bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of long‐term calcium hydroxide treatment in avulsed teeth — an in vivo study
Authors: DUMSHA T. , HOVLAND E. J. 
Published: September 2007

SummaryCalcium hydroxide has been advocated for use in avulsed teeth as a temporary dressing in an attempt to prevent or inhibit external resorption. However, there have been no long‐term histological studies that have examined gutta‐percha versus calcium hydroxide treatment in avulsed teeth. The purpose of this study was to determine the long‐term therapeutic effect of calcium hydroxide therapy in avulsed teeth. Six adult macaca monkeys were anesthetized and all four maxillary incisors were extracted and bench‐dried for 25 min. The teeth were replanted and splinted with composite for approximately 2 weeks. Each animal served as its own control and the teeth were accessed, instrumented, and filled with either Ca(OH)2 or gutta‐percha and AH26 cement. All access openings were filled with composite. The Ca(OH)2 was replaced twice during the experimental period (approximately every 8 weeks). The animals were killed between 5 and 7.5 months postavulsion. The teeth were removed, sectioned, and examined histologically by two examiners. The results of the histological evaluation of external resorption indicated that there were no statistically significant differences in resorption indices between the teeth obturated with gutta percha or with calcium hydroxide (P>0.05). Replacement resorption was the primary cause of root destruction and only a few histological sections exhibited evidence of inflammatory resorption.
In vitro radicular temperatures produced by injectable thermoplasticized gutta‐percha
Authors: WELLER R. N. , KOCH K. A. 
Published: September 2007

Summary In vitro temperatures produced in the root canal and on the root surface were measured simultaneously as heated gutta‐percha was injected into the prepared canal. The canals were obturated with the Obtura II heated gutta‐percha system with temperature settings of 160, 185, and 200°C. The mean intracanal temperatures ranged from 40.21 to 57.24°C, whereas the mean root surface temperatures were recorded from 37.22 to 41.90°C for all three temperatures tested. The rise in temperature on the root surface was below the critical level of 10°C and should not cause damage to the periodontal ligament.
Single visit root canal treatment: incidence of postoperative pain using three different instrumentation techniques
Authors: FAVA L. R. G. 
Published: September 2007

SummaryA clinical study was carried out on nonvital maxillary central incisors to evaluate the incidence of postoperative pain following single‐visit root canal treatment using three different instrumentation techniques. Ninety teeth from 78 patients whose ages ranged from 14 to 63 years were selected and divided into three groups. Each group (30 teeth) was prepared by a different coronal‐to‐apical technique using different instrument movement depending upon the technique employed: modified double‐flared, crown‐downpressureless and balanced force techniques. No difference was observed in the incidence of postoperative pain among the groups.
Diagnostic confidence and the accuracy of treatment decisions for radiopaque periapical lesions
Authors: STHEEMAN S. E. , MILEMAN P. A. , van't HOF M. A. , van der STELT P. F. 
Published: September 2007

SummaryThe periapical radiograph is a tool used in the diagnosis of periapical bone pathology. Radiographic diagnosis might therefore influence endodontic treatment planning and the quality and the cost of dental health care. The hypotheses were tested that (1) the subjective prevalence of a lesion would be associated with the accuracy with which it is diagnosed, (2) ‘confident dentists’ would be as accurate in their diagnosis as ‘doubtful dentists’ and (3) the diagnostic confidence of dentists for the diagnosis of periapical pathology would not influence their treatment planning. It was found that the probability of an appropriate treatment decision increased when dentists were relatively confident about a diagnosis. The results showed, furthermore, that the accuracy of diagnostic decisions increased when the dentist's confidence about a particular decision was high. Ways to increase diagnostic accuracy of radiopaque periapical pathology are proposed as a result of this study.
The smear layer: a phenomenon in root canal therapy
Authors: ŞEN B. H. , WESSELINK P. R. , TÜRKÜN M. 
Published: September 2007

SummaryWhen the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the prescence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and if delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCI solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.
Pulpotomy of carious vital teeth with periapical involvement
Authors: ÇALIŞKAN M. K. 
Published: September 2007

SummaryTwenty‐six permanent vital molars with carious pulp exposures and periapical involvement presenting as radiolucencies or radiopacities on radiographic examination, in patients aged between 10–24 years, were treated using an atraumatic surgical technique with calcium hydroxide alone.The healing was evaluated using clinical and radiographic criteria: absence of clinical symptoms, sensitivity of the radicular pulp, formation of a hard tissue barrier in the exposed area, resolution of periapical involvement and no intraradicular pathosis radiographically. Assessed by these criteria, successful results were achieved in 24 teeth. The observation period following pulpotomy treatment was 16–72 months. The favourable results of this study demonstrate that pulpotomy treatment in teeth with cariously exposed vital pulps and with periapical involvement may be an alternative treatment to root canal therapy.
A 1‐year follow‐up study on leakage of four root canal sealers at different thicknesses
Authors: WU M.‐K. , WESSELINK P. R. , BOERSMA J. 
Published: September 2007

