bluuebunny/crossref_metadata_2025 huggingface dataset:
The presence of nerve fibres in the coronal odontoblast layer of teeth at various stages of root development
Authors: PECKHAM K. , TORABINEJAD M. , PECKHAM N.
Published: September 2007

Summary. Many studies have investigated the presence of nerve fibres in the coronal odontoblast layer of mature teeth. However, little information is available on the presence of these structures in immature human teeth. The pulps of 18 human maxillary and mandibular third molars at various stages of development were collected, sectioned, and stained by the immunoperoxidase technique. The results showed the presence of numerous myelinated nerve fibres in the coronal odontoblast layer of teeth with fully formed roots. Similar observations were made in teeth with half formed roots, and in those without roots. On the basis of these results, it appears that a lack of response to vitality tests in teeth with incompletely formed roots is not wholly due to the absence of nerve fibres in the coronal odontoblast layer.
The effect of post space preparation on the apical seal of root fillings using chemically adhesive materials
Authors: SAUNDERS E. M. , SAUNDERS W. P. , RASHID M. Y. A.
Published: September 2007

Summary. The effect on the apical seal of root filling teeth with two sealer cements that reacted chemically with tooth structure was studied in vitro. In addition, apical leakage of teeth obturated with these materials and subsequently prepared to accept a post was tested. Ninety single‐rooted teeth with mature apices were prepared chemomechanically by the stepback technique using files and copious irrigation with 2.5 per cent sodium hypochlorite. The teeth were then randomly allocated to six groups of 15 teeth each. Two groups were root filled by lateral condensation of gutta‐percha and one of three sealer cements: Tubliseal, a radiopaque glass ionomer luting cement, Ketac Cem, and a chemically active composite resin, Panavia Ex. Thirty minutes later, in one group for each material, a post space was prepared leaving 4–5 nun of root filling at the apex. The extent of apical leakage in each group was determined after immersion in Indian ink for 14 days. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent, and a linear measurement of dye penetration was recorded.

No statistically significant difference in the extent of leakage was found between the sealers in those groups which were filled by lateral condensation and left intact. However, the degree of leakage increased after post space preparation with the glass ionomer and Tubliseal groups, but was reduced in the Panavia Ex group.
Effects of extensive apical reaming and calcium hydroxide dressing on bacterial infection during treatment of apical periodontitis: a pilot study
Authors: ØRSTAVIK D. , KEREKES K. , MOLVEN O.
Published: September 2007

Summary. An apical dentine sampling technique was applied in order to monitor the bacteriology of the pulp canal and radicular dentine before and during treatment of teeth with chronic apical periodondtis. Twenty‐three teeth with a radiographic diagnosis of apical periodontitis were studied. They were subjected to a standardized two‐appointment treatment regimen of extensive apical reaming in the absence of antimicrobial agents and 1‐week dressing with calcium hydroxide. Bacteriological samples were taken from the root canal at the start, and apical dentine samples at the end, of each sitting. Provision was made to allow growth of anaerobic bacteria. All root canals but one showed growth at the start of treatment. Dentine samples were positive in 14 of the 23 teeth at the end of the first appointment. Eight of the 23 canals had detectable growth from the canal at the start of the second appointment, but in sufficient numbers for quantification in only one root canal. The subsequent dentine sampies were otherwise negative at the second appointment. There was a tendency for teeth causing symptoms to harbour more bacteria than symptomless teeth.
Class II antigen expressing cells in experimentally induced pulpitis
Authors: BERGENHOLTZ G. , NAGAOKA S. , JONTELL M.
Published: September 2007

