Adriana Bona Matos

Effect of dental tissue conditioners and matrix metalloproteinase inhibitors on type I collagen microstructure analyzed by Fourier transform infrared spectroscopy

This study aimed to evaluate the chemical interaction of collagen with some substances usually applied in dental treatments to increase the durability of adhesive restorations to dentin. Initially, the similarity between human dentin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR-FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation.

Evaluation of caries-affected dentin with optical coherence tomography

The purpose of this study was to evaluate the degree of demineralization of artificially induced caries-affected human dentin by an in vitro microbiological method. The occlusal surfaces of 6 human molar teeth were abraded until a flat surface was obtained, and the enamel was removed to expose the occlusal dentin surface. These teeth were sectioned in 12 halves in the vestibular-lingual direction and divided into 3 groups according to the period length of the microbiological essay (n = 4): G1, 7 days; G2, 14 days; and G3, 21 days. The surfaces of all specimens were protected by an acid-resistant nail varnish, except for a window where the caries lesion was induced by a Streptoccocus mutans biofilm in a batch-culture model supplemented with 5% sucrose. The specimens were then analyzed by optical coherence tomography (OCT) with a super-luminescent light diode (Λ = 930 nm) with 6.0-µm lateral and longitudinal resolution (in the air). Qualitative and quantitative results (images and average dentin demineralization, respectively) were obtained. The mean demineralization depths were (µm) 235 ± 31.4, 279 ± 14, and 271 ± 8.3 in groups 1, 2, and 3, respectively. In addition, no significant change was observed in the lesion mean depth from 7 days of cariogenic challenge on. In conclusion, OCT was shown to be an efficient and non-invasive method to detect the depths of lesions caused by demineralization. Further, a seven-day demineralization time was considered sufficient for caries-affected dentin to be obtained.

Antimicrobial photodynamic therapy: A promise candidate for caries lesions treatment

BACKGROUND Antibacterial photodynamic therapy (aPDT) is a promising adjunctive therapy to the treatment of caries lesions, mainly in the minimally invasive approach to preserve dental tissue and favor its repair. Here we analyzed both the efficacy of aPDT in reducing the bacterial load in cariogenic biofilms and the indirect effect of noxious components produced by aPDT on the viability of dental pulp cells. METHODS The aPDT protocol was established using 0.025g/mL methylene blue (MB) and 5min pre-irradiation time. A continuous-wave diode laser (660nm, 0.04cm(2) spot size, 40mW, 60s, 60J/cm(2) and 2.4J) was used in punctual and distance modes to excite the MB. The protocol was first tested against Streptococcus mutans (U159) biofilms produced in 96-well microplates, and then evaluated on caries-like affected human dentin discs of three thicknesses. The number of colony forming units (CFU) was compared between groups. Discs were then assembled in metallic inserts to produce an artificial pulp chamber and allow investigation of the indirect effects of aPDT on dental pulp cells by the 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT) assay. Data were analyzed using Students t test or one-way analysis of variance (ANOVA) followed by the Tukeys test at a significance level of 5%. RESULTS Bacterial load reduction was observed in biofilms produced both in the microplates (p<0.05) and on the caries-like affected dentin discs (81.01% or mean reduction of log21.010±0.1548; p=0.0029). The cell viability of aPDT and control group was similar (p>0.05). CONCLUSIONS aPDT may be considered a promise adjunctive therapy for deep carious lesions.

Influence of blood contamination on bond strength of a self-etching adhesive to dental tissues.

PURPOSE The aim of this study was to detect the influence of (1) storage period of heparinized blood, (2) type of blood and presence of contaminant, (3) application mode of cleansing agents, and (4) efficacy of cleansing agents on contaminated enamel and dentin during the adhesion process of a one-step adhesive system. MATERIALS AND METHODS One hundred four human molars were sectioned into halves along the long axis for enamel and dentin tests. Heparinized and fresh blood were obtained from the same donor, applied and dried to maintain a layer of dry blood on the top of samples. The cleansing agents used were hydrogen peroxide, anionic detergent, and antiseptic solution. A one-step adhesive system (Clearfil S3 Bond) was applied on the dental surface, and composite resin cylinders were built up using Tygon tubing molds. After 24 h, the μSBS test (1 mm/min) and fracture analysis were performed. RESULTS There was no statistically significant difference in bond strength values regarding the storage period of heparinized blood and the types of blood. Groups without contamination presented higher bond strengths than contaminated groups. The application mode of the cleansing agents had no influence on bond strength results. There was no statistically significant difference among cleansing agents and they were as effective as a water stream in counteracting the effect of blood contamination. CONCLUSION Heparinized blood can be used as a contaminant for up to one week, and it is a reliable procedure to standardize the contaminant. The cleansing agents can be used without friction. A water stream is sufficient to remove blood contamination from dental tissues, before the application of a one-step adhesive system.

