Biomedical subjects

M Torabinejad

Publications and source records attributed to M Torabinejad.

At least 37 records · Page 2Linked to original sources

PubMed1996

Using mineral trioxide aggregate as a pulp-capping material.

This study examined the dental pulp responses in monkeys to mineral trioxide aggregate, or MTA, and a calcium hydroxide preparation when used as pulp-capping materials. After the pulps of 12 mandibular incisors were exposed with a No. 1 round bur, they were capped with either MTA or the calcium hydroxide preparation. After five months, the authors noted no pulpal inflammation in five of six samples capped with MTA, and all six pulps in this group had a complete dentin bridge. In contrast, all of the pulps capped with the calcium hydroxide preparation showed pulpal inflammation, and bridge formation occurred in only two samples. Based on these results, it appears that MTA has the potential to be used as a pulp-capping material during vital pulp therapy.

Aluminum Compounds↗

PubMed1995

Bacterial leakage of mineral trioxide aggregate as a root-end filling material.

Previous dye leakage studies have shown that mineral trioxide aggregate leaks significantly less than other commonly used root-end filling materials. This study determined the time needed for Staphylococcus epidermidis to penetrate a 3-mm thickness of amalgam, Super-EBA, Intermediate Restorative Material (IRM), or mineral trioxide aggregate (MTA) as root-end filling materials. Fifty-six single-rooted extracted human teeth were cleaned and shaped using a step-back technique. Following root-end resection, 48 root-end cavities were filled with amalgam, Super-EBA, IRM, or MTA. Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer (+ control), and another four were filled with sticky wax covered with two layers of nail polish (- control). After attaching the teeth to plastic caps of 12-ml plastic vials and placing the root ends into phenol red broth, the set-ups were sterilized overnight with ethylene dioxide gas. A tenth of a microliter of broth containing S. epidermidis was placed into the root canal of 46 teeth (40 experimental, 3 positive, and 3 negative control groups). In addition, 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 the test bacteria to penetrate various root-end filling materials was determined. Most samples whose apical 3 mm were filled with amalgam, Super-EBA, or IRM began leaking at 6 to 57 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Compounds↗

PubMed1995

Cytotoxicity of four root end filling materials.

Leakage and scanning electron microscopic studies have shown that a mineral trioxide aggregate (MTA) used as root end filling material permits significantly less leakage and has better adaptation than other commonly used root end filling materials. Because these materials are in contact with the periradicular tissues, their cytotoxicity should be evaluated before in vivo tests. Using the agar overlay and radiochromium methods, the cytotoxicity of amalgam, Super EBA, IRM, and the MTA was evaluated. Statistical analysis of the data from the agar overlay technique shows that freshly mixed and set amalgam were significantly less toxic than the rest of tested materials (p< 0.00005). Fresh and set MTA ranked second when tested for cytotoxicity with this technique. Similar statistical tests revealed a significant statistical difference between the toxicity of freshly mixed and set materials after 24 h of incubation with radiochromium-labeled mouse L929 cells. The degree of cytotoxicity of fresh and set materials was MTA least toxic followed by amalgam, Super EBA, and IRM. Based on the results of the cell culture methods used in this study it appears that MTA is a potential root end filling material and warrants further in vivo evaluations.

Agar↗

PubMed1995

Antibacterial effects of some root end filling materials.

In addition to having good sealing ability, root end filling materials should "ideally" have some antibacterial activity to prevent bacterial growth. This investigation compared the antibacterial effects of amalgam, zinc oxide-eugenol, Super EBA and a mineral trioxide aggregate on nine facultative bacteria Streptococcus fecalis, Streptococcus mitis, Streptococcus mutans, Streptococcus salivarius, Lactobacillus species, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, and Escherichia coli B and seven strict anaerobic bacteria, Prevotella (Bacteroides) buccae, Bacteroides fragilis, Prevotella (Bacteroides) intermedia, Prevotella (Bacteroides) melaninogenica, Fusobacterium necrophorum, Fusobacterium nucleatum, and Peptostreptococcus anaerobius. After growing these bacteria on solid media, freshly mixed and 24-h set test materials were placed on the surface of these inoculated media and incubated in the appropriate atmosphere for 24 to 48 h at 37 degrees C. Impregnated discs with the Super EBA liquid were used as positive controls. The antibacterial effects of each material were measured in millimeters and the data were analyzed using one-way and two-way analysis of variance and Scheffé tests to determine the statistical differences between the antibacterial effects of the test materials. Impregnated discs with Super EBA liquid caused varying degrees of growth inhibition for both facultative and strict anaerobic bacteria. Both types of amalgam had no antibacterial effect against any of the bacteria tested in this study. Mineral trioxide aggregate had an antibacterial effect on some of the facultative bacteria and no effect on any of the strict anaerobic bacteria. Zinc oxide-eugenol and Super EBA pastes had some antibacterial effects on both types of bacteria tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Compounds↗

PubMed1995

Physical and chemical properties of a new root-end filling material.

