bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid transport and dye penetration along root canal fillings
Authors: WU M‐K. , DE GEE A. J. , WESSELINK P. R.
Published: September 2007

Dye penetration along root canal fillings may be hindered by the presence of entrapped air. In this study, the sensitivity of a dye penetration method was compared with that of a fluid transport model. Sixty root sections from human maxillary central incisors were prepared and obturated by a modified technique to ensure a slight amount of leakage, and divided into three equal groups. Twenty root sections were first mounted in a fluid transport device and assessed for fluid transport under 10 kPa (0.1 atm.) pressure. Another 20 root sections were mounted in the same device before being subjected to air transport under the same pressure. The remaining 20 root sections were not exposed to fluid or air transport. Then, all the 60 root sections were assessed for penetration of a 2% methylene blue solution. The results showed that fluid transport was a much more sensitive method of detecting voids along root canal fillings than dye penetration. After fluid transport for 3 h under low pressure, to eliminate entrapped air, dye penetrated significantly deeper than without previous fluid transport, which suggested that entrapped air in voids along the root canal filling prevented dye penetration.
Irritating effect of formocresol after pulpectomy in vivo
Authors: YAMASAKI M. , NAKAMURA H. , KAMEYAMA Y.
Published: September 2007

A study was carried out to investigate the effect of formocresol (formalin‐creosote) on the periapical tissue after pulpectomy in rats. A pulpectomy was performed on the mesial root of the right mandibular first molar, and, in group A, a paper point containing saline was inserted into the root canal. In group B, a paper point containing formocresol was inserted, and in group C, a drop of formocresol was applied and a paper point containing formocresol was inserted into the root canal. The periapical tissue was examined histologically and histometrically at 3, 7, 14, and 28 days after insertion, and the inflammatory cells and fibroblasts in the apical granulation tissue were also counted. Histologically, in group A, the inflammation observed was slight at 14 and 28 days, while in groups B and C, a moderate inflammation remained. Histometrically, the area of the apical periodontal ligament in groups B and C was increased significantly compared with that in group A at 14 and 28 days. The inflammatory cell count in groups B and C increased significantly compared with that in group A at 7, 14, and 28 days, whereas the flbroblast count in Groups B and C decreased compared with that in Group A at 7, 14, and 28 days. These results demonstrate that formocresol delayed the healing of periapical tissue after pulpectomy.
Prescribing endodontic retreatment: towards a theory of dentist behaviour
Authors: KVIST T. , REIT C. , ESPOSITO M. , MILEMAN P. , BIANCHI S. , PETTERSSON K. , ANDERSSON C.
Published: September 2007

The large variations observed in dentists' management of periapical lesions in endodontically treated teeth suggest that disease concepts used in clinical practice should be investigated. In the present study it was hypothesized that dentists regard various periapical conditions as different stages on a health continuum. Variations could then be regarded as the result of the individuals selection of differing cut‐off points for prescribing retreatment.

The hypothesized decision‐making model was tested using dental students in Amsterdam (Holland), Gothenburg (Sweden) and Pavia (Italy). The students were shown six simulated cases among which the quality of root filling seal and presence of post and crown were systematically varied. For each case, management of five periapical conditions was assessed. Five options were offered: no therapy, wait‐and‐see, nonsurgical retreatment, surgical retreatment, and extraction. For each examiner and case a ‘retreatment preference score (RPS)’ was established.

The investigation showed large interindividual variations in RPS. A statistically significant higher mean RPS was seen among students in Pavia compared with students in Amsterdam and Gothenburg. Among all observers and cases it was found that if retreatment was proposed for a certain size of lesion, retreatment was subsequently selected for all larger lesions.

The experiment gave evidence in support of the proposed hypothesis. The data also suggest that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of the original treatment.
A new non‐instrumental technique for cleaning and filling root canals
Authors: LUSSI A. , MESSERLI L. , HOTZ P. , GROSREY J.
Published: September 2007

The aim of this in vitro study was to test the ability of a novel non‐instrumental technique to prepare and obturate root canals. Cleaning of the root canal system was achieved with a device which was able to develop, under reduced pressure, controlled cavitation. The same device was used for proper drying and subsequent obturation of the root canal system. A total of 55 freshly extracted molars with 120 canals were treated either by the step‐back technique and lateral condensation of gutta‐percha and AH26 as a sealer or by the new device. The teeth were then sectioned horizontal to the long axis of the root canal and examined by light microscopy. The cross‐sectional area, area with residual pulpal tissue and voids were assessed morphometrically. Overall, the treatment with the new device resulted in similar cleanliness and obturation quality when compared with the control group. Total treatment time using the new non‐instrumental technique, however, was less than half of that using hand instrumentation.
Evaluation of long‐term calcium hydroxide treatment in avulsed teeth — an in vivo study
Authors: DUMSHA T. , HOVLAND E. J.
Published: September 2007

