The full-contact model has been widely used in tooth preparation and prosthesis fabrication. However, it is rarely used in denture tests. The purpose of the present study was to design a suitable ...full-contact dental model for denture tests.
A standard dental model with the complete tooth morphology was raster scanned and 3D reconstructed. Then, the positioning and fixing surfaces of the dental model were reshaped. The dental model was digitally trimmed into two parts: a fundamental part and a replaceable part. The modular design was presented according to dentition defects around the first molar. The prepared tooth replicas were designed through preparation/scanning/registration/separation sequences. The dental model was fabricated by stereolithography (SLA) 3D-printing rapid prototype technology. The static fracture force of the dental model was predicted using the finite element method. The effects of the four design methods on the suitability of the five testing operations (abutment fabrication, prosthesis fabrication, assembling, loading, and observation) were quantitatively analyzed. The static tests of three fixed partial dentures (FPDs), including tooth-supported, implant-supported, and tooth-tooth-supported prostheses, were conducted to investigate the fracture feature. The dynamic test of a removable partial denture (RPD) was undertaken to study the wear characteristic.
The dental model could bear the maximum fracture strength of 4268.3 N. Seven positive and two negative effects of the design methods were produced. The maximum fracture strength of the FPDs were 1331.2 N, 1356.7 N, and 1987.7 N. The wear facets of the RPD in the dynamic denture test were distributed in three regions.
The force capacity of the full-contact dental model allows the application of static denture tests. The dental model provides improvements in fixture design, removable design, and replica design for the testing operations. The dental model is recommended more in the dynamic test than in the static test.
Objective
Diagnostic casts are one of the standard components of orthodontic records. But they have several drawbacks such as the need for physical space for storage and the risk of breaking due to ...their brittle composition. Today, the digitalization of orthodontic models is a progress in orthodontics. The purpose of this study was to compare and evaluate common orthodontic linear measurements on plaster casts and digital 3D models using Maestro 3D ortho studio® scanner and software (AGE Solutions®, Pontedera, Italy).
Materials and Methods
Study casts of 30 orthodontic patients were selected. Tooth width, space analysis, Bolton analysis, overjet, overbite, and linear measurements of dental arch dimensions were performed by two examiners on plaster casts and digital models.
Statistical Analysis
Intra‐ and interexaminer agreements were evaluated in both manual and digital methods and paired t test was used for evaluating the agreement between the manual and digital measurement. The significance level was set at 0.05.
Results
The intraexaminer agreement was excellent (ICC > 0.75) for most variables in both manual and digital methods. The correlation between the two examiners was significant (p < .05) for most manual and digital measurements. The differences between the manual and digital measurements, although maybe statistically significant, were not clinically significant for most variables.
Conclusion
The use of “Maestro 3D” (AGE Solutions, Pontedera, Italy) scanner and software was acceptable for orthodontic diagnostic measurements instead of study casts.
Given the importance of 3D sensors, a fine-grained analysis on 3D dental model is an important task in computer-aided orthodontic treatment planning. Particularly, the real 3D dental model can ...intuitively show the shape and morphology of the tooth, but due to the irregularity of the 3D tooth data, it poses a challenge for accurate tooth segmentation. In this work, with the mesh data as input, we propose an end-to-end deep neural network, called MBESegNet, for accurate tooth segmentation on 3D dental models. On the one hand, to reduce the ambiguity of the mesh feature representation near the tooth boundary, MBESegNet learns the local context by enhancing the geometric and semantic features with a bidirectional and symmetric structure. On the other hand, MBESeg-Net hierarchically captures the multi-scale contextual features from different scales and represent the feature map following a coarse-to-fine feature fusion strategy for accurate tooth segmentation. The experimental results demonstrate that our approach achieves competitive performance against state-of-the-art 3D shape segmentation methods.
Purpose
This paper aims to obtain a texture dental model with real images and improve the rendering effect of the dental model.
Design/methodology/approach
The paper proposes a semiautomatic method ...to construct a realistic dental model with real images based on two-dimensional/three-dimensional (2D/3D) registration. First, a 3D digital dental model and three intraoral images are obtained by a 3D scanner and digital single-lens reflex camera. Second, the camera projection poses for every intraoral images are calculated by using the single-objective optimization algorithm. Third, with camera poses, the preliminary projection texture mapping is performed; besides, the seam between two textures is marked. Finally, the marked regions are fused based on the image pyramid to eliminate obvious seams.
Findings
The paper provides a method to construct a realistic dental model. The method can map three intraoral images to the dental model. The experimental results show that the textured dental model without obvious distortion, dislocation and seams is constructed with simple interactions.
