Editorial

4 pages, 205 KiB

Open AccessEditorial

by Célio Gabriel Figueiredo-Pina and Ana Paula Serro

Materials 2023, 16(14), 4972; https://doi.org/10.3390/ma16144972 - 12 Jul 2023

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Due to increased life expectancy and greater concern among populations regarding oral health problems and aesthetics, in the last few years, there has been a growing demand for dental structures and devices to replace/restore missing/damaged teeth [...] Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

Research

Jump to: Editorial, Review

22 pages, 6112 KiB

Open AccessArticle

Manufacturing and Characterization of Dental Crowns Made of 5-mol% Yttria Stabilized Zirconia by Digital Light Processing

by Jae-Min Jung, Gyu-Nam Kim, Young-Hag Koh and Hyoun-Ee Kim

Materials 2023, 16(4), 1447; https://doi.org/10.3390/ma16041447 - 09 Feb 2023

Cited by 6 | Viewed by 2284

Abstract

We herein report manufacturing of dental crowns made of 5-mol% yttria partially stabilized zirconia (5Y-PSZ) with desired mechanical properties, optical translucency and dimensional accuracy using digital light processing (DLP). To this end, all processing parameters were carefully controlled and optimized. First, 5Y-PSZ particles [...] Read more.

We herein report manufacturing of dental crowns made of 5-mol% yttria partially stabilized zirconia (5Y-PSZ) with desired mechanical properties, optical translucency and dimensional accuracy using digital light processing (DLP). To this end, all processing parameters were carefully controlled and optimized. First, 5Y-PSZ particles with a bimodal distribution were prepared via calcination of as-received granules and subsequent ball-milling and then used to formulate 5Y-PSZ suspensions with a high solid loading of 50 vol% required for high densification after sintering. Dispersant content was also optimized. To provide high dimensional accuracy, initial dimensions of dental crowns for 3D printing were precisely determined by considering increase and decrease in dimensions during photopolymerization and sintering, respectively. Photopolymerization time was also optimized for a given layer thickness of 50 μm to ensure good bonding between layers. A multi-step debinding schedule with a slow heating rate was employed to avoid formation of any defects. After sintering at 1500 °C for 2 h, 5Y-PSZ could be almost fully densified without noticeable defects within layers and at interfaces between layers. They had high relative densities (99.03 ± 0.39%) with a high cubic phase content (59.1%). These characteristics allowed for achievement of reasonably high mechanical properties (flexural strength = 625.4 ± 75.5 MPa and Weibull modulus = 7.9) and % transmittance (31.4 ± 0.7%). In addition, 5Y-PSZ dental crowns showed excellent dimensional accuracy (root mean square (RMS) for marginal discrepancy = 44.4 ± 10.8 μm and RMS for internal gap = 22.8 ± 1.6 μm) evaluated by the 3D scanning technique. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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13 pages, 3014 KiB

Open AccessArticle

Comparative Evaluation of Surface Roughness and Hardness of 3D Printed Resins

by Yousif A. Al-Dulaijan, Leenah Alsulaimi, Reema Alotaibi, Areej Alboainain, Haidar Alalawi, Sami Alshehri, Soban Q. Khan, Mohammed Alsaloum, Hamad S. AlRumaih, Abdulkareem A. Alhumaidan and Mohammed M. Gad

Materials 2022, 15(19), 6822; https://doi.org/10.3390/ma15196822 - 01 Oct 2022

Cited by 18 | Viewed by 2575

Abstract

The effect of printing parameters on the surface characteristics of three-dimensional (3D)-printed denture base resins (DBRs) is neglected. Therefore, this study investigated the effect of printing orientation and post-curing time on the surface roughness and hardness. One conventional heat-polymerized (HP) resin and two [...] Read more.

