scholarly journals Impact of Dental Model Height on Thermoformed PET-G Aligner Thickness—An In Vitro Micro-CT Study

2021 ◽  
Vol 11 (15) ◽  
pp. 6674
Author(s):  
Benjamin Alexander Ihssen ◽  
Robert Kerberger ◽  
Nicole Rauch ◽  
Dieter Drescher ◽  
Kathrin Becker
Keyword(s):  
Reference Points ◽  
Distance Transform ◽  
Micro Ct ◽  
Potential Implication ◽  
Dental Model ◽  
Dental Models ◽  
3D Printed ◽  
The Mean ◽  
Upper Jaw

The aim of the present study was to investigate whether base height of 3D-printed dental models has an impact on local thickness values from polyethylene terephthalate glycol (PET-G) aligners. A total of 20 aligners were thermoformed on dental models from the upper jaw exhibiting either a 5 mm high (H) or narrow (N), i.e., 0 mm, base height. The aligners were digitized using micro-CT, segmented, and local thickness values were computed utilizing a 3D-distance transform. The mean thickness values and standard deviations were assessed for both groups, and local thickness values at pre-defined reference points were also recorded. The statistical analysis was performed using R. Aligners in group H were significantly thinner and more homogenous compared to group N (p < 0.001). Significant differences in thickness values were observed among tooth types between both groups. Whereas thickness values were comparable at cusp tips and occlusal/incisal/cervical measurement locations, facial and palatal surfaces were significantly thicker in group N compared to group H (p < 0.01). Within the limits of the study, the base height of 3D-printed models impacts on local thickness values of thermoformed aligners. The clinician should consider potential implication on exerted forces at the different tooth types, and at facial as well as palatal surfaces.

scholarly journals Evaluation of the 3D Printing Accuracy of a Dental Model According to Its Internal Structure and Cross-Arch Plate Design: An In Vitro Study

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5433
Author(s):  
Seung-Ho Shin ◽  
Jung-Hwa Lim ◽  
You-Jung Kang ◽  
Jee-Hwan Kim ◽  
June-Sung Shim ◽  
...  
Keyword(s):  
3D Printing ◽  
Internal Structure ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Thick Shell ◽  
Plate Design ◽  
Dental Model ◽  
3D Printed ◽  
Modeling Data

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.

Additive vs. Subtractive CAD/CAM Procedures in Manufacturing of the PMMA Interim Dental Crowns. A Comparative in vitro Study of Internal Fit

2020 ◽  
Vol 71 (1) ◽  
pp. 405-410
Author(s):  
Kamel Earar ◽  
Alexandru Andrei Iliescu ◽  
Gabriela Popa ◽  
Andrei Iliescu ◽  
Ioana Rudnic ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Dimensional Accuracy ◽  
Vitro Study ◽  
Dental Crowns ◽  
S 100 ◽  
Cad Cam ◽  
Dental Models ◽  
3D Printed ◽  
Internal Fit

CAD/CAM procedures are increasingly used to the manufacturing of 3D-designed PMMA interim dental crowns. The aim of this in vitro study was to compare the internal fit of interim PMMA crowns fabricated by subtractive versus additive CAD/CAM procedures. Starting from a Co-Cr CAD/CAM master abutment model, 20 standardized dental models of dental stone were done by double impression technique. Subsequently two groups of interim PMMA interim crowns, each of them having 10 specimens, were CAM obtained either by milling or 3D printing, using Exocad software package, milling machine Rolland DWX-50, and the 3D printer MoonRay S 100 respectively. An electronic digital caliper Powerfix Profi+ was used for measurements of the chrome cobalt abutment and crowns inner diameter in 4 directions (mesial-distal gingival, buccal-lingual gingival, mesial-distal occlusal, and buccal-lingual occlusal). The null hypothesis that the internal dimensional accuracy of interim PMMA crowns fabricated by DLP additive method would not be different compared to those obtained by milling procedure was rejected since the printed PMMA interim crowns were more accurate. This study concluded that the milled PMMA interim crowns show larger internal dimensional variations than the 3D printed ones. However, the fit variation among interim crowns fabricated by both procedures was statistically non significant, so that both CAM technologies may be equally used in manufacturing process.

