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PubMed2002

Mechanisms involved in the resistance of Enterococcus faecalis to calcium hydroxide.

AIM: This study sought to clarify the mechanisms that enable E. faecalis to survive the high pH of calcium hydroxide. METHODOLOGY: E. faecalis strain JH2-2 was exposed to sublethal concentrations of calcium hydroxide, with and without various pretreatments. Blocking agents were added to determine the role of stress-induced protein synthesis and the cell wall-associated proton pump. RESULTS: E. faecalis was resistant to calcium hydroxide at a pH of 11.1, but not pH 11.5. Pre-treatment with calcium hydroxide pH 10.3 induced no tolerance to further exposure at pH 11.5. No difference in cell survival was observed when protein synthesis was blocked during stress induction, however, addition of a proton pump inhibitor resulted in a dramatic reduction of cell viability of E. faecalis in calcium hydroxide. CONCLUSIONS: Survival of E. faecalis in calcium hydroxide appears to be unrelated to stress induced protein synthesis, but a functioning proton pump is critical for survival of E. faecalis at high pH.

Calcium Hydroxide↗
PubMed1991

Aluminum accumulation during treatment with aluminum hydroxide and dialysis in children and young adults with chronic renal disease.

BACKGROUND: The control of hyperphosphatemia is a major clinical problem in patients with chronic renal failure receiving regular dialysis treatment. Despite continuing concern about aluminum toxicity, aluminum-containing antacids are still used in many of these patients as phosphate-binding agents. Although maximal acceptable doses of aluminum hydroxide have been recommended, the safety and efficacy of these guidelines have not been evaluated. METHODS: Seventeen children and young adults (mean [+/- SD] age, 14.1 +/- 3.7 years) undergoing regular peritoneal dialysis were randomly assigned to treatment with either aluminum hydroxide (n = 7; maximal dose, 30 mg per kilogram of body weight per day) or calcium carbonate (n = 10; dose range, 2.5 to 12 g per day, according to serum phosphorus levels). Aluminum retention was assessed by serial measurements of plasma aluminum, deferoxamine-infusion tests, and measurements of bone aluminum content during a mean (+/- SD) follow-up of 13 +/- 2 months. The evolution of bone disease was also evaluated. RESULTS: Plasma aluminum levels and the increment in plasma aluminum after infusion of deferoxamine increased from base-line values in the patients treated with aluminum hydroxide, and aluminum-related bone disease developed in one patient. Serum phosphorus levels remained higher and serum calcium levels lower in the patients receiving aluminum hydroxide than in those receiving calcium carbonate. The skeletal lesions of secondary hyperparathyroidism improved in 7 of 10 patients receiving calcium carbonate but persisted or progressed in 6 of 7 patients given aluminum hydroxide (P less than 0.025). CONCLUSIONS: Aluminum hydroxide is less effective than calcium carbonate as a phosphate-binding agent for the control of hyperphosphatemia and is associated with aluminum retention in children and young adults with chronic renal failure who are receiving dialysis therapy.

Adolescent↗
PubMed2002

Calcium hydroxide as a temporary filling of the post space in root-filled teeth.

OBJECTIVE: The purpose of this in vitro study was to evaluate whether the saline content of the calcium hydroxide paste used as a temporary filling in the post space of root-filled teeth would significantly affect the seal of the apical root fillings (gutta-percha and zinc oxide-eugenol based sealer) during a period of 1 month. STUDY DESIGN: Eighty extracted single-rooted and multirooted teeth were cut at the cemento-enamel junction. They were endodontically instrumented and filled with zinc oxide-eugenol based sealer and gutta-percha. A post space was immediately prepared on 70 teeth. The experimental teeth were then randomly divided into 4 groups: A, post space filled with calcium hydroxide paste (30 teeth); B, post space without calcium hydroxide paste (30 teeth); C, negative controls (10 teeth); and D, positive controls (10 teeth). The teeth were stored in a humidified chamber at room temperature for a month. After storage, the calcium hydroxide paste in the post spaces in group A was removed. All roots were coated with 2 layers of nail varnish and sticky wax externally, placed in a glass bottle containing methylene blue, and subjected to a vacuum for 15 minutes. The teeth were then stored for another week, sectioned in half longitudinally, and examined for dye penetration. The mean and standard deviation of dye penetrations for each group were calculated, and a Student t test was used to determine the statistical difference between the groups. RESULTS: There was no significant difference in the coronal dye leakage of the apical root fillings between the post spaces filled with the calcium hydroxide paste and those without during a period of 1 month. CONCLUSIONS: The saline content in the calcium hydroxide paste placed in the post space as a temporary filling did not significantly affect the seal of the apical root fillings during a period of 1 month by using a dye leakage study.

