A comparative in-vitro study of the bactericidal efficacy of sodium hypochlorite and chlorhexidine gluconate plus cetrimide on root canal anaerobic bacterial flora

INTRODUCTION: The permanence of necrotic tissues and/or bacteria may be responsible for persistent root canal infection. Root canal irrigation plays an important role in the success of endodontic treatment given that, on the one hand, it encourages the progressive elimination of the smear layer and, on the other, it neutralises microbic flora within the canal. The aim of this study was to test root canal irrigants from a microbiological point of view: sodium hypochlorite 5% (Niclor Ogna, Milan) and a new generation irrigant based on chlorhexidine gluconate and cetrimide (Cetrexidine VEBAS S. Giuliano Milanese-MI). METHODS: The experiments were performed on a series of obligatory anaerobic bacteria which are most frequently found in the endodontium, all belonging to the international collection "American Type Culture Collection" (ATCC) and supplied by Dasit SpA, Cornaredo (MI). The following bacterial strains were used in the experiment: Actinimyces odontolyticus ATCC 17929, Fusobacterium nucleatum ATCC 25586, Prevotella melanginogenica ATCC 25845, Porphyromonas gingivalis ATCC 33277. The working concentration (CFU/ml) was defined as 0.5 McFarland which corresponds to a concentration of microorganisms equivalent to approx. 1.5 x 10(3) bacteria. Each irrigant was kept in contact with the bacterial species used for this experiment for 10', 20', 30'. RESULTS: The results obtained confirm the bactericidal efficacy of both irrigants used, even after a short contact time. CONCLUSIONS: This does not mean that all irrigants are the same and/or promise the same results. This was a microbiological study, but in practice it is important to bear in mind other variables, such as contact time. Moreover, in order to increase the probability of endodontic treatment, root canal irrigants are also required to satisfy other criteria: biocompatibility, scarce toxicity, high proteolytic power.     

A new muffle model system to study root canal morphology and instrumentation techniques

A new muffle model system is presented using the principle of internal indexing. The system is composed of a metal stand, four pins, and a single Teflon mold that is used for the investment of all teeth. This system is very precise, reproducible, and versatile. The sectioned specimens can easily be stored assembled, as opposed to previous systems that rely on external indexing.     

Effectiveness of two rotary instrumentation techniques for cleaning the root canal

An in vitro study was undertaken to compare the efficiency of two rotary endodontic devices for cleaning the root canal wall(s). Only mesial roots of mandibular first molar were used. Forty roots were classified into two equal groups. Group (I) was instrumented using the Canal Finder system, Group (II) was instrumented using Nickel Titanium files. In both groups half of the specimens received a final flush of 17% EDTA and 5.25% NaOCl solutions. Roots were sectioned longitudinally and Scanning Electron Micrographs were taken at three levels (Coronal, Middle and Apical) of each section of the prepared roots. Statistical analysis of the results showed that the Canal Finder system produced a clean canal surface when 17% EDTA and 5.25% NaOCL were used as an irrigating solutions, while Nickel Titanium files had a superior cleaning efficiency than the Canal Finder with either irrigating solution.     

A Monte Carlo study of the inferential properties of three methods of shape comparison

Three inferential morphometric methods, Euclidean distance matrix analysis (EDMA), Bookstein's edge-matching method (EMM), and the Procrustes method, were applied to facial landmark data. A Monte Carlo simulation was conducted with three sample sizes, ranging from n = 10 to 50, to assess type I error rates and the power of the tests to detect group differences for two- and three-dimensional representations of forms. Type I error rates for EMM were at or below nominal levels in both two and three dimensions. Procrustes in 2D and EDMA in 2D and 3D produced inflated type I error rates in all conditions, but approached acceptable levels with moderate cell sizes. Procrustes maintained error rates below the nominal levels in 2D. The power of EMM was high compared with the other methods in both 2D and 3D, but, conflicting EMM decisions were provided depending on which pair (2D) or triad (3D) of landmarks were selected as reference points. EDMA and Procrustes were more powerful in 2D data than for 3D data. Interpretation of these results must take into account that the data used in this simulation were selected because they represent real data that might have been collected during a study or experiment. These data had characteristics which violated assumptions central to the methods here with unequal variances about landmarks, correlated errors, and correlated landmark locations; therefore these results may not generalize to all conditions, such as cases with no violations of assumptions. This simulation demonstrates, however, limitations of each procedure that should be considered when making inferences about shape comparisons.     

