bluuebunny/crossref_metadata_2025 huggingface dataset:
Understanding the successful adoption and use of IS/IT in SMEs: an explanation from Portuguese manufacturing industries
Authors: Caldeira Mário M. , Ward John M.
Published: March 2003

Abstract. The objectives of the research were to identify factors enabling or inhibiting the adoption and use of information systems and technology (IS/IT) in Portuguese manufacturing small and medium‐sized enterprises (SMEs) and understand how these factors interrelate in determining relative success in the adoption and use of IS/IT. This research elicited factors from previous quantitative and qualitative research, which had been shown to influence IS/IT adoption in SMEs in other contexts. A strategic change framework was used to structure the factors and ensure that comprehensive evidence about their nature and effects could be obtained in the empirical research. Further factors were identified by initial fieldwork, before carrying out 12 in‐depth case studies, across a range of situations – different industries, different levels of adoption and a range of degrees of success in IS/IT use. The pattern that emerged from the analysis of the data shows that certain factor combinations and relationships appear to determine the relative degrees of IS/IT success across the firms. This pattern can also be explained by interpreting the roles and relationships of the key actors involved in the process of IS/IT adoption and use. Top management perspectives and attitudes towards IS/IT adoption and use play an important role in the development of internal IS/IT competencies and provide an important contribution to the development of a context that enables IS/IT success.
Evolutionary relationships among the Braconidae (Hymenoptera: Ichneumonoidea) inferred from partial 16S rDNA gene sequences
Authors: Dowton M. , Austin A. D. , Antolin M. F.
Published: March 2003

Phylogenetic relationships among the Braconidae were examined using homologous 16S rDNA gene sequence data. Analyses recovered the few well‐supported relationships evident in this family from morphological analyses, viz the monophyly of the microgastroid complex of subfamilies, the monophyly of the cyclostome complex of subfamilies (=braconoids), a sister‐group relationship between the Alysiinae and Opiinae, and a close relationship between the Helconinae and Blacinae. With respect to the braconoid complex of subfamilies, a sister‐group relationship was recovered between Aphidiinae and Mesostoinae, and a clade composed of Gnamptodontinae + Histeromerinae + Rhyssalinae + Aphidiinae +Mesostoinae was also recovered. The Doryctinae and Rogadinae sensu lato (s.l.) were generally not resolved as monophyletic. With respect to the helconoid complex of subfamilies, a sister‐group relationship was recovered between Sigalphinae and Agathidinae, whereas Neoneurinae fell out among other helconoid subfamilies. Other relationships among the helconoid subfamilies were unclear from these analyses. With respect to the microgastroid complex of subfamilies, our data conform to morphological estimates, recovering ((Microgastrinae+Miracinae)+Cardiochilinae)+Cheloninae. The topology of our trees suggests that the cyclostome subfamilies are a natural derived group, inferring that endoparasitism (not ectoparasitism) is the ancestral state for the Braconidae, unless all of the ectoparasitic ancestors of the helconoid+microgastroid subfamilies are now extinct.
Characterization of the Sialokinin I gene encoding the salivary vasodilator of the yellow fever mosquito, Aedes aegypti
Authors: Beerntsen B. T. , Champagne D. E. , Coleman J. L. , Campos Y. A. , James A. A.
Published: March 2003

The gene encoding sialokinin I, the principal vasodilatory peptide of Aedes aegypti, has been isolated and characterized. Degenerate oligonucleotide primers based on peptide amino acid sequence were used to amplify a gene fragment from messenger RNA (mRNA) isolated from female salivary glands. The amplification product was used to probe a salivary gland complementary DNA (cDNA) library, and a number of corresponding cDNAs were isolated and their primary sequence determined. Analysis of the conceptual translation product of a 406‐bp cDNA indicates that sialokinin I is expressed as a preprosialokinin and is subsequently post‐translationally processed to the active peptide. Northern analysis revealed a 490‐bp transcription product expressed exclusively in female salivary glands, and hybridization in situ of probes to RNA in whole tissues localized gene expression to the medial lobe of female salivary glands. Screening of an Ae. aegypti genomic library with the cDNA resulted in the isolation of a clone containing the gene, designated Sialokinin I (Sia I). Comparison of the cDNA with the genomic clone reveals two introns of 62 bp and 833 bp. Primer extension analysis showed that several transcription initiation sites are present. Southern analysis of genomic DNA shows that Sia I is most probably a single‐copy gene. Similarities of the Sia I gene product with other genes are confined to the region encoding the active decapeptide.
Intron insertion as a phylogenetic character: theengrailedhomeobox of Strepsiptera does not indicate affinity with Diptera
Authors: Rokas A. , Kathirithamby J. , Holland P. W. H.
Published: March 2003

The phylogenetic relationships of the order Strepsiptera are unclear. Affiliation to Coleoptera has been proposed, however this implies that dipteran halteres and strepsipteran haltere‐like organs evolved convergently. An alternative is a sister group relationship with Diptera. In this case, halteres could be homologous but a radical homeotic mutation may have switched their position to the Strepsipteran mesothorax. Ribosomal DNA sequence analysis has been used to support Dipteran affiliation, although this is controversial. Here we investigate the potential of an intron insertion site as a phylogenetic character. We find that theenhomeobox gene of the strepsipteranStichotrema dallatorreanumlacks a derived intron insertion shared by representatives of Diptera and Lepidoptera. We argue against a close affiliation between Strepsiptera and Diptera.
Cloning and expression of a novel juvenile hormone‐metabolizing epoxide hydrolase during larval–pupal metamorphosis of the cabbage looper, Trichoplusia ni
Authors: VanHook Harris S. , Thompson D. Marin , Linderman R. J. , Tomalski M. D. , Roe R. M.
Published: March 2003

