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PubMed2002

Hardness and in vitro wear of a novel ceramic restorative cement.

The aim of the present work was to compare a new ceramic restorative cement for posterior restorations, DoxaDent, with other types of tooth-colored materials for direct use as regards hardness and in vitro wear. Four hybrid resin composites, one polyacid-modified resin composite, one resin-modified glass ionomer cement, one conventional glass ionomer cement, one zinc phosphate cement, an experimental version as well as the marketed version of the ceramic restorative cement, were investigated. Hardness of the materials was tested with the Wallace indentation tester and wear was tested with the ACTA wear machine. All tests were carried out on 2-wk-old specimens. DoxaDent was as hard as the zinc phosphate cement and the hardest resin composite. The ceramic restorative cement wore significantly more than the resin composites, the same as the zinc phosphate cement, and less than the glass ionomer cements. No correlation between hardness and wear was found. It can be concluded that the ceramic restorative cement is a rather hard material but with a relatively low wear resistance.

Aluminum Compounds↗
PubMed2003

Investigation of the marginal adaptation of root-end filling materials in root-end cavities prepared with ultrasonic tips.

AIM: To compare the surface topography of root apices following ultrasonic root-end preparation, and again after root-end fillings submitted to three different finishing techniques. METHODOLOGY: Eighty-one root-end cavities prepared ultrasonically in human canines, were divided at random into three test groups of 27 each. The cavities were filled with Super-EBA, IRM, or ProRoot-MTA and finished by ball burnishing. Eighteen roots from each group received a final finish with either a 30-fluted tungsten carbide finishing bur, or a Zekrya carbide 28 mm bur after storage in water at 37 degrees C for 24 h. The root-end surface topographies were reproduced by means of polyvinylsiloxane impressions and epoxy resin replicas. Scanning electron micrography (SEM) images of each replica were taken prior to and after root-end filling. An image analysis system was used to compare the alteration of the marginal chipping areas and to calculate the gaps located in the dentine/root-end filling interface. RESULTS: When a bur was used to finish the set materials, a significant (P < 0.05) area of marginal chipping was eliminated. The finishing technique did not significantly (P > 0.05) affect the incidence of gaps in groups root-end filled with MTA or IRM. Super-EBA and IRM retrofillings finished with a ball burnisher or a Zekrya bur displayed a significantly (P < 0.05) larger calculated gap area than roots filled with MTA. CONCLUSION: Under this in vitro study, the marginal adaptation of MTA was good with or without finishing procedures. Applying a finishing bur over the condensed and set IRM and Super-EBA created better marginal adaptation.

Aluminum Compounds↗
PubMed2003

Cell and tissue reactions to mineral trioxide aggregate and Portland cement.

OBJECTIVE: Mineral trioxide aggregate (MTA) is being widely used for root-end fillings, pulp capping, perforation repairs, and other endodontic procedures. MTA and Portland cement (PC) have many similar physical, chemical, and biologic properties. PC cement has shown promising potential as an endodontic material in several studies in vitro and in vivo. The purpose of this study was to compare the cytotoxic effect in vitro and the tissue reaction of MTA and Portland cement in bone implantation in the mandibles of guinea pigs. STUDY DESIGN: Millipore culture plate inserts with freshly mixed or set material were placed into the culture plates with already attached L929 cells. After an incubation period of 3 days, the cell morphology and cell counts were studied. Adult male guinea pigs under strict asepsis were anesthetized, during which a submandibular incision was made to expose the symphysis of the mandible. Bilateral bone cavities were prepared and Teflon applicators with freshly mixed materials were inserted into the bone cavities. Each animal received 2 implants, one filled with ProRoot and 1 with PC. The animals were killed after 2 or 12 weeks, and the tissues were processed for histologic evaluation by means of light microscopy. RESULTS: There was no difference in cell reactions in vitro. Bone healing and minimal inflammatory response adjacent to ProRoot and PC implants were observed in both experimental periods, suggesting that both materials are well tolerated. CONCLUSIONS: MTA and PC show comparative biocompatibility when evaluated in vitro and in vivo. The results suggest that PC has the potential to be used as a less expensive root-end filling material.

