Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Phosphorous Acids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources
PubMed1991

Effect of a fluoridated etching gel on enamel morphology and shear bond strength of orthodontic brackets.

The purpose of this study was to compare the enamel morphology and shear bond strengths of orthodontic brackets bonded to enamel etched with a fluoridated or a nonfluoridated phosphoric acid gel. Ten extracted third molars were used for the enamel morphology evaluation. The buccal surfaces were divided in two sections separated by an occlusogingival groove. One side was etched for 60 seconds with a 38% phosphoric acid gel, and the other side was etched with a 60% phosphoric acid gel containing 0.5% sodium fluoride. The specimens were then examined with a scanning electron microscope. For the shear bond strength tests, 30 extracted third molars were used. The buccal enamel surfaces of the mesial cusp were used, and the teeth were randomly divided into two groups of 15 teeth each--group 1, 38% phosphoric acid gel for 60 seconds; group 2, 60% phosphoric acid gel with 0.5% sodium fluoride for 60 seconds. Orthodontic lingual buttons were bonded to the etched surfaces with a composite resin. The results showed that the overall morphologic etching effect was similar in both groups. The mean shear bond strength for group 1 was 11.8 MPa +/- 4.2, and for group 2 it was 16.5 MPa +/- 5.1. This difference was statistically significant (p less than 0.01).

Acid Etching, Dental↗
PubMed1981

gamma-Radiolysis of DNA in oxygenated aqueous solutions: alterations at the sugar moiety.

On gamma-irradiation of DNA in N2O/O2-saturated aqueous solutions alterations at the sugar moiety are observed. In the present study three new lesions were recognized: (i) 2-deoxytetrodialdose bound via a phosphoric acid ester linkage to a (broken) DNA strand, (ii) 2-deoxypentos-4-ulose bound to DNA via one (or two?) phosphoric acid ester linkage(s), and (iii) 2-deoxy-D-erythro-pentose bound to DNA via two phosphoric acid ester linkages. Lesion (i) is directly connected with a DNA strand break. Lesion (ii) might be related to a DNA strand break if bound via only one phosphoric acid ester linkage, or has to be considered as an alkali-labile site if bound via two phosphoric acid ester linkages. Lesion (iii) results from base damage, when the damaged base is hydrolysed from the sugar. This lesion is an alkali-labile site which turns into a strand break on alkali treatment. Attempts have been made to quantify these lesions. A lower limit of sugar damage (including lesions observed in preceding studies, but not lesion (iii) of G = 0.25 has been estimated.

Carbohydrates↗
PubMed1991

Effect of water leaching the adhesion of composite resin to bleached and unbleached bovine enamel.

Standardized cylinders of light-cured composite resin were bonded to the ground labial enamel surface of bovine incisor teeth that had been immersed in double-distilled water for 7 days after having been (a) immersed in hydrogen peroxide for 5, 30, or 60 min, then etched for 60 s with 37% phosphoric acid; (b) immersed in saline for 5, 30, or 60 min, then etched for 60 s with 37% phosphoric acid; (c) etched with 37% phosphoric acid for 60 s, then immersed in hydrogen peroxide for 5, 30, or 60 min; or (d) etched with 37% phosphoric acid for 60 s, then immersed in saline for 5, 30, or 60 min. The enamel surface was washed with water for 1 min and dried with compressed air for 30 s prior to applying the resin. The tooth and applied resin were stored in water at 37 degrees C for 1 day prior to shear and tensile testing. A total of 192 specimens was used, 8 for each enamel preparation mode, for each time period, and for each test. Test values were tabulated and statistically analyzed. Analysis of variance revealed significantly higher bond strength values (p less than 0.005) for hydrogen peroxide-treated as compared with saline-treated specimens. A significant interaction was also noted between test solution and etching order. Scanning electron microscopic examination of failed shear- and tensile-tested specimens revealed no significant solution-related differences in the fracture pattern or the resin quality.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed2006

Dinuclear copper(II) complexes with {Cu2(mu-hydroxo)bis(mu-carboxylato)}+ cores and their reactions with sugar phosphate esters: A substrate binding model of fructose-1,6-bisphosphatase.