SummaryDetermination of leakage using a fluid transport model allows measurement of leakage in a longitudinal manner. Leakage of four sealers at three different thick‐ nesses in 225 bovine root sections, after storage in water for 1 year, was measured again using the same method‐ ology. The change in seal over time for each sealer was observed. The results after the second measurement showed that every sealer produced the best seal when the sealer layer was the thinnest. AH26, Ketac‐Endo and Tubli‐Seal showed a reduction in leakage over time and gave significantly less leakage than Sealapex (P<0.005). Sealapex showed sigdicantly more leakage after storing in water for 1 year (P<0.005). Therefore, the long‐lasting seal of sealer may, among other influencing factors, depend on the layer thickness and the solubility of the material.
Torsional and stiffness properties of nickel–titanium K files
Authors: CAMPS J. J. , PERTOT W. J. 
Published: September 2007

SummaryThe purpose of this study was to compare stiffness and resistance to fracture of four brands of nickel titanium K files. Instruments of sizes 15 to 40 were tested according to ANSI/ADA Specification No. 28. Resistance to fracture was determined by twisting and measuring the maximum torque and angular deflection at failure. Stiffness was determined by measuring the moment required to bend the instrument 45°. The permanent deformation angle remaining between the tip and the flutes of the instruments after bending ceased was also recorded. Nickel titanium K files satisfied and far exceeded specification standards for stiffness. They also satisfied and exceeded the standards for angular deflection at failure. They met or exceeded the maximum torque at failure standards in all sizes except for the size 40 of the Maillefer Niti, and the size 30 of the Mac Spadden Niti. Nickel titanium K files presented a null permanent deformation angle. Clinical studies are required to evaluate the influence of low bending moment on other properties such as breakage and canal transportation.
Machining efficiency of nickel‐titanium K‐type files in a linear motion
Authors: CAMPS J. J. , PERTOT W. J. 
Published: September 2007

SummaryThe purpose of this study was to compare, in vitro, the machining efficiency of four brands of nickel‐titanium files and two brands of stainless steel K‐type files. Instruments sizes 15 to 40 were tested in a linear motion simulating the clinical motion used to remove a file from the canal. The tips of the loaded files were in contact with a resin block. The load applied increased with file size. An indentation varnish caliper was used to measure the depth of the groove after 100 back‐and‐forward motions. The stainless steel instruments with a triangular cross‐section were more efficient than the stainless steel instruments with a square cross‐section. There was a significant discrepancy between the machining ability of the nickel‐titanium K files. The Maillefer instruments were the most efficient.
Associations of endodontic symptoms and signs with particular combinations of specific bacteria
Authors: GOMES B. P. F. A. , LILLEY J. D. , DRUCKER D. B. 
Published: September 2007

SummarySignificant associations have been reported between (a) specific bacterial species isolated from root canals and (b) between individual bacterial species and endodontic symptoms and signs. The prime objective of this study was to determine whether particular combinations of specific bacteria are associated with individual endodontic symptoms and signs. Seventy root canals were investigated microbiologically taking care to maintain the viability of obligate anaerobes, which accounted for 64% of the total species isolated, including Peptostreptococcus micros, Prevotella melaninogenica, Prevotella oralis, Eubacterium aerofaciens, Eubacterium lentum, Fusobacterium nucleatum, Prevotella buccae and Prevotella intermedia. Significant associations were found between individual clinical features and the following pairs of species: (a) pain (37 cases) and Peptostreptococcus spp./Prevotella spp., Peptostreptococcus spp./Prevotella melaninogenica, Pstr. micros/Prev. melaninogenica (all P < 0.01); (b) swelling (23 cases) and Pstr. micros/Prevotella spp. (P < 0.01); (c)‘Wet’canal (57 cases) and Prevotella spp./Eubacterium spp. (P < 0.01), Peptostreptococcus spp./Eubacterium spp. (P < 0.05). Thus data from this investigation suggests that statistically significant associations exist between individual endodontic symptoms and signs and particular combinations of specific bacteria.
The use of a radiopaque contrast medium in endodontic radiography
Authors: SHEARER A. C. , WASTI F , WILSON N. H. F. 
Published: September 2007

