Biomedical subjects

M Torabinejad

Publications and source records attributed to M Torabinejad.

At least 55 records · Page 3Linked to original sources

PubMed1994

Interleukin 1-beta in symptomatic and asymptomatic human periradicular lesions.

Interleukin 1 beta (IL-1 beta) has been shown to be a potent mediator of bone resorption and has been implicated in resorption in periradicular lesions. In this study we compared the local concentrations of IL-1 beta in symptomatic and asymptomatic human periradicular lesions. Periradicular tissues from patients with symptomatic and asymptomatic lesions were obtained and stored at -70 degrees C. Pulpal tissues from unerupted third molars and chronically inflamed gingival tissues were also obtained and used as negative and positive controls, respectively. Tissue samples were homogenized, and supernatants were assayed for IL-1 beta by the enzyme-linked immunosorbant assay. Significantly higher levels of IL-1 beta were found in symptomatic and asymptomatic lesions and inflamed gingival tissues compared with uninflamed pulp tissues. There was a trend toward higher levels of IL-1 beta in symptomatic lesions compared with asymptomatic lesions, but the difference was not significant. The results suggest that IL-1 beta may play a significant role in the pathogenesis of human periradicular lesions.

Analysis of Variance↗

PubMed1994

Polymerase chain reaction detection of human immunodeficiency virus DNA in human periradicular lesions.

Human immunodeficiency virus (HIV) has been previously reported to be present in the dental pulp of a patient with AIDS. The present report investigated the feasibility of polymerase chain reaction (PCR) amplification to detect the HIV proviral DNA in cells from periradicular lesions from an HIV-positive patient. The standard PCR amplification with 30 cycles and the nested PCR consisting of two 25-cycle amplifications were used. Samples from each reaction were separated by nondenaturing polyacrylamide gel electrophoresis and stained with ethidium bromide for visualization. Gels were electroblotted to nylon membranes, which were then fixed, denatured, and dried. Membranes were hybridized to specific radioactive oligonucleotide probes and placed next to Kodak XAR film for visualization of the HIV-specific bands. No evidence of HIV-specific reaction was observed in cells (negative control) or in two periradicular lesions from two HIV-negative patients. The ethidium bromide strains revealed that PCR amplification of DNA extracts from two lesions from the HIV-positive patient yielded PCR bands (with both primer pairs) which corresponded to HIV-specific bands of the expected size.

Adult↗

PubMed1994

Apical marginal adaptation of orthograde and retrograde root end fillings: a dye leakage and scanning electron microscopic study.

A few studies have attempted to examine the correlation between clinical success of root canal therapy and in vitro examinations. In this case report we examined the apical adaptation of three orthograde fillings and four retrograde amalgam root end fillings from four radiographically successful teeth and one unsuccessful case by using dye leakage and scanning electron microscopic methods. Despite the radiographic appearance of successful root canal therapy, these examinations showed penetration of methylene blue dye through the apical foramina to the levels of the root canal filling materials in the roots treated nonsurgically and the presence of small gaps between filling materials and the dentinal walls. The methylene blue dye also penetrated through the interface between amalgam and root end cavities, and there were varying size gaps between the root end cavities and amalgam. Similar examinations on the radiographically unsuccessful retrograde filling showed the presence of gaps between the amalgam and the root end cavity preparation and complete penetration of methylene blue dye between amalgam, root canal filling materials, and the dentinal walls.

Aged↗

PubMed1994

Dye leakage of four root end filling materials: effects of blood contamination.

The purpose of this study was to compare the amount of dye leakage (in the presence versus absence of blood) in root end cavities filled with amalgam, Super EBA, IRM, and a mineral trioxide aggregate. After removing the anatomical crowns of 90 extracted human teeth, their roots were instrumented and obturated. Except for their apical 2 mm, the root surfaces were sealed with nail polish. After removal of the apical 2 to 3 mm of each root, a standardized root end cavity was prepared. Five root ends were filled with gutta-percha and no sealer, and another five root ends were filled with sticky wax. These served as positive and negative controls, respectively. The remaining 80 roots were divided into four equal groups and filled with the test materials. For each material, half of the root end cavities were dried prior to placing the filling material. The remaining half were filled after they were contaminated with blood. All 90 roots were then immediately placed in 1% methylene blue dye for 72 h. Finally, the roots were split and linear dye penetration was measured and statistically analyzed (analysis of variance). Presence or absence of blood had no significant effect on the amount of dye leakage. However, the results showed that there was a significant leakage difference between the root end filling materials (p < 0.0001). Mineral trioxide aggregate leaked significantly less than other materials tested with or without blood contamination of the root end cavities.

Aluminum Compounds↗

PubMed1994

A comparison between two root end preparation techniques in human cadavers.