Calcium hydroxide has been advocated for use in avulsed teeth as a temporary dressing in an attempt to prevent or inhibit external resorption. However, there have been no long‐term histological studies that have examined gutta‐percha versus calcium hydroxide treatment in avulsed teeth. The purpose of this study was to determine the long‐term therapeutic effect of calcium hydroxide therapy in avulsed teeth. Six adult macaca monkeys were anesthetized and all four maxillary incisors were extracted and bench‐dried for 25 min. The teeth were replanted and splinted with composite for approximately 2 weeks. Each animal served as its own control and the teeth were accessed, instrumented, and filled with either Ca(OH)2 or gutta‐percha and AH26 cement. All access openings were filled with composite. The Ca(OH)2 was replaced twice during the experimental period (approximately every 8 weeks). The animals were killed between 5 and 7.5 months postavulsion. The teeth were removed, sectioned, and examined histologically by two examiners. The results of the histological evaluation of external resorption indicated that there were no statistically significant differences in resorption indices between the teeth obturated with gutta percha or with calcium hydroxide (P>0.05). Replacement resorption was the primary cause of root destruction and only a few histological sections exhibited evidence of inflammatory resorption.
In vitro radicular temperatures produced by injectable thermoplasticized gutta‐percha
Authors: WELLER R. N. , KOCH K. A.
Published: September 2007

In vitro temperatures produced in the root canal and on the root surface were measured simultaneously as heated gutta‐percha was injected into the prepared canal. The canals were obturated with the Obtura II heated gutta‐percha system with temperature settings of 160, 185, and 200°C. The mean intracanal temperatures ranged from 40.21 to 57.24°C, whereas the mean root surface temperatures were recorded from 37.22 to 41.90°C for all three temperatures tested. The rise in temperature on the root surface was below the critical level of 10°C and should not cause damage to the periodontal ligament.
Single visit root canal treatment: incidence of postoperative pain using three different instrumentation techniques
Authors: FAVA L. R. G.
Published: September 2007

A clinical study was carried out on nonvital maxillary central incisors to evaluate the incidence of postoperative pain following single‐visit root canal treatment using three different instrumentation techniques. Ninety teeth from 78 patients whose ages ranged from 14 to 63 years were selected and divided into three groups. Each group (30 teeth) was prepared by a different coronal‐to‐apical technique using different instrument movement depending upon the technique employed: modified double‐flared, crown‐downpressureless and balanced force techniques. No difference was observed in the incidence of postoperative pain among the groups.
Diagnostic confidence and the accuracy of treatment decisions for radiopaque periapical lesions
Authors: STHEEMAN S. E. , MILEMAN P. A. , van't HOF M. A. , van der STELT P. F.
Published: September 2007

The periapical radiograph is a tool used in the diagnosis of periapical bone pathology. Radiographic diagnosis might therefore influence endodontic treatment planning and the quality and the cost of dental health care. The hypotheses were tested that (1) the subjective prevalence of a lesion would be associated with the accuracy with which it is diagnosed, (2) ‘confident dentists’ would be as accurate in their diagnosis as ‘doubtful dentists’ and (3) the diagnostic confidence of dentists for the diagnosis of periapical pathology would not influence their treatment planning. It was found that the probability of an appropriate treatment decision increased when dentists were relatively confident about a diagnosis. The results showed, furthermore, that the accuracy of diagnostic decisions increased when the dentist's confidence about a particular decision was high. Ways to increase diagnostic accuracy of radiopaque periapical pathology are proposed as a result of this study.
The smear layer: a phenomenon in root canal therapy
Authors: ŞEN B. H. , WESSELINK P. R. , TÜRKÜN M.
Published: September 2007

When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the prescence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and if delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCI solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.
Pulpotomy of carious vital teeth with periapical involvement
Authors: ÇALIŞKAN M. K.
Published: September 2007

Twenty‐six permanent vital molars with carious pulp exposures and periapical involvement presenting as radiolucencies or radiopacities on radiographic examination, in patients aged between 10–24 years, were treated using an atraumatic surgical technique with calcium hydroxide alone.

