Abstracts of the Academy of Dental Materials Annual ... - IsiRed

tion of colonies of S. mutans and S. total can be able to
determine a significant reduction in the cariogenic risk in
orthodontic patients, especially early in therapy or in case of
loss of compliance.
doi:10.1016/j.dental.2010.08.167
160
Microhardness of MTA and SuperEBA in acid solutions
S. Loghi, D. Nicosia, M. De Biasi, D. Sossi, D. Angerame
University of Trieste, Trieste, Italy
Objectives: Periapical inflammation and pH changes after
endodontic surgery could affect hardening and final characteristics
of retrograde filling materials. The present study
analyzes the microhardness of two retrograde filling materials
stored into different pH solutions.
Materials and methods: 48 discs (24 per material) were prepared
according to manufacturer instructions and randomly
divided in 8 groups (n = 6); they were let harden for 1 (SuperEBA,
Bosworth) or 24 h (MTA, Dentsply) into buffered solutions at
different pH values (pH = 7, pH = 6, pH = 5 and pH = 3). After
storage the upper surface of the specimens was polished using
a 1200 (10 �m) and 2400 (5 �m) sandpaper. Microhardness was
then measured with a Vickers indenter (VHMT 30, Leica). Collected
data were statistically analyzed with Kruskal–Wallis
and Conover tests (p < 0.05).
Results: Mean hardness values (±SD) were:
pH MTA SuperEBA
7 38.59 ± 2.59 18.46 ± 5.38 b
6 3.61 ± 0.76 a 22.81 ± 5.16 c
5 4.02 ± 1.57 a 20.65 ± 5.49 bcd
3 1.21 ± 0.47 21.69 ± 6.10 d
Data expressed in HV.
Same letters indicate no statistical difference.
Conclusions: Within the limits of the present study MTA
showed high sensibility to decreasing pH of the environment,
although at pH 7 it showed the greatest microhardness values.
SuperEBA maintained constant or increased its hardness
with increasing acidity. The pH of the surgical site seems to
be relevant for retrograde filling materials, thus postsurgical
inflammation should be kept under control.
doi:10.1016/j.dental.2010.08.168
161
Mesenchymal stem cells and bovine bone mineral in sinus lift
R. Gutwald 1 , M. Maglione 2 , S. Sauerbier 1 , R. Schmelzeisen 1
1 University of Freiburg, Germany
2 University of Trieste, Italy
Objectives: New reconstructive and less invasive methods
have been searched in order to optimize bone formation and
osseointegration of dental implants in maxillary sinus augmentation.
The aim of the presented ovine split-mouth study
was to compare bovine bone mineral (BBM) alone or in com-
dental materials 26S (2010) e1–e84 e75
bination with mesenchymal stem cells (MSCs) regarding their
potential in sinus augmentation.
Materials and methods: Bilateral sinus floor augmentations
were performed in 6 adult sheep. BBM and MSCs were
placed into the test side and only BBM in the contra-lateral
control side of each sheep. Bone marrow was aspirated from
the iliac crest. MSCs were extracted via Ficoll-separation. A
volume of 3.5 cm 2 of MSCs and BBM were transplanted into the
right sinus (test). The left sinus (control) was augmented only
with BBM. The wounds were closed with resorbable suture
material. All the surgical procedures were carried out by the
same surgeon. The surgical procedures for sinus augmentation
and the follow up were done according to Haas protocol.
Animals were sacrificed after 8 and 16 weeks. Augmentation
sites were analysed by computed tomography, histology, and
histomorphometry.
Results: The initial volumes of both sides were similar and
did not change significantly with time. A tight connection
between the particles of BBM and the new bone was observed
histologically. Bone formation was significantly faster by
49% in the test sides (p = 0.027). The histological sections
showed no signs of inflammation. The newly formed osseous
lamellae appared as a vital bone tissue containing osteocytes
inside the bone lacunae. In comparison to lamellar bone
the biomaterial could be easily identified by its size, shape
and color. The newly formed bone lamellae connected the
biomaterial particles and stabilized the grafted complex. Bone
formation appeared in the macro pores of the biomaterial
as well. Blood vessels could be detected in the biopsy. The
biomaterial with newly formed bone was integrated well in
the surrounding host bone.
Conclusions: The combination of BBM and MSCs accelerated
new bone formation in this model of maxillary sinus
augmentation. This could allow early placement of implants.
doi:10.1016/j.dental.2010.08.169
162
Wetting behaviour of root canal sealers
A. Mokeem Saleh, N. Silikas, D.C. Watts
University of Manchester, UK
Objectives: Wetting behaviour is an important phenomenon
in dentistry in order to achieve good adhesion
between the filling materials and the tooth surface (Combe et
al. Dent Mater. 2004 20:262). In endodontics, root canal sealers
with good flowability and low surface tension can be easily
placed along the entire root canal and be capable of wetting the
canal walls (Stevens et al. J Endod. 2006 32:785). The intimacy
of this contact depends on the wettability of sealers on solid
dentine and this property of the liquid is strictly correlated
to its surface tension (Giardino et al. J Endod. 2006 32:1091).
The purpose of this study was to investigate surface tension of
different endodontic sealers using the pendant drop method.
Materials and methods: Endodontic sealers 1–7 of different
chemical composition were used to measure the surface tension,
all measurements were recorded at 23 ◦ C. Water was
used as a control. Once the profile of the pendant drop
was obtained, a numerical method was used for obtaining