Calcium Hydroxide↗
PubMed1989

Inhibitory effect of magnesium hydroxide on methylazoxymethanol acetate-induced large bowel carcinogenesis in male F344 rats.

The effect of dietary magnesium hydroxide on colon carcinogenesis induced by methylazoxymethanol (MAM) acetate was examined in male F344 rats. MAM acetate was administered by i.p. injection to rats at 25 mg/kg body wt once per week for 3 weeks. Starting 2 weeks after the final MAM acetate exposure, the diet containing 500 or 1000 p.p.m. magnesium hydroxide was fed for 227 days. In the groups receiving magnesium hydroxide and MAM acetate, the incidence of colon neoplasms was decreased when compared with that in the group given MAM acetate alone. The inhibitory effect of dietary magnesium hydroxide on MAM acetate-induced colon carcinogenesis was greater at the lower dose than that at the higher dose of magnesium hydroxide in the diet. Neoplasms in other organs were rare and were not affected by the dietary magnesium hydroxide.

Animals↗
PubMed1994

The inhibitory effect of magnesium hydroxide on the bile acid-induced cell proliferation of colon epithelium in rats with comparison to the action of calcium lactate.

The modulating effects of magnesium hydroxide and calcium lactate on the cholic acid-induced hyperproliferation of cells in rat colon epithelium were investigated. Rats were divided into six groups (10 rats/group) and fed the following diets for 8 weeks: 0.25% cholic acid alone (group 1), cholic acid plus 0.2% magnesium hydroxide (group 2), cholic acid plus 1.18% calcium in the form of calcium lactate (group 3), calcium lactate alone (group 4), magnesium hydroxide alone (group 5) and the basal diet alone (group 6). At the end of the experiment, all rats were killed for the immunocytochemical examination of 5-bromo-2'-deoxyuridine (BrdU) incorporation in the cell nuclei of colonic epithelium. Magnesium hydroxide reduced the cholic acid-induced BrdU incorporation by 33% at the distal part and 40% at the proximal part. Calcium lactate also reduced the BrdU incorporation by 48% and 51% respectively. Exposure of magnesium hydroxide or calcium lactate alone had no influence on BrdU incorporation. The results suggest that magnesium hydroxide might exert anti-carcinogenic effects as does calcium by reducing increased cell proliferation of colonic epithelium induced by toxic effects of bile acids, which are regarded as colon tumor promoters or cocarcinogens.

Animals↗
PubMed2001

Calcium concentration and pH of the periapical environment after applying calcium hydroxide into root canals in vitro.

The purpose of the present study was to determine both calcium concentration and pH in the periapical region after application of 1 of 4 different calcium hydroxide preparations into experimental root canals. Fifty root canal models were divided into five groups: group 1--calcium hydroxide was mixed with distilled water at a powder/water weight ratio of 38%; group 2--calcium hydroxide was mixed with distilled water at 44%; group 3--calcium hydroxide was mixed with distilled water at 50%; group 4--calcium hydroxide powder only was used; and group 5-the control group, in which nothing was applied to the canals. All samples were immersed in distilled water maintained at 37 degrees C. Calcium concentration and pH of the distilled water were measured after 3 days, 7 days, and then at weekly intervals up to 15 wk, during which time the storage medium was renewed after each measurement. Calcium concentration and the change in pH of the distilled water were statistically quicker and greater in groups 1 to 3 (mixture groups) than group 4 (powder only) (p < 0.05). The highest calcium concentration (peak Ca2+ release) was observed after 3 days for the mixture groups, whereas that for the powder only group was found at 7 days. Peak pH change was found after 14 days for the mixture groups, whereas that for the powder only group was found at 49 days. After peaking, all groups showed a decline of the pH over time. These results suggest that the time required for optimum intracanal activity when using calcium hydroxide mixtures is at least 2 wk.

Analysis of Variance↗
PubMed2001

Two methods to evaluate the antimicrobial action of calcium hydroxide paste.