This study determined the chemical composition, pH, and radiopacity of mineral trioxide aggregate (MTA), and also compared the setting time, compressive strength, and solubility of this material with those of amalgam, Super-EBA, and Intermediate Restorative Material (IRM). X-ray energy dispersive spectrometer in conjunction with the scanning electron microscope were used to determine the composition of MTA, and the pH value of MTA was assessed with a pH meter using a temperature-compensated electrode. The radiopacity of MTA was determined according to the method described by the International Organization for Standardization. The setting time and compressive strength of these materials were determined according to methods recommended by the British Standards Institution. The degree of solubility of the materials was assessed according to modified American Dental Association specifications. The results showed that the main molecules present in MTA are calcium and phosphorous ions. In addition, MTA has a pH of 10.2 initially, which rises to 12.5 three hours after mixing. MTA is more radiopaque than Super-EBA and IRM. Amalgam had the shortest setting time (4 min) and MTA the longest (2 h 45 min). At 24 h MTA had the lowest compressive strength (40 MPa) among the materials, but it increased after 21 days to 67 MPa. Finally, except for IRM, none of the materials tested showed any solubility under the conditions of this study.

Aluminum 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↗

PubMed1995

Tissue reaction to implanted super-EBA and mineral trioxide aggregate in the mandible of guinea pigs: a preliminary report.

In vitro sealing ability and biocompatibility tests on mineral trioxide aggregate (MTA) have shown similar or better properties for this material than for existing root-end filling substances. The purpose of this study was to examine the tissue reaction of implanted Super-EBA and MTA in the mandibles of guinea pigs. After anesthetizing seven guinea pigs, raising a tissue flap and preparing two bony cavities, the test materials were placed in Teflon cups and implanted in the mandibles. Two bony cavities without implanted materials were left to heal and used as negative controls. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant was recorded. The tissue reaction to MTA implantation was slightly than that observed with Super-EBA implantation. Based on these results , it seems that both Super-EBA and MTA are biocompatible.

Aluminum Compounds↗

PubMed1995

Comparative investigation of marginal adaptation of mineral trioxide aggregate and other commonly used root-end filling materials.

This study investigated the marginal adaptation of mineral trioxide aggregate (MTA) as a root-end filling material, compared with commonly used root-end filling materials by scanning electron microscopy (SEM). Eighty-eight single-rooted freshly extracted human teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. Following root-end resection and cavity preparation, the root-end cavities were filled with amalgam, Super-EBA, Intermediate Restorative Material (IRM), or MTA. Using a slow-speed diamond saw, 40 roots were longitudinally sectioned into two halves. Resin replicas of resected root ends of the remaining nonsectioned roots were also prepared. After mounting longitudinal sections of roots and resin replicas of resected roots on aluminum stubs, the distance between the test root-end filling materials and surrounding dentin was measured at four points under SEM. Examination of the original samples showed numerous artifacts in the longitudinal sections of the specimens. In contrast, the resin replicas of resected and filled root ends had no artifacts. Statistical analysis of data comparing gap sizes between the root-end filling materials and their surrounding dentin shows that MTA had better adaptation compared with amalgam, Super-EBA, and IRM.

Aluminum Compounds↗

PubMed1995

Effects of vacuuming on dye penetration patterns in root canals and glass tubes.

