Complete assessment of occlusal dynamics and establishment of a digital workflow by using target tracking with a three-dimensional facial scanner

A fully digital workflow to design anterior guidance for an implant-supported single crown using a modified patient-specific motion technique

Current methods for designing anterior guidance of anterior fixed prostheses are either complicated or lack accuracy. The article describes a fully digital workflow to design individualized anterior guidance of an implant-supported single crown by using a modified patient-specific motion technique. The technique aims to optimize the digital occlusal design workflow, thereby improving the occlusal fit and long-term stability of anterior fixed prostheses.

Is dynamic occlusal design necessary for anterior guidance recovery in the computer-aided design process? An in vitro study

OBJECTIVES

This study aimed to assess the effectiveness of patient-specific motion in restoring anterior guidance and to investigate the influence of occlusal plane position within a virtual articulator on the design of the anterior guide slope for incisors.

METHODS

Twenty participants' intraoral scan, occlusal plane position, and jaw motion data were recorded. The maxillary anterior teeth were virtually prepared, and the crowns were designed based on average virtual articulator (AVR), personalized virtual articulator (ART), and patient-specific motion (PSM). The anterior guide slope of maxillary central incisors (S1, S2, Sc, Sp) and the mesio-distal angle (MDA) of the canine of prostheses were compared to that of natural teeth (NAT). One-Way ANOVA was utilized to evaluate the effectiveness of the three methods in restoring the anterior guidance of maxillary anterior teeth.

RESULTS

The comparison of Sp and MDA showed no significant difference between the PSM and NAT groups (p > 0.05). However, Sp of the ART group was significantly smaller, while MDA was higher than that of the NAT group (p < 0.05). Sp did not differ significantly (p > 0.05) when the angle of the occlusal plane (AOP) was small. As the AOP increased, Sp of the ART and AVR groups were significantly smaller than that of the NAT group (p < 0.05). With a large AOP, Sp of the ART group was notably smaller than that of the NAT group (p < 0.05), while there was no significant difference between the AVR and NAT groups (p > 0.05).

CONCLUSIONS

Occlusal design based on patient-specific motion proved more effective in restoring natural anterior guidance. The anterior guidance of prostheses designed using a virtual articulator was influenced by occlusal plane position.

CLINICAL SIGNIFICANCE

The utilization of a jaw motion tracer facilitated the transfer of personalized occlusal plane positions and recorded jaw motion, which can be integrated into the digital prosthetic workflow for virtual occlusion adjustment. Occlusal design based on patient-specific motion more effectively restored lingual guidance of maxillary anterior crowns.

Jaw tracking integration to the virtual patient: A 4D dynamic approach

This dental technique describes a novel cost-effective workflow for integrating mandible kinematics into a static virtual patient. Computed tomography data are segmented and merged with intraoral surface scans and a target tracking video reproducing the mandible movements. A 4-dimensional dynamic virtual patient is created by using an open-source software program, and all patient-specific parameters can be exported for individualization of a virtual or analog articulator.

Comparison of the accuracy of a cone beam computed tomography-based virtual mounting technique with that of the conventional mounting technique using a facebow

STATEMENT OF PROBLEM

The introduction of digital technology in dentistry has resulted in a shift from conventional methods to digital techniques. However, mounting a digitized dental cast on a virtual articulator is challenging. Several techniques have been suggested to resolve this problem, but in the absence of a standardized method, digitized dental casts are often mounted arbitrarily on a virtual articulator.

PURPOSE

The purpose of this clinical study was to compare the accuracy of a novel virtual facebow transfer (VM) technique based on cone beam computed tomography (CBCT) with that of the conventional mounting (CM) technique using a facebow.

MATERIAL AND METHODS

Five repeated mountings were performed with each technique for 15 participants. In the CM group, dental casts were mounted using a facebow record and scanned for transmission to the virtual dental space. In the VM group, digital dental casts were mounted on the standard tessellation language file of a reference articulator by reconstructing a file of the participant's skull from CBCT data. In this group, a virtual facebow, prepared by scanning the articulator and facebow complex, was used. After the CM and VM casts had been aligned, the coordinates of target points set on the maxillary right central incisor, maxillary right first molar, and maxillary left first molar were determined, and the mean ±standard deviation distance between the target points was calculated to compare the precision of the techniques. Additionally, vectors of the target point on the maxillary right central incisor were compared to analyze the spatial difference between the techniques. Finally, the occlusal plane angle was calculated. For the correlation analysis of repeated measured data, a 1-way repeated measures analysis of variance (ANOVA) was first performed. The Kolmogorov-Smirnov test was performed to determine normality, and a paired t test and the Wilcoxon signed rank test were performed for normally and nonnormally distributed variables, respectively (α=.05).