A full‐length cDNA encoding for a microsomal juvenile hormone (JH)‐metabolizing epoxide hydrolase (TmEH‐1) was isolated from a cDNA library constructed from fat body of last stadium (wandering) cabbage loopers, Trichoplusia ni, at the exact developmental time of maximum JH epoxide hydrolase activity. TmEH‐1 was 1887 base pairs in lenght with a 1389 base pair open reading frame encoding 463 amino acids. Amino acid sequence analysis showed that TmEH‐1 was most similar to and contained the exact catalytic triad (Asp‐226, Glu‐403 and His‐430) found in microsomal epoxide hydrolases. TmEH‐1‐specific message was present along with JH III epoxide hydrolase activity in fat body in feeding (days 1 and 2) and wandering (day 3) larvae with the peak in message level preceding the peak in JH epoxide hydrolase activity by 1 day. When TmEH‐1 was expressed in baculovirus‐infected Spodoptera frugiperda cells, a 46,000 molecular weight protein appeared on SDS‐PAGE which corresponded to the predicted size coded by the TmEH‐1 message and which was positively correlated with increases in JH III epoxide hydrolase activity above that of wild‐type controls. In subcellular distribution studies, 58% of the juvenile hormone III epoxide hydrolase activity was in the insoluble fractions. Baculovirus expressed TmEH‐1 demonstrated a higher specific activity for JH III as compared to the general EH substrates, cis‐ and trans‐stibene oxide. Southern blot analyses suggested that multiple epoxide hydrolase genes are present in T. ni.
Cloning and analysis of a cecropin gene from the malaria vector mosquito, Anopheles gambiae
Authors: Vizioli J. , Bulet P. , Charlet M. , Lowenberger C. , Blass C. , Müller H.‐M. , Dimopoulos G. , Hoffmann J. , Kafatos F.C. , Richman A.
Published: March 2003

Parasites of the genus Plasmodium are transmitted to mammalian hosts by anopheline mosquitoes. Within the insect vector, parasite growth and development are potentially limited by antimicrobial defence molecules. Here, we describe the isolation of cDNA and genomic clones encoding a cecropin antibacterial peptide from the malaria vector mosquito Anopheles gambiae. The locus was mapped to polytene division 1C of the X chromosome. Cecropin RNA was induced by infection with bacteria and Plasmodium. RNA levels varied in different body parts of the adult mosquito. During development, cecropin expression was limited to the early pupal stage. The peptide was purified from both adult mosquitoes and cell culture supernatants. Anopheles gambiae synthetic cecropins displayed activity against Gram‐negative and Gram‐positive bacteria, filamentous fungi and yeasts.
Sperm‐mediated transformation of the honey bee, Apis mellifera
Authors: Robinson K. O. , Ferguson H. J. , Cobey S. , Vaessin H. , Smith B. H.
Published: March 2003

Our primary objective was to identify techniques to transform the genome of the honey bee (Apis mellifera) with foreign DNA constructs. The strategy we adopted was to linearize foreign DNA and introduce it with sperm during the instrumental insemination of virgin queen honey bees. We analysed extracts from larvae within the same cohort and isolated the predicted fragment by means of PCR amplification of genomic DNA. Larvae that carried the construct also expressed the introduced DNA. We propagated several transgenic lines for up to three generations, which demonstrates its heritability. Once carried by a queen, the construct can be detected in that queen’s larvae over several months. However, there was no evidence of integration of the construct, at least as determined by genomic Southern analysis. Nevertheless, this demonstrates the general viability of the technique for introduction of DNA, and it should be augmented by further use of transposable elements that enhance integration.
Amino acids in SRS1 and SRS6 are critical for furanocoumarin metabolism by CYP6B1v1, a cytochrome P450 monooxygenase
Authors: Chen J.‐S. , Berenbaum M. R. , Schuler M. A.
Published: March 2003

CYP6B1v1 is the principal cytochrome P450 monooxygenase (P450) that detoxifies dietary furanocoumarins in the guts of Papilio polyxenes, the black swallowtail caterpillar. Sequence alignments and structure comparisons of CYP6B1v1 with the mouse CYP2A5 and bacterial CYP102 proteins, which are also capable of metabolizing the linear furanocoumarin xanthotoxin (8‐methoxypsoralen), suggested that Phe116, His117, Val368 and Phe484 might be active site residues. In a homology model developed for CYP6B1v1, the side chains of Phe116 and His117 located in the B′‐C loop of SRS1 are predicted to be positioned above the haem plane, while the side chain of Phe484 located in SRS6 is predicted near the entrance of the catalytic pocket. Site‐directed mutagenesis of residues Phe116, His117 and Phe484 indicated that these residues represent several of those that determine this protein’s stability and substrate specificity. Whereas all aromatic mutants of Phe116 and Phe484 generated CO‐difference spectra with maxima at 450 nm indicative of correctly configured monooxygenases, aromatic mutants of Phe116 exhibited reduced reactivities toward some furanocoumarins and aromatic mutants of Phe484 eliminated all reactivities toward furanocoumarins. All single and double aliphatic mutants of Phe116, His117 and Phe484 and aromatic mutants of His117 generated carbon monoxide (CO) difference spectra with maxima at 420 nm (P420) indicative of incorrectly configured monooxygenases. These studies define residues Phe116, His117 and Phe484 as determinants of this insect P450’s catalytic site integrity and residues Phe116 and Phe484 as determinants of its substrate specificity. Conservation of Phe116 and His117 in an array of lepidopteran CYP6B proteins implies that these amino acids serve a similar function in other monooxygenases of the insect CYP6B subfamily.
Hemolin gene silencing by ds‐RNA injected into Cecropia pupae is lethal to next generation embryos
Authors: Bettencourt R. , Terenius O. , Faye I.
Published: March 2003