This study compared the dye leakage pattern of prepared root canals with that of glass tubes, with and without vacuuming. The apical 12 mm of 40 calcified root canals were prepared to tubes with a diameter of 0.5 mm. The coronal end of these canals and 40 glass tubes with similar diameters (12 mm x 0.5 mm) were closed with 2 mm of Cavit. Twenty samples from each group were left empty, and the rest (20) were filled with gutta-percha without sealer. Half of the samples of filled (10) and unfilled (10) specimens were then placed horizontally in 2% methylene blue dye. The other half (10) of the samples from each group were placed in a vacuum (25 mm Hg) and submerged in the dye. Leakage was then measured in millimeters and statistically analyzed using analysis of variance. The 20 empty glass tubes with or without vacuum leaked 17% or less of their lengths. The 20 glass tubes filled with gutta-percha averaged 70.5% leakage. Of those, the 10 glass tubes that were vacuumed had 100% leakage. Empty root canals exhibited mean leakage of 74% without vacuum and 91% of their length with vacuum. Canals filled with gutta-percha leaked a mean of 95.5% of their entire lengths without vacuum and 100% with vacuum (no significant difference). The results showed that filled and unfilled, prepared root canals leaked significantly more than their glass tube counterparts (p < 0.001), and vacuuming may not be necessary for dye leakage studies in filled root canals.

Air↗

PubMed1995

Effect of preflaring on tactile detection of the apical constriction.

The efficacy of tactile detection of the apical constriction in flared and nonflared root canals was examined in 120 root canals of adult patients. In 68 nonflared (group 1) root canals, a #15 or #20 K-file was used to detect ("feel") the apical constriction. In 52 teeth (group 2), Hedstrom files, Gates Gliden drills #2 to #4, and ultrasonic files were used to enlarge the canal orifice and flare the coronal portion of the root canals before testing the apical constriction. After placing a #15 or #20 file in each root canal, a radiograph was taken, and the distance between the tip of the file and the radiographic apex was measured. The location of the file tip was classified into three categories: (a) within 1 mm short of the radiographic apex; (b) underextended, more than 1 mm short of the radiographic apex; and (c) overextended beyond the radiographic apex. In group 1 (nonflared), 32.3% of the root canals were classified in category a, as compared with 75.0% in group 2 (preflared). Over 26% of the root canals in group 1 and approximately 4% of the canals in group 2 were included in category b. Files inserted in preflared root canals had a significantly lower incidence of overextension than those placed in nonflared canals (21% versus 41%). The ability to determine the apical constriction by tactile sensation was significantly increased when the canals were preflared (p < 0.0001).

Adult↗

PubMed1995

Investigation of mineral trioxide aggregate for root-end filling in dogs.

Numerous compounds have been used as root-end filling materials. Based on the results of in vitro and intraosseous implantation tests, mineral trioxide aggregate (MTA) seems to have potential as a root-end filling material. The purpose of this study was to examine the periradicular tissue response of dogs to MTA and amalgam. Lesions were developed in periradicular tissues of 46 roots in six beagle dogs. The canals on half of the roots were instrumented and obturated with gutta-percha and sealer, and their access cavities were sealed with MTA. The remaining root canals were instrumented and obturated with gutta-percha and sealer, and their access cavities were sealed with MTA. The remaining root canals were instrumented and obturated with gutta-percha without root canal sealer. The access cavities of the teeth in this group were left open to the oral cavity. After surgical resection of roots, half of the root-end cavities were filled with amalgam and the rest with MTA. The periradicular tissue response of the dogs was evaluated histologically 2 to 5 and 10 to 18 wk following periradicular surgery. Statistical analysis of the results showed less periradicular inflammation and more fibrous capsules adjacent to MTA, compared with amalgam. In addition, the presence of cementum on the surface of MTA was a frequent finding. The results show that MTA can be used as a root-end filling material.

Aluminum Compounds↗

PubMed1995

Effects of ultrasonic root-end cavity preparation on the root apex.

This study determined the effect of bur and ultrasonic preparation on the root apex. After cleaning, shaping, and obturation of root canals of 47 single-rooted teeth and resection of their apexes were done, 24 root-end cavities were prepared with a bur, and the rest were prepared with ultrasonic tips attached to two different ultrasonic units. After photographs of the prepared root ends were taken, their resin replicas were prepared and examined with a scanning electron microscope. Photographs and scanning electron microscope photomicrographs were examined for the presence or absence of cracks. The results showed a significantly higher incidence of crack formation in the walls of root-end cavities prepared by ultrasonic tips compared with those made by the bur.

Analysis of Variance↗

PubMed1995

Use of mineral trioxide aggregate for repair of furcal perforations.

