bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative in vivo analysis of the sealing ability of three endodontic sealers in post‐prepared root canals
Authors: Kopper P. M. P. , Figueiredo J. A. P. , Della Bona A. , Vanni J. R. , Bier C. A. , Bopp S. 
Published: November 2003

AbstractAim  To compare the sealing ability of the endodontic sealers AH Plus, Sealer 26 and Endofill in premolar teeth of dogs exposed to the oral cavity after post‐preparation.Methodology  Forty teeth with two canals each underwent root canal cleaning and shaping. Before filling, the canals were randomly distributed into three groups according to the sealer to be used: Group 1 – AH Plus; Group 2 – Sealer 26; and Group 3 – Endofill (Dentsply, Indústria e Comércio Ltda.). Immediately after filling, the gutta percha and sealer were partially removed from the canals, leaving material only in the apical third of the root. The teeth were temporarily sealed with glass ionomer sealer for 72 h to ensure setting. The coronal seal was then removed and the canals were exposed to the oral cavity for 45 days. The animals were euthanased and their mandibles and maxillae were removed. After abundant irrigation with distilled water, the canals were dried and filled with India ink. The teeth were sealed again for 96 h before extraction. The roots of the extracted premolars were separated and stored in labelled test tubes. The roots were cleared and the extent of dye penetration was measured with a 20× stereoscopic magnifying lens.Results  Statistical analysis revealed that there were significant differences between the sealers studied (P < 0.001). Means for the extent of dye penetration for AH Plus, Endofill and Sealer 26 were, respectively, 0.13, 2.27 and 3.08 mm.Conclusions  After 45 days exposure to the oral cavity, none of the sealers was capable of preventing leakage and coronal dye penetration. There were significant differences between the sealers studied, in terms of mean dye penetration.
Incidence of rotary ProFile instrument fracture and the potential for bypassing in vivo
Authors: Al‐Fouzan K. S. 
Published: November 2003

AbstractAim  To determine the incidence of rotary ProFile instrument fracture and the potential for bypassing in molar teeth in vivo.Methodology  Four hundred and nineteen maxillary and mandibular first and second molars (1457 canals) were cleaned and shaped by two endodontists with new and used sets of nickel–titanium ProFile .04 taper rotary instruments. Each set of instruments was used in five molars and was steam‐autoclaved before use. The canals were instrumented using passive instrumentation and a crown‐down preparation technique. Instruments were examined both before and after use to evaluate whether breakage or deformation had occurred. All canals were instrumented to at least a size 30 at the working length.Results  Nineteen instruments demonstrated visible signs of plastic deformation and were discarded and replaced, whilst 21 instruments underwent intracanal fracture during treatment. Amongst these, 14 fractured in the apical third, whilst the remaining seven fractured in the middle third. Seven instruments were bypassed, and treatment was completed. There was a significantly greater number of instrument fractures with the size 20 ProFile than with the other sizes, especially after the second time of use (P < 0.05).Conclusions  Prolonged clinical use of ProFile nickel–titanium instruments increased their fracture rate. One‐third of fractured instruments were bypassed.
The relationship of intracanal medicaments to postoperative pain in endodontics
Authors: Ehrmann E. H. , Messer H. H. , Adams G. G. 
Published: November 2003

