Análise das propriedades mecânicas, grau de conversão e profundidade de polimerização de resinas compostas polimerizadas com diferentes unidades fotoativadoras de LED
Nenhuma Miniatura disponível
Data
2021-02-24
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
This study analyzed the irradiance and spectrum by emission spectrophotometry (MARC-RC),
characterized the light beams (Beam Profile), as well as determined the Knoop microhardness
(KHN), the modulus of elasticity (GPa), the degree of conversion ( %), the flexural strength of
3 points (MPa) and the polymerization depth with elasticity modulus of a composite (Filtek
Z350 XT) photopolymerized with 5 different types of LED curing units. Of these, three types
were not certified by ANVISA and Inmetro, Dental Wireless (E1), Li A180 (E2) and Lyang Ya
(E3), and two with certification, VALO Cordless - Ultradent (VL) and Elipar Deep-Cure L - 3
Oral Care (EL). The characterization was carried out by determining irradiance (mW / cm²),
emission spectrum (mW / cm² / nm) and radiant exposure (J / cm²) using the MARC Resin
Calibrator (MARC-RC, BlueLight). The Beam Profile of the different photoactivating units was
made by means of a laser beam profile reader (Beam Profile). 50 specimens were produced
for testing microhardness and modulus of elasticity. Each experimental group was
polymerized with a photoactivator unit. Microhardness (KHN) was obtained by averaging five
indentations on each surface. The modulus of elasticity was obtained by measuring the major
and minor diagonals of each indentation. The degree of conversion was obtained by the FTIR /
ATR test with 25 specimens. The 3-point flexural strength test (n = 50) was performed using
a load in the center of the sample with a constant speed of 0.5 mm / min until fracture. The
maximum load was recorded in Newtons. The depth of polymerization of the restoration was
evaluated by Knoop microhardness using the average indentations in the regions: mesial,
center and distal of healthy human molars prepared in Class II and restored using an oblique
incremental technique. The modulus of elasticity of the polymerization depth of the
restoration was obtained in the same way as the previous microhardness test. The test data
were subjected to the normality test (Shapiro-wilk) followed by Factor analysis of variance
(One-way ANOVA), Two-factor analysis of variance (Two-way ANOVA), Tukey HSD test (α =
0, 05) and multiple linear regression. In all tests, the groups showed statistically significant
differences between them (p <0.001). The non-certified units (E1, E2 and E3) presented nonhomogeneous
light beam profiles with concentrated irradiance in the center of the active tips.
E3 showed greater irradiance when compared to the other photoactivating units. VL and EL
showed larger diameters between the different photoactivating units. In the microhardness
(KHN) and elastic modulus (GPa) tests, VL presented the highest mean values in both and E1,
the lowest mean values. VL showed higher values of degree of conversion (%) when
compared to EL and E3. The highest values of flexural strength (MPa) were E3 when
compared to the other groups, being statistically similar to the VL and E2 groups. At depths
closer to the pulp wall, lower mean values of microhardness and modulus of elasticity were
obtained. And, the highest mean values of microhardness and modulus of elasticity were
found in the occlusal regions (1mm). The interaction between microhardness and modulus of
elasticity showed a very strong and proportional positive correlation according to the different
depths tested. The analysis of the tests indicated that between microhardness (KHN) and
depth of the restoration, a weak positive correlation was obtained and there was no
association with irradiance (mW / cm²). The modulus of elasticity (GPa) was not related to the
depth of the restoration and to the irradiance (mW / cm²).
Descrição
Palavras-chave
Citação
ALMEIDA, L. M. Análise das propriedades mecânicas, grau de conversão e profundidade de polimerização de resinas compostas polimerizadas com diferentes unidades fotoativadoras de LED. 2021. 70. Tese (Doutorado em Odontologia) - Universidade Federal de Goiás, Goiânia, 2021.