A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel

Abstract

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 microns, energy density 4160 J/cm2) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 microns), energy density 50,000 J/cm2), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.

Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi

“…This thermal mechanism on explosive vaporization of interstitial water has been proposed for Ho:YAG lithotripsy [29]. However, it is well known that clinical long-pulse Ho:YAG laser ablation of calcified tissue occurs without significant thermal damage to surrounding tissue, i.e., thermal confinement occurs [36]. In addition, holmium lithotripsy creates sharply demarcated craters, with microscopic preservation of crystalline lamella on the crater surface, implying a regular, consistent, and stereotypical lasercalculus interaction [9].…”

Subsurface morphologic changes of ND:YAG laser-etched enamel

“…The effects on the morphology of the surface can range from no apparent surface alteration to rather dramatic melting, resolidification, and evaporation of the enamel. In particular, the Nd:YAG laser produces shallow craters with numerous microcavities, micropores, and microfissures as reported by Hess [13] and others [14][15][16][17]22,24]. These studies, however, only reported changes that occurred morphologically at the surface.…”

“…Lasers have been studied for use in the detection [9,25,26] and removal of enamel caries [5,6,28] and cavity preparation [22,29,30,32,34], treating pits and fissures [10,16], in etching the surface for the bonding of dental resin [11,13,20,21,23,24], and in altering the calcium hydroxyapatite crystalline structure to increase caries resistance [7,15]. The types of lasers used in these studies have included: ruby [1,2], carbon dioxide [3][4][5][6][7][8][9][10][11][12]27], Nd:YAG [12][13][14][15][16][17][18][19][20][21][22][23], CO 2 -Nd:YAG [12,23], argon-ion [24]…”

Effect of the Nd:YAG and the Er:YAG Laser on the Adhesive–Dentin Interface: A Scanning Electron Microscopy Study

“…The laser causes surface melting, followed by recrystallization, resulting in small scattered areas and some opened dentinal tubules. 32,33 The recrystallization of the dentinal apatite and formation of additional stages of calcium phosphate increase resistance of hard tissues to acid demineralization, which reduces dentin permeability. 34,35 The 37% phosphoric acid as well as the acid monomer MDP may not have had the same capacity to demineralize the dentin irradiated with the laser in comparison with the groups in which the laser was not applied.…”