The healing was evaluated using clinical and radiographic criteria: absence of clinical symptoms, sensitivity of the radicular pulp, formation of a hard tissue barrier in the exposed area, resolution of periapical involvement and no intraradicular pathosis radiographically. Assessed by these criteria, successful results were achieved in 24 teeth. The observation period following pulpotomy treatment was 16–72 months. The favourable results of this study demonstrate that pulpotomy treatment in teeth with cariously exposed vital pulps and with periapical involvement may be an alternative treatment to root canal therapy.
A 1‐year follow‐up study on leakage of four root canal sealers at different thicknesses
Authors: WU M.‐K. , WESSELINK P. R. , BOERSMA J.
Published: September 2007

Determination of leakage using a fluid transport model allows measurement of leakage in a longitudinal manner. Leakage of four sealers at three different thick‐ nesses in 225 bovine root sections, after storage in water for 1 year, was measured again using the same method‐ ology. The change in seal over time for each sealer was observed. The results after the second measurement showed that every sealer produced the best seal when the sealer layer was the thinnest. AH26, Ketac‐Endo and Tubli‐Seal showed a reduction in leakage over time and gave significantly less leakage than Sealapex (P<0.005). Sealapex showed sigdicantly more leakage after storing in water for 1 year (P<0.005). Therefore, the long‐lasting seal of sealer may, among other influencing factors, depend on the layer thickness and the solubility of the material.
Torsional and stiffness properties of nickel–titanium K files
Authors: CAMPS J. J. , PERTOT W. J.
Published: September 2007

The purpose of this study was to compare stiffness and resistance to fracture of four brands of nickel titanium K files. Instruments of sizes 15 to 40 were tested according to ANSI/ADA Specification No. 28. Resistance to fracture was determined by twisting and measuring the maximum torque and angular deflection at failure. Stiffness was determined by measuring the moment required to bend the instrument 45°. The permanent deformation angle remaining between the tip and the flutes of the instruments after bending ceased was also recorded. Nickel titanium K files satisfied and far exceeded specification standards for stiffness. They also satisfied and exceeded the standards for angular deflection at failure. They met or exceeded the maximum torque at failure standards in all sizes except for the size 40 of the Maillefer Niti, and the size 30 of the Mac Spadden Niti. Nickel titanium K files presented a null permanent deformation angle. Clinical studies are required to evaluate the influence of low bending moment on other properties such as breakage and canal transportation.
Machining efficiency of nickel‐titanium K‐type files in a linear motion
Authors: CAMPS J. J. , PERTOT W. J.
Published: September 2007

The purpose of this study was to compare, in vitro, the machining efficiency of four brands of nickel‐titanium files and two brands of stainless steel K‐type files. Instruments sizes 15 to 40 were tested in a linear motion simulating the clinical motion used to remove a file from the canal. The tips of the loaded files were in contact with a resin block. The load applied increased with file size. An indentation varnish caliper was used to measure the depth of the groove after 100 back‐and‐forward motions. The stainless steel instruments with a triangular cross‐section were more efficient than the stainless steel instruments with a square cross‐section. There was a significant discrepancy between the machining ability of the nickel‐titanium K files. The Maillefer instruments were the most efficient.
Associations of endodontic symptoms and signs with particular combinations of specific bacteria
Authors: GOMES B. P. F. A. , LILLEY J. D. , DRUCKER D. B.
Published: September 2007

Significant associations have been reported between (a) specific bacterial species isolated from root canals and (b) between individual bacterial species and endodontic symptoms and signs. The prime objective of this study was to determine whether particular combinations of specific bacteria are associated with individual endodontic symptoms and signs. Seventy root canals were investigated microbiologically taking care to maintain the viability of obligate anaerobes, which accounted for 64% of the total species isolated, including Peptostreptococcus micros, Prevotella melaninogenica, Prevotella oralis, Eubacterium aerofaciens, Eubacterium lentum, Fusobacterium nucleatum, Prevotella buccae and Prevotella intermedia. Significant associations were found between individual clinical features and the following pairs of species: (a) pain (37 cases) and Peptostreptococcus spp./Prevotella spp., Peptostreptococcus spp./Prevotella melaninogenica, Pstr. micros/Prev. melaninogenica (all P < 0.01); (b) swelling (23 cases) and Pstr. micros/Prevotella spp. (P < 0.01); (c)‘Wet’canal (57 cases) and Prevotella spp./Eubacterium spp. (P < 0.01), Peptostreptococcus spp./Eubacterium spp. (P < 0.05). Thus data from this investigation suggests that statistically significant associations exist between individual endodontic symptoms and signs and particular combinations of specific bacteria.
The use of a radiopaque contrast medium in endodontic radiography
Authors: SHEARER A. C. , WASTI F , WILSON N. H. F.
Published: September 2007

A series of in vitro studies were carried out to investigate the use and application of a radiopaque contrast medium in conventional periapical dental radiography for the diagnosis and evaluation of root canal systems. The water‐soluble radiopaque contrast medium was introduced into the root canals of 30 first permanent maxillary and 30 first permanent mandibular molar teeth. The radiographic images of these teeth with and without radiopaque contrast medium in the root canal systems were compared and contrasted. Further comparisons were made with the same teeth rendered transparent.

The results indicate that by standardizing the diagnostic criteria the inter‐examiner reliability was in good agreement; it was independent of the radiographic technique used. The validity of the radiographs was enhanced by the use of the radiopaque contrast medium. The results confirm that, with the use of a radiopaque contrast medium, images of root canal systems are easier to read and interpret than plain radiographic images of root canal systems.

