bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of leukotriene C4 in human periradicular lesions
Authors: COTTI E. , TORABINEJAD M. 
Published: September 2007

SummaryThe purpose of this study was to determine the concentration of leukotriene C4 (LTC4), a potent inflammatory mediator, in human symptomatic and asymptomatic periradicular lesions. Periradicular lesions from each of six asymptomatic and symptom‐atic patients were obtained. Six pulps from unerupted third molars served as the negative controls, six samples of chronically inflamed gingival tissues served as the positive controls. All samples were immediately frozen in liquid nitrogen. The concentration of LTC4 was determined by reverse‐phase high‐pressure liquid chromatography. Representative samples from each group were fixed in formalin, sectioned and stained with haemotoxylin and cosin. The concentrations of LTC4 found in the periradicular lesions were signifi‐cantly higher than those in uninflamed pulpal tissue (P=0.027). However, no statistically significant difference was found between the concentration of LTC4 in the periradicular lesions of the symptomatic patients and those found in the asymptomatic patients and in the samples of the chronically inflamed gingival tissue (P>0.05).This data would suggest that among other inflam‐matory mediators, LTC4 participates in the patho‐genesis of human periradicular lesions.
Retreatment decision making by a group of general dental practitioners in Germany
Authors: HÜLSMANN M. 
Published: September 2007

SummaryThe aim of this study was to evaluate whether retreatment of root fillings was judged necessary or not and which kind of retreatment was preferred among a group of general dental practitioners in Germany. A questionnaire comprising 19 cases of endodontically treated teeth with different case histories and several treatment options was sent to all general practitioners in Göttingen (Germany). The cases included teeth with periapical radiolucencies, pain, apical resorption, under‐ and overfilling, and unfilled root canals. Results obtained from 43 questionnaires returned indicate that non‐intervention or further radiographic monitoring were preferred by the majority of general practitioners in 10 of 19 cases, even in the presence of periapical pathosis. Only five cases were judged to require conservative endodontic retreatment and, in four cases, root resection. The results revealed large inter‐ and intra‐individual discrepancies in the estimation of endodontic retreatment need.
Radiographic simulation of a periapieal lesion comparing the paralleling and the bisecting‐angle techniques
Authors: FORSBERG J. , HALSE A. 
Published: September 2007

SummarySixty apical areas of single‐rooted teeth were examined in this study. A simulated periapical lesion was produced using an acrylic sphere (diameter 2.0 mm), the surface of which was covered with a thin layer of zinc cement. The sphere was placed in close contact with the apical foramen using a thin orthodontic wire inserted into the apical portion of the root canal. The correctly adjusted parallel projection depicted the simulated lesion with a very low degree of error. Overangulation of the central beam with maintenance of parallelism between tooth and film resulted in a moderate degree of magnification.When correctly adjusted, the bisecting‐angle technique produced images with almost the same accuracy as the paralleling technique. Over‐angulation resulted in most images showing a reduced size of the simulated lesion. Moderate under‐angulation most often recorded the correct dimension of the globe. In some cases a magnified image of the sphere was produced. Generally, this was associated with a palatally curved root. The investigation thus clearly indicated that the paralleling technique provides the most reliable information about the extent of a pathological process.
A model system for evaluating filing technique
Authors: LUMLEY P. J. , WALMSLEY A. D. , HARRINGTON E. , MARQUIS P. 
Published: September 2007

SummaryThe aim of this study was to develop a model system to demonstrate the pattern of load and how much is applied. A lower molar was mounted on a beam and attached to a mandibular phantom head jaw. A strain gauge fitted to the beam allowed loading of the molar to be recorded, during root canal preparation. Ten operators were asked to instrument the distal root canal; after preparation the operators were shown a graphical representation of the loads applied. This formed the basis of discussion and instruction in filing technique. The operators then repeated the filing. The results showed that prior to instruction operators used a push‐pull motion, applying a constant lateral force to the canal wall. After instruction and discussion of the graphical representation of the loads applied the stroke rates used were slower and loads applied were higher (two‐sample t‐test, n=10, P<0.01). The experiment was repeated 1 year later and this showed that the change in technique had been retained. In conclusion, this model system allows visual feedback to the operator and can be used as an aid to teaching filing technique.
Allergy to sodium hypochlorite during root canal therapy: acase report
Authors: ÇALIŞKAN M. K. , TÜRKÜN M. , ALPER S. 
Published: September 2007