There is increasing evidence of an intimate connection between participants in the innate immune system and in development. Molecules involved in the determination of dorso‐ventral polarity in Drosophila have related counterparts in the signalling pathways for immune gene activation in both insects and mammals. Hemolin from the Giant silkmoth, Hyalophora cecropia, identified as a bacteria‐inducible molecule and a member of the immunoglobulin superfamily, is present as protein and transcripts in oocytes and embryos. We used RNA interference (RNAi) to investigate H. cecropia gene function in vivo and demonstrated that Hemolin is crucial for the normal development of embryos. When RNAi‐females were mated, no larvae emerged from their eggs and when dissected, the eggs revealed malformed embryos. Western blot analysis confirmed the lack of Hemolin gene products. We conclude that Hemolin is necessary for development, since the silencing of Hemolin gene expression leads to embryonic lethality.
Resistance‐associated point mutations of organophosphate insensitive acetylcholinesterase, in the olive fruit fly Bactrocera oleae
Authors: Vontas J. G. , Hejazi M. J. , Hawkes N. J. , Cosmidis N. , Loukas M. , Hemingway J.
Published: March 2003

A 2.2‐kb full length cDNA containing an ORF encoding a putative acetylcholinesterase (AChE) precursor of 673 amino acid residues was obtained by a combined degenerate PCR and RACE strategy from an organophosphate‐susceptible Bactrocera oleae strain. A comparison of cDNA sequences of individual insects from susceptible and resistant strains, coupled with an enzyme inhibition assay with omethoate, indicated a novel glycine‐serine substitution (G488S), at an amino acid residue which is highly conserved across species (G396 of Torpedocalifornica AChE), as a likely cause of AChE insensitivity. This mutation was also associated with a 35–40% reduction in AChE catalytic efficiency. The I199V substitution, which confers low levels of resistance in Drosophila, was also present in B. oleae (I214V) and in combination with G488S produced up to a 16‐fold decrease in insecticide sensitivity. This is the first agricultural pest where resistance has been associated with an alteration in AChE, which arises from point mutations located within the active site gorge of the enzyme.
Specific developmental gene silencing in the honey bee using a homeobox motif
Authors: Beye M. , Härtel S. , Hagen A. , Hasselmann M. , Omholt S. W.
Published: March 2003

Manipulating the expression of genes in species that are not currently used as genetic models will provide comparative insights into the evolution of gene functions. However the experimental tools in doing so are limited in species that have not served as models for genetic studies. We have examined the effects of double stranded RNA (dsRNA) in the honey bee, an insect with considerably basic scientific interest. dsRNA derived from a 300 bp stretch of the E30 homeobox motif was injected into honey bee embryos at the anterior pole in the preblastoderm stage. We found that the dsRNA fragment successfully disrupted the protein expression of the target gene throughout the whole embryo. The disruption caused deficient phenotypes similar to known loss of function mutants of Drosophila engrailed, whereas embryos injected with nonsense dsRNA showed no abnormalities. We show that the large size of the honey bee egg (D: 0.3 mm, L: 1.6 mm) and the long preblastoderm stage (11–12 h) can be exploited to generate embryos with partial disruption of gene function, which may provide an elegant alternative to classical chimeric analyses. This is the first report of targeted disruption of gene function in the honey bee, and the results prove that the chosen target gene is a functional ortholog to engrailed in Drosophila.
CYP6B cytochrome P450 monooxygenases from Papilio canadensis and Papilio glaucus: potential contributions of sequence divergence to host plant associations
Authors: Li W. , Petersen R. A. , Schuler M. A. , Berenbaum M. R.
Published: March 2003

