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The purpose of this study was to assess the effect of 3D printing technology (SLA vs. DLP), print orientation (0°, 10°, 20°), and model shell thickness (2 mm vs. 4 mm) on the manufacturing accuracy of full-arch dental casts with teeth preparations. A reference STL file of a maxillary arch, featuring preparations for a posterior crown and a three-unit bridge, was used to fabricate 144 printed models (72 with SLA and 72 with DLP). Each technology group was subdivided based on print orientation (0°, 10°, 20°) and shell thickness (2 mm, 4 mm), resulting in 12 subgroups with n = 12 each. All models were scanned and analyzed for global and landmark-level deviations using surface superimposition (Geomagic Control X). Trueness was calculated via root mean square (RMS) error, and precision was determined as standard deviation (SD). Data were statistically analyzed using the Kruskal–Wallis test to assess trueness, and precision was evaluated using Levene’s median-based test (α = 0.05). Printing technology (DLP vs. SLA), model orientation, and shell thickness showed no significant impact on the overall accuracy, as measured by trueness (RMS: p  = 0.453–1.000) and precision (SD: p  = 0.117). The overall trueness (RMS) values ranged from 73.9 to 194 µm, with all groups remaining below the clinical acceptability threshold (< 0.2 mm). Isolated significant differences were observed at specific anatomical points but did not impact overall model performance. The type of printing technology, orientation angle, and shell thickness did not significantly affect the global accuracy of full-arch models for fixed prosthodontics.

Background This study was carried out as a prospective clinical field study with the aim of evaluating the clinical performance of Equia Fil® with a nanofilled resin coating and the conventional Fuji IX GP® fast with an LC coating according to the World Dental Federation (FDI) restoration material evaluation criteria. Methods The clinical performance of Equia Fil® and Fuji IX GP® fast was evaluated on permanent posterior teeth of 643 adult patients aged between 20 to 80 years old in randomly selected clinics across Germany. Occlusal cavities in posterior permanent teeth were restored with Equia Fil® with a nanofilled, light-cured resin coating ( n  = 515) and Fuji IX GP® fast with an LC coating ( n  = 486). Direct clinical assessment as well as photographic assessment and assessment of stone casts of the restorations were made at 1 year, 2 years, 3 years, and 4 years. Results In 4 years, a total of 1001 fillings from both materials were placed by 111 dentists in 643 patients. Random slope models showed that the Equia filling system had overall lower odds of obtaining a delta event (material needs replacement) in comparison to Fuji IX GP® fast with an LC coating within all models. In both materials, filling size/surface was the most important component affecting the clinical performance of the materials. When measuring the odds of obtaining a delta event (material needs replacement), the odds ratios jumped to approximately 43 and 296 times for class II (two surfaces) and class II mesial-occlusal-distal (three surfaces) respectively in comparison to class I fillings. Conclusion Both materials showed similar good overall performance in class I cavities; however, when including numbers from both class I and II fillings, the Equia system with a nanofilled resin coating showed better overall performance with fewer failures in all the follow-up intervals. Nonetheless, the percentage of unsatisfactory to poor fillings according to the FDI criteria was relatively high in two-surface class II fillings and higher in three-surface class II fillings for both materials. Trial registration Deutsches Register Klinischer Studien (German Clinical Trials Register): DRKS00004220. ( www.germanctr.de ). Registration date: 6 Sept 2012.

Background and Objectives: The ever more complex modern dental education requires permanent adaptation to expanding medical knowledge and new advancements in digital technologies as well as intensification of interdisciplinary collaboration. Our study presents a newly developed computerized method allowing virtual case simulation on modular digital dental models and 3D-printing of the obtained digital models; additionally, undergraduate dental students’ opinion on the advanced method is investigated in this paper. Materials and Methods: Based on the digitalization of didactic dental models, the proposed method generates modular digital dental models that can be easily converted into different types of partial edentulism scenarios, thus allowing the development of a digital library. Three-dimensionally printed simulated dental models can subsequently be manufactured based on the previously obtained digital models. The opinion of a group of undergraduate dental students (n = 205) on the proposed method was assessed via a questionnaire, administered as a Google form, sent via email. Results: The modular digital models allow students to perform repeated virtual simulations of any possible partial edentulism cases, to project 3D virtual treatment plans and to observe the subtle differences between diverse teeth preparations; the resulting 3D-printed models could be used in students’ practical training. The proposed method received positive feedback from the undergraduate students. Conclusions: The advanced method is adequate for dental students’ training, enabling the gradual design of modular digital dental models with partial edentulism, from simple to complex cases, and the hands-on training on corresponding 3D-printed dental models.