SummaryA series of in vitro studies were carried out to investigate the use and application of a radiopaque contrast medium in conventional periapical dental radiography for the diagnosis and evaluation of root canal systems. The water‐soluble radiopaque contrast medium was introduced into the root canals of 30 first permanent maxillary and 30 first permanent mandibular molar teeth. The radiographic images of these teeth with and without radiopaque contrast medium in the root canal systems were compared and contrasted. Further comparisons were made with the same teeth rendered transparent.The results indicate that by standardizing the diagnostic criteria the inter‐examiner reliability was in good agreement; it was independent of the radiographic technique used. The validity of the radiographs was enhanced by the use of the radiopaque contrast medium. The results confirm that, with the use of a radiopaque contrast medium, images of root canal systems are easier to read and interpret than plain radiographic images of root canal systems.The use of radiopaque contrast medium in endodontic radiography may be a valuable aid in the diagnosis and evaluation of root canal systems. This system would complement rather than replace plain radiography.
Adherence of Streptococcus gordonii to smeared and nonsmeared dentine
Authors: LOVE R. M. 
Published: September 2007

SummaryThe purpose of this study was to investigate the adherence of Streptococcus gordonii to smeared and non‐smeared dentine and to assess the influence of patent dentinal tubules on bacterial retention. In order to examine bacterial adherence, 10 non‐smeared (group 1) and 10 smeared samples (group 2) of outer root dentine were prepared from teeth exhibiting dentine sclerosis. Ten non‐smeared samples from inner coronal root dentine that did not exhibit sclerosis were prepared in order to study the influence of patent tubules on bacterial retention (group 3). Cells of the bacterium were radioactively labelled and an adhesion assay was performed. The number of bacteria adhering to the dentine surface was determined by scintillation counting. The results show that the number of bacteria adhering to both smeared and non‐smeared outer sclerotic dentine was low (0.3% of inoculum), and there was no significant difference between the groups (P > 0.3). A significantly higher number of bacteria was retained on the inner non‐smeared coronal root dentine (P < 0.0001) compared to groups 1 or 2. The results suggest that dentinal smear layers do not enhance or impede bacterial adherence to the dentine matrix. Dentinal surfaces with patent dentinal tubules retain more bacteria than a smeared surface.
Assessing apical deformation and transportation following the use of LightSpeedTM root‐canal instruments
Authors: KNOWLES K. I. , IBARROLA J. L. , CHRISTIANSEN R. K. 
Published: September 2007

SummaryThe LightSpeedTM root canal instrument is similar in design to the Canal Master instrument with the exception of being engine driven and fabricated from nickel‐titanium alloy. The purpose of the design of these instruments is to reduce apical transportation of the canal during cleansing and shaping procedures. Twenty extracted human molar teeth with roots of varying degrees of curvature were used in this study. A double exposure radiographic technique was used to assess the Presence or absence of apical transportation resulting between the initial instrument and the final instrument, a size 50 LightSpeedTM Only one of the 20 teeth examined exhibited apical transportation. Results of this study suggest that little or no apical canal transportation could be expected when curved canals are instrumented using the LightSpeedTM root canal instruments.
Penetration of smeared or nonsmeared dentine by Streptococcus gordonii
Authors: LOVE R. M. , CHANDLER N. P. , JENKINSON H. F. 
Published: September 2007

SummaryThe purpose of this study was to investigate the penetration of smeared and nonsmeared dentine by Streptococcus gordonii. Prepared human roots, grouped as either nonsmeared or smeared, were immersed in a suspension of S. gordonii cells for 3 weeks. The roots were then prepared for scanning electron microscopy and histological analysis. Dentine discs prepared from coronal dentine were grouped similarly. Using a fluid filtration apparatus, the hydraulic conductance (Lp) of each disc was determined before and after incubation with bacterial suspension. Scanning electron microscopy evaluation of the roots following infection with bacteria showed no change in the smear layer (P<0.0001). Histological sections revealed that bacterial penetration of all the nonsmeared samples had occurred, while nine out of 10 smeared samples showed no bacterial penetration (P<0.0001). The Lp of the nonsmeared discs was significantly reduced by 42% (P<0.0001) after bacterial penetration. However, the smeared samples revealed a 1% reduction in Lp which was not significant (P > 0.05). The results suggest that dentinal smear layers are an effective barrier to dentinal tubule invasion by S. gordonii.
Permeability, morphologic and temperature changes of canal dentine walls induced by Nd: YAG, CO2 and argon lasers
Authors: ANIĆ I. , TACHIBANA H. , MASUMOTO K. , QI P. 
Published: September 2007

