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PubMed1998

Three-dimensional aspects of etched enamel in non-erupted deciduous teeth.

Acid etching with phosphoric acid on the prismless layer of human dental enamel may produce different patterns of dissolution. Consequently, the presence of several patterns of enamel acid conditioning may indicate better or worse formation of resin tags. In this study, the heterogeneous patterns of 35% phosphoric acid conditioning of human non-erupted deciduous teeth were reported. SEM images demonstrated type I, type II and type III aspects reported by Silverstone et al. (Caries Research 1975; 9:373-387), in spite of the etching time used and the surface area (buccal incisal, middle or cervical thirds). These characteristic features on the enamel surface may indicate the convenient use of this technique in deciduous teeth.

Acid Etching, Dental↗
PubMed2001

Acid conditioning combined with single-component and two-component dentin bonding agents.

OBJECTIVE: The purpose of the present study was to compare ethylenediaminetetraacetic acid conditioning and phosphoric acid conditioning of dentin in combination with two principally different commercial dentin bonding systems. METHOD AND MATERIALS: Twenty-one extracted human third molars were used. All teeth were caries free, and no teeth were root filled. In total, 29 pairs of dentin surfaces were obtained from 21 teeth. One dentin surface in each pair was etched with a 32% phosphoric acid gel for 15 seconds, and the opposite surface was etched with a 24% ethylenediaminetetraacetic acid gel for 3 minutes. One experimental group of 15 dentin surface pairs was subsequently bonded with All-Bond 2, a two-component system, and the other group of 14 pairs was bonded with Prime & Bond NT, a one-bottle adhesive. A flowable resin composite was inserted in the experimental cavity and light cured. Shear bond strength testing was performed according to the protocol of the International Organization for Standardization. RESULTS: The combination of conditioning with ethylenediaminetetraacetic acid and bonding with All-Bond 2 was significantly better than all other combinations, providing a shear bond strength that was 61% to 123% greater. CONCLUSION: Use of ethylenediaminetetraacetic acid in combination with All-Bond 2 resulted in a significantly greater bond strength to dentin than did conventional acid etching.

Acid Etching, Dental↗
PubMed2000

Environmental scanning electron microscopy of hydrated conditioned/etched dentine.

Various etchants/conditioners are used during dental treatment to affect or remove the smear layer. The purpose of this study was to evaluate the effect of different treatments on moist dentine, using a field emission environmental scanning electron microscope (FE-ESEM). Twenty freshly extracted, human molar teeth were utilised. The roots and pulps were removed, and the crowns horizontally sectioned with a low speed diamond saw (Isomet) (with cooling in a saline solution) in order to expose superficial dentine. A smear layer was created on these surfaces by using 600 grit silicone carbide paper. Test surfaces were then treated in one of the following ways: 1. 37% phosphoric acid liquid 2. 37% phosphoric acid gel 3. NRC (non-rinse conditioner) without rinsing 4. NRC with rinsing. Shallow grooves were cut on the untreated sides, using a thin diamond bur. This enabled the samples to be split in half when pressure was applied in the grooves. Samples were maintained moist throughout specimen preparation. Samples were examined in the FE-ESEM (Philips XL 30) in such a way that the effect of the treatment could be viewed occlusally, as well as perpendicular to the treated interface. Phosphoric acid liquid and gel removed the smear layer, and demineralised the dentine for approximately 5-10 micrometers. NRC penetrated the smear layer and modified it to a lesser degree. However, washing of the NRC treated surface removed part of the smear layer, and opened up some dentinal tubules. Excellent resolution was possible with the FE-ESEM in both the wet and dry modes.

Acid Etching, Dental↗
PubMedDate not supplied

Microleakage of compomer restorations in primary teeth after preparation with bur or air abrasion.

