with 12 samples each. Statistical Analysis Used: One way ANOVA was done for statistical analysis. Results: Polyvinyl siloxane material was dimensionally stable (mean at 1 hr: 24.928 mm; 24 hrs: 24.919 mm & 48 hrs: 24.912 mm) followed by Bis- acrylic material (mean at 1 hr: 24.851 mm; 24 hrs: 24.825 mm & 48 hrs: 24.815 mm). On one way ANOVA, strong significance was observed between groups (P = 0.00). Thermoplastic resin showed higher amount of detail reproduction with 10 (out of 12 samples) samples showing satisfactory results. While bis- acrylic material showed the least compressive resistance (Strain %: 0.484%; Displacement- 0.0990mm). One-way ANOVA showed presence of significance between the groups (P = 0.024). Conclusion: Polyvinyl siloxane showed superior dimensional stability, thermoplastic resin showed better detail reproduction and bis- acrylic showed high resistance to compression over other materials.

[A clinical application study of digital manufacturing simple intraoral Gothic arch-tracing device in determining the centric relation of complete dentures].

OBJECTIVE: To verify the consistency between the digital manufacturing simple intraoral Gothic arch-tracing device and the traditional intraoral Gothic arch-tracing device in determining the centric relation of complete dentures restoration. METHODS: Ten outpatients with edentulous jaws were selec-ted, and the centric relation of the patients was determined by digital manufacturing of simple intraoral Gothic arch-tracing device (T1) and traditional intraoral Gothic arch-tracing device (T2); the difference of clinical operation time between the two methods was recorded; the upper and lower edentulous jaw plaster models were scanned with two kinds of centric relation, the Standard Triangle Language (STL) files imported into Geomagic studio software to apply the best fitting of multiple points of the both upper jaw models, the fitted STL files imported into the 3 shape viewer software, and the maximum position deviations of the vertical, labial (buccal) and lingual directions of the mandibular midline area and molar areas in T1 and T2 groups measured. During the clinical complete dentures try-in, we observed whether there was midline deviation in the mouth of T1 group and T2 group, and whether the occlusion of posterior teeth was stable or not. RESULTS: The mean time spent on determining the centric relation of T1 and T2 groups was (41.90±2.64) min, (57.50±2.37) min respectively. Paired t test was conducted in the two groups, P < 0.01 with significant statistical difference; The mean maximum position deviation between T1 group and T2 group of the midline mandibular region in labial lingual direction was (0.32±0.14) mm, that was (0.40±0.23) mm in vertical direction; the mean maximum position deviation of molar area in buccal lingual direction was (0.35±0.23) mm and that was (0.33±0.20) mm in vertical direction. In the vertical and horizontal directions, the maximum position deviation of mandibles between group T1 and group T2 was controlled within 0.5 mm. In the process of clinical complete dentures try-in, there was no deviation from the center line of dentures. There was not warping, swinging and other poor stability phenomena in T1 and T2 groups. CONCLUSION: The digital manufacturing of simple intraoral Gothic arch-tracing device can be used to determine the centric relation of complete dentures, which can not only save time of clinical operation, but also ensure the accuracy of the centric relation.

Fully digital workflow for replicating treatment dentures: A technique for jaw relation transfer and dynamic occlusal adjustment.

This technique report presents a novel method of digitally replicating a treatment denture and converting it into a definitive denture. The procedure accurately duplicates the appearance of the mucosal surface and border of the treatment dentures, mounts the jaw relation on a virtual articulator to arrange artificial teeth, and optimizes the occlusion based on recorded mandibular motion tracks. This technique uses personalized jaw relation transfer and dynamic occlusal adjustment to establish balanced occlusion, which accomplishes the digital duplication of the treatment denture with high accuracy and minimal effort.

Centric relation: A needed reference position.

