Abstract
This study aimed to evaluate the effects of repeated CO2 laser applications on the inhibition of enamel demineralization. Sixty-five human dental enamel slabs were randomly assigned to the following groups (n = 13): control (C), one application of the CO2 laser (L1), two applications of the CO2 laser (L2), three applications of the CO2 laser (L3), and four applications of the CO2 laser (L4). Enamel slabs were irradiated by a 10.6-μm CO2 laser operating at 5 J/cm2. The slabs were subjected to a pH-cycling regimen and then analyzed by FT-Raman spectroscopy, energy-dispersive X-ray fluorescence spectrometry (EDXRF), cross-sectional micro-hardness, and scanning electron microscopy (SEM). Statistical analysis was performed using ANOVA and Tukey tests (p < 0.05). FT-Raman spectroscopy showed a reduced carbonate content for L1, L3, and L4 groups when compared to C (p < 0.05). The EDXRF data showed no statistical differences between the control and irradiated groups for calcium and phosphorus components (p > 0.05). Cross-sectional micro-hardness data showed a statistically significant difference between the control and all irradiated groups (p < 0.05), but no difference was found among the irradiated groups (p > 0.05) up to 30-μm depth. A tendency of lower demineralization occurred in deeper depths for L3 and L4 groups. The SEM results showed that with repeated applications of the CO2 laser, a progressive melting and recrystallization of the enamel surface occurred. Repeated irradiations of dental enamel may enhance the inhibition of enamel demineralization.
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References
Micheelis W, Bauch J (1996) Oral health of representative samples of Germans examined in 1989 and 1992. Community Dent Oral Epidemiol 24:62–70. doi:10.1111/j.1600-0528.1996.tb00815.x
Maiman TH (1960) Stimulated optical radiation in ruby. Nature 187(4736):493–494. doi:10.1038/187493a0
Stern RH, Vahl J, Sonnaes RF (1972) Lased enamel: ultrastructural observations of pulsed carbon dioxide laser effects. J Dent Res 51:455–460. doi:10.1177/00220345720510023501
Nelson DGA, Shariati M, Glena R, Shields CP, Featherstone JDB (1986) Effect of pulsed low energy infrared laser irradiation on artificial caries-like lesion formation. Caries Res 20:289–299. doi:10.1159/000260948
Patel CKN, McFarlane RA, Faust WL (1964) Selective excitation through vibrational energy transfer and optical laser action in N2-CO2. Physiol Rev 13:617–619
Nelson DGA, Jongedloed WL, Featherstone JBD (1986) Laser irradiation of human dental enamel. N Z Dent J 82:74–77
Moshonov J, Stabholz A, Bar-Hilel R, Peretz B (2005) Chemical analysis and surface morphology of enamel and dentin following 9.6 μm CO2 laser irradiation versus high speed drilling. J Dent 33:427–432. doi:10.1016/j.jdent.2004.11.005
Rodrigues LKA, Nobre-dos-Santos M, Pereira D, Assaf AV, Pardi V (2004) Carbon dioxide laser in dental caries prevention. J Dent 32:531–540. doi:10.1016/j.jdent.2004.04.004
Klein AL, Rodrigues LK, Eduardo CP, Nobre-dos-Santos M, Cury JA (2005) Caries inhibition around composite restorations by pulsed carbon dioxide laser application. Eur J Oral Sci 113:239–244. doi:10.1111/j.1600-0722.2005.00212.x
Steiner-Oliveira C, Rodrigues LK, Soares LE, Martin AA, Zezell DM, Nobre-dos-Santos M (2006) Chemical, morphological and thermal effects of 10.6-μm CO2 laser on the inhibition of enamel demineralization. Dent Mater J 25(3):455–462. doi:10.4012/dmj.25.455
Hess JA (1990) Scanning electron microscopy study of laser-induced morphologic changes of a coated enamel surface. Lasers Surg Med 10:458–462. doi:10.1002/lsm.1900100510
Arcoria CJ, Lippas MG, Vitasek BA (1993) Enamel surface roughness analysis after laser ablation and acid etching. J Oral Rehabil 20:213–224. doi:10.1111/j.1365-2842.1993.tb01603.x
Aminzadeh A, Shahabi S, Walsh LJ (1999) Raman spectroscopic studies of CO2 laser-irradiated human dental enamel. Spectrochim Acta A Mol Biomol Spectrosc 55:1303–1308. doi:10.1016/S1386-1425(99)00035-9
Takahashi K, Kimura Y, Matsumoto K (1998) Morphological and atomic analytical changes after CO2 laser irradiation emitted at 9.3 microns human dental hard tissue. J Clin Laser Med Surg 16:167–173
de Souza-e-Silva CM, Parisotto TM, Steiner-Oliveira C, Kamiya RU, Rodrigues LK, Nobre-dos-Santos M (2013) Carbon dioxide laser and bonding materials reduce enamel demineralization around orthodontic brackets. Lasers Med Sci 28:111–118. doi:10.1007/s10103-012-1076-5
Esteves-Oliveira M, Zezell DM, Meister J, Franzen R, Stanzel S, Lampert F, Eduardo CP, Apel C (2009) CO2 laser (10.6 μm) parameters for caries prevention in dental enamel. Caries Res 43:261–268. doi:10.1159/000217858