SummarySodium hypochlorite (NaOCl), is the most popular irrigation solution used in root canal treatment but it is known to be an irritant to vital tissues. There have been many case reports dealing with toxic effects of this material. Although the allergic potential of NaOCl has been described in the medical literature, only one case of known hypersensitivity to NaOCl has been reported in the dental literature. In this paper a case is presented, describing both local and systemic adverse tissue reactions, caused by an allergic response, after NaOCl irrigation.
Cytotoxicity studies of dental restorative materials using human periodontal ligament cells in vitro
Authors: ADAMS A. M. , SOAMES J. V. , SEARLE R. F. 
Published: September 2007

SummaryA model that simulates conditions of clinical practice In vivo and allows extended exposure of test cells to test substances, was evaluated In vitro by screening the toxicity of seven dental restorative cements. Millipore filter discs, 0.45 μm pore size, or preserved dentine slices were used as diffusion barriers between test cells and test substances. Cytotoxicity was assessed by estimating cell loss from monolayers and by evaluating cytopathic changes in cultured cells. After 24 h exposure to the test materials results were in general agreement with reported observations from similar studies. However, extended exposure to composite resins gave rise to severe cytotoxicity, which has not been reported previously. In addition, monitoring of cultures by inverted microscopy demonstrated attempts at recovery in damaged monolayers with viable cells migrating and proliferating into areas of earlier cell loss. This supports observations In vivo of transient pulpal injury associated with the corresponding materials.
A morphometric analysis of the cross‐sectional area of dentine occupied by dentinal tubules in human third molar teeth
Authors: DOURDA A. O. , MOULE A. J. , YOUNG W. G. 
Published: September 2007

SummaryThe number and the mean percentage tubular cross‐sectional area of dentinal tubules per square millimetre were calculated in specimens of coronal dentine of 13 intact human third molar teeth from patients 18 to 28 years of age. The dentine was fractured at various known distances from the dentino‐enamel junction. Near the dentino‐enamel junction the number of tubules per square millimetre was 22 000 and the mean tubular cross‐sectional area was 3.6%. Midway between the pulpal wall and the dentino‐enamel junction the number of tubules was 37000 mm−2 and the mean tubular cross‐sectional area was 6.2%. Close to the pulp the number of dentinai tubules was 48000 mm−2 and the mean cross sectional area of tubules was 10.2 percent. The number of tubules per square millimetre more than doubled and the area occupied by tubules increased threefold from the dentine close to the dentine ‐enamel junction, to that close to the pulp. These differences in tubular patterns at different depths in dentine are clinically significant in dentine permeability, the treatment of traumatized teeth, and pain transmission in dentine.
Physical mechanisms governing the hydrodynamic response of an oscillating ultrasonic file
Authors: ROY* R. A. , AHMAD* M. , CRUM L. A. 
Published: September 2007

SummaryUltrasonically driven vibrating files are known to enhance the efficiency of root canal debridement. This paper presents a phenomenological view of the hydrodynamic response of an oscillating ultrasonic file and the relationship between the file response and various physical factors such as file size and curvature, file surface properties, file velocity amplitude, root canal geometry, and the type of irrigant. Relevant hydrodynamic properties include the propensity of a file to produce stable and transient cavitation, steady streaming, and cavitation microstreaming.These relationships were explored by experiment. Sonoluminescence was employed as an indicator of transient cavitation activity and photographic analysis was utilized as a means for detecting steady streaming, microstreaming, and stable cavitation. Measurements failed to indicate any strong correlation between registered driving power and the propensity to produce transient cavitation. Files that were pitted or possessed salient edges were very effective at generating transient cavitation. When observed, transient cavitation activity generally occurred near the tip of the straight file, provided the wall‐loading did not inhibit file motion. In all cases studied, steady streaming and stable cavitation were observed to varying degrees, depending on the amount of file to wall contact. Stable cavitation was probably enhanced by the addition of moderate amounts of dissolved gas into the irrigant. Although the imposition of file–wall contact served to inhibit the production of transient cavitation, this action had relatively little effect on the ability of a file to produce a nominal level of streaming, microstreaming, and stable cavitation.The relationship between these hydrodynamic properties and the process of root canal debridement is addressed. Observations suggest that it is not prudent to ascribe enhanced cleaning effects to any one phenomenon, for it is likely that several factors are involved to varying degrees depending on the local conditions of application.
In vitro evaluation of apical leakage of root canal fillings after in situ obturation with thermoplasticized and laterally condensed gutta‐percha
Authors: VEIS A. A. , MOLYVDAS I. A. , LAMBRIANIDIS T. P. , BELTES P. G. 
Published: September 2007

