UNIVERSIDADE ESTADUAL PAULISTA
“JÚLIO DE MESQUITA FILHO”
Instituto de Ciência e Tecnologia
Campus de São José dos Campos
SHORT COMMUNICATION DOI: https://doi.org/10.4322/bds.2024.e4416
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Braz Dent Sci 2024 July/Sept;27 (3): e4416
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Surface hardness evaluation of a 3D printable resin designed for
final restorations
Avaliação da dureza superficial de uma resina para impressora 3D destinada para restaurações finais
Bruno Trivellato RODRIGUES1 , Selene Paiva PARAGUASSU2 , Dora Isabel de Sousa Martins FREITAS2 ,
Sérgio Kiyoshi ISHIKIRIAMA2 , Rafael Massunari MAENOSONO1
1 - Centro Universitário de Santa Fé do Sul, Departamento de Materiais Odontológicos, Santa Fé do Sul, SP, Brazil
2 - Universidade de São Paulo, Faculdade de Odontologia de Bauru, Departamento de Dentística, Endodontia e Materiais Odontológicos, Bauru,
SP, Brazil
How to cite: Rodrigues BT, Paraguassu SP, Freitas DISM, Ishikiriama SK, Maenosono RM. Surface hardness evaluation of a 3D printable
resin designed for nal restorations. Braz Dent Sci. 2024;27(3):e4416. https://doi.org/10.4322/bds.2024.e4416
ABSTRACT
Objective: Advancements in the digital area have triggered signicant interest among researchers in recent years,
particularly concerning 3D printers. In dentistry, 3D printers are already employed to create dental models,
surgical guides, and provisional restorations. Recently, a new 3D printable resin has been introduced with the
aim of being used for nal restorations (BioCrown, Makertech Labs). Despite its innovative nature, there is
considerable interest in the physical and mechanical properties of this new class of material. This study aimed
to evaluate the surface hardness of this new resin, comparing it to well-known materials such as acrylic resin
for provisional restorations (Triunfo Dent’s, Triunfo), conventional composite resin for nal restorations (Z250,
3M ESPE), and 3D printable resin for provisional restorations (BioProv, Makertech Labs). Methods: Knoop
microhardness testing was conducted (n = 10), and data were analyzed using the Kruskall-Wallis test, followed
by the Dwass-Steel-Critchlow-Fligner test for individual comparisons (p < 0.05). Results: Higher hardness values
(kgf/mm2) were observed for BioCrown (17.4 ± 2.5) compared to the conventional acrylic resin group (14.5 ±
1.5), but no differences were found for BioProv (17.8 ± 1.5). The conventional composite resin group obtained
the highest hardness values (81.3 ± 5.4). Conclusion: It can be concluded that the new 3D printable resins
for nal restorations exhibit low hardness levels, which may indicate inferior performance as nal restorations,
especially when compared to conventional composite resins. Further studies are necessary to comprehend and
enhance the mechanical properties of 3D printable resins.
KEYWORDS
Bioprinting; Composite resins; Permanent dental restoration; Hardness tests; Three-dimensional printing.
RESUMO
Objetivos: Avanços na área digital têm despertado um interesse signicativo entre os pesquisadores nos últimos
anos, particularmente quanto às impressoras 3D. Na odontologia, impressoras 3D já são utilizadas para criar
modelos dentários, guias cirúrgicos e restaurações provisórias. Recentemente, uma nova resina para impressora
3D foi introduzida com o objetivo de ser utilizada em restaurações nais (BioCrown, Makertech Labs). Apesar
da sua natureza inovadora, existe um interesse considerável nas propriedades físicas e mecânicas desta nova
classe de materiais. Este estudo teve como objetivo avaliar a dureza supercial desta nova resina, comparando
com materiais já conhecidos como resina acrílica para restaurações provisórias (Triunfo Dent’s, Triunfo), resina
composta convencional para restaurações nais (Z250, 3M ESPE) e resina para impressora 3D para restaurações
provisórias (BioProv, Makertech Labs). Metodos: Foi realizado teste de microdureza Knoop (n = 10) e os dados
foram analisados pelo teste Kruskall-Wallis, seguido do teste Dwass-Steel-Critchlow-Fligner para comparações
individuais (p < 0,05). Resultados: Valores de dureza (kgf/mm2) maiores foram observados para BioCrown
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Braz Dent Sci 2024 July/Sept;27 (3): e4416
Rodrigues BT et al.