Summary. This study reports on the occurrence of class II antigen expressing cells in inflammatory lesions experimentally induced in the rat incisor pulp. Concanavalin A and lipopolysaccharide of Bacteroides gingivalis were applied to the exposed pulp following a preparation through alveolar bone and dental tissues in the midpart of the root. In a set of control teeth, pulpal exposures were capped with Cavit without the placement of antigenic material. Animals were killed after 3, 12, 24, 48 or 96 hours. Pulp tissue specimens were subjected to immunohistochemical analysis utilizing a monoclonal mouse anti‐rat class II antigen antibody. Semi‐quantitative assessment of positively stained ceils was carried out under the light microscope. Significantly more class II antigen expressing cells were identified in the challenged pulps than in the controls at all experimental periods. The increase in cells peaked at 48 hours to taper off at the subsequent 96‐hour observation. The rapid and intense influx of class II antigen expressing cells suggests that these cells are associated with the initial defence of the dental pulp.
Self‐replantation of an avulsed tooth: 30‐year follow‐up
Authors: ABBOTT P. V.
Published: September 2007

Summary. A 42‐year‐old man had been previously hit in the mouth when he was 12 years old, and the upper left central incisor was completely avulsed. The patient immediately replanted the tooth and did not seek any dental treatment. After 28 years he noticed discoloration and abscess formation. Root canal treatment was performed, and the tooth has remained in a stable, functional position.
The adaptation and sealing ability of light‐cured glass ionomer retrograde root fillings
Authors: CHONG B. S. , FORD T. R. PITT , WATSON T. F.
Published: September 2007

The adaptation and sealing ability of a light‐cured glass ionomer cement when used as a retrograde root filling was assessed using a confocal optical microscope with and without a fluorescent dye. This material was compared with a conventional glass ionomer cement and amalgam. The root canals of 60 extracted human single‐rooted teeth were prepared and filled with gutta‐percha and sealer. All the teeth were apicected, retrograde cavities were prepared, and then divided into three groups of 20 teeth each and filled with the test materials. The light‐cured glass ionomer cement was well adapted to the retrograde cavity and apicected root surface. Within the retrograde cavity the cement was often well adapted to one wall, but gaps were found on the opposite cavity wall. This was probably caused by the polymerization contraction of the material. In contrast, the amalgam retrograde root fillings were poorly adapted to the cavines, with gaps between the cavity walls and amalgam. This group exhibited the poorest sealing ability as measured by the extent of dye penetration. The conventional glass ionomer cement was often found smeared over the root face, and there were unfilled voids at the base of some retrograde cavities. The results of the dye leakage study were analysed statistically The sealing ability of the light‐cured glass ionomer cement was significantly better than that of amalgam (P < 0.001). The dye penetration around the light‐cured glass ionomer cement and the conventional glass ionomer cement was not significantly different (P > 0.05). However, the sealing ability of the conventional glass ionomer cement was significantly better than that of amalgam (P < 0.05).
Toxicity of Pulpispad using four different cell types
Authors: PISSIOTIS E. , SPÅNGBERG L. S. W.
Published: September 2007

The cytotoxic effect of a zinc oxide‐eugenol‐based paste (Pulpispad) was evaluated in vitro after setting for 1 day and 1 week. Target cells were L929 cells, gingival, periodontal ligament and pulpal fibroblasts. The material was incubated with the cells for 4 and 24 hours, and its toxicity was evaluated with the 51Cr‐release method. Puipispad was highly cytotoxic to all cell lines even after setting for 1 week. The use of Pulpispad is not recommended for future clinical application. The various responses among the four cell lines indicated that diploid cell lines can, under certain circumstances, be less sensitive than aneuploid cell lines. It is therefore suggested that in the evaluation of biomaterials the choice of cell lines should be carefully considered, as they can display varying sensitivities.
One‐appointment root canal treatment: incidence of postoperative pain using a modified double‐flared technique
Authors: FAVA L. R. G.
Published: September 2007

A clinical study of maxillary central incisors was conducted in order to evaluate the incidence of postoperative pain following one‐appointment root canal treatment using a modification of the double‐flared technique to prepare the root canal system. Sixty teeth with necrotic pulps, from 52 patients whose ages ranged from 10 to 53 years, were inciuded. Half of the teeth were prepared by the double‐flared technique, while the other half were prepared by a modification of this technique. No difference was observed in the incidence of postoperative pain between the two groups.
Blood flow changes in the dental pulp during limited exercise measured by laser Doppler flowmetry
Authors: WATSON A. D. M. , PITTFORD T. R. , McDONALD F.
Published: September 2007

The effect of limited exercise on pulpal blood flow was assessed by laser Doppler flowmetry (LDF). The primary aim of the investigation was to determine whether clinically significant changes could be induced by mild exercise when LDF was used to monitor pulpal blood flow.