SummaryThe permeability, temperature and morphologic changes of the wall of the root canal induced by Nd:YAG, CO2 and argon lasers were studied. The changes were evaluated according to the presence or absence of a smear layer. Root canals of 140 human single‐rooted teeth were enlarged using a step‐back technique. Permeability was evaluated by the extent of methylene blue dye penetration into the tubules. Temperature changes were measured using a thermovision system, and morphological changes were evaluated by scanning electron microscopy. Laser energy was delivered into the canal by means of a flexible optical fibre or metal tip. There were statistically significant differences in permeability between Iased groups with and without a smear layer in the cervical third of the root canal following lasing. In the middle third of the root canal, all three laser types induced permeability increases in groups with a smear layer. In the apical third, statistically significantly decreases in permeability were observed among C02 laser and Nd:YAG compared with control group (P<0.01). Rises in temperature ranged from a minimum of +10.1 °C (CO2 laser) to a maximum of +54.8 °C (argon laser). All three laser devices appeared capable of producing a glazed‐like surface and craters.
The effect of tubular penetration of root canal sealers on dye microleakage
Authors: ŞEN B.H. , PIŞKIN B. , BARAN N. 
Published: September 2007

SummaryAn in vitro study of a possible correlation between penetration of dentinal tubules by four root canal sealers and microleakage of external fluids into the canal was done using a dye leakage method and scanning electron microscopy. The root canals of 45 teeth were instrumented and the smear layer removed prior to obturation of root canals with gutta‐percha and one of four sealers: Diaket, Endomethasone, CRCS or Ketac‐Endo. The extent of leakage was scored after immersion in India ink for 72 h. The same specimens were also used for scanning electron microscopic evaluation. There was a statistical difference in leakage patterns between the groups (P<0.05). Diaket had lower microleakage scores than the other sealers (P<0.05). When the scores for penetration of sealers into the tubules were analysed, Ketac‐Endo demonstrated the least penetration (P<0.01). There appeared to be a converse relation between tubular penetration and dye leakage, but the correlation was not statistically significant (P<0.05).
Plasma catecholamine and haemodynamic responses to surgical endodontic anaesthetic protocols
Authors: GUTMANN J. L. , JR FRAZIER L. W. , BARON B. 
Published: September 2007

SummaryThe effects of varying clinically relevant patterns of anaesthetic‐vasoconstrictor combinations used for peri‐radicular surgery on plasma concentrations of catecholamines and haemodynamic responses was studied in the canine model. Five mongrel dogs were anaesthetized with sodium pentobarbital. A femoral canula was inserted to measure central blood pressure and an ECG was used to monitor heart rate and any associated arrhythmias. Femoral venous blood samples were drawn before initial injection and at 3 and 10 min after injections. Plasma catecholamine concentrations were determined using high pressure liquid chromatography (HPLC). Injection protocols used three time periods, 30, 60 and 90s, with solutions containing 1:100000 and 1:50000 adrenaline. No significant changes in heart rates or presence of arrythymias were noted over the experimental protocol. Catecholamine levels in pico moles mL‐1 were within the normal range at the 3‐min sample level. At the 10‐min sample time there was a more erratic range of concentrations, with most samples within the normal range. This may have been due to endogenous release of catecholamines in specific animals. The data identified trends in both the haemodynamic parameters and plasma catecholamine levels that can legitimately support the careful use of higher levels of a vasoconstrictor when patient profiles and surgical needs dictate.
Susceptibility of Actinomyces israelii to antibiotics, sodium hypochlorite and calcium hydroxide
Authors: BARNARD D. , DAVIES J. , FIGDOR D. 
Published: September 2007

Summary Actinomyces israelii has been repeatedly implicated as a cause of failure of endodontic therapy. This study investigated the antimicrobial effect of antibiotics as well as intracanal medicaments, sodium hypochlorite solution and calcium hydroxide, on this important pathogen. Growth of A. israelii was inhibited by low concentrations of antibiotics, yet high concentrations were not bactericidal for A. israelii over 1 week. When A. israelii was exposed for 2‐6 weeks at concentrations equivalent to clinical serum levels, the antibiotics were lethal. The results reveal a species ‐ specific antibiotic tolerance for A. israelii. Both sodium hypochlorite solution and calcium hydroxide were found to be highly eifective in killing A. israelii.
Effect of various irrigant and autoclaving regimes on the fracture resistance of rubber dam clamps
Authors: SUTTON J. , SAUNDERS W. P. 
Published: September 2007

SummaryRubber dam clamps are known to break during clinical use in endodontics. This in‐vitro study examined some of the variables which may contribute to the fracture. Stainless steel rubber dam clamps were subjected to various cleaning and autoclaving regimes and exposure to various solutions of sodium hypochlorite (NaOCl). Each clamp was examined after four cycles of cleaning and exposure to NaOCl. During environmental exposure to NaOCl, the clamp was stressed over a perspex rod to simulate placement onto the crown of a tooth. Clamps were examined after each test cycle visually and microscopically, or immediately after breakage. Results suggested that the fractures were because of a stress corrosion cracking phenomenon. There was evidence of intergranular and transgranular cracking of the metal. Corrosion spots were seen on the surface of the clamps and fracture occurred mainly through these spots. A number of recommendations to reduce breakage of clamps have been suggested.