SummaryThe purpose of this investigation was to compare In vitro the sealing ability of root canal treatments performed In situ with injected thermoplasticized gutta‐ percha compared with the lateral condensation technique. Thirty single‐rooted teeth with straight canals, due for extraction For orthodontic or periodontal reasons were prepared using a step‐back technique. Teeth were then divided randomly into groups A and B and obturated, respectively, with the sectional injection thermoplasticized gutta‐percha and the lateral condensation techniques. Teeth were extracted after 15 days, immersed in India ink for 3 days and the leakage was determined using area‐metric analysis. The roots were ground transversally and the root portion was incrementaly removed with successive steps of 250 μm each, up to the coronal level of the dye penetration. Every section was photographed with a stereoscopic microscope under the same magnification (×20); 310 photographs were taken. Measurements of the area covered by ink as well as the whole cross‐sectional area of the canal were made from each photograph with the aid of a digitizing computer.The measurements were subjected to non‐parametric statistical analysis. No significant difference was found (P>0.05). The technique of lateral condensation proved to be better in the first five sections (1.2 mm from the foramen) while thermoplasticized gutta‐percha technique was superior in the rest of the root canal.
Dentine tubule infection and endodontic therapy implications
Authors: OGUNTEBI B. R. 
Published: September 2007

SummaryA critical review of the literature suggests that the microenvironment of dentinal tubules appears to favour the selection of relatively few bacterial types irrespective of the aetiology of the infection process; coronal dental caries or pulpar necrosis. These bacteria may constitute an important reservoir from which root canal infection and reinfection may occur following pulp necrosis or during and after endodontic treatment. Previous studies of this microflora have utilized microbiological culture techniques which need to be supplemented by those that allow In situ demonstration as well as identification of the bacteria. Newer treatment strategies that are designed to eliminate this microflora must include agents that can penetrate the dentinal tubules and destroy these microorganisms, since they are located in an area beyond the host defence mechanisms where they cannot be reached by systemically administered antimicrobial agents.
Sealing properties of Ketac‐Endo glass ionomer cement and AH26 root canal sealers
Authors: DE GEE A. J. , WU M‐K. , WESSELINK P. R. 
Published: September 2007

SummarySealing capacity, setting shrinkage and setting time of a recently introduced glass ionomer cement Ketac‐Endo were compared with that of a conventional sealer AH26. Sixty half‐cylinders, 8 mm long, 4 mm in diameter, made from fresh bovine root dentine, had their smear layer removed before being cemented together while separated by 1‐mm spacers. This resulted in a group of 15 cylinders cemented with Ketac‐Endo and a similar group with AH26. After coating the lateral surface with nail varnish, one end of each cylinder was connected with a tube filled with water under 120 kPa (1.2 atm) pressure. At the other end the fluid leaking through the cemented interface of the cylinders was measured by displacement of an air bubble in an attached standard glass capillary. In this particular set‐up where the sealers were used in bulk between two opposing dentine surfaces, Ketac‐Endo leaked significantly more than AH26. After shear loading the cemented specimens, it was found that the area of adhesive failure was 88% for Ketac‐Endo, and 15% for AH26. The leakage pathways were most probably at the dentine‐sealer interface for Ketac‐Endo and through cohesive fractures in the sealer for AH26.
A study in vitro of threaded titanium pins used for retrograde obturation of root canals
Authors: DANIN J. , LINDER L. , RAMSKÖLD L. , SUND M.‐L. , STRÖMBERG T. , TELME I. , TORSTENSON B. 
Published: September 2007