AbstractAim  To investigate the relationship of postoperative pain to three different medicaments placed in the root canal after a complete biomechanical debridement of the root canal system in patients presenting for emergency relief of pain.Methodology  Two hundred and twenty‐three teeth belonging to 221 patients presenting as emergencies to the Royal Dental Hospital of Melbourne were included in the study. Inclusion was limited to patients with a diagnosis of pulp necrosis and acute apical periodontitis. All teeth underwent conventional root canal treatment, which involved the instrumentation to the apices of each canal at the first visit. Canals were instrumented using a stepback technique and hand‐files along with irrigants using Milton's (1% sodium hypochlorite) solution followed by 15% EDTAC. The canals were dried and one of the following three medicaments was inserted into the canal in random sequence: Group 1: Ledermix paste (Lederle Pharmaceuticals, Division of Cyanamid, Wolfratshausen, Germany); Group 2: calcium hydroxide paste (Calcipulpe, Septodont, France); and Group 3: no dressing.Before dismissal, the preoperative pain experienced on the previous night was recorded using a visual analogue pain scale. Patients were then instructed to record the degree of pain experienced 4 h after treatment and daily for a further 4 days.Results  The mean score pain for all three groups was between 42 and 48 prior to treatment being commenced. After 4 days, the pain score for Group 2 was 10, for Group 3 was 7 and for Group 1 was 4. Mean preoperative pain level was 44.4 (of a maximum 100) for all groups, and declined by 50% (to 22.1) after 24 h. Patients in Group 1 (Ledermix) experienced significantly less (P = 0.04) postoperative pain than those in the other two groups. There was no significant difference between Group 2 (calcium hydroxide) and Group 3 (no dressing).Conclusion  Under the conditions of this study, painful teeth with acute apical periodontitis that had been dressed with Ledermix paste gave rise to less pain than that experienced by patients who had a dressing of calcium hydroxide or no dressing at all. Ledermix is an effective intracanal medicament for the control of postoperative pain associated with acute apical periodontitis, with a rapid onset of pain reduction.
Root canal preparation with FlexMaster: asessment of torque and force in relation to canal anatomy
Authors: Hübscher W. , Barbakow F. , Peters O. A. 
Published: November 2003

AbstractAim  To investigate physical parameters of FlexMaster nickel‐titanium instruments while preparing curved canals in maxillary molars in vitro.Methodology  A torque‐testing platform was used to prepare root canals in 11 extracted human maxillary molars with FlexMaster rotary instruments. Peak torque and force was registered along with numbers of rotations required to shape the canals. Canals were divided into ‘wide’ and ‘constricted’ groups depending on canal volumes assessed by microcomputed tomography. Resistance to cyclic fatigue was also tested. Mean scores for each instrument type were calculated and statistically compared using anova and Scheffé post hoc tests.Results  Mean torque varied between 0.1 ± 0.1 and 0.8 ± 0.5 N cm while mean force ranged from 4.2 ± 2.0 to 7.3 ± 3.5 N. Mean numbers of rotations totalled up to 18. All three variables registered showed weak correlations to preoperative canal volumes (P < 0.01) and differed significantly between ‘wide’ and ‘constricted’ canals (P < 0.001). Numbers of rotations to fracture in a cyclic fatigue test were between 348 and 1362.Conclusion  FlexMaster instruments generated low torque scores and were highly resistant to cyclic fatigue, whilst three instruments fractured in extremely narrow canals. Consequently, more research is required to limit fracture incidence and to optimize instrumentation guidelines.
Diagnosis and root canal treatment of a mandibular second premolar with three root canals
Authors: Rödig T. , Hülsmann M. 
Published: November 2003

AbstractAim  To present a case of a mandibular second premolar with three root canals.Summary  An accurate diagnosis of the morphology of the root canal system is a prerequisite for successful root canal treatment. A review of the literature reveals a low incidence of all types of premolars with three root canals. Diagnostic means such as preoperative radiographs and examination of the pulp chamber floor aid the location of root canal orifices. The diagnostic and therapeutic problems concerning premolars with unusual anatomy are described on the basis of a clinical example. A case report describes the successful treatment of a mandibular second premolar with three root canals.Key learning points

Clinicians should be aware of unusual root canal anatomy in mandibular premolars.
Radiographs exposed at two different horizontal angles and their careful interpretation facilitate the search of additional root canals.
The use of magnification and additional lighting are recommended for the clinical examination of the pulpal floor.
Comparison of neurotoxicity of root canal sealers on spontaneous bioelectrical activity in identified Helix neurones using an intracellular recording technique
Authors: Asgari S. , Janahmadi M. , Khalilkhani H. 
Published: November 2003