Relationship Between Surface Topography and Energy Density Distribution of Er,Cr:YSGG Beam on Irradiated Dentin: An Atomic Force Microscopy Study

OBJECTIVE The aim of this study was to assess by atomic force microscopy (AFM) the effect of Er,Cr:YSGG laser application on the surface microtopography of radicular dentin. BACKGROUND Lasers have been used for various purposes in dentistry, where they are clinically effective when used in an appropriate manner. The Er,Cr:YSGG laser can be used for caries prevention when settings are below the ablation threshold. MATERIALS AND METHODS Four specimens of bovine dentin were irradiated using an Er,Cr:YSGG laser (λ = 2.78 μm), at a repetition rate of 20 Hz, with a 750-μm-diameter sapphire tip and energy density of 2.8 J/cm(2) (12.5 mJ/pulse). After irradiation, surface topography was analyzed by AFM using a Si probe in tapping mode. Quantitative and qualitative information concerning the arithmetic average roughness (Ra) and power spectral density analyses were obtained from central, intermediate, and peripheral areas of laser pulses and compared with data from nonirradiated samples. RESULTS Dentin Ra for different areas were as follows: central, 261.26 (±21.65) nm; intermediate, 83.48 (±6.34) nm; peripheral, 45.8 (±13.47) nm; and nonirradiated, 35.18 (±2.9) nm. The central region of laser pulses presented higher ablation of intertubular dentin, with about 340-760 nm height, while intermediate, peripheral, and nonirradiated regions presented no difference in height of peritubular and interperitubular dentin. CONCLUSION According to these results, we can assume that even when used at a low-energy density parameter, Er,Cr:YSGG laser can significantly alter the microtopography of radicular dentin, which is an important characteristic to be considered when laser is used for clinical applications.

Nd:YAG laser influence on microleakage of class V composite restoration.

OBJECTIVE The purpose of this research was to evaluate Nd:YAG laser influence on microleakage of class V composite restorations. BACKGROUND DATA There are few studies concerning laser with restorative materials, considering microleakage. One more sent. METHODS Thirty six cavities were prepared and divided into three groups (n = 12): group 1, control; group 2, Nd:YAG laser irradiation before adhesive technique; group 3, Nd:YAG laser irradiation after adhesive technique was used as the single bottle. Adhesive system Nd:YAG laser parameters were 320 microm of fiberoptic; energy/pulse of 40 mJ of energy/pulse; repetition rate of 15 Hz; power of 0.6 W; pulsed and non-contact, 1 mm from the surface; 30 seconds in scanning mode; energy density was 49.76 J/cm(2). Cavities were restored with microhybrid composite. After having used a polishing technique, thermocycling and impermeabilization procedures were performed and specimens were submitted to a microleakage test consisting of immersion in aqueous solution of 50% silver nitrate for 8 h, in the total absence of light. After washing and drying procedures, teeth were embedded to facilitate buccal-lingual vertical sectioning. Microleakage was revealed by light. RESULTS We accomplished Kruskal-Wallis test at 5% level of confidence and observed no statistically significant difference between the tested groups. CONCLUSIONS Based on the obtained results, it was possible to conclude that Nd:YAG laser in the parameters used, has no influence on marginal microleakage in composite restorations, independent of the moment the laser was used.

Laser Phototherapy Enhances Mesenchymal Stem Cells Survival in Response to the Dental Adhesives

Background. We investigated the influence of laser phototherapy (LPT) on the survival of human mesenchymal stem cells (MSCs) submitted to substances leached from dental adhesives. Method. MSCs were isolated and characterized. Oral mucosa fibroblasts and osteoblast-like cells were used as comparative controls. Cultured medium conditioned with two adhesive systems was applied to the cultures. Cell monolayers were exposed or not to LPT. Laser irradiations were performed using a red laser (GaAlAs, 780 nm, 0.04 cm2, 40 mW, 1 W/cm2, 0.4 J, 10 seconds, 1 point, 10 J/cm2). After 24 h, cell viability was assessed by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide reduction assay. Data were statistically compared by ANOVA followed by Tukeys test (P < 0.05). Results. Different cell types showed different viabilities in response to the same materials. Substances leached from adhesives were less cytotoxic to MSCs than to other cell types. Substances leached from Clearfil SE Bond were highly cytotoxic to all cell types tested, except to the MSCs when applied polymerized and in association with LPT. LPT was unable to significantly increase the cell viability of fibroblasts and osteoblast-like cells submitted to the dental adhesives. Conclusion. LPT enhances mesenchymal stem cells survival in response to substances leached from dental adhesives.