The objective of this study was to analyze two methods for determining the antimicrobial effectiveness of (i) calcium hydroxide plus saline, (ii) calcium hydroxide plus polyethylene glycol, and (iii) calcium hydroxide plus camphorated paramonochlorophenol. Four microorganisms (Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), and Bacillus subtilis (ATCC 6633)), one yeast (Candida albicans (ICB/USP-562)), and one mixture of these organisms were used. The strains were inoculated in Brain Heart Infusion (BHI) and incubated at 37 degrees C for 24 h. Two methods, the direct exposure test and the agar diffusion test were used to evaluate antimicrobial effects. For the direct exposure test (DET) 288 paper points were contaminated with the standard microbial suspensions and exposed to the intracanal dressings for 1, 24, 48, and 72 h. The points were immersed in Letheen Broth, followed by incubation at 37 degrees C for 48 h. An inoculum of 0.1 ml obtained from Letheen Broth was then transferred to 7 ml of BHI under identical incubation conditions, and microbial growth was evaluated. Pastes showed activity between 1 and 72 h, depending on the microorganism/mixture tested. For the agar diffusion test 36 Petri plates with 20 ml of BHI agar were inoculated with 0.1 ml of the same microbial suspension used for the DET, using sterile swabs that were spread on the medium. Five cavities were made in each of two agar plates (total = 10) and completely filled with one of the calcium hydroxide pastes. The plates were preincubated for 1 h at environmental temperature and then incubated at 37 degrees C for 24 to 48 h. The inhibition zone around each well was recorded in millimeters, and the results were submitted to ANOVA and Tukey test (alpha = 0.05). All intracanal dressings induced inhibition zones (range 5.0-10.0 mm). Data obtained showed that both the DET and agar diffusion test are useful in establishing the calcium hydroxide antimicrobial spectrum, thus improving infection control protocols. The direct exposure method is independent of other variables and is a practical laboratory procedure. A complete antimicrobial effect was observed after 48 h on indicator microorganisms, in both tests, irrespective of the calcium hydroxide paste vehicle.

Analysis of Variance↗
PubMed1991

The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac.

1. The effect of magnesium hydroxide on the oral absorption of ibuprofen, ketoprofen and diclofenac was investigated in two randomized cross-over studies, both consisting of two phases. 2. Single doses of magnesium hydroxide (850 mg) or of water (150 ml) only were given to six healthy volunteers immediately after the ingestion of ibuprofen (400 mg, Study 1), ketoprofen (50 mg, Study 2) or diclofenac (50 mg, Study 2). Plasma drug concentrations were measured up to 24 h. 3. Magnesium hydroxide increased the area under the plasma ibuprofen concentration-time curve between 0 and 1 h by 65% (P less than 0.05) and the peak concentration of ibuprofen in plasma by 31% (P less than 0.01). The time to peak was shortened by about 0.5 h. The extent of bioavailability of ibuprofen was not increased by magnesium hydroxide. 4. Neither the rate nor the extent of absorption of ketoprofen or diclofenac was changed significantly by magnesium hydroxide. 5. When rapid onset of the analgesic effect of ibuprofen is required, concomitant ingestion of an antacid, which contains magnesium hydroxide without aluminium, is recommended.

Adult↗
PubMed2004

In vitro antibacterial effect of calcium hydroxide combined with chlorhexidine or iodine potassium iodide on Enterococcus faecalis.

Several studies have shown a higher success rate of root canal therapy when the canal is free from bacteria at the time of obturation. Treatment strategies that are designed to eliminate this microflora should include agents that can effectively disinfect the root canal. Enterococcus faecalis is often associated with persistent endodontic infections. While in vivo studies have indicated calcium hydroxide to be the most effective all-purpose intracanal medicament, iodine potassium iodide (IKI) and chlorhexidine (CHX) may be able to kill calcium hydroxide-resistant bacteria. Supplementing the antibacterial activity of calcium hydroxide with IPI or CHX preparations was studied in bovine dentine blocks. While calcium hydroxide was unable to kill E. faecalis in the dentine, calcium hydroxide combined with IKI or CHX effectively disinfected the dentine. The addition of CHX or IKI did not affect the alkalinity of the calcium hydroxide suspensions. It may be assumed that combinations also have the potential to be used as long-term medication. Cytotoxicity tests using the neutral red method indicated that the combinations were no more toxic than their pure components.

