Evaluation of the effectiveness of micro-Raman spectroscopy in monitoring the mineral contents change of human enamel in vitro

Investigation of the protective suitability of a dental fluorinated varnish by means of X Ray fluorescence and Raman spectroscopy

BACKGROUND AND AIM

Evaluating the protective effect in human enamel of a fluorinated varnish after enduring a citric acid erosive challenge.

METHODS

An in vitro model was developed considering the intraoral environment, human saliva and acid erosive procedures. The evaluation of the enamel specimens was undertaken through the direct analysis of enamel by means of Raman spectroscopy and Energy Dispersive X Ray Fluorescence (EDXRF). Ten tooth specimens per group were analysed during three stages: 1- before treatment; 2- After varnish (treatment group) or toothpaste (control) application; 3- After citric acid cycle. Additionally, Particle Induced Gamma Ray emission (PIGE) was used to gauge the fluorine uptake by enamel after the application of the varnish (stage 2). Results were presented as mean and standard deviation with ANOVA and Tukey post hoc performed considering a significance level of 0.05.

RESULTS

A significant (p < 0.05) higher Ca levels were detected in treatment group at stage 2 (37.4 ± 0.4 w/w%) and 3 (37.1 ± 0.1) when compared to the control group. After varnish application in treatment group, depolarization ratios were significant lower (p < 0.05) and anisotropy were significant higher (p < 0.05), however no differences were detected in FWHM.

CONCLUSIONS

The use of a fluorinated dental varnish suggests a protective effect for human enamel against dental erosion demineralization process which was detectable in an in vitro model.

In vitro mineral apposition analysis of two Colombian plant extracts on Amelogenesis imperfecta teeth

OBJECTIVE

To determine if native Colombian Piper marginatum Jacq. and Ilex guayusa Loes plant extracts have a remineralizing effect on teeth with Amelogenesis imperfecta in comparison with the commercial products Clinpro-3M and Recaldent™.

MATERIAL AND METHODS

An in vitro study was carried out with 128 human teeth slices (64 healthy and 64 with Amelogenesis imperfecta) on which an initial Raman spectroscopy was performed followed by Raman spectroscopies at 0, 24, 48, and 72 h to determine possible remineralization by observing mineral increase or decrease as a result of P. marginatum Jacq. and I. guayusa Loes extract application in comparison to control substance (Clinpro and Recaldent™) application. Obtained data were analyzed using a bivariate method with a t unidirectional test. Significant differences among groups were determined by an ANOVA with Dunnett post hoc tests.

RESULTS

Native I. guayusa Loes and P. marginatum Jacq. Colombian plants extracts exhibited phosphate and orthophosphate mineral apposition, where P. marginatum Jacq. presented better results.

CONCLUSIONS

Native Colombian I. guayusa Loes and P. marginatum Jacq plant extract might in the future be useful for dental tissue remineralization, as they induced phosphate and orthophosphate mineral apposition, main components of tooth enamel. These types of natural compounds can become an alternative to fluorine, whose ingestion is harmful to the human body.

Study of Demineralized Dental Enamel Treated with Different Fluorinated Compounds by Raman Spectroscopy

BACKGROUND

Current diagnostic methods for enamel caries detection are unable to detect caries lesions (incipient caries lesion) at a very early stage.

OBJECTIVE

This study aims to determine the remineralizing effect of three fluorinated compounds on demineralized subsurface tooth enamel using Raman spectroscopy characterization.

MATERIAL AND METHODS

In this experimental study, sixty impacted 3^rd molars, with intact anatomical crowns recently extracted and without structural defects, were sectioned longitudinally in a mesio-distal direction using a diamond disc, obtaining two working surfaces (buccal and lingual). The 120 working surfaces obtained were immersed for 96 h in a demineralization solution at 37°C in order to demineralize the enamel surface. All samples were randomly divided into three groups (n=30 each) and their surfaces were treated with silver diamine fluoride (SDF), Difluoride silane (DSF), and acidulated phosphate fluoride (APF), and with no treatment undertaken in the control group (CG). The samples were immersed in alternating solutions for demineralization and remineralization at pH 4.4 and pH 7.0, respectively. The results were analyzed with Principal Component Analysis (PCA) in order to determine the variance.

RESULTS

The most important difference (91.7%) is observed in APF group between PCA1 respect to PCA2, followed by DSF (91.5%) and SDF (76.3%) respectively. Therefore, a greater remineralization in the dental enamel can be observed by the three experimental groups.

CONCLUSION

The APF and DSF have the effect of recovering the mineralization of dental enamel, except for the SDF. Functional groups OH^- and PO43- were identified in all subsurface.

A Pilot Study About the Effect of Laser-Induced Fluorescence on Color and Translucency of Human Enamel During Tooth Bleaching

Objective: To probe into the effect of laser-induced fluorescence (LIF) on color and translucency of human enamel during tooth bleaching. Materials and methods: Twenty enamel slabs were randomly assigned to be whitened by acidic 30% hydrogen peroxide (HP), neutral 30% HP, alkaline 30% HP, and distilled water, respectively, monitored by a colorimeter and Raman spectrometer simultaneously. Afterward, the parameter differences of color, translucency, Raman relative intensity, and LIF intensity between baseline and post-treatment of each bleaching cycle were calculated. Results: The results demonstrated that the three bleaching groups resulted in increasingly prominent whitening outcome over time compared with control group, and no statistical difference was detected between them. Accordingly, the bleaching groups also engendered a same decrease tendency in fluorescence intensity (FI). However, less demineralization effect occurred on the enamel surface in neutral HP group. The correlation analysis further excluded the effect of demineralization on all the optical parameters (p > 0.05). Besides, various degrees of dependency were detected between FI and translucency parameter (TP), masking effect (ME), C*ab, W*, b*. In addition, ΔFI was associated with parameters of ΔC*ab, ΔW*, Δb*, ΔE, Δa*, and ΔME. ΔFI% was correlated with ΔC*ab, Δb*, ΔW*, and ΔE values. Conclusions: Thirty percent HP with different pH values could result in same variation tendency of enamel color, translucency, and FI. Plus, FI showed a strong association with enamel color and translucency alteration, which is promising for future application as a nondestructive testing method to evaluate bleaching effect and might be a novel way to investigate tooth bleaching mechanism.

Assessment of the Raman spectroscopy effectiveness in determining the early changes in human enamel caused by artificial caries

Raman maps indicate the changes in enamel affected by the early demineralization process with the use of new parameters.