3D-Printed Extracellular Matrix/Polyethylene Glycol Diacrylate Hydrogel Incorporating the Anti-inflammatory Phytomolecule Honokiol for Regeneration of Osteochondral Defects

2020 ◽  
Vol 48 (11) ◽  
pp. 2808-2818
Author(s):  
Shouan Zhu ◽  
Pengfei Chen ◽  
Yang Chen ◽  
Muzhi Li ◽  
Can Chen ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Polyethylene Glycol ◽  
Proinflammatory Cytokines ◽  
Osteochondral Defect ◽  
Micro Ct ◽  
Polyethylene Glycol Diacrylate ◽  
Glycol Diacrylate ◽  
3D Printed ◽  
Osteochondral Regeneration

Background: Osteoarthritis is the leading cause of disability worldwide; cartilage degeneration and defects are the central features. Significant progress in tissue engineering holds promise to regenerate damaged cartilage tissue. However, a formidable challenge is to develop a 3-dimensional (3D) tissue construct that can regulate local immune environment to facilitate the intrinsic osteochondral regeneration. Purpose: To evaluate efficacy of a 3D-printed decellularized cartilage extracellular matrix (ECM) and polyethylene glycol diacrylate (PEGDA) integrated novel scaffold (PEGDA/ECM) together with the natural compound honokiol (Hon) for regenerating osteochondral defect. Study Design: Controlled laboratory study. Methods: We used a stereolithography-based 3D printer for PEGDA/ECM bioprinting. A total of 36 Sprague-Dawley rats with cylindrical osteochondral defect in the trochlear groove of the femur were randomly assigned into 3 different treatments: no scaffold implantation (Defect group), 3D printed PEGDA/ECM scaffold alone (PEGDA/ECM group), or Hon suspended in a 3D-printed PEGDA/ECM scaffold (PEGDA/ECM/Hon group). 12 rats that underwent only medial parapatellar incision surgery were used as normal controls. The femur specimens were postoperatively harvested at 4 and 8 weeks for gross, micro-CT, and histological evaluations. The efficacy of PEGDA/ECM/Hon scaffold on the release of proinflammatory cytokines from the macrophages stimulated by lipopolysaccharide (LPS) was evaluated in-vitro. Results: In vitro results determined that PEGDA/ECM/Hon scaffold could suppress the release of proinflammatory cytokines from macrophages that were stimulated by LPS. Macroscopic images showed that the PEGDA/ECM/Hon group had significantly higher ICRS scoring than that of defect and PEGDA/ECM groups. Micro-CT evaluation demonstrated that much more bony tissue was formed in the defect sites implanted with the PEGDA/ECM scaffold or PEGDA/ECM/Hon scaffold compared with the untreated defects. Histological analysis showed that the PEGDA/ECM/Hon group had a significant enhancement in osteochondral regeneration at 4 and 8 weeks after surgery in comparison with the ECM/PEGDA or defect group. Conclusion: This study demonstrated that 3D printing of PEGDA/ECM hydrogel incorporating the anti-inflammatory phytomolecule honokiol could provide a promising scaffold for osteochondral defect repair.

scholarly journals Comparative evaluation of apical constriction position in incisor and molar teeth: An in vitro study

2018 ◽  
Vol 12 (02) ◽  
pp. 237-241
Author(s):  
Seyed Amir Mousavi ◽  
Alireza Farhad ◽  
Shirin Shahnaseri ◽  
Abbas Basiri ◽  
Erfan Kolahdouzan
Keyword(s):  
Root Canal ◽  
Statistical Significance ◽  
In Vitro Study ◽  
T Test ◽  
Reference Points ◽  
Root Canal Filling ◽  
Apical Constriction ◽  
Molar Teeth ◽  
The Mean