Two groups of furanocoumarin‐inducible cytochrome P450 genes, the CYP6B4 group and the CYP6B17 group, characterized in two closely related tiger swallowtails, Papilio glaucus and Papilio canadensis, are induced to different extents, with generally higher levels of CYP6B transcripts in P. glaucus. To investigate the evolutionary history of these CYP6B genes in the context of their association with furanocoumarin detoxification, we isolated thirteen CYP6B genes from these species. Each of these genes contains an intron at a conserved position (1334 nucleotides from the translation start site), which varies in length due to three insertion/deletions. The proximal 5′ end flanking sequence from the transcription initiation site is highly conserved (91–98% nt identity). The sequence 5′ to −640 is significantly variable due largely to the presence of three insertion/deletions. The sequence at the 3′ end of this region contains a putative xenobiotic response element to xanthotoxin (XRE‐xan), important for basal and xanthotoxin‐inducible transcription of the P. polyxenes CYP6B1v3 gene, and multiple elements known to regulate vertebrate phase I and II promoters, including an XRE‐AhR (Xenobiotic Response Element to Aryl hydrocarbon Receptor), an OCT‐1 element (octamer protein binding site), an ARE (Antioxidant Response Element), an EcRE (Ecdysone Response Element), and an imperfect PXR (Pregnane X Receptor) responsive element (PRE). Our analyses of CYP6B genes in these two species indicate that these genes are in an early stage of divergence and that differential exposure of these two species to chemically distinct host plants resulting from geographical isolation has had functional impacts not only on the coding regions of these genes but also on their promoter regions. Thus, changes in P450 regulation as well as catalytic activity may play a role in the evolution of host plant associations in herbivorous insects.
Characterization of JNK‐like protein derived from a mosquito cell line, C6/36
Authors: Mizutani T. , Kobayashi M. , Eshita Y. , Inanami O. , Yamamori T. , Goto A. , Ako Y. , Miyoshi H. , Miyamoto H. , Kariwa H. , Kuwabara M. , Takashima I.
Published: March 2003

When Western blot analysis of heat‐killed bacteria‐ and lipopolysaccharide (LPS)‐treated Aedes albopictus mosquito cell line C6/36 was performed using antiphospholyrated c‐Jun amino‐terminal kinase (JNK) antibodies, approximately 46 kDa protein was clearly detected with a peak around 30 min. After the C6/36 cells were incubated at 45 °C in order to induce apoptosis, the 46 kDa protein continued to be detected for at least 3 h. The internalization of fluorescein‐labelled bacteria was inhibited by a JNK‐specific inhibitor SP600125, suggesting that phagocytosis involves the JNK signalling pathway in mosquito cells. Based on these results, we found one candidate for the nucleotide sequence of JNK (Ae‐JNK) from the C6/36 cells. This study is the first report regarding the mitogen‐activated protein kinase (MAPK) of mosquito.
Translation of both 5′TOP and non‐TOP host mRNAs continues into the late phase of Baculovirus infection
Authors: Van Oers M. M. , Doitsidou M. , Thomas A. A. M. , De Maagd R. A. , Vlak J. M.
Published: March 2003

Complete cDNA sequences were obtained for ribosomal protein (rp) L15 and eukaryotic initiation factor eIF2α from the lepidopteran insect Spodoptera frugiperda, and for elongation factor eEF2 from S. exigua. The presence of a 5′ terminal oligopyrimidine (TOP) tract classified the lepidopteran rpL15 transcript as a TOP mRNA. For eEF2, two types of transcripts were observed, one of which had a 5′TOP tract. The transcript levels for rpL15, eEF2 and eIF2α decreased following baculovirus infection. Polysome analysis showed that the corresponding mRNAs remained to be translated until at least 16 h post‐infection for both TOP and non‐TOP mRNAs. Baculovirus‐induced host shut‐off therefore appears to be regulated at the level of RNA abundance rather than at the translational level.
Study of the number of roots and canals in Senegalese first permanent mandibular molars
Authors: Sperber  , Moreau
Published: March 2003

A study of 480 extracted first permanent mandibular molars of the Oulof people of Senegal, West Africa, revealed 15 teeth with three roots (3.12%), and 120 teeth with four root canals (25%). An extra root correlated with a sextum lingual tubercle in 20% of cases. Analysis of the pulp chambers revealed a variety of rectangular shapes. Comparison of these anomalies with their incidence in other ethnic groups extends the range of incidence of three‐rooted first permanent mandibular molars in the Negroid race. This trait is described for only the second time in a Negroid population. The clinical consequences of root variation in root canal treatment are considered.
Cyclic fatigue of Profile rotary instruments after simulated clinical use
Authors: Yared G. M. , Dagher F. E. Bou , Machtou P.
Published: March 2003

Aim The purpose of this study was to evaluate cyclic fatigue of Profile Ni–Ti rotary instruments (PRIs) after dry heat sterilization and up to 10 times simulated clinical use.

Methodology Instruments of size 40–15 were used in a crown‐down technique. Three groups were included in this study. In groups 1 and 2, each set of instruments was used in five and 10 canals, respectively. Group 3 was the control group. NaOCl at a concentration of 2.5% was used as an irrigant. Each set of instruments was sterilized before each use.

Results The PRI size 40 demonstrated the lowest incidence of rotations to breakage. One‐way analysis of variance and Tukey’s HSD test showed statistically significant differences among different file sizes within each group.

Conclusions The results showed that dry heat sterilization and simulated clinical use in the presence of NaOCl did not lead to a decrease in the number of rotations to breakage of the files.
Contemporary treatment of the resorbed avulsed tooth: a case report
Authors: Pertl C. , Ebeleseder K. , Lorenzoni M. , Bantleon P. , Wegscheider W. A.
Published: March 2003

Case report This report describes the treatment sequence after traumatic loss of a maxillary central incisor in a 15‐year‐old patient. Following extraoralroot canal treatment and initially successful replantation, the case presented 9 years later with complete root resorption. After augmentation with an autologous mandibular corticocancellous graft, a dental implant was placed in a second stage surgery. The case highlights the challenge facing clinicians in providing the appropriate standard of care for today's treatment options.
Adaptation and sealability of two contemporary obturation techniques in the absence of the dentinal smear layer
Authors: Kytridou V. , Gutmann J. L. , Nunn M. H.
Published: March 2003

Kytridou V, Gutmann JL, Nunn MH. Adaptation and sealability of two contemporary obturation techniques in the absence of the dentinal smear layer. International Endodontic Journal, 32, 464–474 1999.

