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3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: closed (20 June 2023) | Viewed by 20565

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Special Issue Editors

Dr. Alessandro Vichi

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Guest Editor

University of Portsmouth Dental Academy, William Beatty Building, Hampshire Terrace, Portsmouth PO1 2QG, UK
Interests: dental materials; restorative dentistry; prosthodontic; dental ceramics; dental polymers

Prof. Dr. Cecilia Goracci

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Guest Editor

Department of Medical Biotechnologies, University of Siena, Siena, Italy
Interests: dental materials; orthodontics; biostatistics; epidemiology; evidence-based dentistry

Special Issue Information

Dear Colleagues,

In last decade, CAD/CAM has progressively become a state-of-the-art technology in dentistry. Concurrently, 3D printing has emerged as a possible alternative to CAD/CAM for some procedures. The introduction of these techniques has been advantageous, particularly in some areas of dentistry such as restorative dentistry, prosthodontics, and orthodontics. The technological evolution of intraoral scanners, milling units and 3D printers has been accompanied by the development of new materials. Concerning CAD/CAM, a large variety of polymer-based materials as well as of hybrid materials has been made available to dentistry, providing a valuable alternative to ceramic materials. Particularly, reinforcing fibers (carbon, glass) and glass matrices have lately attracted the interest of research. In 3D printing, the recent introduction of 3D printable polymers for permanent restorations represents a pivotal step forward that is worthy of investigation.

This Special Issue aims to report the latest achievements in the field of polymer-based materials for digital manufacturing, presenting their mechanical and optical characteristics, as well as their clinical indications and workflows.

The Special Issue will collect original research studies presenting new trends and perspectives in the use of polymer-based materials for CAD-CAM manufacturing and 3D printing in dentistry, in addition to literature reviews summarizing the current knowledge in this field, with a special attention to the clinical relevance of the reported evidence. The contents of the Special Issue will specifically, though not exclusively, include:

Polymer based dental materials for CAD/CAM manufacturing;
Polymer based dental materials for 3D Printing;
Digitally processed prosthetic materials for temporary and permanent restorations;
Digitally processed materials for orthodontics.

Dr. Alessandro Vichi
Prof. Dr. Cecilia Goracci
Guest Editors

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Keywords

polymer based dental materials
CAD/CAM
3D printing
adhesion
restorative dentistry
prosthetic dentistry
orthodontics

Published Papers (8 papers)

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Research

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14 pages, 1179 KiB

Open AccessArticle

Bacterial Adhesion on Dental Polymers as a Function of Manufacturing Techniques

by Jörg Bächle, Cordula Merle, Sebastian Hahnel and Martin Rosentritt

Materials 2023, 16(6), 2373; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16062373 - 16 Mar 2023

Cited by 4 | Viewed by 1644

Abstract

The microbiological behavior of dental polymer materials is crucial to secure the clinical success of dental restorations. Here, the manufacturing process and the machining can play a decisive role. This study investigated the bacterial adhesion on dental polymers as a function of manufacturing techniques (additive/subtractive) and different polishing protocols. Specimens were made from polyaryletherketone (PEEK, PEKK, and AKP), resin-based CAD/CAM materials (composite and PMMA), and printed methacrylate (MA)-based materials. Surface roughness (R_z; R_a) was determined using a laser scanning microscope, and SFE/contact angles were measured using the sessile drop method. After salivary pellicle formation, in vitro biofilm formation was initiated by exposing the specimens to suspensions of Streptococcus mutans (S. mutans) and Streptococcus sanguinis (S. sanguinis). Adherent bacteria were quantified using a fluorometric assay. One-way ANOVA analysis found significant influences (p < 0.001) for the individual parameters (treatment and material) and their combinations for both types of bacteria. Stronger polishing led to significantly (p < 0.001) less adhesion of S. sanguinis (Pearson correlation PC = −0.240) and S. mutans (PC = −0.206). A highly significant (p = 0.010, PC = 0.135) correlation between S. sanguinis adhesion and R_z was identified. Post hoc analysis revealed significant higher bacterial adhesion for vertically printed MA specimens compared to horizontally printed specimens. Furthermore, significant higher adhesion of S. sanguinis on pressed PEEK was revealed comparing to the other manufacturing methods (milling, injection molding, and 3D printing). The milled PAEK samples showed similar bacterial adhesion. In general, the resin-based materials, composites, and PAEKs showed different bacterial adhesion. Fabrication methods were shown to play a critical role; the pressed PEEK showed the highest initial accumulations. Horizontal DLP fabrication reduced bacterial adhesion. Roughness < 10 µm or polishing appear to be essential for reducing bacterial adhesion. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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12 pages, 1224 KiB