ABSTRACT Objective: The apical constriction (AC) and the apical foramen (AF) are the principal reference points used to determine the apical limit for instrumentation and root canal filling. AC varies in different races, and the aim of the current study was to measure and compare the distances from AC to AF and the anatomical apex (AA) in incisor and molar teeth in the Iranian population. Materials and Methods: Forty-five roots of incisor teeth and 45 roots of molar teeth were selected randomly in Isfahan Province, Iran. If the foramen was located toward the mesial or distal side of the apex, the cut was made mesiodistally, and if it was toward the buccal or lingual side, the section was made accordingly. Roots were examined under a microscope at ×25 magnification. The distances from AC to AF and AA were then estimated using a Motic camera. Descriptive statistics were used. The independent t-test was also used to compare distances in incisors and molars, and P = 0.05 was deemed to indicate statistical significance. Results: The mean distances between AC and AF were 0.847 ± 0.33 mm in incisors and 0.709 ± 0.27 mm in molars. The mean distances between AC and AA were 1.23 ± 0.39 mm in incisors and 1.01 ± 0.38 mm in molars. In an independent t-test, the distances between AC and AF differed significantly in incisors and molars (P = 0.035), but the distances between AC and AA did not (P = 0.172). Conclusion: The end points for root canal therapy should be 0.85 mm in incisors and 0.70 mm in molars.

scholarly journals A Proposed In Vitro Methodology for Assessing the Accuracy of Three-Dimensionally Printed Dental Models and the Impact of Storage on Dimensional Stability

2021 ◽  
Vol 11 (13) ◽  
pp. 5994
Author(s):  
Li Hsin Lin ◽  
Joshua Granatelli ◽  
Frank Alifui-Segbaya ◽  
Laura Drake ◽  
Derek Smith ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Reference Model ◽  
Three Dimensional ◽  
Posterior Region ◽  
Digital Light Processing ◽  
Dental Models ◽  
3D Printed ◽  
T1 And T2 ◽  
The Impact

The objective of this study was to propose a standardised methodology for assessing the accuracy of three-dimensional printed (3DP) full-arch dental models and the impact of storage using two printing technologies. A reference model (RM) comprising seven spheres was 3D-printed using digital light processing (MAX UV, MAX) and stereolithography (Form 2, F2) five times per printer. The diameter of the spheres (n = 35) represented the dimensional trueness (DT), while twenty-one vectors (n = 105) extending between the sphere centres represented the full-arch trueness (FT). Samples were measured at two (T1) and six (T2) weeks using a commercial profilometer to assess their dimensional stability. Significant (p < 0.05) contraction in DT occurred at T1 and T2 with a medium deviation of 108 µm and 99 µm for MAX, and 117 µm and 118 µm for F2, respectively. No significant (p > 0.05) deviations were detected for FT. The detected median deviations were evenly distributed across the arch for MAX at <50 µm versus F2, where the greatest error of 278 µm was in the posterior region. Storage did not significantly impact the model’s DT in contrast to FT (p < 0.05). The proposed methodology was able to assess the accuracy of 3DP. Storage significantly impacted the full-arch accuracy of the models up to 6 weeks post-printing.

scholarly journals Effects of Printing Parameters on the Fit of Implant-Supported 3D Printing Resin Prosthetics

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2533 ◽  
Author(s):  
Gang-Seok Park ◽  
Seong-Kyun Kim ◽  
Seong-Joo Heo ◽  
Jai-Young Koak ◽  
Deog-Gyu Seo
Keyword(s):  
3D Printing ◽  
Layer Thickness ◽  
Micro Ct ◽  
Marginal Fit ◽  
Dental Model ◽  
Marginal Discrepancy ◽  
3D Printed ◽  
Ct Data ◽  
Internal Gap ◽  
Printing Parameters

