bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variability Of Master Gutta‐Percha Cones
Authors: Moule Alex J. , Kellaway Richard , Glarkson Roger , Rowell John , Macfarlane Richard , Lewis Derek , Cameron Tony , Atkins Darryl 
Published: February 2010

AbstractThe common technique to hermetically fill prepared root canals involves the use of “standardised” guttapercha cones that are selected to fit the apical portion of the prepared canal space. These guttapercha cones are manufactured to conform to a standard size and taper which should correspond to the size and taper of standard root canal instruments. Clinical observation of commercially available guttapercha cones seemed to indicate that there is wide variation in the diameter and taper of “standardised” gutta‐percha cones within the size range 25–35. The present study was undertaken to determine how closely current commercially available gutta‐percha cones sizes 25, 30 and 35 conformed to the current ISO standard, and was initiated by the above clinical observation. It was not the purpose of this study to compare the results from different brands or manufacturers, but rather to establish whether commercially available gutta‐percha cones collectively conformed to expected standardised sizes.One phial of cones for each of the sizes 25, 30 and 35 of eight different brands was selected for examination. The diameter of each of ten cones for each size from each brand was measured at two points, at 1 mm and at 6 mm from the tip of the cone. The results obtained for each size and each brand were tabulated and compared with ISO 6877:1995 for dental root canal obturating cones.This study demonstrated wide variability for cones from all brands, for all sizes, when individual cones of the same size were compared. While collectively the arithmetic means showed a closer correlation to the ISO Standard, irrespective of the brand size of the cone, or whether the cone was measured at 1 mm or 6 mm, many individual cones showed a great variation from the ideal. The need for less variability is discussed. It is concluded that ISO standard 6877:1995 is inappropriate and allows for too much variation in the size of “standardised” gutta‐percha cones.
Staphylococcus epidermidis And Staphylococcus xylosus In A Secondary Root Canal Infection With Persistent Symptoms: A Case Report
Authors: Siqueira J.F. , Lima K.C. 
Published: February 2010

AbstractThe aim of this case report is to highlight the importance of maintaining the aseptic chain during endodontic treatment. This paper describes a clinical situation in which persistent symptoms had developed after the first appointment to treat a vital pulp case. Microbiological analysis of the case indicated that symptoms were probably due to a secondary root canal infection by two species of coagulase‐negative staphylococci — Staphylococcus epidermidis and Staphylococcus xylosus. Symptoms had persisted in spite of using various intracanal antimicrobial agents and systemic antibiotic therapy.
The Diagnosis Of Referred Orofacial Dental Pain
Authors: Ehrmann E. H. 
Published: February 2010

AbstractEvery patient's description of the location of pain must be treated with caution. In order to arrive at a diagnosis of pain a logical method should be employed. This consists of the history and clinical examination including pulp tests and radiographs. Where the patient complains of pain on hot or cold, an attempt should be made to reproduce the patient's pain to check on the accuracy of its description and to aid in localisation.Patients frequently refer pain to previously endodontically‐treated teeth. These may not be the cause of the problem. In order to facilitate the process of diagnosis the following hypothesis has been advanced.A tooth can only be the source of pain if there are objective signs associated with that tooth. Lack of response to pulp tests constitutes such a sign, provided the tooth has not previously been endodontically treated. If, however, such treatment has taken place, (regardless of whether this was well or poorly executed), a further objective sign other than lack of vitality is required before such a tooth can be implicated as the source of pain. The guidelines suggested are illustrated by means of clinical examples.
The Periapical Space — A Dynamic Interface*
Authors: Abbott Paul V. 
Published: February 2010

AbstractThe ultimate aim of endodontic treatment is to encourage the healing of apical periodontitis, or to prevent it from occurring if it was not present prior to treatment. Apical periodontitis is a general term used to describe an inflammatory response to irritation caused by the contents of a root canal system and it has several distinct forms. The most common is a granuloma but this can develop into other disease entities such as an abscess, a periapical pocket cyst or a true cyst, all of which present as radiolucencies. However, periapical radiolucencies may also be caused by extra‐radicular infections, foreign body reactions and periapical scars, or they may be due to other tumours and cysts that have not originated from pulp disease. Practitioners must recognise and understand the different pathological entities and the dynamic interactions that occur in the periapical tissues in order to correctly diagnose and treat these conditions.
To Do A “Root Canal”
Authors: Spångberg Larz S.W. 
Published: February 2010

