Ana Maria do Espírito Santo

Mineral distribution and CLSM analysis of secondary caries inhibition by fluoride/MDPB-containing adhesive system after cariogenic challenges.

OBJECTIVE To evaluate the inhibition zone formation (IZ) and mineral distribution along the interface of adhesive systems either containing fluoride and antibacterial primer or not, after chemical and biological artificial caries challenges. METHODS Forty-eight third molars were used. Artificial caries was developed with S. mutans in a 4mm x 4mm area of occlusal dentin surface. Carious dentin was removed and cavities were restored with Adper Scotchbond Multi-Purpose (SBM) and Clearfil Protect Bond (CPB) (n=24). Samples were submitted to secondary caries development by chemical (C) (acidic gel) or biological (B) (S. mutans culture) methods for 5 days. Four groups were tested (n=12): (1) SC (SBM+C); (2) SB (SBM+B); (3) CC (CPB+C); (4) CB (CPB+B). The IZ and outer lesion (OL) formations were analyzed by confocal laser scanning microscopy (CLSM). The distribution of calcium (Ca) and phosphorus (P) content along the interface was analyzed by micro X-ray fluorescence spectrometer by energy-dispersive (microEDX). RESULTS The frequency of IZ formation and mean values of IZ thickness differed among the groups. The CC group presented the lowest OL depth. microEDX analysis showed that CPB had the highest mineral loss by the biological method, but the lowest mineral loss by the chemical method. SC and SB groups showed intermediate values of mineral loss. CONCLUSION The mineral loss along the dentin/restoration interface was affected by the artificial caries method, and hybrid layer formation by adhesive systems used. The adhesive system containing fluoride and antibacterial primer did not prevent secondary caries formation.

Energy dispersive X-ray spectrometry study of the protective effects of fluoride varnish and gel on enamel erosion

Background: Dental erosion is a risk factor for dental health, introduced by todays lifestyle. Topical fluoride applications in the form of varnishes and gel may lead to deposition of fluoride on enamel.

Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 2: energy-dispersive X-ray fluorescence spectrometry study

The effects of laser etching, decontamination, and storage treatments on dentin components were studied by energy-dispersive X-ray fluorescence spectrometry (EDXRF). Thirty bovine incisors were prepared to expose the dentin surface and then divided into two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in aqueous thymol solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ). Samples were analyzed by micro-EDXRF, yielding three spectra for each area (before and after treatment). Surface mappings covering an area of 80x60 points with steps of 20 mum were also performed on selected specimens. The amount of Ca and P in group A specimens decreased significantly (P<0.05) after the acid etching and the CaP ratio increased (P<0.001). Er:YAG laser-etching using lower laser energies did not produce significant changes in dentin components. The mapping data support the hypothesis that acid etching on dentin produced a more chemically homogeneous surface and thus a more favorable surface for the diffusion of adhesive monomers.

Morphological and chemical changes in dentin after using endodontic agents: Fourier transform Raman spectroscopy, energy-dispersive x-ray fluorescence spectrometry, and scanning electron microscopy study

We examine the morphological and chemical changes in the pulp chamber dentin after using endodontic agents by scanning electron microscopy (SEM), Fourier transform Raman spectroscopy (FT-Raman), and micro energy-dispersive x-ray fluorescence spectrometry (μEDXRF). Thirty teeth were sectioned exposing the pulp chamber and divided by six groups (n=5): NT-no treatment; CHX-2% chlorhexidine; CHXE-2% chlorhexidine+17% EDTA; E-17% EDTA; SH5-5.25% NaOCl; SH5E-5.25% NaOCl+17% EDTA. The inorganic and organic content was analyzed by FT-Raman. μEDXRF examined calcium (Ca) and phosphorus (P) content as well as Ca/P ratio. Impressions of specimens were evaluated by SEM. Data were submitted to Kruskal-Wallis and Dunn tests (p<0.05). Differences were observed among groups for the 960 cm(-1) peak. Ca and P content differences were significant (SH5>NT=SH5E>CHX>E>CHXE). CHXE and E presented the highest Ca/P ratio values compared to the other groups (p<0.05). The SEM images in the EDTA-treated groups had the highest number of open tubules. Erosion in the tubules was observed in CHX and SH5E groups. Endodontic agents change the inorganic and organic content of pulp chamber dentin. NaOCl used alone, or in association with EDTA, was the most effective agent considering chemical and morphological approaches.

