S. @ARKOVI] GJURIN et al.: CHARACTERIZATION OF NEW AND RETRIEVED TITANIUM BIOMATERIAL ...
33–37
CHARACTERIZATION OF NEW AND RETRIEVED TITANIUM
BIOMATERIAL FOR DENTAL IMPLANTS
KARAKTERIZACIJA BIOMATERIALOV NOVIH IN
UPORABLJENIH ZOBNIH VSADKOV
Sonja @arkovi} Gjurin
1*
, Monika Jenko
2
, ^rtomir Donik
2
, ^edomir Oblak
1
1
Department of Prosthodontics, Faculty of Medicine, University of Ljubljana, Slovenia, Vrazov trg 2,
1000 Ljubljana, Slovenia
2
Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana, Slovenia
Prejem rokopisa – received: 2020-06-09; sprejem za objavo – accepted for publication: 2020-07-25
doi:10.17222/mit.2020.114
Dental implants serve as a reliable treatment option for replacing missing teeth. The important properties for implant materials
are, besides biocompatibility, adequate strength, corrosion, wear and fracture resistance. The most important step in the stability
of the implant is a structural and functional connection between the implant’s surface and the newly formed bone, which is
called osseointegration. It comprises a cascade of complex physiological mechanisms. The implant’s surface characteristics and
roughness are the most important in achieving the biomechanical concept of secondary stability. Nowadays, dental implants are
produced from metals, ceramics or even polymers. Rehabilitations with titanium and titanium-alloy dental implants have shown
long-term survival; therefore, they have become a gold standard to replace missing teeth. In the study we investigated new and
retrieved dental implants and restorative materials, commercially pure titanium (cpTi), the Ti6Al4V alloy and CoCrMo alloys
using light microscopy and scanning electron microscopy for the surface morphology and microstructure. Energy-dispersive
spectroscopy was used for the chemical analyses. The results showed that the surfaces of the Ti and Ti6Al4V implants were
roughened by corundum (Al2O3) blasting, and the corundum contamination was found not only on the surface but also in the
sub-surface of the new and retrieved dental implants. It is assumed that the retained corundum Al2O3 contamination on the sur-
face of the Ti or Ti-alloy affects the osseointegration and longevity of the dental-implant rehabilitation.
Keywords: dental implant, corundum Al2O3, osseointegration, scanning electron microscopy, energy-dispersive X-ray spectros-
copy
Zobni vsadki slu`ijo kot zanesljiva metoda nadomestitve manjkajo~ih zob. Pomembne lastnosti materialov za zobne vsadke so
biokompatibilnost, upogibna trdnost ter korozijska in obrabna odpornost. Stabilnost vsadka v kosti je omogo~ena zaradi procesa
oseointegracije, ki pomeni strukturno in funkcionalno povezavo med povr{ino vsadka in novonastalo kostjo. Oseointegracija
poteka preko kaskade zapletenih fiziolo{kih mehanizmov. Stabilnost zobnega vsadka je odvisna od povr{inske lastnosti in
hrapavosti vsadka, kar zagotavlja dobro stabilnost v ~eljustni kosti. Sodobni zobni vsadki so izdelani iz kovin, keramike ali celo
polimerov. Zobni vsadki iz titana in njegove zlitine, predstavljajo zanesljivo oskrbo manjkajo~ih zob z visoko stopnjo pre`ivetja.
V {tudiji smo preiskovali nove in odstranjene zobne vsadke ter material za proteti~no oskrbo, izdelane iz komercialno ~istega
titana - cpTi, zlitine Ti6Al4V in CoCrMo z metodami svetlobne mikroskopije, vrsti~ne elektronske mikroskopije za povr{insko
morfologijo in mikrostrukturo ter energijske rentgenske disperzijske spektroskopije za kemijsko analizo. Rezultati prikazujejo
delce korunda (Al2O3) na povr{ini titanovih vsadkov in vsadkov iz zlitine Ti6Al4V. Sledi kontaminacije s korundom so bile
ugotovljene tudi v materialu pod povr{ino novih in odstranjenih zobnih vsadkov. Korund na povr{ini zlitine titanovih zobnih
vsadkov lahko vpliva na proces oseointegracije in zmanj{a `ivljensko dobo zobnih vsadkov.
Klju~ne besede: zobni vsadek, korund Al2O3, oseointegracija, vrsti~na elektronska mikroskopija, energijska rentgenska
disperzijska spektroskopija
1 INTRODUCTION
An implant is defined as a biomaterial that is inserted
either partially or completely into the body for therapeu-
tic, diagnostic or prosthetic purposes.
