Effect of bleaching on sound enamel and with early artificial caries lesions using confocal laser microscopy

The aim of this study was to evaluate effect of bleaching agents on sound enamel (SE) and enamel with early artificial caries lesions (CL) using confocal laser scanning microscopy (CLSM). Eighty blocks (4 x 5 x 5 mm) of bovine enamel were used and half of them were submitted to a pH cycling model to induce CL. Eight experimental groups were obtained from the treatments and mineralization level of the enamel (SE or CL) (n=10). SE groups: G1 - unbleached (control); G2 - 4% hydrogen peroxide (4 HP); G3 - 4 HP containing 0.05% Ca (Ca); G4 - 7.5% hydrogen peroxide (7.5 HP) containing amorphous calcium phosphate (ACP). CL groups: G5 - unbleached; G6 - 4 HP; G7 - 4 HP containing Ca; G8 - 7.5 HP ACP. G2, G3, G6, G7 were treated with the bleaching agents for 8 h/day during 14 days, while G4 and G8 were exposed to the bleaching agents for 30 min twice a day during 14 days. The enamel blocks were stained with 0.1 mM rhodamine B solution and the demineralization was quantified using fluorescence intensity detected by CLSM. Data were analyzed using ANOVA and Fisher’s tests (α=0.05). For the SE groups, the bleaching treatments increased significantly the demineralization area when compared with the unbleached group. In the CL groups, no statistically significant difference was observed (p>0.05).The addition of ACP or Ca in the composition of the whitening products did not overcome the effects caused by bleaching treatments on SE and neither was able to promote remineralization of CL.

Download Full-text

Effect of a Bioactive Glass Ceramic on the Control of Enamel and Dentin Erosion Lesions

Brazilian Dental Journal ◽

10.1590/0103-6440201601524 ◽

2017 ◽

Vol 28 (4) ◽

pp. 489-497 ◽

Cited By ~ 4

Author(s):

Michelle Alexandra Chinelatti ◽

Camila Tirapelli ◽

Silmara Aparecida Milori Corona ◽

Renato Goulart Jasinevicius ◽

Oscar Peitl ◽

...

Keyword(s):

Bioactive Glass ◽

Glass Ceramic ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Cross Sectional ◽

Surface Loss ◽

And Control ◽

Bovine Enamel ◽

Caries Lesions

Abstract This study evaluated the effect of a bioactive glass ceramic for the control of erosion and caries lesions. Fragments (n=10) of bovine enamel and root dentin received daily application of different treatments (Biosilicate; Acidulated Phosphate Fluoride- APF; Untreated - control) during the performance of erosive cycles. Surfaces were analyzed with 3D optical profilometry to quantify the superficial loss in four periods (1, 7, 14 and 21 days), as well as the lesion depth with confocal laser scanning microscopy. For caries progression assessment, initial Knoop microhardness was measured on enamel bovine fragments. Initial carious lesions were developed and specimens were divided into three groups (n=10), according to the daily topical application (Biosilicate; APF; no application - control), during the de-remineralization cycles for 14 days. Final microhardness was obtained to calculate the change of surface microhardness. Subsurface demineralization was analyzed using cross-sectional microhardness (depths 10, 30, 50, 70, 90, 110 and 220 µm). Data were tested using ANOVA and Tukey’s test (a=5%). Results of erosive evaluation showed that Biosilicate promoted the lowest (p<0.05) values of surface loss, regardless of time, for both enamel and dentin; APF promoted lower (p<0.05) surface loss than control; analyzing different periods of time, APF did not show difference (p>0.05) between 14 and 21 days of demineralization. Results of enamel caries assessment showed that Biosilicate resulted in higher (p<0.05) surface and subsurface microhardness than both APF and control-applications. It may be concluded that Biosilicate application showed a higher potential to reduce surface loss and development of erosion and caries lesions.