The effect of printing parameters on the surface characteristics of three-dimensional (3D)-printed denture base resins (DBRs) is neglected. Therefore, this study investigated the effect of printing orientation and post-curing time on the surface roughness and hardness. One conventional heat-polymerized (HP) resin and two 3D-printing resins (NextDent (ND) and ASIGA (AS)) were used to fabricate a total of 250-disc (10 × 2.5 mm) specimens. ND and AS specimens were printed with different orientations (0-, 45-, and 90-degree) and each orientation group was subjected to four post-curing times (30, 60, 90, 120 min). Printed specimens were thermo-cycled (10,000 cycles) followed by the measuring of surface roughness (Profilometer (Ra)) and hardness (a Vickers hardness (VH)). ANOVA and post hoc tests were used for data analysis (α = 0.05) at significant levels. AS and ND showed no significant changes in Ra when compared with HP (p ˃ 0.05), except the 45-degree orientation (AS/90 min and AS/120 min) significantly increased surface roughness (p ˂ 0.001). There was no significant difference in Ra with different orientations and post-curing time for both materials AS and ND (p ˃ 0.05). Compared with HP, 3D-printed DBRs showed low VH values (p ˂ 0.001). For AS, 90-degree orientation showed a significant decrease in VH at 60, 90, and 120 min when compared with 0- and 45-degree orientation (p ˂ 0.001), while ND showed no significant difference in VH with different printing orientations (p ˃ 0.05). The VH of AS and ND improved when increasing post-curing time to 120 min (p ˂ 0.001), and the printing orientations and post-curing time did not affect the Ra of 3D-printed DBRs. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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13 pages, 29609 KiB

Open AccessArticle

Understanding the Stress Distribution on Anatomic Customized Root-Analog Dental Implant at Bone-Implant Interface for Different Bone Densities

by Pawhat Nimmawitt, Abdul Azeez Abdu Aliyu, Boonrat Lohwongwatana, Sirida Arunjaroensuk, Chedtha Puncreobutr, Nikos Mattheos and Atiphan Pimkhaokham

Materials 2022, 15(18), 6379; https://doi.org/10.3390/ma15186379 - 14 Sep 2022

Cited by 10 | Viewed by 1801

Abstract

The aim of this study is to assess the stress distribution on the bone tissue and bone-implant interface of a customized anatomic root-analog dental implant (RAI) by means of finite element analysis (FEA) for different types of bone density. A mandibular right second [...] Read more.

The aim of this study is to assess the stress distribution on the bone tissue and bone-implant interface of a customized anatomic root-analog dental implant (RAI) by means of finite element analysis (FEA) for different types of bone density. A mandibular right second premolar was selected from the CBCT database. A DICOM file was converted to an STL file to create a CAD model in FEA software. The bone boundary model was created, while bone density types I–IV were determined. Von Mises stress was measured at bone tissues and bone-implant interfaces. To validate the models, the RAI was 3D printed through a laser powder-bed fusion (L-PBF) approach. The results revealed that all RAI designs could not cause plastic deformation or fracture resulting in lower stress than the ultimate tensile stress of natural bone and implant. Compared to a conventional screw-type implant, RAIs possess a more favorable stress distribution pattern around the bone tissue and the bone-implant interface. The presence of a porous structure was found to reduce the stress at cancellous bone in type IV bone density. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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14 pages, 4770 KiB

Open AccessArticle

Development of 3D Slurry Printing Technology with Submersion-Light Apparatus in Dental Application

by Cho-Pei Jiang, M. Fahrur Rozy Hentihu, Yung-Chang Cheng, Tzu-Yi Lei, Richard Lin and Zhangwei Chen

Materials 2021, 14(24), 7873; https://doi.org/10.3390/ma14247873 - 19 Dec 2021

Cited by 6 | Viewed by 2709

Abstract

This study proposes an innovative three-dimensional printing technology with submersion-light apparatus. A zirconia powder with an average particle size of 0.5 µm is mixed with 1,6-Hexanediol diacrylate (HDDA) and photo-initiator to form a slurry. The weight percentage of zirconia powder to HDDA is [...] Read more.

