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The International Journal of... Feb 2024To evaluate and compare the fracture resistance and elastic modulus of 3D-printed post and core systems and fiber posts and composite cores.
PURPOSE
To evaluate and compare the fracture resistance and elastic modulus of 3D-printed post and core systems and fiber posts and composite cores.
MATERIALS AND METHODS
Endodontic treatment was performed on 30 mandibular premolars, and post space preparation was performed. The teeth were then randomly divided into two groups (n = 15 per group): the 3D-printed (3DP) group and the fiber post and composite core (FPC) group. In the FPC group, fiber posts (Cytec Blanco 43.604, Hahnenkratt) were bonded with resin cement (RelyX U200, 3M), and the composite core dimension was standardized with a silicone index. In the 3DP group, the impression of the post space for each specimen was taken with pattern resin (Pattern Resin, GC America), and the coronal core was produced with the same silicone index. The impressions of the posts and cores were scanned, and then the custom post and core structures were fabricated from permanent crown resin material (Permanent Crown Resin, Formlabs) with a 3D printer (Form3B, Formlabs). Specimens were subjected to load tests with a universal testing machine (M500-25AT, Testometric). After fracture occurred, the fracture force and elastic modulus were calculated. The data were analyzed by independent sample t test (α = .05) Results: There was no statistically significant difference between the two groups in terms of peak fracture force (P = .626) and elastic modulus (P = .125), and no catastrophic root fractures were observed in either group.
CONCLUSIONS
The fracture resistance of endodontically treated teeth was not significantly influenced by the post material. 3D-printed, custom-made resin posts were as effective as fiber glass posts with regard to fracture resistance.
Topics: Humans; Composite Resins; Post and Core Technique; Crowns; Glass; Resin Cements; Silicones; Printing, Three-Dimensional; Tooth Fractures; Tooth, Nonvital; Dental Stress Analysis
PubMed: 38498864
DOI: 10.11607/ijp.8860 -
The International Journal of... Feb 2024To evaluate the effect of model resin type and time interval on the dimensional stability of additively manufactured diagnostic casts.
PURPOSE
To evaluate the effect of model resin type and time interval on the dimensional stability of additively manufactured diagnostic casts.
MATERIALS AND METHODS
Ten irreversible hydrocolloid impressions and 10 impressions from an intraoral scanner were made from a reference maxillary stone cast, which was also digitized with a laboratory scanner. Conventional impressions were poured in type III stone (SC), while digital impressions were used to additively manufacture casts with a nanographene-reinforced model resin (GP) or a model resin (DM). All casts were digitized with the same laboratory scanner 1 day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Cast scans were superimposed over the reference cast scan to evaluate dimensional stability. Data were analyzed with Bonferroni-corrected repeated measures ANOVA (α = .05).
RESULTS
The interaction between the main factors (material type and time interval) affected anterior teeth deviations, while the individual main factors affected anterior teeth and entire-cast deviations (P ≤ .008). Within anterior teeth, DM had the lowest deviations at T3, and GP mostly had lower values at T2 and lower deviations at T3 than at T0 (P ≤ .041). SC had the highest pooled anterior teeth deviations, and GP had the highest pooled entire cast deviations (P < .001). T3 had lower pooled anterior teeth deviations than at T0, T1, and T4, and higher pooled entire cast deviations than T1 were demonstrated (P ≤ .027).
CONCLUSIONS
The trueness of nanographene-reinforced casts was either similar to or higher than that of other casts. Dimensional changes were acceptable during the course of 1 month.
Topics: Computer-Aided Design; Dental Impression Technique; Maxilla; Imaging, Three-Dimensional
PubMed: 38498863
DOI: 10.11607/ijp.8877 -
The International Journal of... Feb 2024To assess crown die trueness using additive manufacturing (AM) based on intraoral scanning (IOS) data and compare it with stone models.
PURPOSE
To assess crown die trueness using additive manufacturing (AM) based on intraoral scanning (IOS) data and compare it with stone models.
MATERIALS AND METHODS
Crown dies with four finish line types- equigingival shoulder (SAE), subgingival shoulder (SAS), equigingival chamfer (CAE), and subgingival chamfer (CAS)-were incorporated into a reference model and scanned with a coordinate measurement machine (CMM; n = 1 scan). Trios4 (3Shape) scans generated a second reference dataset (IOS; n = 10 scans). Using scans, crown dies were produced with two different 3D printers (MAX UV385 [Asiga] and NextDent 5100 [3DSystems]; n = 10 per system). Stone dies were created from conventional impressions (n = 10). Specimens were digitized with a laboratory scanner (E4, 3Shape). Trueness was evaluated with Geomagic Control X (3DSystems). Data analysis was done using Shapiro-Wilk, Levene, ANOVA, and t tests (α < .05).