Aluminum Compounds↗
PubMed1984

Analysis of minor and trace elements in gallstones by induction of characteristic ionising radiation.

In an investigation of the role of trace elements in gallstone formation and of minor and trace elements in gallstone and bile, samples from five patients were analysed using three different techniques for cross-verification: NAA, PIXE, and XRF. In addition, certified standards of bovine liver and oyster tissue from the NBS, Washington, were re-analysed using the different techniques to confirm the accuracy of the experimental procedures. NAA of five gallstones was used for the quantitative analysis of 19 elements with Z greater than 11. The concentrations of Cl, K + Ca, Mn, Fe and Cu + Zn were determined by PIXE and those of Mg, P, S, K and Ca by XRF. In most cases the concentrations were in the range of a few PPB to a few hundred PPM. The spatial distribution of the component elements was obtained using XRF with a scanning electron microscope and the results demonstrated that calcium was present centrally in all the stones. The analysis of gallbladder bile from four patients showed that the calcium concentration was much greater than normal, indicating that calcium and other elements play an important role in stone formation. Infrared spectroscopy showed that the calcium salts were present in gallstones in three compound forms: calcium carbonate, calcium phosphate and calcium bilirubinate. Reasons for the cause of calcium precipitation are discussed.

Bile↗
PubMed2000

Cytotoxicity of mineral trioxide aggregate using human periodontal ligament fibroblasts.

The purpose of the present study was to compare the cytotoxicity of mineral trioxide aggregate (MTA) to other commonly used retrofilling materials, Super-EBA and amalgam. This was accomplished using a cell viability assay for mitochondrial dehydrogenase activity in human periodontal ligament fibroblasts after 24-hr exposure to extracts of varying concentrations of the test materials, in both freshly mixed and 24-hr set states. Methyl methacrylate 2% (vol/vol) served as the positive control, and complete culture medium served as the negative control. Differences in mean cell viability values were assessed by ANOVA (p < 0.05). In the freshly mixed state, the sequence of toxicity was amalgam > Super-EBA > MTA. In the 24-hr set state the sequence of toxicity at a low extract concentration was Super-EBA > MTA, amalgam, and Super-EBA > amalgam > MTA at a higher extract concentration. This study supports the use of MTA in the root-end environment.

Aluminum Compounds↗
PubMed2000

Effects of the Nd:YAP laser on coronal restorative materials: implications for endodontic retreatment.

With new wavelengths that allow light transmission by optical fibers, the laser is now often used in endodontics either during treatment or retreatment. The aims of this study were to (i) specify the effects of laser irradiation on restorative materials in terms of topographic effects and (ii) describe different protocols for the first steps of retreatment. The laser used in this study was an optical fiber Nd:YAP (Lokki dt, Vienne, France) with a wavelength of 1.34 microns. Samples of the following restorative materials were prepared: amalgam, composite, permanent and temporary cements, and prosthodontic alloy. The handpiece of the Nd:YAP laser was fixed perpendicular to the surface of the different preparations. All trials were performed with the fiber tip either in contact with or at a distance of 2 mm from the material. The surface effects in all cases were (i) the creation of craters in the center of the lased areas, (ii) a border of fusion material at the edge of the craters, and (iii) cracks or fractures at a distance from the target areas. For the cements, amalgam and composite, the effects included a projection of material from the center to the edge of the lased area and/or the apparent photovolatization of light particles. For all materials the laser induced deeper absorption in the areas of direct contact than when it was held at a distance. This suggests that the fiber should be in contact with the restorative material for lasing in the straight part of the canal when the objective is either to pass through the material or alongside it between material and tooth. If the practitioner cannot determine the direction of the curve of the canal, lasing should be performed at a distance to weaken the material and thus permit more efficient use of an ultrasonic device. Lasing should in all cases be performed under close X-ray monitoring. Provided that sufficient caution is used, the laser may be helpful in removing restorative materials during retreatment.

