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PubMed2006

Reduction of disinfection by-products precursors by nanofiltration process.

This research is dedicated to determine the rejection ratios of disinfection by-products (DBPs) precursors including resorcinol, phloroglucinol, 3-hydroxybenzoic acid, and tannic acid solution in the presence of calcium by nanofiltration with NF70 membrane. The rejections of these model compounds also were studied at various compositions of a feed solution by changing pH and concentrations of model compounds. It was found that the model compound rejection and membrane permeability increase with pH due to the conformational transformation of ionizable molecules and electric interaction between the model compounds and NF70 membrane. The interactions of model compounds with calcium have no significant effect on model compounds retentions. Because of the complexation of calcium with model compounds, calcium rejection rises with the presence of model compounds and with an increase of pH.

Calcium↗
PubMedDate not supplied

Comparison of mineral trioxide aggregate and calcium hydroxide as pulpotomy agents in young permanent teeth (apexogenesis).

PURPOSE: The purpose of this study was to compare mineral trioxide aggregate (MTA) with calcium hydroxide (Ca(OH)2) clinically and radiographically as a pulpotomy agent in immature permanent teeth (apexogenesis). METHODS: Fifteen children, each with at least 2 immature permanent teeth requiring pulpotomy (apexogenesis), were selected for this study. All selected teeth were evenly divided into 2 test groups. In group 1, the conventional Ca(OH)2pulpotomy (control) was performed, whereas in group 2, the MTA pulpotomy (experimental) was done. The children were recalled for clinical and radiographic evaluations after 3, 6, and 12 months. RESULTS: The follow-up evaluations revealed failure due to pain and swelling detected at 6 and 12 months postoperative evaluations in only 2 teeth treated with Ca(OH)2. The remaining 28 teeth appeared to be clinically and radiographically successful 12 months postoperatively. Calcific metamorphosis was a radiographic finding in 2 teeth treated with Ca(OH)2 and 4 teeth treated with MTA. CONCLUSIONS: Mineral trioxide aggregate showed clinical and radiographic success as a pulpotomy agent in immature permanent teeth (apexogenesis) and seems to be a suitable alternative to calcium hydroxide.

Aluminum Compounds↗
PubMed1991

Absorption and degradation of sevoflurane and isoflurane in a conventional anesthetic circuit.

Soda lime and Baralyme degrade sevoflurane, the rate of degradation being a direct function of temperature. We tested whether this degradation would impede the development of an anesthetizing concentration of sevoflurane (compared with isoflurane, a compound that is not degraded) in a circle-absorption system having an increased temperature consequent to (a) carbon dioxide production (200 mL/min) and absorption; and (b) a low inflow rate (70 mL/min). We also measured the temperatures reached in various parts of the absorption system when used in clinical practice, finding that peak temperatures usually reached 37 degrees - 46 degrees C when low inflow rates (500 mL/min) were applied. The tests in the model system demonstrated that soda lime and Baralyme absorbed both sevoflurane and isoflurane, and that both absorbants degraded sevoflurane but not isoflurane. Baralyme produced a fourfold greater degradation of sevoflurane vapor than did soda lime (0.66 mL/min compared with 0.17 mL/min). However, except for a slight delay at the start of anesthesia, neither absorption nor degradation should noticeably affect the requirement for anesthetic delivery in clinical practice, even in low-flow systems.

Absorption↗
PubMedDate not supplied

[Raman spectrometry applied to calcified tissue and calcium-phosphorus biomaterials].

