Objective:To develop an efficient and robust method based on three dimensional facial landmarks for evaluating chin region asymmetry at the soft tissue level and to compare it with the tradi-tional mirror-overlap analysis method in order to test its availability.Methods:Standard symmetrical face was used for mental tubercle coordinate transformation so as to filter soft tissue three dimensional spatial angle and construct corresponding three dimensional spatial angle wireframe template.Ten patients aged 12-32 years with clinical chin region asymmetry diagnosis at the Department of Orthodontics of Peking University Hospital of Stomatology from November 2020 to November 2021 were randomly selected.Three dimensional soft tissue face scan data of the patients were collected by three dimensional face scanner and the landmark points were automatically determined by the Meshmonk non-rigid registration algorithm pro-gram,and in this way,the asymmetric three dimensional spatial angle wireframe template and corre-sponding spatial angle parameters were generated.Mirror-overlap analysis of face scan data was also per-formed in Geomagic Studio 2015 software and deviation color maps were generated.This study took mirror-overlap analysis as the gold standard method,the response rate of chin region asymmetry was eva-luated by the outcomes of the mirror-overlap analysis and three dimensional spatial angle wireframe tem-plate analysis.Results:Nine three dimensional spatial angle indicators were selected through coordinate transformation,and the response rate was calculated using mirror-overlap analysis as the gold standard method.Among these ten selected patients,the response rate of the total chin region asymmetry was 90％(9/10).Using the deviation value of mirror-overlap analysis as a reference,the response rate of chin region asymmetry in the X dimension was 86％,the response rate of chin region asymmetry in the Y dimension was 89％,and the response rate of chin region asymmetry in the Z dimension was 100％.Conclusion:The three dimensional soft tissue spatial angle wireframe template proposed in this study has some feasibility in evaluating chin region asymmetry at the soft tissue level,and its ability to recognize asymmetry separately in the three dimensional direction is better than the mirror-overlap analysis method,and the indicators recognition rate still needs to be further improved.

In the field of dental aesthetics,digital aesthetic design plays a crucial role in helping dentists to predict treatment outcomes vis-ually,as well as in enhancing the consistency of knowledge and understanding of aesthetic goals between dentists and patients.It serves as the foundation for achieving ideal aesthetic effects.However,there is no clear standard for this digital process currently in China and abroad.Many dentists lack of systematic understanding of how to carry out digital aesthetic design for treatment.To establish standardized processes for dental aesthetic design and to improve the homogeneity of treatment outcomes,Chinese Society of Digital Dental Industry(CSD-DI)convened domestic experts in related field to compile this consensus.This article elaborates on the key aspects of digital aesthetic data collection,integration steps,and the digital aesthetic design process.It also formulates a decision tree for dental aesthetics at macro level and outlines corresponding workflows for various clinical scenarios,serving as a reference for clinicians.

Pediatric dentistry treats patients aged 0-18 years, encompassing the characteristics of general dentistry. The clinical techniques are closely related to restorative dentistry, endodontics, orthodontics, and maxillofacial surgery, while also possessing unique aspects. It particularly focuses on the growth and development patterns of children′s dentition and maxillofacial structures. Currently, digital technology has deeply integrated with various clinical disciplines of dentistry, and pediatric dentistry has made significant progress with pediatric-specific digital applications. On one hand, the introduction of mature digital technologies is enabling the digital transformation of pediatric dental treatment models; on the other hand, there is innovative development of new digital technologies tailored to the specific needs of pediatric dental care, filling gaps in the field. Based on years of research in digital technology for pediatric dentistry, our team details the current innovative applications and scientific explorations in this area from these two perspectives. Additionally, we anticipate the potential expansion of digital technologies not yet applied in pediatric dentistry, providing a reference for clinical scholars in the field to conduct exploratory research.