1
Dental implants
have been widely used for the oral rehabilitation of par-
tially or fully edentulous patients, as they serve as re-
placements for the roots of missing natural teeth.
1
The
surface property of dental implants has been identified as
the leading factor that influences the osseointegration of
an implant and therefore the success and longevity of the
implant.
1,2
Nowadays, 1300 different dental implant systems ex-
ist, varying in shape, dimensions, bulk and surface mate-
rials, thread design, implant-abutment connection, sur-
face topography, surface chemistry, wettability and
surface modification.
3
In general, the long-term survival
rate of titanium dental implants is excellent; however,
implant failures still occur.
3
Due to insufficient osseo-
integration within the first few months, primary implant
failure occurs in 1–2 % of patients.
3
In about5%ofpa -
tients, secondary implant failure develops several years
after successful osseointegration, commonly caused by
peri-implantitis.
3
Once a dental implant is produced, it is cleaned and
polished, followed by roughening of the surface via one
or more modification techniques.
1
Sandblasting is the
most common and basic treatment technique used for the
Materiali in tehnologije / Materials and technology 55 (2021) 1, 33–37 33
UDK 67.017:616-77:-616.314-77 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 55(1)33(2021)
*Corresponding author's e-mail:
sonja.zarkovic@mf.uni-lj.si (Sonja @arkovi~ Gjurin)

modification of a surface.
1
Sprayed corundum particles
can create deep crevices and an average profile rough-
ness of 1–2 μm.
3
This range of microtopography seems
to provide an optimal degree of roughness to promote
excellent osseointegration.
4
Osseointegration consists of
a cascade of complex physiological mechanisms, which
are similar to direct fracture healing.
3
The surface topog-
raphy of an implant is crucial for the adhesion and differ-
entiation of osteoblasts during the osseointegration.
3
The
study of different surface treatments has been well docu-
mented in the literature; therefore, the presence of resid-
uals of alumina embedded on the surface of a dental im-
plant is regarded as a potential risk for long-term
osseointegration.
5
The aims of the present study were:
(I) a detailed surface characterization is required for a
better understanding and exploitation of the surface
properties of dental implants;
(II) the microstructure of dental implants is a neglected
factor in implant design; and
(III) a detailed microstructure characterization of prema-
turely failed dental implants.
2 EXPERIMENTAL PART
2.1 Materials and methods
The two retrieved dental implants (sample 1 and sam-
ple 2) were selected from revision procedures performed
at the Department for Prosthetic Dentistry, Medical Fac-
ulty, University of Ljubljana. We also investigated two
new dental implants (sample 3 and sample 4) of the pro-
ducer Ankylos Friadent, Dentsply Sirona for compari-
son.
The surfaces of the new and retrieved dental implants
were examined.
All the retrieved dental implants were sent for
sonication in Ringer’s solution for microbiological anal-
ysis and afterwards for cleaning and sterilization. Next,
they were dried and stored in steam-sterilized paper
bags. All the retrieved dental implants were cleaned ac-
cording to standard procedures at the Microbiology De-
partment of the Medical Faculty, University of Ljubljana,
which consists of immersion in 2 % micro-soap solution,
followed by acetone, isopropanol (xN), 95 % ethanol
(xN), and deionized water (xN); (xN) is the number of
repeated processes. Sterilization was performed by
autoclaving according to a standard protocol at 120 °C
and a pressure of 1.25 bar for 20 min. Afterwards, they
were dried and stored in serialized bags and kept in a dry
place.
Samples for the bulk and surface microstructure anal-
yses and for the surface-chemistry analyses were pre-
pared by standard metallographic procedures. Samples
for the bulk and surface microstructure characterizations
of cpTi (commercially pure Ti), the Ti6Al4V alloy and
the CoCrMo were cut from the new and retrieved dental
implants using a water-cutting machine. Samples were
ground and polished using Struers devices (Ballerup,
Denmark).
2.2 Scanning electron microscopy (SEM) analysis
The cross-sections of the new and used dental im-
plants were recorded with a Tagarno FHD Trend digital
microscope at low magnifications. For the morphology,
microstructure and chemistry the samples were analyzed
using a field-emission scanning electron microscope
(ZEISS crossbeam 550 FIB-SEM, Carl Zeiss AG, Ober-
kochen, Germany). The instrument is equipped with sec-
ondary-electron (SE) and backscattered-electron (BE)
imaging modes for analyses of the morphology of the
samples and EDS (EDAX, Octane Elite, Draper, Cam-
bridge, MA, USA) for analyzing the surface chemistry.