This study proposes an innovative three-dimensional printing technology with submersion-light apparatus. A zirconia powder with an average particle size of 0.5 µm is mixed with 1,6-Hexanediol diacrylate (HDDA) and photo-initiator to form a slurry. The weight percentage of zirconia powder to HDDA is 70:30 wt.%. A light engine box is submerged in a slurry and emits a layered pattern to induce photopolymerization and transform a slurry into a printed green body. Green body sintering parameters for the first and second stages are 380 °C with a holding time of 1.5 h and 1550 °C with a holding time of 2 h. The sintered parts’ length, width, and height shrinkage ratios are 29.9%, 29.7%, and 30.6%. The ball milling decreases the powder particle size to 158 ± 16 nm and the mean grain size of the sintered part is 423 ± 25 nm. The sintered part has an average hardness of 1224 (HV), a density of 5.45 g/cm³, and a flexural strength of 641.04 MPa. A three-unit zirconia dental bridge also has been fabricated with a clinically acceptable marginal gap. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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12 pages, 2909 KiB

Open AccessArticle

Evaluating the Three-Dimensional Printing Accuracy of Partial-Arch Models According to Outer Wall Thickness: An In Vitro Study

by Seung-Ho Shin, Jae-Sung Kwon, June-Sung Shim and Jong-Eun Kim

Materials 2021, 14(22), 6734; https://doi.org/10.3390/ma14226734 - 09 Nov 2021

Cited by 6 | Viewed by 1833

Abstract

The printing accuracy of three-dimensional (3D) dental models using photopolymer resin affects dental diagnostic procedures and prostheses. The accuracy of research into the outer wall thickness and printing direction data for partial-arch model printing has been insufficient. This study analyzed the effects of [...] Read more.

The printing accuracy of three-dimensional (3D) dental models using photopolymer resin affects dental diagnostic procedures and prostheses. The accuracy of research into the outer wall thickness and printing direction data for partial-arch model printing has been insufficient. This study analyzed the effects of wall thickness and printing direction accuracy. Anterior and posterior partial-arch models were designed with different outer wall thicknesses. After 3D printing, a trueness analysis was performed. Those with full-arch models were the control group. The full-arch model had an error value of 73.60 ± 2.61 µm (mean ± standard deviation). The error values for the partial-arch models with 1-, 2-, and 3-mm thick outer walls were 54.80 ± 5.34, 47.58 ± 7.59, and 42.25 ± 9.19 μm, respectively, and that for the fully filled model was 38.20 ± 4.63 μm. The printing accuracies differed significantly between 0 degrees and 60 degrees, at 49.54 ± 8.16 and 40.66 ± 6.80 μm, respectively (F = 153.121, p < 0.001). In conclusion, the trueness of the partial-arch model was better than that of the full-arch model, and models with thick outer walls at 60 degrees were highly accurate. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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10 pages, 1832 KiB

Open AccessArticle

Influence of Build Orientation, Geometry and Artificial Saliva Aging on the Mechanical Properties of 3D Printed Poly(ε-caprolactone)

by Ana C. Pinho and Ana P. Piedade

Materials 2021, 14(12), 3335; https://doi.org/10.3390/ma14123335 - 16 Jun 2021

Cited by 5 | Viewed by 1680

Abstract

Additive manufacturing of polymers has evolved from rapid prototyping to the production of functional components/parts with applications in distinct areas, ranging from health to aeronautics. The possibility of producing complex customized geometries with less environmental impact is one of the critical factors that [...] Read more.

Additive manufacturing of polymers has evolved from rapid prototyping to the production of functional components/parts with applications in distinct areas, ranging from health to aeronautics. The possibility of producing complex customized geometries with less environmental impact is one of the critical factors that leveraged the exponential growth of this processing technology. Among the several processing parameters that influence the properties of the parts, the geometry (shape factor) is amid less reported. Considering the geometric complexity of the mouth, including the uniqueness of each teething, this study can contribute to a better understanding of the performance of polymeric devices used in the oral environment for preventive, restorative, and regenerative therapies. Thus, this work aims to evaluate 3D printed poly(ε-caprolactone) mechanical properties with different build orientations and geometries. Longitudinal and transversal toolpaths produced specimens with parallelepiped and tubular geometry. Moreover, as it is intended to develop devices for dentistry, the influence of artificial saliva on mechanical properties was determined. The research concluded that the best mechanical properties are obtained for parallelepiped geometry with a longitudinal impression and that aging in artificial saliva negatively influences all the mechanical properties evaluated in this study. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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15 pages, 3187 KiB

Open AccessArticle

Evaluation of Bacterial Adhesion to the ZrO₂ Atomic Layer Deposited on the Surface of Cobalt-Chromium Dental Alloy Produced by DMLS Method

by Anna Ziębowicz, Agata Sambok-Kiełbowicz, Witold Walke, Aldona Mzyk, Kamil Kosiel, Jerzy Kubacki, Bohdan Bączkowski, Mirosława Pawlyta and Bogusław Ziębowicz

Materials 2021, 14(5), 1079; https://doi.org/10.3390/ma14051079 - 26 Feb 2021

Cited by 6 | Viewed by 1659

Abstract

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO₂) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the [...] Read more.

