bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant allelochemicals differentially regulate Helicoverpa zea cytochrome P450 genes
Authors: Li Xianchun , Berenbaum May R. , Schuler Mary A. 
Published: March 2003

AbstractFour cytochrome P450 genes, CYP6B8, CYP6B9, CYP6B27 and CYP6B28, exist in the Helicoverpa zea genome as two pairs of paralogs that evolved from gene duplication and 5′‐polar gene conversion events. RT‐PCR gel blot analyses have shown that all of these genes are expressed constitutively in midguts of all larval instars, suggesting that they have primary roles in the detoxification of plant allelochemicals. Among these, CYP6B9 is expressed only in midgut tissue whereas its paralog, CYP6B27, is expressed primarily in midgut and secondarily in fat body and ovary. CYP6B28 is expressed in midgut, fat body and, to lesser extents in ovary and integument whereas its paralog, CYP6B8, is expressed in midgut and to some extent in fat body. Comparison of the expression levels induced by eight plant allelochemicals, one drug (phenobarbital), and an insecticide (α‐cypermethrin) indicates that, for the most part, the four P450s respond individually to these inducers, with all four induced strongly by chlorogenic acid, a shikimate pathway intermediate and a lignin biosynthesis intermediate present in a wide variety of plants, and indole‐3‐carbinol, a glucobrassicin breakdown product present in the Brassicaceae. The multiple levels at which these P450 genes are apparently diverging (e.g. transcriptional responses, protein sequences) support the suggestion that gene conversion events facilitate gene evolution by allowing duplicated copies greater time to acquire selectable differences in both coding and promoter sequences.
Comparison of EST libraries from seven beetle species: towards a framework for phylogenomics of the Coleoptera
Authors: Theodorides K. , De Riva A. , Gómez‐Zurita J. , Foster P. G. , Vogler A. P. 
Published: March 2003

AbstractRelatively little is known about Coleoptera genes and genomes and how these compare in different taxa. We describe here the construction, DNA sequencing and sequence comparisons of cDNA libraries from seven beetle species. A total of 6717 bacterial colonies were screened for cDNA insert containing plasmids and 2784 size selected clones were 5′‐ and 3′‐end sequenced to produce 1620 assembled sequences. Similarity comparisons with existing protein sequence databases revealed that 65.1% had matches (E < 10−4) in other organisms, with greater numbers of matches in Drosophila melanogaster than Caenorhabditis elegans and Saccharomyces cerevisiae databases. tBlastX comparisons also revealed numerous similarity hits (E < 10−20) in intra‐ and interlibrary comparisons. These results show the potential of small cDNA libraries for discovery and comparative analysis of genes useful for phylogenomic and functional studies.
Endodontic retreatment decisions: no consensus
Authors: Aryanpour S. , Van Nieuwenhuysen J. ‐P. , D'Hoore W. 
Published: March 2003

Aim  The objectives of the present study were to: (i) evaluate the consensus, if any, amongst dental schools, students and their instructors managing the same clinical cases, all of which involved endodontically treated teeth; and (ii) determine the predominant proposed treatment option.Methodology  Final year students, endodontic staff members and instructors of 10 European dental schools were surveyed as decision makers. Fourteen different radiographic cases of root canal treated teeth accompanied by a short clinical history were presented to them in a uniform format. For each case the decision makers were requested to: (i) choose only one out of nine treatment alternatives proposed, from ‘no treatment’ to ‘extraction’ via ‘retreatment’ and ‘surgery’ (ii) assess on two 5‐point scales: the difficulty of making a decision, and the technical complexity of the retreatment procedure.Results  The results indicate wide inter‐ and also intra‐school disagreements in the clinical management of root canal treated teeth. Analysis of variance showed that the main source of variation was the ‘school effect’, explaining 1.8% (NS) to 18.6% (P< 0.0001) of the treatment variations. No other factor explained as much variance. Decision difficulty was moderately correlated to technical complexity (Pearsons' r ranging from 0.19 to 0.35, P< 0.0001).Conclusions  No clear consensus occurred amongst and within dental schools concerning the clinical management of the 14 cases. The lack of consensus amongst schools seems to be due mainly to chance or uncertainty, but can be partly explained by the ‘school effect’.
Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions
Authors: Weiger R. , Rosendahl R. , Löst C. 
Published: March 2003