The purpose of this study was to compare ultrasonic and bur root end cavity preparations with regard to retention, cleanliness, and root canal parallelism. Twenty anterior teeth from human cadavers were instrumented and obturated with gutta-percha and sealer. After raising a full-thickness flap, the apices of the roots were exposed and beveled at a 45-degree angle. Half of the apical cavities were prepared with an appropriate sized Carr alloy tip energized by an Amadent Ultrasonic unit. The other half was prepared with an inverted cone bur in a slow-speed handpiece. The teeth were then extracted, sectioned longitudinally, photographed, and scanning electron micrographs examined. The ultrasonic cavities produced more parallel walls and deeper depths for retention. In addition, the ultrasonic tips followed the direction of the canals more closely than those prepared by burs. Scanning electron microscopic examination of the cavity wall showed presence of cleaner surfaces of root end cavities prepared by ultrasonic tips than those made with burs.

Apicoectomy↗

PubMed1994

Presence of secretory IgA in human periapical lesions.

The concentration of secretory IgA in fluids present in the canals of 33 teeth was determined by the rocket immunoelectrophoresis technique. Except for the presence or absence of communication between the oral cavity and the root canals of the affected teeth, no other clinical finding showed significant statistical correlation with the presence of secretory IgA. The canals which were open to the oral flora had significantly higher concentrations of secretory IgA. Leaving canals open to the oral cavity may result in formation of periapical cysts.

Adolescent↗

PubMed1994

Detection of leukotriene C4 in human periradicular lesions.

The purpose of this study was to determine the concentration of leukotriene C4 (LTC4), a potent inflammatory mediator, in human symptomatic and asymptomatic periradicular lesions. Periradicular lesions from each of six asymptomatic and symptomatic patients were obtained. Six pulps from unerupted third molars served as the negative controls, six samples of chronically inflamed gingival tissues served as the positive controls. All samples were immediately frozen in liquid nitrogen. The concentration of LTC4 was determined by reverse-phase high-pressure liquid chromatography. Representative samples from each group were fixed in formalin, sectioned and stained with haemotoxylin and eosin. The concentrations of LTC4 found in the periradicular lesions were significantly higher than those in uninflamed pulpal tissue (P = 0.027). However, no statistically significant difference was found between the concentration of LTC4 in the periradicular lesions of the symptomatic patients and those found in the asymptomatic patients and in the samples of the chronically inflamed gingival tissue (P > 0.05). This data would suggest that among other inflammatory mediators, LTC4 participates in the pathogenesis of human periradicular lesions.

Analysis of Variance↗

PubMed1994

The effect of storage time on the degree of dye leakage of root-end filling materials.

The quality of the apical seal obtained by root-end filling materials generally has been assessed by the extent of dye penetration. Most investigators have allowed the root-end filling materials to set before they are tested. The purpose of this study was to evaluate if storage time had any influence on the amount of dye leakage. Seventy extracted single rooted human anterior teeth were used. After removal of their anatomical crowns, the roots were instrumented, filled with gutta-percha and Roth's sealer, and subjected to test conditions. The roots were coated with two coats of nail polish. Root ends were resected and class I cavities prepared. Sixty class I root-end cavities were filled with with either amalgam, super EBA, or IRM (20 each). Ten roots in each group were placed immediately into India ink for 48 h, the other 10 were stored for 24 h before placement into the ink. Ten roots (five per group) were used as positive (gutta-percha, no sealer) and negative (bone wax) controls. The roots were then demineralized, linear dye leakage was measured, and the data were evaluated statistically using ANOVA. Super EBA, and IRM showed significantly less dye leakage than amalgam (P < 0.0001). No significant difference existed between Super EBA and IRM. Storage time had no significant influence on the amount of dye leakage observed in this study.

Analysis of Variance↗

PubMed1993

Scanning electron microscopy and thermal characteristics of dentin ablated by a short-pulse XeCl excimer laser.

The interaction of a short pulse XeCl excimer laser radiation with human dentin was investigated. The dependence of surface temperatures and temperature gradients into the treated teeth on laser parameters such as fluence (0.5J/cm2-7J/cm2), pulse repetition rate (1Hz-35Hz), and spot size (0.004cm2-0.12cm2) was studied. Additionally, the effect of fluence and pulse repetition rate on dentin microstructure was studied using scanning electron microscopy (SEM). It is demonstrated that this "cold ablation" excimer laser can result in significant thermal modification in the dentin surfaces. Changes include the formation of melted dentin grains, which uniformly cover the surface and the exposed dentin tubules. Maximum temperatures of the ablated surfaces, however, remained relatively low at most laser parameters used. Also, the immediate neighborhood of the root canal was essentially undisturbed at most laser parameters. These observations suggest that with the appropriate choice of parameters XeCl lasers can be effective in producing surface structures that may prove useful in enhancing bond strength or other applications in dentistry, without exposing tooth pulp to significant temperature elevation.

