bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue responses assessed by intramuscular implantation
Authors: REID R. J. , WILSON D. F. , CHAU K. K. , HEITHERSAY G. S. , HEIJKOOP P. S. 
Published: September 2007

SummaryFreshly mixed polymerized Hydron root canal filling material, fully set AH26 and Teflon were implanted in the quadriceps muscle of guinea pigs and assessed his‐tologically at 2 days, 1, 2, 3, 12 and 26 weeks after implantation. All materials were characterized by peri‐implant fibrous connective tissue capsule formation. Von Kossa‐positive calcific material was observed at the implant‐tissue interface of Hydron implants. The amount of apparently calcified material increased with time. Inflammation was not a prominent tissue response for any of the test materials, nor was a foreign body giant cell response.
A Five‐year study of Hudron root canal fillings
Authors: REID R. J. , ABBOTT P.V. , MCNAMARA J. R. , HEITHERSHAY G. S. 
Published: September 2007

SummaryA prospective clinical and radiographic study was conducted in order to compare Hydron and laterally condensed gutta‐percha/AH‐26 root canal fillings. Paralleling technique periapical radiographs were taken pre‐operatively, postoperatively and at recall appointments at post‐treatment intervals of 6 months, 1 year, 2 years, 3 years and 5 years. Clinical examination at the recall appointments revealed no adverse signs or symptoms amongst all the patients who attended (mean attendance 44.5% at each interval). Radiographs were scored according to the periapical status of the treated root, and comparable bone healing rates were observed between the two root‐filling materials. Among the patients attending recall appointments, there were no radio‐graphic signs of failure of any of the 39 gutta‐percha/ AH‐26 root canal fillings. However, three of the 35 canals tilled with Hydron were classified as failures, and four required further assessment after the 5‐year recall appointment. This study indicated that Hydron and gutta‐percha/AH‐26 root canal fillings were well accepted but, on the basis of radiographic assessment, success with gutta‐percha/AH‐26 was more predictable.
Effect of thermal placement techniques on some physical properties of gutta‐percha
Authors: COHEN B. D. , COMBE E. C. , LILLEY J. D. 
Published: September 2007

SummarySome clinical techniques for the placement of gutta‐percha root fillings involve the application of heat. This study was undertaken to assess the effects of intracanal heating techniques on the following properties of gutta‐percha: coefficient of thermal expansion, softening temperature, phase transition temperature and organic content. Samples from each of four products were prepared by three different methods. The materials were studied by thermomechanical analysis, simultaneous thermogravmetry and differential thermal analysis, and by measurement of weight loss on ashing. It was shown that the techniques of gutta‐percha placement involving heating in the root canal caused reversible physical changes in the materials without any apparent change in chemical composition. The average coefficient of thermal expansion was 137 × 10−6/°C, the softening temperature was 55.5°C, there were two characteristic phase changes, and the organic content was 25%.
The physical properties of a new sealing cement
Authors: ONO K. , MATSUMOTO K. 
Published: September 2007

SummaryThis study was performed on a newly developed sealing cement, TS60, to evaluate its physical properties, namely sealing, setting time, compressive strength, solubility and ease of removal. It was compared with Temporary Stopping (GC Dental Industrial Corp., Tokyo, Japan), Eugedain (zinc oxide‐eugenol based material, Showa Yakuhin Kako Co. Ltd, Tokyo, Japan) and Cavit‐G (calcium sulphate based material, Espe Gmbh, Seefeld. Germany), which are typical commercially available sealing cements. The results of the study revealed that TS60 had excellent sealing properties, good compressive strength, low solubility, and was readily removable by heating and melting.
Dentine‐removing characteristics of K‐files energized by the Piezon‐Endo
Authors: BRIGGS P. F. A. , GULABIVALA K. , SETCI‐IELL D. J. 
Published: September 2007