Download Full-text

Use of confocal laser scanning microscopy and a computer model to understand ink cavitation and filamentation

TAPPI Journal ◽

10.32964/tj9.10.7 ◽

2010 ◽

Vol 9 (10) ◽

pp. 7-15

Author(s):

HANNA KOIVULA ◽

DOUGLAS BOUSFIELD ◽

MARTTI TOIVAKKA

Keyword(s):

Laser Scanning ◽

Confocal Laser Scanning Microscope ◽

Laser Scanning Microscopy ◽

Confocal Laser Scanning ◽

Confocal Laser ◽

Print Quality ◽

Length Scale ◽

Offset Printing ◽

Significant Difference ◽

Printing Speed

In the offset printing process, ink film splitting has an important impact on formation of ink filaments. The filament size and its distribution influence the leveling of ink and hence affect ink setting and the print quality. However, ink filaments are difficult to image due to their short lifetime and fine length scale. Due to this difficulty, limited work has been reported on the parameters that influence filament size and methods to characterize it. We imaged ink filament remains and quantified some of their characteristics by changing printing speed, ink amount, and fountain solution type. Printed samples were prepared using a laboratory printability tester with varying ink levels and operating settings. Rhodamine B dye was incorporated into fountain solutions to aid in the detection of the filaments. The prints were then imaged with a confocal laser scanning microscope (CLSM) and images were further analyzed for their surface topography. Modeling of the pressure pulses in the printing nip was included to better understand the mechanism of filament formation and the origin of filament length scale. Printing speed and ink amount changed the size distribution of the observed filament remains. There was no significant difference between fountain solutions with or without isopropyl alcohol on the observed patterns of the filament remains.

Download Full-text

Micromorphological analysis and bond strength comparison of two adhesives for different degrees of dental fluorosis

10.21203/rs.3.rs-16637/v3 ◽

2020 ◽

Author(s):

Shuangfeng Liu ◽

Yanxia Zhu ◽

Tana Gegen

Keyword(s):

Shear Strength ◽

Bond Strength ◽

Bonding Strength ◽

Laser Scanning ◽

Dental Fluorosis ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Cohesive Failure ◽

Bonding System ◽

Significant Difference

Abstract The objective of this study was to analyze morphologically the all-etching bonding system and self-etching bonding system for enamel with different degrees of fluorosis and evaluate the bond strength of each system. Teeth that were indicated for extraction owing to orthodontic or periodontal problems were selected. According to Dean’s index and the Thylstrup-Fejerskov index, 180 extracted teeth were divided into three groups of mild, moderate, and severe dental fluorosis (DF), with 60 teeth in each group. The teeth in each group were randomly divided into two subgroups (n = 30), which were then subjected to the all-etching bonding system (Prime & Bond NT) and self-etching bonding system (SE-Bond). Each group of adhesives was used to bond Z350 universal resin (3M) to the etched dental enamel. Tensile and shear tests were conducted to determine the bond strength. Subsequently, the fractured specimens were investigated using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The Prime & Bond NT was statistically significant for the tensile and shear strength of enamel with mild fluorosis (P < 0.05) but did not exhibit a significant difference for moderate and severe DF (P > 0.05). The SE-Bond was not statistically significant for the tensile and shear strength of mild, moderate, or severe DF (P > 0.05). The SEM and CLSM results reveal that the mild fluorosis enamel crystals were relatively dense, and a small amount of resin remained. The moderate fluorosis enamel crystals were loosely arranged, and the gaps were widened. The severe fluorosis enamel crystals were irregularly arranged. The disorder was aggravated, and the dentinal orifice was exposed by partial enamel exfoliation. The bonding strength of mild fluorosis enamel with the Prime & Bond NT was better than that with the SE-Bond, and cohesive failure was the most common mode of failure. Because there was no difference in the bonding strength of the SE-Bond for different degrees of DF, we recommend the use of the all-etching adhesive system in the clinical treatment of teeth with mild fluorosis.