Aim The aim of this study was to evaluate the adaptation and short‐ and long‐term sealability of two different thermoplastic techniques — a core carrier technique, Thermafil; and a warm vertical continuous wave of compaction technique, System B.

Methodology Fifty‐one mesial roots of mandibular molars with separate canals, patent canal orifices and curvature greater than 15 degrees were cleaned and shaped with Orifice Shapers and ProFile.04/.06 taper Ni‐Ti rotary files using 5.25% NaOCl and 17% REDTA to a size 30.04 taper Profile at the apex to create a continuous tapered preparation. Canals were randomly obturated with Sealapex root canal sealer and either alpha‐phase gutta‐percha on a plastic Thermafil carrier, or nonstandardized beta‐phase gutta‐percha using the System B heat source. Proximal radiographs of roots were evaluated by three examiners based on established criteria for overall material adaptation, apical adaptation and filling material extrusion. Teeth were randomly separated into three groups of 17 each and placed in black India ink for 10 days, 24 h, or after 67 days storage in Hank’s Balanced Salt Solution. All roots were demineralized and rendered transparent. Three examiners evaluated the apical leakage by the linear measurement of dye penetration under the stereo‐microscope. The movement of filling material into canal irregularities was also evaluated.

Results Both obturation techniques were not significantly different in the overall canal obturation and in the apical third adaptation (P 0.05). Significantly more filling material extrusion beyond the apex was noted with the Thermafil technique (P 0.001). No significant difference was found amongst the 67‐day, 10‐day and 24h System B groups (P 0.05). The 67‐day Thermafil group showed significantly more leakage than the 10‐day and 24h Thermafil groups. There was a significant difference in the degree of leakage between the 67‐day Thermafil group and the 67‐day System B group (P 0.05), but not between the 10‐day and 24 h groups (P 0.05). Both obturation techniques produced substantial filling material movement into canal irregularities.

Conclusions It was concluded that Thermafil demonstrated more filling material extrusion beyond the apex and significantly more long‐term apical leakage.
Shaping ability of .04 and .06 taper ProFile rotary nickel–titanium instruments in simulated root canals
Authors: Bryant S. T. , Dummer P. M. H. , Pitoni C. , Bourba M. , Moghal S.
Published: March 2003

Aim The aim of this study was to determine the shaping ability of ProFile .04 and .06 taper rotary nickel–titanium instruments in simulated canals.

Methodology A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared using the ‘crown‐down’ approach recommended by the manufacturer. Pre‐operative pictures of each canal were recorded on optical discs using an image analysis package. The simulated canals were prepared and postoperative pictures superimposed on the original images.

Results No instrument fractures occurred and none deformed; none of the canals became blocked with debris. Change in working distance was, on average, 0.063 mm with 33 canals retaining the correct length. Overall, five zips (12.5%) were created and 24 (60%) canals demonstrated a widened area on the outer aspect of the canal between the end‐point and the curve. Two danger zones (5%) were created and two perforations but no ledges were found. Between canalshapes there were highly significant differences (P 0.0001) for the incidence of zips and elbows but not for the other aberrations. There were highly significant differences (P 0.0001) for the total width of the canals between the various canal shapes at the apex of the curve, the beginning of the curve and half way to the orifice, and a significant difference (P 0.05) at the end‐point. There were highly significant differences (P 0.0001) for the amount of resin removed from the outer aspect of the curve at the end‐point and at the beginning of the curve, and significant differences (P 0.05) at the apex of the curve and half way to the orifice. There were highly significant differences (P 0.0001) for the amount of resin removed from the inner aspect of the curve at the beginning of the curve and half way to the orifice. Overall, transportation was towards the outer aspect of the canal except at the beginning of the curve.

Conclusions Under the conditions of this study the combined use of .04 and .06 taper ProFile instruments was rapid, effective and produced good canal shapes except in those specimens with short curves that began near the end‐point.
Analysis of the healing response to gutta‐percha and Diaket when used as root‐end filling materials in periradicular surgery
Authors: Witherspoon D. E. , Gutmann J. L.
Published: March 2003

Witherspoon DE, Gutmann JL. Analysis of the healing response to gutta‐percha and Diaket when used as root‐end filling materials in periradicular surgery. International Endodontic Journal, 33, 37–45, 2000.

Aim  To analyse the healing response to gutta‐percha and Diaket when used as root‐end filling materials in periradicular surgery.

Methodology Periradicular surgery was completed using the mandibular second, third and fourth premolar teeth from nine male mongrel dogs. The six roots on one side of the mouth were randomly allocated to one of the following groups: group A: a resected root end and a burnished gutta‐percha root filling; group B: cavities were prepared to a depth of 4.0 mm, using ultrasonic root‐end preparation and filled with Diaket. The response was evaluated histologically at 55 (nine specimens) and 150 (three specimens) days post operatively.

