How to Sterilize 3D Printed Objects for Surgical Use? An Evaluation of the Volumetric Deformation of 3D-Printed Genioplasty Guide in PLA and PETG after Sterilization by Low-Temperature Hydrogen Peroxide Gas Plasma

Abstract

Introduction
In the present time, there is rapid development in the application of 3D printing technology in surgery. One of the challenges encountered by the surgeon is the sterilization of these 3D-printed objects for use in the operating room.

Materials and Methods
Forty-two identical cutting guides used for genioplasty were 3D-printed: twenty-one in Polylactic acid (PLA) and twenty-one in Polyethylene terephthalate glycol (PETG). The guides were CT scanned after printing. They were then sterilized with the low-temperature hydrogen peroxide gas plasma technique (Sterrad®). A CT scan of the guides was also performed at T1 (after printing) and T2 (after sterilization). A software (Cloudcompare ®) was then used to accurately compare the volume of each guide at T0 (the initial computer-aided designed guide) vs T1 and T1 vs T2. Statistical analysis was then performed.

Results
Although there are differences that are statistically significant for each series between T0 and T2 and T1 and T2 for both PLA and PETG, this had no impact on the clinical use of sterilized objects using hydrogen peroxide sterilization technique because these morphological differences were minimal at less than 0.2mm.

Conclusion
Morphological deformations induced by the hydrogen peroxide sterilization are sub-millimeter and acceptable for surgical use. The hydrogen peroxide sterilization is, therefore, an alternative to avoid the deformation of 3D-printed objects made from PLA and PETG during conventional steam sterilization (autoclave). To the best of our knowledge, this is the first study regarding the morphologic deformation of 3D-printed objects in PLA and PETG after sterilization for medical use.

Full text

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410
DOI: 10.2174/1874210601913010410, 2019, 13, 410-417
The Open Dentistry Journal
Content list available at: https://opendentistryjournal.com
RESEARCH ARTICLE
How to Sterilize 3D Printed Objects for Surgical Use? An Evaluation of the
Volumetric Deformation of 3D-Printed Genioplasty Guide in PLA and PETG
after Sterilization by Low-Temperature Hydrogen Peroxide Gas Plasma
Olivier Oth1,*, César Dauchot1, Maria Orellana1 and Régine Glineur1
1Department of Oral and Maxillofacial Surgery, Hôpital Erasme, Université Libre de Bruxelles, Route de Lennik 808, 1070, Brussels, Belgium
Abstract:
Introduction:
In the present time, there is rapid development in the application of 3D printing technology in surgery. One of the challenges encountered by the
surgeon is the sterilization of these 3D-printed objects for use in the operating room.
Materials and Methods:
Forty-two identical cutting guides used for genioplasty were 3D-printed: twenty-one in Polylactic acid (PLA) and twenty-one in Polyethylene
terephthalate glycol (PETG). The guides were CT scanned after printing. They were then sterilized with the low-temperature hydrogen peroxide
gas plasma technique (Sterrad®). A CT scan of the guides was also performed at T1 (after printing) and T2 (after sterilization). A software
(Cloudcompare ®) was then used to accurately compare the volume of each guide at T0 (the initial computer-aided designed guide) vs T1 and T1
vs T2. Statistical analysis was then performed.
Results:
Although there are differences that are statistically significant for each series between T0 and T2 and T1 and T2 for both PLA and PETG, this had
no impact on the clinical use of sterilized objects using hydrogen peroxide sterilization technique because these morphological differences were
minimal at less than 0.2mm.
Conclusion:
Morphological deformations induced by the hydrogen peroxide sterilization are sub-millimeter and acceptable for surgical use. The hydrogen
peroxide sterilization is, therefore, an alternative to avoid the deformation of 3D-printed objects made from PLA and PETG during conventional
steam sterilization (autoclave). To the best of our knowledge, this is the first study regarding the morphologic deformation of 3D-printed objects in
PLA and PETG after sterilization for medical use.
Keywords: 3D printing, CADCAM, Additive manufacturing, Fused deposition modelling, Maxillofacial surgery, Orthognathic surgery,
Genioplasty, Polylactic acid, PLA, PETG, Polyethylene terephthalate glycol, Sterilization, Hydrogen peroxide gas plasma, Sterrad sterilization
system.
Article History Received: June 11, 2019 Revised: August 26, 2019 Accepted: October 20, 2019
1. INTRODUCTION
In the present time, there is a surge in the use of 3D
printing technology in surgery, especially in the area of cranio-
maxillofacial surgery. 3D printing, also known as rapid
prototyping and/or additive manufacturing, is becoming a
significant tool in maxillo facial surgery [1].
* Address correspondence to this author at the Department of Oral and
Maxillofacial Surgery, Hôpital Erasme, Université Libre de Bruxelles, Route de
Lennik 808, 1070, Brussels, Belgium: Tel: +32/2.555.31.11;
E-mail: oth.olivier@gmail.com
Examples of applications of 3D printing in cranio-maxillo-
facial surgery are: anatomical models for teaching purposes,
intraoperative visualization of the anatomical structures, anato-
mical models using the mirroring technique for pre-bending of
osteosynthesis material, and surgical guides used intra opera-
tively in implantology, orthognathic surgery, oncologic, and
reconstructive maxillofacial surgery.
There are two possibilities for a surgeon to use 3D printing
technologies in practice: Either to call upon outside firms to
deal with design and 3D printing, or to understand the design