Download Full-text

Tyrosine phosphorylation following alterations in arteriolar intraluminal pressure and wall tension

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.281.3.h1047 ◽

2001 ◽

Vol 281 (3) ◽

pp. H1047-H1056 ◽

Cited By ~ 15

Author(s):

Timothy V. Murphy ◽

Brian E. Spurrell ◽

Michael A. Hill

Keyword(s):

Tyrosine Phosphorylation ◽

Fluorescence Intensity ◽

Laser Scanning ◽

Time Course ◽

Transmural Pressure ◽

Laser Scanning Microscopy ◽

Intraluminal Pressure ◽

Confocal Laser ◽

Wall Tension ◽

Myogenic Activity

Arterioles respond to increased transmural pressure with myogenic constriction. The present study investigated the role of tyrosine phosphorylation in myogenic activity. Cannulated segments of a rat cremaster arteriole were fixed under pressure, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-phosphotyrosine. Smooth muscle cell fluorescence intensity was measured with the use of confocal laser-scanning microscopy. Anti-phosphotyrosine fluorescence intensity in muscle cells of arterioles maintained at 100 mmHg was reduced by the tyrosine kinase inhibitor tyrphostin A47 (30 μM) and increased by the tyrosine phosphatase inhibitor pervanadate (100 μM). In time-course experiments, anti-phosphotyrosine fluorescence increased slowly (over 5 min) after an acute increase in intraluminal pressure, and was dissociated from myogenic contraction (within 1 min). In contrast, angiotensin II (0.1 μM) caused rapid constriction and increased tyrosine phosphorylation. Anti-phosphotyrosine fluorescence was also pressure dependent (10–100 mmHg). Abolition of myogenic activity, either through removal of extracellular Ca2+, or exposure to verapamil (5 μM) or forskolin (0.1 μM) caused a further increase in anti-phosphotyrosine fluorescence. We conclude that transmural pressure and/or wall tension in arterioles causes increased tyrosine phosphorylation; however, this is not involved in the acute phase of myogenic constriction but may be involved in later responses, such as sustained myogenic tone or mechanisms possibly related to growth.

Download Full-text

Evaluation of four final irrigation protocols for cleaning root canal walls

International Journal of Oral Science ◽

10.1038/s41368-020-00091-4 ◽

2020 ◽

Vol 12 (1) ◽

Author(s):

Qiang Li ◽

Qian Zhang ◽

Xiaoying Zou ◽

Lin Yue

Keyword(s):

Root Canal ◽

Laser Scanning ◽

Laser Scanning Microscopy ◽

Smear Layer ◽

Confocal Laser ◽

Bacterial Survival ◽

Bacterial Inhibition ◽

Layer Removal ◽

Significant Difference ◽

Canal Systems

Abstract The aim of this study was to compare the efficiency of four final irrigation protocols in smear layer removal and bacterial inhibition in root canal systems. Thirty roots inoculated with Enterococcus faecalis were prepared with ProTaper Universal files. The teeth were disinfected by conventional needle irrigation, sonic agitation using the EndoActivator device, passive ultrasonic irrigation, or an M3 Max file. Teeth with no root canal preparation served as blank controls for the establishment of the infection baseline. Teeth with preparation but no final irrigation served as a post-instrumentation baseline. After the final irrigation, the teeth were sectioned in half. One half of each tooth was examined by scanning electron microscopy (SEM) to assess smear layer removal using a five-point scale. The other half was examined by confocal laser scanning microscopy (CLSM) using the LIVE/DEAD BackLight bacterial viability kit to evaluate the depth of bacterial survival in dentinal tubules. SEM analysis revealed no significant difference in smear layer removal throughout the whole canal among the EA, PUI, and M3 Max groups (P > 0.05). CLSM revealed that PUI achieved the greatest bacterial inhibition depth in the coronal ((174.27 ± 31.63) μm), middle ((160.94 ± 37.77) μm), and apical ((119.53 ± 28.49) μm) thirds of the canal (all P < 0.05 vs. other groups). According to this comprehensive SEM and CLSM evaluation, PUI appears to have the best infection control ability in root canal systems.

