Chemical Changes of Enamel Produced by Sodium Fluoride, Hydroxyapatite, Er:YAG Laser, and Combined Treatments

Abstract

Occlusal pits and fissures of permanent molars are considered to have higher risk of developing caries. Enamel demineralization can be prevented by applying remineralizing agents, and their absorption increases with prior irradiation. This work evaluates the chemical changes produced by treating occlusal surfaces with sodium fluoride (NaF), hydroxyapatite-NaF-xylitol (HA-NaF-X), Er:YAG laser irradiation (L), and combinations thereof. Fifty enamel samples were randomly assigned to five groups (n = 10): NaF, HA-NaF-X, L, L + NaF, and L + HA-NaF-X. The chemical composition of human enamel was evaluated before (BT) and after (AT) treatment using energy-dispersive X-ray spectroscopy (EDS) and expressed in atomic percentages (at%). For combined treatment groups, the products were applied after laser irradiation. The statistical analyses included a paired t-test and ANOVA (p ≤ 0 05). After treatment, a significant increase in F at% was observed in the NaF group (2.71 ± 1.41). The irradiated groups showed significant increases in Ca and P at% and the Ca/P ratio. The highest values occurred for L + NaF (30.44 ± 4.28 Ca at%, 11.97 ± 1.45 P at%, and 2.55 ± 0.22 Ca/P ratio). Er:YAG laser irradiation alone or in combined protocols increased the Ca and P content of dental enamel, in vitro.

Acid resistance of dental enamel treated with remineralizing agents, Er:YAG laser and combined treatments

“…14,25 This reduction has been attributed to the surface temperature achieved during enamel laser irradiation, and loss of water and carbonate. 26 In the current study, the selected parameters (low energy density -12.7 J/cm 2 ; pulse energy -100 mJ; frequency -10 Hz; pulse duration -250-400 μs, and water irrigation -5.0 mL/min) were based on previous studies 16,21 and the results of a pilot study.…”

“…Moreover, a previous study reported an increase in the Ca/P ratio under similar conditions for treatments with L+NaF, L+HA-NaF-X, L, and NaF, in decreasing order. 21 However, Comar et al 11 reported that fluoride paste (0.2% NaF) is still the best option for reducing dental demineralization in vitro when compared to HA, CPP-ACP and CPP-ACPF. The use of lasers in combination with CPP-ACPF and HA-NaF-X showed a superior performance, which was a promising result.…”

“…Subsequently, the specimens were cleaned in an ultrasonic bath (Quantrex ® Q140; L&R Ultrasonics, Kearny, USA) with deionized water for 5 min and dried at room temperature. 21 A diagram of the experimental design is shown in Fig. 1.…”

“…The dental surface was scanned manually with the sapphire tip of the laser perpendicular to it, at a working distance of 1 mm and with irrigation (distilled water 5 mL/min). 15,[18][19][20][21] Each sample was irradiated only once for 20 s.…”

The Effect of Combined Treatment by Laser and Fluoride on the Acid Resistance of Enamel in Primary Teeth (In-Vitro Study)

“…On the other hand, Ceballos-Jiménez et al, (38) compared sodium fluoride (NaF) Er: YAG laser irradiation (L), hydroxyapatite-NaF-xylitol, and combinations of laser with each agent and found a significant increase in the elements and the Ca/P ratio between the study groups with the maximum increase in laser + NaF group. Their results revealed that the application of 1.1% NaF gel on permanent teeth produced a significant increase in F at% in the dental structure leading to a stable Ca/P ratio.…”