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Brazilian Dental Journal 2022Proanthocyanidin (PA) is a promising dentin biomodifier due to its ability to stabilize collagen fibrils against degradation by matrix metalloproteinases (MMPs);...
Proanthocyanidin (PA) is a promising dentin biomodifier due to its ability to stabilize collagen fibrils against degradation by matrix metalloproteinases (MMPs); however, the most effective protocol to incorporate PA into bonding procedures is still unclear. This study evaluated the effect of dentin biomodification with a PA acid etchant on MMP activity, adhesive interface morphology and resin-dentin microtensile bond strength. Sound extracted human molars were flattened to expose dentin and acid-etched for 15 s according to the groups: EXP - experimental phosphoric acid; EXP+PA - experimental phosphoric acid 10% PA; TE - total-etching system; SE - self-etching system. Samples were restored with composite resin and stored in distilled water (37ºC). MMP activity and interface morphology were analyzed after 24 h by in situ zymography (n=6) and scanning electron microscopy (n=3), respectively. The resin-dentin microtensile bond strength (μTBS) was evaluated after 24 h and 6 months storage (n=6). Significantly higher MMP activity was detected in etched dentin compared with untreated dentin (p<0.05), but no difference among acid groups was found. Resin tags and microtags, indicative of proper adhesive system penetration in dentinal tubules and microtubules, were observed along the hybrid layer in all groups. There was no difference in μTBS between 24 h and 6 months for EXP+PA; moreover, it showed higher long-term μTBS compared with TE and EXP (p<0.05). The results suggest that 15 s of biomodification was not sufficient to significantly reduce MMP activity; nonetheless, EXP+PA was still able to improve resin-dentin bond stability compared with total- and self-etching commercial systems.
Topics: Acid Etching, Dental; Composite Resins; Dental Bonding; Dental Cements; Dentin; Dentin-Bonding Agents; Humans; Materials Testing; Microscopy, Electron, Scanning; Phosphoric Acids; Proanthocyanidins; Resin Cements; Tensile Strength
PubMed: 36043570
DOI: 10.1590/0103-6440202203941 -
Brazilian Oral Research 2020The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by...
The objective of this study was to evaluate the influence of hydrofluoric acid (HF) concentration, etching time, and application of phosphoric acid (PA) followed by neutralization with sodium bicarbonate on the bond strength between a feldspar ceramic and resin cement. Thus, 80 blocks (10 x 12 x 2 mm) of glass ceramic (VM - Vita Mark II - Vita Zahnfabrik) were made and randomly assigned to eight groups (n = 10) according to the factors: HF concentration (5 and 10%), etching time (60 and 120 s), and use of phosphoric acid (PA) (with and without). According to the experimental group, 37% PA (Condac, FGM) was applied after HF etching for 60s. Afterwards, samples were immersed in sodium bicarbonate for 1 min then in an ultrasonic bath in distilled water (5 min) for cleaning. After surface bonding treatment, cylinders (Ø = 2 mm; h = 2 mm) of dual resin cement (AllCem / FGM) were made in the center of each block. The samples were then stored in water (37ºC) for 90 days and submitted to the shear bond test (50 KgF, 1 mm/min). Failure analysis was performed by stereomicroscope and scanning electron microscopy. Data (MPa) were analyzed with 3-way ANOVA and Tukey's test. Only the factor "HF concentration" was significant (p = 0.02). Most failures were of cohesive in ceramic (40%) and mixed types (42.5%). The 10% HF resulted in higher shear bond strength value than the 5% HF. Surface cleaning with phosphoric acid followed by sodium bicarbonate and HF time (60 or 120 seconds) did not influence the resin bond strength to feldspar ceramic.
Topics: Aluminum Silicates; Analysis of Variance; Dental Bonding; Dental Porcelain; Hydrofluoric Acid; Materials Testing; Methacrylates; Microscopy, Electron, Scanning; Phosphoric Acids; Potassium Compounds; Reference Values; Reproducibility of Results; Resin Cements; Shear Strength; Silanes; Surface Properties; Time Factors
PubMed: 32187304
DOI: 10.1590/1807-3107bor-2020.vol34.0018 -
The Journal of Clinical Pediatric... 2017The aim of this systematic review and meta-analysis is to answer the focused question: Does the application of phosphoric acid, Er:YAG laser and air abrasion enamel... (Meta-Analysis)
Meta-Analysis Review
PURPOSE
The aim of this systematic review and meta-analysis is to answer the focused question: Does the application of phosphoric acid, Er:YAG laser and air abrasion enamel conditioning methods previous to the oclusal sealant application in human permanent molars influence the microleakage?
