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Year:2019
Areviewonchemicalcomposition,mechanicalproperties,and
manufacturingworkowofadditivelymanufacturedcurrentpolymersfor
interimdentalrestorations
Revilla-León,Marta;Meyers,MatthewJ;Zandinejad,Amirali;Özcan,Mutlu
Abstract:OBJECTIVESAdditivemanufacturing(AM)technologiescanbeusedtofabricate3D-printed
interimdentalrestorations.Theaimofthisreviewistoreportthemanufacturingworkow,itschemical
composition,andthemechanicalpropertiesthatmaysupporttheirclinicalapplication.OVERVIEW
Thesenew3D-printingprovisionalmaterialsaretypicallycomposedofmonomersbasedonacrylices-
tersorlledhybridmaterial.ThemostcommonlyusedAMmethodstomanufacturedentalprovisional
restorationsarestereolithography(SLA)andmaterialjetting(MJ)technologies.Totheknowledgeofthe
authors,thereisnopublishedarticlethatanalyzesthechemicalcompositionofthesenew3D-printing
materials.Becauseofprotocoldisparities,technologyselected,andparametersoftheprintersandma-
terialused,itisnotablydiculttocomparemechanicalpropertiesresultsobtainedindierentstudies.
CONCLUSIONSAlthoughthereisagrowingdemandforthesehigh-techrestorations,additionalinfor-
mationregardingthechemicalcompositionandmechanicalpropertiesofthesenewprovisionalprinted
materialsisrequired.CLINICALSIGNIFICANCEAdditivemanufacturingtechnologiesareacurrent
optiontofabricateprovisionaldentalrestorations;however,thereisverylimitedinformationregarding
itschemicalcompositionandmechanicalpropertiesthatmaysupporttheirclinicalapplication.
DOI:https://doi.org/10.1111/jerd.12438
PostedattheZurichOpenRepositoryandArchive,UniversityofZurich
ZORAURL:https://doi.org/10.5167/uzh-184761
JournalArticle
AcceptedVersion
Originallypublishedat:
Revilla-León,Marta;Meyers,MatthewJ; Zandinejad, Amirali;Özcan,Mutlu(2019).A review on
chemicalcomposition,mechanicalproperties,andmanufacturingworkowofadditivelymanufactured
currentpolymersforinterimdentalrestorations.JournalofEstheticandRestorativeDentistry,31(1):51-
57.
DOI:https://doi.org/10.1111/jerd.12438
1
TITLE
A review on chemical composition, mechanical properties and manufacturing work
flow of additively manufactured current polymers for interim dental restorations.
Marta Revilla-León DDS, MSD,a Matthew J. Meyers,b Amirali Zandinejad DDS, MSc,c
Mutlu Özcan DDS, DMD, PhDd
aAssistant Faculty and Assistant Program Director AEGD Residency, College of
Dentistry, Texas A&M University, Dallas, TX; Affiliate Faculty Graduate
Prosthodontics, School of Dentistry, University of Washington, Seattle, WA: and
researcher at Revilla Research Center, Madrid, Spain.
bStudent, College of Dentistry, Texas A&M University, Dallas, TX
cAssociate Professor and Program Director AEGD Residency, College of Dentistry,
Texas A&M University, Dallas, TX.
dProfessor and Head, Dental Materials Unit, Center for Dental and Oral Medicine,
University of Zürich, Switzerland.
2
ABSTRACT
OBJECTIVES: Additive manufacturing (AM) technologies can be used to fabricate 3D
printed interim dental restorations. The aim of this review is to report the manufacturing
workflow, its chemical composition, and the mechanical properties that may support their
clinical application.
OVERVIEW: These new 3D printing provisional materials are typically composed of
monomers based on acrylic esters or filled hybrid material. The most commonly used AM
methods to manufacture dental provisional restorations are stereolithography (SLA) and
material jetting (MJ) technologies. To the knowledge of the authors, there is no published
article that analyzes the chemical composition of these new 3D printing materials.
Because of protocol disparities, technology selected, and parameters of the printers and
material used, it is notably difficult to compare mechanical properties results obtained in
different studies.
CONCLUSIONS: Although there is a growing demand for these high-tech restorations,
additional information regarding the chemical composition and mechanical properties of
these new provisional printed materials is required.
Keywords: 3D printing, Additive manufacturing technologies, Interim restorations,
Material jetting, Stereolithography.
3
INTRODUCTION
ADDITIVE MANUFACTURING (AM) TECHNOLOGIES
Additive manufacturing (AM) technologies refer to the fabrication of an object layer-by-
layer.1 Advancements in AM technologies have allowed for its integration into the digital
workflow of prosthodontic applications. The American Section of the International
Association for Testing Materials (ASTM) international standard organization establishes
technical standards for a wide range of materials, products, systems, and services. The
ASTM committee F42 on AM technologies determined seven AM categories:
stereolithography (SLA), material jetting (MJ), material extrusion (ME) or fused
deposition modelling (FDM), binder jetting, powder bed fusion (PBF), sheet lamination,
and direct energy deposition.1-4 In dentistry, the most commonly used AM methods are
SLA and MJ technologies.
For SLA manufacturing, a building platform is immersed in liquid resin which is
then polymerized by an ultraviolet laser.5-7 The laser traces a cross-section of each layer.
After the layer is polymerized, the building platform descends by a distance equal to the
layer thickness, allowing uncured resin to cover the previous layer. This process is
repeated several times until the printed object is built.5-8 A scanning mirror directs a
precise laser beam at a reservoir of UV sensitive resin to cure the layer (Fig. 1). The depth
of cure, which ultimately determines the z-axis resolution, is controlled by the
photoinitiator and the irradiant exposure conditions (wavelength, power and exposure
time/velocity) as well as any dyes, pigments or other added UV absorbers.9-13
Digital Light Processing (DLP) is considered to be within the same AM category
as SLA technology by the ASTM because the technologies share many similarities.1,14
The primary distinction between the SLA and DLP is light source; the cross-sectional
image is created by either an arc lamp or semiconductor chip containing a matrix of
4
microscopic mirrors, the latter of which is referred to as a Digital Micromirror Device
(DMD). Each mirror represents one or more pixels in the projected image. The number
of mirrors corresponds to the resolution of the projected image.15 In safelight conditions,
light from the DLP projector passes through a UV transparent window and the image is
projected onto a vat of liquid photopolymer.15 In this system, the physical object is pulled
up from the liquid resin, rather than down and further into the liquid photopolymer. The
process is repeated until the 3D object is built.14,15
Material jetting technology is also referred to as Polyjet Printing (PP), in which a
liquid resin is selectively jetted out of hundreds of nozzles and polymerized with
ultraviolet light.9 The UV-curable polymers are applied only where desired for the virtual
design and, since multiple print nozzles can be used, the supporting material is co-
deposited. In addition, different variations in color or building material can be designated,
including spatially graded structures (Fig. 2).17,18
MANUFACTURING WORKFLOW
The digital workflow to manufacture a provisional restoration (Fig. 3) with a 3D printer
consists of the following sequence: data acquisition, data processing, and manufacturing
procedures.19
• Data acquisition involves digitization procedures normally performed by an
extraoral or intraoral scanning (IOS) device (Fig. 3AB), in which the patient’s
mouth or the working casts are converted into a standard tessellation language
(STL) file.
• Data processing involves the virtual design of the provisional restoration using
specific CAD software (Fig 3C). Due to the limitations of the AM manufacturing
process, specific parameters must be controlled during the digital design.