Download Full-text

Effect of Calcium-phosphate Desensitizers on Staining Susceptibility of Acid-eroded Enamel

Operative Dentistry ◽

10.2341/18-024-l ◽

2019 ◽

Vol 44 (3) ◽

pp. 281-288 ◽

Cited By ~ 2

Author(s):

KY Kyaw ◽

M Otsuki ◽

MS Segarra ◽

N Hiraishi ◽

J Tagami

Keyword(s):

Surface Roughness ◽

Calcium Phosphate ◽

Repeated Measures ◽

Laser Scanning ◽

Artificial Saliva ◽

Color Difference ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Control Group ◽

Before And After

SUMMARY Objective: To investigate the effect of calcium-phosphate–based desensitizers, Teethmate AP paste (TMAP) and Teethmate Desensitizer (TMD) (Kuraray Noritake Dental, Tokyo, Japan), on the prevention of staining on acid-eroded enamel. Methods and Materials: Forty polished enamel samples (4×4×1 mm) from bovine incisors were randomly divided into five groups (n=8). After immersion in 50 mL of 0.5% citric acid (pH 2.5) for 15 minutes to form acid-eroded surfaces, the surfaces were subjected to different treatments with TMAP, TMD, and NaF (0.21% means 950 ppm) for five minutes. Another eroded group was not treated with desensitizer. For the control group, the samples were not eroded or treated. All the samples were stored in artificial saliva (AS) at pH 7.2 for 24 hours at 37°C. The TMAP, TMD, or NaF was reapplied at eight and 16 hours during the 24 hours of storage time. The surface roughness (Sa) was evaluated following ISO 25178 for surface texture using confocal laser scanning microscopy (VK-X 150 series, Keyence, Osaka, Japan) before acid erosion, after acid erosion, and after 24 hours of incubation in AS. Afterward, the color difference was measured with a dental colorimeter (Shade Eye NCC, Shofu, Kyoto, Japan) before and after staining with tea solution. Results: One-way repeated measures analysis of variance showed that acid erosion significantly increased Sa (p<0.001). TMAP- and TMD-treated groups exhibited lower Sa values than the NaF group and the no-desensitizer treatment group. The greatest staining was observed in the NaF group and the no-desensitizer group, while the TMAP and TMD groups significantly decreased the formation of stains. Conclusions: Acid-eroded enamel increased surface roughness and tended to absorb more stains. However, the application of TMAP and TMD moderated the roughness and thus prevented the formation of extrinsic stains.

Download Full-text

Enhanced Bactericidal Efficacy of NaOCl at pH 12 Followed by Acidified NaOCl at pH 6.5 on Enterococcus faecalis Biofilm

Applied Sciences ◽

10.3390/app10176096 ◽

2020 ◽

Vol 10 (17) ◽

pp. 6096

Author(s):

Ronald Wigler ◽

Shlomo Matalon ◽

Tomer Goldberger ◽

Anat Or Lerner ◽

Anda Kfir

Keyword(s):

Contact Time ◽

Laser Scanning ◽

Saline Solution ◽

Volume Ratio ◽

Bactericidal Effect ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Red Fluorescence ◽

Bactericidal Efficacy ◽

Significant Difference

This study aimed to determine the bactericidal efficacy of sequential use of NaOCl pH 12 followed by acidified NaOCl pH 6.5, and compare it to that of either of these NaOCl solutions alone. E. faecalis biofilm was grown on standardized dentine specimens for four weeks. The specimens were randomly divided into four groups: (A) 4 min exposure to 0.9% saline solution (control); (B) 4 min exposure to 4% NaOCl pH 12; (C) 4 min exposure to 4% NaOCl pH 6.5; and (D) 2 min exposure to 4% NaOCl pH 12 followed by 2 min exposure to 4% NaOCl pH 6.5. The bactericidal activity was evaluated after the 4 min of contact time using confocal laser scanning microscopy. The volume ratio of red fluorescence to green and red fluorescence indicated the proportion of dead cells in the biofilm. The percent of dead cells in the saline solution group was significantly lower than those in the other groups. There was no significant difference between NaOCl pH 12 compared to NaOCl pH 6.5. The sequential use of NaOCl pH 12 followed by pH 6.5 significantly increased the percent of dead cells compared to both the samples exposed to either NaOCl pH 12 or pH 6.5. These results show that sequential irrigation protocol had a stronger bactericidal effect than the commonly used NaOCl pH 12.