This study compared the degree of marginal leakage of a compomer in Class V cavities of human primary molars prepared by a conventional dental bur and air abrasion with or without acid etching. Fifty-six non-carious extracted primary molars were randomly divided into four groups (n=14) to be prepared by four techniques: Group-1: Bur followed by acid etching: Class V cavity preparations were placed on the buccal surfaces of each tooth using a high-speed handpiece. The preparations were 1.5-mm deep, 3-mm long and 2-mm wide, with the occlusal margin in enamel and the cervical margin extending 0.5 mm below the cementoenamel junction. The preparations were acid etched with 37% phosphoric acid starting at the enamel margins for 30 seconds and rinsed with water for 20 seconds. The preparations were then restored with Compoglass F. 2-Group 2: Bur: The preparations and the treatment procedures were the same as in Group 1, with the exception of 37% phosphoric acid application. Group 3: Air abrasion followed by acid etching: Class V cavity preparations were placed on the buccal surfaces of each tooth using a handpiece of an air-abrasive system (PrepStart, Danville Engineering). The system was supplied with dry compressed air at 80 psi. In all tests, the air-abrasion system was operated with an 80 degrees-angle handpiece tip and 50-mm aluminum oxide particles. A tip with a 0.38-mm inner diameter was used at a 2-mm distance. The treatment procedures were the same as in Groups 1 and 2. Group 4: Air abrasion: The preparations and treatment procedures were the same as in Group 3, with the exception of 37% phosphoric acid. After finishing the restorations, the teeth were stored in distilled water at 37 degrees C for 24 hours. The samples were thermocycled for 500 cycles between 5 degrees C and 55 degrees C with a dwell time of 30 seconds. The samples were then immersed in 0.5 percent basic fuchsin dye for 24 hours at 37 degrees C. The surface-adhered dye was then rinsed in tap water and the teeth were embedded in a chemically-activated acrylic resin and bisected longitudinally in a mesiodistal direction with a low speed diamond disk. Each section was examined under a stereomicroscope (Nikon, Tokyo, Japan) at 20x magnification. The data were analyzed statistically by Kruskal-Wallis analysis of variance to determine any statistical significant differences in microleakage scores among the groups at a p-value of 0.05. Also, the enamel versus cementum-dentin microleakage scores of each group were compared using z-test at the 0.05 significance level. There was no statistically significant difference among the groups (p>0.05), but a statistical difference between enamel and cementum-dentin surfaces was evaluated (p<0.05).

Acid Etching, Dental↗
PubMed2004

Influence of different dentin etching times and concentrations and air-abrasion technique on dentin microtensile bond strength.

PURPOSE: To determine the influence of different dentin treatments on the microtensile bond strengths of adhesive resins to dentin. METHODS: Fifteen human molars were ground to 600-grit to obtain flat root-dentin surfaces. Five different dentin treatments were evaluated: Group 1--10% phosphoric acid for 30 seconds; Group 2--37% phosphoric acid for 15 seconds; Group 3--air-abrasion for 10 seconds followed by 10% phosphoric acid for 30 seconds; Group 4--air-abasion for 10 seconds followed by 37% phosphoric acid for 15 seconds. The dental adhesive (OptiBond Solo Plus) was applied according to manufacturer's instructions and followed by composite (Z100) application to provide sufficient bulk for microtensile bond testing. All samples were placed in distilled water for 24 hours at 37 degrees C, thermocycled for 500 cycles in distilled water at 10 degrees C and 50 degrees C, and serially sliced perpendicular to the adhesive surface and subjected to tensile forces (0.5 mm/minute). Additional samples were prepared for SEM to observe the adhesive interface. RESULTS: Group 2 exhibited significantly (P < 0.05) lower bond strength values than all other treatments. The bond strengths of the different conditions were (in MPa): Group 1: 43.0 +/- 16.1; Group 2: 29.2 +/- 8.3; Group 3: 48.1 +/- 14.2; Group 4: 41.0 +/- 9.3. The dentin treated with phosphoric acid 37% for 15 seconds showed the lowest values of microtensile bond strength. The results obtained with Groups 1, 3 and 4 were statistically similar.

Acid Etching, Dental↗
PubMed2003

Evidence that acidosis alters the high-affinity dopamine uptake in rat striatal slices and synaptosomes by different mechanisms partially related to oxidative damage.