Background The evidence on the effect of printing orientation on dimensional accuracy and properties of resinous dental models is unclear. This systematic review aimed to assess the impact of printing orientation on the accuracy and properties of additively manufactured resinous dental models, besides the cost, material consumption, and time efficiency at different orientations. Methods A comprehensive web search (PubMed, Scopus, Cochrane) was performed in July 2024 without language restrictions. The included studies were assessed using the modified consort statement for laboratory studies on dental materials. The outcomes were accuracy and surface quality, besides the cost and time efficiency of additively manufactured dental models printed in different directions. Results Following PRISMA guidelines, 14 records were included. Most records favored horizontally printed models with minor controversies regarding accuracy, material consumption, time, and cost efficiency. While orientation can influence surface quality, it is often more significantly affected by factors such as the printing technology used, the material properties, and the layer thickness. Conclusions Horizontal orientation has proven to be the most efficient for producing dental models, particularly for single-model manufacturing, due to its superior time and cost savings. However, large-scale and overnight massive production favors the vertical orientation since the platform accommodates twice to triple the models' numbers as horizontal orientation. The majority of studies favor horizontal orientation for its accuracy. Choosing the optimal orientation in additive manufacturing not only ensures precision of dental models, improving the fit of restorations and prostheses, but also leads to significant reductions in production time, material usage, and energy consumption, ultimately minimizing environmental impact. Trial registration Not applicable.

The aim of this study was to evaluate and compare the inter-operator reproducibility of three-dimensional (3D) images of teeth captured by a digital impression technique to a conventional impression technique in vivo. Twelve participants with complete natural dentition were included in this study. A digital impression of the mandibular molars of these participants was made by two operators with different levels of clinical experience, 3 or 16 years, using an intra-oral scanner (Lava COS, 3M ESPE). A silicone impression also was made by the same operators using the double mix impression technique (Imprint3, 3M ESPE). Stereolithography (STL) data were directly exported from the Lava COS system, while STL data of a plaster model made from silicone impression were captured by a three-dimensional (3D) laboratory scanner (D810, 3shape). The STL datasets recorded by two different operators were compared using 3D evaluation software and superimposed using the best-fit-algorithm method (least-squares method, PolyWorks, InnovMetric Software) for each impression technique. Inter-operator reproducibility as evaluated by average discrepancies of corresponding 3D data was compared between the two techniques (Wilcoxon signed-rank test). The visual inspection of superimposed datasets revealed that discrepancies between repeated digital impression were smaller than observed with silicone impression. Confirmation was forthcoming from statistical analysis revealing significantly smaller average inter-operator reproducibility using a digital impression technique (0.014± 0.02 mm) than when using a conventional impression technique (0.023 ± 0.01 mm). The results of this in vivo study suggest that inter-operator reproducibility with a digital impression technique may be better than that of a conventional impression technique and is independent of the clinical experience of the operator.

•Introduction of 3D visualisation of PM dental casts in photographic identification.•2D-3D superimposition increased dental match rates with improved accuracy.•3D PM models as an alternate to multiple 2D PM photographs.•The procedure attempted to reduce the limitations of previous 2D methods.•An alternative method in dental identification when using photographs. Photographs of a person smiling may provide valuable information about their anterior dentition. These images can be an alternative ante-mortem (AM) dental source in cases with no dental records, which gives the forensic odontologist a significant opportunity for comparative dental analysis. There are no reported studies that have investigated the reliability of a superimposition technique using 2D photographs of a smile and 3D dental models in dental identification. The aim of this study was to explore novel odontological methods by combining 2D photographs with 3D dental models, simulating a dental identification scenario. The objective was to increase the accuracy of dental identification using an AM photograph with the aid of 3D imaging as an alternative to post-mortem (PM) photographs. The study comprised of 31 3D dental models (simulating PM information) and 35 digital photographs (simulating AM information). The data was analysed in two phases: Phase I- Visual Comparison of 2D-3D images and Phase II- 2D-3D superimposition after a wash out period. Both methods were analysed by the principal investigator. Further, one-third (ten) of the sample was evaluated by six raters (three experienced forensic odontologists and three forensic odontology MSc. students). The inter-rater agreement was assessed using intra-class correlation (ICC 2, 1, absolute). The results of the study suggest that the inter-rater and intra-rater reliability using 3D superimposition was highest (ICC ≈ 1.0). In summary, there was an increase in match rates and higher certainty among the opinions reached when using the 2D-3D superimposition method. The procedure attempted to reduce the limitations of previously existing 2D methods and is intended to assist forensic experts with an alternative method in dental identification when expressing conclusions on a case using photographs.

