1. HEAT TRANSMISSION ON DENTIN IRRADIATED BY
Er,Cr:YSGG LASER FOR CARIES PREVENTION
Valter Valentim Lula Júnior1, Profa. Dra. Denise Maria Zezell2, Profa. Dra. Patrícia Aparecida da Ana1
1Universidade Federal do ABC (UFABC) - Av. dos Estados, 5001, Santo André, SP
2Instituto de Pesquisas Energéticas e Nucleares (IPEN) - Av. Lineu Prestes 2242, Cidade Universitária, São Paulo, SP
valter.junior@ufabc.edu.br, zezell@usp.br, patricia.ana@ufabc.edu.br
Advanced School On Modern Trends Of Biophotonics For Diagnosis And Treatment Of Cancer And Microbial Control, April 11 to 19, 2013
Abstract. The temperature changes on root dentin surface and pulp chamber of uniradicular
teeth were analysed during Er,Cr:YSGG laser irradiation at low fluences, aiming to determine
a promissory parameter for future clinical application for caries prevention in dentin.
Keywords: Er,Cr:YSGG laser, temperature, caries prevention.
INTRODUCTION
Dentin exposure by gingival recession makes teeth more sensible to pain and more
susceptible to caries lesions (Fig. 1).
MATERIAL AND METHODS
Fig. 1 A) Healthy gingiva showing knife-edge border of the free gingiva that is scalloped
in shape; B) Gingival recession, with dental root exposure due to gingival margin
migration apical to the cemento-enamel junction (SCHEID and WEISS, 2012).
RESULTS
CONCLUSION
According to the obtained results, the fluence of 2.8 J/cm² can be a promissory parameter
for caries prevention on root dentin.
ACKNOWLEDGMENTS
To IPEN for the laboratorial and CEPOF for the accomodation support.
REFERENCES
ANA, P. A. Estudo in vitro da resistência à desmineralização e da retenção de flúor em esmalte dental irradiado
com laser de Er,Cr:YSGG. 2007. Tese (Doutorado) Instituto de Pesquisas Energéticas e Nucleares, São Paulo.
SCHEID, R. C.; WEISS, G. Woelfel's Dental Anatomy. 8. ed. Philadelphia: LWW, 2012.
ZACH, L.; COHEN, G. Pulp response to externally applied heat. Oral Surg., v. 19, n. 4, p. 515-30, 1965
Gingival recession
Root and dentinal
tubules exposure
Severe root caries
and hypersensitivity
Hi-power
laser heating
(Fig. 2)
Chemical changes
in dentin (Fig. 3)
Risk of pulpal
damage
Dentin surface and
pulpar chamber
heating analysis
Safe and effective
parameters for
caries prevention
X
Fig. 2 Absorbance spectrum of the main
componentes of biological tissues, related to
the main laser wavelenghts used in dentistry.
(ANA, 2007).
Fig. 3 Chemical changes in dental hard
tissues after laser heating. According to the
temperature, it is possible to note changes
in water, carbonate and organical material
content, as well as the transformation of
phosphate in pirophosphate, increase of
hydroxyl and formation of new
crystallographic phases, which leads to
decrease of acid solubility (ANA, 2007).
20 incisor human teeth
Pulp removal
Opening of teeth
lingual surfaces
Placing of thermocouple (Fig. 4)
10 teeth in
group A
10 teeth in
group B
Group A:
2,8 J/cm2
Group B:
5,6 J/cm2
Er,Cr:YSGG pulsed
laser irradiation for
20s
Thermocouple and thermographic
camera heat analysis (Fig. 5)
Statistical analysis (Table 1)
Fig. 4 Thermocouple placing.
Fig. 5 Root dentin irradiation.
Fig. 5 Infrared images during radicular dentin irradiation; a) at beginning, b) during
irradiation; c) imediatelly after irradiation; d) during tooth cooling.
Fig. 6 Surface temperature changes
during Er,Cr:YSGG laser irradiation at
2.8 J/cm2.
Fig. 7 Pulpal temperature changes
during laser irradiation detected with
thermocouple
Dentin surface temperature data evidences
Er,Cr:YSGG laser potential on trigger chemical
changes in dentin when irradiated with 5.6
J/cm² fluence, due to temperature raises
above 100°C. Nevertheless, even with less
chemical changes due to lower temperature
raises, 2.8 J/cm² fluence suggests to be more
indicated because it was not induced
intrapulpal temperature raises higher than
5.5°C, without pulpal damage risk (ZACH and
COHEN, 1965).
Laser
Thermocouple
Thermographic
camera
Tooth
Dental wax
0 20 40 60 80 100
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
T(
o
C)
Time (s)
2.8 J/cm
2
5.6 J/cm
2
0 20 40 60 80
20
30
40
50
60
70
Temperature(
o
C)
Time (s)
2.8 J/cm
2