Open AccessArticle

Repair Bond Strength of Conventionally and Digitally Fabricated Denture Base Resins to Auto-Polymerized Acrylic Resin: Surface Treatment Effects In Vitro

by Mohammed M. Gad, Zainab Albazroun, Fatimah Aldajani, Ahmed M. Elakel, Mai El Zayat, Sultan Akhtar, Soban Q. Khan, Saqib Ali and Ahmed M. Rahoma

Materials 2022, 15(24), 9062; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15249062 - 19 Dec 2022

Cited by 9 | Viewed by 2176

Abstract

Denture base fracture is one of the most annoying problems for both prosthodontists and patients. Denture repair is considered to be an appropriate solution rather than fabricating a new denture. Digital denture fabrication is widely spreading nowadays. However, the repair strength of CAD-CAM milled and 3D-printed resins is lacking. This study aimed to evaluate the effect of surface treatment on the shear bond strength (SBS) of conventionally and digitally fabricated denture base resins. One l heat-polymerized (Major base20), two milled (IvoCad, AvaDent), and three 3D-printed (ASIGA, NextDent, FormLabs) denture base resins were used to fabricate 10 × 10 × 3.3 acrylic specimens (N = 180, 30/resin, n = 10). Specimens were divided into three groups according to surface treatment; no treatment (control), monomer application (MMA), or sandblasting (SB) surface treatments were performed. Repair resin was bonded to the resin surface followed by thermocycling (5000 cycles). SBS was tested using a universal testing machine where a load was applied at the resin interface (0.5 mm/min). Data were collected and analyzed using ANOVA and a post hoc Tukey test (α = 0.05). SEM was used for failure type and topography of fractured surfaces analysis. The heat-polymerized and CAD-CAM milled groups showed close SBS values without significance (p > 0.05), while the 3D-printed resin groups showed a significant decrease in SBS (p < 0.0001). SBS increased significantly with monomer application (p < 0.0001) except for the ASIGA and NextDent groups, which showed no significant difference compared to the control groups (p > 0.05). All materials with SB surface treatment showed a significant increase in SBS when compared with the controls and MMA application (p < 0.0001). Adhesive failure type was observed in the control groups, which dramatically changed to cohesive or mixed in groups with surface treatment. The SBS of 3D-printed resin was decreased when compared with the conventional and CAD-CAM milled resin. Regardless of the material type, SB and MMA applications increased the SBS of the repaired resin and SB showed high performance. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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10 pages, 1063 KiB

Open AccessArticle

Surface Roughness and Color Stability of 3D-Printed Denture Base Materials after Simulated Brushing and Thermocycling

by Gülce Çakmak, Pedro Molinero-Mourelle, Marcella Silva De Paula, Canan Akay, Alfonso Rodriguez Cuellar, Mustafa Borga Donmez and Burak Yilmaz

Materials 2022, 15(18), 6441; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15186441 - 16 Sep 2022

Cited by 16 | Viewed by 2299

Abstract

Three-dimensional (3D) printing is increasingly used to fabricate denture base materials. However, information on the effect of simulated brushing and thermocycling on the surface roughness and color stability of 3D-printed denture base materials is lacking. The aim of this study was to evaluate the effect of brushing and thermocycling on the surface roughness and color stability of 3D-printed denture base materials and to compare with those of milled and heat-polymerized denture base resins. Disk-shaped specimens (Ø 10 mm × 2 mm) were prepared from 4 different denture base resins (NextDent Denture 3D+ (ND); Denturetec (SC); Polident d.o.o (PD); Promolux (CNV)) (n = 10). Surface roughness (R_a) values were measured before and after polishing with a profilometer. Initial color coordinates were measured by using a spectrophotometer after polishing. Specimens were then consecutively subjected to simulated brushing (10,000 cycles), thermocycling (10,000 cycles), and brushing (10,000 cycles) again. R_a and color coordinates were measured after each interval. Color differences (ΔE₀₀) between each interval were calculated and these values were further evaluated considering previously reported perceptibility (1.72 units) and acceptability (4.08 units) thresholds. Data were analyzed with Friedman, Kruskal–Wallis, and Mann–Whitney U tests (α = 0.05). R_a (p ≥ 0.051) and ΔE₀₀ (p ≥ 0.061) values among different time intervals within each material were similar. Within each time interval, significant differences in R_a (p ≤ 0.002) and ΔE₀₀ values (p ≤ 0.001) were observed among materials. Polishing, brushing, and thermocycling resulted in acceptable surface roughness for all materials that were either similar to or below 0.2 µm. Color of ND printed resin was affected by brushing and thermocycling. All materials had acceptable color stability when reported thresholds are considered. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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12 pages, 1499 KiB

