Intrapulpal Concentration of Hydrogen Peroxide of Teeth Restored With Bulk Fill and Conventional Bioactive Composites

2021 ◽  
Vol 46 (3) ◽  
pp. E158-E170
Author(s):  
DP Silva ◽  
BA Resende ◽  
M Kury ◽  
CB André ◽  
CPM Tabchoury ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rhodamine B ◽  
Laser Scanning ◽  
Gap Analysis ◽  
Oral Care ◽  
Gap Formation ◽  
Resin Modified Glass Ionomer ◽  
Confocal Fluorescence ◽  
Cylindrical Cavities ◽  
Bioactive Composites

SUMMARY This study evaluated intrapulpal concentration and hydrogen peroxide (HP) penetration at the interface of teeth restored with bioactive composites, using conventional or bulk-fill composites. Cylindrical cavities were prepared on the buccal surface of bovine incisor crowns (n=20) and restored with: resin modified glass-ionomer (RMGI, Riva Light Cure, SDI), non-bioactive bulk-fill composite (FB, Filtek Bulk, 3M Oral Care), non-bioactive conventional composite (FZ, Filtek Z350, 3M Oral Care), bioactive bulk-fill composite (AC, Activa BioActive, Pulpedent), and bioactive conventional composite (BII, Beautifil II, Shofu). After 5,000 thermal cycles, restorations (n=10) were exposed to high (35% HP [4 applications of 8 min/session-4 sessions]) or low (9.5% HP [30 min/day-14 days]) concentration bleaching protocols. After the last bleaching application, the HP intrapulpal concentration was determined. Additional teeth were restored, pigmented with rhodamine B solution, and HP penetration around the interface was observed under laser scanning confocal fluorescence microscopy (LSCFM, n=3). The presence of gaps at the interface was observed on replicas of the cross-sectioned samples under scanning electron microscopy (SEM, n=5). Data were submitted to one-way (gap analysis) and twoway analysis of variance (ANOVA; HP intrapulpal concentration) and Tukey test (α=0.05). The LSCFM images were qualitatively analyzed. The restored teeth submitted to 35% HP presented higher HP intrapulpal concentration than teeth submitted to 9.5% HP (p<0.05). No differences in HP intrapulpal concentration was observed among groups (p>0.05) when exposed to 9.5% HP. Lower HP intrapulpal concentration was observed for teeth restored with RMGI exposed to HP 35%, when compared with teeth restored with nonbioactive conventional (FZ; p=0.004) and bulk-fill composites (FB; p=0.01). No gap formation was observed at the outer enamel adhesive interface for all restorative materials. LSCFM images showed that 35% HP promoted greater degradation of rhodamine B at the enamel, except for RMGI. In this context, RMGI promoted lower HP intrapulpal concentration than non-bioactive conventional and bulk-fill composites.

Triacrylamide-Based Adhesives Stabilize Bonds in Physiologic Conditions

2022 ◽  
pp. 002203452110617
Author(s):  
F.S. de Lucena ◽  
S.H. Lewis ◽  
A.P.P. Fugolin ◽  
A.Y. Furuse ◽  
J.L. Ferracane ◽  
...  
Keyword(s):  
Bond Strength ◽  
Cross Sections ◽  
Laser Scanning ◽  
Adhesive System ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Gap Formation ◽  
Bond Stability ◽  
Occlusal Surfaces ◽  
Before And After

In this study, an acrylamide-based adhesive was combined with a thiourethane-based composite to improve bond stability and reduce polymerization stress, respectively, of simulated composite restorations. The stability testing was conducted under physiologic conditions, combining mechanical and bacterial challenges. Urethane dimethacrylate was combined with a newly synthesized triacrylamide (TMAAEA) or HEMA (2-hydroxyethyl-methacrylate; control) to produce a 2-step total-etch adhesive system. Methacrylate-based composites (70 wt% silanized filler) were formulated, containing thiourethane oligomers at 0 (control) or 20 wt%. Standardized preparations in human third molars were restored; then, epoxy replicas were obtained from the occlusal surfaces before and after 7-d storage in water or with Streptococcus mutans biofilm, which was tested after storage in an incubator (static) or the bioreactor (mechanical challenge). Images were obtained from the replicas (scanning electron microscopy) and cross sections of the samples (confocal laser scanning microscopy) and then analyzed to obtain measurements of gap, bacterial infiltration, and demineralization. Microtensile bond strength of specimens stored in water or biofilm was assessed in 1-mm2 stick specimens. Data were analyzed with analysis of variance and Tukey’s test (α = 0.05). HEMA-based materials had greater initial gap measurements, indicating more efficient bonding for the acrylamide materials. When tested in water, the triacrylamide-based adhesive had smaller gaps in the incubator or bioreactor. In the presence of biofilm, there was less difference among materials, but the acrylamide/thiourethane combination led to statistically lower gap formation in the bioreactor. HEMA and TMAAEA-based adhesives produced statistically similar microtensile bond strengths after being stored in water for 7 d, but after the same period with biofilm-challenged specimens, the TMAAEA-based adhesives were the only ones to retain the initial bond strength values. The use of a stable multiacrylamide-based adhesive led to the preservation of the resin-dentin bonded interface after a physiologically relevant challenge. Future studies will include a multispecies biofilm model.

