Objective: The aim of this study was to assess any long-term chemical and morphological Nd:YAG laser modifications on irradiated primary enamel. Background data: Previous studies on irradiated primary human enamel employed methodologies that evaluated the short-term effects only. Methods: One hundred and eighty-six irradiated (with and/or without fluoride) primary enamel teeth from high-caries-risk children, which were exfoliated over a 1-year period, were collected, and the sample surface area was submitted for scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray energy-dispersive spectrometry (EDS). The subsurface was analyzed by Knoop microhardness and light microscopy (LM). Data were analyzed by one way ANOVA and Tukey tests (α=0.05) and Kruskall–Wallis and Tukey tests (α=0.05). Results: FTIR analysis revealed a higher concentration of phosphate and carbonate in the irradiated (0.987±0.064) and lower concentration in the control groups (1.477±0.310). SEM analysis showed that the control samples exhibited a slightly smoother surface than the irradiated groups. The EDS analysis did not show any differences in the amount of calcium, phosphorus, or fluoride among the groups. The microhardness analysis revealed that sealant (249.86±7.15) and laser irradiation (262.44±22.69) led to higher hardness values than the negative control group (128.35±25.19). LM indicated significantly reduced caries formation in the laser (5.35±5.38%) and the laser plus acidulated phosphate fluoride (APF) groups (10.35±0.88%) compared with the negative control group (72.56±12.86%). Conclusions: Even with the limitations of the present study, these results suggest that Nd:YAG irradiation clinically modified the chemical composition of the enamel surface regardless of fluoride concentration, which successfully inhibited demineralization of primary tooth enamel over a 1-year period without significant morphological changes.
OhoT, MoriokaT. A possible mechanism of acquired acid resistance of human dental enamel by laser irradiation. Caries Res, 1990; 24:86–92.
3.
TagomoriS, IwaseT. Ultrastructural change of enamel exposed to a normal pulsed Nd-YAG laser. Caries Res, 1995; 29:513–520.
4.
PelinoJE, MelloJB, EduardoCP, JorgeAO. In vitro study of the Nd:YAG laser effect on human dental enamel: optical and scanning electron microscope analysis. J Clin Laser Med Surg, 1999; 17:171–177.
5.
ChenCC, HuangST. The effects of lasers and fluoride on the acid resistance of decalcified human enamel. Photomed Laser Surg, 2009; 27:447–452.
6.
ApelC, MeisterJ, GötzH, DuschnerH, GutknechtN. Structural changes in human dental enamel after subablative erbium laser irradiation and its potential use for caries prevention. Caries Res, 2005; 39:65–70.
7.
BediniR, ManzonL, FrattoG, PecciR. Microhardness and morphological changes induced by Nd:YAG laser on dental enamel: an in vitro study. Ann Ist Super Sanita, 2010; 46:168–172.
8.
GraaffR, DasselACM, KoelinkMH, MulFFM, AarnoudseJG, ZijlstraWG. Optical properties on human dermis in vitro and in vivo. Appl Opt, 1993; 32:435–447.
9.
GutknechtN. Proceedings of the 1st International Workshop of Evidence Based Dentistry on Lasers in Dentistry. London, Berlin, Chicago: Quintessenz Publishing Co. Ltd., 2007.
10.
JennettE, MotamediM, RastegarS, FredericksonC, ArcoriaC, PowersJM. Dye-enhanced ablation of enamel by pulsed lasers. J Dent Res, 1994; 73:1841–1847.
11.
HuangGF, LanWH, GuoMK, ChiangCP. Synergistic effect of Nd:YAG laser combined with fluoride varnish on inhibition of caries formation in dental pits and fissures in vitro. J Formos Med Assoc, 2001; 100:181–185.
12.
GelskeySC, WhiteJM, GelskeyDE, KremersW. Vapor emissions resulting from Nd:YAG laser interaction with tooth structure. Dent Mater, 1998; 14:453–457.
13.
AzevedoDT, Faraoni-RomanoJJ, Derceli JdosR, Palma-DibbRG. Effect of Nd:YAG laser combined with fluoride on the prevention of primary tooth enamel demineralization. Braz Dent J, 2012; 23:104–109.
14.
Raucci-NetoW, de Castro-RaucciLM, LepriCP, Faraoni-RomanoJJ, da SilvaJM, Palma-DibbRG. Nd:YAG laser in occlusal caries prevention of primary teeth: a randomized clinical trial. Lasers Med Sci, 2015; 30:761–768.
15.
GoodmanBD, KaufmanHW. Effects of an argon laser on the crystalline properties and rate of dissolution in acid of tooth enamel in the presence of sodium fluoride. J Dent Res, 1977; 56:1201–1207.