Aim This prospective clinical study explored the influence of calcium hydroxide as an interappointment dressing on the healing of periapical lesions associated with pulpless teeth that had not been endodontically treated previously. This was achieved by comparing the prognosis after a two‐visit root canal treatment with that following a one‐visit treatment.Methodology Seventy‐three patients were recruited having one tooth with an endodontically induced lesion. Of these patients, 67 could be re‐examined. Calcium hydroxide was placed in the instrumented root canals of 31 teeth for at least one week and the treatment finished at the second visit. Thirty‐six teeth were root canal treated at one visit. The criteria for success were the absence of signs and symptoms indicating an acute phase of periapical periodontitis and radiographically a periodontal ligament space ofnormal width.Methods for event time analysis were used to evaluate and compare the prognosis of both treatment approaches.Results The probability that complete periapical healing will take place increased continuously with the length of the observation period. In both treatment groups the likelihood that the root canal treatment yields a success within an observation time of five years exceeded 90%. A statistically significant difference between the two treatment groups could not be detected.Conclusions From a microbiological perspective, one‐visit root canal treatment created favourable environmental conditions for periapical repair similar to the two‐visit therapy when calcium hydroxide was used as antimicrobial dressing. One‐visit root canal treatment is an acceptable alternative to two‐visit treatment for pulpless teeth associated with an endodontically induced lesion.
Root canal treatment in general practice in Sudan
Authors: Ahmed M. F. , Elseed A. I. , Ibrahim Y. E. 
Published: March 2003

AbstractAimThe aim of this study was to evaluate the practice and depth of knowledge of root canal treatment by dental practitioners in Khartoum, the capital city of Sudan, in order to improve the current status of endodontic therapy.MethodologyA questionnaire was posted to 55 registered dental practitioners. Completed questionnaires were analysed in term of simple summary statistics.ResultsA total of fifty‐two (95%) practitioners responded. Eighty‐five per cent of the respondents indicated that they performed root canal treatment for their patients. Of these, 84% included molars in their activity. Amongst those who carried out root canal treatment, only one practitioner used rubber dam for isolation, whilst the remainder used cotton wool rolls. The majority of respondents (80%) used hydrogen peroxide to irrigate canals during treatment. Three‐quarters of practitioners used formocresol as an interappointment medicament. The stepback preparation technique was the method of choice for 98% of respondents. All practitioners used hand instruments to prepare root canals and all used gutta‐percha for obturation; three‐quarters of them used cold lateral condensation for all or some cases. The average number of radiographs routinely taken for root canal treatment was three. Only 73% used radiographs for measuring the working length. Ninety‐five per cent of respondents indicated that they usually completed a root filling in three or more visits. Three‐quarters of practitioners restored the teeth permanently immediately after the obturation and one‐quarter preferred waiting for 1 or 2 weeks.ConclusionsIn Sudan, there are no dental practices limited to endodontics and no postgraduate training programmes. This survey shows the importance of establishing higher specialist training or continuing dental education for practitioners to update their knowledge.
Use of rubber dam and irrigant selection in UK general dental practice
Authors: Whitworth J. M. , Seccombe G. V. , Shoker K. , Steele J. G. 
Published: March 2003

AbstractAimTo evaluate factors which influence rubber dam use and irrigant selection in UK National Health Service (NHS) endodontics.MethodologyA postal survey was conducted amongst two age cohorts of dentists, representing all of the 1970–73 (older) and 1990–93 (younger) graduates of two northern English dental schools (n = 643). Key and supplementary questions were posed on levels of rubber dam use, irrigant selection, and factors influencing practice in NHS endodontics. After manual checking, validated (dual) entry of responses was made to a flat ASCII data file before analysis with SPSS software. The threshold for statistical significance was set at the 95% probability level.ResultsEighty‐five per cent of the valid sample responded to the questionnaire. Regardless of age and qualifying school, less than one‐fifth of dentists always or frequently used rubber dam, whilst 60% never used it. Qualifying school had a significant influence on rubber dam use, whilst age had a variable influence. Major disincentives to the use of rubber dam included the perception that patients do not like it, that the NHS fee was inadequate to justify its use, that it took too long to apply, and that dentists had received inadequate training. Frequent users of rubber dam were significantly less likely to cite these disincentives than nonusers. Overall, local anaesthetic solution was the most common endodontic irrigant. Irrigant choice was strongly linked to rubber dam use, and to graduation cohort. Seventy‐one per cent of rubber dam users irrigated with sodium hypochlorite, compared with only 38% of nonusers. This pattern was reversed for local anaesthetic irrigation. Younger graduates were significantly more likely to irrigate with local anaesthetic solution than their older counterparts, and the younger graduates of one school showed a highly significant increase in the use of chlorhexidine.Conclusions1) The majority of UK Health Service dentists never use rubber dam isolation in endodontic treatment. 2) Qualifying school has a significant impact on rubber dam use, and irrigant selection. 3) Use of rubber dam has a significant association with irrigant choice in endodontics.
The efficacy of gutta‐percha removal using ProFiles
Authors: Ferreira J. J. , Rhodes J. S. , Pitt Ford T. R. 
Published: March 2003