A comparative study of alternative bone-conduction calibration methods

The accepted instrument for calibrating the bone-conduction section of an audiometer is the artificial mastoid. For a variety of reasons, alternative calibration methods are in general use. Three common methods are: (1) the input voltage method; (2) the real-ear threshold method using normal-hearing listeners; and (3) the real-ear threshold method using subjects with sensorineural hearing loss. The present investigation compared these methods for both accuracy and efficiency. There were no significant differences in accuracy found among the three calibration methods. Substantial differences in efficiency were noted, however. When accuracy and efficiency are considered, the input voltage method appears to be the best alternative method for calibrating the bone-conduction system of an audiometer.     

Effect of Er:YAG laser treatment on the root canal walls of human teeth: an SEM study

The purpose of the study was to assess the applicability of a new ITKA GSD Basic 250 electrosurgical unit (ESU) to urologic endoscopic surgery, laparoscopic surgery and open urologic surgery, its possible interference with videorecording and stray currents in healthy tissues. A new ITKA GSD Basic 250 ESU (test ESU) was used and compared to conventional ESU (Berchtold Elektrotom 390 as reference ESU). Experimental surgery was carried out on three female pigs, which underwent endoscopic, laparoscopic and open surgery. Altogether 29 patients underwent either endoscopic or open surgery with the test ESU. In experimental surgery, the ideal cutting and coagulation settings of the test ESU were in the range 15-25% for endoscopic surgery. In laparoscopic surgery, tissues were ideally resected and removed at 10-15% power settings. In open experimental surgery, the ideal power settings were 25-30%. In human surgery, the test ESU operated well at 25-35% power settings in endoscopic surgery, while in open surgery on humans the ideal settings were 25-35% in monopolar use and 20-25% in bipolar use. When used for endoscopic operations, the test ESU did not interfere with videorecording. Nor were any adverse effects seen in the surrounding tissues. The patients had neither early nor late complications. Histopathological findings revealed no differences in healing between the test ESU and reference ESU. Experimental and patient surgery showed the test ESU to be both safe and effective. It is suitable to be used in urologic endoscopic surgery, laparoscopic surgery and open urologic surgery. It does not interfere with videorecording or cause harmful stray currents in surrounding tissues. Power can be adjusted linearly and precisely. Low-power operation is also possible.     

Comparative study of two filling techniques using glass-ionomer (Ketac-endo) root canal cement on fracture resistance of endodontically treated roots (in vitro)

Forty freshly single rooted teeth were selected for this study. The coronal part of teeth were decapitated and the root canals were prepared by modified step-back technique with K-flex files to size 35# at the apex, five ml of 5.25% NaOCl was used as irrigating solution. According to the dentin thickness at the mesio-distal direction of the prepared roots, roots were divided into two groups: Group (I), dentin and cementum thickness from 1.5-2 mm, and Group (II), dentin and cementum thickness 1 mm. According to the filling technique used the teeth were subdivided into four subgroups each of five teeth; Subgroup (A) single gutta-percha cone and Ketac-endo root canal sealer, Subgroup (B) lateral condensation technique with gutta-percha and Ketac-endo sealer, Subgroup (C) laterally condensed gutta-percha with Roth 801 cement and Subgroup (D) teeth left unfilled as negative controls. The prepared roots were placed into acrylic resin so that 10 mm of the root was exposed. A slowly increasing force was applied vertically using a blunt punch with 1 mm tip thickness attached to Instron testing machine. The results showed that group (I) with 1.5-2mm dentin thickness required greater force to fracture in all experimental groups, than that of group (II) with 1 mm dentin thickness. So the amount of remaining dentin thickness significantly affected the resistance to fracture of the prepared roots.     

A comparative study of synchronised and conventional culture methods on the micronucleus dose-response curve

The involvement of GABAA and GABAB receptors in neural mechanisms responsible for the production of theta rhythms in hippocampal formation (HPC) slices is addressed in the present study. In a number of papers published in the last decade, we have demonstrated that theta-like activity can be successfully recorded in the limbic cortex maintained in vitro when the cholinergic agonists, acetylcholine, carbachol or muscarine, were added to the bath. Recently, we have also shown a strong GABAA modulation of the cholinergic-induced in vitro theta-like activity. This study presents a report of the first demonstration of in vitro theta-like field responses induced a consequence of simultaneously inhibiting hippocampal GABAA and GABAB receptors. HPC slices (350 microns) were maintained in a gas-liquid interface chamber (35 degrees C). Theta-like activity was induced in the presence of bath perfusion of bicuculline (GABAA antagonist) and 2-hydroxysaclophen (GABAB antagonist). This in vitro induced field response was antagonized both by muscimol (GABAA agonist) and baclophen (GABAB agonist). In addition, the experiments presented here revealed that bicuculline/2-hydroxysaclophen-induced in vitro theta-like activity also had a strong cholinergic M1 involvement: it was abolished by hemicholinium-3 (choline transport blocker) and pirenzepine (specific antagonist of M1 receptor), but not by gallamine (specific antagonist of M2 receptor). The results of the present study provided further evidence for a strong GABAergic/cholinergic interaction in the neural mechanism responsible for production of theta-like activity in the hippocampal formation slices.     