Absorption↗

PubMed1993

Role of T cells in the pathogenesis of periapical lesions. A preliminary report.

The pulps of mandibular molars of 15 athymic and 15 conventional rats were surgically exposed and left open to their oral flora. Each group was divided into three subgroups of five animals each. The rats were killed after their pulps were exposed for 2, 4, or 8 weeks. After fixing, decalcifying, and embedding, the specimens were sectioned and stained with hemotoxylin and eosin. They were then examined under a microscopic grid and quantified by percentages of surface areas of bone, connective tissue, bone marrow, intrabony spaces, periapical lesions, and numbers of osteoclasts, with the use of a DataVoice computerized data collection and analysis system. Statistical analysis showed no significant difference between periapical tissue responses of the conventional and athymic groups. The results indicate that the pathogenesis of periapical lesions is a multifactorial phenomenon and is not totally dependent on the presence of T-cell lymphocytes.

Analysis of Variance↗

PubMed1993

Electron microscopic changes in human pulps after intraligamental injection.

Because of its advantages, intraligamental injection is becoming a popular anesthetic technique to achieve anesthesia in vital pulps. This study investigated the possible effects of intraligamental injection on human pulps under electron microscope. Forty-two mandibular and maxillary premolars were scheduled to be extracted for orthodontic reasons after being anesthetized with intraligamental injections of 2% lidocaine, 1:100,000 epinephrine (experimental group). The same anesthetic solution was used on the contralateral teeth with either nerve or field blocks (control group). To examine the effects of ischemia on odontoblasts, 12 anesthetized premolars were extracted, and their pulps were placed in physiologic saline solution for different time intervals (15 minutes to 6 hours). The teeth in the experimental and control groups were then reanesthetized with nerve or field blocks of 3% carbocaine without epinephrine after time periods that ranged from 15 minutes to 28 days. After extraction, the teeth were sectioned vertically and their pulps were fixed in 3% glutaraldehyde. The odontoblastic layer of each pulp was examined under electronic microscope. Nuclear and cytoplasmic changes started an hour after ischemia in the pulps placed in physiologic saline. In contrast, little or no cellular changes occurred in pulps of the experimental or controls groups. On the basis of the results, it appears that intraligamental injection has no long-term deleterious effects on pulps of young human premolars.

Anesthesia, Dental↗

PubMed1993

Effect of ArF-193 nm excimer laser on human dentinal tubules. A scanning electron microscopic study.

The purpose of this study was to evaluate the effects of the ArF-193 nm excimer laser on the dentinal tubules of extracted human teeth under a scanning electron microscope. Fifteen 3 mm thick slices were cut with an electric saw at the cementoenamel junction from 15 extracted human teeth. A diamond bur was used to remove the cementum layer and expose the dentinal tubules. Each slice was scored by a permanent marker into four equal quadrants. The ArF excimer laser was applied for 5 seconds on three of the quadrants with fluences that ranged from 0.2 J/cm2 to 15 J/cm2 and pulse repetition of 25 Hz. The untouched quadrant served as a control. The specimens were mounted on stubs, sputter coated by gold, and examined by a scanning electron microscope. The effects of the ArF excimer laser irradiation varied. Laser fluences of 0.2, 0.5, and 1.0 J/cm2 had no effect. Although fluence of 15 J/cm2 caused significant removal of peritubular dentin, melting and resolidification of the dentinal smear layer was also observed under the scanning electron microscope with a laser fluence of 5 J/cm2.

Argon↗

PubMed1993

Sealing ability of a mineral trioxide aggregate when used as a root end filling material.

This in vitro study used rhodamine B fluorescent dye and a confocal microscope to evaluate the sealing ability of amalgam, super EBA, and a mineral trioxide aggregate when used as root end filling materials. Thirty single-canal teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. After application of nail polish to the external surface, the apical 3 mm of each root was resected and 3-mm deep root end preparations were made. The roots were randomly divided into three groups and the root end preparations filled with the experimental materials. All roots were then exposed to an aqueous solution of rhodamine B fluorescent dye for 24 h, longitudinally sectioned, and the extent of dye penetration measured using a confocal microscope. Statistical analysis showed that the mineral trioxide aggregate leaked significantly less than amalgam and super EBA.

Aluminum Compounds↗

PubMed1993

Sealing of human dentinal tubules by XeCl 308-nm excimer laser.