Hsu CYS, Jordan TH, Dederich DN, Wefel JS (2000) Effects of low-energy CO2 laser irradiation on the organic matrix inhibition of enamel demineralization. J Dent Res 79:1725–1730. doi:10.1177/00220345000790091401
Hossain M, Nakamura Y, Kimura Y, Mitsuhiro I, Yamada Y, Matsumoto K (1999) Acquired acid resistance of dental hard tissues by CO2 laser irradiation. J Clin Laser Med Surg 17:223–226. doi:10.1089/clm.1999.17.223
Featherstone JD, Barrett-Vespone NA, Fried D, Kantorowitz Z, Seka W (1998) CO2 laser inhibitor of artificial caries-like progression in dental enamel. J Dent Res 77:1397–1403. doi:10.1177/00220345980770060401
Rodrigues LK, Nobre Dos Santos M, Featherstone JD (2006) In situ mineral loss inhibition by CO2 laser and fluoride. J Dent Res 85:617–621. doi:10.1177/154405910608500707
Featherstone JDB, Fried D, Gansky SA, Stookey GK, Dunipace A (2001) Effect of carbon dioxide laser treatment on lesion progression in an intra-oral model. Lasers Dent SPIE VII 4249:87–91
Palamara J, Phakey PP, Rachinger WA (1987) The ultrastructure of human dental enamel heat-treated in the temperature range 200 °C to 600 °C. J Dent Res 66:1742–1747
Ferreira JM, Palamara J, Phakey PP, Rachinger WA, Orams HJ (1989) Effects of continuous wave CO2 laser on the ultrastructure of human dental enamel. Arch Oral Biol 34:551–62
Zuerlein MJ, Fried D, Featherstone JDB (1999) Modeling the modification depth of carbon dioxide laser-treated dental enamel. Lasers Surg Med 25:335–347. doi:10.1002/(SICI)1096-9101
Tagliaferro EPS, Rodrigues LKA, Soares LES, Martin AA, Nobre-dos-Santos (2009) Physical and compositional changes on demineralized primary enamel induced by CO2 laser. Photomed Laser Surg 27:585–590. doi:10.1089/pho.2008.2311
Rodrigues LK, Cury JA, Nobre-dos-Santos MN (2004) The effect of gamma radiation on enamel hardness and its resistance to demineralization in vitro. J Oral Sci 46:215–220. doi:10.2334/josnusd.46.215
Featherstone JDB, Shariati M, Brugler S, Fu J, White DJ (1988) Effect of an anticalculus dentifrice on lesion progression under pH-cycling conditions in vitro. Caries Res 22:337–341. doi:10.1159/ 000261133
Steiner-Oliveira C, Rodrigues LKA, Lima EB, Nobre-dos-Santos MN (2008) Effect of the CO2 laser combined with fluoridated products on the inhibition of enamel demineralization. J Contemp Dent Pract 9:1–10
Fattibene P, Carosi A, De Coste V, Sacchetti A, Nucara A, Postorino P et al (2005) A comparative EPR, infrared and Raman study of natural and deproteinated tooth enamel and dentin. Phys Med Biol 50:1095–1108. doi:10.1088/0031-9155/50/6/004
Nishino M, Yamashita S, Aoba T, Okazaki M, Moriwaki Y (1981) The laser-Raman spectroscopic studies on human enamel and precipitated carbonate-containing apatites. J Dent Res 60:751–755. doi:10.1177/00220345810600031601
Rehman I, Smith R, Hench LL, Bonfield W (1995) Structural evaluation of human and sheep bone and comparison with synthetic hydroxyapatite by FT-Raman spectroscopy. J Biomed Mater Res 29:1287–1294. doi:10.1002/jbm.820291016
Rehman I, Hench LL, Bonfield W, Smith R (1994) Analysis of surface layers on bioactive glasses. Biomaterials 15:865–870. doi:10.1016/0142-9612(94)90044-2
Nelson DG, Williamson BE (1985) Raman spectra of phosphate and monofluorophosphate ions in several dentally-relevant materials. Caries Res 19:113–121. doi:10.1159/000260837
Fowler BO, Kuroda S (1986) Changes in heated and laser-irradiated human tooth enamel and their probable effects on solubility. Calcif Tissue Int 38:197–208. doi:10.1007/BF02556711
McCormack SM, Fried D, Featherstone JDB, Glena RE, Seka W (1995) Scanning electron microscope observations of CO2 laser effects on dental enamel. J Dent Res 74:1702–1708. doi:10.1177/00220345950740101201
Hirose M, Tange T, Igarashi S, Hirose Y, Nakagaki H (1996) In vivo fluoride profiles at different sites of buccal and lingual enamel surfaces obtained by enamel biopsy of human maxillary first permanent molars in young adults. Arch Oral Biol 41:1187–1190. doi:10.1016/S0003-9969(96)00089-1
Acknowledgments
This paper was based on a thesis submitted by the first author, which received a scholarship from CAPES, to Piracicaba Dental School, University of Campinas, in partial fulfillment of the requirements for a Ph.D. degree in Dentistry (Pediatric Dentistry area).
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Vieira, K.A., Steiner-Oliveira, C., Soares, L.E.S. et al. In vitro evaluation of enamel demineralization after several overlapping CO2 laser applications. Lasers Med Sci 30, 901–907 (2015). https://doi.org/10.1007/s10103-013-1493-0
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DOI: https://doi.org/10.1007/s10103-013-1493-0
Keywords
- CO2 laser
- Dental enamel
- Demineralization
- SEM
- FT-Raman