Objective:To explore the digital design and fabrication technology of personalized restorative matrix for dental filling, and to explore the feasibility of direct resin restoration for deep caries lesions in distal neck of mandibular second molar.Methods:For patients with deep caries lesions in the distal neck of the mandibular second molar who visited the Department of Cariology and Endodontology of Peking University School and Hospital of Stomatology from September 2023 to April 2024, after preparing the cavity and gingival retractor, a three-dimensional intraoral scanner was used to obtain three-dimensional data of the patient′s dentition. In the dental restoration computer-aided design software, the inlay function was used to generate the restored tooth morphology. The edge range of the personalized restorative matrix was drawn on the restored model by three-dimensional reverse engineering software to achieve edge sealing effect. The selected edge range data was processed with distal shelling to generate a digital model of a personalized restorative matrix with a thickness of 0.5 mm. A metal three-dimensional printer was used to fabricate the titanium alloy restorative matrix, and its application was completed in 10 clinical cases. The marginal adaptation and retention stability of the personalized restorative matrix were evaluated under a dental microscope, and forming effect evaluation was performed through immediate postoperative periapical radiographs.Results:The preliminary clinical application of the personalized restorative matrix fabricated using digital technology revealed that, in the treatment of 10 affected teeth, rubber dam isolation was successfully ensured, resulting in clinically effective direct resin composite restorations with optimal marginal adaptation and reasonable contours. Immediate postoperative periapical radiographs showed good convexity of the filling body, with no overhangs found. Both marginal adaptation and retention stability met the requirements of clinical treatment.Conclusions:The personalized restorative matrix designed in this study can solve the clinical problems of moisture separation and resin forming in the treatment of deep caries lesions in distal neck of the mandibular second molar, and can achieve stable and reliable adhesive restoration effects.

Objective:To explore the method of obtaining the key parameters of the average value articulator in healthy people based on mandibular movement trajectory data, with a view to providing a reference for the clinical application of the average value articulator.Methods:One hundred healthy volunteers (42 males and 58 females) with individual normal occlusion, aged 18-55 years old, who met the inclusion criteria were recruited from Beijing, and their mandibular movement trajectory data were collected. The left and right sagittal condylar inclination(SCI) and transversal condylar inclination(TCI) were obtained from the values of the articulator parameters which were generated in the mandibular movement analysis system.The SCI and TCI were grouped by gender and calculated separately for the two groups and the overall sample; the gender differences in the two parameters and the differences between the mean values of the two parameters and the average value articulator empirical values (35° for SCI and 15° for TCI) for the overall sample were compared.Results:The differences between SCI (35.8°±7.4°) and TCI [11.2° (11.3°)] in males and the corresponding parameters [35.6°±8.3° and 10.8° (9.5°), respectively] in females were not statistically significant ( t=0.10, P=0.922; Z=-0.60, P=0.552); the overall sample SCI (35.7°±7.9°) did not differ statistically from the average value articulator empirical value ( t=1.23, P=0.221), and the overall sample TCI [10.9° (10.3°)] was significantly smaller than the average value articulator empirical value ( W=5 825.00, P<0.001). Conclusions:The mandibular movement trajectory data of 100 adults with individual normal occlusion in this study shows that the gender factor does not affect the setting of the key parameters of the average value articulator, the SCI of the average value articulator empirical values is appropriate, and the TCI has the possibility of being on the large side. In the clinical use of the articulator to assist in the design of restorations, the parameter values should be rationally adjusted according to the actual situation of the patient′s dentition and mandibular movement.