Blood flow readings were obtained from the coronal pulps of 17 upper central incisor teeth of 10 human volunteers before, during and after limited exercise. Readings were also obtained from the adjacent attached gingivae. Pulse rate was recorded concurrently. Pulpal Mood flow was found to vary during exercise, with a mean percentage change of 38% from the level at rest; the range was from a 100% decrease to a 2 00% increase. The mean percentage increase in gingival blood flow was 65%, with a range of 6–300%. The main indication that blood flow was being assessed was the pulsatile nature of the output. Results were compared only within individual teeth. The pulse rate increased during exercise (mean percentage increase 54%, range 11–98%). There was no direct relationship between increased pulse rate and pulpal Mood flow. It was evident that the mechanisms controlling pulpal and gingival blood flows differed.

Laser Doppler flowmetry readings were only repro‐ducible in individual teeth provided that the patient was at rest, and this should be taken into account in clinical or research measurements.
The role of intracanal medication in root canal treatment
Authors: CHONG B. S. , FORD T. R. PITT
Published: September 2007

The role of intracanal medication as a root canal dressing is re‐examined. In pulpectomy and some root canal treatments, where the root canal contains vital pulp tissue, it is doubtful whether a routine intracanal medicament is needed.

In infected root canals, intracanal medication has been advocated for many purposes. An intracanal medicament is used to:

(i) eliminate any remaining bacteria after canal instrumentation;

(ii) reduce inflammation of periapical tissues and pulp remnants;

(iii) render canal contents inert and neutralize tissue debris;

(iv) act as a barrier against leakage from the temporary filling;

(v) help to dry persistently wet canals.

However, most of the indications for intracanal medicaments are questionable.

Intracanal medicaments should only be used for root canal disinfection as part of controlled asepsis in infected root canals, and their role is secondary to cleaning and shaping of the root canal. Thorough canal debridement and adequate canal preparation are more pertinent, and their importance is emphasized. Bacteriological sampling may be necessary if a tooth does not respond to treatment, to help in the choice of intracanal medicament.
Cell responses to Hydron by a new in‐vitro method
Authors: MCNAMARA J. R. , HEITHERSAY G. S. , WIEBKIN O. W.
Published: September 2007

An in‐vitro biotoxicity test system, suitable for the assessment of endodontic filling materials, has been developed and used to test cell responses to Hydron, AH26 and Tubliseal. A robust, well‐characterized and stable cell line (L‐cells) which was grown as uniform cultures on Miliipore filters, has been used as indicator cells. As they approached confluence they were exposed to test substances for 24 h and biosynthetic activities were measured. The test system is a modification of that described by Wennberg et al. (1979). By inverting the cultures on organ‐culture rafts, cells were separated from the test material, which was placed on top of the Miliipore filters. Freshly mixed polymerizing Hydron and prepolymerized Hydron were tested. The cell responses were compared with those of cultures exposed to freshly mixed AH26 and Tubliseal. Polymerizing and prepolymerized Hydron depressed both cell division, assessed by 3H‐thymidine incorporation, and the synthesis and secretion of matrix material as measured by precipitable 35S‐sulphate. Prepolymerized Hydron decreased cell functions by 59% and 56% of live cell controls, respectively, while the freshly mixed polymerizing Hydron inhibited biosynthesis by 89% and 94%, respectively. The data for polymerizing Hydron were compared with results for other root‐filling materials and showed similar values to those for Tubliseal (92% and 95%), but greater inhibition of biosynthesis than for AH26 (53% and 50%). The AH26 values were similar to those obtained from cultures exposed to the prepolymerized Hydron. Recovery of biosynthetic capacity by these cultures after removal of all endodontic material was also assessed. Partial biosynthetic recovery of cell cultures was observed 24 h after removal of prepolymerized Hydron. The unpolymerized Hydron continued to yield a soluble component which substantially depressed biosynthetic activity of the experimental cultures up to 14 days. In general, the results indicated that Hydron, particularly in its freshly mixed state, when not in actual cell contact, depressed cell division and extracellular‐matrix synthesis. Data derived from similar in‐vitro testing with AH26 and Tubliseal revealed that they both inhibited cell division and matrix synthesis. Tubliseal inhibited these cell responses to the same extent as polymerizing Hydron. Polymerizing Hydron was significantly more toxic than AH26, while there were no significant differences in the levels of toxicity of polymerized Hydron and AH26.
Comparison of three imaging techniques for assessing endodontic working length
Authors: GRIFFITHS B. M. , BROWN J. E. , HYATT A. T. , LINNEY A. D.
Published: September 2007