ABSTRACTEndodontic treatment is often referred to as “a root canal”. This article discusses the need to be more refined and descriptive in the selection of treatment alternatives. The pathological involvement of teeth needing endodontic treatment varies significantly from superficial pulp inflammation to pulp necrosis and infection, often complicated with a periradicular osteolytic process. This diversity should lead to a variety of treatment modalities based on the severity of the disease. Failure to do so and use a one‐size‐fits‐all approach – “a root canal” – is an oversimplification and a disservice to the patient and the profession.
Cytotoxicity Of A New Endodontic Filling Material
Authors: Gambarini Gianluca , Andreasi‐Bassi M. , Bolognini G. , Testarelli L. , Nocca G. , Ceccarelli L. , Scatena R. , Lupi A. , Castagnola M. 
Published: February 2010

ABSTRACTIn vitro cell cultures have been widely used as a means of evaluating cytotoxicity of root canal filling materials. Following ANSI/ADA spec. no. 41, the aim of the present study was to investigate the biological compatibility of a new sealer (FibreFill) and compare it with some commercially available endodontic sealers (Bioseal and Acroseal). Mouse 3T3 fibroblasts were seeded and cultured and subsequently extracts of the cements were added. After 24 hours incubation, the cellular vitality of fibroblasts was evaluated by the neutral red uptake test (NRU), which measures the membrane permeability. Data were collected and statistically analysed. Results showed that all tested materials exhibited mild cytotoxic effects, which are compatible with normal clinical use, and no statistically significant difference was noted between FibreFill and the other tested materials. Therefore, selection amongst these sealers should be based on other factors.
Adhesion Of A Glass‐Ionomer Root Canal Sealer To Human Dentine
Authors: Najar A.L. , Saquy P.C. , Vansan L.P. , Sousa‐Neto Manoel D. 
Published: February 2010

ABSTRACTThis in vitro study evaluated the effect of smear layer removal on adhesion to human dentine of Ketac‐Endo, Grossman, and Sealer 26 root canal sealers. A total of 60 extracted human maxillary and mandibular molars with their crowns ground flat were used. The teeth were divided into two groups: Group I, the dentine surface received no treatment; Group 2, EDTA‐C was applied to the dentine surface for 5 min. Ten samples were tested for each sealer and each group. Adhesion was measured with a Universal Testing Machine. Sealer 26 showed greater adhesion both with and without smear layer (p < 0.01). Ketac‐Endo and Grossman sealers were statistically equal, having the lowest values of adhesion. Application of EDTA‐C did not alter the adhesion of Ketac‐Endo and Grossman sealers. However, the use of EDTA‐C increased the adhesion of Sealer 26. The epoxy resin‐based root canal sealer (Sealer 26) adhered better to dentine prepared with and without EDTA‐C than glass‐ionomer‐based sealers and the zinc oxide eugenol‐based (Ketac‐Endo and Grossman) sealers.
The Use Of An Ultrasonic Technique To Remove A Fractured Rotary Nickel‐Titanium Instrument From The Apical Third Of A Curved Root Canal
Authors: Ward Jeff R. 
Published: February 2010

ABSTRACTThe frequency of use of nickel‐titanium rotary instruments in endodontic practice is increasing. One occasionally mentioned problem is fracture of an instrument within the root canal. The broken instrument may prevent access to the root apex, impeding optimal cleaning and shaping procedures. A case report is presented which uses a modern technique, utilising a staging platform and the use of newly designed ultrasonic tips with direct visualisation through a dental operating microscope, to remove a fractured rotary nickel‐titanium instrument from the apical third of a curved root canal.
A Comparative Analysis Of Mineral Trioxide Aggregate And Portland Cement
Authors: Funteas Urania R. , Wallace J.A. , Fochtman F.W. 
Published: February 2010