How to Sterilize 3D Printed Objects for Surgical Use? The Open Dentistry Journal, 2019, Volume 13 411
and 3D printing within its hospital institution, aka “in-house
printing”, or “point of care manufacturing”. In both cases, the
surgeon is faced with the problem of sterilization of 3D-printed
objects, which is mandatory for their use in the operating room.
Sterilization can be performed by 2 types of recognized
methods [2]: 1) Thermal sterilization by dry heat or steam, aka
moist heat sterilization or autoclave; 2) Low-temperature
sterilization: chemical (with ethylene oxide or hydrogen
peroxide for example), or with radiation (ionizing or UV).
Our in-house 3D-printing medical department used a Fused
Deposition Modeling (FDM) 3D-printer. Thermoplastic
polymers are the most ideal printing materials for additive
manufacturing processes, such as FDM due to their low
melting temperature [3]. The problem with plastic bio-
materials such as Polylactic Acid (PLA) and Polyethylene
Terephthalate Glycol (PETG) is that they are sensitive to
conventional thermal steam sterilization techniques, including
the temperature of 121 degree Celsius and above with high
rates of humidity). These materials are deformed with this type
of sterilization.
Thermal sterilization by dry heat is no longer authorized in
the European Union. Ultraviolet light sterilization is a method
of sterilization based on the sensitivity of microorganisms to
get exposed to low wavelengths of ultraviolet light. This
method is used in research laboratories to prepare sterile
worktops, for the preservation of food, or the purification of air
or water. Ionizing radiation is used by medical equipment
companies and food decontamination [4]. The materials are
packaged and stored in a shipping container that is gamma
irradiated. Therefore, this method is not suitable for a 3D
printing laboratory in a healthcare institute.
Ethylene oxide leads to changes in the polymer structures,
provokes molecular weight loss and creates a toxic deposit on
the surface of the object. Ethylene oxide sterilization is thus not
recommended for PLA or PETG [5].
For all these reasons, the study was focused on hydrogen
peroxide low-temperature sterilization. This sterilization tech-
nique exploits the synergism between peroxide and low temp-
erature gas plasma to rapidly destroy microorganisms [6]. At
the completion of this sterilization process, no toxic residues
remain on the sterilized items. The technology is known to be
particularly suited to the sterilization of heat and moisture
sensitive instruments since process temperatures do not exceed
about 50°C and sterilization occurs in a low moisture environ-
ment. The efficacy of the process has been demonstrated
against a broad spectrum of microorganisms. This method has
advantages over ethylene oxide including sterilization of
safety, ease of maintenance and no requirement for aeration
time [7].
Many articles can be found related to the applications of
3D-printed devices in medicine, yet very few of them fully
describe the technique of disinfection/sterilization. Only two
articles were found focusing on the sterilization of 3D printed
objects [8, 9].
The referenced object chosen for this study is a cutting
guide used in orthognathic surgery to perform genioplasty.
Genioplasty is a widely used surgical technique to correct chin
deformity. It consists of an osteotomy of the inferior border of
the mandible allowing movement of the chin in three dimen-
sions and positioning it in its new desired position [10]. This
guide can aid the surgeon in not touching the surrounding
noble anatomical structures (dental roots, inferior alveolar
nerve) and guide his surgical gesture as he performs this
osteotomy.
The aim of this study was to investigate the morphological
effect of the hydrogen peroxide low-temperature sterilization
on surgical objects that are 3D-printed in PLA and PETG. The
reference object chosen for this study is a cutting-edge guide
used in orthognathic surgery to perform genioplasty. Genio-
plasty is a widely used surgical technique to correct chin
deformity.
2. METHODS
To investigate the effect of hydrogen peroxide, low-
temperature sterilization on surgical objects 3D-printed in PLA
and PETG, the following study was designed.
2.1. 3D Printing Process
The surgical guides are designed in the maxillofacial
department, with a protocol developed and optimized for
several years. Two series of 21 identical guides were printed:
one series was printed in PLA (makerbot® PLA filament 1.75
mm), and the other in PETG (taulman® 3D guidel!ne® filament
1.75 mm).
The 3D printer model is a Replicator+® (Makerbot Indus-
tries®, New York, USA) operating on the principle of additive
technology, Fused Deposit Modelling. Table 1 shows the
parameters of the 3D-printer used for each material. Table 2
shows the physical properties of the solidified form of PLA and
PETG.
Table 1. Range of process parameters of the 3D printer for PLA and PETG.
Parameters Range for PLA Parameters Range for PETG
Layer thickness (mm) 0.1 mm Layer thickness (mm) 0.3 mm
Nozzle diameter (mm) 0,5 mm Nozzle diameter (mm) 0,5 mm
Part Bed temperature (°C) not heated room temperature (15-25) Part Bed temperature (°C) not heated room temperature (15-25)
Extruder head speed 150 mm/sec Extruder head speed 150 mm/sec
Temperature of extruder (°C) 215 Temperature of extruder (°C) 215

