Microcomputed tomographic evaluation of mandibular molars with single distal canals.

The aim of this study was to evaluate, using microcomputed tomography (µCT), the frequency of conjoined mesial canals in first and second mandibular molars with a single distal canal. Mandibular first (n = 114) and second molars (n = 114) with mature apices were randomly selected from a pool of extracted teeth. The specimens were decoronated to establish clinically the existence of a single distal canal. Teeth with C-shaped canals were discarded. Each tooth was scanned with a µCT system and evaluated in 3 dimensions. Of 228 examined teeth, 206 were included in the study. Of these, 129 (62.6%) displayed conjoined mesial canals with a single portal of exit, and 77 (37.4%) displayed 2 distinct mesial canals with 2 separate portals of exit. Of the teeth with conjoined mesial canals, 71 (55.0%) were second molars and 58 (45.0%) were first molars. Conjoined mesial canals exhibited a mean interorifice distance of less than 3.00 mm. These data regarding morphological patterns alert clinicians to the possible need to modify endodontic techniques in mandibular molars with single distal canals.

Real time workload classification from an ambulatory wireless EEG system using hybrid EEG electrodes.

This paper describes a compact, lightweight and ultra-low power ambulatory wireless EEG system based upon QUASAR's innovative noninvasive bioelectric sensor technologies. The sensors operate through hair without skin preparation or conductive gels. Mechanical isolation built into the harness permits the recording of high quality EEG data during ambulation. Advanced algorithms developed for this system permit real time classification of workload during subject motion. Measurements made using the EEG system during ambulation are presented, including results for real time classification of subject workload.

Effect of ProRoot MTA mixed with chlorhexidine on apoptosis and cell cycle of fibroblasts and macrophages in vitro.

AIM: To compare the percentage of apoptotic cells and the cell cycle profile of fibroblasts and macrophages exposed to either ProRoot mineral trioxide aggregate (MTA) mixed with chlorhexidine (CHX), or exposed to ProRoot MTA mixed with sterile water. METHODOLOGY: Mouse gingival fibroblasts or mouse macrophages were seeded in six-well plates and allowed to attach overnight. Freshly mixed or set (allowed to dry for 24 h) specimens of tooth-coloured (white) ProRoot MTA were prepared with 0.12% CHX gluconate (MTA/CHX) or with sterile water (MTA/H2O). The cells were exposed for 24 h to the MTA specimens, which were placed over permeable membrane inserts to avoid direct contact with the cells. Untreated cells served as controls. Propidium iodide staining followed by flow cytometry was used to evaluate the effects of ProRoot MTA on cell apoptosis and cell cycle. Statistical analyses were performed by one-way anova followed by post-hoc tests with the use of the SigmaStat 2.0 software, and significance was determined at P < or = 0.05. RESULTS: MTA specimens containing CHX induced apoptosis of macrophages and fibroblasts (P < 0.05). In contrast, no change in the proportion of apoptotic cells was observed when sterile water was used to prepare the specimens (P > 0.05). Cell cycle analysis showed that exposure to MTA/CHX decreased the percentage of fibroblasts and macrophages in S phase (DNA synthesis) as compared with exposure to MTA/H2O (P < 0.05). CONCLUSION: This in vitro study demonstrated that the substitution of CHX for sterile water in MTA increases its cytotoxicity. This suggests that the potentially beneficial antimicrobial effect of CHX may be accompanied by an increase in the cytotoxicity of the resulting MTA-based material.

Apical extrusion of thermoplasticized obturating material in canals instrumented with Profile 0.06 or Profile GT.

The purpose of this in vitro study was to compare the extrusion of thermoplacticized gutta-percha in teeth instrumented with Profile 0.06 or Profile GT, and obturated with Thermafil Plus and Thermafil GT, respectively. A total of 120, extracted, human maxillary central incisors were divided into four equal groups. Group 1 was instrumented with Profile 0.06 and obturated with Thermafil Plus. Group 2 was instrumented with Profile 0.06 and obturated using warm vertical condensation (negative control). Group 3 was instrumented with Profile GT and obturated with Thermafil GT. Group 4 was instrumented with Profile GT and obturated like Group 2 (negative control). Extrusion was graded as present or absent. Results found 9 of 30 extruded for group 1, 1 of 30 for group 2, 15 of 30 for group 3, and 2 of 30 for group 4. The results suggest that, in vitro, Thermafil GT may be more prone to extruding gutta-percha past the apical foramen than Thermafil Plus.