The use of radiopaque contrast medium in endodontic radiography may be a valuable aid in the diagnosis and evaluation of root canal systems. This system would complement rather than replace plain radiography.
Adherence of Streptococcus gordonii to smeared and nonsmeared dentine
Authors: LOVE R. M.
Published: September 2007

The purpose of this study was to investigate the adherence of Streptococcus gordonii to smeared and non‐smeared dentine and to assess the influence of patent dentinal tubules on bacterial retention. In order to examine bacterial adherence, 10 non‐smeared (group 1) and 10 smeared samples (group 2) of outer root dentine were prepared from teeth exhibiting dentine sclerosis. Ten non‐smeared samples from inner coronal root dentine that did not exhibit sclerosis were prepared in order to study the influence of patent tubules on bacterial retention (group 3). Cells of the bacterium were radioactively labelled and an adhesion assay was performed. The number of bacteria adhering to the dentine surface was determined by scintillation counting. The results show that the number of bacteria adhering to both smeared and non‐smeared outer sclerotic dentine was low (0.3% of inoculum), and there was no significant difference between the groups (P > 0.3). A significantly higher number of bacteria was retained on the inner non‐smeared coronal root dentine (P < 0.0001) compared to groups 1 or 2. The results suggest that dentinal smear layers do not enhance or impede bacterial adherence to the dentine matrix. Dentinal surfaces with patent dentinal tubules retain more bacteria than a smeared surface.
Assessing apical deformation and transportation following the use of LightSpeedTM root‐canal instruments
Authors: KNOWLES K. I. , IBARROLA J. L. , CHRISTIANSEN R. K.
Published: September 2007

The LightSpeedTM root canal instrument is similar in design to the Canal Master instrument with the exception of being engine driven and fabricated from nickel‐titanium alloy. The purpose of the design of these instruments is to reduce apical transportation of the canal during cleansing and shaping procedures. Twenty extracted human molar teeth with roots of varying degrees of curvature were used in this study. A double exposure radiographic technique was used to assess the Presence or absence of apical transportation resulting between the initial instrument and the final instrument, a size 50 LightSpeedTM Only one of the 20 teeth examined exhibited apical transportation. Results of this study suggest that little or no apical canal transportation could be expected when curved canals are instrumented using the LightSpeedTM root canal instruments.
Penetration of smeared or nonsmeared dentine by Streptococcus gordonii
Authors: LOVE R. M. , CHANDLER N. P. , JENKINSON H. F.
Published: September 2007

The purpose of this study was to investigate the penetration of smeared and nonsmeared dentine by Streptococcus gordonii. Prepared human roots, grouped as either nonsmeared or smeared, were immersed in a suspension of S. gordonii cells for 3 weeks. The roots were then prepared for scanning electron microscopy and histological analysis. Dentine discs prepared from coronal dentine were grouped similarly. Using a fluid filtration apparatus, the hydraulic conductance (Lp) of each disc was determined before and after incubation with bacterial suspension. Scanning electron microscopy evaluation of the roots following infection with bacteria showed no change in the smear layer (P<0.0001). Histological sections revealed that bacterial penetration of all the nonsmeared samples had occurred, while nine out of 10 smeared samples showed no bacterial penetration (P<0.0001). The Lp of the nonsmeared discs was significantly reduced by 42% (P<0.0001) after bacterial penetration. However, the smeared samples revealed a 1% reduction in Lp which was not significant (P > 0.05). The results suggest that dentinal smear layers are an effective barrier to dentinal tubule invasion by S. gordonii.
Permeability, morphologic and temperature changes of canal dentine walls induced by Nd: YAG, CO2 and argon lasers
Authors: ANIĆ I. , TACHIBANA H. , MASUMOTO K. , QI P.
Published: September 2007

The permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2 and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single‐rooted teeth were enlarged using a step‐back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between Iased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among C02 laser and Nd:YAG compared with control group (P<0.01). Rises in temperature ranged from a minimum of +10.1 °C (CO2 laser) to a maximum of +54.8 °C (argon laser). All three laser devices appeared capable of producing a glazed‐like surface and craters.
The effect of tubular penetration of root canal sealers on dye microleakage
Authors: ŞEN B.H. , PIŞKIN B. , BARAN N.
Published: September 2007

