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At least 307 records · Page 17Linked to original sources
PubMed2005

A comparative prospective randomized clinical study of MTA and IRM as root-end filling materials in single-rooted teeth in endodontic surgery.

OBJECTIVE: Randomized clinical prospective study to evaluate the application of MTA and IRM as retrograde sealers in surgical endodontics. STUDY DESIGN: One hundred single-rooted teeth were surgically treated. After randomization, MTA or IRM was used as a retrosealer. Radiographs were taken 1 week, 3 months, and 1 year postoperatively. Assessment was performed by 2 independent assessors 1 year after surgery. Both treatment groups were homogeneous in their composition, and clinical features and radiographic findings were classified according to Rud's classification. RESULTS: Complete healing was observed in 64% of the MTA-treated teeth vs 50% of the IRM-treated teeth. Incomplete healing was seen in 28% (MTA) vs 36% (IRM), and unsatisfactory in 6% (MTA) vs 14% (IRM). Only 1 failure was seen (MTA). No statistically significant differences were found between the 2 retrofilling materials. CONCLUSION: As root-end filling materials in this clinical prospective randomized design on single rooted teeth, MTA and IRM had the same clinical effectiveness.

Adolescent↗
PubMed2006

Genotoxicity in primary human peripheral lymphocytes after exposure to regular and white mineral trioxide aggregate.

OBJECTIVE: Taking into consideration that DNA damage plays an important role in carcinogenesis, the purpose of this study was to evaluate whether regular and white mineral trioxide aggregate (MTA) are able to induce genetic damage in primary human cells. STUDY DESIGN: Human peripheral lymphocytes obtained from 10 healthy volunteers were exposed to 2 presentation forms of MTA at final concentrations ranging from 1 to 1000 microg/mL for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (phosphate buffer solution, PBS) for 1 hour at 37 degrees C and the positive control group was treated with hydrogen peroxide (at 100 microM) for 5 minutes on ice. Results were analyzed by the Friedman nonparametric test. RESULTS: The results pointed out that either regular or white MTA in all concentrations tested did not induce DNA breakage in human peripheral lymphocytes as depicted by the mean tail moment. CONCLUSION: In summary, our results indicate that exposure to MTA may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single cell gel (comet) assay.

Adult↗
PubMed2006

Biocompatibility of furcal perforation repair material using cell culture technique: Ketac Molar versus ProRoot MTA.

OBJECTIVE: The objective of this study was to evaluate the cytotoxicity of furcal perforation repair materials, GI and MTA, using cell culture technique. STUDY DESIGN: The extract of ProRoot MTA and Ketac Molar were treated on PDL cells in a 96-well tissue-culture plate. Cell proliferation after an incubation period of 3 days was determined by using MTT assay. RESULTS: The growth of cultured human periodontal fibroblast cells were suppressed by both perforation repair materials. The percent of cell viability in the Ketac Molar group was lower than in the ProRoot MTA group (P = .000). CONCLUSIONS: Although Ketac Molar has the advantage of adhering to dentine, it is more cytotoxic to the PDL cells than MTA. In selecting the perforation repair material, it is recommended not only to consider the sealing ability of the material with dentine but also the biocompatibility of material to the underlying tissue.

Aluminum Compounds↗
PubMed2006

Evaluation of the formocresol versus mineral trioxide aggregate primary molar pulpotomy: a meta-analysis.

OBJECTIVE: To apply meta-analysis to compare the clinical and radiographic effects of mineral trioxide aggregate (MTA) with formocresol (FC) when used as wound dressing for pulpotomy of primary molars. STUDY DESIGN: The study list was obtained by searching MEDLINE, The Cochrane Library, EMBASE, and SCI. Only those papers that met the inclusion criteria were analyzed. RESULTS: Six studies met the inclusion criteria. There was significant difference between the success rates of FC- and MTA-treated pulpotomized primary molars (P < .05). Clinical assessments and radiographic findings of the MTA versus FC pulpotomy suggested that MTA was superior to FC in pulpotomy resulting in a lower failure rate, with the RR (Relative Risk) being 0.32 (95% confidence interval [CI] 0.11 to 0.90) and 0.31 (95% CI 0.13 to 0.74), respectively. Internal root resorption happened less in the MTA group with RR 0.29, 95% CI 0.11 to 0.77. CONCLUSION: MTA induces less undesirable responses and might be FC's suitable replacement.

