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

Accuracy of a new photometric jaw tracking system in the frontal plane at different recording distances: An in-vitro study

OBJECTIVES

To evaluate the accuracy of a new photometric jaw tracking system (JTS) in recording linear vertical movements in the frontal plane at different distances.

METHODS

A mandibular plaster cast of a patient was placed on a simulation machine capable of linear movements along two spatial axes. Cyclops JTS (Itaka) was adapted to the plaster cast, while the head frame was attached to the simulation machine. The latter performed five linear movements from 20 to 40 mm in the y-axis; each movement was repeated five times at five different recording distance (380 to 420 mm). The recorded movements were measured and compared with those obtained with a laser Doppler vibrometer (LDV) for accuracy analysis. Data were statistically processed (α = 0.05).

RESULTS

No statistically significant differences were found between Cyclops and LDV measurements on the y- and z-axes (p = 0.5). Changes in linear vertical motion and distance positions did not affect the accuracy, which remained relatively constant with similar trends and values less than 1 % for each parameter variation. The best condition observed was linear vertical movement of 30 mm at 420 mm (0.010 ± 0.023 mm).

CONCLUSIONS

Cyclops has proven to be an accurate JTS in recording linear vertical movements in the frontal plane at different recording distances. For optimal recordings, the scanner should be placed as close as possible to the markers; excessive vertical movements decreased the accuracy. However, this study has limitations and requires in-vivo confirmations.

CLINICAL SIGNIFICANCE

The tested JTS proved accurate in recording linear vertical movements in the frontal plane. However, given the limitations of the study, further investigation under real conditions is needed to support prosthetic and gnathological rehabilitations.

Sagittal condylar guidance angle measurement methods: A systematic review

STATEMENT OF PROBLEM

Precise assessment of the condylar guidance angle can aid successful prosthodontic treatment. However, the reliability and accuracy of current methods remain unclear.

PURPOSE

The purpose of this systematic review was to evaluate the reliability and accuracy of current methods of determining the sagittal condylar guidance angle, including protrusive interocclusal records, axiography, cone beam computed tomography (CBCT), and panoramic and cephalometric radiographs.

MATERIAL AND METHODS

A literature search was conducted using BASE, Embase, PubMed, and Web of Science databases up to June 2022. Inclusion criteria involved studies that compared protrusive interocclusal records against other methods of sagittal condylar guidance angle assessment in adult dentate and edentulous patients. Studies that did not provide the values for the right and left joint separately were excluded. The methodological quality of the included studies was assessed by using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Data were tabulated and analyzed for correlations and their significance.

RESULTS

A total of 24 articles qualified for the analysis. The differences between protrusive interocclusal records and panoramic radiograph sagittal condylar guidance angle values were up to 9 degrees. Lateral cephalometric radiographs revealed greater condylar guidance values than facebow transfers or the Bonwill methods. Correlations between average sagittal condylar guidance angle values obtained from CBCT and protrusive interocclusal records differed depending on the method of registration. For protrusive interocclusal records, axiographic or pantographic measurement variance analysis showed that the condylar inclination values recorded with wax were statistically lower than those recorded with a pantograph (P<.05).

CONCLUSIONS

Although CBCT appears to be the most suitable method of evaluating the sagittal condylar guidance angle, the limitations and discrepancies among methods, including protrusive interocclusal records and panoramic and cephalometric radiographs, should be acknowledged. Digital axiography, with its potential to capture comprehensive functional data, may surpass other techniques. The use of mean values for articulators may be a practical solution for some patients. Further research is needed to refine sagittal condylar guidance angle assessment methods and to develop more reproducible and reliable approaches for the future.

Investigation of the precision of a novel jaw tracking system in recording mandibular movements: A preliminary clinical study

OBJECTIVES

This preliminary study aimed to clinically assess the precision of a novel optical jaw tracking system (JTS) in registering mandibular movements (MMs) of protrusion and mediotrusion.