AbstractAim  To evaluate the neurotoxic effects of two endodontic sealers, AH‐26 and Roth 801, on firing excitability and action potential configuration of F1 neural cells in the suboesophageal ganglia of Helix aspersa.Methodology  A conventional intracellular current clamp technique was used to study the blocking effects of AH‐26 and Roth 801 on ionic currents underlying the action potential of F1 nerve cells. The sealers were prepared according to the manufacturers' directions and were applied to the bathing media in two ways: invasive (0.05 mL of total mixture of each sealer was applied at a distance of 3 mm from the cell), or gradual (0.05 mL of the extract of each dissolved mixture of sealers in normal Ringers solution was perfused).Results  When applied in an invasive mode, both sealers reduced the duration, the amplitude of action potentials and the amplitude of after‐hyperpolarization potentials significantly and led to dramatic changes in action potential configuration. In the gradual mode of application, AH‐26 showed a biphasic action; it first increased the excitability and then decreased the action potential parameters, while Roth 801 exhibited solely blocking effects.Conclusions  Both sealers had significant inhibitory effects on excitability of F1 neuronal cells.
Chelating agents in root canal treatment: mode of action and indications for their use
Authors: Hülsmann M. , Heckendorff M. , Lennon Á. 
Published: November 2003

AbstractChelating agents were introduced into endodontics as an aid for the preparation of narrow and calcified root canals in 1957 by Nygaard‐Østby. A liquid solution of ethylenediaminetetraacetic acid (EDTA) was thought to chemically soften the root canal dentine and dissolve the smear layer, as well as to increase dentine permeability. Although the efficacy of EDTA preparations in softening root dentine has been debated, chelator preparations have regained popularity recently. Almost all manufacturers of nickel–titanium instruments recommend their use as a lubricant during rotary root canal preparation. Additionally, a final irrigation of the root canal with 15–17% EDTA solutions to dissolve the smear layer is recommended in many textbooks. This paper reviews the relevant literature on chelating agents, presents an overview of the chemical and pharmacological properties of EDTA preparations and makes recommendations for their clinical use.
Phagocytosis ofCandida albicansand Superoxide Anion Levels in Ring Dove (Streptopelia risoria) Heterophils: Effect of Melatonin
Authors: Terrón M. P. , Cubero J. , Barriga C. , Ortega E. , Rodríguez. A. B. 
Published: November 2003

AbstractWe observed in previous studies on avian heterophils that incubation with either physiological or pharmacological concentrations of the neurohormone melatonin increased the phagocytosis of inert particles (latex beads), and also provoked a decline in superoxide anion levels of those phagocytes. In the present study, we wanted to corroborate whether melatonin acts on the oxidative metabolism that accompanies the respiratory burst during phagocytosis by inducing a more effective phagocytic activity at the same time as exerting an antioxidant effect to eliminate and/or scavenge the free radicals left over after the destruction of the foreign material. To this end, we evaluated the ingestion and destruction ofCandida albicans(live particles) by ring dove (Streptopelia risoria) heterophils after different times of incubation (30 and 60 min) with physiological concentrations of melatonin (50 pg/ml diurnal and 300 pg/ml nocturnal), as well as with a pharmacological concentration 23 × 106 pg/ml (100 µm) of the hormone. In parallel, using the same times of incubation, we evaluated the oxidative metabolism by determining the superoxide anion levels (O2−·). The results show that melatonin, at all the times and concentrations studied, increases both the phagocytosis index (number ofC. albicansphagocytosed by 100 heterophils) and the candidicide power (percentage ofC. albicanskilled of those ingested by 100 heterophils). The effect was dose‐dependent. With respect to the oxidative metabolism accompanying the digestion and destruction, there was a decline in superoxide anion levels after incubation with all of the concentrations of the hormone studied. The effect was dose‐dependent and most pronounced at 60 min. These results thus corroborate the proposal that melatonin enhances the phagocytic function at the same time as neutralizing the oxidative stress derived from this immune function.
Monoaminergic Activity in Subregions of Raphé Nuclei Elicited by Prior Stress and the Neuropeptide Corticotropin‐Releasing Factor
Authors: Summers C. H. , Kampshoff J. L. , Ronan P. J. , Lowry C. A. , Prestbo A. A. , Korzan W. J. , Renner K. J. 
Published: November 2003

