bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature and surface changes of dentine and cementum induced by CO2 laser exposure
Authors: ANIĆ I. , DZUBUR A. , VIDOVIĆ D. , TUDJA M. 
Published: September 2007

SummaryThe thermal effects of a CO2 laser on the external root surface and inside the root canal were studied in vitro by means of computerized infrared (IR) thermography and a digital thermometer.One‐hundred‐and‐eighty tooth roots with single root canals were irradiated internally and externally with laser power set at 0.5,1,1.5,2,3 and 4 W. The laser was used in two operating modes: pulsed (pulse 0.5s) and continuous mode with exposure time of 10s.Under the conditions of this experiment, temperature rises of between 1.5 and 19.1°C at the external root surface and 1.5 and 12°C inside the root canal and horizontally across the sectioned root surface were recorded. The results obtained with IR camera showed a higher temperature on the external root surface than the digital thermometer during and after lasing the root canal.Scanning electron microscope (SEM) analysis revealed that even low laser energy significantly damaged the external root cementum surfaces.
Failure behaviour of fatigue‐tested post and cores
Authors: HUYSMANS M.‐C. D. N. J. M. , PETERS M. C. R. B. , VARST P. G. T. VAN DER , PLASSCHAERT A. J. M. 
Published: September 2007

SummaryEvaluation of die long‐term behaviour of restorations in clinical trials can be time‐consuming. A partial alternative to the clinical trial can be found in mechanical fatigue testing. The aim of this study was to evaluate the failure behaviour of post and core restored teeth when subjected to cyclic mechanical loading and to compare it with quasistatic failure. Eighty seven premolar teeth were restored with a titanium alloy post and an amalgam or composite core. Five to 21 days after restoration, the specimens were subjected to cyclic loading (frequency 5 Hz), at an angle of 45° to the long axis of the tooth. The load levels were 50,60,65 and 70% of mean quasistatic failure loads. The specimens were divided into three groups according to their survival time: short (S) (>104 cycles), intermediate (I) (104≥life>105 cycles) and long (L) (≥ 105 cycles). For both core materials failure behaviour changed after approximately 105 cycles, and the change was most marked for the composite group. Catastrophic fatigue failure consisted of core fracture in the amalgam group (three times) and of post fracture in the composite L group (four times). Three post fractures occurred at a site theoretically predisposed to fatigue failure. It was concluded that fatigue failure characteristics of post and core restorations may be very different from those of quasistatic failure. Therefore, in addition to quasistatic tests, fatigue tests are necessary, covering at least 105 load cycles.
The penetration of root canal sealers into dentinai tubules. A scanning electron microscopic study
Authors: OKŞAN T. , AKTENER B. O. , ŞEN B. H. , TEZEL H. 
Published: September 2007

SummaryThe purpose of this study was to evaluate the effect of smear layer on penetration of four root canal sealers into dentinai tubules.Sixty‐four, recently extracted, human maxillary and mandibular incisors were used. Following removal of the crowns, the pulps were extirpated and the root canals instrumented. The teeth were then divided into two groups. The teeth in the control group were irrigated with saline solution and the experimental group treated with EDTA and NaOCl. Each main group was then divided into four sub‐groups and the root canals Oiled with Diaket, N2 Universal, SPAD and Forfenan as recommended by the manufacturers. The teeth were split longitudinally and examined using scanning electron microscopy. A quantitative assessment was made of sealer penetration into the dentinai tubules in the coronal, middle and apical parts of each root canal.It was observed that the smear layer obstructed the penetration of the tubules by the sealers. However, in the experimental group, the penetration into dentinai tubules was better with Diaket, N2 and SPAD, than with Forfenan (P > 0.01).It was concluded that this penetration could be affected by physical and chemical properties of root canal illing materials.
In vitro cleaning ability of root canal irrigants with and without endosonics
Authors: CHEUNG G. S. P. , STOCK C. J. R. 
Published: September 2007

SummaryA variety of methods have been used to evaluate the cleanliness of root canals after endodontic preparation and irrigation. Few irrigation agents other than sodium hypochiorite (NaOCl) have been tested in conjunction with endosonics. The purpose of this study was to examine the cleaning ability of water, NaOCl, Hibiscrub and a biological washing liquid when used as intracanal irrigants, with and without endosonics. Two methods of evaluation were employed to assess the root canal cleanliness after endodontic preparation.A total of 56 teeth, divided into eight groups, were prepared manually using the step‐down technique. Each irrigating agent was used in two experimental groups, with and without endosonics. Two additional teeth which received neither instrumentation nor irrigation served as the controls. The teeth were split longitudinally and the state of cleanliness of the root canal was assessed by scoring the amount of stained organic debris and smear layer.It was demonstrated that the results of debris and smear layer scoring were significantly influenced by the type of irrigant and whether endosonics had been used. All agents exhibited similar cleaning ability when introduced manually. With endosonics, NaOCl yielded significantly less stainable debris (P < 0.05) than the other groups which showed no significant difference. The ability to remove the smear layer was enhanced, but at some distance short of the working length, by endosonics for all irrigants tested. None of the solutions tested was able to produce a canal wall that was free of smear layer.
Presence of natural killer cells in human chronic periapical lesions
Authors: KETTERING J. D. , TORABINEJAD M. 
Published: September 2007

SummaryNatural killer (NK) cells are lymphokl in nature and appear to kill target cells (neoplastic and virus‐infected cells) without apparent prior immunization. Ten human chronic periapical lesions were examined for the presence of these cells. The lesions were collected, frozen in liquid nitrogen, and sectioned. They were then stained with an indirect immunoperoxidase procedure for the presence of human NK ceils. Human tonsils and human periapical scar tissue were used as positive and negative controls. The results showed absence of NK cells in scar tissue and the presence of NK cells in tonsils and all samples of human periapical lesions. NK cells may play a defensive role in controlling root canal infections or, possibly, a role in its pathogenesis.
A comparison of endodontic treatment results at two dental schools
Authors: ØSRSTAVIK D. , HÖRSTED‐BINDSLEV P. 
Published: September 2007

SummaryEndodontic treatment results were assessed in a controlled clinical study in Arhus. Undergraduate students used either Kloroperka or AH26 as sealer in a randomized fashion. The findings were compared with the results from a previous study of identical design in Oslo, which involved Kloroperka, AH26 and ProcoSol. While Kloroperka performed slightly, but significantly less well than AH26 or ProcoSol in the Oslo study, no difference was found between Kloroperka and AH26 in the present study. The overall treatment results were poorer in Arhus than in Oslo, but this might be explained by a marked difference in the preoperative diagnoses and in the technical problems associated with the teeth selected for treatment. When results of endodontic treatment carried out at different locations are compared, variations in case selection and preoperative diagnoses must be corrected for in order to obtain an adequate basis for comparison.
Antibacterial properties of eight dental cements
Authors: COOGAN M. M. , CREAVEN P. J. 
Published: September 2007

SummaryThe antibacterial action of a light‐cured glass poly‐alkenoate Vitrebond and an adhesive resin luting agent Panavia Ex was investigated and compared with six previously tested dental cements. The bacterial cultures used were six strains of Streptococcus mutans, six of Streptococcus sanguis and six cultures of carious debris from carious lesions. A modification of the agar diffusion method was used to test the antibacterial action of freshly mixed cements. In addition the cements were allowed to set and their antimicrobial action was tested by incubation for 5 days in sucrose broth inoculated with the test cultures. All the freshly mixed materials had an antibacterial action. A two‐way analysis of variance and Tukey–Student range analysis showed that Vitrebond had a significantly greater zone of inhibition than Aquacem, IRM, Dycal. Dycal VLC, Ceramco and GC Elite (P=0.001). Freshly mixed Panavia Ex exhibited minimal antibacterial action. After 5 days the antibacterial properties of alt the cements were reduced.
Pulpal disease and bursts of periodontal attachment loss
Authors: HIRSCH R. S. , CLARKE N. G. 
Published: September 2007

SummaryProgression of periodontitis is currently thought to occur during bursts of activity, followed by periods of remission, when healing may occur. This concept contrasts with the older hypothesis that periodontitis was continuously, but slowly, progressive throughout life. At present, there is no proof of the conventional (microbiological) hypothesis which gives a major role to site‐specific bacteria in the initiation of bursts of attachment loss. An alternative hypothesis is presented in this paper which accounts for periodontal attachment loss by pathways that are independent of plaque. Severe lesions of the periodontium caused by pulpal pathoses (apical and retrograde periodontitis) are known to form at any level of the periodontium, not only at the root apex. When these lesions cause destruction of the periodontal tissues at the alveolar crest, and when plaque, calculus and gingivitis are also present, an endodontic origin is rarely suspected. Three pathways are proposed to account for the development of localized periodontal attachment loss consequent to pulpal disease. This hypothesis accounts for the sudden deterioration of periodontal sites under regular review, the strict localization of alveolar defects with normal alveolar bone immediately adjacent, the presence of site‐specific bacteria (secondary colonizers of deep pockets) which cannot cause disease when transferred to healthy sites, and the antibody responses directed against them.
Root canal treatment on patients with HIV infection
Authors: COOPER H. 
Published: September 2007

SummaryPatients attending a dedicated dental clinic during the previous 24 months were assessed for the success of root canal treatment. Two groups, totalling 48 patients, had root canal treatment to 57 teeth performed by one operator. All treatment was carried out without antibiotic prophylaxis over two or more appointments.Patients with HIV infection had root canal treatment to 40 teeth. Sixteen patients in the control group had root canal treatment to 17 teeth. Short‐term success was determined by follow‐up appointments 1–3 months following obturation.No complications were experienced in either group, except with one HIV infected patient. The results of this clinical study indicate that root canal treatment can be carried out following standard procedures and without antibiotic prophylaxis.
Low surface tension calcium hydroxide solution is an effective antiseptic
Authors: BARBOSA S. V. , SPANGBERG L. S. W. , ALMEIDA D. 
Published: September 2007

SummaryThe antimicrobial effects of a saturated calcium hydroxide solution, and in combination with 10% and 20% detergent, were evaluated on Streptococcus faecalis. Strepto‐coccus sanguis, Streptococcus mutans, Streptococcus salivarius, Neisseria sp., diphlheroid, Staphylococcus aureus, Lactobacillus sp., Staphylococcus epidermidis, Bacillus suhtilis and Candida albicans. The saturated calcium hydroxide solution was effective against only four of the 11 microorganisms studied over a 60‐min exposure time. The calcium hydroxide solutions con‐taining detergent killed all 11 test organisms over a 30‐min exposure time. This difference was statistically significant (P<0.01).No statistically significant difference in antimicrobial action was found between the 10% and 20% detergent calcium hydroxide solutions (F>0.01). However, the low surface tension (46.5 × 10−3 Nm−1) and high pH (10.8) of the calcium hydroxide solution with 20% detergent establish it as the more effective solution.
Influence of age on the extent of voids in root canals sealed using a cold lateral condensation technique
Authors: MANOGUE M. , YOUNGSON C. C. , MARTIN D. M. 
Published: September 2007

SummaryThe aim of this study was to examine whether it is more difficult to achieve complete obturation of the root canal in teeth from different age groups, using the measurement of voids within the obturated canal to determine the quality of endodontic therapy. One‐hundred and fifty‐two single‐rooted premolar teeth extracted from patients of known age were collected. Following cleaning and storage the teeth were decoronated and radiographed. Forty selected teeth were allocated to one of four age‐groups, (under 20, 20–35, 36–50, over 50 years) each consisting of 10 teeth. The working length was determined radiographically and preparation was carried out using the step‐back technique. Each canal was obturated using cold lateral condensation with Tubliseal cement. The roots were then sectioned longitudinally and photographed. Sections and transparencies were subjected to image analysis to determine the total areas of root canal, sealer and voids respectively and statistical analysis of the differences between the various age groups was undertaken.There was a trend towards a reduction in the areas of sealer and sealer plus void with respect to increasing age group, although no significant differences existed. A significant relationship (P<0.05) was found between the area of voids found in the youngest group when compared with all other groups, the greatest cumulative area of voids being found in the youngest teeth.
In vitro efficiency of endodontic irrigation solutions on protein desorption
Authors: HAIKEL Y. , GORCE F. , ALLEMANN C. , VOEGEL J.‐C. 
Published: September 2007

SummaryThe use of irrigating solutions is widely accepted as a necessary adjunct to biomechanical preparation to obtain adequate cleansing of the root canal system.In this study, the efficiency of three solutions was tested in an in vitro experimental system for the removal of protein from apatite surfaces: Salvizol (a bis‐dequalinium acetate solution) and sodium hypochlorite at 0.5, 1, 3 and 6% at pH 7.4 and 11.5. Buffered Tris‐HCl solutions at pH 7.4 and 11.5 were used as controls.All chemicals showed rapid kinetic effects since no variation of the process could be detected after 5 min. Salvizol was the least efficient solution since it induced only a 2% protein desorption. Sodium hypochlorite efficiency increased with concentration to reach a 70% protein desorption from the apatite surface. In general, alkaline solutions were more efficient than buffered ones, and the ionic strength did not appear to have a major effect on the protein desorption process.
Effects of the Flexogates and Canal Master U on root canal configuration in simulated curved canals
Authors: CAMPS J. , MACOUIN G. , PERTOT W.‐J. 
Published: September 2007

SummaryThe purpose of this study was to compare the Canal Master U (CMU) instrumentation technique with that of a similar instrument, the Flexogates (FG).Forty simulated curved canals were divided in two groups of 20 each. One group was prepared using the CMU instrumentation technique and the other using the FG technique. Comparison was made by measuring the diameter of the prepared canals and transportation that occurred at the canal length and at levels 1, 3 and 5 mm coronal to the canal length. Data obtained were analysed statistically.Results showed that the final diameter of the prepared canals was not significantly different between the CMU or the FG. However, the FG transported the outer wall of the curvature more than the CMU at the canal length and at 1 mm from the CL. Although the difference in the canal transportation was statistically significant it may not be of clinical importance.
A laboratory study of root fillings in teeth obturated by lateral condensation of gutta‐percha or Thermafil obturators
Authors: DUMMER P. M. H. , LYLE L. , RAWLE J. , KENNEDY J. K. 
Published: September 2007

SummaryThe aim of this in vitro study was to assess the quality of root canal obturation and degree of apical dye penetration in teeth root‐filled with either laterally condensed cold gutta‐percha or Thermafil obturators. A total of 144 extracted teeth with single roots were included in the study. All canals were prepared with a standard technique using a sonic handpiece with copious irrigation. Radiographs taken of the teeth to show the maximum degree of canal curvature were then exposed and the angle, radius and position of curvature determined. This information about the canals, together with their working length and diameter at end‐point was used to divide the teeth into two experimental and two control groups. A total of 71 teeth were filled with Thermafil obturators, 69 with lateral condensation while four teeth remained unfilled and acted as controls. Following obturation, the teeth were radiographed in two planes and the technical quality of fill assessed on a four‐point scale. All access cavities were then sealed and the teeth immersed in dye for 48 h before being split longitudinally. Linear dye penetration via the apical foramen was then assessed. In both straight and curved canals obturation with Thermafil obturators was significantly quicker (P< 0.001) than lateral condensation. Apical extrusion of gutta‐percha occurred significantly more often in straight canals obturated with lateral condensation (P< 0.005) but there was no difference in curved canals. There was little difference in the radiographic quality of fill in the apical halves of the root fillings but Thermafil obturators were significantly better in the coronal halves when viewed from the proximal. Apical leakage of dye was significantly worse (P< 0.05) in curved canals filled with lateral condensation with a similar, but not significant, trend in straight canals. Under the conditions of this study, Thermafil obturators proved a satisfactor alternatie to lateral condensation of gutta‐perch.
An in‐vitro evaluation of the influence of temperature of plasticization on the sealing ability of Thermafil
Authors: LEUNG S. F. , GULABIVALA K. 
Published: September 2007

SummaryThe effect of temperature of plasticization on the sealing ability of Thermafil obturators was evaluated. Fortyeight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals had curvatures of less than 25 degrees, as determined using the Schneider technique. Four canals were used as positive and negative controls. All canals were prepared using a step‐back technique to size 30 at the working length. Roth's sealer was used in all canals. In one group the Thermafil obturators were thermoplasticized in an open flame, as recommended by the manufacturer. In the remaining three groups the obturators were thermoplasticized by immersion in water‐baths maintained at constant temperatures of 60, 75 and 90°C respectively. After immersion in Indian ink, the teeth were cleared and the depth of penetration of dye through the apical foramen was measured. In all specimens there was extrusion of sealer and sometimes gutta‐percha beyond the apical stop. Sometimes, there was leakage up to the apical stop but not beyond. In view of this the measurements were divided into leakage from the apical foramen to the apical stop and from the apical stop coronally. It was found that in the zone between the apical foramen and the apical stop the Thermafil obturators plasticized at 60°C produced a signficantly better seal than those obturators plasticized in an open flame (P<0.05). In the zone coronal to the apical stop there were no significant differences in leakage between the groups.
Clinical reliability of the dentine bridge formed after pulpotomy: A case report
Authors: çALISKAN M. K. 
Published: September 2007

SummaryAn exposed pulp in a crown‐fractured vital young tooth may be treated with either pulp capping or pulpotomy, using a calcium hydroxide dressing. Calcium hydroxide stimulates dentine bridge formation, which is a good indicator of pulp vitality.In this case it is reported that, although seriously contaminated for a long period with debris from the oral environment, the dentine bridge which formed after pulpotomy was able to function as a protective pulpal barrier. The tooth responded to an electrical pulp tester within normal limits and the periapical radiographic appearance was normal at review after 7 years.
Retreatment or radiographic monitoring in endodontics
Authors: VAN NIEUWENHUYSEN J.‐P. , AOUAR M. , D'HOORE W. 
Published: September 2007

SummaryThe aim of this clinical study was to assess 1032 endodontically treated roots in relation to: (i) the success rate of retreatment (612 roots)—only cases that had recall examinations of 6 months or longer were evaluated; (ii) the influence of various factors on the technical and clinical results of the retreatment; and (iii) the consequences of radiographic monitoring of 420 asymptomatic roots when the root filling was radiographically deficient (short, overextended and/or permeable root fillings).Technical assessment of the retreatment showed that the root was adequately sealed in 52.3% of cases, the root filling was improved in 33.8%, was identical with the initial treatment in 11.1% and was worse than the first treatment in 2.8% of the canals. Clinical assessment of the retreatment of symptomatic roots showed that 71.8% of the retreatments were judged successful, 18.9% showed some healing and 9.3% had failed. The initial size of the periapical lesion, the use of rubber dam, the root filling technique and the apical level of the root filling had a statistically significant influence on the result of the retreatment.Monitoring radiographically (median time span 6 years) led to maintenance of the status quo in 94.8% of cases, healing in 2.4% and failure in 2.8% of the canals. Retreatment is clearly indicated when periapical radiolucency, clinical signs and/or symptoms are present with relative success of up to 91%. When no or little radiographic evidence of periapical pathology was present, when clinical signs and symptoms were absent or when the root filing was radiographically deficient, radiographic monitoring led to complications in only a limited number of cases.