The accuracy of endodontic working length estimation was investigated using three imaging techniques: radiography (Rd), Xeroradiography (Xr) and Radiovisiogra‐phy (RVG positive and negative prints). An in‐vitro model of extracted single straight roots, mounted in wooden blocks with wax, was employed in the study. Optimum exposures were established for each of the imaging techniques. The magnification of the images was measured and the resolution of the RVG images was also investigated. Comparable Rd (D‐speed film). Xr, RVG positive and RVG negative images were made of five roots with size 10 files in situ. Images of 10 standard files were made, ranging from 2.0 nun through the root apex to 2.5 mm short of the apex, resulting in 200 images. Six observers each assessed the working distance on 100 images, measuring the distance from the apical foramen to the file tip. After allowing for the magnification of the images, these results were compared with the‘true’file tip to apical foramen (measured with the aid of a reflex microscope). The inaccuracy of working distance estimations was considered to be of clinical significance (> 0.5 mm) in 6% of measurements made from Rd and Xr, 19.2% of measurements from RVG negative and 32.3% from RVG positive images. In addition, 14% of RVG images were too poorly defined to be assessed. The first‐generation RVG system was used in this study. It was therefore concluded that the most accurate estimates of working distance were made from Xr and Rd images, and that RVG images, particularly the RVG positive images, were the least accurate and most difficult to read. In comparison with radiographs using D‐speed film, a reduction in radiation exposure of 10% was made for Xr and of 60% for RVG. This was considered to be of clinical significance, and would be particularly important if the resolution of the RVG prints were to be improved by further development of the RVG system.
Scanning electron microscopic study of the apical dentine surfaces lased with Nd: YAG laser following apicectomy and retrofill
Authors: STABHOLZ A. , KHAYAT A. , WEEKS D. A. , NEEV J. , TORABINEJAD M.
Published: September 2007

The purpose of this investigation was to study the effects of a Nd:YAG laser on the5 cut surface of teeth using scanning electron microscopy (SEM). Eighteen single‐rooted teeth were cleaned, shaped, and obturated with gutta‐percha and root canal sealer. The apical 3 mm of each tooth were resected with a diamond fissure bur, and the teeth were randomly divided into two groups of nine teeth each. The resected surface of each root in one group was lased twice. The duration of lasing and the number of pulses were recorded for each tooth. The teeth were air dried, mounted on stubs, sputter‐coated with gold‐palladium and examined under SEM. Application of the Nd:YAG laser caused melting of apical dentine surfaces. The melted material resembled the appearance of glazed interconnected droplets. Resolidification and recrystal‐ization of the melted areas appeared to be incomplete and discontinuous. Some areas between the glazed regions appeared similar to those of non‐lased apical dentine resected root surfaces.
A comparison in vitro of two ultrasonic root canal preparation techniques
Authors: YAP S.Y.S. , STOCK C. J. R.
Published: September 2007