The utilization of advanced intraoral scanners to acquire 3D dental models has gained significant popularity in the fields of dentistry and orthodontics. Accurate segmentation and labeling of teeth on digitized 3D dental surface models are crucial for computer-aided treatment planning. At the same time, manual labeling of these models is a time-consuming task. Recent advances in geometric deep learning have demonstrated remarkable efficiency in surface segmentation when applied to raw 3D models. However, segmentation of the dental surface remains challenging due to the atypical and diverse appearance of the patients’ teeth. Numerous deep learning methods have been proposed to automate dental surface segmentation. Nevertheless, they still show limitations, particularly in cases where teeth are missing or severely misaligned. To overcome these challenges, we introduce a network operator called dilated edge convolution, which enhances the network’s ability to learn additional, more distant features by expanding its receptive field. This leads to improved segmentation results, particularly in complex and challenging cases. To validate the effectiveness of our proposed method, we performed extensive evaluations on the recently published benchmark data set for dental model segmentation Teeth3DS. We compared our approach with several other state-of-the-art methods using a quantitative and qualitative analysis. Through these evaluations, we demonstrate the superiority of our proposed method, showcasing its ability to outperform existing approaches in dental surface segmentation.

Objective This study was undertaken to evaluate intraoral 3D scans for assessing dental arch relationships and obtain patient/parent perceptions of impressions and intraoral 3D scanning. Materials & Methods Forty-three subjects with nonsyndromic unilateral cleft lip and palate (UCLP) had impressions taken for plaster models. These and the teeth were scanned using the R700 Orthodontic Study Model Scanner and Trios® Digital Impressions Scanner (3Shape A/S, Copenhagen, Denmark) to create indirect and direct digital models. All model formats were scored by three observers on two occasions using the GOSLON and modified Huddart Bodenham (MHB) indices. Participants and parents scored their perceptions of impressions and scanning from 1 (very good) to 5 (very bad). Intra- and interexaminer reliability were tested using GOSLON and MHB data (Cronbach's Alpha >0.9). Bland and Altman plots were created for MHB data, with each model medium (one-sample t tests, P < .05) and questionnaire data (Wilcoxon signed ranks P < .05) tested. Results Intra- and interexaminer reliability (>0.9) were good for all formats with the direct digital models having the lowest interexaminer differences. Participants had higher ratings for scanning comfort (84.8%) than impressions (44.2%) (P < .05) and for scanning time (56.6%) than impressions (51.2%) (P > .05). None disliked scanning, but 16.3% disliked impressions. Data for parents and children positively correlated (P < .05). Conclusions Reliability of scoring dental arch relationships using intraoral 3D scans was superior to indirect digital and to plaster models; Subjects with UCLP preferred intra-oral 3D scanning to dental impressions, mirrored by parents/carers; This study supports the replacement of conventional impressions with intra-oral 3D scans in longitudinal evaluations of the outcomes of cleft care.

Background The purpose of this study was to investigate the trueness of intraoral scanning of residual ridge in edentulous regions during in vitro evaluation of inter-operator validity. Methods Both edentulous maxillary and partially edentulous mandibular models were selected as a simulation model. As reference data, scanning of two models was performed using a dental laboratory scanner (D900, 3Shape A/S). Five dentists used an intraoral scanner (TRIOS 2, 3Shape A/S) five times to capture intraoral scanner data, and the “zig-zag” scanning technique was used. They did not have experience with using intraoral scanners in clinical treatment. The intraoral scanner data was overlapped with the reference data (Dental System, 3Shape A/S). Regarding differences that occurred between the reference and intraoral scanner data, the vertical maximum distance of the difference and the integral value obtained by integrating the total distance were analyzed. Results In terms of the maximum distances of the difference on the maxillary model, the means of five operators were as follows: premolar region, 0.30 mm; molar region, 0.18 mm; and midline region, 0.18 mm. The integral values were as follows: premolar region, 4.17 mm 2 ; molar region, 6.82 mm 2 ; and midline region, 4.70 mm 2 . Significant inter-operator differences were observed with regard to the integral values of the distance in the premolar and midline regions and with regard to the maximum distance in the premolar region, respectively. The maximum distances of the difference in the free end saddles on mandibular model were as follows: right side, 0.05 mm; and left side, 0.08 mm. The areas were as follows: right side, 0.78 mm 2 ; and left side, 1.60 mm 2 . No significant inter-operator differences were observed in either region. Conclusions The present study demonstrated satisfactory trueness of intraoral scanning of the residual ridge in edentulous regions during in vitro evaluation of inter-operator validity.