Animals↗
PubMedDate not supplied

Lack of maternal and developmental toxicity in mice given high doses of aluminium hydroxide and ascorbic acid during gestation.

The present study was conducted to assess if the concurrent ingestion of high doses of aluminium hydroxide and ascorbic acid might result in maternal and developmental toxicity in mice. Three groups of pregnant Swiss mice were given by gavage daily doses of aluminium hydroxide (300 mg/kg), ascorbic acid (85 mg/kg), or aluminium hydroxide (300 mg/kg) concurrent with ascorbic acid 85 (mg/kg) on gestational days 6-15. A fourth group of animals received distilled water and served as control group. Dams were killed on gestation day 18 and foetuses were examined for external, internal, and skeletal abnormalities. The reproductive data did not show embryotoxic or foetotoxic effects in any group. No gross, internal, or skeletal malformations or variations related to the different treatments were found. There were no significant differences between control and treated groups on the aluminium levels in maternal liver and bone as well as in whole body foetuses, whereas aluminium concentrations were significantly higher in placenta and kidney of dams receiving aluminium hydroxide and aluminium hydroxide plus ascorbic acid than in those from the control group. Although in this study aluminium hydroxide was given at doses higher than those usually consumed by pregnant women, no signs of maternal or developmental toxicity were observed when the compound was given alone or concurrently with high doses of ascorbic acid.

Aluminum Hydroxide↗
PubMed1997

A histological and quantitative histomorphometric study of apexification of nonvital permanent incisors of vervet monkeys after repeated root filling with a calcium hydroxide paste.

The purpose of this study was to compare the effect of a monthly refilling of the root canals with calcium hydroxide paste with a single packing or replacement of the paste at 3 months on the apexification of nonvital maxillary incisors of vervet monkeys. Forty-eight maxillary incisors from 12 monkeys were used following radiographic determination that root development was incomplete. The pulps were extirpated under general anesthesia and the root canals filed and cleaned. The root canals were filled with a commercial calcium hydroxide paste, Calxyl, and a temporary cavity filling placed. Twelve teeth were left without further treatment. The calcium hydroxide paste was replaced in 12 teeth after a 3-month interval, and in the remaining 24 teeth the calcium hydroxide root filling was replaced five times at monthly intervals. The monkeys were killed after 6 months, and blocks of the teeth and surrounding tissues were embedded, decalcified and 6 microns serial sections prepared and stained. The sections were studied histologically to evaluate 11 parameters. Significant differences were found in the amount of calcium hydroxide at the apices, the presence of new cementum on the roots and the degree of inflammation, all of which were better in the monthly refill group. Histomorphometric measurements to evaluate the obturation of the open apices and the volume of new primary osteocementum showed no significant difference between the three groups. It was suggested that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months, for at least 6 months.

Analysis of Variance↗
PubMed2007

The effect of calcium hydroxide root filling on dentin fracture strength.

This in vitro study measured the effect of calcium hydroxide root filling on the microtensile fracture strength (MTFS) of teeth. A total of 40 extracted human disease-free permanent maxillary incisors were hand and rotary instrumented and vertically compacted with United States Pharmacopeia (USP) calcium hydroxide. The teeth were stored in a moist environment for 7, 28, and 84 days. As a control group, 10 teeth were vertically compacted with gutta percha and sealer. The MTFS of the teeth was measured (Mpa) using an Instron machine. Data were assessed statistically using an unpaired t-test (P value). The intracanal placement of calcium hydroxide weakened the MTFS of teeth by 13.9 Mpa per 77 days: an average of 0.157 MPa day-1. Between 7 and 84 days, the MTFS of the dentin was reduced by 43.9%. This difference was statistically significant (P < 0.05). A statistical difference (P < 0.05) was observed between the mean MTFS of the calcium hydroxide-filled dentin between 7 days (45.7 MPa) and 28 days (35.6 MPa) and also between 7 and 84 days (31.8 MPa). There was also a significant difference (P < 0.05) between the MTFS of the calcium hydroxide-filled dentin after 84 days (31.8 MPa) and the gutta percha-filled dentin (41.3 MPa) when used as a control root filling material. The weakening of the dentin by 23-43.9% following root canal filling with calcium hydroxide provides compelling evidence to re-evaluate the daily usage of this material in endodontic therapy.

