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

at each energy level. The degree of conversion results at
90 s and Knoop microhardness results made after 5 min
and 18 h were analyzed with ANOVA and Fisher’s PLSD at
˛ = 0.01.
Results: The energy delivered by the attendees to the
same tooth ranged from 2.0 to 20.9 J/cm 2 . There was no
significant improvement in the DC or Knoop hardness of
Tetric EvoCeram A2 between 12 and 35.4 J/cm 2 confirming
the manufacturer’s curing instructions. 43% of light curings
obtained at the AADR meeting would result in Tetric EvoCeram
not receiving the manufacture’s recommended minimum
amount of energy. This will adversely affect the degree of
conversion and the Knoop microhardness. 82% of the simulated
light curings would deliver less than the 16 J/cm 2
recommended in the Phillip’s Science of Dental Materials
textbook.
Conclusions: This and other studies using MARC strongly
suggest that the curing energies delivered to resins in many
dental offices are inadequate and will result in undercured
resins, despite the fact that the dentists may think they are
following the manufacturer’s guidelines. BlueLight Analytics
supported this study.
doi:10.1016/j.dental.2010.08.085
78
Effect of modulated photoactivation methods on mechanical
properties of composites with different loading systems
E.J. Souza-Junior 1 , R.C.B. Alonso 2 , Lams Paulillo 1 ,C.
Anauate-Neto 2 , R.M. Puppin-Rontani 1
1 State University of Campinas, Brazil
2 Bandeirante University of São Paulo, Brazil
Objectives: To investigate the influence of modulated
photoactivation methods on degree of conversion, Knoop
hardness, crosslink density, elastic modulus, and flexural
strength of composites with different loading systems (microfilled,
nanofilled and hybrid).
Material and methods: Different composites were selected
based on the loading system (Microfilled: Durafill; Nanofilled:
Z350; Hybrid: Z250). Bar specimens (5 mm length × 2mm
width × 1 mm height) were confectioned in a polyvinylsiloxane
mold and photocured using 3 methods: Continuous
light (CL); Soft-Start (SS); and Pulse-delay (PD). For all
methods the energy dose was 16 J. All properties were
evaluated on the same specimens (n = 10). Degree of conversion
(DC) was determined by means of FTIR. Knoop
hardness (KHN) was conducted using microhardness tester
(50 g for 5 s). Crosslink density (CLD) evaluation was performed
by hardness measures before and after storage in
absolute-ethanol for 24 h. The % of hardness reduction was
considered. To determine flexural strength (FS) and elastic
modulus (E), a three-point flexural test was conducted
in a Universal testing machine (3 mm between the supports)
with a cross-head speed of 0.5 mm/min. Data of each
test were submitted to two way ANOVA and Tukey’s test
(p > 0.05).
dental materials 26S (2010) e1–e84 e37
Results: Results are showed in the tables as follows:
DC (%) CL SS PD KHN CL SS PD
Micro 69.4 aB 70.9 aB 80.4 aA Micro 13.3 cA 14.9 cA 14.9 cA
Nano 54.6 bA 53.9 bA 47.6 cB Nano 57.1 bA 59.4 bA 57.7 bA
Hybrid 54.1 bA 52.1 bA 52.6 bA Hybrid 71.8 aA 66.6 aB 64.2 aB
CLD (%) CL SS PD E (GPa) CL SS PD
Micro 09.7 bB 29.5 aA 26.7 cA Micro 1.16 bA 1.31 bA 1.04 bA
Nano 29.2 aB 28.8 aB 38.4 bA Nano 3.63 aA 4.05 aA 3.35 aA
Hybrid 35.1 aB 36.2 aB 44.9 aA Hybrid 3.26 aA 3.37 aA 3.47 aA
FS (MPa) CL SS PD
Micro 48.3 cA 32.0 cA 42.0 bA
Nano 93.8 bAB 76.5 bB 99.3 aA
Hybrid 141.7 aA 104.7 aB 104.3 aB
For all tables, mean values followed by different small
letters in the column and capital letters in the row differ statistically
among themselves for the Tukey test at the level of
5%.
Conclusions: Filler loading affected all the tested properties.
In general, microfilled composite showed inferior
mechanical properties, while hybrid and nanocomposites
shows better properties. Modulated photoactivation methods
affected in different ways the DC, reduced KHN, CLD and FS,
but not affected E.
doi:10.1016/j.dental.2010.08.086
79
Withdrawn
doi:10.1016/j.dental.2010.08.087
80
Evaluation of depth of cure in nanohybrid composite: Scraping
vs. Micro F-TIR analysis
R. Rota 1 , N. Scotti 1 , A. Venturello 2 , D. Pasqualini 1 , E. Berutti 1
1 University of Turin, Italy
2 Polytechnical School of Turin, Italy
Objectives: The aim of this in vitro study was to compare
two different methods for evaluating depth of cure of resin
composites.
Materials and methods: A commercially available nanohybrid
resin composite (Venus Diamond, Heraeus Kultzer,
Hanau, Germany) was selected for this study. The resin composite
was bulk placed inside a metal mold, which allowed
the depth of cure examination. Semicircular samples (10 mm
depth) were obtained, with a later flat surface parallel to the
curing light direction. A total of 48 samples were prepared with
different curing parameters: energy density (400 mW/cm 2 ;
2000 mW/cm 2 ) and curing time (10 s; 40 s). The curing device
employed in this study was a halogen light (Swiss Master
Light, EMS, Switzerland). The degree of conversion (DC) was
accomplished by Micro Attenuated Total Reflection Fourier
Transform Infrared (ATR F-TIR) analysis 24 h after the polymerization.
DC was recorded every 0.25 mm along the lateral
surface of the sample. Sufficient depth of cure was considered
at the level where DC was 80% of the maximum DC of
each sample. After Micro F-TIR examinations, the composite
was carefully removed from the mold and uncured material
gently removed using a plastic spatula. The height of the
cylinder of cured material was measured with a microme-