16.
BaharA, TagomoriS. The effect of normal pulsed Nd-YAG laser irradiation on pits and fissures in human teeth. Caries Res, 1994; 28:460–467.
17.
ØgaardB, RøllaG, RubenJ, ArendsJ. Relative cariostatic effects of KOH-soluble and KOH- insoluble fluoride in situ. J Dent Res, 1990; 69:1505–1507.
18.
ØgaardB, SeppäL, RøllaG. Professional topical fluoride applications-–clinical efficacy and mechanism of action. Adv Dent Res, 1994; 8:190–201.
19.
RøllaG, SaxegaardE. Critical evaluation of the composition and use of topical fluorides, with emphasis on the role of calcium fluoride in caries inhibition. J Dent Res, 1990; 69:820–823.
20.
ØgaardB, RöllaG, HelgelandK. Uptake and retention of alkali-soluble and alkali-insoluble fluoride in sound enamel in vivo after mouthrinses with 0.05% or 0.2% NaF. Caries Res, 1983; 17:520–524.
21.
DijkmanAG, de BoerP, ArendsJ. In vivo investigation on the fluoride content in and on human enamel after topical applications. Caries Res, 1983; 17:392–402.
22.
DijkmanTG, ArendsJ. The role of ‘CaF2-like’ material in topical fluoridation of enamel in situ. Acta Odontol Scand, 1988; 46:391–397.
23.
NammourS, DemortierG, FlorioP, et al.Increase of enamel fluoride retention by low fluence argon laser in vivo. Lasers Surg Med, 2003; 36:260–263.
24.
DummerPM, KingdonA, KingdonR. Prevalence and distribution by tooth type and surface of developmental defects of dental enamel in a group of 15- to16-year-old children in South Wales. Community Dent Health, 1990; 7:369–377.
25.
TepperSA, ZehnderM, PajarolaGF, SchmidlinPR. Increased fluoride uptake and acid resistance by CO2 laser-irradiation through topically applied fluoride on human enamel in vitro. J Dent, 2004; 32:635–641.
26.
Correa-AfonsoAM, Ciconne-NogueiraJC, PécoraJD, Palma-DibbRG. In vitro assessment of laser efficiency for caries prevention in pits and fissures. Microsc Res Tech, 2012; 75:245–252.
27.
ZezellDM, BoariHG, AnaPA, EduardoCP, PowellGL. Nd:YAG laser in caries prevention: a clinical trial. Lasers Surg Med, 2009; 41:31–35.
28.
FeatherstoneJD, Barrett-VesponeNA, FriedD, KantorowitzZ, SekaW. CO2 laser inhibitor of artificial caries-like lesion progression in dental enamel. J Dent Res, 1998; 77:1397–1403.
29.
González-RodríguezA, de Dios López-GonzálezJ, del CastilloJD, Villalba-MorenoJ. Comparison of effects of diode laser and CO2 laser on human teeth and their usefulness in topical fluoridation. Lasers Med Sci, 2011; 26:317–324.
30.
MajoriM, ManzonL, PaneS, BediniR. Effects of Nd:YAG laser on dental enamel. J. Appl Biomater Biomech, 2005; 3:128–133.
31.
BandaNR, Vanaja ReddyG, ShashikiranND. Evaluation of primary tooth enamel surface morphology and microhardness after Nd:YAG laser irradiation and APF gel treatment – an in vitro study. J Clin Pediatr Dent, 2011; 35:377–382.
TavaresJG, EduardoCP, BurnettLH, BoffT, de FreitasPM. Argon and Nd:YAG lasers for caries prevention in enamel. Photomed Laser Surg, 2012; 30:433–437.
34.
Antunes, de RossiW, ZezellDM. Spectroscopic alterations on enamel and dentin after nanosecond Nd:YAG laser irradiation. Spectrochim Acta A Mol Biomol Spectrosc, 2006; 64:1142–1146.
35.
RobinsonC, ShoreRC, BrookesSJ, StraffordS, WoodSR, KirkhamJ. The chemistry of enamel caries. Crit Rev Oral Biol Med, 2000; 11:481–495.
36.
ShellisRP, WahabFK, HeywoodBR. The hydroxyapatite ion activity product in acid solutions equilibrated with human enamel at 37C. Caries Res, 1993; 27:365–372.
37.
Correa-AfonsoAM, BachmannL, AlmeidaCG, CoronaSA, BorsattoMC. FTIR and SEM analysis of CO2 laser irradiated human enamel. Arch Oral Biol, 2012; 57:1153–1158.