RESULTS

The mean distance between target points was significantly greater in the CM group (4.72 ±1.45 to 5.17 ±1.54 mm) than in the VM group (2.14 ±0.58 to 2.35 ±0.60 mm) (P<.05). The standard deviation between target points was significantly greater in the CM group (1.60 ±0.64 to 2.30 ±0.87 mm) than in the VM group (0.74 ±0.23 to 1.12 ±0.45 mm) (P<.05). The maxillary right central incisor was located more anteriorly in the VM group than in the CM (100%, P<.05) group. The occlusal plane angle was significantly steeper in the CM group than in the VM group (8.14 degrees versus 2.13 degrees, P<.05).

CONCLUSIONS

The VM technique was more precise than the CM technique. VM casts were positioned ahead of CM casts. Further, the occlusal plane angle tended to be steeper with the CM technique than with the VM technique.

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.

Four-Dimensional Superimposition Techniques to Compose Dental Dynamic Virtual Patients: A Systematic Review

Four-dimensional virtual patient is a simulation model integrating multiple dynamic data. This study aimed to review the techniques in virtual four-dimensional dental patients. Searches up to November 2022 were performed using the PubMed, Web of Science, and Cochrane Library databases. The studies included were based on the superimposition of two or more digital information types involving at least one dynamic technique. Methodological assessment of the risk of bias was performed according to the Joanna Briggs Institute Critical Appraisal Checklist. Methods, programs, information, registration techniques, applications, outcomes, and limitations of the virtual patients were analyzed. Twenty-seven full texts were reviewed, including 17 case reports, 10 non-randomized controlled experimental studies, 75 patients, and 3 phantoms. Few studies showed a low risk of bias. Dynamic data included real-time jaw motion, simulated jaw position, and dynamic facial information. Three to five types of information were integrated to create virtual patients based on diverse superimposition methods. Thirteen studies showed acceptable dynamic techniques/models/registration accuracy, whereas 14 studies only introduced the feasibility. The superimposition of stomatognathic data from different information collection devices is feasible for creating dynamic virtual patients. Further studies should focus on analyzing the accuracy of four-dimensional virtual patients and developing a comprehensive system.

Facial Scanners in Dentistry: An Overview

Purpose: This narrative review aims to explore the current status of facial scanning technology in the dental field; outlining the history, mechanisms, and current evidence regarding its use and limitations within digital dentistry. Methods: Subtopics within facial scanner technology in dentistry were identified and divided among four reviewers. Electronic searches of the Medline (PubMed) database were performed with the following search terms: facial scanner, dentistry, prosthodontics, virtual patient, sleep apnea, maxillofacial prosthetics, accuracy. For this review only studies or review papers evaluating facial scanning technology for dental or medical applications were included. A total of 44 articles were included. Due to the narrative nature of this review, no formal evidence-based quality assessment was performed and the search was limited to the English language. No further restrictions were applied. Results: The significance, applications, limitations, and future directions of facial scanning technology were reviewed. Specific subtopics include significant history of facial scanner use and development for dentistry, different types and mechanisms used in facial scanning technology, accuracy of scanning technology, use as a diagnostic tool, use in creating a virtual patient, virtual articulation, smile design, diagnosing and treating obstructive sleep apnea, limitations of scanning technology, and future directions with artificial intelligence. Conclusions: Despite limitations in scan quality and software operation, 3D facial scanners are rapid and non-invasive tools that can be utilized in multiple facets of dental care. Facial scanners can serve an invaluable role in the digital workflow by capturing facial records to facilitate interdisciplinary communication, virtual articulation, smile design, and obstructive sleep apnea diagnosis and treatment. Looking into the future, facial scanning technology has promising applications in the fields of craniofacial research, and prosthodontic diagnosis and treatment planning.

Design of wear facets of mandibular first molar crowns by using patient-specific motion with an intraoral scanner: A clinical study

STATEMENT OF PROBLEM

Although computer-aided design has become popular, restorations are typically designed from static occlusion and dynamically by using an average-value virtual articulator. Patient-specific motion recorded by using an intraoral scanner has rarely been used to design restorations, and its design ability has not been analyzed.

PURPOSE

The purpose of this clinical study was to record patient-specific motion by using an intraoral scanner and to analyze its ability to design the morphology of the wear facets on mandibular first molar crowns.