METHODS

Twenty healthy participants underwent recordings using Cyclops JTS (Itaka Way Med) for functional MMs of protrusion and laterotrusion by two trained clinicians. Each subject performed five registrations at different times according to a standardized pattern within one-month period. The angulations of protrusive and mediotrusive functional paths within the first 2 mm from the maximal intercuspal position (MIP) were calculated for each trace, using a data software for angle measurements. Descriptive statistics were used to assess the repeatability of the recordings for each participant and MM. Additionally, inferential statistics were carried out on standard deviation values obtained (α=0.05).

RESULTS

The overall precision for all the patients was 7.07±3.37° for the protrusion angle, 5.24±2.24° for right laterotrusion and 5.14±3.06° for left laterotrusion angles. The protrusion angle ranged from 3.08° to 13.57°, while the right and left laterotrusion ranged from 1.82° to 9.42° and from 1.58° to 10.59°, respectively. No statistically significant differences were observed between different functional MM types and gender (p > 0.05).

CONCLUSIONS

Recordings functional MMs of mediotrusion and protrusion using Cyclops JTS showed consistent repeatability, regardless of gender and functional MM type. The results revealed non-negligible variations that may be due to the patients' abilities to precisely reproduce jaw movements or to the operator's ability to consistently connect the kinesiograph.

CLINICAL SIGNIFICANCE

Capturing functional MMs digitally and importing the data into dental CAD software is essential for virtual waxing in prosthetic rehabilitations to design a functionalized adapted occlusion. Establishing the repeatability of MM recordings by a JTS is a crucial step in better understanding this novel JTS in the market. This process could facilitate the interpretation of cusp angles, aid in CAD dynamic technical modeling, and enhance clinical data communication between clinicians and technicians in a modern workflow.

Generative deep learning approaches for the design of dental restorations: A narrative review

OBJECTIVES

This study aims to explore and discuss recent advancements in tooth reconstruction utilizing deep learning (DL) techniques. A review on new DL methodologies in partial and full tooth reconstruction is conducted.

DATA/SOURCES

PubMed, Google Scholar, and IEEE Xplore databases were searched for articles from 2003 to 2023.

STUDY SELECTION

The review includes 9 articles published from 2018 to 2023. The selected articles showcase novel DL approaches for tooth reconstruction, while those concentrating solely on the application or review of DL methods are excluded. The review shows that data is acquired via intraoral scans or laboratory scans of dental plaster models. Common data representations are depth maps, point clouds, and voxelized point clouds. Reconstructions focus on single teeth, using data from adjacent teeth or the entire jaw. Some articles include antagonist teeth data and features like occlusal grooves and gap distance. Primary network architectures include Generative Adversarial Networks (GANs) and Transformers. Compared to conventional digital methods, DL-based tooth reconstruction reports error rates approximately two times lower.

CONCLUSIONS

Generative DL models analyze dental datasets to reconstruct missing teeth by extracting insights into patterns and structures. Through specialized application, these models reconstruct morphologically and functionally sound dental structures, leveraging information from the existing teeth. The reported advancements facilitate the feasibility of DL-based dental crown reconstruction. Beyond GANs and Transformers with point clouds or voxels, recent studies indicate promising outcomes with diffusion-based architectures and innovative data representations like wavelets for 3D shape completion and inference problems.

CLINICAL SIGNIFICANCE

Generative network architectures employed in the analysis and reconstruction of dental structures demonstrate notable proficiency. The enhanced accuracy and efficiency of DL-based frameworks hold the potential to enhance clinical outcomes and increase patient satisfaction. The reduced reconstruction times and diminished requirement for manual intervention may lead to cost savings and improved accessibility of dental services.

Investigation of the accuracy of dynamic condylar position: A model study

OBJECTIVES

To evaluate dynamic condylar positions by integrating mandibular movement recording data and cone-beam computed tomography (CBCT) and to investigate its accuracy via dynamic model experiments.