412 The Open Dentistry Journal, 2019, Volume 13 Oth et al.
Table 2. Physical properties of solidified PLA and PETG.
Parameters Value of solidified PLA Parameters Value of solidified PETG
Grade 4043D Grade not available
Density (g/cm3) 1.24 Density (g/cm3) 1.27
Glass Transition Temperature (°C) 60 Glass Transition Temperature (°C) 77
Melting point (°C) 160 Melting point (°C) 100
2.2. Sterilization Process
STERRAD® 100S (Johnson & Johnson® company), a low-
temperature hydrogen peroxide sterilizer, with one short cycle
of 50 minutes with temperature always lower than 55 °C was
used to sterilize the guides.
2.3. Comparison and Validation Process: Morphological
Analysis
The morphology of the guide was compared 3 times: T0 =
the guide computer-designed in 3D before 3D printing (STL
file); T1 = the guide after 3D printing and before sterilization;
T2 = the guide after 3D printing and after low-temperature
hydrogen peroxide sterilization.
Before sterilization (T1), each series of guides in PLA and
PETG were scanned with a CT-scanner using a high-resolution
protocol with the following acquisition settings; system:
SOMATOM Emotion 16, tube current: 130 mAs, gray-scale:
16 bits, potential: 130 kV, scan time 35 s, voxel size: 0.01 mm3
(0.24 mm x 0.24 mm x 0.20 mm).
After sterilization (T2), each series was again scanned with
the same CT-scanner and with the same acquisition settings.
The DICOM images were exported and 3D Slicer®
software was used to segment the guide and create STL files
(the file extension used in 3D printing). Blender® software was
then used to isolate each guide of both series.
To compare the morphology of the guides, Cloud
Compare® program was used. The principle of this software is
to decompose an object, into a number (n) of points (voxel
points) and then compare the deviation of the points of the
reference guide with respect to the compared guide. 3D
designed reference guide (T0) was compared with the sterilized
guide (T2) and the printed non-sterilized guide (T1) with the
sterilized guide (T2) (Figs. 1-4).
2.4. Statistical Analysis
Once the data was collected, Student t-paired tests were
used to evaluate the differences in mean distances of the
reference 3D-designed guide (t0), and the post sterilization
guide (t2) and printed guide (t1) and sterilized guide (t2).
Random factor ANOVAs were used to test the differences in
morphometric means between 21 PLA guides and 21 PETG
guides. A p-value of less than 5% was considered significant.
Statistical analyses were performed with the R software
(version 3.5.1).
Fig. (1). (from left to right): Genioplasty guide designed in 3D (T0) –
3D-printed guide non-sterilized (T1) – Guide after sterilization (T2).
Fig. (2). Process of alignment of two scanned guide with the software Cloudcompare®.