Aluminum Compounds↗
PubMed2005

Precipitation recovery of boron from wastewater by hydrothermal mineralization.

It is well known that boric acid exhibits various toxic effects on plant, animal and human beings even at very low concentrations. Thus, the development of boron-removal technique from wastewater has been intensively investigated. In this study, a new hydrothermal treatment technique was developed to recover boron as recyclable precipitate Ca(2)B(2)O(5).H(2)O from aqueous solutions. As a result, it was found that the hydrothermal treatment using calcium hydroxide as a mineralizer converted boron in the aqueous media effectively into calcium borate, Ca(2)B(2)O(5).H(2)O. In the optimal hydrothermal condition, more than 99% of boron was collected from the synthetic wastewater of 500 ppm. Thus, the present hydrothermal treatment in the presence of calcium hydroxide is recommended as one of the effective techniques to recover boron from aqueous media.

Borates↗
PubMed2006

Agglomeration of struvite crystals.

Struvite crystallisation is widely studied as a way to remove phosphorus from wastewater effluents and simultaneously generates a valuable product for the fertiliser industry. However, to date, some crystallisation processes experimented at either pilot/or full scale face problems linked to the formation of fines. This paper presents results on the investigation of struvite agglomerative properties and the possible application of coagulants and/or flocculants to remove fines. Coagulants investigated were hydrolysing metals salts (Al(3+) and Fe(3+)), calcium compounds and a cationic polymer, polydiallyldimethylammoniumchloride (polyDADMAC). The effects of a natural flocculant (alginate) have also been tested. Results demonstrated that destabilisation of struvite particles by chemical addition was feasible and identified polyDADMAC as a good option for the agglomeration of struvite particles. However, optimisation of its dosage under typical pH conditions for struvite formation showed floc formation to be very pH sensitive.

Alginates↗
PubMed2003

Saturation of human saliva with respect to calcium salts.

It may be assumed that free ionic concentrations of calcium and phosphate in resting saliva tend to equilibrate with those in plaque fluid, and that salivary data can therefore be used to illustrate chemical conditions in both saliva and plaque. In the present study, salivary data collected from the literature or obtained in our laboratory were used to calculate degrees of super- and undersaturation with respect to apatites, brushite, beta-tricalcium phosphate, octacalcium phosphate, calcium carbonate and calcium fluoride in the pH range from 3 to 9. Concentrations of calcium, phosphate, fluoride, carbonate, and background ion strength of resting parotid saliva, resting submandibular saliva, and resting and stimulated whole saliva were entered into a computer program, and curves illustrating saturation in the pH range 3-9 constructed. It was found that oral fluids are supersaturated with respect to apatites above pH 5.3 and with respect to octacalcium phosphate and beta-tricalcium phosphate above pH 6. Parotid saliva was undersaturated with respect to brushite whilst submandibular saliva was supersaturated with respect to that salt in the pH range 6-8. Stimulated whole saliva with 25 mmol/l carbonate became supersaturated with respect to calcium carbonate only above pH 7.3, which may explain the absence of this salt in the human oral cavity. To maintain the saturation of oral fluids with respect to calcium fluoride, i.e. to ensure its survival in the mouth required 6 ppm fluoride in the aqueous phase. Therefore, this salt, the outcome of topical fluoride therapy, will inevitably dissolve in the oral fluids.

Adult↗
PubMed2003

Calcium hypochlorite as a disinfecting additive for dental stone.