A phenomenological study of the shape memory effect in polycrystalline uranium-niobium alloys

When uranium-niobium alloys containing between 13.9 and 17.9 at. pct Nb are quenched to room temperature from the BCC (γ) phase at elevated temperatures, diffusion-controlled precipitation of the equilibrium phases is prevented and martensitic transformations to transition phases occur instead. Dilatometry was used to detect transformation temperatures and with the help of X-ray diffraction analysis, a metastable phase diagram was established. At room temperature after quenching, alloys containing < 15.2 at. pct Nb were monoclinic (α″) and those with < 16.6 at. pct Nb were tetragonal (γ°). The deformation behavior and shape memory effects (SME) accompanying the reverse martensitic phase transformations in polycristalline specimens were surveyed and characterized phenomelogically. From uniaxial tensile tests at room temperature, macroscopic stress-strain parameters, associated with the reversible deformation modes in the α″ and γ° martensites, were defined and their composition and structural state dependencies delineated. A diffuse maximum manifested in the stress-strain diagrams was identified with the reversible strain limit, which varied inversely and continuously with composition. A concentration-independent value of 693 MPa was found for the plastic yield strength of the alloys. All the alloys exhibited heat-activated shape recovery but the degree depended on structural state and composition. The α″ alloys showed a much larger effect than γ° alloys. Shape recovery occurred in two stages in all alloys. The first stage of recovery accompanied martensite reversion but final reversion to the equilibrium y phase was not accomplished until much higher temperatures were reached. Rapid, low temperature aging reactions were thought to affect the finish of shape recovery and delay it to higher temperatures. Formerly with Metals and Ceramics Division, Oak Ridge National Laboratory     

A comparative study of rifapentine treatment and three years follow-up on initial pulmonary tuberculous

A clinical study about the efficacy of rifapentine in the treatment and 3 years' follow up on initial pulmonary tuberculous patient. Altogether 267 patients of initial pulmonary tuberculosis with positive smears were randomly divided into 3 groups; Group I with DL473 twice-weekly (2HE+L2/7H2L2), Group IIARFp twice-weekly (2HE+R2/7H2R2) and Group IIBRFP daily (2HRE/7HR) for controls. Results are: the conversion rate to smear negative are 96.0%, 96.4% and 97.1% respectively (P > 0.05); the sputum conversion rate by cultures are 98.0%, 95.7% and 96.4% respectively (P > 0.05). From X-Ray pictures, the treatment effect of Group I are similar to that of Group IIB. But in Group I with less side action were observed. The relapse rate of the three groups are 2.6%, 3.8% and 3.1% respectively (P > 0.05). From this investigation, we can draw a conclusion that the twice-weekly of rifapentine has at least an effect similar to rifampicin given daily. Further investigation of DL473 once weekly will soon be followed.     

A comparative study of the porous TiNi shape-memory alloys fabricated by three different processes

Porous TiNi shape-memory alloys (SMAs) have been successfully fabricated by three different processes, including capsule-free hot isostatic pressing (CF-HIP), conventional sintering (CS), and self-propagating high-temperature synthesis (SHS). A systematically comparative investigation was made on their phase transformation behaviors, mechanical properties, superelasticity, and damping performance. The results show that the CF-HIP process is the best among these methods. By controlling the processing parameters of CF-HIP, the porous TINi SMA shows the expected pore characteristics, such as a round pore shape and a homogeneous pore distribution. The porous TiNi SMA produced by CF-HIP also exhibits good properties, such as superior superelasticity (up to 4 pct recoverable strain), a flat stress yield plateau, and a high compressive strength, similar to those of the dense TiNi SMAs. In addition, the porous TiNi SMA produced by CF-HIP has a much smaller strain hysteresis, superior damping performance to a porous TiNi SMAs produced with CS, and SHS.     

Desmoplastic fibroma of bone. (A study of three cases)

Three cases of demoplastic fibroma of bone are presented. Thirty six cases already reported in the world literature are reviewed, making the present total thirty nine cases. The extreme rarity of the tumor is emphasised, and its clinical, radiographic, morphological and pathological aspects discussed. Though the absence of metastases or histologically abnormal cells attest to its benign nature it has a definite tendency to local recurrence. Differential diagnosis and treatment are discussed.     