PURPOSE: Centric relation (CR) is a universally recognized term and an acceptable reference position with a long history of success. The problem is that there is little consensus as to its definition or the method of recording it, and this has created an uprising to abolish it. METHODS: A review of pertinent literature related to its definition, method of recording, anatomic considerations, and long-standing principles was conducted. RESULTS: Centric relation is an established term but there are valid concerns over its definition and method of recording. There is consensus on using it as a restorative position in a patient in need of full-arch reconstruction, and there is no substantive clinical research to contradict this. If a clinician decides to use a different position, it should have a different name. CONCLUSIONS: Centric relation is a reproducible reference position that can be utilized for diagnostic and restorative dental procedures with substantial scientific evidence to support that premise. There are numerous well-documented techniques, all of which are intermaxillary, that can replicate the position. There is little scientific evidence to support a premise as to where the exact position of the condyle should be in relation to the fossa.

Variables influencing the device-dependent approaches in digitally analysing jaw movement-a systematic review.

BACKGROUND: To explore the digitisation of jaw movement trajectories through devices and discuss the physiological factors and device-dependent variables with their subsequent effects on the jaw movement analyses. METHODS: Based on predefined eligibility criteria, the search was conducted following PRISMA-P 2015 guidelines on MEDLINE, EBSCO Host, Scopus, PubMed, and Web of Science databases in 2022 by 2 reviewers. Articles then underwent Cochrane GRADE approach and JBI critical appraisal for certainty of evidence and bias evaluation. RESULTS: Thirty articles were included following eligibility screening. Both in vitro experiments (20%) and in vivo (80%) devices ranging from electronic axiography, electromyography, optoelectronic and ultrasonic, oral or extra-oral tracking, photogrammetry, sirognathography, digital pressure sensors, electrognathography, and computerised medical-image tracing were documented. 53.53% of the studies were rated below "moderate" certainty of evidence. Critical appraisal showed 80% case-control investigations failed to address confounding variables while 90% of the included non-randomised experimental studies failed to establish control reference. CONCLUSION: Mandibular and condylar growth, kinematic dysfunction of the neuromuscular system, shortened dental arches, previous orthodontic treatment, variations in habitual head posture, temporomandibular joint disorders, fricative phonetics, and to a limited extent parafunctional habits and unbalanced occlusal contact were identified confounding variables that shaped jaw movement trajectories but were not highly dependent on age, gender, or diet. Realistic variations in device accuracy were found between 50 and 330 µm across the digital systems with very low interrater reliability for motion tracing from photographs. Forensic and in vitro simulation devices could not accurately recreate variations in jaw motion and muscle contractions.

Clinical reproducibility of different centric relation recording techniques in edentulous individuals: An observational cross-sectional study.

PURPOSE: To assess the reproducibility of four different centric relation (CR) recording techniques, and time spent performing each technique in edentulous individuals. MATERIALS AND METHODS: Four techniques were assessed: extraoral gothic arch (EOGA) tracing, intraoral gothic arch (IOGA) tracing, deglutition (D), and frontal manipulation with tongue elevation (FMTE). Twelve subjects participated in the study; four technique records were performed on each volunteer by the same operator. Each record was repeated three times, in the same period of the day, with a 30 min interval between each technique. The reproducibility of each technique was assessed by the tri-dimensional displacement of the position of the condylar housing (mandible condyle) to the wall of the condylar guide (glenoid cavity) in the semi-adjustable articulator (anteroposterior, mediolateral, and superior-inferior). The time spent on each technique was timed in seconds (from the beginning of each technique until the wax occlusion fixation). The analysis of variance (ANOVA) and the Tukey test were performed for anteroposterior displacement (two-way) and for time spent on CT recording techniques (one-way) (α < 0.05). Regarding mediolateral and superior-inferior displacements, the nonparametric Kruskal-Wallis was performed for the comparison between recording methods, whereas the Mann-Whitney test was performed for the comparison between sides (α < 0.05). RESULTS: The factor recording technique interfered with the anteroposterior displacement (ANOVA: α < 0.001; F = 11.396). The technique D (right side: 3.78 ± 0.69 mm; left side: 3.45 ± 0.74 mm) showed a statistically significant difference compared to the other techniques (EOGA: right side: 3.00 ± 0.00 mm; left side: 3.00 ± 0.00 mm; FMTE: right side: 2.81 ± 0.52 mm; left side: 2.82 ± 0.79 mm; IOGA: right side: 2.90 ± 0.65 mm; left side: 3.12 ± 0.44 mm). The time spent on the recording technique influenced the results (ANOVA: α < 0.001; F = 21.118). The IOGA (340.40 ± 163.41 s) and EOGA (285.93 ± 133.84 s) required more time compared to the D (86.00 ± 34.33 s) and FMTE (101.33 ± 36.72 s) techniques. CONCLUSION: Graphic recordings showed better reproducibility and accuracy of the position of the centric relation.