Effect of super short pulse Er:YAG laser on human dentin—Scanning electron microscopy analysis

This study evaluated the effect of different pulse widths in the morphological characteristics of human dentin irradiated with Er:YAG in cavity preparation protocols and dentin pretreatment. Dentin discs with 2 mm thickness were obtained from 18 human molars. The experimental groups were composed from two variables: (1) clinical protocol—cavity preparation (E = 200 mJ/20 Hz)—and pretreatment (E = 80 mJ/2 Hz); and (2) pulse duration—50, 300, and 600 μs. This formed six experimental groups (n = 3): G1 (E = 200 mJ/20 Hz/50 μs); G2 (E = 200 mJ/20 Hz/300 μs); G3 (E = 200 mJ/20 Hz/600 μs); G4 (E = 80 mJ/2 Hz/50 μs); G5 (E = 80 mJ/2 Hz/300 μs); G6 (E = 80 mJ/2 Hz/600 μs). The samples were irradiated with the Er:YAG laser by noncontact mode at a focal distance of 7 mm from the target point under continuous water spray (60% water and 40% air). After the irradiation, they were processed for scanning electron microscopy (SEM). Morphological analysis showed an irregular dentin surface, absence of smear layer with opening of the exposure of dentinal tubules and protruding peritubular dentin—without indications of changes for all protocols used. Regardless of the analyzed experimental group, the dentin surface showed a microretentive morphology characteristic of ablation. The G1 and G4 showed a rougher surface when compared to other groups. Finally, we concluded that the pulse width can influence the morphological characteristics of the irradiated dentin tested in different clinical indications. The larger surface irregularity caused by regulation with less pulse width (50 µs) seems more appropriate to get a microretentive pattern necessary for successful adhesives restoration procedures. Microsc. Res. Tech. 78:472–478, 2015.

Influence of Gender, Anxiety and Depression Symptoms, and Use of Oral Contraceptive in Color Perception

OBJECTIVE The color is a psychophysical phenomenon, and much has been studied about its physical components. However, the psychological part is poorly investigated, except for the difference between genders in the literature shows that more men are color deficient than women. Dental students are trained to better understand the differences in color, so we became interested in studying whether psychological variables such as anxiety and depression and use of hormonal contraceptives may interfere with this ability. The aim of this in vitro study was to investigate if factors, such as, hormonal contraceptive use, depressive symptoms, anxiety and quality of life, influence on the ability of color discrimination of dental school students. MATERIALS AND METHODS Sixty-one subjects participated and the following instruments apply: (1) test that consists in the observation of a set of 25 labels (Pantones) with values of known colors, (2) scales of depression, anxiety, and quality of life assessments, and (3) Ishihara test. RESULTS No difference was observed between genders as color perception (p = 0.868). Symptoms of anxiety and depression were significantly more frequent in the female population that showed worse quality of life (p < 0.000) but did not interfere with color perception. Women using hormonal contraceptives had lower color perception than men (p = 0.04). CONCLUSION No difference between the genders in the perception of colors was observed, contrary to common sense that women discriminate more colors than men, but women using hormonal contraceptives showed more difficulty in color perception. CLINICAL SIGNIFICANCE The ability to understand and distinguish color differences is extremely important in clinical dentistry. There could be differences in color perception between men and women that would influence clinical performance.

Er,Cr:YSGG Laser Dentine Conditioning Improves Adhesion of a Glass Ionomer Cement

OBJECTIVE The purpose of this study was to evaluate the bond strength (BS) of different surface treatments, including laser irradiation, between conventional glass ionomer cement (GIC) and dentine. METHODS Eighty-five human third molars were divided into five groups with one of the following treatments: G1- control group, had no treatment; G2, G3, and G4 were treated with Er,Cr:YSGG laser irradiation at 0.5 W, 20 Hz, 25 mJ, 9 J/cm(2) (G2); 1.0 W, 20 Hz, 50 mJ, 18 J/cm(2)(G3); and 1.5 W, 20 Hz, 75 mJ, 27 J/cm(2) (G4); and G5 was treated with GIC liquid, which contains polyacrylic acid. Scanning electron microscopy (SEM) evaluation (n=2) and micro-shear bond strength test (n=15) using the GIC bonded to dentine were performed after 24 h of water immersion. The data were analyzed by one way analysis of variance (ANOVA), according to irradiation protocol (p<0.001). RESULTS G2 specimens presented the highest BS results (in MPa) (10.50±0.84), followed by G1 (4.77±0.59) and G5 (4.26±1.02), which were statistically similar. G3 (3.32±0.39) and G4 (2.94±0.50) demonstrated the lowest BS values, and the difference between these groups was not statistically significant (p>0.001). SEM analysis of G1 revealed that the smear layer covered the entire dentine surface, whereas in G2, G3, and G4, irregular dentine was detected with open dentinal tubules and protruded peritubular dentine. Laser pulses could easily be distinguished in G2 but not in G3 and G4. G5 revealed a thin smear layer with dentinal tubule apertures clearly detectable. CONCLUSIONS Dentine treatment with an Er,Cr:YSGG laser irradiation at a power of 0.5 W increased the BS of conventional GIC.