Anticholinergic therapy for chronic asthma in children over two years of age.

BACKGROUND: In the intrinsic system of controlling airway calibre, the cholinergic (muscarinic) sympathetic nervous system has an important role. Anticholinergic, anti muscarinic bronchodilators such as ipratropium bromide are frequently used in the management of childhood airway disease. In asthma, ipratropium is a less potent bronchodilator than beta-2 adrenergic agents but it is known to be a useful adjunct to other therapies, particularly in status asthmaticus. What remains unclear is the role of anticholinergic drugs in the maintenance treatment of chronic asthma. OBJECTIVES: To determine the effectiveness of anticholinergic drugs in chronic asthma in children over the age of 2 years. SEARCH STRATEGY: The Cochrane Airways Group trials register and reference lists of articles were searched in January 2002. SELECTION CRITERIA: Randomised controlled trials in which anticholinergic drugs were given for chronic asthma in children over 2 years of age were included. Studies including comparison of: anticholinergics with placebo, and anticholinergics with any other drug were included. DATA COLLECTION AND ANALYSIS: Eligibility for inclusion and quality of trials were assessed independently by two reviewers. MAIN RESULTS: Eight studies met the inclusion criteria.Three papers compared the effects of anticholinergic drugs with placebo, and a meta-analysis of these results demonstrated no statistically significant benefit of the use of anticholinergic drugs over placebo in any of the outcome measures used. The results of one of these trials could not be included in the meta-analysis but the authors did report significantly lower symptom scores with inhaled anticholinergics compared with placebo. However, there was no significant difference between ipratropium bromide and placebo in the percentage of symptom-free nights or days. Two trials studied the effects of anticholinergics on bronchial hyper responsiveness to histamine, by measuring the provocation dose of histamine needed to cause a fall of 20 % in FEV1 (PD 20). One study (comparing anticholinergics with placebo) reported a statistically significant increase in PD 20 but this was not found in another study (comparing anticholinergics with a beta-2 agonist). Both trials also examined the effect of anticholinergic drugs on diurnal variation in peak expiratory flow rate (PEFR) and reported no significant effect. Two studies compared the addition of an anticholinergic drug to a beta-2 agonist with the beta-2 agonist alone. Both trials failed to show any significant benefit from the long term use of combined anticholinergics with beta-2 agonists compared with beta-2 agonists alone. One trial compared the effects of oral and inhaled anticholinergic drugs with placebo. No statistically significant differences were found in any of the outcome measures except for a higher FEV1 / VC ratio and RV / TLC ratio with oral anticholinergic therapy when compared with placebo. REVIEWER'S CONCLUSIONS: The present review summarises the best evidence available to date. Although there were some small beneficial findings in favour of anticholinergic therapy, there is insufficient data to support the use of anticholinergic drugs in the maintenance treatment of chronic asthma in children.

Evaluating IL-2 levels in human pulp tissue.

In murine and human CD4+ T cell populations, there are three subpopulations of T helper cell types. Hahn et al. demonstrated the ratio of CD4/ CD8 + cells significantly increases in inflamed dental pulps compared with normal pulps. Elevated levels of interleukin (IL)-2 have been detected in inflamed dental pulps and the level of IL-2 could be used as a marker for inflammation. In this study, levels of IL-2 were evaluated by using a human IL-2 cytokine assay kit on 80 samples of freshly extracted human pulp tissue. Applying standard diagnostic procedures, the tissue samples were clinically categorized into one of three experimental groups. The results demonstrated that there were no significant differences between the concentrations of IL-2 in any of the experimental groups. Our findings are different from results reported previously. Further investigation is warranted to determine if a correlation exists between the concentration of IL-2 or other interleukins and the degree of inflammation present in the dental pulp.

Canal-centering ability of two rotary file systems.