Originality/value
The proposed method can be applied to the digital smile design system to improve the communication efficiency between doctors, patients and technicians.
In recent years, there has been an increased focus on the teaching of small-animal dentistry to veterinary students in order to address the recognized gap between dental skill training and the ...expectations of employers regarding the competencies of new graduates in this field. In this study, third-year veterinary students were trained in three canine dental core skills using either a high-fidelity model (Group A) or video instruction (Group B). An objective structured clinical examination was used to assess skill acquisition and questionnaires were distributed in order to assess student confidence and perceptions related to small-animal dentistry practice and related skills before and after the training. All results were compared between the two groups. Group A outperformed Group B in skill acquisition (p < 0.001) and there was greater improvement in skill confidence for Group A than Group B (p < 0.001). There was no statistical difference in perceptions related to small-animal dentistry between the two groups after the training (p ≥ 0.1). Group A rated their training experience more highly than Group B (p < 0.001). Although dental skill acquisition shows greater improvement when training is provided by models rather than video instruction, a blended approach to teaching dental skills is likely to be the best approach to optimizing dental skill acquisition.
Objective To provide the experimental basis for the coherence of the indirect bond position by compar⁃ ing the position of the bracket on the digital occlusal model and the position of the transfer ...to the initial plaster model. Methods Fifteen digitized models were selected for the brackets on the dental denture model, the brackets were trans⁃ ferred to the initial plaster model by indirect bond transfer trays, The line distance between each bracket position in dig⁃ ital dental model and initial plaster model was measured with OrthoRx software. Results The difference between the position of the orthodontic brackets and the position of the initial plaster model was less than 0.20 mm, and the differ⁃ ence was statistically significant (P < 0.05). Conclusion The position of the bracket on the digital occlusal model is consistent with that of the original plaster model, which provides a theoretical basis for digital indirect bonding.
3D models are nowadays part of daily clinical practice. Photogrammetry is a brand-new method for transforming small objects into 3D models while keeping their original shape and size. The aim of this ...study was to evaluate the accuracy, in terms of precision and trueness, of a digital dental model acquired with photogrammetry compared with those obtained using extraoral scanners and intraoral scanners, starting from the same plaster model.
A plaster model was converted into a digital model using photogrammetry, an extraoral scanner and an intraoral scanner. Different references were measured twice at a distance of 30 min for each model, on the digital models using the software Blender and on the plaster model using a calibre. The Interclass Correlation Coefficient was calculated for each pair of measurements. A volumetric analysis was performed by superimposing the digital models. The coefficient of variation was calculated. A two-way ANOVA test was conducted.
For each reference, the coefficient of variation was less than 3%, and the two ANOVA tests resulted in a non-significant value in both cases (
> 0.05). The volumetric analysis demonstrated good agreement between the models derived from the different acquisition methods.
Photogrammetry seems to be a good method for acquiring digital models starting from a plaster model, all the methods tested seem to be good for obtaining an accurate three-dimensional digital model. Other studies are needed to evaluate clinical efficacy.
Dentoskeletal changes caused by the long-term use of mandibular advancement devices (MADs) for obstructive sleep apnea (OSA) have rarely been investigated in Japan. We assessed the long-term ...dentofacial morphological changes in 15 Japanese patients with OSA who used two-piece MADs for an average of 4 years. Lateral cephalography analyses were performed initially and 4 years later (T1). The dental assessment included overjet, overbite, upper anterior facial height, lower anterior facial height (LAFH), total anterior facial height (TAFH), and anterior facial height ratio. Dental casts were digitized and analyzed using a 3D scanner. Changes in the apnea hypopnea index (AHI) and other sleep-assessment indices were assessed using polysomnography and out-of-center sleep testing. Radiography revealed lingual inclination of the maxillary central incisors, labial inclination of the mandibular central incisors, clockwise rotation of the mandible, and an increase in the TAFH and LAFH at T1. In the dental cast analysis, the diameter width and palatal depth tended to decrease and increase, respectively. There was a significant decrease in the AHI and other sleep assessment indices after using the MADs for approximately 4 years. However, these findings do not provide a strong basis and should be interpreted cautiously. Future studies should have a larger sample size and should further investigate the long-term occlusal and dental changes caused by the original MADs in Japanese patients with OSA.
Impression making is a critical step in the fabrication of a partial removable dental prosthesis (RDP). A technique is described for making final impressions to fabricate partial RDPs for Kennedy ...class III patients using a computer‐aided design and computer‐assisted manufacturing digital impression system.
PDF
