This study evaluated the accuracy (trueness and precision) of dental models fabricated using additive manufacturing (AM) methods such as PolyJet and fused deposition modeling (FDM).
10 stone models ...were acquired for the control group by scanning a complete arch model. For the experimental groups, 10 PolyJet models and 10 FDM models were fabricated from digital impressions using an intraoral scanner. All 30 models were then scanned, and root mean square values were measured using three-dimensional (3D) analysis software.
Trueness did not significantly differ between the stone and PolyJet models. The precision of the AM models was significantly higher than that of the stone models. The layer thicknesses of the FDM models were greater than those of the PolyJet models.
The results of this study show that it might be possible for the dental models fabricated using additive manufacturing methods to be used in clinical settings.
•We introduce a novel implicit-function-based approach for 3D shape synthesis.•We demonstrate this approach can successfully generate realistic complete dental models from partial inputs.•We validate ...our approach qualitatively and quantitatively by extensive experiments against the state-of-art methods.
While complete dental models are crucial for digital dentistry, current technologies mostly focus on the 3D dental crown but overlook the dental gum that is important for applications in orthodontics and prosthodontics. To reconstruct the complete dental models with visually realistic geometry from the given crown data, we propose to combine the implicit function representation with the self-attention mechanism. Recent studies have shown that the implicit function is an effective 3D representation for shape completion. However, existing methods fail in dealing with dental models with complex shapes and details, because the convolution and linear operations adopted in their networks are inefficient for modeling long-range dependencies or hard to maintain detailed geometry of the shapes. Therefore, we propose to introduce self-attention to the implicit function network for the first time and use it to effectively capture non-local features at different levels. Extensive ablation studies were conducted to validate the efficiency of our method. Quantitative and qualitative comparisons demonstrate that the feature extracted by our network is more expressive and thus leads to better dental model completion and reconstruction results.
Computerized registration between maxillofacial cone-beam computed tomography (CT) images and a scanned dental model is an essential prerequisite for surgical planning for dental implants or ...orthognathic surgery. We propose a novel method that performs fully automatic registration between a cone-beam CT image and an optically scanned model. To build a robust and automatic initial registration method, deep pose regression neural networks are applied in a reduced domain (i.e., two-dimensional image). Subsequently, fine registration is performed using optimal clusters. A majority voting system achieves globally optimal transformations while each cluster attempts to optimize local transformation parameters. The coherency of clusters determines their candidacy for the optimal cluster set. The outlying regions in the iso-surface are effectively removed based on the consensus among the optimal clusters. The accuracy of registration is evaluated based on the Euclidean distance of 10 landmarks on a scanned model, which have been annotated by experts in the field. The experiments show that the registration accuracy of the proposed method, measured based on the landmark distance, outperforms the best performing existing method by 33.09%. In addition to achieving high accuracy, our proposed method neither requires human interactions nor priors (e.g., iso-surface extraction). The primary significance of our study is twofold: 1) the employment of lightweight neural networks, which indicates the applicability of neural networks in extracting pose cues that can be easily obtained and 2) the introduction of an optimal cluster-based registration method that can avoid metal artifacts during the matching procedures.
Removal of impacted supernumerary teeth requires precision and accuracy to prevent iatrogenic injury to important anatomical structures during dental surgery and to improve postoperative healing.
A ...12-year-old girl visited our department for the assessment and management of her deviated front teeth.
Impacted supernumerary tooth extraction in the maxillary anterior region.
The digital guide plate was fabricated after the integration of cone beam computed tomography data with that obtained from scanning the patient's dental model. Impacted supernumerary tooth extraction was performed.
The use of the digital guide plate and planting instruments made the removal of the impacted supernumerary tooth less invasive, faster, and more accurate, whereas the wound was smaller, and the patient experience more comfortable.
Combining the digital guide plate with planting instruments offers a useful aid for the removal of impacted supernumerary teeth among the maxillary anterior region and is, thus, worth promoting.
Three-dimensional tooth segmentation is the segmentation of single-tooth models from a digital dental model. It is an important foundation for diagnosis, planning, treatment and customized appliance ...manufacturing in digital orthodontics. With the deep integration of artificial intelligence technology and big data from stomatology, the use of deep learning algorithms to assist 3D tooth segmentation has gradually become mainstream. This review summarizes the current situation of deep learning algorithms that assist 3D tooth segmentation from the aspects of dataset establishment, algorithm architecture, algorithm performance, innovation and advantages, deficiencies of current research and prospects. The results of the literature review showed that deep learning tooth segmentation methods could obtain an accuracy of more than 95% and had good robustness. However, the segmentation of complex dental models, operation time and richness of the training database still need to be improved. Research and development of t
Objectives
To investigate the anteroposterior and vertical changes of the median rugae area, which is commonly used as dental model superimposition reference, relevant to its underlying skeletal ...structures.