METHODS

A polyvinyl chloride skull model was utilized. A robot arm was used to operate the mandible to perform mouth opening, closing, protrusion, and lateral movements. A recording device, worn on the skull, was used to record the dynamic process and an optical position tracking (OPT) system was used to simultaneously trace the movements. A self-developed software module was used to evaluate the dynamic condylar position by integrating the dynamic tracing data and a virtual skull model derived from CBCT images. Errors were defined as differences between the dynamic coordinates of six landmarks around the condylar area derived from the software module (test) and OPT system (gold standard).

RESULTS

The condylar position errors were 0.76 ± 0.31, 0.55 ± 0.15, and 0.68 ± 0.23 mm for mouth opening, bilateral, and protrusion movements, respectively. Furthermore, the errors for small, moderate, and large mouth opening movements were 0.62 ± 0.19, 0.69 ± 0.29, and 0.94 ± 0.31 mm, respectively. The errors for all movements, except for large mouth opening, were significantly less than 1 mm (P < 0.05). The error was not different from 1 mm in the large mouth opening movement (P > 0.05).

CONCLUSIONS

Our developed method of achieving dynamic condylar position by integrating mandibular movement recording data and CBCT images is clinically reliable.

CLINICAL SIGNIFICANCE

This study proved the reliability of evaluating dynamic condylar position using a commercial dynamic recording instrument and CBCT images.

Comparison between Bone-Level and Tissue-Level Implants in Immediate-Loading Full-Arch Rehabilitations: A Retrospective Multi-Center 1-Year Follow-Up Study

The objective of the present retrospective multi-center study was to analyze the outcomes of bone-level (BL) implants and tissue-level (TL) implants in immediate-loading full-arch rehabilitations. Patients who were previously rehabilitated with full-arch immediate-loading rehabilitations with either BL or TL implants were considered. Data regarding implant survival rate, marginal bone loss (MBL), peri-implant probing depth (PPD), plaque index (PI), and bleeding on probing (BOP) were recorded, and the 1-year follow-up data were statistically analyzed between the two groups. In total, 38 patients were evaluated for a total implant number of 156 (n = 80 TL implants and n = 76 BL implants). An implant survival rate of 97.37% was recoded for the BL group while an implant survival rate of 100% was noted for the TL group. A total MBL of 1.324 ± 0.64 mm was recorded for BL implants, while a total MBL of 1.194 ± 0.30 mm was recorded for TL implants. A statistically significant difference was highlighted regarding MBL at the mesial aspect (p = 0.01552) of the implants, with BL implants presenting with higher MBL. Within the range of acceptable healthy values, a statistically significant difference was also highlighted regarding BOP (p < 0.00001), with TL implants presenting higher values. No statistically significant difference (p > 0.05) was recorded for any of the other variables analyzed. Within the limitations of the present retrospective study, both TL and BL implants seem to provide good clinical outcomes after a 12-month observational period when employed in immediate-loading full-arch rehabilitation.

Factors influencing the efficacy of invisalign in molar distalization and tooth movement

Introduction: The work aims to establish and analyze the factors influencing the efficacy of Invisalign in molar distalization and tooth movement. Objectives of the study: 1) identify factors contributing to molar distalization and tooth movement; 2) analyze the effectiveness of Invisalign technology in molar distalization and tooth movement. Methods: The study was conducted in 2020-2022 in Baoding (PRC) based on Baoding's first central hospital. Forty patients (mean age 28.5 ± 1.5 years, 18-35 years; 20 women and 20 men) participated in the study. Results: All patients had mild to moderate degrees of tooth crowding, with an angle class II malocclusion, as well as maxillary third molars. Before and after the therapy, the condition of the alveolar bone, soft tissues, and facial height were measured. Fixation of the anterior teeth was performed. Calculations of the distal molar movement were performed. For orthodontic procedures, the second M of the upper jaw were moved, and then the first molars were moved. Discussion: Distalization of the upper molars was found to be an effective movement, with an efficiency of about 83% when vertical rectangular attachments were used. The first molar was moved distally by 2.85 mm without significant tilt or movement in the vertical plane.