Surface hardness e v a luation of a 3D printable r esin designed fo r final r estor ations
Rodrigues BT et al. Surface hardness evaluation of a 3D printable resin designed
for final restorations
INTRODUCTION
The advent of additive manufacturing,
more commonly known as 3D printing, has
opened up new possibilities within dentistry,
drawing attention from both the industry and
the scientic community. Currently, 3D printers
are being efciently used for the production of
dental models [1], surgical guides [2], complete
dentures [3], and temporary restorations [4].
Recently, a new 3D printable resin has been
introduced to be used as a nal restoration material
(BioCrown, Makertech Labs, São Paulo, Brazil).
According to the manufacturer, the incorporation
of zirconia and silanized ceramics has provided
greater strength, allowing it to be used as nal
restorations such as total crowns, inlays, and onlays.
It is noteworthy that other materials currently used
for the same purpose have signicantly higher costs
compared to 3D printable resins, becoming an
interesting alternative to reduce the cost of aesthetic
and functional rehabilitation.
Despite the significant technological
innovation, there is considerable interest
regarding the physical and mechanical properties
of this new group of resins. It is known that
resinous materials, in general, exhibit lower wear
resistance, greater pigmentation, color changes,
and loss of gloss and smoothness more quickly
when compared to human enamel or dental
ceramics [5-8]. In recent decades, microhybrid,
nanohybrid, and nanoparticulate composite
resins have shown improvements in their physical
and mechanical properties and are currently
considered satisfactory for restorations in both
anterior and posterior teeth [9].
Since few investigations are available for
this new 3D printable resin proposed for the
fabrication of nal restorations, the objective of
this study was to evaluate the surface hardness of
this new material using the Knoop microhardness
test, comparing the values with other commonly
used materials in dentistry.
MATERIAL & METHODS
This in vitro study presents an experimental
design with one variable (material), divided into
four levels: resin for nal restoration fabricated
with 3D printer (BioCrown), resin for provisional
restoration fabricated with 3D printer (BioProv),
conventional resin for nal restoration (Z250),
and conventional resin for provisional restoration
(Acrylic) (Table I). The response variable was
the material hardness (kgf/mm2), determined
through the Knoop microhardness test. Forty
specimens were fabricated, with 10 specimens
per group (n=10).
Fabrication of specimens
➢ Resin for final restoration in 3D printer
(BioCrown):
Disks with a diameter of 10 mm and thickness
of 2 mm were designed in Meshmixer software
(Autodesk Inc.), generating a .STL le, which was
prepared for printing using the Photon Workshop
V. 2.2 slicing software (Anycubic 3D Printing,
Shenzhen, China). Exposure parameters are
described in Table II.
Once the sliced le was prepared, it was
transferred to the Photon Mono 4k 3D printer
(Anycubic 3D Printing, Shenzhen, China), loaded
with Prizma 3D BioCrown resin (Makertech
Labs, São Paulo, Brazil). Ten specimens were
produced in each printing cycle. After completing
the cycle, specimens were removed from the
platform, and immersed in isopropyl alcohol
(Steenifer Soluções Químicas, Itupeva, Brazil)
in the Wash and Cure 2.0 device (Anycubic 3D
Printing, Shenzhen, China), with a 5-minute
cycle. Post-curing was performed on the same
device for 60 minutes. Subsequently, specimens
were polished using 600, 1200, and 2400 grit
water sandpapers (Buehler LTD, Lake Bluff, USA)
on a metallographic polisher (PL02E, Teclago,
Vargem Grande Paulista, Brazil).
(17,4 ± 2,5) em comparação ao grupo de resina acrílica convencional (14,5 ± 1,5), mas não foram encontradas
diferenças para BioProv (17,8 ± 1,5). O grupo de resina composta convencional obteve os maiores valores de
dureza (81,3 ± 5,4). Conclusao: Pode-se concluir que as novas resinas para impressora 3D indicadas para
restaurações nais apresentam baixos níveis de dureza, o que pode indicar desempenho inferior como restaurações
nais, principalmente quando comparadas às resinas compostas convencionais. Mais estudos são necessários
para compreender e aprimorar as propriedades mecânicas das resinas para impressora 3D.
PALAVRAS-CHAVE
Bioimpressão; Resinas compostas; Restauração dentária permanente; Testes de dureza; Impressão tridimensional.
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Braz Dent Sci 2024 July/Sept;27 (3): e4416
Rodrigues BT et al.