Root hypersensitivity occurs as a result of exposed dentinal tubules. Various methods and materials have been tried in an attempt to occlude these tubules. The purpose of this investigation was to study by scanning electron microscope the effects of XeCl excimer laser on exposed dentinal tubules of human extracted teeth. Fifteen 3-mm-thick slices were cut at the cementoenamel junction from 15 extracted human teeth by an electric saw. By using a diamond bur to remove the cementum layer the dentinal tubules were exposed. Each slice was scored by a permanent marker into four equal quadrants. Three of the quadrants were lased for 4 s by XeCl excimer laser with fluences ranging from 0.5 to 7.0 J/cm2 and pulse repetition of 25 Hz. The unlased quadrant served as control. The specimens were mounted on a stub, sputter coated by gold, and examined by scanning electron microscope. Nonlased surfaces showed numerous exposed dentinal tubules. In contrast, all specimens lased at fluences of up to 1 J/cm2 showed the presence of melted dentin which closed the dentinal tubules. At fluences of 4 J/cm2 and higher, rupture of molten materials and exposure of dentinal tubules were noted. The results indicate the application of XeCl excimer laser at specific fluences can cause melting of dentin and closure of exposed dentinal tubules.

Dentin↗

PubMed1993

Human saliva penetration of coronally unsealed obturated root canals.

Studies have shown significant coronal dye and bacterial leakage following exposure of sealed root canals to artificial and natural saliva. The purpose of this study was to determine the time needed for bacteria in natural saliva to contaminate the entire length of root canals obturated by lateral and vertical condensation techniques. Forty root canals were cleaned and shaped using a step-back technique. Thirty root canals were obturated with gutta-percha and root canal sealer using either lateral or vertical condensation techniques. Forty root canals were obturated without a root canal sealer and served as positive controls. After obturation, the coronal 3 mm of five root canals were sealed with sticky wax and served as negative controls. The coronal portions of the filling materials were placed in contact with human saliva and the number of days required for bacteria in saliva to penetrate the entire root canals were determined. No bacterial leakage occurred in the negative control group. Complete bacterial leakage occurred within 2 days in the positive control group. All root canals were recontaminated in less than 30 days. No statistical significant difference was found between the two methods of obturation.

Dental Leakage↗

PubMed1993

An in vivo evaluation of Endex electronic apex locator.

Because of technical problems and hazards of radiation, dentists have desired alternative ways to determine the working length during root canal therapy. Attention has turned to electronic devices for measuring root canal length. Several such devices are now available. They show promise but their accuracy is hampered because moisture in the root canal can result in inaccurate responses. Recently, a new device, Endex, has been introduced, claiming ease of operation and accuracy in moist environments. Ten operators used the Endex to measure 185 root canal lengths (in 99 teeth). Endex measurements were compared with radiographic measurements. The Endex located the apical constriction accurately within +/- 0.5 mm in 89.64% of moist canals.

Adolescent↗

PubMed1993

Sealing ability of a mineral trioxide aggregate for repair of lateral root perforations.

Amalgam, IRM, and a mineral trioxide aggregate were tested for repair of experimentally created root perforations. Fifty sound, extracted mandibular and maxillary molars were used in this study. A perforation was created on the mesial root surface at about a 45-degree angle to the long axis of each tooth. The tooth was then placed into a saline-soaked "Oasis" to simulate a clinical condition. After placing the repair materials into the perforations, the teeth were kept for 4 wk in the Oasis model. The perforation sites were then stained with methylene blue for 48 h, sectioned, and examined under a dissecting microscope. The results showed that the mineral trioxide aggregate had significantly less leakage than IRM or amalgam (p < 0.05). The mineral trioxide aggregate also showed the least overfilling tendency while IRM showed the least underfilling tendency.

Aluminum Compounds↗

PubMed1993

Effects of the XeCl excimer laser on Streptococcus mutans.

The effect of XeCl excimer laser irradiation on the growth of Streptococcus mutans in liquid media and on agar plates was studied. Bacterial suspensions of S. mutans were placed in 96 wells of well culture plates. The contents of 72 wells (three experimental groups of 24 wells each) were lased for different time durations (2, 4, and 8 s). The remaining 24 wells were left unlased to be used as controls. Samples were withdrawn from all wells and examined for surviving bacteria. In addition, blood agar plates were inoculated with S. mutans and were lased with different energy densities (fluences). Zones of bacterial inhibition were measured. Analysis of variance test was used to determine statistical differences. The bactericidal effect of the laser applications was directly related to the amount of radiation time. Laser irradiation for 4 and 8 s resulted in bactericidal effect that was statistically significant compared with no treatment or to 2-s exposure. The effect of different energy levels was studied by irradiating inoculated blood agar plates. The zones of inhibition produced by higher energy levels (0.5 J/cm2, 0.7 J/cm2, and 1.0 J/cm2) were larger in comparison to the lowest fluence used (0.1 J/cm2). Application of the laser to the surface of the agar plates produced an indentation with a surrounding halo. The indentations and the zones of inhibition were more pronounced as the fluences increased. Based on our results it appears that the XeCl 308-nm excimer laser can kill S. mutans. This effect should be tested on other bacteria commonly present infected root canals.

Analysis of Variance↗