Settings and sample population
Retrospectively collected pre‐ and post‐treatment cephalometric radiographs and 3D digital dental models of 24 orthodontic patients (age at treatment start: 12.26 ± 0.83 years; assessment period: 2.13 ± 0.68 years) were analysed. All had mild to moderate malocclusions that were treated non‐extraction with full fixed appliances.
Material and Methods
The incisive papilla and rugae points were placed on the dental models that were then registered to the cephalometric radiographs. Afterwards, the radiographs were superimposed on Sella, ANS‐PNS, and through a maxillary structural method. The vertical and horizontal movements of the papilla and the rugae points, as well as of a central incisor, were measured (Viewbox 4 software).
Results
The incisive papilla and the three rugae points remained stable anteroposteriorly, but moved downwards in the vertical dimension (approximately 1‐2 mm), in a similar manner (P > .05). However, the anteroposterior position of the papilla and the first rugae points were affected by changes in anterior tooth position and inclination (P < .05).
Conclusion
Both the second and third rugae can be used as superimposition references for tooth movement assessment. The use of the papilla and the first rugae area is not recommended, because they are affected by tooth movement. The outcomes of a palatal superimposition are comparable to those of a maxillary skeletal superimposition in the anteroposterior, but not in the vertical dimension.
The aim of this study was to evaluate the accuracy of dental models fabricated by conventional, milling, and three-dimensional (3D) printing methods. A reference model with inlay, single crown, and ...three-unit fixed dental prostheses (FDP) preparations was prepared. Conventional gypsum models (CON) were manufactured from the conventional method. Digital impressions were obtained by intraoral scanner, which were converted into physical models such as milled gypsum models (MIL), stereolithography (SLA), and digital light processing (DLP) 3D printed photopolymer models (S3P and D3P). Models were extracted as standard triangulated language (STL) data by reference scanner. All STL data were superimposed by 3D analysis software and quantitative and qualitative analysis was performed using root mean square (RMS) values and color difference map. Statistical analyses were performed using the Kruskal–Wallis test and Mann–Whitney U test with Bonferroni’s correction. For full arch, the RMS value of trueness and precision in CON was significantly smaller than in the other groups (p < 0.05/6 = 0.008), and there was no significant difference between S3P and D3P (p > 0.05/6 = 0.008). On the other hand, the RMS value of trueness in CON was significantly smaller than in the other groups for all prepared teeth (p < 0.05/6 = 0.008), and there was no significant difference between MIL and S3P (p > 0.05/6 = 0.008). In conclusion, conventional gypsum models showed better accuracy than digitally milled and 3D printed models.
Background and aim: Good dentofacial growth is a major goal in the treatment of unilateral cleft lip and palate (UCLP). The aim was to evaluate dental arch relationships at age 5 years after four ...different protocols of primary surgery for UCLP.
Design: Three parallel randomised clinical trials were undertaken as an international multi-centre study by 10 cleft teams in five countries: Denmark, Finland, Sweden, Norway, and the UK.
Methods: Three different surgical procedures for primary palatal repair (Arms B, C, D) were tested against a common procedure (Arm A) in the total cohort of 448 children born with non-syndromic UCLP. Study models of 418 patients (273 boys) at the mean age of 5.1 years (range = 4.8-7.0) were available. Dental arch relationships were assessed using the 5-year index by a blinded panel of 16 orthodontists. Kappa statistics were calculated to assess reliability. The trials were tested statistically with t- and Chi-square tests.
Results: Good-to-very good levels of intra- and interrater reliability were obtained (0.71-0.94 and 0.70-0.87). Comparisons within each trial showed no statistically significant differences in the mean 5-year index scores or their distributions between the common method and the local team protocol. The mean index scores varied from 2.52 (Trial 2, Arm C) to 2.94 (Trial 3, Arm D).
Conclusion: The results of the three trials do not provide statistical evidence that one technique is better than the others. Further analysis of the possible influence of individual surgical skill and learning curve are being pursued in this dataset.
Trial registration: ISRCTN29932826.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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