FT-Raman and energy dispersive X-ray fluorescence spectrometric analyses of enamel submitted to 38% hydrogen peroxide bleaching, an acidic beverage, and simulated brushing.

OBJECTIVE This study aimed to investigate the effects on enamel surface treated with hydrogen peroxide bleaching and acidic soft drink immersion and/or brushing with whitening dentifrices. MATERIALS AND METHODS Fifty-six standardized enamel slabs obtained from labial surfaces of bovine incisors were used. Enamel slabs were ground flat, polished, and randomly assigned to one of seven treatment groups: (1) control, in which no treatment was performed, (2) soft drink immersion, (3) 38% hydrogen peroxide bleaching, (4) simulated toothbrushing with whitening dentifrice, (5) soft drink immersion and bleaching, (6) soft drink immersion, bleaching, and toothbrushing, and (7) bleaching and toothbrushing. The mineral concentration of enamel surfaces was determined before and after treatments by means of Fourier transform (FT)-Raman spectroscopy and energy dispersive x-ray fluorescence spectrometry (EDXRF). Data were statistically analyzed by ANOVA and Tukey test (p < 0.05). RESULTS Raman spectroscopy results indicated that enamel mineral content decreased after all treatments except in group 1, whereas EDXRF results exhibited mineral decrease in groups 3, 4, 5, and 7. CONCLUSION Bleaching alone or in combination with soft drink immersion and brushing decreases enamel mineral content.

Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 1: Fourier transform-Raman study.

The effects of laser etching, decontamination, and storage treatments on dentin components were studied using Fourier transform (FT)-Raman spectroscopy. Thirty bovine incisors were prepared to expose the dentin surface and then divided in two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in thymol aqueous solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ, and total energy of 12 J). Samples were analyzed by FT-Raman spectroscopy; we collected three spectra for each area (before and after treatment). The integrated areas of five Raman peaks were calculated to yield average spectra. The areas of the peaks associated with phosphate content (P<0.001), type I collagen, and organic C-H bonds (P<0.05) were reduced significantly in group A (control). Analyses of samples irradiated with reduced laser energies did not show significant changes in the dentin components. These results suggest that thymol storage treatment is advised for in vitro study; furthermore, 12 J of Er:YAG laser energy does not affect dentin components.

Dental Enamel Irradiated with Infrared Diode Laser and Photo-Absorbing Cream: Part 2—EDX Study

OBJECTIVE The effects of laser-induced compositional changes on the enamel were investigated by energy-dispersive X-ray fluorescence spectrometry (micro-EDX). After cariogenic challenge, we administered treatment of low-level infrared diode laser and a photo-absorbing cream (used to intensify the superficial light absorption). BACKGROUND DATA Dental caries is considered the most prevalent oral disease. A simple and noninvasive caries preventive regimen is treating tooth enamel with a laser, either alone or in combination with fluoride, which reduces enamel solubility and dissolution rates. High power lasers are still not widely used in private practice. Low-power near-infrared lasers may be an alternative approach. Energy-dispersive micro-EDX is a versatile and nondestructive spectroscopic technique that allows for a qualitative and quantitative elemental analysis of inorganic enamel components, such as calcium and phosphorus. MATERIALS AND METHODS Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: 1) control group (CTR-no treatment); 2) infrared laser treatment (L) (lambda = 810 nm, 100 mW/cm(2), 90 sec, 4.47 J/cm(2), 9 J); 3) infrared laser irradiation and photo-absorbing agent (CL); 4) photo-absorbing agent alone (C); 5) infrared laser irradiation and fluoridated photo-absorbing agent (FCL); and 6) fluoridated photo-absorbing agent alone (FC). Samples were analyzed using micro-EDX after two sets of treatments and pH cycling cariogenic challenges. RESULTS The CL group showed statistically significant increases in calcium and phosphorus (wt%) compared with the CTR group. The Ca/P ratio was similar in the FCL and CTR groups. There was a significant laser-induced reduction compared with the CTR group, and there was a possible modification of the organic balance content in enamel treated with laser and cream. CONCLUSION micro-EDX may be able to detect compositional changes in mineral phases of lased enamel under cariogenic challenge. Our results suggest that with a combined laser and photo-absorbing agent (CL) treatment, there was a possible disorganization of organic content in the tooth enamel with hydroxyapatite crystal reordering and reorganization.