RESULTS
All crown dies fell within the clinically acceptable trueness range (150 μm). IOS exhibited significantly lower (P < .05; Δ ≤ 21.7 μm) or similar trueness compared to stone models. Asiga dies demonstrated similar and NextDent significantly lower marginal trueness than IOS (P < .05; Δ ≤ 57.3 μm). Most AM margin areas had significantly lower trueness than stone (P < .001; Δ ≤ 57.2 μm). Asiga outperformed NextDent (P < .001). Shoulder trueness surpassed chamfer in optical scans (P = .01). Finish line design and gingiva location did not have a significant impact on AM and stone models (P > .05).
CONCLUSIONS
Combining IOS and AM achieves clinically acceptable crown die trueness for single molar teeth. The choice of AM device is critical, with Asiga outperforming NextDent. Finish-line design has an impact on optical scans. Finish-line design and marginal gingiva location have little effect on AM trueness.
Topics: Workflow; Computer-Aided Design; Crowns; Tooth; Dental Impression Technique; Imaging, Three-Dimensional
PubMed: 38498861
DOI: 10.11607/ijp.8985 -
Cureus Feb 2024The introduction of three-dimensional (3D) printing in dentistry has mainly focused on applications such as surgical planning, computer-guided templates, and digital...
INTRODUCTION
The introduction of three-dimensional (3D) printing in dentistry has mainly focused on applications such as surgical planning, computer-guided templates, and digital impression conversions. Additive manufacturing (AM), also known as 3D printing, involves layering resin material sequentially to construct objects and is gaining recognition for its role in creating custom-made medical appliances. The field of orthodontics has also embraced this technological wave and with the advent of cost-effective printers and biocompatible resins, 3D printing has become increasingly feasible and popular in orthodontic clinics. The limitations of traditional plaster models may have prompted the emergence of 3D-printed models, but it led to enhancing treatment planning and device fabrication, particularly in orthodontics. Notable desktop printing technologies include fused deposition modelling (FDM), digital light processing (DLP), and stereolithography (SLA), each employing distinct methods and materials for fabricating appliances. Evaluating mechanical properties, like flexure strength, is crucial to determine the material's ability to withstand bending forces and thus prove useful in fabricating thermoformable appliances, surgical templates, etc. This study aims to assess the flexure strength of 3D-printed models using FDM, DLP, and SLA technology, providing insights into their suitability as replacements for conventional models and shedding some light on the durability and sustainability of 3D-printed models.
MATERIALS AND METHODOLOGY
Cuboids measuring 20 x 5 x 2 mm were cut from models, creating 10 samples per printer group. These samples underwent flexure strength testing using a three-point bending system in a universal testing machine.
RESULTS
The FDM group exhibited the highest flexure strength at 69.36 ± 6.03 MPa, while the DLP group showed the lowest flexure strength at 67.47 ± 20.58 MPa. The results can be attributed to the differences in resin materials used for fabrication, with FDM using acrylonitrile butadiene styrene (ABS) polymer and SLA/DLP using polymethyl methacrylate (PMMA), and also to the variation in their printing mechanism.
CONCLUSION
The findings affirm the suitability of FDM models for orthodontic applications, suggesting enhanced efficiency and reliability in clinical practices.
PubMed: 38496206
DOI: 10.7759/cureus.54312 -
The International Journal of... Feb 2024To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers.
PURPOSE
To evaluate and compare the accuracy of conventional and 3D-printed casts using five different 3D printers.
MATERIALS AND METHODS
In the control group (CG group, n = 5), five conventional impressions using light- and heavy-body polyvinyl siloxane were obtained from the master model, resulting in five stone models. In the test groups, five different scans were performed by a well-trained and experienced clinician using a TRIOS intraoral scanner. All data were exported in STL file format, processed, and sent to five 3D printers. Five casts were manufactured in each printer group: SG (CARES P20, Straumann); FG (Form 2, Formlabs); WG (Duplicator 7, Wanhao); ZG (Zenith D, Zenith); and MG (Moonray S100, Moonray). Measurements of the accuracy (trueness and precision) of the casts obtained from conventional elastomeric impressions and 3D-printing methods were accomplished using a 3D analysis software (Geomagic Control).
RESULTS
The FG group showed the lowest values for trueness (indicating a value closer to real dimensions), which were similar to the SG group only (P > .05). MG, WG, and ZG groups presented higher values and were similar compared to each other. Data on precision demonstrated that all 3D-printed groups showed lower values for precision (smaller deviation) when compared to the CG.