Objective:To explore the impact of digital technology in constructing a three-dimensional (3D) symmetry reference plane (SRP) for esthetic restoration of anterior teeth and to evaluate its clinical applicability.Methods:A cross-sectional study was conducted from February to May 2024, involving 20 patients [11 males and 9 females, aged (36.8±11.4) years] who underwent anterior esthetic restorations at the Department of Stomatology, People′s Hospital of Ningxia Hui Autonomous Region. Symmetrical reference planes of patients′ 3D facial models were constructed using three different algorithms: weighted Procrustes analysis (WPA), Procrustes analysis (PA) based on the ontology-mirror correlation method, and iterative closest point (ICP). The SRP defined by an associate chief physician served as the control (true-value group). The angular errors between each algorithm group and the true-value group were compared. The optimal algorithm was selected and combined with a three-dimensional digital smile design (DSD) to create virtual patients, followed by designing anterior restorations. The visual analogue scale (VAS) was used by patients to score the aesthetic restoration results of the conventional design (control group) and the algorithm-based design (algorithm group).Results:The angular errors of the WPA, PA, and ICP groups were 1.43°±0.66°, 1.82°±0.88°, and 4.74°±2.03° respectively, with statistically significant differences among the groups ( F=41.10, P<0.001). Pairwise comparisons showed that the WPA group had significantly smaller angular errors compared to the PA and ICP groups ( P<0.05). The VAS scores for aesthetic restoration were significantly higher in the algorithm group (8.09±0.74) compared to the control group (6.30±1.38) ( t=-5.49, P<0.001). Conclusions:The SRP constructed using the WPA algorithm demonstrated minimal angular error when compared to the expert-defined SRP and is considered the optimal choice in clinical practice, yielding high patient satisfaction.

Objective To explore the characteristics and correlation of the chin and airway in females with skeletal Class Ⅱ mandibular retraction for reference for clinical diagnosis and therapy.Methods This study was approved by the hospital Medical Ethics Committee.Forty cases of skeletal Class Ⅱ mandibular retraction adult females with aver-age angle were selected as the research group,and sixty cases of skeletal Class Ⅰ patients with average angle were se-lected as the control group.Cone-beam computed tomography(CBCT)images for all subjects were analyzed using three-dimensional modeling software.Measurements included the chin morphology,position,and upper airway morphology.Results Compared with skeletal Class Ⅰ patients,patients with skeletal Class Ⅱ mandibular retraction had smaller an-terior chin thickness,base bone volume,chin total volume,and larger chin angle,chin depression,chin curvature,and alveolar area with statistically significant differences(P＜0.05).Gn-V,Gn-H,Po-NB distance,and facial angle were smaller,and the Y-axis angle was larger in patients with skeletal Class Ⅱ mandibular retraction with statistically signifi-cant differences(P＜0.05).Upper airway total volume,transverse and sagittal diameter of the glossopharynx upper boundary were smaller in patients with skeletal Class Ⅱ mandibular retraction with statistically significant differences(P＜0.05).The correlation analysis between the morphology and position of the chin and the morphology of the upper airway in patients with Class Ⅱ mandibular retraction showed that there was a negative correlation between chin angle and laryngopharynx length in patients with Class Ⅱ mandibular retraction(r=-0.277,P＜0.01).There was a negative correlation between Po-NB distance and palatopharyngeal length(r=-0.222,P＜0.05).Chin height(r=-0.261,P＜0.01)and basal bone area(r=-0.225,P＜0.05)were negatively correlated with the transverse diameter of the palato-pharyngeal upper boundary.The minimum chin thickness(r=0.245,P＜0.05),chin angle(r=0.249,P＜0.05),and al-veolar area(r=0.213,P＜0.05)were positively correlated with the sagittal diameter of the palatopharyngeal upper boundary.Gn-V(r=0.217,P＜0.05)and Po-NB distance(r=0.208,P＜0.05)were positively correlated with the trans-verse diameter of the glossopharynx upper boundary.Anterior chin thickness was negatively correlated with the sagittal diameter of the laryngopharynx upper boundary(r=-0.211,P＜0.05).Chin depression was negatively correlated with the sagittal diameter of the laryngopharynx lower boundary(r=-0.237,P＜0.05).Chin curvature was positively corre-lated with the transverse diameter of the laryngopharynx lower boundary(r=0.231,P＜0.05).Conclusion Patients with skeletal Class Ⅱ mandibular retraction exhibit thinner chins.The sagittal position of the chin is backward,and the vertical position is upward.Patients with skeletal Class Ⅱ mandibular retraction have a narrow glossopharyngeal airway.There is a correlation between the morphology and position of the chin and the morphology of the upper airway in pa-tients with Class Ⅱ mandibular retraction.