Results  The data for the 55‐day period was analysed statistically using Wilcoxon's Signed Ranks test. No statistical analysis was carried out on the 150‐day group due to the small number of specimens. The level of significance was set at P <0.05. No statistical significance was observed in the healing response between Diaket and gutta‐percha in the following categories at 55 days: inflammatory response, angiogenesis, root‐end resorption, and cementum deposition. Statistically significant differences were observed in the healing categories: bone apposition (P <0.05) and periodontal ligament formation (P <0.05).

Conclusions  At both time intervals, Diaket had a better healing response that was characterized by hard tissue formation adjacent to the root‐end filling material bordered by occasional multinucleated giant cells. The nature of both the hard tissue formation and the adjacent cells, however, remains undetermined. Diaket displayed the best healing of either material used in this study.
The effects of Ledermix paste on discolouration of immature teeth
Authors: Kim S. T. , Abbott P. V. , McGinley P.
Published: March 2003

Aim

The aims of this study were to: (i) investigate the effects of Ledermix paste as an intracanal medicament on discolouration of immature teeth, (ii) examine whether the discolouring effects were related to the method of application, (iii) examine the effects of sunlight upon discolouration of immature teeth and (iv) compare the degree of discolouration between mature and immature teeth.

Methodology

The root canals of 45 immature extracted human teeth were prepared and filled with either Ledermix paste, calcium hydroxide [Ca(OH)2], or saline. In group 1, Ledermix paste was only placed apical to the cemento‐enamel junction (CEJ) whilst in groups 2 and 3, the paste filled the entire pulp chamber and the root canals. In group 4, Ca(OH)2 paste and in group 5, saline (control) were allowed to fill the pulp chamber and the root canals. Group 3 teeth were kept in the dark and the other groups were exposed to daylight for 12 weeks.

Results

After 12 weeks, sunlight exposure had caused dark grey‐brown staining in the Ledermix groups but this did not occur when the teeth were kept in the dark. More severe staining was noted when Ledermix paste filled the pulp chamber than when the paste was restricted to below the CEJ and when teeth were exposed to sunlight. When compared to the results of a similar study using mature teeth, the results were similar but the immature teeth were more severely stained than the mature teeth. The Ca(OH)2 paste caused an increase in lightness and yellowness in immature teeth.

Conclusion

It was concluded that Ledermix paste may cause discolouration of immature teeth. Such effects can be minimized if placement of the paste is restricted to below the gingival margin. Clinicians should ensure that Ledermix paste is not left on the walls of access cavities, especially in immature teeth.
Lasers in endodontics: a review
Authors: Kimura Y. , Wilder‐Smith P. , Matsumoto K.
Published: March 2003

Since the development of the ruby laser by Maiman in 1960 and the application of the laser for endodontics by Weichman in 1971, a variety of papers on potential applications for lasers in endodontics have been published. The purpose of this paper is to summarize laser applications in endodontics, including their use in pulp diagnosis, dentinal hypersensitivity, pulp capping and pulpotomy, sterilization of root canals, root canal shaping and obturation and apicectomy. The effects of laser on root canal walls and periodontal tissues are also reviewed. The essential question is whether a laser can provide equal or improved treatment over conventional care. Secondary issues include treatment duration and cost/benefit ratio. This article reviews the role of lasers in endodontics since the early 1970s, summarizes many research reports from the last decade, and surmises what the future may hold for lasers in endodontics. With the potential availability of many new laser wavelengths and modes, much interest is developing in this promising field.
Radiographic evaluation of periapical healing after obturation of infected root canals: an in vivo study
Authors: Katebzadeh N. , Sigurdsson A. , Trope M.
Published: March 2003

Katebzadeh N, Sigurdsson A, Trope M. Radiographic evaluation of periapical healing after obturation of infected root canals: an in vivo study. International Endodontic Journal, 33, 60–65, 2000.

Aim  To radiographically compare periapical repair of roots with infected root canals obturated in one‐step or with calcium hydroxide (Ca(OH)2) intracanal medication in two steps.

Methodology Standardized preoperative periapical radiographs were taken of 72 roots of vital dogs' teeth. All roots were then aseptically instrumented to ISO size 45. As negative controls, 12 roots were aseptically obturated. The remaining roots were infected with dental plaque and closed. Six weeks later, apical periodontitis was radiographically confirmed in the infected roots. The roots were divided into the following groups: group 1, one‐step (n=24); roots were irrigated with 10 cc saline, obturated, and permanently restored. Group 2, Ca(OH)2 (n=24); roots were treated as in group 1, except that after saline irrigation Ca(OH)2 medicament was placed in the canal 1 week before obturation. Group 3, positive control (n=12); the

roots were irrigated with saline, access permanently closed but canals not obturated. Group 4, negative control (n=12); previously aseptically obturated roots were permanently restored. After 6 months, standardized postoperative radiographs were obtained. Three independent evaluators blinded to the treatment groups evaluated the preoperative and postoperative radiographs. The evaluators were instructed to rate each root, based on changes on the radiographs, as failed, improved or healed.

Results  Radiographically, the percentage of cases that completely healed were similar for the one‐step and Ca(OH)2 groups (35.3% vs. 36.8%). However, the Ca(OH)2 group had fewer failed cases (15.8% vs. 41.2%) and more improved cases (47.4% vs. 23.5%) than the one‐step group.