STATEMENT OF PROBLEM: Dental casts come into direct contact with impression materials and other items that are contaminated by saliva and blood from a patient's mouth, leaving the casts susceptible to cross-contamination. Topical methods of disinfecting casts are difficult to control, while immersion methods are potentially destructive. Thus, an additional method to control cross-contamination between patients and laboratory personnel is needed. PURPOSE: This study was undertaken in an attempt to develop a dental stone with disinfecting properties and adequate compressive and tensile strengths. MATERIAL AND METHODS: Calcium hypochlorite [Ca(OCl)(2)] in aqueous solution in concentrations from 0 to 1.5% was tested as a disinfecting additive to type V dental stone. The compressive and tensile strength properties of the modified stone were measured (MPa) using a universal testing machine at a consistency similar to unmodified stone. Strength data were analyzed by 1-way ANOVA and post hoc Tukey-Kramer procedure (alpha < or =.05). To measure the disinfecting ability, the effect on Bacillis subtilis bacteriophage phi29 was tested in triplicate to find the minimum concentration at which no phage was detected. Additionally, 3 impressions were disinfected with CaviCide, and 3 impressions rinsed in water served as controls. RESULTS: In general, the effect of adding the disinfectant to the stone was a decrease in strength. Exceptions were the dry compressive strength, for which there was a significant increase in strength (P=.048) at 0.5%, and the wet compressive and wet tensile strength, which showed no significant difference between the 1.5% and the control. When Ca(OCl)(2) was added at the concentration 0.5% (2765 ppm available chlorine), the gypsum had acceptable mechanical properties; dry compressive strength was 78.86 +/- 4.12 MPa, and dry tensile strength was 10.64 +/- 1.27 MPa, compared to control values of 67.85 +/- 6.28 and 13.41 +/- 1.24 MPa, respectively. At concentrations of 0.3% and higher (36 1650 ppm of available chlorine), calcium hypochlorite was able to completely inactivate phi29. CONCLUSION: It is possible to prepare a type V dental stone that contains a disinfectant, has adequate mechanical properties, and will reduce numbers of residual microorganisms. For example, stone mixed with water containing 0.5% Ca(OCl)(2) meets these criteria.

Analysis of Variance↗
PubMed1998

Calcium deficiency alters chorda tympani nerve responses to oral calcium chloride.

As a preliminary examination of the influence of calcium deficiency on gustatory sensitivity to calcium, we recorded electrophysiological responses of the chorda tympani nerve of calcium-replete and calcium-deprived rats. Relative to rats fed calcium-replete diet, rats fed low calcium diet had lower electrophysiological response thresholds to CaCl2 (300 vs. 30 microM) and calcium lactate (300 vs. 100 microM) but not NaCl. The calcium-deprived animals had a greater chorda tympani response to 30, 100 and 300 microM CaCl2 and 30 and 100 microM calcium lactate but a smaller chorda tympani response to 30, 100 and 300 mM CaCl2 and to 100 mM MgCl2. A behavioral study using an ascending series of 48-h two-bottle preference tests showed that the threshold for acceptance of CaCl2 was similar to the electrophysiological threshold (310 microM in replete rats, 100 microM in calcium-deprived rats). These findings raise the possibility that changes in calcium status influence the perception of calcium, which, in turn, influences calcium intake.

Animals↗
PubMed2003

Coagulation-flocculation pretreatment of sanitary landfill leachates.

Sanitary landfill leachates are considered as heavily polluted industrial wastewaters, presenting significant time and spatial variations of their physical-chemical parameters. Special care is required for their efficient treatment and disposal. The main aim of this work was to examine the application of coagulation-flocculation for the treatment of raw and partially stabilized leachates. Jar-test experiments were employed in order to determine the optimum conditions for the removal of organic matter and color, i.e. coagulant-flocculant combination, effective dosage and pH control. Ferric chloride, aluminium sulphate and lime were tested as conventional coagulants, whereas four commercial polyelectrolytes were co-examined: one anionic, two cationic and a non-ionic polymer. High chemical oxygen demand (COD) removal capacities (about 80%) were obtained during the addition of ferric chloride to the partially stabilized leachates, whereas low COD reductions (i.e. lower than 35%) were measured during the addition of coagulants in the raw samples. The addition of polyelectrolytes and pH adjustment in the alkaline region were found to affect slightly the removal of pollutants. The physico-chemical process may be used as a useful pretreatment step, especially for fresh leachates, prior to biological treatment, or as a post-treatment (polishing) step for partially stabilized leachates.