Absorption↗
PubMed2001

Microleakage of root-end filling materials.

The purpose of this study was to evaluate the microleakage of various root-end filling materials using a fluid filtration system. Sixty extracted human single-rooted teeth were used. The crowns were removed, the canals prepared, and root-end fillings placed. The samples were divided into two control and five experimental groups. The root-end filling materials tested were: amalgam, Intermediate Restorative Material (IRM), a dentin-bonded resin, Super-EBA, and mineral trioxide aggregate. The results showed that amalgam root-end fillings demonstrated significantly more microleakage than Super-EBA, dentin-bonded resin, or mineral trioxide aggregate. There was no significant difference between amalgam and IRM. However IRM was also not significantly different from the other three groups. There were no significant differences between the other three groups.

Aluminum Compounds↗
PubMed2002

Sealing ability of mineral trioxide aggregate and super-EBA when used as furcation repair materials: a longitudinal study.

Immediate sealing of furcation perforations enhances the repair process. The purpose of this study was to longitudinally compare the ability of mineral trioxide aggregate (MTA) and Super-EBA to seal furcation perforations. Fifty-one extracted human maxillary molars were decoronated 3 mm above the CEJ, and the roots were amputated 3 mm below the furcation. A #2 high-speed round bur was used to perforate the center of the furcations. The canals were obturated with gutta-percha, and the root ends were sealed with C&B Metabond. Three experimental groups of 15 teeth each were restored with MTA, Super-EBA, or a combination of MTA in the perforation and a Super-EBA dome on the pulpal floor. Six teeth served as controls. Each tooth was affixed to a fluid filtration device and subjected to a pressure of 20 cm H2O. The integrity of the perforation seal was evaluated initially at 30 min for the Super-EBA and the combination groups and at 4 h for the MTA group. Additional measurements were then made at 24 h, 1 week, and 1 month. The controls behaved as expected. A two-way ANOVA revealed a significant difference (p = 0.01) between materials. Tukey's test isolated the difference to Super EBA as producing a superior seal but only at 24 h. There was no significant effect with time (p = 0.57) or the interaction of the materials with time (p = 0.66). All materials sealed the perforations very well. The maximum leakage of all materials was <0.007 microL min(-1) cm H2O(-1).

Aluminum Compounds↗
PubMed2004

Reactions of connective tissue to mineral trioxide aggregate and amalgam.

The purpose of this study was to evaluate the subcutaneous connective tissue reactions to ProRoot, mineral trioxide aggregate (MTA; Dentsply), and Oralloy, high-copper amalgam (Coltene). These materials were placed in polyethylene tubes and implanted into dorsal connective tissue of Wistar albino rats, and tissue biopsies were collected and histologically examined 7, 15, 30, 60, and 90 days after the implantation procedure. The presence of inflammation, predominant cell type, calcification, and thickness of fibrous connective tissue were recorded. Scores were defined as follows: 0, none or few inflammatory cells, no reaction; 1, < 25 cells, mild reaction; 2, 25 to 125 cells, moderate reaction; 3, > or = 125 cells, severe reaction. Fibrous capsule was categorized as "thin" when thickness was < 150 microm and "thick" at > 150 microm. Necrosis and formation of calcification were recorded. Both materials were well tolerated by the tissues in a 90-day evaluation period. One notable finding is the presence of dystrophic calcification in connective tissue adjacent to MTA; this finding is consistent with the hypothesis of hard tissue induction by this material.

Aluminum Compounds↗
PubMed2004

MTA obturation of pulpless teeth with open apices: bacterial leakage as detected by polymerase chain reaction assay.