The rigid part of the human body consists essentially of carbonated apatite (calcium phosphate). Biologists don't have any tools to study this "mineral" phase, though its origin is organic. A new approach of some compounds like enamel or bone is obtained with the Raman micro-characterisation by a very fine analysis of chemical bonds in a micrometric scale. This method allows the characterisation, the analysis and the dosage of ions, like carbonate, acid phosphates, proteins and fatty acids. The identification of other organic or mineral compounds (e.g. calcium carbonate, calcium oxide, substitutant ions...) is also possible. The Raman microspectrometry can also be used to study the chemical and physical properties of biomaterials and their evolution after implantation in a dental or bone site. On synthetical calcium phosphate, beta-TCP, brushite and hydroxyapatite can be distinguished and the impurities found in plasma spray deposits can be measured. The detection of alpha-, beta-, or gamma-pyrophosphates could be obtained in some commercial beta-TCP. The Raman microspectrometry is the only non-destructive method which allows the identification of the chemical bonds in a micrometric scale and gives the "fingerprint" of the studied component.

Animals↗
PubMed2004

Perforation repair and one-step apexification procedures.

As with any dental treatment, procedural mishaps can occur during root canal therapy. One such occurrence is the perforation of a root or pulpal floor. After a perforation occurs, the goals are to "sterilize" (decontaminate) the site and then seal the perforation. The material most widely used in endodontics to seal perforations is mineral trioxide aggregate (MTA). MTA us extremely biocompatible, and it has been shown historically that osteoidlike material grows right into MTA. The technique of one-step apexification offers an alternative to draw-out cases with several medicament-changing appointments that often result in a failed attempt at root-end closure. With the favorable histologic response of MTA, this material is the best current choice for this procedure. Completion of these cases in an effective and efficient way allows for permanent restorations to be done in a more timely manner, prolonging the longevity of these teeth.

Aluminum Compounds↗
PubMed2006

Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions.

OBJECTIVE: The objective of this study was to evaluate periapical repair following retrograde filling using different root-end filling materials. STUDY DESIGN: After induction of periapical lesions, 48 root canals from dog teeth were partially filled. Endodontic surgery was performed and 3 different materials were used for root-end filling: Sealer 26, Sealapex plus zinc oxide, or mineral trioxide aggregate (MTA). No additional procedures were performed in the control group after partial filling of the root canal. After 180 days, the animals were killed, the maxillas and mandibles were removed, and specimens were submitted for histologic processing. RESULTS: Histopathologic analysis revealed similar periapical repair for the groups in which Sealer 26, Sealapex plus zinc oxide, and MTA were used (P > .05). The control group showed unsatisfactory periapical repair (P < .05). CONCLUSION: There was no difference in periapical tissue healing after retrograde filling with the tested materials, which indicates that these 3 root-end filling materials are equally useful.

Aluminum Compounds↗
PubMedDate not supplied

Comparison of apexification with mineral trioxide aggregate and calcium hydroxide.

PURPOSE: The aim of this study was to compare mineral trioxide aggregate (MTA) with calcium hydroxide [Ca(OH)2] clinically and radiographically as materials used to induce root-end closure in necrotic permanent teeth with immature apices (apexification). METHODS: Fifteen children, each with at least 2 necrotic permanent teeth requiring root-end closure (apexification), were selected for this study. All selected teeth were evenly divided into 2 test groups. In group 1, the conventional calcium hydroxide apexification (control) was performed, whereas in group 2, the MTA apexification (experimental) was done. The children were recalled for clinical and radiographic evaluations after 3, 6, and 12 months. RESULTS: The follow-up evaluations revealed failure due to persistent periradicular inflammation and tenderness to percussion detected at 6 and 12 months postoperative evaluation in only 2 teeth treated with Ca(OH)2. The remaining 13 teeth appeared to be clinically and radiographically successful 12 months postoperatively. None of the MTA-treated teeth showed any clinical or radiographic pathology. CONCLUSIONS: Mineral trioxide aggregate showed clinical and radiographic success as a material used to induce root-end closure and is a suitable replacement for calcium hydroxide for the apexification procedure.

Aluminum Compounds↗
PubMed1984

Interactions of lidocaine and calcium in blocking the compound action potential of frog sciatic nerve.