Several experimental studies have shown that acidosis impairs neurotransmitter uptake processes. The purpose of this study was to determine the mechanism underlying acidosis-induced alterations of the high-affinity dopamine (DA) uptake in rat striatal synaptosomes and slices. Acidosis (pH 5.5) performed either by lactic acid or phosphoric acid induced a decrease in the high-affinity DA uptake in the two striatal models, slices being lesser affected than synaptosomes. Addition of the acid prior to uptake measurement led to a strong reduction of the DA uptake velocity. This early inhibitory effect was completely reversed when acid was removed from the medium by washings. Conversely, when slices and synaptosomes were pre-incubated for different times with each acid, DA uptake remained inhibited in spite of washings. This later inhibition was accompanied by the production of thiobarbituric acid reactive substances, a marker of lipid peroxidation, and was partially prevented by the antioxidant Trolox. Taken together, these results suggest that acidosis, in a degree encountered during ischemia, alters the high-affinity DA uptake by at least two ways: an early and direct effect of H(+) ions on the DA transporters, and subsequently an inhibition partially mediated by free radical damage.

Acidosis↗
PubMed1996

Bond strength to crown and root dentin.

PURPOSE: To investigate (1) the tensile bond strengths of four commercial dentin bonding systems to bovine crown and root dentin and (2) the structure of the hybrid layers for each system bonded to the two dentin substrates. MATERIALS AND METHODS: Superficial surfaces were exposed in bovine crown and root dentin. The teeth were embedded in plaster and a 3 mm diameter bonding area was demarcated. The four bonding systems used were All-Bond 2, Super-Bond D-Liner Plus, Clearfil Liner Bond II, and ProBond. Bonding procedures followed the manufacturers' instructions with the exception of Super-Bond D-Liner Plus where the primer was left in situ for 60 seconds. Tensile bond strengths were tested after 24-hour storage in 37 degrees C deionized water. Specimens were also prepared for SEM observation of the hybrid layer, after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite. RESULTS: Statistically lower bond strengths to crown dentin when compared with root dentin were observed for All-Bond 2, whereas Liner Bond II showed the opposite (P < 0.01). Both ProBond and Super-Bond D-Liner Plus showed no statistical differences between crown and root dentin (P > 0.05). Hybrid layers could be observed for All-Bond 2, Liner Bond II and Super-Bond D-Liner Plus, with no apparent differences between the hybrid layers of crown and root dentin. In the case of ProBond, where the smear layer was not removed during the priming stage, it appeared that the primer had infiltrated and caused hybridization of the smear layer. The differences in bond strength were thought to be related to the different bonding mechanisms of each material, as well as possible variations in the crown and root dentin substrates.

Acid Etching, Dental↗
PubMed2006

Residue formations of phosphorus hydride polymers and phosphorus oxyacids during phosphine gas fumigations of stored products.

With the extent of international usage and the critical role phosphine gas (PH3) plays in commercial pest control, identification of the residual components deposited during fumigation is mandatory. It has been postulated that these infrequent residues are primarily composed of phosphoric acid or reduced forms of phosphoric acid [hypophosphorous acid (H3PO2) and phosphorous acid (H3PO3)], due to the oxidative degradation of phosphine. Using environmental scanning electron microscopy, gas phase Fourier transform infrared spectroscopy, and X-ray fluorescence spectroscopy, the structural elucidation and formation mechanism of the yellow amorphous polyhydric phosphorus polymers (P(x)H(y)) that occur in addition to the lower oxyacids of phosphorus in residues deposited during PH3 fumigations of select tobacco commodities are explored. This research determined that nitric oxide gas (or nitrogen dioxide) initiates residue formation of phosphorus hydride polymers and phosphorus oxyacids during PH3 fumigations of stored products.

Drug Residues↗
PubMed1995

Function of the hybrid zone as a stress-absorbing layer in resin-dentin bonding.