CONCLUSIONS
The trueness depends on the chosen 3D printer. All of the tested 3D printers were more precise than cast models obtained from conventional elastomeric impressions.
Topics: Computer-Aided Design; Dental Implants; Printing, Three-Dimensional; Dental Impression Technique; Imaging, Three-Dimensional
PubMed: 38489216
DOI: 10.11607/ijp.7361 -
La Tunisie Medicale Dec 2023The constant increase of both esthetic demands and advancement in materials and technologies have led to the development of guidelines to achieve optimal aesthetic... (Observational Study)
Observational Study
INTRODUCTION
The constant increase of both esthetic demands and advancement in materials and technologies have led to the development of guidelines to achieve optimal aesthetic results. These tools are useful to predict the teeth proportion and dimensions. Golden and Red proportion are the most described theories.
AIM
of present study was to evaluate the existence of both Golden and Red proportion in the maxillary anterior teeth among a North-African population.
METHODS
This was an observational study performed at the Fixed Prosthetic department of the dental clinic of Monastir, Tunisia. The study included participants with full intact anterior dentition. Those with diastema or teeth crowding were excluded. For each one, an alginate impression was done. Measures were, including the perceived width and length, have been taken on casts using digital caliper. Width ratios of maxillary lateral incisor to maxillary central incisor and lateral incisor to canine were calculated.
RESULTS
The study included 100 Tunisian participants including 97 females and 21 males. The maxillary central incisors were the largest (8.60±0.58mm) and the longest (99.71±1.14mm). The ratio was 0.89±0.09mm. Anterior teeth dimensions were not statistically not different between males and females. Significant differences were observed between calculated ratios with GP and to each other's. (p=0).
CONCLUSIONS
Either GP nor RP is applicable amongst the Tunisian Population.
Topics: Male; Female; Humans; Maxilla; Cuspid; Esthetics, Dental; Odontometry; Incisor
PubMed: 38477197
DOI: No ID Found -
The Journal of Prosthetic Dentistry Apr 2024Capturing accurate complete arch digital implant scans remains a challenging process because of the lack of recognizable anatomic landmarks. The effect of modified scan...
STATEMENT OF PROBLEM
Capturing accurate complete arch digital implant scans remains a challenging process because of the lack of recognizable anatomic landmarks. The effect of modified scan bodies (SBs) on improving scanning accuracy is unclear.
PURPOSE
The purpose of this in vitro study was to evaluate and compare the accuracy of a maxillary complete arch digital implant scan when using a specially designed geometric device with the accuracy of modified scan bodies.
MATERIAL AND METHODS
Four implants were placed in an edentulous maxillary model made of porous bone material with polyurethane attached gingiva. Scan bodies were attached to the implants and then digitized with a high precision laboratory scanner to create the reference scan. Round depressions were made on the buccal and palatal surfaces of the scan bodies, and the model was scanned with an intraoral scanner using 4 different scenarios: the model with no geometric device or modified scan bodies (ND-NM), device only without modified scan bodies (D-NM), no device but with modified scan bodies (ND-M), and device with modified scan bodies (D-M). Each group was scanned 10 times for a total of 40 scans. Trueness and precision were evaluated using inspection software to measure the 3D surface deviation. Trueness was measured by superimposing each test scan on the reference scan, and precision was calculated by superimposing the test scans of the same group with each other. Data were analyzed using the GraphPad Prism version 8.0.0 software program. Two-way ANOVA was performed to assess the effect of the device and modifications on trueness and precision (α=.05).
RESULTS
Both the geometric device and SB modifications had a significantly significant effect on trueness and precision (P<.001). Regarding trueness, group D-M had the lowest mean and standard deviation (0.158 ±0.028 mm) in contrast with group ND-NM, which had the highest deviation (0.282 ±0.038 mm). In terms of precision, group D-M showed the lowest mean and standard deviation (0.134 ±0.013 mm), while group ND-NM revealed the highest deviation (0.222 ±0.031 mm). However, no statistically significant interaction was found between the device and modifications regarding either trueness or precision (P>.05).
CONCLUSIONS
Using a specially designed geometric device improved both the trueness and precision of complete arch digital implant scans. The modified SBs had a positive influence on the scanning trueness and precision, and the best accuracy was achieved when using the geometric device and the modified SBs simultaneously.