An in vitro study of a possible correlation between penetration of dentinal tubules by four root canal sealers and microleakage of external fluids into the canal was done using a dye leakage method and scanning electron microscopy. The root canals of 45 teeth were instrumented and the smear layer removed prior to obturation of root canals with gutta‐percha and one of four sealers: Diaket, Endomethasone, CRCS or Ketac‐Endo. The extent of leakage was scored after immersion in India ink for 72 h. The same specimens were also used for scanning electron microscopic evaluation. There was a statistical difference in leakage patterns between the groups (P<0.05). Diaket had lower microleakage scores than the other sealers (P<0.05). When the scores for penetration of sealers into the tubules were analysed, Ketac‐Endo demonstrated the least penetration (P<0.01). There appeared to be a converse relation between tubular penetration and dye leakage, but the correlation was not statistically significant (P<0.05).
Plasma catecholamine and haemodynamic responses to surgical endodontic anaesthetic protocols
Authors: GUTMANN J. L. , JR FRAZIER L. W. , BARON B.
Published: September 2007

The effects of varying clinically relevant patterns of anaesthetic‐vasoconstrictor combinations used for peri‐radicular surgery on plasma concentrations of catecholamines and haemodynamic responses was studied in the canine model. Five mongrel dogs were anaesthetized with sodium pentobarbital. A femoral canula was inserted to measure central blood pressure and an ECG was used to monitor heart rate and any associated arrhythmias. Femoral venous blood samples were drawn before initial injection and at 3 and 10 min after injections. Plasma catecholamine concentrations were determined using high pressure liquid chromatography (HPLC). Injection protocols used three time periods, 30, 60 and 90s, with solutions containing 1:100000 and 1:50000 adrenaline. No significant changes in heart rates or presence of arrythymias were noted over the experimental protocol. Catecholamine levels in pico moles mL‐1 were within the normal range at the 3‐min sample level. At the 10‐min sample time there was a more erratic range of concentrations, with most samples within the normal range. This may have been due to endogenous release of catecholamines in specific animals. The data identified trends in both the haemodynamic parameters and plasma catecholamine levels that can legitimately support the careful use of higher levels of a vasoconstrictor when patient profiles and surgical needs dictate.
Susceptibility of Actinomyces israelii to antibiotics, sodium hypochlorite and calcium hydroxide
Authors: BARNARD D. , DAVIES J. , FIGDOR D.
Published: September 2007

Actinomyces israelii has been repeatedly implicated as a cause of failure of endodontic therapy. This study investigated the antimicrobial effect of antibiotics as well as intracanal medicaments, sodium hypochlorite solution and calcium hydroxide, on this important pathogen. Growth of A. israelii was inhibited by low concentrations of antibiotics, yet high concentrations were not bactericidal for A. israelii over 1 week. When A. israelii was exposed for 2‐6 weeks at concentrations equivalent to clinical serum levels, the antibiotics were lethal. The results reveal a species ‐ specific antibiotic tolerance for A. israelii. Both sodium hypochlorite solution and calcium hydroxide were found to be highly eifective in killing A. israelii.
Effect of various irrigant and autoclaving regimes on the fracture resistance of rubber dam clamps
Authors: SUTTON J. , SAUNDERS W. P.
Published: September 2007

Rubber dam clamps are known to break during clinical use in endodontics. This in‐vitro study examined some of the variables which may contribute to the fracture. Stainless steel rubber dam clamps were subjected to various cleaning and autoclaving regimes and exposure to various solutions of sodium hypochlorite (NaOCl). Each clamp was examined after four cycles of cleaning and exposure to NaOCl. During environmental exposure to NaOCl, the clamp was stressed over a perspex rod to simulate placement onto the crown of a tooth. Clamps were examined after each test cycle visually and microscopically, or immediately after breakage. Results suggested that the fractures were because of a stress corrosion cracking phenomenon. There was evidence of intergranular and transgranular cracking of the metal. Corrosion spots were seen on the surface of the clamps and fracture occurred mainly through these spots. A number of recommendations to reduce breakage of clamps have been suggested.
Electronic length measurement using small and large files in enlarged canals
Authors: NGUYEN H. Q. , KAUFMAN A. Y. , KOMOROWSKI R. C. , FRIEDMAN S.
Published: September 2007

Electronic apex locators are frequently used attached to a small size endodontic file; however, the effect on the measurement of the relative diameters of the file and the root canal has not been clarified. In this study, the length of enlarged canals was measured using small size files and files matching the canal diameter to observe a possible discrepancy. The accuracy of electronic length control during canal preparation with rotary files was also assessed. The root canals in 21 extracted, single rooted teeth were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an alginate mold. The initial canal length (IL) was measured with the Root ZX apex locator by negotiating a size 10 file to the apical constriction. The canal was enlarged to size 60 with rotary files while the length was continuously controlled with the apex locator. Then, the final length measurements were obtained with a size 10 file and a size 60 file (FL‐10 and FL‐60, respectively). The average values of IL, FL‐10 and FL‐60 were calculated and compared using Repeated Measures Analysis of Variance followed by Tukey's Studentized Range test (P < 0.05). Using composite resin, the size 60 files were secured at the FL‐60 length, the teeth were removed from the alginate mold, stained with Picroformal DI Buoin stain and the position of the file tip was observed histomorphometrically after the apical 4 mm of the canal was exposed by grinding the buccal aspect of the root. The IL was 0.45 mm shorter than AL (P < 0.05). The differences between FL‐10, FL‐60 and IL were not statistically significant. Histomorphometrically, the apical constriction was absent in all the teeth, but the file tips were confined within the root. This study concluded that the Root ZX indicated the location of an apical constriction even when the anatomic constriction was eliminated. In the enlarged canals, length measurements obtained with small and large size files were comparable.
Distributed collaboration activities in a blended learning scenario and the effects on learning performance
Authors: Gerber M. , Grund S. , Grote G.
Published: September 2007