For the SE and BE imaging an acceleration of 15 kV at a
current of approximately 2.0 nA was used for a vacuum
in the main chamber below 10
–6
mbar. Energy-dispersive
x-ray spectroscopy (EDS) and EDS mapping were used
for the elemental analyses of the surface (Octane Elite
EDS System EDAX).
3 RESULTS
3.1 Scanning electron microscopy (SEM)
The surfaces of the Ti and Ti6Al4V implants were
roughened by sandblasting using corundum (Al
2
O
3
). On
the retrieved implants (sample 1 and sample 2) Al
2
O
3
contamination was detected. The new implant (sample 3)
retained no Al
2
O
3
contamination. Contamination with
S. @ARKOVI] GJURIN et al.: CHARACTERIZATION OF NEW AND RETRIEVED TITANIUM BIOMATERIAL ...
34 Materiali in tehnologije / Materials and technology 55 (2021) 1, 33–37
Figure 1: Cross-section of retrieved implant (sample 1) and retrieved
dental implant with metal implant abutment and metal ceramic crown
(sample 2) recorded with digital microscope Tagarno FHD Trend

Al
2
O
3
was found not only on the surface but also in the
bulk of the implant, close to the surface of the retrieved
dental implant. Figure 1 showed a cross-section of
retrieved implants (a) and a cross-section of the implant
restored with the Ti6Al4V screw, CoCrMo abutment and
cemented Co Cr metal ceramic crown.
Additional SE images (Figures 3 and 6) with EDS
area analyses (Figure 6) and EDS mappings (Figures 4
and 5) were performed with a scanning electron micro-
scope for an elemental distribution of the implant’s
cross-section.
Figure 3 reveals the embedding of the corundum
contamination in the size of a few tens of microns below
the surface observed on different areas of the new dental
implant in the cross-section.
Figure 4 represents the mapping of the cross-section
to corroborate the surface and sub-surface contamination
with Al and O (Al
2
O
3
) after the surface treatment.
On the other hand, Figure 5 shows the EDS mapping
of the CoCr alloy abutment with porcelain fused to metal
crown on the top with the elemental distribution of the
Ti, Co, and Cr elements. Images on Figure 5 represent
S. @ARKOVI] GJURIN et al.: CHARACTERIZATION OF NEW AND RETRIEVED TITANIUM BIOMATERIAL ...
Materiali in tehnologije / Materials and technology 55 (2021) 1, 33–37 35
Figure 5: SEM/EDS mapping of: a) retrieved integrated implant,
CoCrMo abutment and ceramic crown, sample 2, b) SE of cross-sec-
tion, detail of SE image, c) shows CoCrMo microstructure; d)
SEM/EDS mapping of retrieved dental implant 2, distribution of ele-
ments show e) Ti (green), f) Cr (brown) and g) Co (blue).
Figure 3: SE image of the cross-section of a new dental implant (sam-
ple 1), surface and sub-surface corundum contamination (darker grey,
arrow pointing) was found at different magnifications, darker grey ar-
eas are retained corundum particles from the blasting procedure of the
surface.
Figure 4: SEM/EDS mapping of a cross-section of the new dental im-
plant sample: a) SE image, b) EDS mapping showing the distribution
of elements Ti (red) and Al
2
O
3
(blue), c) Ti matrix (light green), d) Al
(light blue) and e) O
2
(green)
Figure 2: Cross-section of new and retrieved dental implant (sample
3) at two different magnifications recorded with digital microscope
Tagarno FHD Trend.

an integrated implant with a stereo microscope Figure
5a, while Figures 5b to 5g shows the microstructure
with SEM and EDS mapping of smaller area on the sur-
face of the CoCr alloy. Figures 5f and 5g show the
evenly distributed Co and Cr and that Ti is not in touch
with the CoCr alloy in the middle since the ceramic sep-
arates the CoCr alloy and the Ti.
Figure 6 reveals the SE image of the cross-section of
a different surface of the implant. Figure 6a represents
the screw joint of cp Ti and TiAlV alloy – which is rep-
resented in Figure 6c and the spectra in Figure 6d. Fig-
ure 6b reveals the microstructure of the TiAlV alloy,
while Figures 6e and 6f represent the cross-section with
no additional Al
2
O
3
contamination on either surface or
subsurface areas as was observed in Figures 3 and 4.
