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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 [email protected], [email protected], [email protected]

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/cm2

5.6 J/cm2

0 20 40 60 80

20

30

40

50

60

70

Te

mp

era

ture

(o C

)

Time (s)

2.8 J/cm2