scholarly journals Long-Term Impacts of Selective Logging on Amazon Forest Dynamics from Multi-Temporal Airborne LiDAR

2019 ◽  
Vol 11 (6) ◽  
pp. 709 ◽  
Author(s):  
Ekena Rangel Pinagé ◽  
Michael Keller ◽  
Paul Duffy ◽  
Marcos Longo ◽  
Maiza dos-Santos ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Forest Canopy ◽  
Binary Classification ◽  
Forest Degradation ◽  
Selective Logging ◽  
Ecological Impacts ◽  
Airborne Lidar ◽  
Classification Model ◽  
Amazon Forest ◽  
Gap Formation

Forest degradation is common in tropical landscapes, but estimates of the extent and duration of degradation impacts are highly uncertain. In particular, selective logging is a form of forest degradation that alters canopy structure and function, with persistent ecological impacts following forest harvest. In this study, we employed airborne laser scanning in 2012 and 2014 to estimate three-dimensional changes in the forest canopy and understory structure and aboveground biomass following reduced-impact selective logging in a site in Eastern Amazon. Also, we developed a binary classification model to distinguish intact versus logged forests. We found that canopy gap frequency was significantly higher in logged versus intact forests even after 8 years (the time span of our study). In contrast, the understory of logged areas could not be distinguished from the understory of intact forests after 6–7 years of logging activities. Measuring new gap formation between LiDAR acquisitions in 2012 and 2014, we showed rates 2 to 7 times higher in logged areas compared to intact forests. New gaps were spatially clumped with 76 to 89% of new gaps within 5 m of prior logging damage. The biomass dynamics in areas logged between the two LiDAR acquisitions was clearly detected with an average estimated loss of −4.14 ± 0.76 MgC ha−1 y−1. In areas recovering from logging prior to the first acquisition, we estimated biomass gains close to zero. Together, our findings unravel the magnitude and duration of delayed impacts of selective logging in forest structural attributes, confirm the high potential of airborne LiDAR multitemporal data to characterize forest degradation in the tropics, and present a novel approach to forest classification using LiDAR data.

Cytokinin- and auxin-induced stomatal opening involves a decrease in levels of hydrogen peroxide in guard cells of Vicia faba

2006 ◽  
Vol 33 (6) ◽  
pp. 573 ◽  
Author(s):  
Xi-Gui Song ◽  
Xiao-Ping She ◽  
Jun-Min He ◽  
Chen Huang ◽  
Tu-sheng Song
Keyword(s):  
Hydrogen Peroxide ◽  
Vicia Faba ◽  
Laser Scanning ◽  
Guard Cells ◽  
Laser Scanning Confocal Microscopy ◽  
Stomatal Opening ◽  
Scanning Confocal Microscopy ◽  
Diphenylene Iodonium ◽  
The Relationship ◽  
Exogenous H2o2

Previous studies have shown that cytokinins and auxins can induce the opening of stomata. However, the mechanism of stomatal opening caused by cytokinins and auxins remains unclear. The purpose of this paper is to investigate the relationship between hydrogen peroxide (H2O2) levels in guard cells and stomatal opening induced by cytokinins and auxins in Vicia faba. By means of stomatal bioassay and laser-scanning confocal microscopy, we provide evidence that cytokinins and auxins reduced the levels of H2O2 in guard cells and induced stomatal opening in darkness. Additionally, cytokinins not only reduced exogenous H2O2 levels in guard cells caused by exposure to light, but also abolished H2O2 that had been generated during a dark period, and promoted stomatal opening, as did ascorbic acid (ASA, an important reducing substrate for H2O2 removal). However, unlike cytokinins, auxins did not reduce exogenous H2O2, did not abolish H2O2 that had been generated in the dark, and therefore did not promote reopening of stoma induced to close in the dark. The above-mentioned effects of auxins were similar to that of diphenylene iodonium (DPI, an inhibitor of the H2O2-generating enzyme NADPH oxidase). Taken together our results indicate that cytokinins probably reduce the levels of H2O2 in guard cells by scavenging, whereas auxins limit H2O2 levels through restraining H2O2 generation, inducing stomatal opening in darkness.

Sulfate-enhanced degradation of Rhodamine B in the hydrogen peroxide/hydroxylamine system

2019 ◽  
Vol 17 (4) ◽  
pp. 1831-1837 ◽  
Author(s):  
Shengli Wang ◽  
Linlin Yan ◽  
Xiaohui Guan ◽  
Yanping Jia ◽  
Lianfa Song ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rhodamine B ◽  
Enhanced Degradation

Decolorization of rhodamine B using hydrogen peroxide and H3PW12O40@C photocatalyst synthesizedin situunder ultraviolet irradiation

2013 ◽  
Vol 53 (11) ◽  
pp. 2970-2979 ◽  
Author(s):  
Changchao Zhan ◽  
Mingqiang Zhong ◽  
Feng Chen ◽  
Jintao Yang ◽  
Xiaohua Cao ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Rhodamine B ◽  
Ultraviolet Irradiation

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

2020 ◽  
Vol 83 (6) ◽  
pp. 951-958 ◽  
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

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