AbstractCorticotropin‐releasing factor (CRF) coordinates neuroendocrine responses to stressful stimuli; one mechanism through which CRF may modulate hypothalamic‐pituitary‐adrenal axis activity is via actions on neuromodulatory systems such as serotonergic systems. Recent electrophysiological studies and the distribution of CRF receptors within midbrain and pontine raphé nuclei suggest that stress and CRF may have actions on topographically organized subpopulations of serotonergic neurones. We compared the effects of vehicle or intracerebroventricular r/hCRF injections (0, 0.1, 1 or 10 µg) in rats previously maintained in home cages or restrained for 1 h, 24 h before injection, on monoamine and monoamine metabolite tissue concentrations in the dorsal (lateral wings, rostral midline, caudal midline), median (rostral, caudal) and interfascicular raphé subdivisions of the midbrain and pontine raphé nuclei, using brain microdissection and high‐performance liquid chromatography with electrochemical detection. At the lowest dose studied (0.1 µg), CRF infusions in previously stressed rats decreased 5‐hydroxytryptophan (5‐HTP) and 5‐hydroxyindoleacetic acid (5‐HIAA) concentrations only within the rostral median raphé nucleus. At higher doses, CRF infusions in previously stressed rats increased tissue concentrations of 5‐HTP, serotonin (5‐HT), or the serotonin metabolite, 5‐HIAA, within rostral (but not caudal) regions of the median and dorsal raphé nuclei. By contrast, restraint stress alone had no effect on tissue concentrations of 5‐HTP, 5‐HT or 5‐HIAA measured 24 h later in any subdivision, while CRF injections in rats not previously exposed to restraint stress, with few exceptions, also had no effect. These results suggest that the effects of CRF on serotonergic function are context‐dependent, dose‐dependent, and regionally specific within subdivisions of the brainstem raphé nuclei.
Evidence From Studies on Co‐Cultures of TtT/GF and AtT20 Cells That Annexin 1 Acts as a Paracrine or Juxtacrine Mediator of the Early Inhibitory Effects of Glucocorticoids on ACTH Release
Authors: Tierney T. , . Christian H. C , . Morris J. F , Solito E. , . Buckingham J. C 
Published: November 2003

AbstractAnnexin 1 (ANXA1) is a key mediator of the inhibitory effects of glucocorticoids on adrenocorticotropic hormone (ACTH) release, which develop within 1–2 h of a steroid challenge. Our previous studies, which showed that (i) ANXA1 is expressed principally by the nonsecretory folliculo‐stellate cells in the pituitary gland; (ii) glucocorticoids cause the exportation of ANXA1 from these cells; and (iii) corticotrophs express specific ANXA1 binding sites, led us to propose that ANXA1 serves as a paracrine or juxtacrine mediator of glucocorticoids. To address this hypothesis, we examined ANXA1‐dependent glucocorticoid actions in co‐cultures of murine corticotroph (AtT20 clone D1) and folliculo‐stellate (TtT/GF) cell lines. ANXA1 mRNA and protein were found in abundance in TtT/GF cells but neither was detectable in the AtT20 cells. AtT20 cells (alone and in co‐culture with TtT/GF cells) responded to corticotropin‐releasing hormone (CRH) (0.1–1 µm) with increased ACTH release. The CRH‐stimulated release of ACTH from AtT20 cells cultured alone was unaffected by preincubation with dexamethasone (Dex, 100 nm); by contrast, in co‐cultures of AtT20 and TtT/GF cells, the steroid readily inhibited the secretory response to CRH. The effects of Dex on ACTH release were mimicked by N‐terminal ANXA1 fragments (ANXA1Ac2−26, 2 µg/ml and ANXA11‐188, 0.1 ng/ml) and reversed by mifepristone (1 µm) and by an antisense oligodeoxynucleotide (ODN) to ANXA1 (50 nm) but not by control ODNs. The antisense ODN also specifically blocked the Dex‐induced externalization of ANXA1 from TtT/GF cells. Immunofluorescence imaging of the co‐cultures localized the exported protein to the vicinity of the AtT20 cells and identified ANXA1 binding sites on these cells. These results provide functional and histological evidence to support our premise that the early inhibitory effects of glucocorticoids on ACTH release are dependent upon paracrine/juxtacrine actions of ANXA1 derived from folliculo‐stellate cells.
The Diurnal Modulation of Hormonal Responses in the Rat Varies with Different Stimuli
Authors: Kalsbeek A. , Ruiter M. , La Fleur S. E. , Van Heijningen C. , Buijs R. M. 
Published: November 2003