MATERIAL AND METHODS

An intraoral scanner was used to scan complete arch digital casts and to record patient-specific motion of 11 participants. Right and left mandibular first molars were selected as the target teeth. The complete crown preparations of the target teeth were virtually prepared on the digital mandibular casts by using the Geomagic Studio 2013 software program. High points were created by elevating the wear facets of the target teeth by 0.3 mm in the occlusal direction to generate digital wax patterns. The Dental System software program was used to design crowns with the anatomic coping design method. Occlusal adjustment with static occlusion (STA crown), with the average-value virtual articulator (DYN crown), and with patient-specific motion (FUN crown) was carried out. The crowns adjusted with these 3 methods were compared with the original wear facets. The mean value and root mean square (RMS) of 3D deviation were measured. One-way ANOVA was used to analyze the influence of the occlusal surface design methods on the morphology of the wear facets (α=.05).

RESULTS

The STA crowns had the poorest results with the mean ±standard deviation 3D deviation value of 0.15 ±0.05 mm and RMS value of 0.19 ±0.04 mm. The best results occurred in the FUN group, with the mean ±standard deviation 3D deviation value of 0.05 ±0.06 mm and RMS value of 0.13 ±0.03 mm. Significant differences were found among the 3 groups (P<.01). Except for the RMS value between the STA and DYN groups, significant differences were found between groups from the pairwise comparisons.

CONCLUSIONS

The occlusal surface of the crowns designed by using the patient-specific motion recorded with the intraoral scanner had the best coincidence with the morphology of the wear facets on the original teeth.

A Novel Technique to Align the Intraoral Scans to the Virtual Articulator and Set the Patient-Specific Sagittal Condylar Inclination

Customized cast orientations and parameter settings of the virtual articulator according to the patient's condyles are indispensable parts of today's digital workflows in prosthodontics. This article describes a digital technique to align the intraoral scans to a virtual articulator by using a facial scanner to locate the patient's cutaneous landmarks of the arbitrary hinge axis and the reference plane, and to customize the sagittal condylar inclination of the virtual articulator through a digital protrusive interocclusal record and a dental computer-aided design software program. It enables individual cast orientations and virtual articulator parameter settings without conventional facebow transferring and bite registration procedures and can be easily integrated with most virtual articulator systems on the market to allow clinicians and technicians to work in a complete digital workflow and facilitate customized treatment planning and dental prosthesis fabrication.

Esthetic treatment planning with digital animation of the smile dynamics: A technique to create a 4-dimensional virtual patient

A method is presented for obtaining a virtual 4-dimensional patient that replicates the intended esthetic treatment. The process involves facial and intraoral scanning to acquire records and software manipulation to enable a virtual waxing of the smile. Once the digital design is complete, patient information can be merged to generate an animated video of the projected rehabilitation, displaying movement and smile dynamics. This strategy provides a noninvasive and reliable diagnostic tool for predicting clinical outcomes.

Comparison between Occlusal Errors of Single Posterior Crowns Adjusted Using Patient Specific Motion or Conventional Methods

Recently, digital technology has been used in dentistry to enhance accuracy and to reduce operative time. Due to advances in digital technology, the integration of individual mandibular motion into the mapping of the occlusal surface is being attempted. The Patient Specific Motion (PSM) is one such method. However, it is not clear whether the occlusal design that is adjusted using PSM could clinically show reduced occlusal error compared to conventional methods based on static occlusion. In this clinical comparative study including fifteen patients with a single posterior zirconia crown treatment, the occlusal surface after a clinical adjustment was compared to no adjustment (NA; design based on static occlusion), PSM (adjusted using PSM), and adjustment using a semi-adjustable articulator (SA) for the assessment of occlusal error. The root mean square (RMS; μm), average deviation value (±AVG; μm), and proportion inside the tolerance (in Tol; %) were calculated using the entire, subdivided occlusal surface and the out of tolerance area. Using a one-way ANOVA, the RMS and +AVG from the out of tolerance area showed a statistical difference between PSM (202.3 ± 39.8 for RMS, 173.1 ± 31.3 for +AVG) and NA (257.0 ± 73.9 for RMS, 210.9 ± 48.6 for +AVG). For the entire and subdivided occlusal surfaces, there were no significant differences. In the color-coded map analysis, PSM demonstrated a reduced occlusal error compared to NA. In conclusion, adjustment occlusal design using PSM is a simple and effective method for reducing occlusal errors that are difficult to identify in a current computer-aided design (CAD) workflow with static occlusion.

The creation of a virtual dental patient with dynamic occlusion and its application in esthetic dentistry

The application of a virtual dental patient with dynamic occlusion during esthetic restoration in a digital workflow is described. An intraoral scanner, a facial scanner, a jaw motion analyzer, and cone beam computed tomography were used to transfer patient data and construct the virtual dental patient. With the aid of the virtual dental patient, predictability and accuracy can increase throughout treatment, simplifying the clinical evaluation and prosthesis adjustment with improved esthetic outcomes.