ABSTRACT Introduction: The purpose of this study was to evaluate the agreement between the predicted and the achieved tooth position planned by an orthodontic digital system. Methods: Digital models of the setup (Predicted) and the treated (Treated) groups of 23 subjects with Class I malocclusion were obtained. Digital models (Predicted and Treated) of each patient were superimposed, and referential geometric planes were constructed for linear and angular measurements: arch perimeter, arch depth, intercanine and intermolar widths, mesiodistal crown angulation, and buccolingual crown inclination. Bland-Altman analysis was performed to establish the agreement between the measurements. Spearman’s correlation coefficient was used to evaluate the correlation between groups. Results: Compared to Predicted group, the Treated group presented larger linear measurements for all measurements: 1) arch perimeter: 1.77±2.10 mm (maxilla) and 1.78±1.74 mm (mandible); 2) arch depth: 0.50±0.69 mm (maxilla) and 0.38±0.81 mm (mandible); 3) intercanine width: 0.30±0.98 mm (maxilla) and 0.49±0.64 mm (mandible), and; 4) intermolar width: 0.70±1.63 mm (maxilla) and 1.13±1.62 mm (mandible). Seven out of 14 angular measurements showed statistical differences between Predicted and Treated groups in the maxilla, while six out of 14 angular measurements were statistically significant between the two groups; the differences ranging from -8.91º to 1.91º and from -3.53° to 9.59° in the maxilla and mandible, respectively. Conclusions: The agreement between the Predicted and Treated groups was majority within the limits. The predictions of the digital system were not accurate in some parameters; however, most of the differences were within clinical acceptable range. Although there are some inaccuracies, the limitations do not seem to interfere with clinical outcomes and the quality of the treatment. RESUMO Objetivo: O objetivo deste estudo foi avaliar a concordância entre a posição dentária preditiva e a obtida, conforme planejado por um sistema ortodôntico digital. Métodos: Foram obtidos modelos digitais dos grupos no setup (Preditivo) e após o tratamento (Tratado) de 23 indivíduos com má oclusão de Classe I. Os modelos digitais (preditivos e tratados) de cada paciente foram sobrepostos, e planos geométricos referenciais foram construídos para obter as seguintes medidas lineares e angulares: perímetro da arcada, profundidade da arcada, distâncias intercaninos e intermolares, angulação mesiodistal da coroa e inclinação vestibulolingual da coroa. A análise de Bland-Altman foi realizada para estabelecer a concordância entre as medidas. O coeficiente de correlação de Spearman foi utilizado para avaliar a correlação entre os grupos. Resultados: Comparado ao grupo Preditivo, o grupo Tratado apresentou medidas lineares maiores para todas as medidas: 1) perímetro da arcada: 1,77±2,10 mm (maxila) e 1,78±1,74 mm (mandíbula); 2) profundidade da arcada: 0,50±0,69 mm (maxila) e 0,38±0,81 mm (mandíbula); 3) distância intercaninos: 0,30±0,98 mm (maxila) e 0,49±0,64 mm (mandíbula); e 4) distância intermolares: 0,70±1,63 mm (maxila) e 1,13±1,62 mm (mandíbula). Entre as quatorze medidas angulares, sete mostraram diferenças estatísticas entre os grupos Preditivo e Tratado na maxila, enquanto seis das quatorze medidas angulares foram estatisticamente significativas entre os dois grupos; as diferenças variaram de -8,91º a 1,91º e de -3,53° a 9,59° na maxila e mandíbula, respectivamente. Conclusões: A concordância entre os grupos Preditivo e Tratado foi majoritariamente dentro dos limites. As previsões do sistema digital não foram precisas em alguns parâmetros; no entanto, em sua maioria as diferenças estavam dentro da faixa clinicamente aceitável. Embora existam algumas imprecisões, as limitações não parecem interferir nos resultados clínicos e na qualidade do tratamento.