How to Sterilize 3D Printed Objects for Surgical Use? The Open Dentistry Journal, 2019, Volume 13 413
Fig. (3). Comparison of 2 guides via the C2M function and extraction of the comparative data.
3. RESULTS
3.1. PLA T0 - T2 (Reference 3D-Designed Guide –
Sterilized Guide)
18 out of the 21 guides have a significant average
difference after the effect of printing and sterilization. In this
series, the largest difference in average is 0.147 mm between
the points of the guide. The ANOVA shows a significant
average difference between the guides (Table 3).
3.2. PLA T1 - T2 (Printed Guide – Sterilized Guide)
19 out of the 21 guides have a significant average
difference after the effect of sterilization. In this series, the
largest difference in average is 0.1887 mm between the points
of the guide. The ANOVA shows a significant average
difference between the guides (Table 4).
3.3. PETG T0-T2 (Reference 3D-Designed Guide – Sterilized
Guide)
Only 1 out of the 21 guides do not have a significant
average difference after the effect of printing and sterilization.
In this series, the largest difference in average is 0.1887 mm
between the points of the guide. The ANOVA shows a
significant average difference between the guides (Table 5).
3.4. PETG T1-T2 (Printed Guide – Sterilized Guide)
21 guides have a significant average difference after the
effect of printing. The largest difference in average is 0.0976
mm (Table 6).
Fig. (4). Example of histogram and Gauss curve of the deviation of the points of one guide at T2 compared to the referenced object (guide at T0)
obtained with CloudCompare®.
Gauss: mean = 0.024261 / std.dev. = 0.150409 [66 classes]
240
200
160
120
80
40
0
-0.3 -0.15 0 0.15 0.3 0.45 0.6
Temp. approx. distances
Count