The effects of dentinal surface conditioning with phosphoric acid or with phosphoric acid and subsequent deproteinization by sodium hypochlorite on resin bonding are presented. Bond strengths mediated by the Gluma/Pekafill bonding and restorative system were not affected by the alternative pretreatment methods, while marginal performance of restorations in dentinal cavities was significantly adversely affected by the deproteinization procedure. The resin polymer coupling zone has an important function as a layer that compensates for the curing stresses of the restorative material that act in a wall-to-wall direction.

Acid Etching, Dental↗
PubMed1975

Transformation of some hydroxy amino acids to other amino acids.

It has been observed that beta-hydroxy-alpha-amino acids are transformed into other amino acids, when heated in dilute solutions with phosphorous acid, phosphoric acid or their ammonium salts. It has been shown that as in the case of previously reported glycine-aldehyde reactions, glycine also reacts with acetone to give beta-hydroxyvaline under prebiologically feasible conditions. It is suggested, therefore, that the formation of beta-hydroxy-alpha-amino acids and their transformation to other amino acids may have been a pathway for the synthesis of amino acids under primitive earth conditions.

Amino Acids↗
PubMed2006

Reactivation of inactivated endogenous proteolytic activities in phosphoric acid-etched dentine by etch-and-rinse adhesives.

Auto-degradation of collagen matrices occurs in resin-infiltrated dentine by the slow action of host-derived matrix metalloproteinases. As phosphoric acid-etching inactivates these endogenous enzymes, it is puzzling how hybrid layers created by simplified etch-and-rinse adhesives can degrade in vivo. This study tested the null hypothesis that there are no differences in the relative proteolytic activities of mineralised dentine, acid-etched dentine, and etch-and-rinse adhesive-treated acid-etched dentine. Powdered dentine prepared from extracted human teeth was treated with 17% EDTA, 10% phosphoric acid, or with five simplified etch-and-rinse adhesives that were applied to 10% phosphoric acid-etched dentine. The gelatinolytic activity of the dentine powder was assayed using fluorescein-labelled gelatine. TEM examination of the air-dried, treated dentine powder was performed to confirm the presence of remnant mineralised dentine after acid-etching. 17% EDTA significantly reduced the relative proteolytic activity (73.2%) of the untreated mineralised dentine powder (control), while 10% phosphoric acid-etched dentine exhibited the highest reduction (98.1%). Treating the acid-etched dentine powder with any of the five simplified etch-and-rinse adhesives resulted in the reactivation of the proteolytic activity, with a significant negative linear correlation (P<0.05) between the increases in fluorescence and the corresponding pH values of the adhesives. It is concluded that simplified etch-and-rinse adhesives can reactivate endogenous enzymatic activities in dentine that are previously inactivated by phosphoric acid-etching. The amount of enzyme reactivated may even exceed the original quantity present in untreated mineralised dentine. This provides an explanation for the degradation of hybrid layers after acid-etched dentine matrices are infiltrated with these adhesives.

Dentin↗
PubMed1996

Microleakage of bonding agents with wet and dry bonding techniques.

PURPOSE: To assess the microleakage of Class V preparations restored with three bonding agents using wet and dry bonding. MATERIALS AND METHODS: Cavities were prepared in the buccal and lingual surfaces of extracted human premolar teeth and restored with resin composite after application of the dentin bonding agents, using a wet or dry bonding technique. The teeth were stored for 2 weeks at 37 degrees C, thermocycled, and the restorations examined for leakage using buffered methylene blue as the marker. The teeth were sectioned bucco-lingually through the restorations and the degree of microleakage assessed microscopically. RESULTS: All groups showed leakage at both the dentin and enamel margins. There was no significant difference in leakage at the enamel margins between groups (p > 0.05) and no significant differences in leakage between the wet bonding (P > 0.05) or dry bonding (P > 0.05) procedures. However, when comparing the effects of wet and dry bonding, there was less leakage at the gingival margin in the groups where the bonding agent was acetone-based and wet bonding was used (P < 0.03). There was no significant difference in leakage for Scotchbond Multi-Purpose Plus when either maleic acid or phosphoric acid was used as the etchant (P > 0.05).