The purpose of the study was to investigate the influence of 3D printing parameters on fit and internal gap of 3D printed resin dental prosthesis. The dental model was simulated and fabricated for three-unit prostheses with two implants. One hundred prostheses were 3D printed with two-layer thicknesses for five build orientations using a resin (NextDent C&B; 3D systems, Soesterberg, The Netherlands) and ten prostheses were manufactured with a milling resin as control. The prostheses were seated and scanned with micro-CT (computerized tomography). Internal gap volume (IGV) was calculated from 3D reconstructed micro-CT data. IGV, marginal fit, and lengths of internal gaps were measured, and the values were analyzed statistically. For the 3D printed prostheses, IGV was smaller at 45°, 60°, and 90° compared to other build orientations. The marginal fit evaluated by absolute marginal discrepancy was smaller than other build orientations at 45° and 60°. IGV was smaller at 50 µm layer thickness than at 100 µm layer thickness, but the marginal fit was smaller at 100 µm layer thickness than at 50 µm layer thickness. The 3D printed prosthesis had smaller internal gap than the milled prosthesis. The marginal fit of the 3D printed resin prosthesis was clinically acceptable, and build orientation of 45° and 60° would be recommended when considering fit and internal gap.

scholarly journals Accuracy of 3-Dimensionally Printed Full-Arch Dental Models: A Systematic Review

2020 ◽  
Vol 9 (10) ◽  
pp. 3357 ◽  
Author(s):  
Yasaman Etemad-Shahidi ◽  
Omel Baneen Qallandar ◽  
Jessica Evenden ◽  
Frank Alifui-Segbaya ◽  
Khaled Elsayed Ahmed
Keyword(s):  
Meta Analysis ◽  
Inclusion Criteria ◽  
Digital Light Processing ◽  
Dental Model ◽  
Dental Models ◽  
3D Printed ◽  
And Storage ◽  
Manufacturing Parameters ◽  
Base Design ◽  
Or Applications

The use of additive manufacturing in dentistry has exponentially increased with dental model construction being the most common use of the technology. Henceforth, identifying the accuracy of additively manufactured dental models is critical. The objective of this study was to systematically review the literature and evaluate the accuracy of full-arch dental models manufactured using different 3D printing technologies. Seven databases were searched, and 2209 articles initially identified of which twenty-eight studies fulfilling the inclusion criteria were analysed. A meta-analysis was not possible due to unclear reporting and heterogeneity of studies. Stereolithography (SLA) was the most investigated technology, followed by digital light processing (DLP). Accuracy of 3D printed models varied widely between <100 to >500 μm with the majority of models deemed of clinically acceptable accuracy. The smallest (3.3 μm) and largest (579 μm) mean errors were produced by SLA printers. For DLP, majority of investigated printers (n = 6/8) produced models with <100 μm accuracy. Manufacturing parameters, including layer thickness, base design, postprocessing and storage, significantly influenced the model’s accuracy. Majority of studies supported the use of 3D printed dental models. Nonetheless, models deemed clinically acceptable for orthodontic purposes may not necessarily be acceptable for the prosthodontic workflow or applications requiring high accuracy.

scholarly journals Accuracy of different tooth surfaces on 3D printed dental models: orthodontic perspective

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Ting Dong ◽  
Xiaoting Wang ◽  
Lunguo Xia ◽  
Lingjun Yuan ◽  
Niansong Ye ◽  
...  
Keyword(s):  
Posterior Teeth ◽  
Stl File ◽  
Tukey Test ◽  
Occlusal Surfaces ◽  
Tooth Surfaces ◽  
Dental Models ◽  
3D Printed ◽  
The Mean ◽  
Lower Limits ◽  
Pits And Fissures