414 The Open Dentistry Journal, 2019, Volume 13 Oth et al.
Table 3. PLA T0 - T2 (reference 3D-designed guide – sterilized guide).
Guide
ID nMean difference
t0-t2 SD P-value* Lower 95% CI Upper 95%
CI P-value**
1 4001 0,113 0,338 <0.001 0,1035 0,1243
<0.001
2 4033 0,147 0,218 <0.001 0,1402 0,1536
3 4350 0,094 0,369 <0.001 0,0845 0,1063
4 4097 0,126 0,298 <0.001 0,1184 0,1366
5 4178 0,096 0,379 <0.001 0,0870 0,1099
6 4240 0,058 0,440 <0.001 0,0472 0,0736
7 4186 0,123 0,338 <0.001 0,1156 0,1360
8 4177 0,068 0,424 <0.001 0,0574 0,0830
9 4122 0,115 0,327 <0.001 0,1062 0,1261
10 4307 0,111 0,359 <0.001 0,1015 0,1229
11 4501 0,118 0,374 <0.001 0,1081 0,1299
12 4203 0,101 0,346 <0.001 0,0934 0,1142
13 4617 0,041 0,480 <0.001 0,0282 0,0558
14 4323 0,077 0,421 <0.001 0,0652 0,0902
15 4452 -0,015 0,475 0,088 -0,0260 0,0018
16 4360 -0,007 0,484 0,435 -0,0200 0,0086
17 4386 -0,009 0,489 0,342 -0,0214 0,0074
18 4134 0,127 0,330 <0.001 0,1188 0,1388
19 4252 0,099 0,400 <0.001 0,0887 0,1127
20 4187 0,132 0,330 <0.001 0,1250 0,1449
21 4107 0,135 0,310 <0.001 0,1263 0,1452
*Paired t-test; **One way fixed factor ANOVA
Table 4. PLA T0 - T2 (reference 3D-designed guide – sterilized guide).
Guide
ID NMean difference
t1-t2 SD P-value* Lower 95% CI Upper 95% CI P-value**
1 4001 0,1887 0,1546 <0.001 0,184 0,194
<0.001
2 4033 0,0047 0,1360 0,026 0,001 0,009
3 4350 0,0255 0,1416 <0.001 0,022 0,030
4 4097 0,0014 0,1335 0,366 -0,002 0,006
5 4178 0,0341 0,1411 <0.001 0,031 0,039
6 4240 0,0242 0,1505 <0.001 0,020 0,029
7 4186 0,0221 0,1451 <0.001 0,019 0,028
8 4177 0,0307 0,1515 <0.001 0,027 0,036
9 4122 0,0296 0,1408 <0.001 0,026 0,035
10 4307 0,0161 0,1441 <0.001 0,012 0,021
11 4501 0,0147 0,1387 <0.001 0,011 0,019
12 4203 0,0051 0,1326 0,003 0,002 0,010
13 4617 0,0476 0,1581 <0.001 0,043 0,053
14 4323 0,0021 0,1410 0,2463 -0,002 0,007
15 4452 -0,0052 0,1472 0,045 -0,0001 -0,009
16 4360 0,0220 0,1379 <0.001 0,018 0,026
17 4386 0,0250 0,1422 <0.001 0,021 0,030
18 4134 0,0140 0,1427 <0.001 0,010 0,019
19 4252 0,0153 0,1516 <0.001 0,011 0,020
20 4187 0,0349 0,1417 <0.001 0,032 0,040
21 4107 0,0039 0,1426 0,047 0,0001 0,0087
*Paired t-test; **One way fixed factor ANOVA