Acid Etching, Dental↗
PubMed1996

Effect of mobile phase additives on peptide retention in reversed-phase chromatography with pellicular and totally porous sorbents.

The effect of two mobile phase additives, trifluoroacetic acid and phosphoric acid, on the energetics of peptide retention in reversed-phase chromatography was investigated using Hy-Tach C18 micropellicular and Vydac C4 and C18 totally porous stationary phases. The effect of the relatively low phase ratio of columns packed with micropellicular sorbents was also examined. The logarithmic retention factors, of two model peptides, Ac-RGGGGLGLGK-amide and Ac-RGAGGLGLGK-amide, were evaluated with different columns and additives in a practical range of eluent strength. The dependence of the logarithmic retention factor on the concentration of acetonitrile in the mobile phase was linear in all cases. The higher sensitivity of the retention to the organic modifier concentration in the case of the Hy-Tach C18 column is attributed to the relatively low phase ratio of this column. Pairwise plots of the logarithmic retention factors were linear. The plots of data obtained with the two additives has unit slopes and thus reveal homoenergetic retention behavior. On the other hand data obtained on two different columns manifest homeoenergetic retention, the slopes of plots are different from unity. The analysis has yielded consistent results and validated the assumption that the retention free energy can be divided into two components arising from mobile phase and stationary phase contributions. The approach also allowed an estimation of the relative phase ratios of the columns and the Vydac C18 column was found to have an 3 and 8 times higher phase ratio than the Vydac C4 and the Hy-Tech C18 column, respectively.

Acetonitriles↗
PubMed1991

[A study on the effectiveness of three common stabilizers of peracetic acid].

This paper reports the effectiveness of 0.1% (W/V) quinoline-8-ol, 0.5% (V/V) phosphoric acid and 0.5% (W/V) sodium pyrophosphate as stabilizers of stock solutions on peracetic acid. The three solutions were put separately as stabilizers into stock solutions of peracetic acid in the laboratory. They were stored at room temperature for approximately one year, and the percent of peracetic acid content was determined at regular intervals. Also, we made studies on different concentrations of phosphoric acid for different prescriptions of peracetic acid. The results show that 0.1%, 0.3% and 0.5% (V/V) phosphoric acid and 0.5% (W/V) sodium pyrophosphate were not effective stabilizers for the stock solutions of peracetic acid. Therefore, phosphoric acid or sodium pyrophosphate is not an effective stabilizer in stockpiling stock solutions of peracetic acid.

Diphosphates↗
PubMed1994

Repair of glass ionomer cements--methods for conditioning the surface of the cement to achieve bonding.

Two chemically different glass ionomer cements (Ketac Fil and ChemFil II Caps) and three different methods of conditioning the surface for repair were evaluated. Specimens of each material were prepared, aged and sectioned. The cut surfaces were treated with either phosphoric acid, polyacrylic acid or a combination of phosphoric acid followed by polyacrylic acid. Freshly mixed glass ionomer cement was injected against the treated surface and allowed to set under simulated intra-oral conditions. The specimens were then tested to failure in flexion after 7 days storage. The flexural strength of the repaired specimens was compared with that of control specimens of the same materials. The flexural strength of the repaired specimens was less than that of the controls. Treatment of the fractured surface with polyacrylic acid produced the weakest repair, and the use of phosphoric acid as the conditioning agent produced repaired specimens approximately 80% of the strength of the controls.

Acid Etching, Dental↗
PubMed1997

Bonding of composite resin using different enamel etchants.