In Vitro Assessment of Dimensional Accuracy of Three Different Types of Interocclusal Recording Materials.

AIM: The aim of the current study was to evaluate the dimensional accuracy of three various interocclusal recording materials. MATERIALS AND METHODS: A total of 90 disc-shaped samples were prepared using polyether paste, wax, and polyvinyl siloxane material with the support of stainless steel die. For the purposes of this investigation, three frequently utilized interocclusal recording materials were chosen, and 30 samples from each material were prepared. Group I: Bite registration using polyether paste; Group II: Bite registration using wax; Group III: Bite registration using polyvinyl siloxane material. No samples were exposed to direct sunlight during storage and were kept at room temperature. Using a 10x universal measuring microscope, each sample disc was examined for the presence of horizontal and vertical lines inscripted in the die. For each of the samples, readings were taken at different time periods of 24, 48, and 72 hours. RESULTS: After 24 hours, the less dimensional changes were found in polyether paste group (0.11 ± 0.07) followed by polyvinyl siloxane material group (0.19 ± 0.04) and wax group (0.25 ± 0.12). After 48 hours, the less dimensional changes were found in polyether paste group (0.34 ± 0.02) followed by polyvinyl siloxane material group (0.42 ± 0.01) and wax group (0.94 ± 0.12). After 72 hours, the least dimensional changes were found in polyether paste group (0.46 ± 0.14) followed by polyvinyl siloxane material group (0.92 ± 0.03) and wax group (1.14 ± 0.09). CONCLUSION: The present study concluded that both the material and time factors had an impact on dimensional stability. The most dimensionally stable group was the polyether paste group, which was followed by the polyvinyl siloxane and wax material groups. CLINICAL SIGNIFICANCE: Interocclusal recording material records the occlusal connection between real or artificial teeth for occlusal rehabilitation planning and for creating removable and fixed dentures. The creation of a clinically acceptable prosthesis is dependent upon the accuracy of the patient's diagnostic or working casts and the interocclusal record. How to cite this article: Sonkesriya S, Subramanian D, Saha P, et al. In Vitro Assessment of Dimensional Accuracy of Three Different Types of Interocclusal Recording Materials. J Contemp Dent Pract 2023;24(12):936-939.

A clinical application study of digital manufacturing simple intraoral Gothic arch-tracing device in determining the centric relation of complete dentures / 北京大学学报(医学版)

OBJECTIVE@#To verify the consistency between the digital manufacturing simple intraoral Gothic arch-tracing device and the traditional intraoral Gothic arch-tracing device in determining the centric relation of complete dentures restoration.@*METHODS@#Ten outpatients with edentulous jaws were selec-ted, and the centric relation of the patients was determined by digital manufacturing of simple intraoral Gothic arch-tracing device (T1) and traditional intraoral Gothic arch-tracing device (T2); the difference of clinical operation time between the two methods was recorded; the upper and lower edentulous jaw plaster models were scanned with two kinds of centric relation, the Standard Triangle Language (STL) files imported into Geomagic studio software to apply the best fitting of multiple points of the both upper jaw models, the fitted STL files imported into the 3 shape viewer software, and the maximum position deviations of the vertical, labial (buccal) and lingual directions of the mandibular midline area and molar areas in T1 and T2 groups measured. During the clinical complete dentures try-in, we observed whether there was midline deviation in the mouth of T1 group and T2 group, and whether the occlusion of posterior teeth was stable or not.@*RESULTS@#The mean time spent on determining the centric relation of T1 and T2 groups was (41.90±2.64) min, (57.50±2.37) min respectively. Paired t test was conducted in the two groups, P < 0.01 with significant statistical difference; The mean maximum position deviation between T1 group and T2 group of the midline mandibular region in labial lingual direction was (0.32±0.14) mm, that was (0.40±0.23) mm in vertical direction; the mean maximum position deviation of molar area in buccal lingual direction was (0.35±0.23) mm and that was (0.33±0.20) mm in vertical direction. In the vertical and horizontal directions, the maximum position deviation of mandibles between group T1 and group T2 was controlled within 0.5 mm. In the process of clinical complete dentures try-in, there was no deviation from the center line of dentures. There was not warping, swinging and other poor stability phenomena in T1 and T2 groups.@*CONCLUSION@#The digital manufacturing of simple intraoral Gothic arch-tracing device can be used to determine the centric relation of complete dentures, which can not only save time of clinical operation, but also ensure the accuracy of the centric relation.