The ability of two nickel-titanium rotary file systems to maintain the original path of the canal were compared by using a new split-mold design (the Endodontic Cube). The mesial roots of 10 mandibular first- and second-molar teeth with separate canals from orifice to foramen were divided into two groups based on canal curvature and morphology. Working lengths for each canal were determined 1.0 mm short of where the file tip was visible on the external surface of the root. The teeth were embedded in composite resin by using the Endodontic Cube as a mold and sectioned into five pieces. ProFile Ni-Ti.06 taper Series 29 and ProFile GT rotary instrumentation techniques were randomly assigned to one of the canals and used in a crown-down fashion to a 0.217 ProFile and a 0.06 GT master apical file, respectively. Digital photographs were made of the middle three sections and software features of Adobe Photoshop were used to measure the movement of the canal centers by superimposing the images of the instrumented and uninstrumented canals. Data were analyzed using ANOVA. Both systems remained centered within the canal with minimal deviation from the original canal path. The largest mean movement was less than 0.15 mm. The Endodontic Cube was an effective tool for studying and comparing instrumentation techniques.

In vitro infrared thermographic assessment of root surface temperatures generated by the thermafil plus system.

The purpose of this in vitro study was to investigate root surface temperatures generated by the Thermafil Plus system using infrared thermography. A total of 60 extracted human maxillary central incisors and maxillary first molars were biomechanically instrumented using ProFile 0.04 Taper Series 29 rotary instruments. The root canals were obturated using the Thermafil Plus system. An infrared thermography camera was used to measure the external root surface temperatures during and after the completion of obturation. The mean temperature rise of the external root surface from the ambient temperature was 4.26 degrees C for the mesial buccal roots, 4.58 degrees C for the distobuccal roots, 4.76 degrees C for the palatal roots, and 4.87 degrees C for the anterior roots. These temperatures were well below the critical level of 10 degrees C needed to cause damage to the attachment apparatus. From this in vitro experiment, no evidence was discovered which would indicate that the Thermafil Plus obturation system would result in damage to the periodontal ligament and the surrounding attachment apparatus as a consequence of temperature rise on the external root surface.

The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study.

AIM: The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth. METHODOLOGY: Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C-E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan's Multiple Range Test were used to compare Groups A-F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences. RESULTS: Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method. CONCLUSIONS: Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals.

Development of a direct weighting procedure for quality of life domains.

The Schedule for the Evaluation of Individual Quality of Life allows individuals to nominate the domains they consider most important to their quality of life and to use their own value system when describing the functional status and relative importance of those domains. The weights for domain importance are derived through a procedure called judgement analysis. As judgement analysis is impractical for individuals with cognitive impairment and in many clinical situations, a shorter, direct weighting procedure has been developed. To test the new procedure, 40 healthy individuals completed both direct and judgement analysis weightings, at t1 and 7-10 days later (t2). After a further 7-10 days (t3), they were asked to identify the weight profiles they had previously produced using each method. The weights produced by the two methods differed on average by 7.8 points at t1 and 7.2 points at t2. The direct weights changed on average by 4.5 points from t1 to t2, while the judgement analysis weights changed by 8.4 points. At t2, 55% of individuals were able to identify the direct weights they had previously produced. The new procedure demonstrates stability and validity but is not interchangeable with judgement analysis. The most appropriate ways of using and interpreting both procedures are discussed.

Comparison of radiographic and electronic working lengths.

The purpose of this study was to compare the ability of radiographic and electronic methods to determine reliably the location of the apical constriction. The working length of root canals in human cadaver teeth was determined by positioning an endodontic file at the apical termination point as indicated by an apex locator. These same teeth were radiographed at various angles with the file in place. The radiographs were evaluated by five examiners to determine a radiographic termination point for each canal. Teeth were extracted and examined histologically to determine the ideal termination point. The deviations of the two experimental termination points from the ideal termination point were compared. The mean of the absolute value of the deviations from the apical constriction for the apex locator was significantly less (p < 0.05) than that for the radiographic method. Thus, the method using the apex locator was slightly more reliable.

The treatment of postanaesthetic shivering: a double blind comparison between alfentanil and pethidine.

It has been postulated that pethidine may mediate its effects on postanaesthetic shivering (PAS) via kappa-opioid receptors. However, clinical evidence indicates that alfentanil, a pure mu-agonist, may also have beneficial effects on PAS. In order to assess whether opioid effects on PAS are effected via kappa receptors, fifty-one patients were randomised to receive alfentanil 250 micrograms (n = 18), pethidine 25 mg (n = 18) or placebo (n = 15) on a double-blind basis for the treatment of established postanaesthesia shivering (PAS). Both drugs proved significantly better in treating PAS than placebo (P < 0.005). Following treatment, blood pressure fell and oxygen saturation increased in patients in the two treatment groups when compared with the control group (P < 0.05). There was a highly significant incidence of reshivering in the alfentanil treated group (P < 0.005). In conclusion, the high incidence of reshivering indicates that alfentanil is unlikely to supercede pethidine in the treatment of PAS, but its initial success rate implies that pethidine's anti-shivering effect is unlikely to be mediated via kappa-opioid receptors.

