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PubMed2003

An in vitro assessment using transverse microradiography of the effect on mineral loss of etching enamel for in situ studies.

OBJECTIVES: To test the hypothesis that etching enamel with 37% phosphoric acid for 30 s does not lead to detectable mineral loss when measured with transverse microradiography (TMR). DESIGN: An in vitro laboratory investigation. EXPERIMENTAL VARIABLE: Forty bovine incisors were used in the experiment. The crowns of the teeth were covered with acid resistant varnish except for a rectangular area on the labial surface approximately 10 x 12 mm. On the exposed labial surface of 20 teeth an enamel lesion similar to that used in the in situ caries model was induced. Twenty teeth were left without a lesion. The exposed area was divided into three areas of equal size. The control area (C) was covered with acid resistant varnish throughout the experiment. The first experimental area (E1) was etched with 37% phosphoric acid for 30 s and a simulated bracket was bonded to the surface with composite resin. The second experimental area (E2) was left exposed for the remainder of the experiment. The teeth were placed in a demineralizing solution for 24, 48, 72 or 96 h to replicate different cariogenic challenges. OUTCOME MEASURE: Mineral loss as measured with TMR. RESULTS: There were no significant differences in the mineral loss between etched (E1) and etched (C) areas of enamel. There were significant differences in mineral loss between E1 and E2 for the 48 h (p < 0.001) and 72 h (p = 0.001) exposures without a pre-formed enamel lesion. CONCLUSION: There is no detectable mineral loss with TMR when enamel has been etched for 37% phosphoric acid for 30 s. The use of in situ enamel specimens with acid etch retained simulated brackets to investigate demineralization during orthodontics will not significantly affect the outcome compared with unetched specimens.

Acid Etching, Dental↗
PubMedDate not supplied

Microleakage and bond strength of sealant to primary enamel comparing air abrasion and acid etch techniques.

PURPOSE: The objective of this study was to compare the effect of air abrasion (KCP 2000), acid etching (37% phosphoric acid), and the combination of both procedures on the shear bond strength and microleakage of a light-cured pit-and-fissure sealant to the enamel of human primary molar teeth. METHODS: Noncarious extracted human primary molars were randomly divided into 4 groups in preparation for enamel bonding. The enamel surface was treated as follows for each group: (1) group 1 (control group); (2) group 2 (acid etch group); (3) group 3 (KCP [Kinetic Cavity Preparation System] group); and (4) group 4 (KCP and acid etch group). Delton, a light-cured pit-and-fissure sealant, was then applied to the occlusal surface after conditioning. The bonded specimens were maintained in distilled water at 37 degrees C+/-2 degrees C for 7 days, after which they were subjected to thermocycling followed by shear bond testing. Microleakage was determined by immersing the prepared teeth in 50% silver nitrate dye followed by sectioning and calculation of dye penetration. RESULTS: The mean shear bond strength of the KCP+acid etch group exhibited nearly 50% higher bond strength than the acid etch group (P<.01). In addition, specimens bonded to enamel conditioned only with acid etch exhibited bond strengths that were nearly twice that of those conditioned with the KCP system alone. No significant difference was noted between the air abrasion and control groups. CONCLUSIONS: In primary teeth, air abrasion combined with acid etching appears to provide the best conditions for enamel treatment prior to sealant placement.

Acid Etching, Dental↗
PubMed2006

Evaluation of the enamel etching capacity of six contemporary self-etching adhesives.