Two ultrasonic techniques were compared for their ability to clean and shape root canals in extracted human teeth. One technique was recommended by the manufacturer (Cavi‐Endo, Dentsply), while the other was a modification by the authors of the stepdown technique. Mesiobuccal root canals of molars were instrumented using these techniques, after which a silicone impression material was injected into the prepared canals. The roots were then split longitudinally and one half was stained for debris scoring while the silicone impressions were assessed for shape. The results showed that the modified technique produced significantly cleaner canals than the recommended technique. The shaping ability of both techniques was difficult to evaluate because of the complex morphology of molar root canals. The final shape of the prepared canal depended more on the initial shape than on the instrumentation technique.
Pulp responses to two strains of bacteria isolated from human carious dentine (L. plantarum) (NCTC 1406) and S. mutans (NCTC 10919)
Authors: PATERSON R. C. , WATTS A.
Published: September 2007

A series of studies has been conducted in which mono‐infected gnotobiotic rats were used to study the responses of the dental pulp to micro‐organisms isolated from carious lesions in dentine. In this study pulp responses to L. plantarum (formerly odontolyticus) (NCTC 1406) in pure culture and in combination with S. mulans (NCTC 1O919) are reported. The incidence of inflammation/necrosis/dentine bridge formation observed in animals monoinfected with L. plantarum was similar to that reported in previous germ‐free studies. There was a greater incidence of dentine bridge formation in rats monoinfected with L. plantarum compared with those monoinfected with S. mutans. When the two organisms were combined, periapical inflammation was observed in 14%of the teeth examined after 28 days, but there was no significant difference in the incidence of dentine bridge formation. Considerable variation in the density of staining of the two microorganisms in histological sections was observed.
Pulp response to, and cariogenicity of, a further strain of Streptococus mutans (NCTC 10832)
Authors: WATTS A. , PATERSON R.C.
Published: September 2007

The pulpal response to and cariogenicity of a third strain of Streptococcus mutans, namely S. mutans (NCTC 10S32), was studied in monoinfected gnotobiotic rats of the Fischer strain using the techniques described previously by the present authors. Unlike S. mutans (NCTC 10449 and 10919), S. mutans (NCTC 10832) was associated with the presence of inflammatory cell infiltrates in the coronal pulp of a small number of teeth and extensive periapical inflammation 28 days after the creation of untreated pulpal exposures. S. mutans (NCTC 10832) was associated with the presence of extensive pulpal necrosis and reduced dentine bridge formation. These changes were similar to those noted with the other two strains of S. mutans. S. mutans (NCTC 10832) was non‐cariogenic in monoinfected gnotobiotic rats of the Fischer strain.
Garré's osteomylitis: a case report
Authors: FERREIRA B. A. , BARBOSA A. L. B.
Published: September 2007

This is a case report of Garré's osteomyelitis caused by infection from a lower left molar which was successfully managed by root treatment following several unsuccessful attempts with antibiotic therapy alone. After 18 months there was complete resolution ofthe bony lesion.
Bacterial invasion of non‐exposed dental pulp
Authors: HOSHINO E. , ANDO N. , SATO M. , KOTA K.
Published: September 2007

Anaerobic procedures were adopted to demonstrate the early bacterial invasion of non‐exposed dental pulps, and to isolate and identify the bacteria. Of 19 freshly extracted teeth which originally exhibited deep dentinal lesions, clinical examination and electric pulp testing showed that nine of them had no pulpal exposure. Thus the pulps of these teeth were covered by clinically sound dentine beneath the carious lesion. Bacteria were found to have invaded the pulps of six of these nine teeth. The predominant bacteria were obligate anaerobes belonging to the genera Eubacleriiim, Propionibacterium and Actinomyces. Other obligate anaerobes were Lactobacilhis, Peptostreptococcus, Veillonella and Streptococcus. The bacterial composition resembled that of the deep layers of dentinal lesions described previously, suggesting that the bacteria isolated in this study had passed through some individual dentinal tubules, to invade the dental pulp.
Influence of surgical treatment of periapical lesions on serum and blood levels of inflammatory mediators
Authors: MARTON I. J. , KISS C.
Published: September 2007