Reactions of CuX2.nH2O with the biscarboxylate ligand XDK (H2XDK = m-xylenediamine bis(Kemp's triacid imide)) in the presence of N-donor auxiliary ligands yielded a series of dicopper(II) complexes, [Cu2(mu-OH)(XDK)(L)2]X (L = N,N,N',N'-tetramethylethylenediamine (tetmen), X = NO3 (1a), Cl (1b); L = N,N,N'-trimethylethylenediamine (tmen), X = NO3 (2a), Cl (2b); L =2,2'-bipyridine (bpy), X = NO3 (3); L = 1,10-phenanthroline (phen), X = NO3 (4); L = 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), X = NO3 (5); L = 4-methyl-1,10-phenanthroline (Mephen), X = NO3 (6)). Complexes 1-6 were characterized by X-ray crystallography (Cu...Cu = 3.1624(6)-3.2910(4) A), and the electrochemical and magnetic properties were also examined. Complexes 3 and 4 readily reacted with diphenyl phosphoric acid (HDPP) or bis(4-nitrophenyl) phosphoric acid (HBNPP) to give [Cu2(mu-phosphate)(XDK)(L)2]NO3 (L = bpy, phosphate = DPP (11); L = phen, phosphate = DPP (12), BNPP (13)), where the phsophate diester bridges the two copper ions in a mu-1,3-O,O' bidentate fashion (Cu...Cu = 4.268(3)-4.315(1) A). Complexes 4 and 6 with phen and Mephen have proven to be good precursors to accommodate a series of sugar monophosphate esters (Sugar-P) onto the biscarboxylate-bridged dicopper centers, yielding [Cu2(mu-Sugar-P)(XDK)(L)2] (Sugar-P = alpha-D-Glc-1-P (23a and b), D-Glc-6-P (24a and b), D-Man-6-P (25a), D-Fru-6-P (26a and b); L = phen (a), Mephen (b)) and [Cu2(mu-Gly-n-P)(XDK)(Mephen)2] (Gly-n-P = glycerol n-phosphate; n = 2 (21), 3 (22)), where Glc, Man, and Fru are glucose, mannose, and fructose, respectively. The structure of [Cu2(mu-MNPP)(XDK)(phen)2(CH3OH)] (20) was characterized as a reference compound (H2MNPP = 4-nitrophenyl phosphoric acid). Complexes 4 and 6 also reacted with d-fructose 1,6-bisphosphate (D-Fru-1,6-P2) to afford the tetranuclear copper(II) complexes formulated as [Cu4(mu-D-Fru-1,6-P2)(XDK)2(L)4] (L = phen (27a), Mephen (27b)). The detailed structure of 27a was determined by X-ray crystallography to involve two different tetranuclear complexes with alpha- and beta-anomers of D-Fru-1,6-P2, [Cu4(mu-alpha-D-Fru-1,6-P2)(XDK)2(phen)4] and [Cu4(mu-beta-D-Fru-1,6-P2)(XDK)2(phen)4], in which the D-Fru-1,6-P2 tetravalent anion bridges the two [Cu2(XDK)(phen)2]2+ units through the C1 and C6 phosphate groups in a mu-1,3-O,O' bidentate fashion (Cu...Cu = 4.042(2)-4.100(2) A). Notably, the structure with alpha-D-Fru-1,6-P2 demonstrated the presence of a strong hydrogen bond between the C2 hydroxyl group and the C1 phosphate oxygen atom, which may support the previously proposed catalytic mechanism in the active site of fructose-1,6-bisphosphatase.

Binding Sites↗
PubMed1985

[Acids in coffee. XI. The proportion of individual acids in the total titratable acid].