ABSTRACTThe purpose of this study was to compare the composition of Portland cement and Mineral Trioxide Aggregate (MTA). Samples of MTA and Portland cement were analysed for fifteen different elements by inductively coupled plasma emission spectrometry (ICP‐ES). Comparative analysis revealed there was significant similarity except there was no detectable quantity of Bismuth in Portland cement. Quantitative results are given in both parts per million (p.p.m.) and wt%. It was concluded that there is no significant difference between the 14 different elements in both Portland cement and MTA.
Inaugural Geoffrey Heithersay Oration In Endodontics And Oral Biology
Authors: Heithersay Geoffrey S. 
Published: February 2010

AbstractSmiles are often a reflection of dental health, and as such provide great satisfaction to a dental practitioner who has successfully managed complex dental problems such as malformed, malpositioned or traumatically damaged teeth. A biological approach to the management of the pulpal and periodontal responses to dental trauma has been made possible by cumulative research, and application of this knowledge will enhance successful treatment.
Nickel‐Titanium Rotary Instruments: Current Concepts For Preparing The Root Canal System*
Authors: Ruddle Clifford J. 
Published: February 2010

AbstractThe purpose of this paper is to provide useful information that will enable dentists to predictably shape root canals for three‐dimensional obturation of the root canal system. The information is intended to help clinicians better understand when and how to safely use Nickel‐Titanium (NiTi) rotary shaping instruments. This article is intended to enhance clinical performance for all dentists who perform root canal preparation procedures regardless of which instruments are chosen and the techniques employed during their utilisation. The guidelines for successful access and the concepts and strategies for canal preparation are discussed. Additionally, the advantages of negotiating and then pre‐enlarging the coronal two‐thirds of the canal before negotiating and finishing the apical one‐third are emphasised. Although a set of endodontic instruments can shape a root canal, this article will also review the importance of irrigants and their role in cleaning the root canal system.
An Experimental Study On The Vasoconstriction Effect Of Calcium Hydroxide Using Rat Mesentery
Authors: Kikuchi Izumi , Wadachi Reiko , Yoshioka Takatomo , Okiji Takashi , Kobayashi Chihiro , Suda Hideaki 
Published: February 2010

AbstractCalcium hyroxide has been used for eliminating persistent intracanal exudation. In order to address the mechanism behind this action, we investigated whether calcium hydroxide solutions cause the constriction of microvessels in the mesenteric microcirculation bed of rats. The exteriorised mesentery from anaesthetised rats was spread in a chamber, and arterioles, venules and capillaries were viewed under a digital microscope. Various concentrations of calcium hydroxide solutions were applied for 10 sec, and the diameter of the microvessels was recorded. In arterioles, calcium hydroxide solutions caused rapid and transient constriction. A statistically significant difference versus original diameter was detected I min after the application of 4.0 times 10−3 mol/l and 1.0 times 10−2 mol/l solutions (p < 0.05, one‐way analysis of variance and Tukey‐Kramer test). No statistically significant constriction occurred in capillaries and venules. It was concluded that the arteriolar constriction might be an explanation for the exudation‐controlling effect of intracanal calcium hyroxide dressings.
Contemporary Perspectives On Post‐Core Systems
Authors: Berekally Tom 
Published: February 2010

AbstractThe challenge of restoring endodontically‐treated teeth has spawned a considerable diversity in foundation restorations and a plethora of publications in the dental literature. Moreover, it seems that an inverse relationship has developed between the escalating complexity in selecting a post‐core system and the volume of reliable scientific data upon which clinicians base their treatment decisions. In the quest to restore aesthetics, function, and reduce the risk of treatment failure there is now a much greater emphasis on the preservation of sound tooth structure, tooth isolation for intracanal procedures, sealing the root canal and adapting the advantages and limitations of dental materials to the presenting clinical situation. The relatively recent introduction of metal‐free posts into mainstream prosthodontics has added an aesthetic dimension to treatment planning. New adhesive systems and resin‐based luting agents have the potential to create a genuine adhesive continuum between the tooth and post‐core complex. While these developments may have significant ramifications with respect to treatment prognosis, the long‐term clinical performance of contemporary post‐core systems is unclear.
Recent Advances In Therapeutic Exercise For The Neck: Implications For Patients With Head And Neck Pain
Authors: BPhty S. O'Leary , BPhty D. Falla , MPhty G. Jull 
Published: February 2010