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO₂) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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10 pages, 1442 KiB

Open AccessFeature PaperArticle

Impact of Layer Thickness and Storage Time on the Properties of 3D-Printed Dental Dies

by Aya Sabbah, Georgios Romanos and Rafael Delgado-Ruiz

Materials 2021, 14(3), 509; https://doi.org/10.3390/ma14030509 - 21 Jan 2021

Cited by 24 | Viewed by 2667

Abstract

The purpose of this study was to evaluate the effect of printing layer thickness on the repeatability and surface roughness of 3D-printed dies and detect the effect of layer thickness and storage time on the dimensional stability of 3D-printed dies. One stereolithography (STL) [...] Read more.

The purpose of this study was to evaluate the effect of printing layer thickness on the repeatability and surface roughness of 3D-printed dies and detect the effect of layer thickness and storage time on the dimensional stability of 3D-printed dies. One stereolithography (STL) file of an upper molar prepared for a full ceramic crown was used to print three groups of dies: 25 µm, 50 µm, and 100 µm. Repeatability was evaluated by linear and area measurements with a digital caliper and a digital metrology microscope. Dimensional stability was analyzed at 3 weeks, 6 months, and 1 year of storage time. Surface roughness parameters were measured with a 3D confocal laser scanning microscope. Statistics were completed using one-way analysis of variance and Tukey’s post hoc tests, p < 0.05. Printing time decreased as layer thickness increased. All groups showed high repeatability and comparable surface roughness while showing differences in their linear dimensions and surface areas. At the 3 week storage interval, dimensional changes were observed in all groups. Within this experimental study’s constraints, it can be concluded that changing the 3D-printing layer thickness does not affect the repeatability or the surface roughness of the product; meanwhile, changes to the layer thickness and storage time influence the dimensional stability of 3D-printed dies. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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10 pages, 4609 KiB

Open AccessArticle

Comparison of 3D-Printed Dental Implants with Threaded Implants for Osseointegration: An Experimental Pilot Study

by Ling Li, Jungwon Lee, Heithem Ben Amara, Jun-Beom Lee, Ki-Sun Lee, Sang-Wan Shin, Yong-Moo Lee, Byoungkook Kim, Pangyu Kim and Ki-Tae Koo

Materials 2020, 13(21), 4815; https://doi.org/10.3390/ma13214815 - 28 Oct 2020

Cited by 14 | Viewed by 3276

Abstract

This study aimed to compare bone healing and implant stability for three types of dental implants: a threaded implant, a three-dimensional (3D)-printed implant without spikes, and a 3D-printed implant with spikes. In four beagle dogs, left and right mandibular premolars (2nd, 3rd, and [...] Read more.

This study aimed to compare bone healing and implant stability for three types of dental implants: a threaded implant, a three-dimensional (3D)-printed implant without spikes, and a 3D-printed implant with spikes. In four beagle dogs, left and right mandibular premolars (2nd, 3rd, and 4th) and 1st molars were removed. Twelve weeks later, three types of titanium implants (threaded implant, 3D-printed implant without spikes, and 3D-printed implant with spikes) were randomly inserted into the edentulous ridges of each dog. Implant stability measurements and radiographic recordings were taken every two weeks following implant placement. Twelve weeks after implant surgery, the dogs were sacrificed and bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) were compared between groups. At implant surgery, the primary stability was lower for the 3D-printed implant with spikes (74.05 ± 5.61) than for the threaded implant (83.71 ± 2.90) (p = 0.005). Afterwards, no significant difference in implants’ stability was observed between groups up to post-surgery week 12. Histomorphometrical analysis did not reveal a significant difference between the three implants for BIC (p = 0.101) or BAFO (p = 0.288). Within the limits of this study, 3D-printed implants without spikes and threaded implants showed comparable implant stability measurements, BIC, and BAFO. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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Review