Surface hardness e v a luation of a 3D printable r esin designed fo r final r estor ations
Rodrigues BT et al. Surface hardness evaluation of a 3D printable resin designed
for final restorations
➢ Resin for provisional restoration in 3D
printer (BioProv):
The fabrication of specimens in this group
was carried out using the same parameters as the
BioCrown group, employing Prizma BioProv resin
(Makertech Labs, São Paulo, Brazil).
➢ Conventional resin for nal restoration (Z250):
An additional disk from the 3D resin group
was used to create a mold with addition silicone
(Ivoclar Vivadent, Schaan, Liechtenstein).
The disk was placed on a glass plate, and
heavy silicone was used to replicate the 10 mm
diameter and 2 mm thickness disk. After the mold
polymerized, it was removed, and its interior
was filled with Filtek Z250 resin (3M ESPE,
St. Paul, USA) using a spatula. The resin was
compressed by a glass plate against the mold,
and photoactivation was performed using a light-
curing unit (Kavo, Biberach, Germany) for 40 s.
After 7 days the specimen underwent the same
nishing and polishing sequence described for
the other groups.
➢ Conventional resin for provisional restoration
(Acrylic):
The same silicone mold was used for the
fabrication of specimens in this group. Acrylic
resin was handled following the manufacturer’s
instructions, in a 3:1 ratio. After obtaining a
homogeneous material, it was placed on the
mold and then compressed with a glass plate.
After 10 minutes the specimens were removed
and subsequently polished as described for the
other groups.
Knoop microhardness test
After polishing, the Knoop microhardness
test was performed on Buehler Omnimet
(Dusseldorf, Germany). Prepared specimens
were positioned under the diamond tip, which
made three indentations spaced 100 µm apart,
at a force of 0.49 N for 15 s. The Knoop hardness
calculation was based on the formula: KNH =
14228 x c / d2, where “c” is the load in gram-
force, and “d” is the length of the longest
diagonal.
Statistical analysis
The obtained values were assessed using
the Shapiro-Wilks normality test. As one of the
groups did not show a normal distribution, the
non-parametric Kruskall-Wallis test was chosen,
followed by the Dwass-Steel-Critchlow-Fligner
test for individual comparisons (p ≤ 0.05).
RESULTS
The mean hardness values± standard
deviation and differences between groups are
described in Table III. The acrylic resin group
exhibited the lowest hardness values. The 3D
printer resins, BioProv and BioCrown, showed
similar surface hardness, with both groups
having values higher than the acrylic resin group.
Conventional composite resins demonstrated
surface hardness values superior to all other
tested groups.
Table I - Groups, materials, and composition
Group Product Composition*
BioCrown BioCrown Prizma
(Makertech Labs, São Paulo, Brazil) Monomers, Oligomers, Photoinitiators, Pigments, Stabilizers.
BioProv BioProv Prizma
(Makertech Labs, São Paulo, Brazil) Monomers, Oligomers, Photoinitiators, Pigments, Stabilizers.
Z250 Composite Resin Filtek Z250
(3M ESPE, St. Paul, USA)
Treated silanized ceramic, Bisphenol A diglycidyl ether dimethacrylate (BisGMA),
Bisphenol A polyethylene glycol diether dimethacrylate (BISEMA-6), Diurethane
dimethacrylate (UDMA), Treated silica, Triethylene glycol dimethacrylate (TEGDMA)
Acrylic Resin Acrylic Resin Triunfo Dent’s
(Triunfo, Pirassinunga, Brazil)
Powder: Polymethylmethacrylate, Polypropylene and Pigments
Liquid: Methylmethacrylate Monomer, DMT and Inhibitor
*information provided by the manufacturer.
Table II - Exposure parameters used in the Photon Workshop V. 2.2
slicing software (Anycubic 3D Printing)
Parameter Prizma
BioCrown
Prizma
BioProv
Layer thickness 0.05 s 0.05 s
Normal exposure time 3.5 s 3.5 s
Off time 1.0 s 1.0 s
Bottom exposure time 60 s 60 s
Bottom layers 8 8
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Braz Dent Sci 2024 July/Sept;27 (3): e4416
Rodrigues BT et al.
Surface hardness e v a luation of a 3D printable r esin designed fo r final r estor ations
Rodrigues BT et al. Surface hardness evaluation of a 3D printable resin designed
for final restorations
Discussion
Understanding the physical and mechanical
properties of restorative materials allows for
predicting their clinical behavior, using faster and
more cost-effective tests compared to randomized
controlled clinical trials. While the latter provides
a higher level of scientic evidence, they require
more time and cost and should be conducted after
preliminary laboratory trials [10].