STUDY DESIGN
A literature research was carried out in the Pubmed Medline, Web of Science, Scopus and Cochrane databases using with the MeSH terms and keyword search strategy. A supplemental hand search of the references of retrieved articles was also performed. Inclusion criteria comprised ex vivo studies (extracted teeth) with permanent human teeth that used chemical (phosphoric acid) or mechanical (Er:YAG laser and air abrasion) conditioning methods previous the sealant application. The studies should evaluate microleakage as an outcome. Meta-analysis pooled plot were obtained comparing the microleakage after pre-treatment with phosphoric acid, Er:YAG and air abrasion enamel conditioning for sealant application using RevMan software.
RESULTS
The search resulted in 164 articles, 55 records were excluded because they were duplicated. The analysis of titles and abstracts resulted in the exclusion of 105 studies. Four studies were included in the systematic review and the meta-analysis. According to the risk of bias evaluation, the four studies were considered low risk of bias. The meta-analysis showed that phosphoric acid had lower microleakage than Er:YAG laser (p < 0.001) and air abrasion (p < 0.001), with heterogeinity of I = 0% and I = 71%, respectively. It was not found statistical difference when compared phosphoric acid and phosphoric acid combined with Er:YAG laser and air abrasion (p > 0.05).
CONCLUSION
The evidence supports that the pretreatment with phosphoric acid leads lower microleakage in oclusal sealants than Er:YAG laser and air abrasion.
Topics: Air Abrasion, Dental; Dental Leakage; Dental Materials; Humans; Lasers, Solid-State; Phosphoric Acids; Pit and Fissure Sealants
PubMed: 28422595
DOI: 10.17796/1053-4628-41.3.167 -
L' Orthodontie Francaise Jun 2009Enamel conditioning (elimination of dental plaque and creation of an irregular surface) is an essential step before bonding of orthodontic brackets. The most popular...
Enamel conditioning (elimination of dental plaque and creation of an irregular surface) is an essential step before bonding of orthodontic brackets. The most popular procedure in our practice is bonding with resin which requires enamel etching in order to get enough shear bond strength. Many studies have tried to evaluate the effects of enamel bonding using the acid-etching procedure as well as the changes caused by detachment of brackets. Thanks to the development of other adhesives such as glass ionomer cements which chemically bind to the enamel, new enamel conditioning methods appeared, in particular sandblasting with aluminium oxide particles. This technique is a mechanical preparation of the tooth that avoids the harmful effects of acid products. By suitably choosing the parameters of sandblasting (pressure, time and quantity of powder), enamel loss is lower than with the acid-etch procedure and the surface of the enamel seems less affected. However the bond strength remains superior to the values required for treatment. The presented results indicate that enamel sandblasting can be considered as an alternative for the acid-etching technique currently used in orthodontic practice because it creates sufficient strength and respects enamel thickness better.
Topics: Acid Etching, Dental; Acrylic Resins; Aluminum Oxide; Dental Bonding; Dental Enamel; Dental Materials; Enamel Microabrasion; Humans; Malates; Microscopy, Electron, Scanning; Orthodontic Appliances; Phosphoric Acids; Stress, Mechanical; Surface Properties; Tooth Preparation
PubMed: 19552877
DOI: 10.1051/orthodfr/2009012 -
Antiviral Chemistry & Chemotherapy 2018Following the first report on the nucleoside phosphoramidate (ProTide) prodrug approach in 1990 by Chris McGuigan, the extensive investigation of ProTide technology has... (Review)
Review
Following the first report on the nucleoside phosphoramidate (ProTide) prodrug approach in 1990 by Chris McGuigan, the extensive investigation of ProTide technology has begun in many laboratories. Designed with aim to overcome limitations and the key resistance mechanisms associated with nucleoside analogues used in the clinic (poor cellular uptake, poor conversion to the 5'-monophosphate form), the ProTide approach has been successfully applied to a vast number of nucleoside analogues with antiviral and anticancer activity. ProTides consist of a 5'-nucleoside monophosphate in which the two hydroxyl groups are masked with an amino acid ester and an aryloxy component which once in the cell is enzymatically metabolized to deliver free 5'-monophosphate, which is further transformed to the active 5'-triphosphate form of the nucleoside analogue. In this review, the seminal contribution of Chris McGuigan's research to this field is presented. His technology proved to be extremely successful in drug discovery and has led to two Food and Drug Administration-approved antiviral agents.