Individual quality of life in the healthy elderly.

Quality of life research with the elderly has usually focused on the impact of decline in function, and used a pre-determined model of quality of life in old age. The Schedule for the Evaluation of Individual Quality of Life (SEIQoL) allows individuals to nominate, weigh and assess those domains of greatest relevance to their quality of life. The SEIQoL was administered to 56 healthy elderly community residents at baseline and 12 months later. Quality of life levels were significantly higher at baseline (t = -2.04; p = 0.04) than that of a previously studied sample of healthy adults below 65 years of age, and did not change significantly over the study period. The domains nominated by both samples as relevant to their quality of life differed notably. Health status was not correlated with the perceived importance of health at baseline, and showed only a low correlation (r = 0.27) at 12 months. The weight placed on health did not increase over the study period despite a significant decline in health status. The value of allowing the individual to define personal quality of life values in a research context is explored.

Microleakage in facial and lingual Class 5 composite restorations: a comparison.

The purpose of this in vitro study was to determine if there is a difference in microleakage between facial and lingual enamel and cementum using two different evaluation techniques. Class 5 preparations were made in 50 teeth on the facial and lingual tooth surfaces and restored using dentin bonding and composite resin. The teeth were thermocycled, silver nitrate stained, and longitudinally sectioned into mesial and distal halves through each restoration. The mesial half was scored using a rank order system. A Kruskal-Wallis one-way ANOVA was performed. The distal half was scored by measurement, and a two-sample t-test was performed. There were no statistically significant differences (P > or = 0.05) in microleakage between facial and lingual tooth enamel or cementum surfaces using either measurement technique.

Microleakage of Class 5 composite resin restorations: a comparison between in vivo and in vitro.

The purpose of this study was to determine if a difference exists in microleakage between in vivo and in vitro class 5 composite resin restorations using two variations of a bonding resin (Universal Bond 2 and Universal Bond 3). Class 5 cavities were prepared in 24 matched pairs of teeth on the buccal and lingual surfaces. One tooth of each pair was prepared and restored in vivo and the other in vitro. After preparation and enamel etching, Universal Bond 2 was randomly applied to one surface of each tooth in the pair and Universal Bond 3 to the other surface. Composite resin (Prisma AP.H) was placed in each preparation, light cured, and finished using a standard technique. The in vivo samples were extracted approximately 6 weeks after placement of the restorations. The in vitro samples were thermocycled for 540 cycles (5 to 55 degrees C/1-minute dwell time). All teeth were stained with silver nitrate and longitudinally divided. The teeth were scored on a ranking system of 0 being no leakage to 4 being leakage to the pulpal wall of the preparation. A Wilcoxon matched pairs signed rank test was performed on the data (P < or = 0.05). There were no statistically significant differences in microleakage between restorations using Universal Bond 2 and Universal Bond 3. There were statistically significant differences when comparing the in vivo and in vitro restorations. More microleakage occurred in the in vitro restorations.

Cytotoxicity of retrofill materials.

Dentin bonding agents reduce microleakage and enhance marginal adaption of composite resin restorations. These characteristics are advantages for their use as an endodontic retrofilling material. Because these materials will be in direct contact with vital tissues, their cytotoxic potential must be evaluated before clinical use. It was the purpose of this study to evaluate the cell cytotoxicity of amalgam, Caulk Universal Bond, Gluma, 35% HEMA, Morita Clearfil, Scotchbond 2, Super EBA, Tenure, and Tenure 5-4. VERO cells were grown in RPMI-1640 medium and cell monolayers were prepared by incubating 15 ml of the cell suspension in 60-mm culture dishes at 37 degrees C in 5% CO2. Twelve milliliters of a medium-agarose mixture containing 1% neutral red vital stain were overlayed onto the cell layer and allowed to solidify. The materials were directly exposed to the agarose overlays by inverting 6.0-mm diameter polypropylene capsules containing the cured and liquid sample materials either immediately (0 time) or after placement in phosphate-buffered saline with 1% gentamicin for 7, 15, or 30 days. Cytotoxicity was determined by measuring the zone of killed cells around the sample 24 h after placement on the agarose. Cytotoxicity was determined by measuring the zones of cell inhibition at 24 h and at 7, 15, and 30 days. Initially, all of the materials were found to be cytotoxic, except amalgam and the Tenure components. The dentin bonding primers showed a mean zone of inhibition of 13.2 mm and the cleansers a 40.0-mm zone. Amalgam demonstrated increasing cytotoxicity: 0.0 mm at 24 h to 12.0 mm at 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sterilization on contaminated sponges.