Download Full-text

Bacterial Colonization in the Marginal Region of Ceramic Restorations: Effects of Different Cement Removal Methods and Polishing

Operative Dentistry ◽

10.2341/15-206-l ◽

2016 ◽

Vol 41 (6) ◽

pp. 642-654 ◽

Cited By ~ 5

Author(s):

SMB Pereira ◽

LC Anami ◽

CA Pereira ◽

ROA Souza ◽

KZ Kantorski ◽

...

Keyword(s):

Laser Scanning ◽

Bacterial Colonization ◽

Resin Cement ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Significant Difference ◽

Ceramic Blocks ◽

Cement Removal ◽

Ceramic Restorations ◽

Marginal Region

SUMMARY This study evaluated the effects of excess cement removal techniques, with or without subsequent polishing, on biofilm formation and micromorphology in the marginal region of the tooth/restoration. From bovine teeth, 96 dentin blocks (4 × 8 × 2 mm) were produced, molded, and reproduced in type IV gypsum, on which 96 pressed ceramic blocks (Vita PM9, Vita Zahnfabrik; 4 × 8 × 2 mm) were produced via the lost wax technique. The dentin blocks and their respective ceramic blocks were cemented with a self-adhesive resin cement (RelyX U200, 3M ESPE), and cement excess was removed from the margin using four different techniques, followed or not by polishing with silicone rubber tips: MBr, removal with microbrush and photoactivation; MBr-Pol, MBr + polishing; Br, removal with brush and photoactivation; Br-Pol, Br + polishing; Photo-Expl, 5 seconds of initial photoactivation, removal with explorer, and final curing; Photo-Expl-Pol, Photo-Expl + polishing; Photo-SB, 5 seconds of initial photoactivation, removal with scalpel, and final curing; and Photo-SB-Pol, Photo-SB + polishing. After 24 hours, the roughness in the marginal region was analyzed using a profilometer (three measurements on each sample). Micromorphological analyses of the region were performed by stereomicroscope and scanning electron microscopy (SEM). Then the samples were contaminated with sucrose broth standardized suspension with Streptococcus mutans, Staphylococcus aureus, and Candida albicans and incubated for a period of 48 hours. The samples were quantitatively analyzed for bacterial adherence in the marginal region by confocal laser scanning microscopy and counting of colony-forming units (CFUs/mL) and qualitatively analyzed using SEM. Roughness data (Ra) were submitted to two-way analysis of variance, Tukey test at a confidence level of 95%, and Student t-tests. CFU, biomass, and biothickness data were analyzed by Kruskal-Wallis, Mann-Whitney, and Dunn tests. The removing technique statistically influenced Ra (MBr, p=0.0019; Br, p=0.002; Photo-Expl, p=0.0262; Photo-SB, p=0.0196) when comparing the polished and unpolished groups. The MBr and MBr-Pol technique differed significantly for CFU/mL values (p=0.010). There was no significant difference in the amounts of biomass and biothickness comparing polished and unpolished groups and when all groups were compared (p>0.05). Different morphological patterns were observed (more regular surface for polished groups). We conclude that margin polishing after cementation of feldspar/pressed ceramic restorations is decisive for achieving smoother surfaces, as the excess cement around the edges can increase the surface roughness in these areas, influencing bacterial adhesion.