In the context of resin-based restorative
materials, one crucial aspect to study is clinical
wear, especially because past composite
resins exhibited low wear resistance and
were contraindicated in areas of significant
masticatory stress [11]. The incorporation of
hybrid, microhybrid, and nanoparticulate llers
has signicantly increased the wear resistance
of composite resins. Despite still having wear
resistance lower than dental enamel and dental
ceramics, current composite resins demonstrate
satisfactory clinical performance, being suitable
for both anterior and posterior teeth [12,13].
The emergence of new resin-based restorative
materials, such as 3D-printed resins, triggers great
interest in understanding their properties before
clinical use. Various laboratory test models can
be employed to evaluate wear resistance, such as
wear analysis through prolometry after simulated
brushing [14], wear analysis through two- or three-
body wear [15], and microhardness analysis [16].
In this study, the microhardness test was
chosen as it is a simpler and more cost-effective
test compared to others, as it does not require
cycling materials for wear assessment. Although
not directly assessing wear, the microhardness
test shows a signicant correlation with wear
(r = -0.91), as observed by Say
et al
., 2003 [16].
Regarding the obtained results, acrylic resins
exhibited the lowest hardness values among
the tested materials. Simoneti
et al
., 2022 [17]
observed very similar surface hardness values
for this material group, aligning with its clinical
indication for use in provisional restorations.
The BioProv and BioCrown groups did not
differ from each other. Both showed surface
hardness values higher than those of the acrylic
resin group. Castro
et al
., 2022 [18] evaluated
BioProv resin and obtained surface hardness
values similar to those found in this study.
In a scanning electron microscopy (SEM)
analysis, the authors observed only small ller
particles (likely composed of silica), which could
explain the higher hardness values compared to
acrylic resin. It is essential to note that BioProv
resin is recommended by the manufacturer for
provisional restorations.
Until now, no other studies have evaluated
BioCrown resin. However, initial analysis suggests
that its wear resistance might be compromised,
given its hardness values similar to BioProv
resin and signicantly lower than conventional
composite resins (Z250). Conventional composite
resins (Z250) demonstrated hardness values
four to five times higher than the 3D printer
resin groups. Sahadi
et al
., 2021 [19] observed
similar data, supporting the observation that
composite resins remain an excellent choice for
the restoration of both anterior and posterior teeth.
This study has limitations. As a single
laboratory test was performed, further studies
are potentially necessary to better understand
the properties of this new material group.
Additional laboratory tests evaluating wear and
SEM analysis for a better understanding of the
type of ller particles incorporated are suggested.
CONCLUSION
Based on the data obtained in this study, it
can be concluded that BioCrown resin, proposed
for nal restorations, shows surface hardness
values higher than acrylic resin, similar to 3D
printable resins recommended for provisional
restorations, and four to ve times lower than
conventional composite resins.
Author’s Contributions
BTR: Methodology, Formal Analysis,
Validation. SPP: Methodology, Formal Analysis.
DISMF: Methodology, Formal Analysis.
SKI: Resources, Funding Acquisition. RMM:
Table III - Mean values ± standard deviation of Knoop hardness observed in each group
BioCrown BioProv Z250 Acrylic
(kgf/mm2)T17.4 ± 2.5 B 17.8 ± 1.5 B 81.3 ± 5.4 C 14.0 ± 1.5 A
*Different capital letters represent differences between groups (p<0.05).
5
Braz Dent Sci 2024 July/Sept;27 (3): e4416
Rodrigues BT et al.
Surface hardness e v a luation of a 3D printable r esin designed fo r final r estor ations
Rodrigues BT et al. Surface hardness evaluation of a 3D printable resin designed
for final restorations
Conceptualization, Writing – Review & Editing,
Visualization, Supervision, Project Administration
and Funding Acquisition.
Conict of Interest
The authors have no proprietary, nancial,
or other personal interest of any nature or kind
in any product, service, and/or company that is
presented in this article.
Funding
This study was partially supported by
Programa Pesquisador Docente (PPD)
provided
by the University Center of Santa Fé do Sul
(UNIFUNEC).
Regulatory Statement
Not applicable.
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Rafael Massunari Maenosono
(Corresponding address)
Centro Universitário de Santa Fé do Sul, Departamento de Materiais
Odontológicos, Santa Fé do Sul, SP, Brazil.
Email: rafamaenosono@hotmail.com
Date submitted: 2024 June 21
Accept submission: 2024 July 22