The exact role of calcium in nerve conduction in neurons that have been blocked by local anesthetics remains controversial. Recently, attention has been drawn to the importance of examining both frequency-dependent and nonfrequency-dependent conduction block, since it is felt that frequency-dependent block provides a model that more closely approximates the normal physiologic state. The present study was designed to examine the effects of calcium on both the nonfrequency-dependent and frequency-dependent components of lidocaine nerve block. Desheathed, whole sciatic nerves from frogs were placed in a sucrose gap chamber and stimulated by trains of 20 impulses at frequencies from 3 to 90 Hz at supramaximal intensity for activation of the compound action potential. After control studies, the nerve was bathed by a frog Ringer's solution containing calcium concentrations, which increased from 0.0 mM to the physiologic value of 2.0 mM with or without 0.5 mM lidocaine. Compound action potentials were measured, and both frequency-dependent block and nonfrequency-dependent block were compared in each solution. Low calcium concentrations significantly enhanced both nonfrequency- and frequency-dependent lidocaine block. The effect of low concentrations of calcium was greater at higher frequencies of stimulation.

Action Potentials↗
PubMed2002

Exarticulation and reimplantation utilizing guided tissue regeneration: a case report.

The extraction and reimplantation of teeth is a technique that has been practiced for many years, resulting in successful retention of teeth for up to 30 years. Although evidence confirming the advantages of this technique is limited, clinical observations and histologic examinations have revealed some important factors that are prerequisites for success: limitation of the time the tooth is exposed to the extraoral environment and preservation of vital periodontal tissue attachments on root surfaces. The latter goal can be achieved by gentle, atraumatic removal of the tooth from its socket, and hence the term exarticulation and reimplantation is more representative of the technique. In the present case report, a maxillary lateral incisor with a developmental defect was treated by exarticulation and reimplantation and application of calcium sulfate. Exarticulation and reimplantation seems to be a useful clinical procedure, but controlled studies are required to confirm its efficacy.

Adult↗
PubMed2005

Apexification: a review.

This paper reviews the rationale and techniques for treatment of the non-vital immature tooth. The importance of careful case assessment and accurate pulpal diagnosis in the treatment of immature teeth with pulpal injury cannot be overemphasized. The treatment of choice for necrotic teeth is apexification, which is induction of apical closure to produce more favorable conditions for conventional root canal filling. The most commonly advocated medicament is calcium hydroxide, although recently considerable interest has been expressed in the use of mineral trioxide aggregate. Introduction of techniques for one-visit apexification provide an alternative treatment option in these cases. Success rates for calcium hydroxide apexification are high although risks such as reinfection and tooth fracture exist. Prospective clinical trials comparing this and one-visit apexification techniques are required.

Aluminum Compounds↗
PubMed2006

Effect of mineral trioxide aggregate on proliferation of cultured human dental pulp cells.

AIM: To investigate the effect of mineral trioxide aggregate (MTA) on the proliferation of human dental pulp (HDP) cells ex-vivo. METHODOLOGY: Human dental pulp cells were cultured with MTA or calcium hydroxide-containing cement (Dycal) using culture plate inserts. Control cells were cultured with culture plate inserts only. Cell proliferation was measured for up to 14 days using a Cell Counting kit, and the concentration of calcium ions released from the tested materials was assessed using a Calcium E-test kit. To confirm that the effect of MTA was attributable to released calcium ions, cell proliferation was measured in the presence of exogenous calcium chloride as a source of calcium ions while in the absence of MTA. RESULTS: Mineral trioxide aggregate significantly stimulated cell proliferation after 12 days, whereas Dycal had no such effect. The number of calcium ions released from MTA was significantly higher than that released from Dycal. Following the addition of calcium chloride, cell proliferation increased in a dose-dependent manner after 12 days. Moreover, cell proliferation showed a similar pattern whether a given concentration of calcium ions was produced by calcium chloride or by release from MTA. CONCLUSIONS: In this ex-vivo study, the elution components such as calcium ions from MTA had higher proliferation ability of HDP cells than control and Dycal.

Adult↗
PubMed2003

Mineral trioxide aggregate (MTA) and calcium hydroxide as pulp-capping agents in human teeth: a preliminary report.