Alum Compounds↗
PubMed1995

Investigation of mutagenicity of mineral trioxide aggregate and other commonly used root-end filling materials.

Little information is available regarding the mutagenicity of root-end filling materials. To study mutagenicity of Intermediate Restorative Material (IRM), Super-EBA, and a potential root-end filling material, mineral trioxide aggregate (MTA), strains of Salmonella typhimurium LT-2 (TA 98, R-factor strain and TA 1535, non-R-factor strains) were used in a standard Ames mutagenicity assay. Positive controls (S9 protein and benzo-(a)-pyrene and N-methyl-N'-nitro-N-nitrosoguanidine) operated properly. No increase in revertant bacteria colony counts occurred with any of the test materials. Based on these results, it seems that IRM, Super-EBA, and MTA are not mutagenic as measured by the Ames Test.

Aluminum Compounds↗
PubMed1997

In vitro study of intradentinal calcium diffusion induced by two endodontic biomaterials.

The aim of this in vitro study was to assess intratubular calcium penetration induced by two root canal restoration materials, one calcium oxide based, and the other calcium hydroxide based. Pig teeth were restored with no preliminary root canal preparation. The filing materials were left in place for 8, 15, or 21 days. The samples were then examined using various microanalytical techniques and, in parallel, by backscattered electron image (BEI) scanning electron microscopy. The Ca/P ratios obtained by microanalysis were higher for samples restored with calcium oxide. In addition, the distances over which the ratios increased were also greater than those obtained using calcium hydroxide. BEI photographs confirm these results and show corresponding retrodiffusion fringes.

Animals↗
PubMed1997

An ultrastructural study of root canal walls in contact with endodontic biomaterials.

The aim of this in vitro study was to compare structural and ultrastructural changes to the unmineralized extracellular matrix after using two root canal restoration materials, one calcium hydroxide based and the other calcium oxide based. Pig teeth were restored with no preliminary root canal preparation. The filling materials were left in the root canals for 3, 8, 15, or 21 days. Observations were carried out by scanning electron microscopy. Results showed that when the calcium oxide-based material was used, it penetrated tubules and the unmineralized extracellular matrix material was reduced to a minimum. Teeth filled with the calcium hydroxide-based material were similar to control samples with an intact predentine. These observations suggest that the calcium oxide-based material induces changes in the unmineralized extracellular matrix of the endodontium.

Animals↗
PubMed1998

Cellular response to Mineral Trioxide Aggregate.

This investigation studied the cytomorphology of osteoblasts in the presence of Mineral Trioxide Aggregate (MTA) and examined cytokine production. MTA and Intermediate Restorative Material (IRM) were prepared and placed in separate Petri dishes. Osteoblasts (cell-line MG-63), grown to confluence in Hams F12/Dulbecco's modified Eagle's medium, were seeded into the dishes, which were incubated for 1 to 7 days. The specimens were viewed by scanning electron microscopy. For cytokine evaluation, cells were grown either alone or in other dishes containing the test materials for 1 to 144 h. Media were removed for ELISA analysis of interleukin (IL)-1 alpha, IL-1 beta, IL-6, and macrophage colony-stimulating factor. Scanning electron microscopy revealed healthy cells in contact with MTA at 1 and 3 days; in contrast, cells in the presence of IRM appeared rounded. The ELISA assays revealed raised levels of all ILs at all periods when cells were grown in the presence of MTA; in contrast, cells grown alone or with IRM produced undetectable amounts. The macrophage colony-stimulating factor was produced by cells irrespective of the group. It seems that MTA offers a biologically active substrate for bone cells and stimulates IL production.