Open AccessArticle

The Effect of Home and In-Office Bleaching on Microhardness and Color of Different CAD/CAM Ceramic Materials

by Ruwaida Z. Alshali and Mohammed A. Alqahtani

Materials 2022, 15(17), 5948; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15175948 - 28 Aug 2022

Cited by 6 | Viewed by 1284

Abstract

The aim of this study is to assess the effect of different bleaching agents on microhardness and color of CAD/CAM ceramics including IPS e.max CAD (lithium disilicate), VITA ENAMIC (polymer-infiltrated ceramic), and Celtra Duo CAD (zirconia-reinforced lithium silicate). Materials’ samples were divided into three groups (n = 10) and each received a different bleaching treatment; 20% carbamide peroxide, 35% carbamide peroxide, and 40% hydrogen peroxide. A fourth group was stored in water acting as a control. Vickers microhardness and spectrophotometric color measurements were taken at baseline and after bleaching. IPS e.max CAD showed a significant reduction (about 14%), while VITA ENAMIC showed a significant increase (about 78%) in microhardness after bleaching (p ˂ 0.001). Celtra Duo CAD did not demonstrate a significant change in microhardness (p ≥ 0.609). The color difference (ΔE_ab) after bleaching was 0.29 (±0.08), 2.84 (±0.64), and 1.99 (±0.37) for IPS e.max CAD, VITA ENAMIC, and Celtra Duo CAD, respectively. It could be concluded that the effect of bleaching on color and microhardness was mainly material-dependent. Bleaching significantly affected the microhardness of IPS e.max CAD and VITA ENAMIC. The color difference was within the clinically imperceptible range for IPS e.max CAD, while VITA ENAMIC and Celtra Duo CAD demonstrated perceptible color change. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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11 pages, 6580 KiB

Open AccessArticle

3D Printed Customized Facemask for Maxillary Protraction in the Early Treatment of a Class III Malocclusion: Proof-of-Concept Clinical Case

by Lorenzo Franchi, Alessandro Vichi, Patrizia Marti, Flavio Lampus, Simone Guercio, Annamaria Recupero, Veronica Giuntini and Cecilia Goracci

Materials 2022, 15(11), 3747; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15113747 - 24 May 2022

Cited by 10 | Viewed by 2637

Abstract

In order to improve fit and comfort, a maxillary protraction facemask customized to the patient’s anatomy was produced by means of 3D face scanning, digital design and additive manufacturing. An 8-year-old patient in need of early treatment for the Class III malocclusion received a rapid palatal expander and a Petit-type facemask, whose components were digitally designed on a 3D scan of the patient’s face. For face scanning, the iPad Pro 2018 tablet (Apple, Cupertino, CA, USA) with the Bellus3D DentalPro application (Bellus3D, Campbell, CA, USA) was used. Facemask components were modelled with 3D Blender software. The rests were 3D printed in BioMed Clear biocompatible resin (Formlabs, Somerville, MA, USA), and the bar in stainless steel. For greater comfort, the internal surface of the rests was lined with a polymer gel pad (Silipos, Niagara Falls, NY, USA). The manufacturing procedure of the customized facemask is patented. The patient wore the facemask at night for a period of 9 months. The patient’s experience was evaluated with a questionnaire at 1 week, 3, 6, and 10 months of treatment. The customized facemask was well accepted by the patient and obtained the expected treatment outcome. Furthermore, 3D face scanning, 3D modelling and 3D printing allow for the manufacturing of customized facemasks with improved fit and comfort, favoring patient compliance and treatment success. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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8 pages, 678 KiB

Open AccessArticle

Printing Accuracy and Flexural Properties of Different 3D-Printed Denture Base Resins

by Faisal D. al-Qarni and Mohammed M. Gad

Materials 2022, 15(7), 2410; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15072410 - 24 Mar 2022