Calcium Hydroxide↗
PubMed2001

The Common vaccine adjuvant aluminum hydroxide up-regulates accessory properties of human monocytes via an interleukin-4-dependent mechanism.

Aluminum adjuvants are widely used in human vaccines based on their ability to enhance antibody production. However, the mechanisms underlying these effects remain unknown. In the present study we assessed the direct in vitro effect of aluminum hydroxide on human peripheral blood monocytes, specifically with regard to its impact on the phenotype and functional properties of this cell population. Our results revealed significant changes in the accessory properties of monocytes following short-term exposure of cultured cells to aluminum hydroxide. Thus, flow cytometry analyses showed an increase in the expression of major histocompatibility complex (MHC) class II, CD40, CD54, CD58, CD83, and CD86 molecules on the monocytes. In addition, many cells in the cultures containing aluminum hydroxide acquired typical dendritic morphology. Increased synthesis of interleukin-4 (IL-4) mRNA, but not gamma interferon mRNA, was also noted after exposure to aluminum hydroxide. The increase in cell surface expression of MHC class II did not occur in the presence of neutralizing IL-4 antibody or in cultures of highly purified monocytes or CD4-depleted mononuclear cells. Our findings suggest that aluminum hydroxide directly stimulates monocytes to produce proinflammatory cytokines activating T cells. Activated Th2 cells release IL-4, which in turn can induce an increase in the expression of MHC class II molecules on monocytes. The increase in the expression of antigen-presenting and costimulatory molecules leads to enhanced accessory functions of monocytes. These properties of aluminum hydroxide observed in vitro may explain its potent in vivo adjuvant effect.

Adjuvants, Immunologic↗
PubMed1990

Effect of aluminum hydroxide gel on quinidine gluconate absorption.

The effect of aluminum hydroxide gel on quinidine gluconate bioavailability was studied in eight nonsmoking healthy male volunteers. Subjects were randomized to receive quinidine gluconate 648 mg with and without 30 mL of aluminum hydroxide gel. The mean area under the concentration-time curve (AUC) (23.11 +/- 5.21 mg.h/L), time to reach maximum concentration (tmax) (3.13 +/- 0.64 h), maximum serum concentration (1.44 +/- 0.41 mg/L), and elimination rate constant (0.069 +/- 0.010-h) observed during the control phase of the trial did not differ significantly (p greater than 0.05) from values obtained during the coadministration of aluminum hydroxide with quinidine gluconate (23.91 +/- 4.48 mg.h/L, 4.13 +/- 2.12 h, 1.53 +/- 0.34 mg/L, and 0.077 +/- 0.013-h, respectively). There was considerable individual variation in AUC with one subject demonstrating an increase of 35 percent and one subject demonstrating a decrease of 18 percent. There was a trend toward aluminum hydroxide delaying tmax with only one subject experiencing an earlier tmax with the coadministration of aluminum hydroxide. The results of this single-dose trial suggest that, although statistically the concurrent administration of aluminum hydroxide gel with quinidine gluconate does not significantly alter the extent of quinidine absorption, clinically significant individual variations may occasionally occur.

Adult↗
PubMedDate not supplied

Indirect pulp treatment: in vivo outcomes of an adhesive resin system vs calcium hydroxide for protection of the dentin-pulp complex.

PURPOSE: The purpose of this prospective and randomized in vivo study was to compare the clinical and radiographic outcomes of an adhesive resin system vs a calcium hydroxide liner for protection of the dentin-pulp complex of primary molars treated with indirect pulp treatment. METHODS: Forty-eight primary molars with deep occlusal caries, but without preoperative signs and symptoms of irreversible pulpitis, received indirect pulp treatment and were restored with a composite resin (Z100). The teeth were randomly divided into 2 groups according to the material used for protection of the dentin-pulp complex: (1) adhesive resin system (Scotchbond MultiPurpose); and (2) calcium hydroxide liner (Dycal). These teeth were evaluated clinically and radiographicaly for 2 years. RESULTS: After 2 years, 83% (19/23) of the teeth treated with calcium hydroxide and 96% (24/25) of teeth treated with only the adhesive resin system presented a successful outcome, as determined by clinical and radiographic examination. Interradicular and/or periapical lesions were the most predominant signs of treatment failure, since 3 out of 23 teeth treated with calcium hydroxide and 1 out of 25 teeth treated with only adhesive resin presented this outcome. One tooth treated with the calcium hydroxide liner was diagnosed with internal root resorption at the 18-month examination. Of the 5 teeth diagnosed from radiographs as a failure of the indirect pulp treatment, none presented clinical signs/symptoms of pulpitis or necrosis such as the presence of fistula, enhanced tooth mobility, or pain. CONCLUSIONS: This study demonstrates that protection of the dentin-pulp complex of primary molars with an adhesive resin system results in similar clinical and radiographic 2-year outcomes as compared to calcium hydroxide when indirect pulp treatment is performed in Class I composite restorations.