Changes in the serum levels of immunoglobulin IgA, IgG, IgM, positive acute phase proteins and complement activity, as well as the lymphocyte subpopulations and the neutrophil leucocyte‐related chemiluminescence in the blood of patients with apical granuloma as related to endodontic and surgical treatment were investigated. Measurements were performed on admission, and 7 days and 3 months after the treatment. Elevated IgM concentration, positive acute‐phase protein levels and spontaneous whole‐blood chemiluminescence were noted at admission. However, a significant decrease in the serum level of each of the six investigated acute‐phase proteins, and in the spontaneous chemiluminescence of blood was observed during the 3‐month follow‐up period. The significant increase in serum complement activity following therapy suggests that complement fixation might have occurred in these patients. A significant increase in the ratio of early sheep erythrocyte rosette‐forming lymphocytes was also observed. The results of this study provide evidence for complete recovery after elimination of local inflammation by proper endodontic treatment and apicectomy in patients with apical granuloma.
The radiographic incidence of multiple roots and canals in human mandibular premolars
Authors: SERMAN N. J. , HASSELGREN G.
Published: September 2007

The aim of this study was to Investigate the incidence in mandibular premolars of multiple roots and root canals that could be demonstrated radiographically. The images of mandibular premolar teeth as seen on intra‐oral full‐mouth radiographic surveys (547) taken with the paralleling technique were examined. In 99 patients (18.1%) there was at least one premolar tooth with either divided canals or roots. First premolars were involved in 15.7% of patients, and second premolars in 7%.
A comparison of the dentine‐removing characteristics of two endosonic units
Authors: GULABIVALA K. , BRIGGS P. F. A. , SETCHELL D. J.
Published: September 2007

The purpose of this study was to compare the dentine‐removing characteristics of size 25 K‐files activated by the Cavi‐Endo and Piezon‐Endo units. The influence of power‐setting, direction of file oscillation, interfacial force and operator‐assisted movement were studied. Filing was performed on flat surfaces of dentine and impressions of the instrumented surfaces revealed characteristic patterns of dentine removal corresponding to the area of contact with the file which was quantified using a Reflex microscope.

Differences in dentine removal as affected by the power output of the two systems were only apparent when the maximum power‐setting on the Cavi‐Endo was compared with the maximum recommended for root canal preparation on the Piezon‐Endo. The Cavi‐Endo removed significantly more dentine than the Piezon‐Endo. When operator‐assisted movement of the file was superimposed, both systems removed significantly more dentine than without assisted filing. However, the Piezon‐Endo now removed significantly more dentine than the Cavi‐Endo. This difference was more apparent when the file oscillated perpendicular to the dentine surface, compared with oscillation parallel to the substrate. An increase in the interfacial force from 30 g to 60 g resulted in a greater reduction in dentine removal by the Cavi‐Endo compared with the Piezon‐Endo. Thus, at a 30 g interfacial force there were insignificant differences between the endosonic units but at 60 g, the Piezon‐Endo removed significantly more dentine than the Cavi‐Endo.

The dentine‐removing characteristics of the two endosonic units tested are very different under certain conditions. These findings may have important clinical implications.
Adaptation of injected thermoplasticized gutta‐percha in the absence of the dentinal smear layer
Authors: GUTMANN J. L.
Published: September 2007

The adaptation of thermoplasticized, injected gutta‐percha to prepared dentine devoid of smear layer was examined with SEM. Findings indicate a penetration of gutta‐percha into the patent dentinal tubules with or without root canal sealer. The clinical implications of these findings are discussed.
In vitro release of calcium and hydroxyl ions from two types of calcium hydroxide preparation
Authors: TAMBURIĆ S. D. , VULETA G. M. , OGNJANOVIĆ J. M.
Published: September 2007

Non‐setting and setting pastes are the most common forms of calcium hydroxide, used in endodontics. The aim of this study was to investigate the differences in the availability of calcium and hydroxyl ions from some commercial preparations of both types. In vitro released calcium and hydroxyl ions were determined by a potentiometric method, after diffusion through sintered glass.