AbstractAimThe purpose of this study was to compare the efficacy in vitro of gutta‐percha removal from obturated root canals using ProFiles.MethodologyForty‐eight human root canals with curvatures ranging between 25 and 45° were instrumented by a standardized method to an apical ISO size 30 and 0.04 taper. They were obturated with vertically condensed gutta‐percha. Retreatment was performed with the following techniques: K‐Flexofiles with chloroform; Hedstrom files with chloroform; ProFiles 0.04 taper with chloroform; ProFiles 0.04 taper alone. The time for each method was measured. A microfocal macroradiographic technique was used to evaluate the amount of debris remaining within the root canals after the retreatment procedure. Roots were divided into apical, middle and coronal parts and scored on a scale of 0 (no debris) to 3 (>50% of walls covered with debris) by trained observers on two separate occasions.ResultsThe scores for debris remaining within root canals for K‐Flexofiles with chloroform and ProFiles with chloroform were the lowest and not significantly different at all three levels of the roots examined (P > 0.05), and Hedstrom files with chloroform and ProFiles with chloroform were not significantly different in the apical part. In general, coronal parts were cleaner than apical parts. The difference in scores at the three levels between ProFiles with chloroform and ProFiles alone were each significant (P < 0.01). Instrumentation using ProFiles with chloroform (mean 6.42 min) was significantly faster than using hand files (mean 11.67 min) (P < 0.01).ConclusionThe results indicated that ProFiles or hand files with chloroform produced similarly clean canals, but that ProFiles were faster.
A methodology for quantitative evaluation of root canal instrumentation using microcomputed tomography
Authors: Bergmans L. , Van Cleynenbreugel J. , Wevers M. , Lambrechts P. 
Published: March 2003

AbstractAimThe aim of this paper was to present an objective methodology for quantitative evaluation of root canal instrumentation using microcomputer tomography, together with developed software based on a constructed mathematical model.MethodologyA desktop X‐ray micro‐CT scanner (SkyScan 1072) was used to provide data sets of an extracted mandibular molar before and after instrumentation (ProFile 0.04 Taper instruments, Dentsply Maillefer, Ballaigues, Switzerland) that were stored for later use by software. A volume visualization package (T3D) was applied to obtain 3D renderings of the molar to illustrate the qualitative visualization capacity. Next, medical image volume fusion software was used to allow alignment of pre and post image volumes. Finally, software was developed to make quantitative measurements and to provide additional qualitative information on the registered image volumes. This procedure implemented a true 3D mathematical model for quantification of instrumentation effects. Using a local co‐ordinate frame, perpendicular reslices were made at five different levels within the mesio‐buccal canal to evaluate transportation and centring ability.ResultsAt first accurate and detailed 3D renderings were obtained. The general and local canal shape before and after preparation could visually be examined in 360° rotation. Numerical values were obtained for volume, volume changes and transportation. Centring ability was calculated by centring ratio and centre movement.ConclusionsThis methodology is a new and objective way for quantitative evaluation of root canal instrumentation using microcomputer tomography and dedicated software.
Root canal treatment in an unusual maxillary first molar: a case report
Authors: Fava L. R. G. 
Published: March 2003

AbstractAimThe aim of this clinical article is to describe the unusual anatomy that was detected in a maxillary first molar during routine endodontic treatment.SummarySuccess in root canal treatment is achieved after thorough cleaning and shaping followed by the complete obturation of the root canal system. Such treatment may be performed in root canal systems that do not comply with the normal anatomical features described in standard textbooks. The present case describes root canal treatment in a maxillary first molar with two roots and a type IV canal configuration in the buccal root.Key learning points

Careful examination of radiographs and the internal anatomy of teeth is essential.
Root canal treatment is likely to fail if the entire system is not debrided and filled.
Anatomic variations can occur in any tooth.
Relationship between number of proximal contacts and survival of root canal treated teeth
Authors: Caplan D. J. , Kolker J. , Rivera E. M. , Walton R. E. 
Published: March 2003

AbstractAim The present study tested the hypothesis that having two proximal contacts (PCs) at access is associated with improved survival of root canal treated (RCT) teeth, controlling for important presenting conditions, endodontic variables and restorative factors.Methodology A treatment database at the University of Iowa College of Dentistry was used to identify permanent teeth undergoing obturation between 1 July 1985 and 31 December 1987. The list was restricted to teeth of patients with at least one dental visit in each two‐year interval from 1985 to 1996, and a simple random sample of 280 patients (n = 400 teeth) was selected. Dental charts, radiographs, and computerized databases were examined to ascertain variables of interest and to verify study inclusion criteria. Kaplan–Meier survival estimates were generated for the 221 teeth satisfying study inclusion criteria. Multivariate Cox models were developed, with standard errors adjusted to account for clustering of teeth within patients.Results The final Cox model showed that teeth with ≤1 PC at access were lost at a rate three times that of teeth with 2 PCs (hazard ratio = 3.1; 95% confidence interval = 1.9–5.1), controlling for tooth type, presence of radiographic caries at access, and presence of a crown before or after obturation.Conclusions Because RCT teeth with two PCs at access experienced substantially better survival than teeth with fewer than two PCs, the influence of PCs on prognosis should be recognized during treatment planning. Future research should employ prospective study designs, capture additional variables, and provide data to support endodontic treatment decisions.
A comparison of the shaping characteristics of two nickel–titanium endodontic hand instruments
Authors: Dobó‐Nagy C. , Serbán T. , Szabó J. , Nagy G. , Madléna M. 
Published: March 2003