SummaryThe microleakage of four retrograde filling materials was compared in vitro. Fifty‐three single rooted teeth were instrumentated and root filled with resin chloroform and gutta‐percha. The gutta‐percha cones were left extruding from the access opening. All teeth were apicected and retrograde fillings placed. The materials used were a non γ2 amalgam (Amalcap), a glass ionomer cement (ChemFil II), threaded titanium pins cemented with a glass ionomer cement (ChemFil II) and identical titanium pins cemented with a silicone material (Adheseal). After removal of the gutta‐percha with tweezers, a radioactive isotope solution was placed in the teeth. Extraradicular samples were taken at 3, 7, 28, 77 and 104 days. All retrograde fillings showed some microleakage. The group with titanium pins cemented with silicone showed the least leakage: significantly less than the teeth with glass ionomer cement (P < 0.01) and with amalgam (P < 0.01). No significant differences were found between other groups.
Resistance to fracture of endodontically treated premolars restored with new generation dentine bonding systems
Authors: HERNANDEZ R. , BADER S. , BOSTON D. , TROPE M. 
Published: September 2007

SummaryMOD cavities in 60 endodontically treated teeth were restored using six different methods. Copper rings were filled with commercial hard‐setting cement and the teeth were placed up to the level of the cemento‐enamel junction. The teeth were grouped according to restorative method, mounted in an Instron TT machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. All groups restored with the newer bonding system had higher resistance to fracture than those restored with an acid etch chemically cured composite resin technique. The groups restored with Den‐Mat Tenure Core Paste or a Variglass VLC base and Prisma APH were significantly stronger than the acid etch Concise restored teeth (P<0.05). No statistically significant differences were found between the other groups (P>0.05).
Association of specific bacteria with some endodontic signs and symptoms
Authors: GOMES B. P. F. A. , DRUCKER D. B. , LILLEY J. D. 
Published: September 2007

SummaryAlthough a wide range of bacterial species has been isolated from infected dental root canals it remains necessary to determine whether any particular group of such bacteria is associated with specific endodontic symptoms and clinical signs. In this study 30 root canals were examined microbiologically; of these, 14 were associated with pain, 20 with tenderness to percussion, 23 presented with wet root canals, seven with swelling, five with purulent exudate and four with a sinus. Clinical and microbiological correlation was observed particularly with regard to pain where anaerobes were isolated from 93% of painful canals and only from 53% of painfree canals. The former yielded means of 2.5 anaerobic species and 1.6 facultative species per canal, compared with 1.5 and 2.4 in painfree canals. Prevotella spp. were isolated from 64.2% of painful canals and 12.5% of painless canals (P<0.01) similarly, peptostreptococci were isolated from 71.4% of painful and 31.3% of painless canals (P<0.05). It was concluded that a significant association exists between pain and the presence of Prevotella and Peptostreptococcus spp. in dental root canals.
Leakage of four root canal sealers at different thicknesses
Authors: WU M‐K. , DE GEE A. J. , WESSELINK P. R. 
Published: September 2007

SummarySealers play a key role in sealing the root canal system. Fluid transport under a headspace pressure of 50 kPa (0.5 atm) through four sealers, AH26, Ketac‐Endo, Sealapex and Tubli‐Seal at a thickness of 0.05, 0.25 or 3 mm, was determined using 240 standard bovine root sections which were obturated with either sealer only or sealer combined with standard gutta‐percha cylinders. AH26 and Sealapex sealed more tightly than Ketac‐Endo or Tubli‐Seal when used without gutta‐percha; AII26, Ketac‐Endo, and Sealapex sealed more tightly than Tubli‐Seal when the sealer layer was 0.25 mm thick, while Ketac‐Endo sealed more tightly than the other three sealers when the sealer layer was 0.05 mm thick. These findings indicate that the thickness of the sealer layer influences the sealing ability of a root canal filling.
Influence of sodium hypochlorite on the permeability and structure of cervical human dentine
Authors: BARBOSA S. V. , SAFAVI K. E. , SPÅNGBERG L. S. W. 
Published: September 2007