The histologic response to intentional perforation in the furcations of 28 mandibular premolars in seven dogs was investigated. In half the teeth, the perforations were repaired immediately with either amalgam or mineral trioxide aggregate; in the rest the perforations were left open to salivary contamination before repair. All repaired perforations were left for 4 months before histologic examination of vertical sections through the site. In the immediately repaired group, all the amalgam specimens were associated with inflammation, whereas only one of six with mineral trioxide aggregate was; further, the five noninflamed mineral trioxide aggregate specimens had some cementum over the repair material. In the delayed group, all the amalgam specimens were associated with inflammation; in contrast only four of seven filled with the aggregate were inflamed. On the basis of these results, it appears that mineral trioxide aggregate is a far more suitable material than amalgam for perforation repair, particularly when used immediately after perforation.

Aluminum Compounds↗

PubMed1994

Mediators of acute and chronic periradicular lesions.

Multiple mechanisms are involved in the pathologic changes associated with formation of acute and chronic periradicular lesions. Mechanical injury to the periradicular tissues can cause activation of several pathways of inflammation and release of nonspecific mediators. Continuous irritation of periradicular tissues can cause activation of several pathways of inflammation and release of nonspecific mediators. Continuous egress of antigens from a pathologically involved root canal can also result in one or a combination of the various types of immunologic reactions. A number of these reactions participate in the destruction of periradicular tissues. Because of complex interactions between the various components of these systems, the dominance of any one pathway or substance may be difficult to establish.

Animals↗

PubMed1994

Passive step-back technique.

Several techniques have been advocated to clean and shape pathologically involved root canal systems. Studies have shown that most of these techniques transport the original shape of the apical portion of the root canals. This article describes a step-by-step method, Passive Step Back Technique, which uses a combination of hand and rotary instruments to clean and shape root canals.

Humans↗

PubMed1994

Passive step-back technique. A sequential use of ultrasonic and hand instruments.

Step back, step down, crown down, balanced forces techniques and their variations have been proposed to clean and shape the root canal systems. Ultrasonic instruments have also been used to clean and shape pathologically involved root canals. Because neither of these techniques alone can completely clean complex root canal systems, a step-by-step sequential use of ultrasonic and hand instruments that uses the advantages of both techniques and eliminates most of their disadvantages is described in this article. Proper use of this technique produces cleaner canals and less transportation of root canals, reduces procedural accidents, and is convenient for the operator as well as the patient.

Humans↗

PubMed1994

Effectiveness of various medications on postoperative pain following root canal obturation.

This prospective study compared the effectiveness of nine medications and a placebo in controlling pain following obturation. A total of 588 patients who required root canal obturation were included. After obturation of root canals, each patient took one of the medications, salicylic acid (2 x 250 mg), acetaminophen (2 x 250 mg), ibuprofen (2 x 250 mg), ketoprofen (2 x 250 mg), acetaminophen (2 x 250 mg) plus codeine (2 x 250 mg), penicillin (2 x 250 mg), erythromycin base (2 x 250 mg), penicillin plus ibuprofen (2 x 250 mg), methylprednisolone (2 x 250 mg) plus penicillin (2 x 250 mg), or a placebo, every 6 h for 72 h. All medications were encapsulated in identical capsules. The patients registered their degree of discomfort on a visual analogue scale of 0 to 9. Statistical analysis of the data showed that the incidence of postoperative pain after obturation is lower than that following complete cleaning and shaping (5.83% versus 21.76%). In addition, there was no significant difference between the effectiveness of the various medications and placebo tablets in controlling postoperative pain following obturation.

Acetaminophen↗

PubMed1994

Effectiveness of various medications on postoperative pain following complete instrumentation.

The root canals of 588 consecutive nonsurgical patients with varying levels of pain were completely instrumented in 10 endodontic practices and 4 endodontic graduate programs. The participants were sequentially assigned to one of nine medications and a placebo. The severity of pain was assessed by the visual analog scale for 72 h following instrumentation. Among all of the parameters studied, three factors (preoperative pain, apprehension, and types of medication) were found to be significant in determining postinstrumentation pain. An association was found between the intensity of pre-and postoperative pain. As the intensity of preoperative pain increased, the chances for more severe postoperative pain increased (p < 0.0001). In addition, an association between the presence of apprehension before any treatment and postoperative pain was also noted (between 0.012 < p < 0.047). Examination of the time-effect curves for various medications in patients with no mild pain showed no statistical significant difference between the effectiveness of different medications and placebo. However, a multiple comparison of the effectiveness of various medications and placebo on patients in moderate and severe preoperative pain showed that ibuprofen, ketoprofen, erythromycin base, penicillin, and methylprednisolone plus penicillin were more effective than placebo within the first 48 h following complete instrumentation.

Acetaminophen↗