Cited by 21 | Viewed by 3475

Abstract

Digital dentures can be fabricated by subtractive milling or, more recently, by 3D-printing technology. Several different 3D-printing technologies and materials are commercially available, and the differences in printing accuracy and mechanical behavior among them are unknown. Aim: This study evaluated the printing accuracy of 3D-printed denture base resins and assessed their flexural properties when compared with conventional heat-polymerized ones. Methods: A total of 40 acrylic specimens were prepared with four different materials: three 3D-printed resins, and a conventional heat polymerized resin was used as a control. The printing accuracy was evaluated by calculating the error rate of 3D-printed specimens compared with dimensions of the virtual design. Flexural strength and elastic modulus were assessed with a universal testing machine. One-way ANOVA and Kruskal–Wallis tests were used for analysis. Results: Printing accuracy across the tested materials was statistically different. Specimen length showed error rates between 1.3% and 2.4%, specimen width had error rates between 0.2% and 0.7%, and specimen thickness had error rates between 0.2% and 0.6%. Three-dimensional-printed specimens had lower flexural strength and elastic modulus values when compared with heat-polymerized specimens. Conclusions: The choice of material seems to influence printing accuracy, and to a lesser extent, flexural strength. However, it has no effect on the elastic modulus. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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12 pages, 1751 KiB

Open AccessArticle

Mechanical Properties, Cytotoxicity, and Fluoride Ion Release Capacity of Bioactive Glass-Modified Methacrylate Resin Used in Three-Dimensional Printing Technology

by Zbigniew Raszewski, Julita Kulbacka and Agnieszka Nowakowska-Toporowska

Materials 2022, 15(3), 1133; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15031133 - 01 Feb 2022

Cited by 12 | Viewed by 2190

Abstract

Background: Clinically, three-dimensional (3D) printing technology is becoming a popular and efficient dental processing technology. Recently, there has been an increasing demand for dental materials that exhibit bioactive properties. The present study aimed to evaluate the mechanical properties, cytotoxicity, and fluoride ion release capacity of 3D-printed dental resins modified with bioactive glass. Materials and methods: The resin FotoDent splint used in the production of removable orthodontic splints, was modified by the addition of two types of bioactive glasses that are capable of releasing fluoride ions. The novel materials used for the production of dental splints were examined for their mechanical, physical, and biological properties (fracture resistance, sorption, solubility, elution of nonpolymeric substances, and release of fluoride ions over time) and cytotoxic effects on cell cultures. Results: Initially, the fracture toughness of the 3D-printed resin was found to be 55 MPa, but after modification with glass, the resistance was reduced to about 50 MPa. Sorption and solubility values of the materials (19.01 ÷ 21.23 µg/mm³ and 0.42 ÷ 1.12 µg/mm³, respectively) complied with the safety limits imposed by ISO standard. Modified resins were capable of releasing fluoride ions, and the maximum releasing effect was observed after 14 days of incubation. Both the modified resins, after four days of contact with human gingival fibroblasts, exhibited moderate cytotoxic properties. Conclusions: The experimental results showed that modification of methacrylate resin, used in 3D printing technology, with bioactive glasses produces novel dental materials that possess desirable bioactive properties. The findings of this study indicate the potential ability of modified polymethacrylate resins to release fluoride ions in the oral cavity environment. The modified materials are characterized with a moderate decrease in physical properties and mild cytotoxicity on direct contact with human fibroblasts. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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Review

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15 pages, 475 KiB

Open AccessReview

Clinically Relevant Properties of 3D Printable Materials for Intraoral Use in Orthodontics: A Critical Review of the Literature

by Cecilia Goracci, Jovana Juloski, Claudio D’Amico, Dario Balestra, Alessandra Volpe, Jelena Juloski and Alessandro Vichi

Materials 2023, 16(6), 2166; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16062166 - 08 Mar 2023

Cited by 12 | Viewed by 3668

Abstract

The review aimed at analyzing the evidence available on 3D printable materials and techniques used for the fabrication of orthodontic appliances, focusing on materials properties that are clinically relevant. MEDLINE/PubMed, Scopus, and Cochrane Library databases were searched. Starting from an initial retrieval of 669 citations, 47 articles were finally included in the qualitative review. Several articles presented proof-of-concept clinical cases describing the digital workflow to manufacture a variety of appliances. Clinical studies other than these case reports are not available. The fabrication of aligners is the most investigated application of 3D printing in orthodontics, and, among materials, Dental LT Clear Resin (Formlabs) has been tested in several studies, although Tera Harz TC-85 (Graphy) is currently the only material specifically marketed for direct printing of aligners. Tests of the mechanical properties of aligners materials lacked homogeneity in the protocols, while biocompatibility tests failed to assess the influence of intraoral conditions on eluents release. The aesthetic properties of 3D-printed appliances are largely unexplored. The evidence on 3D-printed metallic appliances is also limited. The scientific evidence on 3D printable orthodontic materials and techniques should be strengthened by defining international standards for laboratory testing and by starting the necessary clinical trials. Full article

(This article belongs to the Special Issue 3D Printed and CAD-CAM Milled Polymer-Based Materials for Dentistry)

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