22 acids in ground roast coffees and instant coffees were determined by GLC of their silyl derivatives (after preseparation by gel electrophoresis) or isotachophoresis. The contribution to the total acidity (which was estimated by titration to pH 8 after cation exchange of the coffee solutions) was calculated for each individual acid. The mentioned acids contribute with 67% (roast coffee) and 72% (instant coffee) to the total acidity. In the first place citric acid (12.2% in roast coffee/10.7% in instant coffee), acetic acid (11.2%/8.8%) and the high molecular weight acids (8%/9%) contribute to the total acidity. Also to be mentioned are the shares of chlorogenic acids (9%/4.8%), formic acid (5.3%/4.6%), quinic acid (4.7%/5.9%), malic acid (3.9%/3%) and phosphoric acid (2.5%/5.2%). A notable difference in the contribution to total acidity between roast and instant coffee was found for phosphoric acid and pyrrolidonecarboxylic acid (0.7%/1.9%). It can be concluded that those two acids are formed or released from e.g. their esters in higher amounts than other acids during the production of instant coffee.

Acids↗
PubMed1979

The influence of charge on phosphatidic acid bilayer membranes.

A complete titration of phosphatidic acid bilayer membranes was possible for the first time by the introduction of a new anaologue, 1,2-dihexadecyl-sn-glycerol-3-phosphoric acid, which has the advantage of a high chemical stability at extreme pH values. The synthesis of the phosphatidic acid is described and the phase transition behaviour in aqueous dispersions is compared with that of three ester phosphatidic acids; 1,2-dimyristoyl-sn-glycerol-3-phosphoric acid, 1,3-dimyristoylglycerol-2-phosphoric acid and 1,2-dipalmitoyl-sn-glycerol-3-phosphoric acid. The phase transition temperatures (Tt) of aqueous phosphatidic acid dispersions at different degrees of dissociation were measured using fluorescence spectroscopy and 90 degrees light scattering. The Tt values are comparable to the melting points of the solid phosphatidic acids in the fully protonated states, but large differences exist for the charged states. The Tt vs. pH diagrams of the four phosphatidic acids are quite similar and of a characteristic shape. Increasing ionisation results in a maximum value for the transition temperatures at pH 3.5 (pK1). The regions between the first and the second pK of the phosphatidic acids are characterised by only small variations in the transition temperatures (extended plateau) in spite of the large changes occurring in the surface charge of the membranes. The slope of the plateau is very shallow with increasing ionisation. A further decrease in the H+ concentration results in an abrupt change of the transition temperature. The slope of the Tt vs. pH diagram beyond pK2 becomes very steep. This is the result of reduced hydrocarbon interaction energy, which was demonstrated by differential scanning calorimetry (Blume, A. and Eibl, H., unpublished data).

Fluorescence Polarization↗
PubMed2004

Fracture strength of all-ceramic crowns luted using two bonding methods.

STATEMENT OF THE PROBLEM: Excellent esthetic quality is one of the major advantages of all-ceramic restorations; however, catastrophic fracture of such restorations is still a disadvantage. Ceramic bonding systems using ceramic primers without the use of hydrofluoric acid have been introduced, but data about the efficiency of these systems are lacking. PURPOSE: This study investigated the influence of 2 bonding procedures on the fracture resistance of low-fusing ceramic and computer aided design-computer aided manufacturing (CAD-CAM) all-ceramic crowns. MATERIAL AND METHODS: Forty-two standardized all-ceramic crowns were fabricated on human maxillary premolars. Seven unprepared maxillary premolars were used as control. Three all-ceramic crown systems were used: 1 low-fusing ceramic (Duceram) and 2 machineable ceramics (Vita Mark II and ProCAD) using the Cerec 3 CAD-CAM system. The intaglio surfaces of fabricated crowns (n=7) were subjected to 2 different conditioning techniques: etching, using 4.9% hydrofluoric acid followed by application of Mirage ABC silane, or cleaning, using 65% phosphoric acid and application of primer (Porcelain Liner-M). The crowns were luted to the teeth using Superbond C&B luting agent. After 24 hours storage in water, specimens were loaded in a universal testing machine with the compressive load applied along the long axis of the specimen at a crosshead speed 1 mm/min until fracture. Fracture loads (N) were recorded. One-way analysis of variance (ANOVA) and the Tukey HSD test (alpha=.05) were used for statistical analysis of the data. RESULTS: The mean fracture load of control specimens (738.3+/-195.3 N) was not significantly different from that of the 2 CAD-CAM crowns (667.7+/-72.3 N, 715.9+/-105.2 N). However, fracture load of natural teeth and the 2 CAD-CAM crowns was significantly higher than the fracture load of the low-fusing ceramic crowns treated with HF acid and silane (465.5+/-101.1 N) and, when cleaned, using phosphoric acid and an application of primer (447.5+/-63.4 N) (P<.05). There was no significant difference in the mean fracture load of each ceramic material when bonded using the 2 different procedures, either treated with HF acid and silane or cleaned using phosphoric acid and application of primer (P>.05). CONCLUSION: The application of a primer (Procelain Liner-M) was an effective method for treating the intaglio surface of all-ceramic crowns before cementation.