The non‐setting pastes evaluated were Calcipulpe, Calxyl Red, Calxyl Blue and Cinacal; while setting base materials were represented by Dycal, Nu‐Cap and Reolit. The data obtained showed significantly higher availability of calcium and hydroxyl ions from non‐setting pastes, compared with‘alkaline cements’(P>0.05). Great variations in the amount of released ions were also found among samples of the same material.
Neural changes in ulcerative and hyperplastic pulpitis: a transmission electron microscopic study
Authors: PIŞKIN B. , AKTENER B. O. , KARAKIŞI H.
Published: September 2007

The purpose of this study was to examine at ultrastructural level the neural changes in human apical pulps of teeth clinically diagnosed as having ulcerative or hyperplastic pulpitis. Seventeen specimens were prepared from six teeth with ulcerative or hyperplastic pulpitis and four specimens from two sound teeth. After routine procedures the specimens were examined under an electron microscope for changes in the structure of myelinated and unmyelinated nerve fibres. Although the teeth used in this study responded positively to vitality test, the results revealed that moderate to severe degenerative changes occurred in the nerve fibres of the apical pulps of the teeth showing these two diseases.
The use of E‐speed film for root canal length determination
Authors: POWELL‐CULLINGFORD A. W. , FORD T. R. PITT
Published: September 2007

This study compared the use of D‐speed and E‐speed dental X‐ray film for assessing the working length of root canals.

Root canal files of varying size (ISO 06, 08, 10 and 15) were placed in the root canals of a maxillary molar and a mandibular molar in a dried skull and mandible. Files were set at various lengths relative to the radiographic apex. The X‐ray projections were kept constant. Exposure settings for the two film types that gave comparable radio‐graphic density were selected. Films were developed manually under standardized conditions. A total of 48 films of each type were examined at various magnifications by four trained examiners for the estimation of distance between the file tip and radiographic apex.

There were no differences between examiners in estimating working length. The effect of file size, root and magnification were also not significant. The differences between the film types were not significant (P<0.05).

It is concluded that clinicians should use E‐speed film instead of D‐speed film for root canal length measurement, because the exposure time was reduced by over 40% but the quality of the radiographic image was not significantly different.
Management of the resected root end: a clinical review
Authors: GUTMANN J. L. , FORD T. R. PITT
Published: September 2007

Careful management of the resected root end during endodontic surgery is critical to the overall success of the case. After resection, the root structure presents with multiple anatomical variations and considerations at both a macroscopic and microscopic level. These include root outline, canal anatomy, dentinal tubule configuration, presence of a smear layer and root canal filling material. Proper assessment of these variables will dictate the best methods for root‐end management, along with the attainment of an anatomically compatible root face for optimal healing of the periradicular tissues.
Factors influencing the success of conventional root canal therapy—a five‐year retrospective study
Authors: SMITH C. S. , SETCHELL D. J. , HARTY F. J.
Published: September 2007

This retrospective study on the outcome of conventional root canal therapy was carried out on patients attending the Eastman Dental Hospital between 1970 and 1982. A minimum follow‐up period of 5 years was required for patients to be included in the survey. The characteristics of the resulting sample group, the techniques for canal preparation and obturation and the obturating materials used were analysed. The type of obturating material used had no demonstrable effect on success rate but sex, age, preoperative vitality and periapical pathology were associated with significantly differing success rates. Technique also influenced success rate; the method of canal preparation and the position of the apical seal relative to the radiographic apex were both found to be significant. The overall success rate was 84.29%, representing 692 of 821 teeth included in the survey.
Determining periodontal ligament (PDL) cell vitality from exarticulated teeth stored in saline or milk using fluorescein diacetate
Authors: PATIL S. , DUMSHA* T. C. , SYDISKIS R. J.
Published: September 2007