Conclusion  Power statistics demonstrated that at 43 cases per group, Ca(OH)2 treatment would be statistically superior to one‐step treatment. We consider this number to be clinically important.
Apparent periapical repair without operative intervention: a case report and discussion
Authors: Whitworth J. M.
Published: March 2003

Case report

A case is described where substantial reduction of an established periapical lesion appeared to take place in the absence of operative intervention, and as the crown of the tooth was progressively destroyed by dental caries. The case raises debate on the pathogenesis, diagnosis and monitoring of endodontic lesions, and may stimulate renewed research interest in these most fundamental elements of clinical endodontology.
A comparison of the relative efficacies of four hand and rotary instrumentation techniques during endodontic retreatment
Authors: Imura N. , Kato A. S. , Hata G.‐I. , Uemura M. , Toda T. , Weine F.
Published: March 2003

Aim

The purpose of this study was to quantify the amount of remaining gutta‐percha/sealer on the walls of root canals when two engine‐driven instruments (Quantec and ProFile) and two hand instruments (K‐file and Hedström file) were used to remove these materials. The amount of apically extruded debris and the time required for treatment were also recorded.

Methodology

One hundred extracted mandibular premolars were prepared using a modified step‐back, flare technique and obturated with the lateral condensation technique. After repreparation with the test instruments, the specimens were cut transversally at the cervical, middle and apical thirds with steel discs and the three sections were split longitudinally. The amount of residual debris on the canal walls in each section was examined using a stereomicroscope.

Results

In all groups the cervical and middle thirds showed no debris. In the apical third, obturating material was observed in some specimens. No statistically significant difference was found between the two groups for incidence of debris, although the Hedström group showed a greater number of samples with remaining gutta‐percha/sealer. When analysing dirty specimens only, there was a statistically significant difference between the four groups (P < 0.01) with the Hedström group having significantly less length of canal wall with remaining obturation material than the Quantec group. There was no significant difference amongst the groups for weight of extruded debris. However, there was a significant difference amongst the groups for mean treatment time with the Hedström file group requiring significantly less time than the Quantec group (P < 0.001); no significant differences were found between the other groups. Six instruments fractured in the Quantec group, four in the ProFile group, two in the Hedström group and two in the K‐type group.

Conclusions

The results showed that overall, all instruments may leave filling material inside the root canal. During retreatment there is a risk of instrument breakage, especially rotary instruments.
Lateral breakdown of nonendodontic origin adjacent to maxillary left incisors
Authors: Fristad I. , Hagen S. O. , Bårdsen A. , Molven O.
Published: March 2003

Case report

A 16‐year‐old female presented with a labial fistula located between the central and lateral left maxillary incisors. The teeth had normal colour, responded positively to pulp testing, demonstrated negative percussion tests and had no evidence of periodontal pockets. The patient reported no history of trauma, but mentioned that she had received orthodontic treatment. Radiographic examination showed bone loss between these two teeth. Explorative surgery followed by antibiotic treatment was performed, but a fistula reappeared after 22 months. Surgical retreatment combined with antibiotic treatment resulted in gradual healing over a three‐year period. No root canal treatment was performed. Aetiological considerations connected to tissue injury and inflammation are discussed. Inflammation induced disturbances in local homeostasis may possibly explain the lateral breakdown of bone. Such areas of reduced resistance may, under unfavourable conditions, be infected by blood‐born pathogens. Information about such aberrant cases is important in endodontic decision making.
Effect of exposing dentine to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus
Authors: Grigoratos D. , Knowles J. , Ng Y‐L. , Gulabivala K.
Published: March 2003

Aim

The aim of this study was to evaluate the effect of sodium hypochlorite (NaOCl) solutions (3%, 5%) and saturated calcium hydroxide (Ca(OH)2) solution, individually and consecutively, on the flexural strength and modulus of elasticity of standardized dentine bars.

Methodology

Standardized plano‐parallel dentine bars (n = 121) were divided into five test groups and one control group. The control group 1 consisted of dentine bars, stored in normal saline until testing. The dentine bars in the five test groups were treated by exposure to the following solutions; group 2 – 3% NaOCl, 2 h; group 3 – 5% NaOCl, 2 h; group 4 – saturated Ca(OH)2 solution, 1 week; group 5 – 3% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week; group 6 – 5% NaOCl, 2 h and then saturated Ca(OH)2 solution 1 week. The dentine bars were then loaded to failure in a three‐point bend test.

Results

The data revealed a significant (P < 0.001) decrease in the modulus of elasticity and flexural strength of the dentine bars treated with 3% and 5% NaOCl. There was no significant difference in the flexural strength and the modulus of elasticity between the 3% and 5% NaOCl groups. Exposure to Ca(OH)2 significantly (P < 0.001) reduced the flexural strength but had no significant effect on the modulus of elasticity. The groups treated with sodium hypochlorite followed by calcium hydroxide did not have moduli of elasticity and flexural strengths that were significantly different from those treated only with sodium hypochlorite.

Conclusions

NaOCl (3 & 5%) reduced the modulus of elasticity and flexural strength of dentine. Saturated Ca(OH)2 reduced the flexural strength of dentine but not the modulus of elasticity. Sequential use of NaOCl and Ca(OH)2 has no additional weakening effect.
Effect of access cavity location and design on degree and distribution of instrumented root canal surface in maxillary anterior teeth
Authors: Mannan G. , Smallwood E. R. , Gulabivala K.
Published: March 2003

Aim The null hypothesis tested in this study was that in single‐rooted anterior teeth with simple root canal anatomy, different access cavity designs (‘lingual cingulum’, ‘lingual conventional’, ‘incisal straight‐line’) do not influence the ability of endodontic files to plane the walls of the root canals.