SummaryThis in‐vitro study evaluated the pattern of dentine removal when a size 25 K‐file energized by the Piezon‐Endo was applied to flat surfaces of dentine under standardized conditiuons. The effects of power setting, interfacial force between file and dentine, direction of file oscillation and operator‐assisted movement were examined. Vinyl polysiloxane impressions of the instrumented surfaces revealed characteristic patterns consisting of a series of oblique crests, similar to those observed in a previous study using the Cavi‐Endo. Each crest was parallel to the next and separated by a relatively constant distance. These crests were disposed along the line of contact with the file. The Reflex microscope was used to determine the height width and separation of these crests.There were differences in the amount and pattern of dentine removal comparecd with the study on the Cavi‐Endo. When the file was held against the dentine surface using the minimum power setting and an interfacial force of 30 g, the pattern of dentine removal was very similar to that produced by the Carvi‐Endo. Increasing the power setting to the maximum recommended for endodontics produced a slight but statistically non‐significant increase in dentine removal. Further increase of the power setting to the absolute maximum produced significantly deeper and wider areas of dentine removal by the apical part of the file. In marked contrast to the Cavi‐Endo, increasing the interfacial force from 30 to 60 g resulted in a significantly greater amount of dentine removal by the coronal part of the file, but there was no reduction in the effect of the apical part of the file.The superimposition of operator‐induced movement of the file greatly increased the amount of dentine removal as demonstrated by the coalescence of crests to form deep grooves. The grooves tapered relatively evenly, except apically, where the taper increased and the grooves terminated in a point. The crestal pattern would be observed to a variable degree on some of the specimens. The total amount of dentine removed in the ‘operator‐assisted’ groups appeared to be much greater than that in the Cavi‐Endo study.
Microbiological evaluation of the efficacy of chlorhexidine in a sustained‐release device for dentine sterilization
Authors: HELING I. , SOMMER M. , STEINBERG D. , FRIEDMAN M. , SELA M. N. 
Published: September 2007

SummaryThe aim of this in‐vitro study was to evaluate the effect of chlorhexidine in solution and in a sustained‐release device as an intracanal medication. Hollow cylindrical dentine specimens prepared from bovine incisors were incubated with Streptococcus faecalis for a period of 3 weeks. The intracanal medicaments tested were 0.2% chlorhexidine gluconate solution (CM), chlorhexidine in a sustained‐release device (1.2 mg) (SRD), camphorated paramonochlorophenol (CMCP), and a control (no medication). Each medicament was introduced into the lumen of one dentine specimen and incubated for 5 min. 24 h,48 h or 7 days at 3 7°C. The bacteriological samples were taken by shaving the dentine inside the lumen with dental burs ranging in size from ISO 023–033. The dentine powder was collected in test‐tubes containing growth medium and incubated for 24 h. The optical density of the medium was recorded by means of a spec‐trophotometer at a wavelength of 540 nm. There was a statistically significant difference between the control group and all the medicaments tested.
Efficacy of a sustained‐release device containing chlorhexidine and Ca(OH)2 in preventing secondary infection of dentinal tubules
Authors: HELING I. , STEINBERG D. , KENIG S. , GAVRILOVICH I. , SELA M. N. , FRIEDMAN M. 
Published: September 2007

SummaryThis study was conducted to evaluate the efficacy of the antibacterial activity of Ca(OH)2 and a sustained‐release device containing chlorhexidine (SRD) in both sterilization and prevention of secondary infection of the root canal system. Bovine root dentine specimens previously incubated with Streptococcus faecalis were used in this experiment. Two different formulations of the SRD (differing in their cross‐linkage), Ca(OH)2 and normal saline (control) were evaluated. The degree of bacterial infection of the root canal was tested after incubation periods of 24 h, 72 h and 7 days with these medicaments. Their efficacy in preventing secondary infection after recontamination was tested after 72 h and 7 days. The results demonstrated that both formulations of the SRD significantly reduced the bacteria] population in the primary infected groups, as well as preventing secondary infection of the dentinal tubules in the recontaminated group. By contrast, Ca(OH)2 did not show any antibacterial activity, and failed to sterilize the dentinal tubules or prevent secondary infection after recontamination at the time periods examined.
Mandibular premolar with three root canals—two case reports
Authors: CHAN KAM , YEW SIU‐CHUN , CHAO SHOU‐YEE 
Published: September 2007