Download Full-text

Interspecies Interactions in Dual-Species Biofilms Formed by Psychrotrophic Bacteria and the Tolerance of Sessile Communities to Disinfectants

Journal of Food Protection ◽

10.4315/0362-028x.jfp-19-396 ◽

2020 ◽

Vol 83 (6) ◽

pp. 951-958 ◽

Cited By ~ 1

Author(s):

LEI YUAN ◽

NI WANG ◽

FAIZAN A. SADIQ ◽

GUOQING HE

Keyword(s):

Hydrogen Peroxide ◽

Sodium Hypochlorite ◽

Peracetic Acid ◽

Laser Scanning ◽

Structural Changes ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Interspecies Interactions ◽

Mixed Species ◽

Psychrotrophic Bacteria

ABSTRACT Biofilms on the surface of food processing equipment act as potential reservoirs of microbial contamination. Bacterial interactions are believed to play key roles in both biofilm formation and antimicrobial tolerance. In this study, Aeromonas hydrophila, Chryseobacterium oncorhynchi, and Pseudomonas libanensis, which were previously isolated from Chinese raw milk samples, were selected to establish two dual-species biofilm models (P. libanensis plus A. hydrophila and P. libanensis plus C. oncorhynchi) on stainless steel at 7°C. Subsequently, three disinfectants, hydrogen peroxide (100 ppm), peracetic acid (100 ppm), and sodium hypochlorite (100 ppm), were used to treat the developed sessile communities for 10 min. Structural changes after exposure to disinfectants were analyzed with confocal laser scanning microscopy. The cell numbers of both A. hydrophila and C. oncorhynchi recovered from surfaces increased when grown as dual species biofilms with P. libanensis. Dual-species biofilms were more tolerant of disinfectants than were each single-species biofilm. Peracetic acid was the most effective disinfectant for removing biofilms, followed by hydrogen peroxide and sodium hypochlorite. The results expand the knowledge of mixed-species biofilms formed by psychrotrophic bacteria and will be helpful for developing effective strategies to eliminate bacterial mixed-species biofilms. HIGHLIGHTS

Download Full-text

Influence of Light-curing Parameters on Biofilm Development and Flexural Strength of a Silorane-based Composite

Operative Dentistry ◽

10.2341/14-279-l ◽

2016 ◽

Vol 41 (2) ◽

pp. 219-227 ◽

Cited By ~ 3

Author(s):

E Brambilla ◽

A Ionescu ◽

G Cazzaniga ◽

M Ottobelli

Keyword(s):

Flexural Strength ◽

Laser Scanning ◽

Testing Machine ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Curing Time ◽

Two Samples ◽

Significant Difference ◽

Light Curing ◽

Biofilm Development

SUMMARYObjectives: The aim of this study was to evaluate the differences in biological and mechanical performances of a silorane-based and a methacrylate-based composite. Another aim was to assess the influence of light-curing time and light-curing intensity on in vitro biofilm formation and flexural strength of the two tested composites.Methods: Experiment 1: 432 specimens obtained from a silorane-based composite and from a standard methacrylate-based composite were divided into six groups and light-cured for 10, 20, 30, 40, 60, or 80 seconds, using one of two light-curing intensities, 400 mW/cm2 or 800 mW/cm2. At 24 hours, a monospecific Streptococcus mutans biofilm adherent to the surfaces of the samples was obtained. Then, a colorimetric technique (MTT assay) was used to evaluate the adherent viable biomass. Two samples per group were observed using confocal laser scanning microscopy. Analysis of variance (ANOVA) and Tukey tests were used to analyze the results (p<0.05). Experiment 2: 192 bar-shaped specimens were obtained and light-cured as in the previous experiment. A three-point bend test using a universal testing machine was performed to obtain flexural strength values. ANOVA and Tukey tests were used to analyze the results (p<0.05).Results: In experiment 1, a highly significant difference (p<0.0001) in biofilm development was shown between silorane-based and methacrylate-based composites. In fact, the silorane-based composite exhibited better biological performance. Significant differences were also found between the two light-curing intensities (p<0.018) and for curing times (p<0.0001): silorane-based composite light-cured for 80 seconds at 800 mW/cm2 light-curing intensity showed the lowest biofilm development. In experiment 2, a significant difference in flexural strength (p<0.0318) was only found between the different composites. Nevertheless, both resin composites showed flexural strength values in accordance with International Organization for Standardization guidelines even after 10 seconds of light-curing time.Conclusions: Silorane-based composite was less prone to biofilm development compared with a methacrylate-based composite. Acceptable flexural strength values for both composites were obtained after 10 seconds of light-curing time.

Download Full-text