SummaryThe effect of 5% sodium hypochlorite and 35% hydrogen peroxide on dentine samples in vitro was investigated. It was demonstrated that both 5% NaOCI and 35% H2O2 depletes the dentine, which can be recorded as weight loss. Sodium hypochlorite removes approximately 14% of dry weight from dentine samples in 24 h; hydrogen peroxide is half as destructive.The hydraulic conductance (Lp) of dentine after treatment with NaOCI is increased over 100%. It is suggested that the use of high concentrations of sodium hypochlorite during root canal treatment may negatively affect the integrity of the root canal wall thereby allowing increased access of caustic bleaching fluids to cervical vital tissues.
Ultrasonic root‐end preparation Part 2, Microleakage of EBA root‐end fillings
Authors: SAUNDERS W. P. , SAUNDERS E. M. , GUTMANN J. L. 
Published: September 2007

SummaryThe effect of three methods of root‐end preparation, following apical resection, on the apical seal of root‐end fillings, was studied in vitro. Root canals of 116 single‐rooted teeth with mature apices were prepared chemo‐mechanically and obturated with gutta‐percha and sealer. The root ends were resected with a diamond bur under water coolant and were prepared as follows: group I a size 010 round bur was used to prepare an apical cavity 2–3 mm down the long axis of the root; group II treatment as per group 1 followed by a 60‐s rinse with a solution of 10:3 (10% citric acid: 3% Fe2Cl3); and group HI an ultrasonic retrotip was used to prepare a 2–3 mm deep apical cavity. The root end was restored with an EBA cement. Apical leakage was determined using India ink after 7 days and 7 months. The teeth were demineralized, rendered transparent and linear dye penetration was recorded. Results showed that there was no significant difference in leakage between the groups at each time interval (P>0.05) but there was increased leakage after 7 months (P<0.01). Cracking of the root surface was seen most often with the ultrasonically prepared roots (P<0.001).
Efficacy of sterilization of endodontic files after autoclaving in a synthetic sponge
Authors: BOYD K. S. , SONNTAG K. D. , CRAWFORD J. J. 
Published: September 2007

SummaryA common way of sterilizing endodontic files for clinical use is to insert them into synthetic sponges. The files are sterilized in the sponge, and the sponge is then used on the patient tray for ease of file retrieval. The ability to sterilize the files in a sponge has been questioned. The purpose of the present investigation was to evaluate the sterility of files and spore strips following autoclaving in a sponge. Commercial spore strips and contaminated endodontic files were inserted into sponges, sealed in sterilization pouches and autoclaved. The spore strips and the files were removed from the sponge and cultured for growth of microorganisms. Results show that no microbes were cultured from spore strips or contaminated files after autoclaving them in the sponges sealed in autoclave pouches. These results indicate that the insertion of files into the sponges used in this study does not obstruct the autoclaving process.
Torsional properties of stainless steel Canal Master U and Flexogates
Authors: CAMPS J. J. , PERTOT W. J. 
Published: September 2007

SummaryThe purpose of this study was to evaluate and compare the torsional properties of Flexogates and Canal Master U instruments. Torsion and bending tests were performed on both designs of instrument according to ANSI/ADA specification number 28 criteria and standards. Ten instruments of each size, sizes 25 to 50 were used for each test. Four parameters were measured: the moment at failure, the rotation at failure, the separation point at failure and the bending moment at a 45° angle. Both instruments satisfied ANSI/ADA standards for rotation at failure and bending moment. Canal Master U satisfied ANSI/ADA standards for moment at failure in all sizes except 45 and 50. Flexogates did not satisfy these standards in all sizes except 50. Flexogates separated at the end of the shaft whereas Canal master U separated just behind the cutting head. Both instruments showed favourable physical properties for preparing root canals.