SummaryThe presence of three root canals in the mandibuiar premolar may sometimes be recognized when there is persistent postoperative discomfort following root canal therapy. This paper presents two cases of root canal treatment of mandibuiar premolars with three root canals including one mandibuiar first premolar and one mandibuiar second premolar. The possibility that there is more than one root canal in lower premolar teeth must be considered in the radiographic and clinical examination during root canal treatment.
Characterization of inflammatory cell infiltrate in dental periapical lesions
Authors: MARTON I. J. , KISS C. 
Published: September 2007

SummarySixty‐three dental periapical lesions were investigated in order to study the involvement of inflammatory and immunologic reactions in the pathogenesis and maintenance of chronic apical periodontitis. Of 61 wellpreserved specimens, 38 were classified as granulomatous, 3 as exudative periapical granulomas and 20 as periapical scars. The quantitative composition of T‐lymphocyte subpopulation and macrophages, the proportion of lgE‐producing cells compared with other immunoglobulin producing plasma cells, and the tissue distribution of IgE‐producing plasma cells compared with that of mast cells were determined in the granulomatous types of granulomas using immunofluorescent, immunohistochemical and enzymehistochemical methods. The results indicated a decreased ratio of helper/inducer versus cytotoxic/suppressor T‐lymphocytes, a remarkably high proportion of macrophages, a low frequency of IgE‐ producing plasma cells with different localization when compared with that of mast cells. These observations suggest that T‐lymphocytes and macrophages may play an important role in the complex events of tissue destruction and repair taking place in the periapical region.
Calcium hydroxide paste in the maxillary sinus: a case report
Authors: G.FAVA LUIZ ROBERTO 
Published: September 2007

SummaryA case is reported in which a perforation of the sinus floor of the maxillary sinus occurred with extrusion of a calcium hydroxide paste during routine root canal treatment of a maxillary premolar. All clinical manifestations are described as well as the results of a follow‐up evaluation.
Variations in the power output of the Piezon‐Master 400 ultrasonic endodontic unit
Authors: AHMAD M. , ROY R. A. , KAMARUDIN A. G. 
Published: September 2007

SummaryThe present study was undertaken to see if there was any variability in the power output of Piezon‐Master 400 ultrasonic files when driven using different generators, tranducers and file holders. The displacement amplitude of the oscillating tip of the file in air was used as a measure of the power output. The results showed that there was considerable variability in the power output of Piezon‐Master 400 ultrasonic files of similar size and length when driven using different generators, transducers and file holders. In consideration of this, it is recommended that a calibration device be incorporated in the ultrasonic unit so that the operator will have some knowledge of when the unit is working at its maximum efficiency.
A clinical evaluation of one and two‐appointment root canal therapy using calcium hydroxide
Authors: FAVA L. R. G. 
Published: September 2007

SummaryA clinical study using vital maxillary central incisors was performed to evaluate the incidence of postoperative pain after root canal treatment in one‐ or two‐appointments using a calcium hydroxide‐containing root canal sealer. No differences were observed between the two groups.
Evaluation of the antimicrobial effectiveness of citric acid and sodium hypochlorite on the anaerobic flora of the infected root canal
Authors: GEORGOPOULOU M. , KONTAKIOTIS E. , NAKOU M. 
Published: September 2007

SummaryThis study was designed to evaluate the antimicrobial effectiveness of 25% citric acid, compared with 2.5% sodium hypochlorite, after time intervals of 5, 15, 30 and 60 min. Anaerobic bacterial species were isolated from infected root canals and categorized according to Gram stain as Gram‐positive cocci, Gram‐negative cocci, Gram‐positive rods and Gram‐negative rods. The experimental method used was similar to that proposed by the German society for Hygiene and Microbiology (DGHM) with slight modifications. Testing revealed that citric acid does demonstrate anti microbial properties against anaerobic bacteria, especially against cocci, but it is less effective than 2.5% sodium hypochlorite.
Assessment of coronal leakage in teeth root filled with gutta‐percha and a glass ionomer root canal sealer
Authors: TIDSWELL H. E. , SAUNDERS E. M. , SAUNDERS W. P. 
Published: September 2007

