ATR-FTIR, EDS and SEM evaluations of enamel structure after treatment with hydrogen peroxide bleaching agents loaded with nano-hydroxyapatite particles

Abstract

Background Tooth whitening is one of the most requested dental treatments, but it still presents some side effects. Indeed, the bleaching agent can generate patients’ discomfort and dental hard tissue damages, not achieving an efficient and long-lasting treatment with optimum whitening effect. To overcome these limitations, the bleaching agents containing nano-hydroxyapatite can represent a reliable solution to avoid these detrimental effects. Methods In this study, human third molars were treated with commercial bleaching agents, containing nano-hydroxyapatite (nHA) and 6% (at-home treatment), 12% and 18% (in-office treatments) of hydrogen peroxide (HP), named respectively G1, G2 and G3. The results were evaluated descriptively and analytically using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDS), comparing the treated groups with a commercial gel containing 10% carbamide peroxide (CONV) and with a non-treated control group (CTRL). Results ATR-FTIR analysis revealed a similar composition in carbonates and phosphates for CTRL, G1 and G2 groups, which showed no significant differences in their spectral profiles; an increased amount of organic matter was found in G3, while CONV displayed an intermediate behavior. SEM analysis did not highlight significant changes in the enamel microstructure of G1 and CONV when compared to CTRL; the pattern observed in G2 presented a slight increase of enamel irregularities, while G3 displayed a partial removal of the aprismatic layer and microporosities. No evident effects due to nHA were observed in the structure of the hydroxyapatite component of G1, G2 and CONV, if compared to CTRL, while G3 showed a slight loss of crystallinity. In all groups, EDS identified slight changes in the concentration of chemical elements O and Ca, while the Ca/P ratio was similar when compared to CTRL. Conclusion The obtained results suggest that the application of the tested commercial bleaching agents, with a concentration of HP up to 12%, does not alter the morphological and chemical composition of the enamel surface and maintains its crystallinity.

A Comparative Evaluation of Nanohydroxyapatite-Enriched Hydrogen Peroxide Home Bleaching System on Color, Hardness and Microstructure of Dental Enamel

“…nHA is an adjunct to bleaching agents, which aids in limiting the side effects caused by tooth whitening. To date, only a few scientific articles are available about the potential beneficial effect of nHA enriched HP when used for at-home bleaching treatment [ 13 , 26 , 27 ].…”

“…After the surgical extraction, teeth were washed in an ultrasonic bath with distilled water for 2 min in order to remove the blood and biological remains. Then, they were carefully examined to exclude the presence of lesions and decays, including hypoplastic defects and cracks [ 13 ]: teeth exhibiting any of these features were excluded. Selected teeth were stored in a 0.5% ( w/w ) chloramine solution (NH 2 Cl).…”

“…The addition of nano-hydroxyapatite (nHA) to the bleaching agents has been introduced as an attempt to address these problems. [ 13 ]. Indeed, the HA is the primary component of bone and teeth [ 14 ], and it is one of few materials that can facilitate the repairing or substituting of hard tissues [ 15 ].…”

Comparative In Vitro Studies on the Effect of Bleaching Agents on Dental Structures in Healthy and Predialysis Patients

“…Forty teeth were included in the current study, maxillary and mandibular teeth, extracted due to orthodontic or periodontal reasons, from patients aged between 18 and 30 years old [4,5]. Half of the teeth were collected from patients with chronic renal failure, predialysis, and half from healthy patients.…”

Vibrational Imaging Techniques for the Characterization of Hard Dental Tissues: From Bench-Top to Chair-Side

“…Indeed, FTIR was used to track the polymerization kinetics of dental resin composites [24][25][26][27] and adhesives [28,29]. Furthermore, the IR technique was exploited to determine the effects of materials containing nanohydroxyapatite on the enamel surface [30,31], to analyze new generation biomimetic materials mimicking the mineral organic dentin and enamel complex [32], and to characterize implant materials, biopolymers, ceramics, and resin nanocomposites [33][34][35]. Regarding RMS, its applicative potential in the dental field has not yet been fully exploited, even if recent results suggest a promising use of this technique for the characterization of hard dental tissues, also for diagnostic purposes [13,36].…”