Calcium Hydroxide↗
PubMed2005

The influence of some dentin primers on calcium hydroxide lining cement.

UNLABELLED: Dentin primer is applied as a routine procedure prior to bonding to improve the sealing properties of direct polymerizing resins. Some primers contain acetone or alcohol that may affect the properties of calcium hydroxide liner which is placed as a direct or indirect pulp cap. If calcium hydroxide is softened or smeared over the cavity walls, the bonding will be impaired. Therefore, if this occurs, the cement must be removed, the walls must be cleansed, and the procedure must be repeated with careful application of dentin primer. OBJECTIVE: The purpose of this study was to determine the wear and compressive strength of a calcium hydroxide liner after exposure to different kinds of dentin primers for different periods of time. METHODS: The calcium hydroxide used in this study was Dycal. It was mixed according to the manufacturer's instructions and placed in plastic rings of 0.5 mm x 5 mm and allowed to set at 37 degrees C for 15 min under 500 gm load. To determine erosion, the height for each sample before and after application of primers was recorded using a Digital Height Measuring Instrument "Digmar" 817. Compressive strength specimens were also prepared. RESULTS: Calcium hydroxide treated with Optibond (alcohol based) or Syntac (acetone based) for 1 min or 5 min had the highest erosion values and the lowest compressive strength values. Gluma CPs (water based primer) had the least effect on calcium hydroxide values.

Analysis of Variance↗
PubMed1994

Pulp response to a novel adhesive calcium hydroxide based cement.

This study compares pulp responses to 3 formulations of calcium hydroxide, namely: a) An experimental adhesive calcium hydroxide cement containing polyacrylic acid, b) Dycal (L.D> Caulk Co, Milford, Delaware) Batch Nos 176970/176990, c) "Analar" calcium hydroxide mixed with sterile distilled water. After 28 days dentine bridges were present in 77% of teeth capped with the test material, 64% of teeth treated with Dycal and in 62% of teeth capped with calcium hydroxide and water. Inflammatory infiltrates were observed in a number of teeth remote from the bridges. Bacteria were detected in these specimens. Exposed rat molar pulp responses to an experimental adhesive calcium hydroxide cement were similar to to those observed with 2 other calcium hydroxide formulations.

Animals↗
PubMedDate not supplied

Role of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant.

The fact that both aluminum hydroxide adjuvant and proteins have a pH dependent surface charge means that electrostatic forces play a role in the adsorption of proteins by aluminum hydroxide adjuvant during the preparation of vaccines. The objective of this study was to examine the contribution of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant. Since the surface charge characteristics of aluminum hydroxide adjuvant can be modified by the adsorption of phosphate anion, a series of aluminum hydroxide adjuvants were prepared by treatment with various concentrations of phosphate anion. The isoelectric points (iep) of these adjuvants ranged from 11.0 to 4.6 and the electrophoretic mobilities at pH 7.4 ranged from 2.0 to -3.3 microns cm/V s. The line broadening of the (020) band of the X-ray diffraction pattern indicated that treatment with phosphate anion did not change the primary crystallite dimension. Adsorption at pH 7.4 of positively charged lysozyme (iep = 11.1) was directly related to the negative surface charge of the adjuvant. No adsorption occurred when the surface charge was positive. In contrast, negatively charged ovalbumin (iep = 4.6) was adsorbed by all of the adjuvants at pH 7.4, although the adsorptive capacity was the greatest when the surface charge was positive. The results indicate that adsorptive forces in addition to the electrostatic attractive force play an important role in the adsorption of some proteins by aluminum hydroxide adjuvant. It is believed the structurally flexible proteins, like ovalbumin, exhibit more complex adsorption behavior than structurally rigid proteins, like lysozyme, for which adsorptive behavior can be explained by electrostatic forces.

Adsorption↗