SummaryThe effect on coronal leakage of the use of either a single gutta‐percha cone or cold lateral condensation of gutta‐ percha, with a glass ionomer sealer cement was studied. In addition, the effect of the removal of the smear layer was also determined. Eighty‐eight single‐rooted teeth were prepared chemomechanically using hand files, with the balanced force technique. Lubrication was provided by either Hibiscrub (maintaining the smear layer) or an EDTA ‐containing paste (to remove the smear layer). Copious irrigation was carried out with 2.2% sodium hypochlorite.The teeth were allocated randomly to four groups of 20 teeth each, the remaining eight teeth served as controls. Two groups of teeth, one with and one without smear layer, were obturated with either a single gutta‐ percha cone or cold laterally condensed gutta‐percha, with Ketac Endo as the sealer. The teeth were stored for 6 weeks, thermocycled, and the extent of coronal leakage determined for each group after immersion in India ink for 90 h. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent. Linear measurement of maximum dye penetration was recorded. The mean depth (+ SD) of leakage for the groups in which the smear layer was left intact was 1.68mm (+0.38) for the single cone (Al) and 2.29 mm (+ 1.58) for lateral condensation (Bl). When the smear layer was removed the mean depth of leakage For the single cone group (A2) was 2.04 mm (+ 0.73) and 2.37 mm (+ 1.70) for the laterally condensed group (B2).There was no significant difference in coronal leakage between the groups (P>0.05).
Effect of addition of hyroxyapatite on the physical properties of IRM
Authors: OWADALLY I. D. , FORD T. R. PITT 
Published: September 2007

SummaryThe aim of this study was to evaluate the effect of adding 10% and 20% hydroxyapatite (HAP) to Intermediate Restorative Material (IRM) on physical properties such as working time, setting time, compressive strength and disintegration rate. The working and setting times were determined by an indentation method. The ISO recommended method was used to determine compressive strength. The rate of disintegration in vitro was evaluated in buffered sodium citrate at pH 4.5, 5.8, buffered phosphate at pH 7.0 and in bovine serum (pH 6.8), and examined using a replica method and scanning electron microscopy. Kalzinol and EBA were used as control materials for the disintegration experiment. IRM had longer mean working (4 min 43.5 s) and mean setting (6 min 28.5 s) times than IRM + 10 or 20% HAP (P<0.001), the mean reductions being 16% and 9% for IRM + 10% HAP, and 29% and 19% for IRM + 20% HAP, respectively. IRM had a greater compressive strength (68.5 MPa, P<0.01) than IRM + 10% HAP (65.0 MPa) or IRM + 20% HAP (60.0 MPa, P<0.001). Kalzinol, IRM + 10% HAP and IRM + 20% HAP were found to disintegrate after 8 weeks in buffered phosphate and in bovine serum. In contrast, IRM and EBA showed no noticeable signs of disintegration after 6 months in the same media. The physical properties of IRM + 10% HAP and IRM + 20% HAP were reduced compared with IRM but the reductions were not considered to be of clinical significance.
Fluid transport and dye penetration along root canal fillings
Authors: WU M‐K. , DE GEE A. J. , WESSELINK P. R. 
Published: September 2007

SummaryDye penetration along root canal fillings may be hindered by the presence of entrapped air. In this study, the sensitivity of a dye penetration method was compared with that of a fluid transport model. Sixty root sections from human maxillary central incisors were prepared and obturated by a modified technique to ensure a slight amount of leakage, and divided into three equal groups. Twenty root sections were first mounted in a fluid transport device and assessed for fluid transport under 10 kPa (0.1 atm.) pressure. Another 20 root sections were mounted in the same device before being subjected to air transport under the same pressure. The remaining 20 root sections were not exposed to fluid or air transport. Then, all the 60 root sections were assessed for penetration of a 2% methylene blue solution. The results showed that fluid transport was a much more sensitive method of detecting voids along root canal fillings than dye penetration. After fluid transport for 3 h under low pressure, to eliminate entrapped air, dye penetrated significantly deeper than without previous fluid transport, which suggested that entrapped air in voids along the root canal filling prevented dye penetration.
Irritating effect of formocresol after pulpectomy in vivo
Authors: YAMASAKI M. , NAKAMURA H. , KAMEYAMA Y. 
Published: September 2007