Aluminum Compounds↗
PubMed1998

Evaluation of setting properties and retention characteristics of mineral trioxide aggregate when used as a furcation perforation repair material.

Furcation perforations were created in 32 extracted maxillary and mandibular molars. The perforations were prepared in the center of the pulp chamber floor parallel to the long axis of each tooth and a saline-moistened Gelfoam matrix was placed below the perforation to simulate a clinical condition. The teeth were randomly divided into four groups, and the perforations were all repaired with mineral trioxide aggregate (MTA) and then covered with either a wet or dry cotton pellet for 24 or 72 h. Instron testing was used to measure the force required to displace the material from the perforation. The force measurements showed that MTA resisted displacement at 72 h to a significantly greater level than at 24 h (p < 0.05). When slight displacement occurred at 24 h the material demonstrated the ability to re-establish resistance to dislodgement from the dentin wall. The presence of some moisture in the perforation during placement was advantageous in aiding adaptation of MTA to the walls of the perforation, but there was no significant difference in MTA retention when a wet or dry cotton pellet was placed in the pulp chamber during the setting time (p > 0.05).

Aluminum Compounds↗
PubMed1998

Bacterial leakage of mineral trioxide aggregate as compared with zinc-free amalgam, intermediate restorative material, and Super-EBA as a root-end filling material.

Several dye leakage studies have demonstrated the fact that mineral trioxide aggregate (MTA) leaks significantly less than other root-end filling materials. The purpose of this study was to determine the time needed for Serratia marcescens to penetrate a 3 mm thickness of zinc-free amalgam, Intermediate Restorative Material (IRM), Super-EBA, and MTA when these materials were used as root-end filling materials. Fifty-six, single-rooted extracted human teeth were cleaned and shaped with a series of .04 Taper rotary instruments (Pro-series 29 files). Once the canals were prepared in a crown down approach, the ends were resected and 48 root-end cavities were ultrasonically prepared to a 3 mm depth. The teeth were then steam sterilized. Using an aseptic technique, under a laminar air flow hood, the root-end cavities were filled with amalgam, IRM, Super-EBA, and MTA. Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer and served as positive controls. Another four root-end cavities were filled with sticky wax covered with two layers of nail polish and served as negative controls. The teeth were attached to presterilized (ethylene oxide gas) plastic caps, and the root ends were placed into 12-ml vials of phenol red broth. Using a micropipette, a tenth of a milliliter of S. marcescens was placed into the root canal of each tooth. To test the sterility of the apparatus set-up, the root canals of two teeth with test root-end filling materials and one tooth from the positive and negative control groups were filled with sterile saline. The number of days required for S. marcescens to penetrate the four root-end filling materials and grow in the phenol red broth was recorded and analyzed. Most of the samples filled with zinc-free amalgam leaked bacteria in 10 to 63 days. IRM began leaking 28 to 91 days. Super-EBA began leaking 42 to 101 days. MTA did not begin leaking until day 49. At the end of the study, four of the MTA samples had not exhibited any leakage. Statistical analysis of the data indicated Mineral Trioxide Aggregate to be a most effective root-end filling material against penetration of S. marcescens.

Aluminum Compounds↗
PubMed1998

Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model.

The purpose of this study was to evaluate the ability of mineral trioxide aggregate (MTA) and amalgam to seal furcal perforations in extracted human molars using an anaerobic bacterial leakage model. Furcal perforations were made in 39 maxillary and mandibular human molars with a high-speed bur. These were randomly divided into two experimental groups of 18, with the remaining three teeth used as positive controls. Experimental group 1 was repaired with MTA and group 2 with amalgam. Three additional teeth without perforations served as negative controls. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion broth with yeast extract, hemin, menadione, and the chromogenic indicator bromcresol purple was used as the culture broth for Fusobacterium nucleatum. Eight of 18 amalgam samples leaked, whereas none of the 18 MTA samples leaked. MTA was significantly better than amalgam in preventing leakage of F. nucleatum past furcal perforation repairs.

Aluminum Compounds↗