An Indirect Digital Technique to Transfer 3D Printed Casts to a Mechanical Articulator With Individual Sagittal Condylar Inclination Settings Using CBCT and Intraoral Scans.

With the widespread application of digital impression techniques in prosthetic dentistry, accurate intraoral scan mounting, and virtual articulator parameters setting as per patients' anatomic structures are essential for treatment planning and restoration fabrication, especially for complex rehabilitation cases; meanwhile, marginal fit checking, occlusal adjustment, and porcelain layering of restorations are also crucial procedures in all cases in which the analog procedure to mount maxillary arches on a mechanical articulator is still required. This technique article presents an indirect digital approach that can first achieve virtual intraoral scan mounting and sagittal condylar inclination value setting of an Artex virtual articulator based on bony structures provided by a single cone beam computed tomography scan. It then facilitates the transfer of virtually mounted intraoral scans from the virtual articulator to the matched Artex mechanical articulator by relating a digitally scanned mounting plate of the Artex mechanical articulator to the virtual articulator, printing the intraoral scan and mounting plate scan assembly, and then mounting the printed casts on the mechanical articulator based on the printed mounting plate. This technique eliminates the conventional facebow transfer and protrusive bite registration procedures and offers a straightforward approach for the seamless integration of virtual environments and analog workflows into clinical practice. It aids in the design of restorations that are harmonious with the mandibular movements and reduces chairside adjustment time.

Condylar repositioning according to digital bite registration method for virtual orthognathic surgery planning: A series of 49 consecutive patients.

INTRODUCTION: The accurate mandibular condylar positioning for orthognathic surgical planning is fundamental in obtaining a planned occlusal result. The differences between the position of condyles seen on computed tomography or cone-beam computed tomography (CBCT) scans and during surgery reduce the accuracy of the result. This study aimed to assess the differences between the condylar position recorded on CBCT and a numerical 3-dimensional (3D) model created after mandibular repositioning for orthognathic surgery planning. METHODS: This study retrospectively evaluated 49 patients who underwent virtual orthognathic surgery planning. The procedure involved recording a computed tomography or CBCT of the skull and dental surface using an intraoral digital scanner. The mandible was repositioned on the numerical 3D model according to the superimposed virtual bite registration in centric relation. Linear and angular measurements of the right and left condyles were recorded before and after mandibular repositioning. RESULTS: The positions of 98 condyles were compared. Linear measurements of the posterior and superior joint spaces revealed a significant difference. Subgroup analyses displayed statistically significant differences for patients with skeletal Class II malocclusion. CONCLUSION: According to the digital bite registration method, the difference between the mandibular position recorded on CBCT and on the numerical 3D model after repositioning may have clinical significance. Further studies are needed to validate this theory and test the accuracy of the clinical results.

[Assessment of adaptive mechanisms to obturators of the upper jaw according to the data of electronic axiography and cone-beam computer tomography]. / Otsenka adaptatsii k obturiruyushchim protezam verkhnei chelyusti po dannym elektronnoi aksiografii i konusno-luchevoi komp'yuternoi tomografii.

THE AIM OF THE STUDY: Was to assess the adaptation of patients to obturator at different periods of adaptation using objective digital methods of analysis: axiography, cone-beam computer tomography, digital facial scans, and intraoral scanning. MATERIAL AND METHODS: The study comprised 17 patients with postoperative defects of the upper jaw at different periods of removable obturators usage. RESULTS: In 88.2% of the subjects limited mouth opening and displacement of the mandible to the healthy side was detected. Contracture as a complication can develop in the later stages of rehabilitation. CONCLUSION: A long-term rehabilitation of patients is recommended using simulators and special gymnastic exercises in order to prevent extra-articular contracture.