AbstractThere have been recent advances in the rehabilitation of the muscles that control the head and neck. These advances are based on evidence of specific neck muscle dysfunction in individuals with persistent head and neck pain. Traditional rehabilitation strategies have focused predominantly on muscle strength and endurance under high loads. New evidence suggests that in people with neck pain there are underlying neuromuscular problems that may require more immediate attention and may not be adequately addressed by simple strength and high‐load endurance retraining. Evidence of altered coordination between the deep and superficial neck muscles, greater neck muscle fatigue under sustained low loads, and deficits in kinaesthetic sense have been identified in symptomatic individuals. There is evidence to indicate that addressing these muscle control problems, with specific gentle exercise strategies, results in a reduction in neck pain and associated symptoms.
Unusual Maxillary Lateral Incisors: Case Reports
Authors: Low Danny , Chan Alex W.K. 
Published: February 2010

AbstractRoot canal morphology is often complex and the number of root canals may vary for any type of tooth. Abnormalities in the root canal morphology of maxillary lateral inciors are rare. Maxillary lateral incisors can have two root canals, even though the dental literature supports their 100% single‐canal anatomy. It is vital to consider the possibility of extra root canal(s), even in teeth with a low frequency of abnormal root canal anatomy. This report presents two cases of maxillary lateral incisors with two root canals.
Photo‐Activated Disinfection Of The Root Canal: A New Role For Lasers In Endodontics
Authors: Lee Michael T. , Bird Philip S. , Walsh Laurence J. 
Published: February 2010

Because micro‐organisms play a crucial role in the development of pulpal and periapical disease, the prognosis of endodontic therapy is intimately related to the presence of bacteria within the root canal system. Micro‐organisms may persist in the apical region of the root canal system despite chemomechanical preparation. The usefulness of Class IV lasers (such as Nd:YAG, diode, KTP and Er:YAG) for photo‐thermal disinfection of the root canal has been demonstrated in numerous studies.An alternative approach to microbial killing in the root canal system by laser light involves the use of low‐power lasers to drive a photochemical reaction that produces reactive oxygen species, a technique termed photo‐activated disinfection (PAD). By using exogenous photosensitisers such as tolonium chloride, killing of all types of bacteria can be achieved. In vitro studies of PAD have demonstrated its ability to kill photosensitised oral bacteria (such as E. faecalis), and more recently microbial killing in vivo in the root canal system has been demonstrated. While PAD can be undertaken as part of the routine disinfection of the root canal system, it also has potential use for eradicating persistent endodontic infections for which conventional methods have been unsuccessful.
Apically‐Extruded Debris Using The ProTaper System
Authors: Azar Nasim Gheshlaghi , Ebrahimi Gholamreza 
Published: February 2010

The purpose of this in vitro study was to determine the quantity of debris and irrigant extruded apically using the ProTaper system compared to ProFiles and K‐Flexofiles.Thirty‐six mesio‐buccal root canals of human mandibular molars were selected and divided into three groups of twelve canals. Two groups were instrumented with ProFiles and ProTapers according to the manufacturer's instructions. The other group was instrumented with K‐Flexofiles using the step‐back technique. A standard amount of irrigant was used for each canal. Apically‐extruded debris and irrigant was collected in pre‐weighed vials. The mean weight of extruded debris and irrigant for each group was statistically analysed using Student's t‐test and one‐way ANOVA.All instrumentation techniques produced extruded debris and irrigant. Although the mean amount of extrusion with the step‐back technique was higher than the two rotary systems, there was no significant difference between the three groups (p > 0.05).NiTi rotary systems were associated with less apical extrusion, but were not significantly better than hand file instrumentation. All techniques extruded debris.
What We Leave Behind In Root Canals After Endodontic Treatment: Some Issues and Concerns
Authors: Sum Chee Peng , Neo Jennifer , Kishen Anil 
Published: February 2010