Objective This study proposes a chairside digital design and manufacturing method for band and loop space maintainers and preliminarily validates its clinical feasibility.Methods Clinical cases of 10 children requiring space maintenance caused by premature loss of primary teeth were collected.Intraoral scan data of the affected children were also collected to establish digital models of the missing teeth.Using a pediatric band and loop space maintainer de-sign software developed by our research team,a rapid personalized design of band and loop structures was achieved,and a digital model of an integrated band and loop space maintainer was ultimately generated.A chairside space maintainer was manufactured through metal computer numerical control machining for the experimental group,whereas metal 3D printing in the dental laboratory was used for the control group.A model fitting assessment was conducted for the space maintainers of both groups,and senior pediatric dental experts were invited to evaluate the clinical feasibility of the space maintainers with regard to fit and stability using the visual analogue scale scoring system.Statistical analysis was also performed.Results The time spent in designing and manufacturing the 10 space maintainers of the experimental group was all less than 1 h.Statistical analysis of expert ratings showed that the experimental group outperformed the control group with regard to fit and stability.Both types of space maintainers met clinical requirements.Conclusion The chairside digital design and manufacturing method for pediatric band and loop space maintainers proposed in this study can achieve same-day fitting of space maintainers at the first appointment,demonstrating good clinical feasibility and significant potential for clinical application.

Objective To investigate the biomechanical effects of lingual metal-reinforced denture bases on edentulous implant-supported prostheses by three-dimensional finite element analysis,and provide references for the treatment of edentulous jaws.Methods Two implant-supported Locator-type overdenture models with lingual metal-reinforced and non-reinforced denture bases were constructed.A 150 N vertical load on the fovea of the posterior teeth,a 150 N oblique load on the fovea of the posterior teeth,and a 150 N vertical load on the anterior teeth were applied to simulate the centric occlusion,left and right lateral chewing,and anterior teeth cutting,and stresses on the tissues of two models were analyzed.Results When the posterior and anterior teeth were loaded vertically,the stress distribution on each organization was similar between the two denture base designs.The maximum stress difference was between 0 and 0.16 MPa.Under unilateral masticatory chewing,the range of stress concentration on denture base,implant and mucoperiosteum,and the maximum stress of the implant and peri-implant bone without metal reinforcement were significantly greater than those with metal reinforcement,and the maximum stress difference was between 0.59 MPa and 2.99 MPa.Conclusions Lingual metal-reinforced denture base can play a role in stress dispersion,or reduce the risk of bone resorption and denture base fracture to a certain extent.

Objective: To develop a method for generating three-dimensional (3D) digital models of the periodontal ligament (PDL) using 3D cone-beam computed tomography (CBCT) reconstruction and to evaluate the accuracy and agreement of the 3D PDL models in the measurement of periodontal bone loss. Methods: CBCT data collected from four patients with skeletal Class III malocclusion prior to periodontal surgery were reconstructed at three voxel sizes (0.2 mm, 0.25 mm, and 0.3 mm), and 3D tooth and alveolar bone models were generated to obtain digital PDL models for the maxillary and mandibular anterior teeth. Linear measurements of the alveolar bone crest obtained during periodontal surgery were compared with the digital measurements for assessment of the accuracy of the digital models. The agreement and reliability of the digital PDL models were analyzed using intra- and interexaminer correlation coefficients and Bland–Altman plots. Results: Digital models of the maxillary and mandibular anterior teeth, PDL, and alveolar bone of the four patients were successfully established. Relative to the intraoperative measurements, linear measurements obtained from the 3D digital models were accurate, and there were no significant differences among different voxel sizes at different sites. High diagnostic coincidence rates were found for the maxillary anterior teeth. The digital models showed high intra- and interexaminer agreement. Conclusions Digital PDL models generated by 3D CBCT reconstruction can provide accurate and useful information regarding the alveolar crest morphology and facilitate reproducible measurements. This could assist clinicians in the evaluation of periodontal prognosis and establishment of an appropriate orthodontic treatment plan.