Bonding systems make use of different types and concentrations of enamel etchants. The purpose of this in vitro investigation was to determine the shear bond strength of composite resin to etched enamel using different enamel etchants. The following etchants were used: 35 per cent phosphoric acid for 30 seconds, (Group 1, control), 10 per cent phosphoric acid for 20 seconds (Group 2), 10 per cent maleic acid for 15 seconds (Group 3), 65 per cent phosphoric acid for 30 seconds (Group 4) and 10 per cent citric acid/3 per cent ferric chloride for 30 seconds (Group 5). Composite (Z100) stubs were bonded to the adhesively treated etched enamel surfaces using a rubber split mould. The bonded specimens were stored in distilled water for 24 hours before they were stressed to failure using a shear load in an instron testing machine. Data were analysed statistically (Student-t-test). The micromorphology of the enamel etched with the different etchants was also evaluated in a SEM. Shear bond strength (MPa) for the different groups were as follows: group 1 (23.9), group 2 (18.9), group 3 (18.0), group 4 (20.4) and group 5 (15.6). Ten per cent maleic acid, 10 per cent phosphoric acid and 10 per cent citric acid/3 per cent ferric chloride demonstrated lower enamel bond strengths than conventional 35 per cent phosphoric acid.

Acid Etching, Dental↗
PubMed2001

Effect of antimicrobial agents on the micromorphology of primary dentin.

The use of disinfectants on the dentin surface contributes to superficial cleaning and removal of remaining microorganisms of the carious process. However, the effect of these agents on the adhesion of resin materials to the dentin surface of primary teeth has not been established. This study evaluated the dentin micromorphological effects due to the use of antimicrobial agents in the different depths of dentin. Twenty-five buccal surfaces of primary molars were prepared from the sectioned teeth, ground flat and polished with silicon carbide paper of different grits. The surfaces were treated with 32% phosphoric acid with benzalkonium chloride (Bisco), 35% phosphoric acid gel (3 M), 3% benzalkonium chloride solution by itself or 10% maleic acid. All agents were applied for 15 seconds on the dentin surface. The samples were washed with distilled water, dried and coated with gold for observation of the dentin surface with the scanning electron microscope. The samples were subdivided according to the dentin depth in upper, middle and lower areas. The following was observed: presence of smear layer, opening of the dentin tubules, and inter and intratubular dentin morphology. The effects of the antimicrobial agents were compared in the different depths of the dentin. The results demonstrated that the surface conditioned with 3% benzalkonium chloride solution presented few disclosed dentin tubules. The use of the 32% phosphoric acid with benzalkonium chloride completely removed the smear layer and increased the diameter of the dentin tubule openings. The 35% phosphoric acid totally exposed the tubules in the upper area of the analyzed surface but partially exposed them in the middle and lower areas. The 10% maleic acid totally removed the smear layer, left all the tubules opened and conditioned the intertubular dentin. It was concluded that in the different depths of the dentin surface, conditioning with 10% maleic acid in primary teeth showed the most consistent micromorphological characteristics compared to the other agents used in this study.

Acid Etching, Dental↗
PubMed1985

Reversed-phase high-pressure liquid chromatography of arachidonic acid metabolites formed by cyclooxygenase and lipoxygenases.

High-pressure liquid chromatography is required to resolve the complex mixtures of arachidonic acid metabolites synthesized by many tissues. We have investigated some of the factors which affect the retention times of these substances in reversed-phase HPLC on columns of 5-micron octadecylsilyl silica. There are considerable differences in selectivity between mobile phases based on methanol and those based on acetonitrile, the latter being much better for cyclooxygenase products. The chromatographic behavior of peptidoleukotrienes (LTC4, LTD4, and LTE4) is quite different from that of other arachidonic acid metabolites which do not contain amino acids. Addition of phosphoric acid to the mobile phase results in very long retention times for peptidoleukotrienes. Very low concentrations of trifluoroacetic acid have effects similar to that of phosphoric acid, but as its concentration is raised, the retention times of peptidoleukotrienes decrease, whereas those of other arachidonic acid metabolites are unaffected. Changing the concentration of acetonitrile in the mobile phase also affects the retention times of peptidoleukotrienes differently from those of other metabolites. This information has been used to devise simple linear gradients which separate most of the major cyclooxygenase and lipoxygenase products of arachidonic acid metabolism.

Arachidonic Acid↗