Topics: Amides; Antiviral Agents; Humans; Microbial Sensitivity Tests; Molecular Structure; Phosphoric Acids; Prodrugs; Viruses
PubMed: 29792071
DOI: 10.1177/2040206618775243 -
Science (New York, N.Y.) Feb 2021We report the catalytic stereocontrolled synthesis of dinucleotides. We have demonstrated, for the first time to our knowledge, that chiral phosphoric acid (CPA)...
We report the catalytic stereocontrolled synthesis of dinucleotides. We have demonstrated, for the first time to our knowledge, that chiral phosphoric acid (CPA) catalysts control the formation of stereogenic phosphorous centers during phosphoramidite transfer. Unprecedented levels of diastereodivergence have also been demonstrated, enabling access to either phosphite diastereomer. Two different CPA scaffolds have proven to be essential for achieving stereodivergence: peptide-embedded phosphothreonine-derived CPAs, which reinforce and amplify the inherent substrate preference, and C2-symmetric BINOL-derived CPAs, which completely overturn this stereochemical preference. The presently reported catalytic method does not require stoichiometric activators or chiral auxiliaries and enables asymmetric catalysis with readily available phosphoramidites. The method was applied to the stereocontrolled synthesis of diastereomeric dinucleotides as well as cyclic dinucleotides, which are of broad interest in immuno-oncology as agonists of the stimulator of interferon genes (STING) pathway.
Topics: Catalysis; Molecular Structure; Nucleotides, Cyclic; Oligonucleotides; Organophosphorus Compounds; Phosphoric Acids; Phosphorothioate Oligonucleotides; Stereoisomerism
PubMed: 33574208
DOI: 10.1126/science.abf4359 -
Scientific Reports Aug 2022In recent years, there has been a continuous increase in the incidence of urolithiasis, especially in highly developed countries. Therefore, the question arises which...
In recent years, there has been a continuous increase in the incidence of urolithiasis, especially in highly developed countries. Therefore, the question arises which factors specific to these countries may be responsible for the increase in the incidence of this disease. In this article, we try to assess the effect of phosphoric acid, a component of various carbonated drinks, including Coca-Cola, on the nucleation and growth of struvite crystals, which are the main component of infectious urinary stones. The research was carried out in the environment of artificial urine with and without the presence of Proteus mirabilis bacteria. In the latter case, the activity of bacterial urease was simulated by adding an aqueous ammonia solution. The obtained results indicate that phosphoric acid present in artificial urine causes the nucleation of struvite to shift towards a lower pH, which means that struvite nucleates earlier in artificial urine compared to the control test. The amount of struvite formed is the greater the higher the concentration of phosphoric acid. At the same time, as the concentration of phosphoric acid increases, the growing struvite crystals are larger, which is disadvantageous because they are more difficult to remove from the urinary tract along with the urine. For the highest levels of phosphoric acid tested, large dendrites are formed, which are particularly undesirable as they can damage the epithelium of the urinary tract. The effect of phosphoric acid on the nucleation and growth of struvite is explained in base of chemical speciation analysis. This analysis indicates that the MgHCit and MgCit complexes have the main influence on the nucleation and growth of struvite in artificial urine in the presence of phosphoric acid. It should be keep in mind that all these effects of phosphoric acid are possible when the urinary tract is infected with urease-positive bacteria. In the absence of infection, phosphoric acid will not cause struvite to crystallize.
Topics: Carbonated Beverages; Crystallization; Humans; Magnesium Compounds; Phosphates; Phosphoric Acids; Proteus mirabilis; Struvite; Urease; Urine; Urolithiasis
PubMed: 35995826
DOI: 10.1038/s41598-022-18357-8 -
Chemical & Pharmaceutical Bulletin 2021This study aimed to investigate the characteristics of acid-activated bentonite by focusing on its capability of improving the quality of tap water used during wire...