How to Sterilize 3D Printed Objects for Surgical Use? The Open Dentistry Journal, 2019, Volume 13 415
Table 5. PETG T0-T2 (reference 3D-designed guide – sterilized guide).
Guide
ID NMean difference
t0-t2 DS Lower 95% CI Upper 95% CI P-value* P-value**
1 4130 0,1980 0,2660 0,1911 0,2073 <0.001
<0.001
2 4156 0,0039 0,4283 -0,0070 0,0189 0,3693
3 4277 0,1449 0,2787 0,1373 0,1539 <0.001
4 5208 0,1971 0,2566 0,1887 0,2026 <0.001
5 4130 0,1837 0,2570 0,1771 0,1927 <0.001
6 4092 0,1781 0,2659 0,1709 0,1871 <0.001
7 4114 0,1752 0,2488 0,1688 0,1839 <0.001
8 4336 0,1125 0,3221 0,1040 0,1231 <0.001
9 4197 0,1576 0,3322 0,1499 0,1699 <0.001
10 4132 0,1863 0,2194 0,1806 0,1939 <0.001
11 4165 0,1774 0,2715 0,1709 0,1874 <0.001
12 4196 0,1648 0,2873 0,1582 0,1755 <0.001
13 4512 0,1890 0,1724 0,1845 0,1945 <0.001
14 4372 0,1782 0,2151 0,1726 0,1853 <0.001
15 4216 0,1615 0,3124 0,1535 0,1723 <0.001
16 4102 0,1890 0,2225 0,1831 0,1966 <0.001
17 4193 0,1681 0,3056 0,1611 0,1796 <0.001
18 4081 0,1722 0,2564 0,1649 0,1806 <0.001
19 4133 0,1448 0,3218 0,1365 0,1560 <0.001
20 4115 0,1684 0,2730 0,1614 0,1780 <0.001
21 4113 0,1717 0,2667 0,1650 0,1812 <0.001
*Paired t-test; **One way fixed factor ANOVA
Table 6. PETG T0-T2 (reference 3D-designed guide – sterilized guide).
Guide
ID NMean difference
t1-t2 DS Lower 95% CI Upper 95% CI P-value* P-value**
1 4130 0,1055 0,1299 0,103 0,111 <0.001
<0.001
2 4156 -0,0116 0,1485 -0,015 -0,006 <0.001
3 4277 0,0352 0,1427 0,031 0,040 <0.001
4 5208 0,0846 0,1306 0,080 0,087 <0.001
5 4130 0,0727 0,1367 0,069 0,078 <0.001
6 4092 0,0576 0,1329 0,054 0,062 <0.001
7 4114 0,0651 0,1381 0,062 0,070 <0.001
8 4336 0,0088 0,1297 0,005 0,013 <0.001
9 4197 0,0672 0,1348 0,064 0,072 <0.001
10 4132 0,0798 0,1235 0,077 0,084 <0.001
11 4165 0,0500 0,1411 0,047 0,055 <0.001
12 4196 0,0541 0,1414 0,051 0,059 <0.001
13 4512 0,0868 0,1192 0,084 0,091 <0.001
14 4372 0,0582 0,1251 0,055 0,062 <0.001
15 4216 0,0827 0,1399 0,079 0,088 <0.001
16 4102 0,0906 0,1333 0,087 0,095 <0.001
17 4193 0,0976 0,1420 0,094 0,103 <0.001
18 4081 0,0743 0,1240 0,071 0,078 <0.001
19 4133 0,0808 0,1371 0,077 0,086 <0.001
20 4115 0,0776 0,1417 0,074 0,083 <0.001
21 4113 0,0767 0,1376 0,073 0,082 <0.001
*Paired t-test; **One way fixed factor ANOVA