Acid Etching, Dental↗
PubMedDate not supplied

Bond strength to primary tooth dentin following disinfection with a chlorhexidine solution: an in vitro study.

PURPOSE: The aim of this study was to determine the effect on shear bond strength of chlorhexidine used as a cavity disinfectant on primary tooth dentin. METHODS: Thirty specimens were randomly divided into 3 groups (N = 10) and treated as follows: (1) in Group I, the dentin was acid etched with a 37% phosphoric acid for 15 seconds, washed and dried; (2) in Group II, a 2% commercial chlorhexidine solution (Cav Clean) was applied for 40 seconds, washed and dried following acid etching for 15 seconds; and (3) in Group III, dentin was treated with a 37% phosphoric acid gel containing 2% digluconate of chlorhexidine (Cond AC) for 15 seconds. In all specimens, the adhesive Single Bond (3M) was applied, and composite cylinders (Filtek Z 250) were built. The specimens were sheared with a universal testing machine (Instron) running at a crosshead speed of 0.5 mm/min, and the results calculated in MPa. The specimens were also observed to record the failure mode. RESULTS: ANOVA analysis revealed that the shear bond strength of Group II (17.99+1.15 MPa) was significantly lower than Group I (19.88+1.02 MPa) and Group III (19.57+1.02 MPa). After debonding, 63% of the specimens presented cohesive failure of the material, 24% adhesive failure and 10% cohesive failure of dentin. CONCLUSIONS: The commercial cavity disinfectant containing 2% chlorhexidine had an adverse effect on Single Bond and produced significantly lower shear bond strength than the etch gel with chlorhexidine and the acid etch alone.

Acid Etching, Dental↗
PubMed2005

Cement from nanocrystalline hydroxyapatite: effect of calcium phosphate ratio.

Nanocrystalline hydroxyapatite (nHA) can be mixed with phosphoric acid to form a brushite cement; a degradable inorganic bone filling material. nHA was precipitated from reactants of calcium to phosphate (Ca/P) ratio 0.8 to 2.0 and mixed with phosphoric acid, which resulted in the formation of a brushite cement. Cement was also formed by mixing microcrystalline calcium phosphates, beta-tricalcium phosphate, hydroxyapatite and tetracalcium phosphate with phosphoric acid solution. Cement produced with nHA was stronger in compression than that formed with crystalline calcium phosphate phases. Setting time, strength and composition of cement produced with nHA was dependant on both the Ca/P ratio of nHA and the concentration of phosphoric acid in cement slurry. Increasing phosphoric acid concentration increased compressive strength whilst reducing the initial setting time of cement. Reducing the Ca/P ratio of nHA precipitation reactants retarded the setting and increased the extent of reaction of cements. This finding was unexpected and suggests that Ca/P ratio may strongly affect dissolution behaviour and this parameter is more important than stoichiometry in determining extent of reaction in this system. This study demonstrated that the wide variation in stoichiometry that may be attained in nanocrystalline apatite may be utilised to change cement performance and setting behaviour.