4 DISCUSSION
The presented results showed that the surfaces of the
Ti and Ti6Al4V implants were roughened by Al
2
O
3
blasting, and the surface contamination with Al
2
O
3
resi-
due was found not only on the surface but also in the
subsurface of the retrieved dental implant. Sandblasting
is a necessary step in the surface preparation of dental
implants, as a simple and basic method that accelerates
the osteoblast attachment and propagates the osseo-
integration, thus improving the initial stability.
1,5
The
surface composition and the implant biocompatibility
can be changed by blasting the implants’ surface with
gritting agents made of materials other than the dental
implant core material.
5
Sandblasting changes the structure and also the sur-
face chemistry, increases the wettability and the potential
for early interaction of the dental implant surface with
biological fluids.
1
If the sand particles after sandblasting
are not completely removed from the implant body, they
can cause inflammation
1
As observed from the SE im-
ages and SEM/EDS mappings, the Al
2
O
3
residue is still
present on the surface and just below the implant surface,
which could also be a potential initiation point for corro-
sion. After sandblasting of the surface, it is of great im-
portance for the Al
2
O
3
residue to be removed before the
implantation in the bone.
The configuration and conformation of cellular
pseudopodi are important in cell adhesion, which seems
to be enhanced by the surface roughness.
6
Additionally,
cells on the rougher surfaces release higher levels of fac-
tors, which are involved in the regulation of the bone for-
mation.
6
Therefore, it is not surprising that there was sig-
nificantly less coronal bone loss around the sandblasted
dental implants, which could be the result of the better
osteoconductive properties of the sandblasted surfaces.
6
The nature and texture of the surface of the dental im-
plant largely control the response of the tissues to the im-
plant.
7
Textured implant surfaces exhibit more surface
area compared to the smooth surfaces for integration
with bone, they also allow the ingrowth of the tissues.
7
Sandblasting with corundum Al
2
O
3
is the preferred
method for the modification of the surface of dental im-
plants.
1
Particles of different sizes provide regular rough-
ness values, which cause the osteoblasts to change and
bind to the bone.
1
When using Al
2
O
3
, the potential risk of
the presence of remnants of particles with the dissolution
of Al ions into the host tissue cannot be excluded.
5,8–11
It
has also been reported that Al
2
O
3
stimulates the flow of
calcium from the bone.
1,8–10
Aluminum can also compete
with calcium in the healing implant bed.
8
It has also been
shown that aluminum can accumulate at the mineraliza-
tion front and in the osteoid matrix.
5,8
Aluminum ions
can also inhibit the normal differentiation of the bone
marrow stromal cells and normal bone deposition and
mineralization.
5
The presence of alloying elements in ti-
tanium alloys, such as Al, probably influences the ad-
sorption of proteins on the surface and therefore modi-
fies the surface-cell interaction.
9–11
5 CONCLUSIONS
Retained Al
2
O
3
contamination on the surface of Ti or
a Ti alloy affects the osseointegration and longevity of
the implant. On the surface of the new implants no Al
2
O
3
contamination was detected, which indicated the use of
another surface-roughening method. Our results on tita-
nium dental implants are similar to the results of the
study with explanted metallic endoprostheses. TiO
2
blasting had positive effects on the osseointegration and
S. @ARKOVI] GJURIN et al.: CHARACTERIZATION OF NEW AND RETRIEVED TITANIUM BIOMATERIAL ...
36 Materiali in tehnologije / Materials and technology 55 (2021) 1, 33–37
Figure 6: SE image of a cross-section of a new dental implant sample
2, a) detail of implant, b) surface at higher magnification with no co-
rundum contamination, c) joint of cpTi part (red and Ti6Al4V (blue)
and d) sum EDS spectrum of cpTi and Ti6Al4V part from selected ar-
eas; EDS shows two different material cpTi (red square) and
Ti6Al4V(blue square), e) and f) cross-section of surface at higher
magnification with no Al
2
O
3
residue.

on the biomechanical features of the implants; therefore,
TiO
2
blasting can be recommended instead of Al
2
O
3
blasting.
Acknowledgment
This research was funded by the Slovenian Research
Agency ARRS (P2-0132–Research Program Institute of
Metals and Technology).
Conflict of interest
The authors declare they have no conflict of interest.
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