Abstract  The aim of this study was to investigate the nature of tutor and student online communication and collaboration activities in a blended learning course. The hypothesis that these activities are related to student learning performance (exam results) was tested based on the number of messages posted, as well as the nature of these messages (type of content transmitted in terms of course content‐related, interpersonal and organizational activities). Descriptive results show that tutors were mainly involved in organizational tasks, whereas students communicated mostly at content‐related and interpersonal levels. Student performance was not related to the quantity of tutors' activity, but to the quantity of students' activity. Closer examination of the nature of different activities showed that not only tutors' interpersonal, but also students' own content‐related and interpersonal messages had an impact on students' learning performance. This study raises the possibility that the nature of messages is more important than their quantity. It calls into question former research, which has indicated the importance of the amount of activity while mostly neglecting to discriminate between the differences in nature of activities and which has based its findings almost entirely on subjective ratings for both activities and performance. Implications for evaluation of activities and design of personal support are discussed.
Incidence of hepatocellular carcinoma among individuals with hepatitis B virus infection identified using an automated data algorithm
Authors: Yood M. Ulcickas , Quesenberry C. P. , Guo D. , Wells K. , Shan J. , Sanders L. , Skovron M. L. , Iloeje U. , Caldwell C. , Manos M. M.
Published: September 2007

Summary.  The purpose of this study was to develop an algorithm for identifying patients with chronic hepatitis B virus (HBV) using automated data sources from two US health systems and evaluate the algorithm’s performance by quantifying the incidence of hepatocellular carcinoma (HCC) among chronic HBV patients. To allow comparisons with estimates from automated databases that may not contain all data elements used in this algorithm, we created three definitions of chronic HBV infection and used these definitions to create three overlapping cohorts. We compared the incidence of HCC in each cohort with the incidence of HCC in a matched general population comparison cohort with no evidence of HBV. Patients who met the most stringent criteria for chronic HBV infection (based on the standard definition of 6 months of infection using repeat laboratory tests and record review) were 146 times more likely to develop HCC than matched comparison patients (adjusted hazard ratio = 146.5, 95% CI: 74.0–289.8). Those not meeting the stringent criteria, but who met the criterion of at least one positive hepatitis B surface antigen test were 30 times more likely to develop HCC than comparison patients (adjusted hazard ratio = 29.8, 95% CI: 16.5–53.6). Finally, patients who met the criterion based on at least one HBV diagnosis were 38 times more likely to develop HCC than matched comparison patients (adjusted hazard ratio = 37.8, 95% CI: 25.9–55.1). The magnitude of the relative increase in HCC risk seen using different criteria used to define HBV infection indicate that these automated data algorithms can identify patients with chronic HBV infection.
Exacerbation of chronic hepatitis B infection after delivery
Authors: Ter Borg M. J. , Leemans W. F. , De Man R. A. , Janssen H. L. A.
Published: September 2007

Summary.  During pregnancy several alterations in the immune status allow mothers to tolerate the genetically different foetal tissues. We investigated the evolution of liver disease during and after pregnancy in chronic hepatitis B patients. Between 1998 and 2006 there were 38 pregnancies in 31 chronic hepatitis B ‘s’ antigen‐positive women at our liver unit. Twenty‐four subjects (63%) were hepatitis B ‘e’ antigen (HBeAg)‐positive, 14 (37%) HBeAg‐negative. In 13 pregnancies (34%), lamivudine therapy was started during the last trimester of pregnancy to lower hepatitis B virus (HBV) DNA levels to reduce the risk of vertical transmission. A significant increase in liver disease activity after pregnancy, defined as a three times increase in alanine aminotransferase (ALT) within 6 months after delivery, occurred in 17 of 38 patients (45%). In those treated with lamivudine during the last trimester of pregnancy, this occurred in even 8/13 patients (62%). Prediction during pregnancy of these exacerbations was not possible using HBV DNA, ALT level, HBeAg status or any other characteristic. The median maximal ALT of these exacerbations was 4.0 × ULN and none led to decompensated liver disease. In conclusion, a significant increase in liver inflammation occurs often after pregnancy. This may be due to a reactivation of the immune system after delivery. Based on our data we recommend monitoring closely and if necessary treating women with chronic HBV shortly after delivery.
Lamivudine prevents reactivation of hepatitis B and reduces mortality in immunosuppressed patients: systematic review and meta‐analysis
Authors: Katz L. H. , Fraser A. , Gafter‐Gvili A. , Leibovici L. , Tur‐Kaspa R.
Published: September 2007

