Banca de DEFESA: TEREZA JANUARIA COSTA DIAS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : TEREZA JANUARIA COSTA DIAS
DATE: 31/05/2021
TIME: 14:30
LOCAL: Por meio de videoconferência
TITLE:
KEY WORDS:

nanoparticles, nanocrystals, thermometers, resin cement.

PAGES: 77
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUMMARY:

Nanothermometry is the science that quantifies temperatures with the help of materials
that are presented in nanometric scales. This technique has high accuracy and makes
it possible to evaluate temperature changes with an interval of 0.5 oC. It can be applied
both in the biological area and in materials science. This thesis aimed to validate the
use of rare earth nanoparticles to measure temperature, through nanothermometry, in
photoactivated resin cement. Rare earth nanoparticles were synthesized, and the
fluorescence was explored as a nanothermometric sensor. The first set of experiments
had nanoparticles of β-NaYbF4: 1% Tm3 + @ β-NaLuF4: 30% Nd3 + used and
manipulated with the resin cement. The diode LASER was used as source of
excitation. The second set of experiments, Y2O3: Eu3 + nanoparticles were used,
synthesized by combustion method and excited with LED. In order to carry out the
experiments, in both studies, bovine teeth were used as a reference for cementation
of ceramic veneers based on lithium disilicate and with a thickness of 0.5 mm with a
high translucency insert in color A1. The nanoparticles were placed on a thermal plate,
which increased the temperature in a range of 25 to 50 oC. The temperature was
monitored and the emission of fluorescence was captured by each assembled system.
Then, each group of nanoparticles was mixed with the resin cement. Emission
assessments were made only on cement with nanoparticles and, separately, on
cement with nanoparticles with interposition of the ceramic veneer, performing
cementation. Then, photoactivated with blue LED and captured the fluorescence signal
with excitation through LASER and LED corresponding to each group. With first
experiment nanoparticles, the fluorescence emission occurred in a range of 850 to
1000 nm, at temperatures of 20 to 80 oC. There was a difference in temperature with
and without interposition of the ceramic laminate regarding the exothermic reaction of
cement curing. It was also possible to carry out quality control in the distribution of resin
cement under restoration by capturing the fluorescence emission with veneer’s
interposition. For the second study, the fluorescence emission was in a range of 550
to 610 nm. In this experiment, excitation was performed with the aid of blue and green
LED, 480 and 532nm, respectively. High accuracy of the sensor was also observed,
with emissions in a range of 550 to 610nm, when excited from 25 to 50 oC. The same
result was obtained from the previous experiment regarding the capture of fluorescence with the interposition of the ceramic veneer for resina cement light curing (about 12 oC in the reduction of temperature). Thus, the data obtained indicate a  decrease in fluorescence emission as the temperature increases. Thus, it was concluded that nanothermometry has excellent applicability, since it does not need to destroy the sample, it has high efficiency and low cost.

BANKING MEMBERS:
Presidente - 2455989 - LUIZ ALCINO MONTEIRO GUEIROS
Interno - 2284980 - GUSTAVO PINA GODOY
Interna - 3496161 - JULIANA RAPOSO SOUTO MAIOR COSTA
Externo ao Programa - 1760478 - EMERY CLEITON CABRAL CORREIA LINS
Externo à Instituição - HELINANDO PEQUENO DE OLIVEIRA