SummaryA study was carried out to investigate the effect of formocresol (formalin‐creosote) on the periapical tissue after pulpectomy in rats. A pulpectomy was performed on the mesial root of the right mandibular first molar, and, in group A, a paper point containing saline was inserted into the root canal. In group B, a paper point containing formocresol was inserted, and in group C, a drop of formocresol was applied and a paper point containing formocresol was inserted into the root canal. The periapical tissue was examined histologically and histometrically at 3, 7, 14, and 28 days after insertion, and the inflammatory cells and fibroblasts in the apical granulation tissue were also counted. Histologically, in group A, the inflammation observed was slight at 14 and 28 days, while in groups B and C, a moderate inflammation remained. Histometrically, the area of the apical periodontal ligament in groups B and C was increased significantly compared with that in group A at 14 and 28 days. The inflammatory cell count in groups B and C increased significantly compared with that in group A at 7, 14, and 28 days, whereas the flbroblast count in Groups B and C decreased compared with that in Group A at 7, 14, and 28 days. These results demonstrate that formocresol delayed the healing of periapical tissue after pulpectomy.
Prescribing endodontic retreatment: towards a theory of dentist behaviour
Authors: KVIST T. , REIT C. , ESPOSITO M. , MILEMAN P. , BIANCHI S. , PETTERSSON K. , ANDERSSON C. 
Published: September 2007

SummaryThe large variations observed in dentists' management of periapical lesions in endodontically treated teeth suggest that disease concepts used in clinical practice should be investigated. In the present study it was hypothesized that dentists regard various periapical conditions as different stages on a health continuum. Variations could then be regarded as the result of the individuals selection of differing cut‐off points for prescribing retreatment.The hypothesized decision‐making model was tested using dental students in Amsterdam (Holland), Gothenburg (Sweden) and Pavia (Italy). The students were shown six simulated cases among which the quality of root filling seal and presence of post and crown were systematically varied. For each case, management of five periapical conditions was assessed. Five options were offered: no therapy, wait‐and‐see, nonsurgical retreatment, surgical retreatment, and extraction. For each examiner and case a ‘retreatment preference score (RPS)’ was established.The investigation showed large interindividual variations in RPS. A statistically significant higher mean RPS was seen among students in Pavia compared with students in Amsterdam and Gothenburg. Among all observers and cases it was found that if retreatment was proposed for a certain size of lesion, retreatment was subsequently selected for all larger lesions.The experiment gave evidence in support of the proposed hypothesis. The data also suggest that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of the original treatment.
A new non‐instrumental technique for cleaning and filling root canals
Authors: LUSSI A. , MESSERLI L. , HOTZ P. , GROSREY J. 
Published: September 2007

SummaryThe aim of this in vitro study was to test the ability of a novel non‐instrumental technique to prepare and obturate root canals. Cleaning of the root canal system was achieved with a device which was able to develop, under reduced pressure, controlled cavitation. The same device was used for proper drying and subsequent obturation of the root canal system. A total of 55 freshly extracted molars with 120 canals were treated either by the step‐back technique and lateral condensation of gutta‐percha and AH26 as a sealer or by the new device. The teeth were then sectioned horizontal to the long axis of the root canal and examined by light microscopy. The cross‐sectional area, area with residual pulpal tissue and voids were assessed morphometrically. Overall, the treatment with the new device resulted in similar cleanliness and obturation quality when compared with the control group. Total treatment time using the new non‐instrumental technique, however, was less than half of that using hand instrumentation.