Summary.  To assess the effects of prophylactic lamivudine on reactivation and mortality following immunosuppressive therapy in hepatitis B surface antigen (HBsAg)‐positive patients, we performed a meta‐analysis. Systematic review and meta‐analysis of randomized and nonrandomized prospective controlled trials and retrospective comparative case series were identified through The Cochrane Hepato‐Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and LILACS. The primary outcomes were virological reactivation, clinical reactivation and mortality. Secondary outcomes included hepatitis B virus (HBV)‐related mortality, liver histology, discontinuation or disruption of immunosuppressive therapy, lamivudine‐resistant HBV strains and adverse events. A total of 21 studies were included, two of which were randomized controlled trials. Clinical and virological reactivation were significantly reduced in the lamivudine group [odds ratio (OR) 0.09; 95% confidence interval (CI) 0.05–0.15 and OR 0.04; 95% CI 0.01–0.14 respectively]. All‐cause mortality was significantly reduced in the lamivudine group (OR 0.36; 95% CI 0.23–0.56) which translates to only 11 patients who need to be treated to prevent one death. Lamivudine significantly reduced HBV‐related mortality, and discontinuations or disruptions of the immunosuppressive treatment. No adverse effects of lamivudine were recorded, and resistance to lamivudine occurred in low rates. We demonstrated a clear benefit of lamivudine in terms of clinical and virological HBV reactivation, overall mortality, HBV‐related mortality and interruptions or discontinuations in the immunosuppressive treatment. Lamivudine should be administered prophylactically to HBsAg‐positive patients who are about to receive immunosuppressive therapy.
Alternate SlyA and H‐NS nucleoprotein complexes control hlyE expression in Escherichia coli K‐12
Authors: Lithgow James K. , Haider Fouzia , Roberts Ian S. , Green Jeffrey
Published: September 2007

Haemolysin E is a cytolytic pore‐forming toxin found in several Escherichia coli and Salmonella enterica strains. Expression of hlyE is repressed by the global regulator H‐NS (histone‐like nucleoid structuring protein), but can be activated by the regulator SlyA. Expression of a chromosomal hlyE–lacZ fusion in an E. coli slyA mutant was reduced to 60% of the wild‐type level confirming a positive role for SlyA. DNase I footprint analysis revealed the presence of two separate SlyA binding sites, one located upstream, the other downstream of the hlyE transcriptional start site. These sites overlap AT‐rich H‐NS binding sites. Footprint and gel shift data showed that whereas H‐NS prevented binding of RNA polymerase (RNAP) at the hlyE promoter (PhlyE), SlyA allowed binding of RNAP, but inhibited binding of H‐NS. Accordingly, in vitro transcription analyses showed that addition of SlyA protein relieved H‐NS‐mediated repression of hlyE. Based on these observations a model for SlyA/H‐NS regulation of hlyE expression is proposed in which the relative concentrations of SlyA and H‐NS govern the nature of the nucleoprotein complexes formed at PhlyE. When H‐NS is dominant RNAP binding is inhibited and hlyE expression is silenced; when SlyA is dominant H‐NS binding is inhibited allowing RNAP access to the promoter facilitating hlyE transcription.
Assessment of potential risk factors associated with ischaemic colitis
Authors: Chang L. , Kahler K. H. , Sarawate C. , Quimbo R. , Kralstein J.
Published: September 2007

Abstract  Ischaemic colitis (IC) has been associated with a number of diverse disorders and risk factors, including irritable bowel syndrome (IBS) and constipation. We sought to assess, through a large‐scale population study, the potential risk factors associated with IC. Patients with IC and matched controls without IC were identified using the medical and pharmacy claims data from the HealthCore Managed Care Database from 1st January 2000 to 31st May 2005. A multivariate conditional logistic regression model was developed to identify significant risk factors of IC. Interactions of age, sex, prior IBS diagnosis, and prior constipation diagnosis were further evaluated. We identified 1754 patients with IC and 6970 non‐IC controls; 64% were women, and mean ages were 63 and 62 years respectively. The final parsimonious model comprised 19 independent variables associated with increased risk for IC including shock, dysentery, bloating, IBS, colon carcinoma, constipation, cardiovascular disease, dyspepsia, abdominal, aortic, or cardiovascular surgery, 12‐month laxative, H2 receptor blocker and oral contraceptive use. A significant interaction was observed between age and prior IBS on risk for IC. In conclusion, multiple risk factors for IC were identified and we confirmed that patients with IBS or constipation are at greater risk for IC.
Routine antenatal anti‐D prophylaxis and patient compliance with the two‐dose regimen
Authors: Chaffe B. , Ford J. , Bills V.
Published: September 2007