Polymerase chain reaction (PCR) followed by reverse dot blot was used to detect Enterococcus faecalis leakage through mineral trioxide aggregate (MTA) apical obturations of pulpless teeth with open apices. Prepared root canals of 34 extracted teeth were given a standard apical foramen opening and received orthograde apical obturation with MTA; three groups had 1-, 2-, or 3-mm thickness. Sterilized specimens were inoculated with E. faecalis and incubated in sterile medium. DNA extracted from the specimens was amplified by polymerase chain reaction, which yielded a specific segment of E. faecalis 16S rDNA. On day 10 of incubation, no specimens were contaminated. On day 50, almost 17% of specimens were contaminated, with no statistically significant difference between groups (Chi-square = 0.48; df = 2; p = 0.787). Therefore, MTA provides an adequate seal even in cases of orthograde apical obturation of pulpless teeth with open apices.

Aluminum Compounds↗
PubMed2005

Chemical differences between white and gray mineral trioxide aggregate.

The purpose of this research was to determine and compare the composition of white mineral trioxide aggregate and gray mineral trioxide aggregate. Electron probe microanalysis results indicated that lime (CaO), silica (SiO2), and bismuth oxide (Bi2O3) were the dominant compounds in each case and were present at comparable levels in either of the types of mineral trioxide aggregate analyzed. It was concluded that the most significant differences observed were between the measured concentrations of Al2O3 (+122%), MgO (+130%), and especially FeO (+1000%) when gray mineral trioxide aggregate was compared with white mineral trioxide aggregate.

Aluminum Compounds↗
PubMed2004

Comparative study of white and gray mineral trioxide aggregate (MTA) simulating a one- or two-step apical barrier technique.

This study investigated the use of Mineral Trioxide Aggregate (MTA) as an apical barrier by comparing the sealing ability and set hardness of white and gray MTA. Forty-four root segments were prepared to simulate an open apex. Apical barriers of white and gray MTA were placed to a thickness of 2 mm or 5 mm. The samples were obturated immediately (one-step) or after the MTA set for 24 h (two-steps). After placement in methylene blue dye for 48 h, the samples were sectioned for leakage analysis and microhardness testing of the barrier. Gray MTA demonstrated significantly less leakage than white MTA (p < 0.001), and the two-step technique showed significantly less leakage than one-step (p < 0.006). The 5-mm thick barrier was significantly harder than the 2 mm barrier, regardless of the type of MTA or number of steps (p < 0.01). Results suggested that a 5 mm apical barrier of gray MTA, using two-steps, provided the best apical barrier.

Aluminum Compounds↗
PubMed2005

MTA solubility: a long term study.

The purposes of this long-term study was to assess the amount of soluble material released by Mineral Trioxide Aggregate to a water medium, to determine if the solubility differences between specimens of various water/powder ratio, as demonstrated in a previous study, would be maintained over time, and to measure the pH of the water that was in contact with the specimens. Specimens were processed at 0.28 and 0.33 water/powder ratios, and immersed in water according to the ISO 6876 standard. The specimens were periodically removed to assess salt content release and reimmersed in fresh water. Assay testing was periodically performed over a 78-day period. Results were expressed as Daily Solubility (solubility rate), and Cumulative Solubility. The mathematical projection from Cumulative Solubility to infinite time showed that MTA could solubilize 22.06% at 0.28 water/powder ratio, and 31.095% at 0.33 water/powder ratio of the specimens' mass in regards to their initial dry weight. MTA did maintain a high pH for an extended period of time under these study conditions.

Aluminum Compounds↗
PubMed2005

Periapical tissue responses and cementum regeneration with amalgam, SuperEBA, and MTA as root-end filling materials.

The purpose of this study was to compare the periapical tissue responses and cementum regeneration in response to three widely used root-end filling materials, amalgam, SuperEBA, and Mineral Trioxide Aggregate (MTA). These materials were placed using modern microsurgical techniques on endodontically treated dog premolars and molars. After 5 months, the cell and tissue reactions of surface-stained un-decalcified ground sections were evaluated by light microscopy and statistically analyzed. The major difference in the tissue responses to the three retrofilling materials were the degree of inflammation and types of inflammatory cells, number of fibrous capsule formations, cementum neoformation over these materials, osseous healing and resulting periodontal ligament thickness. MTA showed the most favorable periapical tissue response, with neoformation of cemental coverage over MTA. SuperEBA was superior to amalgam as a root-end filling material.

Aluminum Compounds↗
PubMed2004

Biocompatibility of two commercial forms of mineral trioxide aggregate.

AIM: To examine the biocompatibility of two commercial forms of mineral trioxide aggregate (MTA), by evaluating the morphology of an established cell line. METHODOLOGY: The two cements were cast on glass cover slips and cured for 1 or 28 days. Saos-2 osteosarcoma cells were trypsinized and seeded at a density of 1 x 10(5) cells and were then placed in medium over the material-coated coverslips for 1, 5 and 7 days. After these time intervals the media were discarded and the cells fixed. Cell morphological investigation was performed by scanning electron microscopy at various magnifications ranging from x 250 to x 500. The biocompatibility of cement constituents, alusilicate flux and bismuth oxide was also investigated. RESULTS: All cement samples cured for 1 day showed a confluent cell monolayer after 5 and 7 days. The response to both materials was similar. Materials cured for 28 days showed incomplete cell confluence after 1 and 5 days. Alusilicate flux and bismuth oxide did not demonstrate biocompatibility. CONCLUSIONS: The 1-day cured samples of two commercial forms of MTA showed good biocompatibility. However, the 28-day cured samples were less biocompatible after 1 and 5 days.

Aluminum Compounds↗
PubMed2005

Cytotoxicity of MTA and Portland cement on human ECV 304 endothelial cells.

AIM: To evaluate the cytotoxic effects of two brands of mineral trioxide aggregate (MTA) (Pro-Root MTA and MTA Angelus) and Portland cement (PC) on the human ECV 304 endothelial cell line. METHODOLOGY: Endothelial ECV 304 cells were incubated at 37 degrees C in an atmosphere of 95% air, 5% carbon dioxide and 100% humidity for 7 days and grown in F12 medium supplemented with 10% fetal bovine serum with 50 microg mL(-1) of gentamicin sulphate. Effects of the materials on mitochondrial functions were measured by a colorimetric assay. At each experimental time interval (24, 48 and 72 h), a dimethyl-thiazol-diphenyl tetrazolium bromid assay was conducted to measure cell viability. All assays were repeated three times to ensure reproducibility. Results were expressed as average absorbance (A(570/nm)) +/- SD and the data were analysed statistically by one-way analysis of variance and the Bonferroni post-test. A P-value < 0.05 was considered statistically significant. RESULTS: No statistically significant difference was shown between any of the experimental materials (P > 0.05). CONCLUSIONS: The two brands of MTA analysed, as well as the PC, initially showed a similar elevated cytotoxic effect that decreased gradually with time allowing the cell culture to become reestablished.

Aluminum Compounds↗
PubMed2006

Mineral trioxide aggregate: a review of the constituents and biological properties of the material.

This paper reviews the literature on the constituents and biocompatibility of mineral trioxide aggregate (MTA). A Medline search was conducted. The first publication on the material was in November 1993. The Medline search identified 206 papers published from November 1993 to August 2005. Specific searches on constituents and biocompatibility of mineral trioxide aggregate, however, yielded few publications. Initially all abstracts were read to identify which fitted one of the two categories required for this review, constituents or biocompatibility. Based on this assessment and a review of the papers, 13 were included in the constituent category and 53 in the biocompatibility category. Relatively few articles addressed the constituents of MTA, whilst cytological evaluation was the most widely used biocompatibility test.

Aluminum Compounds↗