Sponges are routinely used as a storage medium for endodontic files during clinical practice; however, very little research has been done to determine the effectiveness of sterilization procedures for these contaminated sponges. The purpose of this in vitro study was to determine the efficacy of chemical vapor sterilizers (chemiclaves), steam pressure sterilizers (autoclaves), and dry heat sterilizers on laboratory contaminated sponges. Four different types of sponges were used in this study: a black, relatively nonporous sponge; a red, semiporous stationary sponge; a blue, endodontic sponge, and a yellow, common household sponge. Natural sponges were eliminated from the study, because their large pore size made them unsuitable as a storage medium for endodontic instruments. The sponges were divided into three groups: chemiclave, autoclave, and dry heat. Five samples of each sponge type were impregnated with biological indicating strips containing spores of Bacillus stearothermophilus. Each sponge was subjected to 25 cycles of sterilization. The spore strip indicator was inserted into the sponges at 1, 5, 10, 15, 20, and 25 cycles. The spore strip was cultivated in trypticase soy broth medium solution at 55 +/- 1 degree C for 7 days. At 7 days the culture vials were read for turbidity; its presence indicating a positive culture. The samples that were subjected to chemiclaving demonstrated positive cultures of 0.00%, 0.00%, and 30.00% and those to autoclaving 3.33%, 0.00%, and 0.00% positive cultures for the black, red, and blue sponge types, respectively. None of the sponges survived dry heat sterilization. The O-Cell-O sponges become unusable when subjected to all of the sterilization methods used in this study.

The electronic determination of working length.

Electronic digital imaging systems provide the clinician with the ability to manipulate, enhance, and store radiographic images for immediate recall. Apex locators are a useful adjunct to endodontic therapy. It is important to understand that they do not replace radiographs completely in treatment. Radiographs still provide the only means by which the clinician can gain an overall visual image of the tooth being treated. It is important to visualize the crown and root anatomy; the relationship of the crown to the root; the size, shape, curvature, and location of the roots; and to estimate the tooth length. These data give the clinician a good guide and provide a baseline from which to use an apex locator. Failure to do this will result in errors of measurement due to a lack of basic treatment information. The current types of apex locators available are accurate for determining working length, providing some basic steps are followed carefully for their use. Current generation units have degrees of accuracy that range from 83.0% to 93.4%. They need to have well-charged batteries and to be calibrated correctly before use. Resistance-type apex locators require a reasonably dry canal--a guideline that must be strictly followed. Files must be matched to fit the canal snugly, contact against metallic restorations must be avoided, and good lip contact for the return electrode must be obtained. The impedance-type units require careful calibration before use, careful matching of the coated probe to the canal diameter, and good patient contact with the hand-held return electrode. Care must be taken to ensure that the insulating layer does not wear off the coated probes during use. The frequency-based units are easy to use. They operate in an electroconductive environment and have the advantage of using conventional K-type files. However, the rechargeable battery must be kept fully charged, and their calibration steps must be followed. Fluid filling the tooth to the level of the pulp chamber will cause the units to become overloaded, and careful matching of the file to the size of the canal is necessary. Strict adherence to these simple set-up and calibration procedures and the use of the apex locator in conjunction with high-quality, standardized diagnostic radiographs provide the clinician with an accurate and useful adjunct to endodontic therapy.

Radiographic and electronic diagnostic systems.

Radiography forms the basis for determining the length of tooth in endodontic therapy. Radiographs can be manipulated by digital image processing, which can improve their diagnostic quality as well as enable the images to be stored electronically. Electronic apex locators, when used in conjunction with radiographs and electronic imaging systems, become useful adjuncts in endodontic treatment. They provide the clinician with the ability to accurately determine the length of tooth, thus making apex locators an important component in endodontic therapy.