Individual mandibular movement registration and reproduction using an optoeletronic jaw movement analyzer and a dedicated robot: a dental technique

BACKGROUND

Fully adjustable articulators and pantographs record and reproduce individual mandibular movements. Although these instruments are accurate, they are operator-dependant and time-consuming. Pantographic recording is affected by inter and intra operator variability in the individuation of clinical reference points and afterwards in reading pantographic recording themselves. Finally only border movements can be reproduced.

METHODS

Bionic Jaw Motion system is based on two components: a jaw movement analyzer and a robotic device that accurately reproduces recorded movements. The jaw movement analyzer uses an optoelectronic motion system technology made of a high frequency filming camera that acquires 140frames per second and a custom designed software that recognizes and determines the relative distance at each point in time of markers with known geometries connected to each jaw. Circumferential modified retainers connect markers and do not cover any occlusal surfaces neither obstruct occlusion. The recording process takes 5 to 10 s. Mandibular movement performance requires six degrees of freedom of movement, 3 rotations and 3 translations. Other robots are based on the so-called delta mechanics that use several parallel effectors to perform desired movements in order to decompose a complex trajectory into multiple more simple linear movements. However, each parallel effector introduces mechanical inter-component tolerances and mathematical transformations that are required to transform a recorded movement into the combination of movements to be performed by each effector. Bionic Jaw Motion Robot works differently, owing to three motors that perform translational movements and three other motors that perform rotations as a gyroscope. This configuration requires less mechanical components thus reducing mechanical tolerances and production costs. Both the jaw movement analyzer and the robot quantify the movement of the mandible as a rigid body with six degrees of freedom. This represents an additional advantage as no mathematical transformation is needed for the robot to reproduce recorded movements.

RESULTS

Based on the described procedure, Bionic Jaw Motion provide accurate recording and reproduction of maxillomandibular relation in static and dynamic conditions.

CONCLUSION

This robotic system represents an important advancement compared to available analogical and digital alternatives both in clinical and research contexts for cost reduction, precision and time saving opportunities.

Effect of increasing occlusal vertical dimension on lower facial form and perceived facial esthetics: A digital evaluation

STATEMENT OF PROBLEM

Increasing occlusal vertical dimension (OVD) is often indicated in complex prosthodontic rehabilitations to gain restorative space and improve the occlusal relationship and esthetics. The effect of increasing occlusal vertical dimension on lower facial height (distance from subnasale to soft-tissue menton) and perceived facial esthetics is not well understood.

PURPOSE

The purpose of this clinical study was to investigate the effect of incremental increases in the occlusal vertical dimension on lower facial height and perceived facial esthetics by using a digital approach.

MATERIAL AND METHODS

Twenty-five participants with Class I jaw relationship and no loss of OVD participated in the study. Custom mandibular devices were digitally designed and 3-dimensionally printed to increase the OVD by 3, 6, and 9 mm in each participant. Three-dimensional facial scans and frontal photographs were made with the participants wearing a specific device to achieve the desired OVD increase. The lower facial height, total facial height (distance between nasion to soft-tissue menton), nasolabial angle, lip width, and lip height were digitally measured on facial scans. All measurements were recorded in a computer-aided design (CAD) software program and were repeated 3 times. Subsequently, frontal photographs of 10 participants were randomly selected for survey. Three groups each of 10 prosthodontists, general dentists, or laypersons participated in the survey and were asked to detect OVD difference in 2 photographs of the same participant and to rank facial esthetics at varying OVDs. One-way repeated measures ANOVA (α=.05) for the facial measurements and descriptive statistics for the survey results were used.

RESULTS

Lower facial height, the ratio of lower facial height to total facial height, lip height, and nasolabial angle increased with an OVD increase, whereas lip width decreased (P<.001). Bonferroni corrected paired t tests revealed all groups of OVD increase to be significantly different from each other (P<.001) except for an OVD increase to 6 mm versus 9 mm in lip height (P=.540) and lip width (P=.019), respectively. Prosthodontists, general dentists, and laypersons could detect a +3 mm OVD increase 63.9%, 62.5%, and 56.5% of the time, respectively. The participants' original OVD was considered the most esthetic (60.0%, 45.0%, and 68.0%) by prosthodontists, general dentists, and laypersons, respectively.

CONCLUSIONS

Increased OVD increases lower facial height, the ratio of lower facial height to total facial height, lip height, and nasolabial angle but decreases lip width. Prosthodontists are more sensitive to a smaller increase in OVD, closely followed by general dentists and then laypersons. In case of no loss of OVD, a vertical increase as small as 3 mm can be detected by both dentists and the general public and perceived as less esthetic. The larger the increase in OVD, the more detectable the difference and the less the faces are perceived as esthetic.