416 The Open Dentistry Journal, 2019, Volume 13 Oth et al.
4. DISCUSSION
Very few papers have studied the sterilization of 3D-
printed objects. Kozakiewicz has studied the effect of sterili-
zation on paper-based 3D-printed solids [9]. Shaheen has
studied the effect of sterilization of objects printed with the
PolyJet technology (Stratasys, Eden Prairie, MN USA). Limit
to disinfection of the 3D-printed objects should be avoided in
all cases [8].
According to Bathia and Ramadurai [11], the material
released from an FDM 3D-printer is sterile since it leaves the
extruder at 220°C (well above the 121°C recommended for
steam sterilization). But contamination of the printing plate is
always possible and a totally sterile manipulation of the object
from 3D printing to the operating room cannot be guaranteed.
The use of a conventional sterilization technique and the
preservation of the sterilized object in a package provided for
this purpose are therefore necessary.
PLA and PETG are very common bio-materials in 3D-
desktop FDM-printer. Those materials do not bear high
temperature. This guide in PLA and PETG melted under a
short cycle of 5 minutes under 121°C with thermal steam
sterilization, making the use of autoclave impossible. This is
the reason why this technique of sterilization is not recomm-
ended. But this finding is inconsistent with the study of
Boursier et al. [12] who concluded that PLA printed-objects
with FDM 3D printer can be sterilized with an autoclave.
Boursier et al. scanned a cat’s femur after dissection, printed it,
sterilized it and compared its deformation with handly measu-
rements. This inconsistency could be explained by the fact that
Boursier et al. use a different 3D printer and a PLA from
another brand. PLA is a polymer composed of L-lactide and D-
lactide chains. The thermal and mechanical properties of PLA
depend on the ratio and distribution of L- and D-LA in the
polymer chains. The melting temperatures and the transition
glass temperature could thus vary from one brand to another.
Because the temperature of hydrogen peroxide sterilization
always stays lower than 55°C, this technique can be applied to
all subtypes of PLA.
No study about sterilization of PETG was found in the
literature. The use of PETG (taulman® 3D guidel!ne® filament
1.75 mm) for additive manufacturing in medical use should be
preferred because of its proven biocompatibility in accordance
with the industrial standard, its European ISO10993 certifi-
cation and its American FDA-approval [13].
The other sterilization techniques have significant
disadvantages. Thermal sterilization by dry heat is currently
prohibited in the hospitals of the European Union (because of
inactivity on prions). Radiation sterilization is used in the food
and medical device industry and its use is not suitable for
hospitals. Ethylene oxide should be avoided because it leads to
changes in the polymer structures, provokes molecular weight
loss and creates a toxic deposit on the surface of the object. In
comparison, with the hydrogen peroxide low-temperature
sterilization, no toxic residues remain on the sterilized items.
This technique is effective, safe and does not require aeration
time compared to ethylene oxide [7].
Regarding the results in morphology variations, although
there are differences that are statistically significant for each
series between T0 and T2 and T1 and T2 for both PLA and
PETG, this has no impact on the clinical use of sterilized
objects using hydrogen peroxide sterilization technology.
Indeed, these morphological differences are minimal and less
than 0.2 mm. Furthermore, these differences could also be
simply related to 3D reconstruction from scanners since their
degree of accuracy is equal to 0.4 mm or to the layer thickness
of the 3D printing or both. Considering these parameters, an
accuracy of 0.2 mm seems reasonable from a surgical stand-
point.
Therefore, the use of the hydrogen peroxide low-
temperature sterilization for sterilization of 3D printed objects
in PLA and PETG is strongly recommended.
Finally, in this study, a genioplasty guide was used as a
reference object but this sterilization technique can be
extrapolated to any other 3D printed object for medical
purposes. This technique has successfully been tested for the
sterilization of other medical objects (e.g.: the anatomical
model of mandible), and no deformation of the 3D-printed
object was observed after 3D printing and after sterilization.
CONCLUSION
Steam sterilization is not suitable for the PLA and PETG
3D-printing material, because other sterilization methods were
excluded for different reasons. And because sterilization is
mandatory for the use of 3D-printing medical objects in the
operating room, a study was conducted to evaluate the morpho-
logical effect of hydrogen peroxide sterilization on a surgical
genioplasty guide 3D-printed with PLA and PETG.
This one concludes that the morphological deformations
induced by the hydrogen peroxide sterilization are sub milli-
meter and compatible with surgical use. The hydrogen per-
oxide sterilization is, therefore, an alternative avoiding the
deformation of 3D-printed objects from PLA and PETG during
their sterilization with steam sterilization (autoclave).
To the best of our knowledge, this is the first study about
the morphologic deformation of 3D-printed objects in PLA and
PETG for medical use after sterilization.
LIST OF ABBREVIATIONS
FDM = Fused-Deposition-Modeling
PLA = Polylactic Acid
PETG = Polyethylene Perephthalate Glycol
L-LA = L-Lactide
D-LA = D-Lactide
ETHICS APPROVAL AND CONSENT TO
PARTICIPATE
This study received the approval of the Ethics Committee
of Erasme Hospital, Université Libre de Bruxelles, Brussels,
Belgium under the reference: SRB_201808_171.

How to Sterilize 3D Printed Objects for Surgical Use? The Open Dentistry Journal, 2019, Volume 13 417
HUMAN AND ANIMAL RIGHTS
No animals/humans were used in the study that are the
basis of this research.
CONSENT FOR PUBLICATION
Not applicable.
AVAILABILITY OF DATA AND MATERIAL
The data that support the findings of this study are
available from corresponding author ( O. Oth) upon reasonable
request.
FUNDING
Dr. Olivier Oth received a financial grant of the direction
Board of Erasme Hospital to conduct this study (Grant No.
2018/06).
CONFLICT OF INTEREST
The authors declare no conflict of interest, financial or
otherwise.
ACKNOWLEDGEMENTS
We sincerely thank Charline Maertens de Noordhout for
her help in producing statistical data. We also sincerely thank
Prof. Stéphane Louryan for his help in producing radiological
data.
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