AbstractThe circadian clock, located in the suprachiasmatic nuclei (SCN) of the hypothalamus not only controls the basal daily temporal organization of many neuroendocrine functions, but also its responsiveness. We studied the time‐of‐day influence on plasma changes in adrenocorticotropic hormone (ACTH), corticosterone, glucagon and leptin concentrations elicited by an insulin‐induced hypoglycaemic event. Male Wistar rats were exposed to an insulin challenge at six different times during the light/dark cycle. The time‐of‐day of exposure markedly affected the responses of all four hormones studied. Generally, the magnitude of the different hormone responses correlated with their basal daily release pattern (i.e. the responses of ACTH and corticosterone were largest around lights off, and glucagon and leptin responses were most pronounced during the dark period). With regard to the hormones of the hypothalamic‐pituitary‐adrenal axis, the presently reported time‐of‐day dependent modulation is completely opposite to that previously reported for novelty or restraint. Therefore, these findings provide further support for the existence of at least two different neural pathways that are able to activate the hypothalamic‐pituitary‐adrenal axis, and provide different substrates for modulation by the biological clock. This observation warrants a thorough examination of possible functional explanations for the observed differences.
Effects of Agouti‐Related Protein on Metabolism and Hypothalamic Neuropeptide Gene Expression
Authors: Korner J. , Wissig S. , Kim A. , Conwell I. M. , Wardlaw S. L. 
Published: November 2003

AbstractThe hypothalamic melanocortin system regulates feeding in part through interaction of the appetite stimulating peptide, agouti‐related protein (AGRP), and the anorectic peptide, α‐melanocyte stimulating hormone, a peptide derived from the pro‐opiomelanocortin (POMC) polyprotein. Central administration of AGRP induces hyperphagia and increased gain in body weight in rodents, but may also exert metabolic effects even when hyperphagia is prevented. In the present studies, the effects of AGRP on hypothalamic neuropeptide gene expression and metabolism were examined in the rat. Central administration of AGRP for 3‐ and 7‐day periods resulted in hyperphagia, increased body weight and increased plasma leptin and insulin concentrations compared to saline‐injected controls. Hypothalamic concentrations of Pomc mRNA were also increased by 27% and 44% (in 3‐ and 7‐day experiments, respectively). The hypothalamic concentration of Agrp mRNA was unchanged after 3 days, but was significantly decreased by 33% after 7 days of AGRP infusion. To determine if these changes were dependent upon AGRP‐induced hyperphagia, pair‐fed rats with restricted food intake receiving central administration of AGRP were also studied. In the absence of hyperphagia, intracerebralventricular administration of AGRP caused significant increases in plasma leptin and insulin concentrations (two‐fold and 1.5‐fold, respectively) and fat pad mass. A significant increase in hypothalamic Pomc mRNA concentrations was not detected in pair‐fed rats. In contrast, Agrp mRNA concentrations remained suppressed by 45% in the pair‐fed group after 7 days of AGRP infusion despite equal body weight compared to saline controls. The ratio of hypothalamic Pomc to Agrp mRNA was elevated two‐fold in ad libitum and pair‐fed AGRP‐injected rats, which is consistent with increased stimulation of central melanocortin signalling pathways. Thus, central administration of AGRP exerts changes in hypothalamic neuropeptide gene expression and metabolic effects that are independent of the effects on food intake and body weight.
The Hormone Domain of the Vasopressin Prohormone is Required for the Correct Prohormone Trafficking Through the Secretory Pathway
Authors: De Bree F. M. , Van Der Kleij A. A. M. , Nijenhuis M. , Zalm R. , Murphy D. , Burbach J. P. H. 
Published: November 2003

AbstractIt has long been known that under intracellular conditions vasopressin associates tightly to neurophysin, which is present in the same prohormone. As the association has been suggested to play a role during hormone biosynthesis, its role was studied in a cellular context by expressing mutant vasopressin precursors in Neuro2A cells. Mutant vasopressin precursors, in which the association between the vasopressin and neurophysin domains was prevented either by deleting the vasopressin domain from the precursor or by substitution of the essential Tyr2 residue in vasopressin for Gly, were neither processed nor targeted into secretory granules. Rather, both provasopressin mutants were retained in the endoplasmic reticulum. Our results demonstrate that the vasopressin domain is crucial for correct trafficking of the prohormone through the secretory pathway, and suggest that vasopressin–neurophysin association provides correct prohormone folding in the endoplasmic reticulum.