Erosion effects on chemical composition and morphology of dental materials and root dentin

Purpose: This work aims to study the erosion on restorative materials and on surrounding dentin. Fifty root dentin samples were obtained from bovine incisors. Methods: Twenty samples were not restored and thirty received cavity preparations. Samples were assigned to five groups: G1, G2: sound dentin (D); G3: composite resin (CR); G4: resin‐modified glass‐ionomer cement (RMGIC); G5: glass‐ionomer cement (GIC). The samples of groups 2–5 were submitted to six cycles (demineralization–remineralization). Samples were analyzed by micro energy‐dispersive X‐ray fluorescence spectrometry (μ‐EDXRF) and by scanning electron microscopy (SEM). Results: Mineral loss was greater in G2 samples than in RMGI > CR > GIC > D (control). SEM images showed pronounced dentin demineralization in groups 2 and 4. The acid erosion has a significant effect on mineral loss (Ca and P) of root dentin without restoration. Conclusions: Composite resin had the best chemical resistance to erosion among all the materials. Fluoride contained in GIC seemed to cause some protection, however, with material degradation. Chemical interaction of tooth‐colored dental materials with root dentin could be assessed by μ‐EDXRF. Microsc. Res. Tech. 75:703–710, 2012.

Micro energy-dispersive X-ray fluoresence mapping of enamel and dental materials after chemical erosion.

Energy-dispersive X-ray fluorescence was employed to test the hypothesis that beverage consumption or mouthwash utilization will change the chemical properties of dental materials and enamel mineral content. Bovine enamel samples (n = 45) each received two cavity preparations (n = 90), each pair filled with one of three dental materials (R: nanofilled composite resin; GIC: glass-ionomer cement; RMGIC: resin-modified GIC). Furthermore, they were treated with three different solutions (S: saliva; E: erosion/Pepsi Twist®; or EM: erosion+mouthwash/Colgate Plax®). It was found that mineral loss in enamel was greater in GICE samples than in RE > RMGICE > RMGICEM > REM > GICEM. An increased percentage of Zr was found in REM indicating organic matrix degradation. Dental materials tested (R, GIC, and RMGIC) were not able to protect adjacent enamel from acid erosion by the soft drink tested. The use of mouthwash promoted protection of enamel after erosion by the soft drink. To avoid chemical dissolution by mouthwashes, protection by resin composites with surface sealants is recommended.

Morphological and Chemical Comparative Analysis of The Human and Bovine Dentin–Adhesive Layer

Micro energy-dispersive X-ray fluorescence spectrometry (µ-EDXRF) and scanning electron microscopy (SEM) were used to evaluate dentin treated with an etch and rinse adhesive (ER) and a self-etch adhesive (SE). Ten human molars (H) and ten bovine anterior teeth (B) were prepared (exposure of dentin and divided in the middle) and allocated into two different adhesion strategy groups per substrate (n=40). µ-EDXRF data and SEM images were obtained before and after treatment. Untreated dentin of both substrates did not differ in terms of Ca (p<0.1503), P (p<0.2986) or Ca/P ratio (p<0.1400). H-SE and B-SE specimens showed reduced P content (p<0.0001; p<0.0002), while H-ER and B-ER specimens showed reduced Ca and P content (p<0.0001; p<0.0001) when compared with untreated specimens. The Ca/P ratio was significantly higher in H-ER and B-ER specimens than in H-SE and B-SE specimens (p<0.0001; p<0.0080). Untreated dentin showed a homogeneous elemental distribution. However, after adhesive treatments, the surface of the dentin showed an irregular demineralization pattern. The resin tags and adhesive layer were shorter in bovine specimens than in human specimens due to morphological differences.