This study aimed to investigate the characteristics of acid-activated bentonite by focusing on its capability of improving the quality of tap water used during wire electrical discharge machining. Raw bentonite (RB) was activated using sulfuric acid, nitric acid, and phosphoric acid solutions with concentrations of 1, 5, and 10 mol/L, respectively. Scanning electron microscopy images, specific surface area, pore volume, cation exchange capacity, X-ray diffraction patterns, and binding energy of RB and acid-activated bentonites were also evaluated. The specific surface area and pore volume of acid-activated bentonites exceeded those of RB. Conversely, the cation exchange capacity of acid-activated bentonites exhibited an opposite trend. The electrical conductivity of tap water was decreased significantly due to bentonite activated with sulfuric acid, nitric acid, and phosphoric acid solution (removal percentage of approximately 31-39%), as compared to that due to RB. Therefore, the relationship between electrical conductivity and the removed concentration of anion/cation ions was evaluated; the correlation coefficient was -0.950 for the experimental condition in this study. Additionally, the amount of magnesium, calcium, potassium, and sodium ions were decreased after the treatment. These results indicated that acid-activated bentonite can be produced from RB via acid activation and that it can be used to decrease electrical conductivity of tap water.
Topics: Bentonite; Electric Conductivity; Nitric Acid; Particle Size; Phosphoric Acids; Quality Control; Solutions; Sulfuric Acids; Water
PubMed: 33390526
DOI: 10.1248/cpb.c20-00703 -
Clinical and Experimental Dental... Oct 2021It is still not fully understood what pretreatment is best for achieving maximum tightness for pit and fissure sealings (PFS).
BACKGROUND
It is still not fully understood what pretreatment is best for achieving maximum tightness for pit and fissure sealings (PFS).
AIM
This study investigated microleakage of PFS placed after etching with phosphoric acid or after the application of self-etching primers/adhesives (SEPA).
DESIGN
131 third molars were assigned to ten groups. In Hel-P, Helioseal® was applied after phosphoric acid etching. In the other groups, SEPA were used (Dyr-AP: Adper™ Prompt™ L-Pop™, Dyract® Seal; Bea: BeautiSealant Primer and Paste; Hel-Exp: Experimental primer, Helioseal®; Hel-Cl: Clearfil™ SE Bond , Helioseal®). Specimens were stored in distilled water at 37°C (28 days), followed by 3500 thermocycles and staining with 5% methylene blue (M) or 5% silver nitrate (S). After methylene blue staining and sectioning, microleakage was assessed light microscopically. During silver nitrate staining, specimens were dissolved by 32% HCl and remaining PFS were evaluated under a SEM.
RESULTS
Tightness, percentage of penetrated area, and maximum dye penetration were best for Hel-P and Hel-Cl (p < 0.05).
CONCLUSIONS
Phosphoric acid etching of enamel and Clearfil™ SE Bond resulted in the best sealing quality. Methylene blue staining allowed the evaluation of more criteria (fissure shape, voids, sealant penetration depth) compared to silver nitrate.
Topics: Acid Etching, Dental; Dental Cements; Dental Enamel; Dental Leakage; Humans; Methylene Blue; Phosphoric Acids; Pit and Fissure Sealants; Silver Nitrate
PubMed: 33829669
DOI: 10.1002/cre2.420 -
Journal of Dairy Science Dec 2020The presence of acids in a lactose-containing system can affect its crystallization. The crystallization kinetics of lactose solutions were investigated as affected by...
The presence of acids in a lactose-containing system can affect its crystallization. The crystallization kinetics of lactose solutions were investigated as affected by lactic, citric, or phosphoric acid at a concentration of 0.05, 1, or 4% (wt/wt) as compared with that of pure lactose. The crystallization behavior of lactose was affected differently by the presence of all 3 acids and was mostly concentration dependent. The presence of 1 and 4% citric or phosphoric acid reduced the crystal yield significantly (≥18%) as compared with that of pure lactose (∼82%). Thermographic analysis of lactose crystals showed that the presence of 1% lactic, 0.05 and 1% citric, and 4% phosphoric acids in the lactose solutions induced the formation of amorphous lactose. X-Ray diffraction analysis revealed that the lactose crystallized mainly into α-lactose monohydrate, stable anhydrous α-lactose, and anhydrous crystals containing α-lactose and β-lactose in a molar ratio of 5:3 and 4:1. Average size of the lactose particles, comprising of several crystallites, declined depending on the type of the acids and their concentration, but size of a single crystallite was not altered. The findings suggested that the lactose crystallization and crystal properties are governed by the lactose-water interactions, which can be influenced by the presence of acids in a concentration-dependent manner.
Topics: Citric Acid; Crystallization; Lactic Acid; Lactose; Phosphoric Acids; Solutions; Spectroscopy, Fourier Transform Infrared; Thermodynamics; Water; X-Ray Diffraction
PubMed: 33069405
DOI: 10.3168/jds.2020-18375