Bone Cements↗
PubMed2004

Use of a self-etching adhesive on previously etched intact enamel and its effect on sealant microleakage and tag formation.

AIM: This study verified the effects of a self-etching adhesive applied on pre-etched fissures (phosphoric acid 35%) on microleakage, penetration ability and tag formation of a fissure sealant. METHODS: 80 extracted sound human molar teeth were randomly divided into four groups and bisected in two equal parts, forming two subgroups, denominated A and B. Groups 1 and 2 were etched with phosphoric acid for 60 and 40s, respectively. Groups 3 and 4 were etched with phosphoric acid (40 and 20s, respectively) and afterwards treated with Xeno III (20s). All the procedures on sealant placement were performed under 90+/-2% relative humidity. The subgroups A and B were submitted to 1000 and 5000 thermal cycles, respectively. The samples were examined by light microscopy and by confocal laser scanning microscopy (CLSM) after sectioning. Microleakage, penetration ability, fissure type, tag formation quality and tag length were measured. RESULTS: Etching with phosphoric acid for 60s showed statistically significantly lower microleakage when compared to the other groups and significantly better tag formation quality and longer tags compared to 20s H(3)PO(4) plus Xeno III. Fissure type and number of thermal cycles were not significant factors on sealant microleakage. The penetration ability of the sealant in the fissure systems was not influenced by the treatment regimes. Shallow fissures showed a significant better tag formation than deep fissures. No significant difference in the prevalence of fissure types was seen among the groups. CONCLUSION: Etching fissures with phosphoric acid for 60s showed best results. The additional use of Xeno III did not improve fissure sealing under the conditions of this study.

Acid Etching, Dental↗
PubMed2006

An in-vitro investigation into the use of a single component self-etching primer adhesive system for orthodontic bonding: a pilot study.

OBJECTIVE: This pilot study assessed force to debond (N); time, and site of bond failure of a single component self-etching primer (SEP) and adhesive system, Ideal 1 (GAC International Inc., USA) and compared it with the conventional acid etch and rinse regimen using 37% o-phosphoric acid solution and either Transbond XT (3M Unitek) or Ideal 1 adhesive. DESIGN: In vitro laboratory study. SETTING: Bristol Dental Hospital, UK. Sept 2003-Sept 2004. MATERIAL AND METHODS: Nine groups of 20 premolars were bonded using metal orthodontic brackets using three protocols: (1) 37% o-phosphoric acid etch and Transbond XT adhesive; (2) 37% o-phosphoric acid and Ideal 1 adhesive; (3) Ideal 1 SEP and Ideal 1 adhesive. Force to debond and locus of bond failure were determined at three time intervals. RESULTS: Enamel pre-treatment prior to bonding, namely SEP versus conventional etching had no significant effect on the median force to debond with the Ideal 1 adhesive. Similarly, when the enamel was conventionally etched, the adhesive type, namely Ideal 1 or Transbond XT, had no significant effect on the measured force to debond. However, there appeared to be differences in the locus of bond failure: failure predominated at the enamel/adhesive interface for the Transbond XT conventional etch group and at adhesive/bracket interface for the Ideal 1 SEP and adhesive group and the Ideal 1 adhesive conventional etch group. CONCLUSION: These results suggested that the complete Ideal 1 SEP and adhesive system might be successful in vivo leading therefore to a clinical trial. However, implications for clean up time are discussed and improvements to in vitro study designs are advised.

Acid Etching, Dental↗
PubMed1989

Adhesion of a glass ionomer cement to bleached and unbleached bovine dentin.