Topics: Computer-Aided Design; Imaging, Three-Dimensional; Dental Implants; Dental Impression Technique; Models, Dental
PubMed: 38472074
DOI: 10.1016/j.prosdent.2024.02.020 -
Compendium of Continuing Education in... Mar 2024The clinical success of indirect restorations is directly correlated with their specific anatomic shape and design as well as marginal accuracy and overall precision of...
The clinical success of indirect restorations is directly correlated with their specific anatomic shape and design as well as marginal accuracy and overall precision of fit. These factors require a precise impression of the preparation and, to the extent necessary and possible, other teeth and supporting hard and soft tissues.
Topics: Dental Prosthesis Design; Dental Marginal Adaptation; Computer-Aided Design; Dental Impression Technique; Tooth; Dental Impression Materials
PubMed: 38460141
DOI: No ID Found -
Journal of Dentistry Apr 2024To evaluate the influence of intraoral scanning coverage (IOSC) on digital implant impression accuracy in various partially edentulous situations and predict the optimal...
OBJECTIVES
To evaluate the influence of intraoral scanning coverage (IOSC) on digital implant impression accuracy in various partially edentulous situations and predict the optimal IOSC.
METHODS
Five types of resin models were fabricated, each simulating single or multiple tooth loss scenarios with inserted implants and scan bodies. IOSC was subgrouped to cover two, four, six, eight, ten, and twelve teeth, as well as full arch. Each group underwent ten scans. A desktop scanner served as the reference. Accuracy was evaluated by measuring the Root mean square error (RMSE) values of scan bodies. A convolutional neural network (CNN) was trained to predict the optimal IOSC with different edentulous situations. Statistical analysis was performed using one-way ANOVA and Tukey's test.
RESULTS
For single-tooth-missing situations, in anterior sites, significantly better accuracy was observed in groups with IOSC ranging from four teeth to full arch (p < 0.05). In premolar sites, IOSC spanning four to six teeth were more accurate (p < 0.05), while in molar sites, groups with IOSC encompassing two to eight teeth exhibited better accuracy (p < 0.05). For multiple-teeth-missing situations, IOSC covering four, six, and eight teeth, as well as full arch showed better accuracy in anterior gaps (p < 0.05). In posterior gaps, IOSC of two, four, six or eight teeth were more accurate (p < 0.05). The CNN predicted distinct optimal IOSC for different edentulous scenarios.
CONCLUSIONS
Implant impression accuracy can be significantly impacted by IOSC in different partially edentulous situations. The selection of IOSC should be customized to the specific dentition defect condition.
CLINICAL SIGNIFICANCE
The number of teeth scanned can significantly affect digital implant impression accuracy. For missing single or four anterior teeth, scan at least four or six neighboring teeth is acceptable. In lateral cases, two neighboring teeth may suffice, but extending over ten teeth, including contralateral side, might deteriorate the scan.
Topics: Humans; Imaging, Three-Dimensional; Dental Impression Technique; Models, Dental; Dental Impression Materials; Mouth, Edentulous; Tooth Loss; Dental Implants; Computer-Aided Design
PubMed: 38458380
DOI: 10.1016/j.jdent.2024.104929 -
The Journal of Advanced Prosthodontics Feb 2024The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques.
PURPOSE
The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques.
MATERIALS AND METHODS
The study included 31 inlays for prosthodontics purposes of 31 patients: 15 based on intraoral digital impressions (DI group); and 16 based on a conventional impression technique (CI group). Inlays included occlusal and a non-occlusal surface. Inlays were milled in ceramic. The inlay-teeth interface was replicated by placing each inlay in its corresponding uncemented clinical preparation and taking interface impressions with silicone material from occlusal and free surfaces. Interface analysis was made using white light confocal microscopy (WLCM) (scanning area: 694 × 510 µm) from the impression samples. The gap size and the inlay overextension were measured from the microscopy topographies. For analytical purposes (i.e., 95-%-confidence intervals calculations and -value calculations), the procedure REGRESS in SUDAAN was used to account for clustering (i.e., multiple measurements). For p-value calculation, the log transformation of the dependent variables was used to normalize the distributions.
RESULTS
Marginal fit values for occlusal and free surfaces were affected by the type of impression. There were no differences between surfaces (occlusal vs. free). Gap obtained for DI group was 164 ± 84 µm and that for CI group was 209 ± 104 µm, and there were statistical differences between them ( = .041). Mean overextension values were 60 ± 59 µm for DI group and 67 ± 73 µm for CI group, and there were no differences between then ( = .553).
CONCLUSION
Digital impression achieved inlays with higher clinical marginal fit and performed better than the conventional silicone materials.
PubMed: 38455677
DOI: 10.4047/jap.2024.16.1.57