Abstract Background Few studies have been reported regarding the accuracy of 3D-printed models for orthodontic applications. The aim of this study was to assess the accuracy of 3D-printed dental models of different tooth surfaces. Methods Thirty volunteers were recruited from the hospital, and then their dental models were produced by means of oral scanning and a stereolithography-based 3D printer. Each printed model was digitally scanned and compared with the oral-scanned STL file via superimposition analysis. A color map was used to assess the accuracy of different surfaces (occlusal, buccal, lingual) of anterior and posterior teeth. The Tukey test was used to evaluate the differences between the superimposition. Results Statistically significant differences were found in the average deviations of different tooth surfaces (P < 0.05). The mean average absolute deviations of the occlusal surfaces of posterior teeth were greater than those of other surfaces. Percentages of points beyond the upper and lower limits of different tooth surfaces displayed the same results (P < 0.05). Conclusions Occlusal surfaces, especially pits and fissures of posterior teeth on 3D printed maxillary dental models, showed greater distortions than those of other teeth and regions.

scholarly journals Accuracy of 3D-Printed Dental Models of Different Tooth Surfaces

2020 ◽  
Author(s):  
Ting Dong ◽  
Xiaoting Wang ◽  
Lunguo Xia ◽  
Niansong Ye ◽  
Lingjun Yuan ◽  
...  
Keyword(s):  
3D Printer ◽  
Posterior Teeth ◽  
Stl File ◽  
Occlusal Surfaces ◽  
Tooth Surfaces ◽  
Dental Models ◽  
3D Printed ◽  
The Mean ◽  
Lower Limits ◽  
Pits And Fissures

Abstract Background: Few studies have been reported regarding the accuracy of 3D-printed models for orthodontic applications. The aim of this study was to assess the accuracy of 3D-printed dental models of different tooth surfaces.Methods：Thirty maxillary dental models were produced by means of a stereolithography-based 3D printer. Each printed model was digitally scanned and compared with the oral-scanned STL file via superimposition analysis, with a colour map used to assess the accuracy of different surfaces of anterior and posterior teeth.Results: Statistically significant differences were found in the average deviations of different tooth surfaces. The mean average absolute deviations of the occlusal surfaces of posterior teeth were greater than those of other surfaces. Percentages of points beyond the upper and lower limits of different tooth surfaces displayed the same results.Conclusions: The occlusal surfaces of posterior teeth on 3D-printed dental models show greater deviations than those of other regions, especially in pits and fissures.

scholarly journals Impact of Aging on the Accuracy of 3D-Printed Dental Models: An In Vitro Investigation

2020 ◽  
Vol 9 (5) ◽  
pp. 1436 ◽  
Author(s):  
Tim Joda ◽  
Lea Matthisson ◽  
Nicola U. Zitzmann
Keyword(s):  
Reference Model ◽  
In Vitro Study ◽  
Deviation Analysis ◽  
Fixed Dental Prosthesis ◽  
In Vitro Investigation ◽  
Dental Models ◽  
3D Printed ◽  
Level Of Significance ◽  
The Impact

The aim of this in vitro study was to analyze the impact of model aging on the accuracy of 3D-printed dental models. A maxillary full-arch reference model with prepared teeth for a three-unit fixed dental prosthesis was scanned ten times with an intraoral scanner (3Shape TRIOS Pod) and ten models were 3D printed (Straumann P-Series). All models were stored under constant conditions and digitized with a desktop scanner after 1 day; 1 week; and 2, 3, and 4 weeks. For accuracy, a best-fit algorithm was used to analyze the deviations of the abutment teeth (GFaI e.V Final Surface®). Wilcoxon Rank Sum Tests were used for comparisons with the level of significance set at α = 0.05. Deviation analysis of the tested models showed homogenous intragroup distance calculations at each timepoint. The most accurate result was for 1 day of aging (3.3 ± 1.3 µm). A continuous decrease in accuracy was observed with each aging stage from day 1 to week 4. A time-dependent difference was statistically significant after 3 weeks (p = 0.0008) and 4 weeks (p < 0.0001). Based on these findings, dental models should not be used longer than 3 to 4 weeks after 3D printing for the fabrication of definitive prosthetic reconstructions.

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