Cylinders of Fuji Type II glass ionomer restorative cement were bonded to the superficial dentin layer of young bovine incisor teeth that had previously been subjected to 4 different treatments: 1) teeth immersed in 35% hydrogen peroxide for 60 min and etched with 37% phosphoric acid gel for 60 s; 2) teeth immersed in saline for 60 min and etched with 37% phosphoric acid for 60 s; 3) teeth etched with 37% phosphoric acid for 60 s and immersed in 35% hydrogen peroxide for 60 min; or 4) teeth etched with 37% phosphoric acid for 60 s and immersed in saline for 60 min. Specimens were stored in water at 37 degrees for 1 and 7 days, prior to tension and shear testing. A total of 128 teeth were tested: 8 teeth in each group for each day and for each test. Statistical analysis of the results indicated that there was a highly significant reduction in bond strength of the cement when dentin was exposed to hydrogen peroxide as compared with saline. SEM examination of randomly selected fractured test specimens indicated that bond failure was cohesive in nature, suggesting that the hydrogen peroxide treatment adversely affected the setting process of the glass ionomer cement.

Adhesiveness↗
PubMed1995

Shear strength of ceramic brackets bonded to etched or unetched enamel.

The purpose of this study was to compare the shear bond strengths and enamel surface morphology after debonding a polycrystalline ceramic bracket (Transcend 2000) bonded with a light-cured resin cement (Transbond) without enamel etching or by etching for 15 seconds with 10% or 37% phosphoric acid and 10% maleic acid. Forty extracted noncarious human premolars were used. The buccal enamel surfaces were used and the teeth randomly divided in to four groups of 10 teeth each: Group 1: No enamel etching; Group 2: Enamel etching for 15 seconds with 10% phosphoric acid; Group 3: Enamel etching for 15 seconds with 37% phosphoric acid; and Group 4: Enamel etching for 15 seconds with 10% maleic acid. The brackets were bonded to the etched enamel surfaces according to manufacturers' instructions except the etching time variations. All specimens were stored in distilled water for 24 hours and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. The specimens were mounted in dental stone and placed in the Instron at a crosshead speed of 0.5 mm/min using a knife-edged blade. Immediately after debonding, the enamel surface and bracket-enamel interface were evaluated visually and with a stereomicroscope. Representative samples were then examined with the SEM. ANOVA and Student-Newman-Keuls tests were performed. The results (in MPa) were: Group 1:11.83 (+3.9); Group 2: 28.80 (+12.6); Group 3: 26.25 (+5.3); Group 4: 18.06 (+6.9). Groups 2 and 3 were statistically significantly different (p<0.0001) from Groups 1 and 4. Groups 2 vs. 3 or 1 vs. 4 were not statistically different. Debonding occurred mainly at the bracket-resin interface in all groups, except Group 2 which displayed two samples with enamel cohesive failures and two fracturing the bracket. The SEM evaluation revealed that after debonding, the group etched with the 37% phosphoric acid gel had the roughest enamel surface and was the only group to present enamel fractures. Bracket bonding with unetched enamel and enamel etched with 10% phosphoric acid gel should be clinically investigated using the products tested.

Acid Etching, Dental↗
PubMed1991

Evaluation of different staining procedures for the quantification of fibroblasts cultured in 96-well plates.

Comparison of published methods for the quantification of adherent cell numbers by the measurement of absorbance of bound stain indicates a wide variation in their sensitivity. This study aimed at comparing the sensitivities of five different staining procedures (Coomassie brilliant blue G in perchloric acid, Coomassie brilliant blue G in phosphoric acid, methylene blue, crystal violet, and toluidine blue) applied to three separate types of cultured fibroblasts (3T3 cells, Vero cells, and human gingival fibroblasts) at concentrations from 0.125 x 10(4) to 10 x 10(4) per well in 96-well microplates. Absorbance values of Coomassie blue-stained cells were measured in situ. Those of the remaining cells were measured after solubilization of the dye with 1% sodium dodecyl sulfate. All absorbance values were measured using an Elisa reader at 620 or 570 nm for crystal violet. The relationship between cell number and absorbance over the entire cell concentration range was best fitted with quadratic regression analysis, in contrast with the linear relationship described elsewhere. The order of sensitivity of the staining procedures was the same for each cell type: Coomassie blue in perchloric acid less than Coomassie blue in phosphoric acid less than methylene blue less than crystal violet less than toluidine blue. With the latter two stains absorbance values began to plateau at approximately 8 x 10(4) cells per well. However, staining with Coomassie blue in perchloric acid and methylene blue resulted in an almost linear relationship between cell number and absorbance over the entire concentration range tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗
PubMed1991

Photocure bonding agent containing phosphoric methacrylate.

Effective photocure phosphoric methacrylate bonding agents which bonded a dental composite to tooth substrates were proposed. Methacryloyloxydecyl phosphoric acid (MDP) or 2-methacryloyloxyethyl phenyl phosphoric acid (Phenyl-P) was dissolved in triethyleneglycol dimethacrylate (TEGDMA) with camphorquinone (CQ) and N-phenylglycine (NPG). The combination of CQ and NPG was a good visible-light initiator for the polymerization. The highest bond strength was 5 MPa to dentin and 10 MPa to enamel when the adhesive contained Phenyl-P in TEGDMA. Dentin and enamel were recommended for demineralization with an aqueous mixture of 0.3 mol/L EDTA diammonium salt and 0.2 mol/L EDTA ammonium iron salt for generation of better bond strength.

Animals↗
PubMedDate not supplied

Effects of different preparation techniques on the microleakage of compomer and resin fissure sealants.

PURPOSE: The aim of this study was to compare the microleakage of a compomer and resin sealant in vitro using different surface preparation techniques. METHODS: Microleakage of a compomer (Dyract Seal, DeTrey) and a resin sealant (Helioseal F, Vivadent) was investigated on 125 intact third molars. Materials and the surface preparation techniques were: Group 1--phosphoric acid (37%)+Helioseal F; Group 2--AlO2 air abrasion+Helioseal F; Group 3--nonrinse conditioner (NRC)+Prime&Bond+Dyract Seal; Group 4--phosphoric acid+Dyract Seal; Group 5--AlO2 air abrasion+Dyract Seal. RESULTS: Pretreatment with phosphoric acid produced the lowest microleakage scores when applied with compomer and resin fissure sealants and there was no statistical difference (P>.05). CONCLUSIONS: Compomer sealant used with a nonrinse conditioner (NRC) was not as successful as pretreatment with phosphoric acid etching, whereas AlO2 air abrasion pretreatment was ineffective in preventing microleakage in both sealants.

Acid Etching, Dental↗
PubMed1993

SEM analyses of repaired glass-ionomer cements.

This study assessed the nature of the adhesion in repaired glass-ionomer restorative materials. Two chemically different glass-ionomer cements, Ketac Fil and Chemfil II Cap, and three different methods of conditioning the surface for repair were employed. Specimens of each material were prepared and the cut surfaces were then treated with either 35% phosphoric acid, 35% polyacrylic acid or a combination of phosphoric acid followed by polyacrylic acid. Freshly mixed material was injected against these treated surfaces and allowed to set under simulated intraoral conditions. The specimens were tested to failure in flexion after seven days storage. Assessment of the fractured surfaces was then carried out using the scanning electron microscope. The results showed the occurrence of both adhesive and cohesive failure.

Acid Etching, Dental↗
PubMed1996

Adhesion to dentin with resin using sulfinic acid initiator system.

A study was made on the dentin bonding of MMA/PMMA resin using sulfinic acid/BPO/amine polymerization initiator, to examine: 1) the effect of ferric and copper chloride contained in phosphoric acid or citric acid dentin conditioners, and 2) the effect of the addition of acidic monomers to the resin. Tensile bond strength was significantly improved by conditioning dentin with 10% phosphoric acid containing 3% ferric chloride. The citric acid-based conditioners and the addition of the copper salt to the acidic conditioners were less effective in improving bond strength. The mechanism of the improved bond strength is discussed in terms of polymerization promoting action of ferric ion at the dentin-resin interface. For improving bond strength, the presence of a suitable acidic monomer was essential. Its effectiveness depended on the types of acids: Two phosphoric acid ester monomers were effective but methacrylic acid had little effect.

Adhesiveness↗