summary The aim of this study was to determine the compliance rates for women being offered routine antenatal anti‐D prophylaxis in two obstetric units in the UK. Haemolytic disease of the newborn (HDN) is a potentially serious condition that can result in substantial morbidity and sometimes death. Current guidelines recommend that 500 IU anti‐D immunoglobulin G (IgG) should be offered to all non‐sensitized RhD‐negative women at 28 and 34 weeks’ gestation in order to prevent the risk of RhD sensitization in pregnancy. Implementing guidance, however, remains a challenge. We conducted a retrospective audit of 207 RhD‐negative, non‐sensitized pregnant women attending obstetric units during 2004 to assess compliance with national guidance on the provision of antenatal anti‐D prophylaxis. Informed consent for routine antenatal anti‐D prophylaxis was documented for 185 of these women. In total, 86·5% of women received the two doses of anti‐D IgG. The majority of women received their first and second doses within 1 week of 28 and 34 weeks’ gestation (87·0 and 86·0%, respectively). Accurate records of prophylactic anti‐D IgG were maintained and updated. This audit demonstrates that the level of patient compliance with the two‐dose regimen was high.
The systematic monitoring of transfusion microbiology test kit performance
Authors: Nightingale M. J. , Ramskill S. , Newham J. , Kitchen A. , Bukasa A. , Wenham D. , Reeves I.
Published: September 2007

summary The Transfusion Microbiology Test Systems Monitoring Group (TMTSMG) was established as a National Blood Service (NBS) working group to monitor the performance of the microbiology screening assays used within the NBS Testing Laboratories. The group’s primary objective was to ensure that technical performance (especially sensitivity, specificity and wastage) remains consistent with that established during validation. This includes the identification and investigation of significant variation in performance and any untoward incidents. The group is also responsible for optimizing transfusion microbiology working practice across the NBS through nationally agreed standards and procedures. Over the past 9 years, a total of 44 assays from 15 suppliers have been monitored. Five assays have been withdrawn from use as a result of identified poor performance; two hepatitis B virus surface antigen assays owing to poor sensitivity, two syphilis agglutination assays with nonspecific (false) reactive rates sustained above contract limits and one human cytomegalovirus antibody assay that persistently failed the manufacturer’s quality control criteria. This approach has enabled the differentiation of genuine kit performance issues from ‘natural variation’ in kit performance, and local instrumentation or training issues. The NBS has been able to address the issues with suppliers much earlier and resolve minor issues before they became major problems. In addition, a lot release system has been developed and implemented, comprising a formal, centralized initial scientific assessment of each new manufacturer’s lot, followed by ‘delivery acceptance’ testing at each site. This system helps to ensure that the evaluated minimum sensitivity and specificity of the assays is maintained from ‘lot to lot’.
Predictable and avoidable human errors in phlebotomy area – an exclusive analysis from a tertiary health care system blood bank
Authors: Pandey P. , Chaudhary R. , Tondon R. , Khetan D.
Published: September 2007

summary Error is a direct reflection of system deficiency. Errors occurring in the phlebotomy area are grossly unreported. Though most of these errors does not lead to catastrophic outcome yet indicate system failure. The aim of the study was to identify errors that took place in phlebotomy area, analysing and classifying them. A prospective audit was conducted during an observational period of 8 months, in an overall cohort of 11 260 donors. The incidence of errors was 3·1%. Fifty‐five percent errors were technical and remaining 44·9% were clerical. Of all the technical errors, 57·7% were classified as minor, whereas remaining 42·3% were of major category. Similarly, majority of clerical errors (89·9%) were of minor category. The trained staff accounted for all major events (27·8%). In the minor category, technical errors (73·2%) were more commonly done by trained staff, whereas for clerical errors (58·5%), newly recruited staff was responsible. Errors in phlebotomy area are benign but can compromise donor safety. The study helped to develop a consistent and straightforward classification system for errors and to reduce them by basic interventions. Errors committed mostly by our trained staff indicate the need of regular competency testing and an active system for detection of these deviations.
The Role of the Endometrium in Endocrine Regulation of the Animal Oestrous Cycle
Authors: Krzymowski T , Stefańczyk‐Krzymowska S
Published: September 2007

Contents

A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows:

1. The transfer of prostaglandin F2α(PGF2α) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways.

2. The system of retrograde transfer of PGs enables PGF2αand PGE2to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF2α, together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE2together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy.

3. In days 10–12 of the cycle, the blood flow in the uterus decreases by 60–70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences.

4. The pulsatile elevations in PGF2αconcentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF2αsynthesis as suggested in numerous studies. They are the effect of excretion of PGF2αand its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates.