bluuebunny/crossref_metadata_2025_split huggingface dataset:
The cumulative effect of disinfection, storage, histological fixation and demineralization on number and staining ability of Gram‐positive bacteria
Authors: WIJNBERGEN M. , VAN MULLEM P. J. 
Published: September 2007

SummaryIt has previously been shown experimentally using S.faecalis that the relative number of blue‐staining Gram‐positive bacteria was reduced by demineralizing agents as well as by disinfection (Wijnbergen & van Muilera 1987, van Mullem & Wijnbergen 1989). In this study the cumulative effect of disinfection, experimental period, fixation and demineralization was investigated. The use of additives to the fixative and the demineralizing agents to limit the toss of bluestaining bacteria was also studied. The numbers of bacteria were determined using a haemocytometer, and the percentage of blue‐staining organisms were ascertained from smears.When compared with the start of the experiment, the sequence of disinfection with chlorhexidine, storage in PBS, fixation with neutral formaldehyde and demineralization with formic acid or EDTA appeared to reduce the relative numbers of Gram‐positive staining bacteria. For storage periods of 0 and 4 days the reduction factors were 100 and 600, respectively, using formic acid. These factors were 50 and 95, respectively, using EDTA. Addition of cetyl pyridinium chloride to the fixative and the demineralizing agents, and addition of neutral formaldehyde to the demineralizing agents lowered these reduction factors to 80 and 200, respectively, for formic acid, and 40 and 85, respectively, for EDTA.If the results are extrapolated to animal experiments where disinfection, experimental period, fixation and demineralization form part of the experimental framework, even the lowest reduction in the number of blue‐staining bacteria could lead to false interpretation of tissue sections.
Comparison of six files to prepare simulated root canals. Part 1
Authors: AL‐OMARI M. A. O. , DUMMER P. M. H. , NEWCOMBE R. G. 
Published: September 2007

SummaryA total of 300 simulated root canals of various angles and positions of curvature in clear resin blocks were prepared by hand using either K‐files, K‐Flex files, Flexo‐files, Flex‐R files, Hedstrom files or Unifiles. Each fife type was used to prepare 50 canals employing a linear filing motion and an anticurvature stepback technique. Part 1 of this two‐part report describes the efficacy of the files in terms of preparation time, instrument failure, loss of canal length and weight loss from the blocks. Two‐way analysis of variance confirmed that there was significant variation for each parameter between instruments, between canal types, and with interaction between instruments and canal types. Overall, preparation with Hedstrom files was significantly quicker than with any other file, whilst preparation with K‐files and K‐Flex files took significantly longer. Fracture and deformation of instruments occurred substantially less often with Flex‐R and Hedstrom files, but significantly more often with Unifiles. Loss of working distance occurred with all file types, but was significantly greater in canals prepared with K‐files. Unifiles and Hedstrom files were responsible for significantly more weight toss than the other files, whilst K‐files produced significantly less weight loss. Canals with rough undulating walls were created most often by Hedstrom files and Unifiles. Overall, under the conditions of this study, Flexofiles, Flex‐R files and Hedstrom files appeared to be substantially more effective than K‐files, K‐Flex files and Unifiles.
Comparison of six files to prepare simulated root canals. Part 2
Authors: AL‐OMARI M. A. O. , DUMMER P. M. H. , NEWCOMBE R. G. , DOLLER R. , HARTLES F. 
Published: September 2007

SummaryA total of 300 simulated root canals of various angles and positions of curvature in clear resin blocks were prepared by hand using either K‐files, K‐Flex files, Flexo‐files, Flex‐R files, Hedstrom files or Unifiles. Each file type was used to prepare 50 canals employing a linear filing motion and an anticurvature stepback technique. Part 2 of this two‐part report describes the efficacy of the files in terms of the prevalence of canal aberrations, the amount and direction of canal transportation and the overall postoperative canal shape. Hourglass shaped canals were found in 4.5% of curved canals, the majority of these being created by K‐files and K‐Flex files. Perforations were seen in 6.3% of curved canals, the majority being produced by Flex‐R files and K‐files. Excessive removal of material from along the inner aspect of the canal curve occurred in 10.4% of canals, by for the majority being created by Hedstrom files. Transportation of canals was a consistent finding with all instruments. Two‐way analysis of variance revealed how significant differences in the absolute magnitude of transportation occurred between instruments, between canal types and by an interaction between instrument and canal type. In general, transportation was towards the outer aspect of the canal curve at the end‐point of preparation and the zip and elbow, but towards the inner aspect at the beginning of the curve. Further towards the orifice, transportation reverted to the outer aspect of the canal curve. In straight canals, one‐way analysis of variance indicated that significant differences (P < 0.05) occurred in the width of canals at their end‐point between instruments. In curved canals, two‐way analysis of variance indicated that the width of canals throughout their length varied significantly between instruments, between canal types and in some instances with interaction between instrument and canal type. Under the conditions of this study.
Variables affecting electronic root canal measurement
Authors: WU Y.N. , SHI J. N. , HUANG L. Z. , XU Y. Y. 
Published: September 2007

SummaryThis study was conducted in two parts. In the first part, 20 single‐rooted teeth that had been scheduled for extraction were investigated. The electronic root canal lengths were measured in vivo with a Dental Sono‐Explorer type Y‐III, and the actual canal lengths were measured after extraction of the teeth. The rate of agreement of the two measurements was 77.5% within a range of ±0.5 mm, while it was 100% at ±2.0mm, which is acceptable clinically. In the second part, there were 19 simulated canals whose lengths and apical foramen sizes were known beforehand. Experiments revealed a negative correlation between the areas of the apical foramina and the difference between the electronic and the actual root canal lengths. This relationship was shown by the linear regression equation:ŷ= 0.6 − 1.6x.With the exception of the smallest areas of foramina, electronic root canal length measurements were less than the actual lengths.
A method for experimental dental radiography
Authors: FORSBERG J. 
Published: September 2007

SummaryAn apparatus was designed for experimental dental radiography, which permitted separate adjustment of the subject, target and film. The precision of the apparatus was tested by radiographing a test subject, consisting of small steel globes embedded in a plastic plate. The subject was placed in the apparatus and exposed 30 times on dental X‐ray film with different adjustments of angles and distances. All exposures were repeated after readjustment of the same form. Three linear distances between pairs of the projected steel globes were selected and measured on each radiograph. Depending on the different orientations of film, target and subject, the distances measured ranged from 9.0–11.1 mm, from 7.0–10.7 mm and from 12.7–17.3 mm, respectively. From the measurements on the radiographs the error of method was calculated to be 0.07–0.08 mm and the error of measurement to be 0.05–0.06 mm. The precision of the apparatus was thus found to be adequate for measurement of differences in small, but clinically relevant, distances.
Diagnostic dilemma: an unusual presentation of an infected nasopalatine duct cyst
Authors: GULABIVALA K. , BRIGGS P. F. A. 
Published: September 2007

SummaryThe pertinent literature on nasopalatine duct cysts is reviewed. A case is reported in which a nasopalatine duct cyst infected by Actinomyces presented clinically with unusual features. The clinical findings could have been confused with an early acute periapical abscess arising from an incisor tooth. The relevant aspects of diagnosis are discussed.
Quantitative radioactive analysis of microleakage of four different retrograde fillings
Authors: DANIN J. , LINDER L. , SUND M.‐L. , STRÖMBERG T. , TORSTENSON B. , ZETTERQVIST L. 
Published: September 2007

SummarySealing properties of four different retrograde filling materials were investigated in vitro. Radioactive isotopes were applied in the root canal, and leakage into an extraradicular fluid was measured at regular intervals. The method permitted repeated observation of the specimens over prolonged periods of time. Forty single‐rooted human teeth were biomechanically instrumented and obturated using calcium‐hydroxide paste. Following obturation, an apicectomy was performed and retrograde cavities were filled with four different materials: group 1, non γ2. amalgam (Amalcap): group 2, glass ionomer cement (Ketac Silver); group 3, calcium‐hydroxide‐based root canal sealer (Sealapex); group 4, composite resin (Palfique Light‐S). After removal of the calcium hydroxide, the teeth were immersed in a fluid. An isotope solution was then placed in the root canals. Samples were taken from the fluid at 0, 3, 7, 28, 56, 105, 210, 285 and 376 days to determine the radioactivity. It was found that Sealapex and Palfique Light‐S showed significantly less leakage than amalgam and glass ionomer cement, which had the highest apical leakage.
Systemic release of corticosteroids following intra‐dental use
Authors: ABBOTT P. V. 
Published: September 2007

SummaryConcern has been expressed in the past that the use of corticosteroids within root canal medicaments or pulp capping agents may lead to deleterious systemic effects. Calculations of the highest possible amounts that could be used, plus an analysis of the release and diffusion characteristics, and comparisons with known endogenous levels of corticosteroids, reveal that the intra‐dental use of Ledemnix paste and Ledermix cement is unlikely to result in any systemic side‐effects.
Tissue responses to Hydron, assessed by intraosseou simplantation
Authors: REID R. J. , WILSON D. F. , CHAU K. K. , HEITHERSAY G. S. , HEIJKOOP P. S. 
Published: September 2007

SummaryTeflon tubes containing freshly mixed, polymerized Hydron root canal filling material, folly set AH26 or Teflon were implanted into the mandible of guinea pigs andassessedhiilogically at 2 days. l,2,4,12 and 26 weeks. None of the materials tested elicited signs of overt or significant tissue damage, and polymerized Hydron was assessd to be as biocompatible as folly set AH26 and Teflon. Bone formed in very close apposition to the polymerized Hydron. whereas a soft tissue capsule separated the regenerated bone loom implants of AH26 and Teflon.
A comparison of leakage of filling materials in demineralized and non‐demineralized resected root ends under vacuum and non‐vacuum conditions
Authors: PETERS L. B. , HARRISON J. W. 
Published: September 2007

SummaryA study was conducted to compare the marginal apical leakage of root‐end filling materials under vacuum and non‐vacuum conditions, and to assess the effect of demineralization by application of citric acid to the root ends on the apical marginal leakage of root end filling materials. The root canals of 148 extracted human canines and premolars were handfiled and sealed with gutta‐percha and Roth's 801 sealer using cold lateral condensation. The teeth were divided into 8 groups that received retrofilling materials. The materials tested were amalgam, IRM and gutta‐percha/sealer with and without successive application of citric acid. Half of the specimens were placed under vacuum conditions in methylene blue dye, and the other half were placed in the dye for the same time period without exhausting air from the flask. The teeth were split longitudinally and the extent of dye penetration was determined with a stereomicroscope and eyepiece micrometer. The most evident difference in dye penetration was found between the positive control groups. Under vacuum conditions, the positive controls showed complete penetration of the unobturated canal system with dye. With passive immersion only partial penetration of the unobturated canal system occurred. Application of citric acid to the root end did not adversely affect the seal of amalgam, IRM or gutta‐percha/sealer.
Clinical detection of the minor mesiobuccal canal of maxillary first molars
Authors: TING P. C. S. , NGA L. 
Published: September 2007

SummaryOne hundred extracted maxillary first molars from a South East Asian population were sectioned at a level below the roof of the pulp chamber. The detection of the minor mesiobuccal canal was determined on the pulpal floor using a size 08 file. When the canal was not detected by this technique, its presence or absence was then determined by sectioning the mesiobuccal root transversely, and the position of the extra canal was explored from the cut end. It was found that by modifying the outline of the access cavity, and by widening and deepening the groove running palatally from the major mesiobuccal canal up to a depth of 0.5 mm and a distance of 2.0 mm, the visibility of the extra mesiobuccal canal orifice was greatly improved. This study showed that more than 50% of maxillary first molars had a minor mesiobuccal canal, and 19% of these canals could not be detected clinically.
Periradicular healing and apical closure of a non‐vital tooth in the presence of bacterial contamination
Authors: GUTMANN J. L. , FAVA L. R. G. 
Published: September 2007

SummaryThis case report addresses the periradicular tissue response and root‐end closure of a maxillary central incisor in the presence of bacterial contamination. The implications for the control of bacteria through the use of calcium hydroxide and/or systemic antibiotic coverage are considered in the light of scientific evidence and clinical treatment.
Failure characteristics of endodontically treated premolars restored with a post and direct restorative material
Authors: HUYSMANS M.‐C. D. N. J. M. , PETERS M. C. R. B. , PLASSCHAERT A. J. M. , VAN DER VARST P. G. T. 
Published: September 2007

SummaryNinety‐one extracted maxillary premolar teeth were restored with a prefabricated post and amalgam, composite resin or glass‐cermet core. Each group was again divided into three groups of 9–13 teeth to be subjected to an increasing load in one of three standardized directions (10, 45 and 90° to the long axis of the tooth). Failure load and characteristics of failure were recorded. The glass‐cermet‐restored teeth had a lower strength than the other groups for every load direction (Student's t‐test: P < 0.01). Amalgam and composite resin groups showed a significant difference only for the 10% loading condition (Student's test: P < 0.02). Teeth restored with amalgam cores displayed a higher mean failure load, in combination with a 46% occurrence of root fracture.
Root Fractures in permanent teeth: a clinical review
Authors: YATES J. A. 
Published: September 2007

SummaryA retrospective study of 22 root fractures in 21 patients was performed. Ten patients were less than 11 years of age, and boys were involved more often than girls. Ten patients had more than one injured tooth, but there was no case of alveolar fracture. Twenty‐one of the teeth were upper central incisors. Only 11 teeth were seen within the first week, so that not all teeth were splinted and not all displaced teeth were repositioned. Long‐term clinical and radiographic review showed that loss of vitality of the coronal pulp could not be reliably detected for at least 1 year. No tooth became abscessed or developed a sinus tract, and resorption of bone at the fracture line was observed in only one out of five non‐vital teeth. Lack of displacement and placing of a splint increased the chances of the pulp remaining vital and healing of the fracture occurring with hard tissue. Sclerosis of the coronal pulp occurred mainly when healing was by connective tissue. The apical pulp always remained vital, and there was sclerosis of the apical pulp in almost every case.
Asymmetry of the root canal foramen
Authors: BLAŠKOVIČ‐ŠUBAT V. , MARIČIČ B. , ŠUTALO J. 
Published: September 2007

SummaryDeviation of the major apical foramen from the anatomical root apex is a recognized phenomenon. To determine the frequency, position and mean distance of the major apical foramen from the anatomical root apex, 230 roots of permanent teeth were examined stereo‐microscopically and radiographically. Radiographic analysis was used to establish how accurate the conventional radiograph was in displaying such a deviation.The frequency of deviation of the major foramen, determined stereomicroscopically, was 76%, and depended on the type of teeth examined. Radiographic analysis of the same sample revealed 57% of root canals had asymmetry of the root canal foramen. Agreement of stereomicroscopic and radiographic findings was found to be 61%. The most frequent deviation of the major foramen was on the distal root surface (29%), but this was not statistically significant. The mean distance between the deviation of the major foramen and the anatomical root apex was 0.99 mm. The study indicates that the clinician should consider deviation of the foramen during root canal treatment, as the deviation could not easily be detected radiographically.
A survey of endodontic procedures performed by practitioners in limited practice
Authors: HARTY F. J. 
Published: September 2007

SummaryPatients are sometimes referred for treatment to dentists who limit their practices to endodontics. A survey of consecutive referrals to seven such dentists was undertaken. The most common reasons for such referrals were (i) for the retreatment of a tooth with a previous root filling, (ii) because the referring dentist was unable to control pain and/or swelling, or (iii) because the referring dentist was unable to diagnose the endodontic problem. Only 60 (12.8%) of the 469 reasons reviewed were in teeth that were symptomless, uncomplicated and untouched by the referring dentist.
The use of glass ionomer as a root canal sealer—a pilot study
Authors: SAUNDERS W. P. , SAUNDERS E. M. , HERD D. , STEPHENS E. 
Published: September 2007

SummaryThe use of a resin‐based glass ionomer as an endodontic sealer was studied in vitro. The root canals of extracted single‐rooted human teeth with mature apices were prepared using a stepback technique. Subsequently, the smear layer was removed with 40% citric acid and the canals obturated using lateral condensation of cold gutta‐percha and a resin‐based glass ionomer as the sealer. The relationship between the sealer and the wall of the root canal was studied using scanning electron microscopy. The shear bond strength of gutta‐percha to this glass ionomer was also determined. Finally, the uptake of fluoride into the wall of the root canal was studied using scanning electron microprobe analysis after storage for 2 weeks, 1 month and 3 months following root filling with gutta‐percha and glass ionomer cement. The results showed that removal of the smear layer allowed the sealer to enter some of the dentinal tubules. This was observed most frequently in the middle third of the root canal, where there was good adaptation of the sealer. The shear bond strength of gutta‐percha to the glass ionomer sealer was not significantly different from that obtained between gutta‐percha and a proprietary zinc oxide‐eugenol endodontic sealer. The concentration of fluoride in the dentine in the coronal part of the root canal increased after obturation with gutta‐percha and the glass ionomer sealer at every time interval. The increase in fluoride concentration varied widely between teeth. It is concluded that a resin‐based glass ionomer cement may have potential as a root canal sealer.
The effect of smear layer upon the coronal leakage of gutta‐percha root fillings and a glass ionomer sealer
Authors: SAUNDERS W. P. , SAUNDERS E. M. 
Published: September 2007

SummaryThe effect of the removal of the smear layer on coronal leakage of root fillings was studied using two sealer cements. Sixty single‐rooted teeth with mature apices were prepared chemomechanically using a modified double‐flared technique with non‐cutting tipped files and copious irrigation with 2% sodium hypochlorite. The teeth were randomly allocated to four groups of 15 teeth each. Two groups were treated with 40% citric acid to remove the smear layer. Two groups of teeth, one with and one without smear layer, were filled by lateral condensation of gutta‐percha with either Tubliseal or a resin‐based glass ionomer, Vitrebond. The teeth were stored for 1 week, thermocycled, and the extent of coronal leakage determined for each group after immersion in Indian ink for 90 h. The teeth were demineralized, dehydrated and immersed in methyl salicylate which rendered them transparent. Linear measurement of dye penetration was recorded. The mean depth (± SD) of leakage for the groups in which the smear layer was left intact was 4.26 ±1.53 mm and 6.83 ± 1.65 mm for the Vitrebond and Tubliseal, respectively. When the smear layer had been removed, the mean depth of leakage for the Vitrebond group was 1.13 ±0.29 mm, and 3.72 ± 1.23 mm for the Tubliseal group. There was a statistically significant difference in leakage between the groups (P > 0.001). With both sealers, those teeth in which the smear layer had been removed showed less leakage than the specimens in which the smear layer was left intact (P > 0.001). The Vitrebond specimens leaked less than the teeth that were root filled using Tubliseal, both when the smear layer was intact and when it was absent (P > 0.001).
The apical seal of root canal sealing cements using a radionuclide detection technique
Authors: CANALDA‐SAHLI C. , BRAU‐AGUADE E. , SENTIS‐VILALTA J. , AGUADE‐BRUIX† S. 
Published: September 2007

SummaryThe aim of this study was to evaluate the apical seal obtained with various root canal sealing cements using a new method based on the use of a radionuclide and an external detection technique. A total of 150 maxillary incisors and canines, which had been kept in saline solution, were used. The root canals were instrumented with a stepback technique and circumferential filing. Six experimental groups and two control groups were randomly formed. Each experimental group was obturated by a lateral condensation technique with gutta‐percha points and a different seating cement (two based on zinc oxide‐eugenol cement, two based on resins and two on calcium hydroxide); the positive control used gutta‐percha without sealing cement, while in the negative control the apex was covered with nail varnish, leaving the root canal empty. The apical leakage was measured using an external detection technique after submerging the root apices in a solution containing the radioisotope metastable 99Tc. No leakage was observed in the negative control group. There was a large difference between the leakage observed in the positive control group and the experimental groups. The best seal was obtained using Sealapex cement, which dif‐feredsignificantly from AH26, Tubli‐Seal and Diaket; there was no significant difference between the latter. The poorest results were obtained with Endomethasone and CRCS; there was a significant difference between these and the previous three sealing cements.
Human pulpectomy: incidence of postoperative pain using two different intracanal dressings
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 pulpectomy and dressing with a corticosteroid‐antibiotic preparation or a calcium‐hydroxide paste. Sixty teeth from 45 patients were prepared and dressed on the first visit and re‐evaluated 7 days later. No difference was observed in the incidence of postoperative pain between the two groups.