AbstractAim The purpose of this study was to compare the shaping characteristics of Ni–Ti K‐files and Ni–Ti S‐files manipulated by hand.Methodology A total of 60 extracted human roots were embedded in resin blocks. The embedded roots were divided into three groups: (i) roots with straight; (ii) apically curved; and (iii) continuously curved canals. Each of the three groups was randomly divided into two subgroups; one subgroup in each group was prepared with Ni–Ti K‐files and the other with Ni–Ti S‐files. The files were used with a step‐back technique and enlarged so that the master apical file was size 30, and the canals were stepped back to size 40. The performance of the files was assessed by the superimposition of projected radiographs taken in bucco‐lingual and mesio‐distal directions before and after the preparation. The results were analysed statistically using analysis of covariance and Duncan’s multiple range test.Results Although canal preparation using Ni–Ti K‐files was quicker, there were no statistically significant differences between file types. The Ni–Ti S‐file removed significantly more material at the most coronal level (P < 0.05). There were minor differences between instruments at the apical level. Only in the proximal view of apically curved canals prepared with Ni–Ti S‐files was significantly more dentine removed from the outer aspect of the curvature (P < 0.05). At the middle level (wide danger zone) the Ni–Ti S‐files removed more dentine from the inner aspect of the curvature in those roots with apically curved canals.Conclusions Under the conditions of this study, preparation with Ni–Ti K‐files produced more appropriate shapes in roots with apically curved canals than Ni–Ti S‐files.
Mechanisms involved in the resistance of Enterococcus faecalis to calcium hydroxide
Authors: Evans M. , Davies J. K. , Sundqvist G. , Figdor D. 
Published: March 2003

AbstractAim This study sought to clarify the mechanisms that enable E. faecalis to survive the high pH of calcium hydroxide.Methodology E. faecalis strain JH2‐2 was exposed to sublethal concentrations of calcium hydroxide, with and without various pretreatments. Blocking agents were added to determine the role of stress‐induced protein synthesis and the cell wall‐associated proton pump.Results E. faecalis was resistant to calcium hydroxide at a pH of 11.1, but not pH 11.5. Pre‐treatment with calcium hydroxide pH 10.3 induced no tolerance to further exposure at pH 11.5. No difference in cell survival was observed when protein synthesis was blocked during stress induction, however, addition of a proton pump inhibitor resulted in a dramatic reduction of cell viability of E. faecalis in calcium hydroxide.Conclusions Survival of E. faecalis in calcium hydroxide appears to be unrelated to stress induced protein synthesis, but a functioning proton pump is critical for survival of E. faecalis at high pH.
To store or mature spermatozoa? The primary role of the epididymis
Authors: Jones  
Published: March 2003

The function of the epididymis is considered in the context that it is necessary to transport spermatozoa for internal fertilization, but is also an adaptation involved in the competition between males to achieve paternity. Post‐testicular sperm maturation and storage occur in lower vertebrates, such as the chondrichthyes, in which sperm storage is essential due to the slow rate of spermatogenesis. These roles persist in higher vertebrates, including mammals. However, they are less important in certain birds, in which the rate of sperm production by the testes is sufficient to supply enough spermatozoa to cope with the demands of a competitive mating system.There is no evidence for mammals, other than humans, that spermatozoa can achieve the capacity to fertilize an ovum without passing through some of the proximal epididymis. Storage of spermatozoa in the epididymis is probably not essential for a male to achieve conception in a protected mating system, but is very important in a competitive mating system. There is some variation between species in the magnitude of the epididymal storage region. This is related to the descent of the epididymides (and testes) into a scrotal sac in some species and/or the demands of the mating system in other species. The claims that humans are not dependent on post‐testicular sperm maturation and storage need to be qualified, as they are based on studies of abnormal tracts and tests of fertility which are not rigorous. Nevertheless, the claims are of considerable clinical significance and may indicate that humans are less dependent on post‐testicular sperm maturation and storage than other mammals. This may be an adaptation of the testes and epididymides to the scrotal conditions of modern man or a response to changing environmental factors.