OBJECTIVES: The purpose of this study was to evaluate the capacity of six contemporary self-etch primers/adhesives to demineralize ground enamel by means of ultrastructural analysis of the etching surface under SEM and by spectroscopic measurement of the percentage of calcium and phosphate ions dissolved. METHODS: Seventy non-carious extracted human third molars were sub-divided into 2 groups of 35 teeth each. The teeth of the first group were ground to expose flat, polished enamel surfaces 3-4mm thick. The samples thus obtained were treated with six self-etch bonding systems and a phosphoric acid gel (control group). The self-etch priming agent was then eliminated and the etched enamel surface observed by SEM. From the teeth of the second group, disc-shaped specimens were made from ground enamel and subjected to application of each of the six self-etchants. Once the etching product had been rinsed off, the rinse solution was analyzed by atomic flame spectroscopy to evaluate the percentage of calcium and phosphate ions dissolved. RESULTS: SEM images show that AdheSE, Adper Prompt L-Pop and Xeno III, despite having a less intensive etching efficacy than phosphoric acid, gave a regular pattern over a considerable surface area and depth. iBond and One-Up Bond F gave less regular demineralization. For Clearfil SE Bond, the demineralization was ineffective. Results of the percentage of mineral loss show that Adper Prompt L-Pop and Xeno III were the most efficient self-etch products. AdheSE, iBond and One-Up Bond F, respectively exhibited decreasing demineralizing capacity. Clearfil SE Bond, however, gave low proportions of calcium and phosphate ions loss and was considered unsatisfactory. CONCLUSION: The action on enamel was not the same for all self-etch systems tested. The etching potential of the self-etch adhesives was lower than that of phosphoric acid but some self-etch systems, particularly those with monomers containing phosphate derivatives, gave results close to those obtained with phosphoric acid.

Acid Etching, Dental↗
PubMed2005

An investigation into the bonding of orthodontic attachments to porcelain.

This study assessed bonding of orthodontic brackets to porcelain teeth using two different surface preparation techniques and comparing two bonding systems, Fuji Ortho L.C. and Transbond. Four groups of 20 porcelain premolar teeth were bonded with metal orthodontic brackets (0.022 inch Minitwin, 3M Unitek) according to the following protocol: Transbond with a phosphoric acid etch (group 1), Transbond with a hydrofluoric acid etch (group 2), Fuji Ortho L.C. with a hydrofluoric acid etch (group 3), and Fuji Ortho L.C. with a phosphoric acid etch (group 4). All groups were bonded with a silane coupling agent. The teeth were debonded with an Instron universal testing machine. Bond strength, site of bond failure and adhesive remnant index (ARI) were recorded for each group. Differences between groups were analysed statistically. The composite resin groups (groups 1 and 2) had the highest mean bond strength values at 7.9 and 9.7 MPa, respectively. The resin-modified glass ionomer cement groups (RMGIC; groups 3 and 4) had the lowest mean bond strength values at 6.3 and 1.8 MPa, respectively. The mean bond strength of group 3 was significantly lower than all other groups (P < 0.0001). The Fuji groups had also significantly (P < 0.001) lower ARI scores than the composite groups (groups 1 and 2). Most samples experienced porcelain surface damage, except group 4. In conclusion, the highest bond strength levels were achieved with a conventional composite resin cement (groups 1 and 2). No significant differences in bond strength were found between the hydrofluoric and phosphoric acid etch technique.

Acid Etching, Dental↗
PubMed1978

The cytochemistry of tartrate-resistant acid phosphatase. Technical considerations.

Cytochemical demonstration of tartrate-resistant acid phosphatase activity is essential for the diagnosis of leukemic reticuloendotheliosis. In order to perform this test correctly and to interpret the results propertly, it is necessary to understand the technical details of the cytochemical methods thoroughly. The method using naphthol--ASBI phosphoric acid--fast garnet GBC is recommended for this purpose, and factors crucial to the cytochemical study, such as fixation, substrate, coupler, pH and temperature of incubation buffer, counterstains, and mounting media are examined and discussed. Conventional methods for acid phosphatase in the presence and absence of L(+) tartaric acid are also critically examined. The naphthol--ASBI phosphoric acid--fast garnet GBC method is sensitive, technically simple and easily reproducible. Its reaction product is highly chromogenic and is most suitable for cytochemical demonstration of acid phosphatase and tartrate-resistant acid phosphatase activity in cytologic preparations. The naphthol--ASBI phosphoric acid--pararosaniline method is highly specific and is best for histochemical demonstration of acid phosphatase and tartrate-resistant acid phosphatase in tissue sections.

Acid Phosphatase↗
PubMed2002

Nail morphology studies as assessments for onychomycosis treatment modalities.

The purpose of this investigation was to study the morphology of the human nail treated with chemical penetration enhancers (CPE), bioadhesives and surface modifiers for assessment of topical treatment modalities for onychomycosis. CPEs, including dimethyl sulfoxide (DMSO) and urea were applied to human nail samples. Additional samples were treated with surface modifiers, tartaric acid (TTA) and phosphoric acid gel (PA). Other nail specimens were subjected to the bioadhesive polymers Carbopol 971P and Klucel MF. Atomic force microscopy (AFM), scanning electron microscopy (SEM) and polarized light microscopy (PLM) were utilized to visualize nail morphology and topographical changes of the human nail samples subjected to the various chemical agents. AFM, SEM and PLM micrographs revealed changes in topography to the dorsal layer when CPEs and surface modifiers were applied. Roughness scores as determined by NANOSCOPE IIIA software indicated a 2-fold increase when the dorsal nail layer was subjected to PA versus the control (147.8 vs. 85.0 nm, respectively). In contrast, when carbomer 971P was applied to the dorsal surface, roughness scores decreased significantly (44.6 vs. 85.0 nm, respectively). AFM, SEM and PLM studies of the human nail subjected to various chemical agents may be useful in the design and formulation of novel drug delivery systems for the topical treatment of onychomycosis. The AFM studies offer both a qualitative and quantitative assessment for nail treatment opportunities.

Analysis of Variance↗
PubMed2003

SEM and TEM analysis of water degradation of human dentinal collagen.

Recently several long-term studies have reported evidence of the hydrolytic degradation of collagen fibrils based on fractured surface observations after bond testing. Those studies suggested that one cause of the decline in the bond strength was the degradation of the collagen fibrils within the bonds. However, one concern has been raised that the dentinal collagen fibrils may be stable in water that does not contain oral bacteria or enzymes. Therefore, the present study aimed to clarify the micromorphological change in naked collagen fibrils after 500 days of water storage. To prepare exposed collagen fibrils, sectioned and polished human dentin surfaces were acid conditioned for 15 s with the use of two commercially available acid conditioners: All-Etch (10% phosphoric acid) and Uni-Etch (32% phosphoric acid) (Bisco, Inc.). Those specimens were stored in distilled water at 37 degrees C for 1 day (control) for 500 days. After the storage periods, the samples were examined with the use of SEM and TEM. Under SEM and TEM examination, micromorphological alterations (disarrangement of collagen web, widening the interfibrillar space, and the thinning diameter of collagen fibrils) were found in the specimens after 500 days in water.

Acid Etching, Dental↗
PubMedDate not supplied

Effect of chemical and microbial amendments on ammonia volatilization from composting poultry litter.

Research has shown that aluminum sulfate (alum) and phosphoric acid greatly reduce ammonia (NH3) volatilization from poultry litter; however, no studies have yet reported the effects of these amendments on field-scale composting of poultry litter. The objectives of this study were to (i) evaluate NH3 volatilization from composting litter by measuring both NH3 volatilization and changes in total nitrogen (N) in the litter and (ii) evaluate potential methods of reducing NH3 losses from composting poultry litter. Poultry litter was composted for 68 d the first year and 92 d the second year. Eleven treatments were screened in Year 1, which included an unamended control, a microbial mixture, a microbial mixture with 5% alum incorporated into the litter, 5 and 10% alum rates either surface-applied or incorporated, and 1 and 2% phosphoric acid rates either surface-applied or incorporated. Treatments in Year 2 included an unamended control, a microbial mixture, alum (7% by fresh wt.), and phosphoric acid (1.5% by fresh wt.). Alum and phosphoric acid reduced NH3 volatilization from composting poultry litter by as much as 76 and 54%, respectively. The highest NH3 emission rates were from microbial treatments each year. Compost treated with chemical amendments retained more initial N than all other treatments. Due to the cost and N loss associated with composting poultry litter, composting is not economical from an agronomic perspective compared with the use of fresh poultry litter.

Air Pollutants↗
PubMed1997

Preparation of an effective light-cured bonding agent for orthodontic application.

OBJECTIVE: The purpose of this study was to prepare a light-cured adhesive applicable for orthodontics by mixing monomers and a polymerized reactive organic composite filler (prepolymerized trimethylolpropane trimethacrylate-filler, TMPT-filler). METHODS: The monomer component was a mixture of 3.0 wt% 2-hydroxy-3-(2-naphthoxy)propyl methacrylate (HNPM) in triethylene glycol dimethacrylate. This was applied to extracted bovine tooth enamel after acid etching with 65 wt% phosphoric acid for 30 s. After 24 h in 37 degrees C water, the tensile bond strength was measured, and the data were analyzed with Duncan's new multiple range test (p < 0.01 or 0.05). RESULTS: The tensile bonding strength to enamel etched with 65 wt% phosphoric acid was 13.1 +/- 0.5 MPa, and the thermal stability of the bond was excellent. SEM examination of the cross-sectioned specimens modified with HCl demineralization showed that when the diffusion time prior to light irradiation was only 1 min, a well-developed resin honeycomb-like structure was created in the enamel surface in the formulation containing HNPM. SIGNIFICANCE: Monomer impregnation beyond the etched enamel surface was important for resin-enamel bonding, increasing bonding strength and thermal stability. HNPM was effective in enhancing monomer diffusion and impregnation of the etched enamel surface.

Acrylates↗
PubMed2005

Microtensile adhesion of sealants to intact enamel.

UNLABELLED: Contamination of etched enamel with saliva has been shown to result in sealant failure. Hydrophilic adhesives improve retention of sealants when enamel is contaminated. OBJECTIVE: The objective of the present study was to characterize the adhesion of two sealants to unprepared enamel etched with phosphoric acid or conditioned with the all-in-one, self-etch adhesive Adper Prompt L-Pop. METHODS: The two proximal enamel surfaces of 16 sound molars were assigned to four conditioning regimens: (1) 35% phosphoric acid for 15 s; (2) Adper Prompt L-Pop, one layer light-cured prior to sealant placement; (3) Adper Prompt L-Pop, two layers light-cured prior to sealant placement; and (4) Adper Prompt L-Pop, one layer co-cured with sealant. One of two sealants, i.e. Clinpro or Delton DDS, was applied, light-cured, followed by a composite build-up to provide support for microtensile bond testing. RESULTS: The highest mean bond strengths were obtained when Adper Prompt L-Pop was applied in two layers and light-cured prior to the insertion of Clinpro Sealant. Co-cure of Adper Prompt L-Pop with either sealant resulted in bond strengths which were not significantly different from those of the phosphoric acid control. The use of Adper Prompt L-Pop in one layer cured prior to sealant placement resulted in statistically lower bond strengths than any other application technique regardless of the sealant used. Clinpro Sealant resulted in statistically higher bond strengths than Delton DDS Sealant. CONCLUSIONS: Application of one layer of Adper Prompt L-Pop co-cured with the sealant resulted in bond strengths similar to those obtained with phosphoric acid etching.

Acid Etching, Dental↗
PubMed2002

Effect of using self-etching primer for bonding orthodontic brackets.

Questions over the use of self-etching primers with composite resin adhesives in the bonding of orthodontic brackets remain unsolved. In addition, there are no previous reports on the efficacy of self-etching primers with resin-modified glass ionomer cements for bonding orthodontic brackets in orthodontic dentistry. The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of four protocols: (1) a composite resin adhesive used with 40% phosphoric acid, (2) the same composite resin used with Megabond self-etching primer, (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. The appearance of the tooth surfaces after acid etching or priming was observed with a field-emission scanning electron microscope (FE-SEM). When used with resin-modified glass ionomer cement, Megabond self-etching primer gave no significantly different shear bond strength compared with polyacrylic acid etching. But when used with composite resin adhesive, Megabond self-etching primer gave significantly lower shear bond strength than phosphoric acid etching. However, the shear bond strength of orthodontic brackets bonded with composite resin adhesive after Megabond priming was almost the same as that of brackets bonded with resin-modified glass ionomer cement after polyacrylic acid etching. FE-SEM observation revealed that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching. Megabond self-etching primer may be a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement for minimizing the amount of enamel loss.

Acid Etching, Dental↗
PubMed1984

Clinical trials with crystal growth conditioning as an alternative to acid-etch enamel pretreatment.

It has been claimed that different ion solutions containing sulfate induce crystal growth and might be a better alternative than conventional acid etching for enamel pretreatment in bracket bonding. It should thus combine optimal bond strength with easy and quick debonding. Two clinical experiments were performed to test this hypothesis. The first experiment dealt with the debonding procedure. Following conditioning with dilute sulfuric acid which contained sodium sulfate (to be termed solution A) on one side of the mouth and etching with 37% phosphoric acid on the other, brackets were bonded on the maxillary and mandibular incisors of twenty dental nurse students. Debracketing and a subsequent cleanup procedure were performed after 2 days. The mode of loosening was mainly between the enamel surface and adhesive on the crystal-growth-conditioned teeth and between the bracket mesh and adhesive on the teeth etched with phosphoric acid. This difference in mode of loosening was statistically significant (P less than 0.001). In the second experiment, which dealt with the clinical bond strength, 250 brackets were bonded in forty patients. One side served as a control and was conventionally acid etched. On the experimental side conditioning was done with solution A in thirty patients. In ten patients, 10% phosphoric acid was added to the dilute sulfuric acid used (to be termed solution B). Failure rates and modes of failure were recorded for a 6-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1996

Influence of enamel conditioning on bond strength of resin-modified glass ionomer restorative materials and polyacid-modified composites.

This study evaluated enamel bond strength of restorative materials containing both glass ionomer and composite components. Three resin-modified glass ionomer restorative materials (Fuji II LC, Vitremer, Photac-Fil), three polyacid-modified composites (VariGlass VLC, Dyract, Ionosit Fil), a hybrid composite (blend-a-lux) and a chemical-cured glass-ionomer cement (ChemFil Superior) were tested for enamel tensile bond strength with and without conditioning of the tooth surfaces. Tensile bond strength was determined for five specimens each of conditioned and unconditioned bovine teeth. Specimen conditioning was performed as recommended by the manufacturers. The tensile bond strength was tested with a universal testing machine. Except for the enamel bond strength of ChemFil Superior, all materials showed greater adhesion to conditioned tooth surfaces than to unconditioned specimens. Enamel bond strengths of the polyacid-modified composites applied after a phosphoric acid etching technique (Ionosit Fit, Dyract, VariGlass) were greater compared with the materials applied after surface conditioning with polyacrylic acid-containing agents. No significant difference was observed between the hybrid composite and the tested materials attached with the phosphoric acid etching technique. To improve adhesion of the tested materials to enamel, following the manufacturer's instructions about tooth surface conditioning is recommended. Superior bond strength to enamel was obtained for polyacid-modified composites, which are attached with the phosphoric acid etching technique and thereby resemble the adhesion patterns of composites.

Acid Etching, Dental↗
PubMedDate not supplied

[Inhibition of yeast pyruvate decarboxylase by alkyl phosphates].

It is found that yeast pyruvate decarboxylase is inhibited by alkyl phosphates. Inhibition is competitive with respect to a substrate. The inhibition constants with n-butyl and n-heptyl esters of phosphoric acid are the values of the same order of magnitude. With an increase in the length of the alkyl phosphates hydrocarbon chain from 7 to 10 carbon atoms inhibition constants change drastically. For n-heptyl phosphate and n-decyl phosphate values KI are equal to 1.6 x 10(-4) M and 1.7 x 10(-6) M, respectively. A further increase in the number of carbon atoms in the alkyl substituent of phosphoric acid ester induces no reduction of the inhibition constant. Multiple-inhibitor experiments of pyruvate decarboxylase show that inorganic phosphate and n-decyl ester of phosphoric acid are mutually exclusive. It is suggested that the inhibition mechanism with alkyl phosphates includes the competition of the phosphoric acid residue with alpha-ketocarboxyl group of pyruvate as well as the interaction between a hydrocarbon radical and hydrophobic parts on the enzyme surface, one of them being outside the substrate binding site.

Alkylation↗
PubMed1989

The effect of sealing white spot lesions on lesion progression in vitro.

The resistance of white spot lesions to acid demineralization when etched with phosphoric acid and sealed with a resin material was studied. Artificially created white spot lesions were sealed and re-exposed to an artificial caries medium along with unprotected white spot lesions. Examination with polarized light microscopy revealed continued progression of the unprotected white spot lesions, whereas no lesion progression was evident under the resin sealant. New lesions formed on unprotected sound enamel adjacent to the margin of the resin sealant over sound enamel tangent to the white spot lesions. The sealed sound enamel adjacent to the white spot lesions did not undergo demineralization indicating protection by the resin tags. Sealing white spot lesions following etching with a 37% phosphoric acid may be beneficial in inhibiting lesion progression.

Acid Etching, Dental↗
PubMed2006

Scanning electron microscopy evaluation of the bonding mechanism of a self-etching primer on enamel.

The aim of this study was to analyze the effect of a self-etching primer (Transbond Plus SEP, 3M Unitek, Monrovia, Calif), developed for orthodontic use, in the regularity and depth of adhesive infiltration in the enamel of human permanent teeth and to compare it with phosphoric acid using scanning electron microscopy (SEM). Thirty premolars were divided in two groups of 15 each: group 1(control)-phosphoric acid + Transbond XT Primer (3M Unitek) and group 2- Transbond Plus SEP. Transbond XT Adhesive Paste (3M Unitek) was used in both groups for bracket bonding. All products were used according to the manufacturer's instructions. Dental fragments were decalcified, and for micromorphologic observation of the adhesive penetration in enamel, the resin replicas, remnant at the base of the brackets, were covered with a thin gold layer and examined by SEM. Three calibrated examiners evaluated the photomicrographs and gave scores from 0 = without penetration to 2 = deep penetration. The Mann Whitney U-test (P < .0001) showed a statistical difference between the two groups. The results demonstrated that the SEP was more conservative and produced a smaller amount of demineralization and less penetration of adhesive in the enamel surfaces when compared with the conventional phosphoric acid system.

Acid Etching, Dental↗
PubMed1996

Apparent heterogeneity of recombinant interferon gamma receptors produced in prokaryotic and eukaryotic expression systems.

Recombinant proteins show several types of heterogeneity and post-translational modifications which are usually related to their production system. The apparent heterogeneity of recombinant interferon gamma receptors and interferon gamma receptor-immunoglobulin G fusion proteins expressed in Escherichia coli, baculovirus-infected insect cells and Chinese hamster ovary cells have been studied. In general, all proteins tested showed some type of heterogeneity which was detectable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The E. coli-derived receptor included non-native conformations involving mis-paired or non-formed disulfides. This type of heterogeneity affected the biological activity of the protein. In addition, the prokaryotic protein had trapped phosphoric acid during downstream processing. The phosphoric acid entrapment did not affect ligand binding capacity. The eukaryotic proteins showed heterogeneity because of the unequal cleavage of the signal peptide and because of differences in glycosylation. The latter types of heterogeneity did not affect activity. Glycosylation-related heterogeneity was partially derived from the unequal utilization of the potential N-glycosylation sites and differently affected the apparent molecular masses and migrations of the proteins on polyacrylamide gels. The results may be useful in characterization studies of recombinant proteins.

Amino Acid Sequence↗