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34 pages, 2735 KiB

Open AccessReview

Recent Advances on 3D-Printed Zirconia-Based Dental Materials: A Review

by Ana Catarina Branco, Rogério Colaço, Célio Gabriel Figueiredo-Pina and Ana Paula Serro

Materials 2023, 16(5), 1860; https://doi.org/10.3390/ma16051860 - 24 Feb 2023

Cited by 20 | Viewed by 5281

Abstract

Zirconia-based materials are widely used in dentistry due to their biocompatibility and suitable mechanical and tribological behavior. Although commonly processed by subtractive manufacturing (SM), alternative techniques are being explored to reduce material waste, energy consumption and production time. 3D printing has received increasing [...] Read more.

Zirconia-based materials are widely used in dentistry due to their biocompatibility and suitable mechanical and tribological behavior. Although commonly processed by subtractive manufacturing (SM), alternative techniques are being explored to reduce material waste, energy consumption and production time. 3D printing has received increasing interest for this purpose. This systematic review intends to gather information on the state of the art of additive manufacturing (AM) of zirconia-based materials for dental applications. As far as the authors know, this is the first time that a comparative analysis of these materials’ properties has been performed. It was performed following the PRISMA guidelines and using PubMed, Scopus and Web of Science databases to select studies that met the defined criteria without restrictions on publication year. Stereolithography (SLA) and digital light processing (DLP) were the techniques most focused on in the literature and the ones that led to most promising outcomes. However, other techniques, such as robocasting (RC) and material jetting (MJ), have also led to good results. In all cases, the main concerns are centered on dimensional accuracy, resolution, and insufficient mechanical strength of the pieces. Despite the struggles inherent to the different 3D printing techniques, the commitment to adapt materials, procedures and workflows to these digital technologies is remarkable. Overall, the research on this topic can be seen as a disruptive technological progress with a wide range of application possibilities. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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17 pages, 698 KiB

Open AccessReview

Mechanical Properties of Fused Deposition Modeling of Polyetheretherketone (PEEK) and Interest for Dental Restorations: A Systematic Review

by Vanessa Moby, Lucien Dupagne, Vincent Fouquet, Jean-Pierre Attal, Philippe François and Elisabeth Dursun

Materials 2022, 15(19), 6801; https://doi.org/10.3390/ma15196801 - 30 Sep 2022

Cited by 8 | Viewed by 1867

Abstract

The aim of this systematic review was to determine the optimal printing parameters for the producing of fused deposition modeling (FDM) 3D-printed polyetheretherketone (PEEK) elements with mechanical properties suitable for dental restorations. Indeed, the mechanical properties are a critical prerequisite for the study [...] Read more.

The aim of this systematic review was to determine the optimal printing parameters for the producing of fused deposition modeling (FDM) 3D-printed polyetheretherketone (PEEK) elements with mechanical properties suitable for dental restorations. Indeed, the mechanical properties are a critical prerequisite for the study of other parameters, such as physical, aesthetic and biological properties. An exhaustive electronic search was carried out in the PubMed, Embase and Web of knowledge databases to gather all the studies evaluating the influence of the printing parameters on the obtained mechanical properties of FDM 3D-printed PEEK elements were selected. Initially, the search resulted in 614 eligible papers. Independent screenings of the abstracts were performed by two authors to identify the articles related to the question. Twenty-nine studies were selected, of which eleven were further excluded after reading of the full text, and finally, eighteen articles were included in this review. The studies were difficult to compare due to the variability of the printing parameters and the types of PEEK. However, it seems interesting to use a high infill rate, a high chamber temperature close to that of the printing temperature and a heat post-treatment to obtain 3D PEEK elements presenting properties adapted to use as dental restorations. The analysis of the available literature suggested that the properties of PEEK could make it an interesting material in dental restorations to be performed with FDM additive manufacturing. Full article

(This article belongs to the Special Issue 3D Printing for Dental Applications)

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