A comparative study of methods to validate formaldehyde decontamination of biological safety cabinets

Methods of validation of formaldehyde decontamination of biological safety cabinets were compared. Decontamination of metal strips inoculated with Mycobacterium bovis, poliovirus, or Bacillus spp. spores was compared with the results obtained with three biological indicators. Conditions for successful decontamination, particularly relative humidity, were defined. The Attest 1291 biological indicator was the only biological indicator which was an aid in the detection of gross decontamination failure.     

A study on predicting factors of the effect of intra-arterial infusion chemotherapy in patients with bladder cancers: the usefulness of in-vitro chemisensitivity test measuring intracellular ATP contents (ATP assay)

We studied a relationship between in vitro sensitivity of the tumors to anti-cancerous drugs and histopathological effectiveness of an intra-arterial infusion chemotherapy in 15 patients with bladder cancers. The in vitro sensitivity test was performed by measuring intra-cellular ATP contents (ATP assay). The intra-arterial chemotherapy were performed by injecting methotrexate (MTX), adriamycin (ADM) and eisplatin (CDDP) from the internal iliac artery. When the intra-cellular ATP contents of the tumor cells treated with an anti-cancerous drug decreased to less than 50% of the untreated tumor cells, the tumor was evaluated as sensitive to the drug. The effectiveness of the chemotherapy were histopathologically evaluated by a pathologist according to the response criteria for bladder cancer treatment. When the histopathological responses of higher than grade 2 were observed in the tumor, the chemotherapy was evaluated as effective. In 8 of 9 tumors sensitive to ADM, chemotherapy were effective histopathologically and in all 6 tumors resistant to ADM, histopathological response of the chemotherapies were poor. The overall coincidence ratio between sensitivity to ADM and the histopathological effectiveness of the chemotherapy was 93%, showing statistically significant correlation. In 7 of 12 tumors sensitive to CDDP, the chemotherapies were effective and in 2 of 3 tumors resistant to CDDP, the chemotherapies were ineffective. Although the overall coincidence ratio between the sensitivities to CDDP and chemotherapeutic effectiveness was 60%, there was no significant correlation between them. In 7 of 8 tumors sensitive to both of ADM and CDDP, the chemotherapies were effective and in 6 of 7 tumors resistant to at least one of them, the chemotherapies were ineffective. (ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of an isothermal action on the functional properties and the shape memory effect parameters of a TiNi(Mo,V) alloy

The influence of annealing at 450°C for 1 h on the shape memory effect parameters of the Ti₅₀Ni_48.7V₁Mo_0.3 alloy is studied over a wide temperature range at a constant load. Annealing is shown to decrease the critical stresses of the martensitic shear, to increase the temperature hysteresis wide during a repeated shape memory effect, and to decrease this effect.     

A clinical and histological comparative study of the effect of nifedipine and phenytion on human gingiva

Ten patients manifesting gingival enlargement were chosen for this study. Five patients had been treated with 4 mg nifedipine per day as a treatment for angina pectoris, while the other five patients treated with phenytion as an anticonvulsant drug. Clinical and histological data showed that nefidipine induced gingival hyperplasia which is of close similarity to that induced by phenytion despite the differences in target tissue.     

A comparative study on egg hatching methods and oncosphere viability determination for Taenia solium eggs

The efficiencies of an enzyme method and the sodium hypochlorite method in hatching eggs of Taenia solium (Henan strain) were compared. The viability of the hatched oncospheres was determined by staining with trypan blue. For the former method, the hatching rate and viability percentage were 85.7% and 79.7%, respectively. The corresponding figures for the latter method were 97.9% and 86.7%, respectively. These findings indicate that the sodium hypochlorite method is a simple, efficient and practical method for hatching eggs of Taenia solium.     

The effect of serrations on carbon fibre posts-retention within the root canal, core retention, and post rigidity

The retention in root canals of serrated carbon fibre Composiposts and stainless steel Paraposts was tested under tensile load. Twenty unrestored human roots were endodontically prepared and root filled. Two groups of 10 roots received 1.4-mm Composiposts or 1.25-mm Paraposts luted with a resin cement. The specimens were then embedded in acrylic resin and mounted in an Instron machine. The tensile force (kg) required to dislodge the posts was recorded and analysed with Student's test. The results revealed that there was no significant difference in the retention of either post (P > .05). The rigidty of 10 1.4-mm serrated Composiposts was tested in a three-point bend test in an Instron machine, and the retention of composite cores to 10 of these posts under tensile force was also tested. The results from these tests were compared to previous data from the authors' laboratory and revealed that the serrations significantly reduced the rigidity of the post (P < .001) and increased the retention of a core material (P < .001).