Methodology  Thirty extracted human maxillary anterior teeth were divided randomly into three groups for each access cavity. The access cavities were prepared according to predefined criteria and the roots embedded in individual polyvinyl‐siloxane putty matrices. The matrices allowed these teeth to be split into buccal and palatal halves and to be reassembled. The split teeth enabled removal of pulpal remnants from the root canal system and the walls to be stained with an even layer of permanent black ink. Once dried, the split roots were reassembled in the putty matrices and a step‐back filing technique was used to prepare the canals with water irrigation. The canal walls were examined for residual ink staining and scored by three independent assessors using an index devised for the purpose.

Results There was good agreement between the assessors. None of the access cavities allowed file contact with the entire root canal wall. The overall (palatal and buccal sections) scores showed significant differences (P < 0.01) between the access cavity groups in the extent to which the canal walls could be filed. The straight‐line incisal access cavity had the greatest proportion of instrumented root canal surface. The lingual cingulum access cavity was the worst in this respect. The differences in residual ink scores between the access cavity types were significant for the buccal halves (P < 0.01) but not for the palatal halves (P > 0.05).

Conclusions The null hypothesis was proven. Regardless of access cavity design, mechanical preparation did not allow instrumentation of the entire root canal wall. Straight‐line access allowed the greatest proportion of the root canal wall to be instrumented and the lingual cingulum access the least.
The influence of two concentrations of sodium hypochlorite on human blood: changes in haemolysis, pH and protein
Authors: Yamaguchi H. , Hosoya N. , Kobayashi K. , Yokota T. , Arai T. , Nakamura J. , Cox C. F.
Published: March 2003

Aim To evaluate the in vitro effect of 2.5% and 5.0% sodium hypochlorite (NaOCl) on human blood.

Methodology Each concentration of NaOCl was reacted with human blood for 5 min at volume ratios of 1 : 1, 1 : 6, 1 : 12, each creating changes in colour, pH and temperature. Reaction suspensions were separated by centrifugation, and absorption measurements made for separated bilirubin, Fe, and protein supernatants. Each supernatant was desalted, lyophilized, and treated by SDS polyacrylamide gel electrophoresis (SOS‐PAGE).

Results Increased ratios and concentrations of NaOCl caused an increase in both pH and temperature. Protein supernatants tended to decompose on SDS‐PAGE. Supernatants showed increased decolourisation with 5.0% NaOCl. Concentrations of bilirubin, Ferrum and protein in supernatants decreased with increased NaOCl concentration. NaOCl had an effect on the protein component in blood.

Conclusions These data suggest that changes in molecular structure are due to the chemical effects of NaOCl. Protein bands tended to show low molecular weight, suggesting that haemoglobin components effect the oxidation‐reduction reaction.
Three phosphor plate systems and film compared for imaging root canals
Authors: Shearer A. C. , Mullane E. , Macfarlane T. V. , Gröndahl H.‐G. , Horner K.
Published: March 2003

Aim

The aim of this study was to compare three phosphor plate intraoral imaging systems (Digora (DA), Digident (DT), Denoptix (DX)) and E‐speed conventional film (CF) for the imaging of root canals.

Methodology

Sixty extracted permanent teeth were exposed using CF, DA, DT and DX. The length of root canal visible from its most apical extent to a line drawn at the level of the cementoenamel junction was measured and this was expressed as a percentage of the distance between the radiographic apex and the cementoenamel line. All images were examined concurrently by two examiners. Films were viewed under standardized conditions and DA, DT and DX images were viewed directly from the monitor screen. The images on the monitor were enhanced to give the subjectively clearest image.

Results

The mean percentage of canal visible on CF was 90%, DA 78%, DT 81% and DX 83%. The difference was significant for CF–DA (P < 0.001) and CF–DT (P = 0.001). There was no statistically significant difference for CF–DX or between any of the three phosphor plate imaging systems.

Conclusions

It is concluded that a greater length of root canal was visible on conventional film than on three phosphor plate imaging systems and that this may be of clinical significance.
Methodological considerations in the determination of working length
Authors: Martínez‐Lozano M. A. , Forner‐Navarro L. , Sánchez‐Cortés J. L. , Llena‐Puy C.
Published: March 2003

Aim

The aim of this study was to evaluate the diagnostic efficacy of an electronic system for the determination of working length, in comparison with two radiological methods (conventional film and digital radiography).

Methodology

The study sample consisted of 28 root canals belonging to 20 human mandibular teeth. A comparison was made between the working length measurements obtained by two radiological methods (conventional film and digital radiography) and an apex locator, using as gold standard the observation of the file position within the root following selective grinding of the root tissue.

Results

The electronic method was satisfactory in 67.8% of cases, versus 50.6% and 61.4% for the conventional and digital radiological methods, respectively. No statistically significant differences occurred between the techniques according to the chi‐squared and Kruskal–Wallis nonparametric tests.

Conclusions

None of the techniques was totally satisfactory in establishing the true working length. There were no differences between the techniques investigated.