AIM: To compare mineral trioxide aggregate (MTA) with calcium hydroxide when used as pulp-capping materials in human teeth. METHODOLOGY: Eleven pairs of maxillary third molars in subjects between 20 and 25 years of age were subjected to mechanical pulp exposure. The exposed pulps were capped with MTA or calcium hydroxide, covered with ZOE and restored with amalgam. A total of 14 teeth were extracted after periods of 1 week (two molars) 2 months (three molars), 3 months (five molars), 4 months (two molars) and 6 months (two molars). RESULTS: Histological evaluation demonstrated less inflammation, hyperaemia and necrosis plus thicker dentinal bridge and more frequent odontoblastic layer formation with MTA than calcium hydroxide. CONCLUSIONS: Although the results favour the use of MTA, more studies with larger samples and a longer follow up are suggested.

Adult↗
PubMed2006

Ferrocenyl compound as a multiresponsive calcium chemosensor with remarkable fluorescence properties in CH3CN.

We have synthesized a novel disubstituted ferrocenyl compound [Fe(C5H4CO(CH=CH)2C6H4NEt2)2] (3) that displays a remarkable fluorescence quantum yield (1.1 x 10(-1)) in acetonitrile, and we have studied its capacity for calcium detection in depth using both electrochemical and optical techniques in this medium. The results of our NMR analysis reveal that the ligand-calcium interaction is CO-centered and that an uncommon equilibrium occurs between 3 and calcium triflate, involving five species of different stoichiometries. In contrast, our analysis of the UV-vis absorption data indicates that only three species of different stoichiometries are formed when calcium perchlorate is used with 3. Mass spectrometry measurements provide strong support for the formation of all these different species in solution. In addition, the electrochemical detection of calcium triflate by 3 leads to an irreversible Fe(II)/Fe(III) oxidation process with an unusual negative shift (-60 mV) caused by the (n)Bu4NBF4 salt effect on the Ca2+-3 interaction process. Compound 3 can also be an original optical probe to detect calcium perchlorate over a wide range of salt concentration by UV-vis absorption spectroscopy. The most original and intriguing property of compound 3 is that it exhibits an unprecedented "multistep" fluorescence behavior upon addition of this salt.

Acetonitriles↗
PubMed1987

Comparison of the localization of chromosome damage induced by calcium chromate and nickel compounds.

Chromosomal aberrations were studied in Chinese hamster ovary cells and in C3H10T1/2 cells following treatment with NiCl2, crystalline NiS, and CaCrO4. All three compounds caused an increase in chromosomal aberrations in a concentration- and time-dependent fashion. The chromosomal aberrations induced by NiCl2 and crystalline NiS occurred predominantly in heterochromatic regions of the chromosomes. Additionally, treatment of cells with crystalline NiS and to a smaller extent long-term treatment with NiCl2 caused a preferential effect on the condensation state of the heterochromatic long arm of the X-chromosome in hamster cells. In contrast, treatment of cells with CaCrO4 did not induce aberrations preferentially in heterochromatin. These results are interesting because nickel(II), which is thought to be the ultimate carcinogen of nickel compounds, binds poorly to DNA, is weakly mutagenic, but induces chromosome damage, probably because of its interaction with nuclear proteins in heterochromatin. Chromate binds to DNA, is mutagenic, and interacts with chromatin randomly.

Calcium Compounds↗
PubMed2006

Endodontic treatment of dens invaginatus: a 5-year follow-up.

Dens invaginatus is an anomaly of the tooth formation of embryonic origin that presents itself in several morphologic types. The complex anatomy of these teeth makes nonsurgical endodontic treatment complex and more so when its apex is immature. The 2 cases reported illustrate the nonsurgical endodontic management of a dens invaginatus type II and type III with an immature apex and periapical lesions, in which mineral trioxide aggregate (MTA) in one case, and calcium hydroxide in the other one, were the materials used. A 5-year follow-up of both cases shows a complete periapical healing with bone formation at the site of the lesions.

Adolescent↗