AbstractThe benefits of using sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) as endodontic irrigants, and calcium hydroxide as an inter‐appointment medicament, are well known to dentists. Many steps undertaken during endodontic treatment and retreatment are rather mechanical in nature, and less attention is committed to understanding the biological issues underlying endodontic treatment and retreatment. It should be noted that dentine is the fundamental substrate in endodontic treatment, and its properties and characteristics are the key determinant of nearly all disease and post‐disease processes in the teeth. In this article the effects and counter‐effects of NaOCl and EDTA on root canal dentine, and some other related issues are reviewed. This information will enable clinicians to use the beneficial effects of these chemicals, while necessary steps are considered to reduce their harmful effects on dentine substrate.
The Envelope Damage of Tetrahymena in the Presence of TiO2 Combined with UV Light
Authors: Peng Liu , Wenli Duan , Qisui Wang , Xi Li 
Published: February 2010

AbstractThe biological consequences of exposure to TiO2, UV light and their combined effects were studied on the cellular envelopes of Tetrahymena. For Tetrahymena cells treated with TiO2 or UV light alone, the cell membrane shrunk while still maintaining the original elliptoid shape. Cells treated by TiO2 under UV light irradiation experienced the most serious damage by peroxidation. A pear‐shaped cell was formed due to serious shrinkage and cilia loss. An increase in the fluorescence polarization of 1,6‐diphenyl‐1,3,5‐hexatriene was observed, indicating a significant decrease in membrane fluidity. Quantum dot (QD) labeling revealed that damaged cells could not function properly or absorb extracellular materials selectively. QDs were able to enter the damaged cells or be absorbed on the cell surface. Attenuated total reflection Fourier transform infrared spectra revealed that amide groups and PO2− of the phospholipid phospho‐diester, both in the hydrophobic end exposed to the outer layer, were the easiest to be oxidized. Other groups like CH2 and CH3 were also involved, but showed a resistance to photocatalytic peroxidation. The differences can be attributed to the bond energy as well as the ordering and position of the groups.
Optical Properties of Fluorescein‐labeled Organoclay
Authors: Lee Young‐Chul , Lee Tae‐Ho , Han Hyo‐Kyung , Go Woon Jung , Yang Ji‐Won , Shin Hyun‐Jae 
Published: February 2010

AbstractWe report the preparation of aminopropyl‐functionalized magnesium phyllosilicate (Mg‐organoclay) conjugated to fluorescein isothiocyanate (FITC) functionality (FITC‐organoclay) by one‐pot sol‐gel synthesis. The physical characteristics of the Mg‐ and FITC‐organoclays were examined by scanning electron microscopy (SEM), X‐ray diffraction (XRD), FT‐IR and UV–Vis spectrophotometry. X‐ray fluorescence and elemental analysis were conducted to confirm the composition of the Mg‐organoclay. The FITC‐organoclay particles were polydispersed with an average particle size of ∼50 nm, as determined from SEM images. The XRD patterns of FITC‐organoclay exhibited broad peaks and reduced basal d001 indicating a less condensed and more disordered structure than was observed for Mg‐organoclay. The conjugation between FITC‐ and Mg‐organoclay was characterized by FT‐IR spectroscopy. Fluorescence excitation and emission spectral data demonstrated the successful conjugation of FITC dye molecules to the Mg‐organoclay. The time‐resolved fluorescence measurements revealed that FITC had a lifetime of 4.58 ns, whereas the lifetime of FITC‐organoclay required a double exponential fit (τ1,2 = 0.72 and 2.68 ns). As a result, the lifetime of the FITC‐organoclay was shorter than that of FITC in ethanol and indicated moderate photostability in the solution state. The cellular uptake of FITC‐organoclay in human lung alveolar carcinoma epithelial cells (A549) was quantified and characterized.
Credit Spreads with Jump Risks and Stationary Leverage Ratio*
Authors: Kim Hwa‐Sung 
Published: February 2010

AbstractRecent structural models have utilized new factors to enhance their exploratory power over credit spreads. Some studies have shown that jump risks allow us to obtain credit spreads that are more realistic. However, according to the empirical studies on capital structure, another factor that affects credit spreads is the stationary leverage ratio of a firm. The present paper develops a simple structural model and incorporates both jump risks and the stationary leverage ratio to explain credit spreads. In comparison to the existing jump‐diffusion structural model, this model generates a larger credit spread, which is more consistent with observed credit spreads, especially for investment‐grade bonds. This paper also shows that jump frequency and size may be significant factors determining credit spreads for firms.