One of the key factors for obtaining a favourable long‐term prognosis in avulsed teeth is maintenance of the vitality of the periodontal ligament (PDL) cells. Most studies which have examined PDL cell vitality have used neutral red or trypan blue as stains. However, these stains have certain inherent disadvantages. The purpose of this paper was to (i) evaluate the use of saline and milk as storage media for PDL cells and (ii) determine the value of using fluorescein diacetate (FDA) as a staining medium for vital PDL cells on the root surface of avulsed teeth. Thirty‐two single‐rooted premolars were utilized from patients aged 13 to 28 years. Following atraumatic extraction, the teeth in the experimental groups were air dried for 10 min and then placed in either milk or saline for 120 min. Both control and experimental teeth were subjected to trypsinization procedures, staining with FDA, and haemocytometer readings to determine the number of vital cells. There was no statistically signifi‐cant difference in the number of viable cells on the root surfaces of teeth after 2h of storage in either milk or in saline. Furthermore, staining with FDA provided an excellent method by which to determine PDL cell vitality.
The cervical window as an aid in root canal access
Authors: ALMEIDA C. M.
Published: September 2007

Access to the coronal opening of root canals may be very difficult in cases where cervical caries, whether treated or not, has developed. A direct view through a buccal opening, called a buccal window, was successfully used on two patients and is proposed for similar cases.
Mechanisms controlling secondary initiation of dentinogenesis: a review
Authors: TZIAFAS D.
Published: September 2007

Dentinogenesis can be initiated secondarily as an intrinsic ability of the dental pulp to repair, or after interaction of pulp cells with specific exogenous inductive factors. In the present article the basic develop‐mental aspects, highlighting the mechanism by which dentinogenesis is initiated during tooth development, are discussed. Furthermore, clinical and experimental observations concerning the events taking place during secondary initiation of dentine formation, as a part of exposed or non‐exposed pulp tissue repair, or as a result of dentine matrix or other chemical‐pulp cell interactions, are reviewed. Discussion includes hypotheses relating to the crucial biological steps leading to expression of odontoblastic‐like cell phenotype and secondary initiation of dentine histogenesis.
An apical leakage study in the presence and absence of the smear layer
Authors: KARAGÖZ‐KÜçÜKAY I. , BAYIRLI G.
Published: September 2007

The apical seal produced by low‐temperature injection of gutta‐percha, with or without root canal sealer, in the presence or absence of the smear layer was evaluated quantitatively using an electrochemical technique. The root canals of 44 teeth were prepared with the smear layer intact following a final flush of NaOCl (group 1), while the root canals of a further 44 teeth were prepared and the smear layer removed with a final flush with EDTA followed by NaOCl (group 2). Subgroups were obturated using Ultrafil System alone or accompanied by Calciobiotic Root Canal Sealer. Microleakage data was expressed as a percentage of apical leakage evident in each group. Statistical analysis of the results revealed that the groups obturated with Ultrafil alone showed no significant differences in leakage compared with the groups where sealer was used, either when the smear layer had been left intact or removed. (P>0.05). However, comparison of the combined two groups with smear layer present versus the combined two groups with smear layer removed showed a highly significant difference (P<0.01), with the incidence of leakage reduced in the absence of the smear layer.
Changes in patient age and tooth distribution for root canal treatment in a teaching hospital over a 15‐year period
Authors: MANOGUE M. , MARTIN D. M.
Published: September 2007

This study was undertaken to determine the changing pattern of root canal treatment undertaken by undergraduates in a teaching hospital over a period between 1976 and 1990 in terms of the incidence of root canal treatment, noting particularly changes in the types of tooth treated and in the age distribution of patients receiving treatment. It was found that the pattern of provision of root canal treatment has altered in recent years to involve a greater proportion of multi‐rooted posterior teeth. More treatment is also being provided for older patients. The trends are comparable with those that have occurred in general dental practice.
Biological perspectives on the non‐surgical endodonfic management of periradicular pathosis
Authors: MAALOUF E. M. , GUTMANN J. L.
Published: September 2007

Differential radiographic criteria are unreliable for the histological diagnosis of periradicular lesions of pulpal origin. It should not, therefore, be assumed that large lesions or lesions with an opaque border are cystic. Even if cystic, or if strands of epithelium are present, the literature supports repair following the removal of the source of the pathosis. In most cases, the aetiological factors are oral contamination through the root canal or degenerating pulpal tissue. Therefore, the mere surgical removal of lesions of pulpal origin without removing the causes through proper root canal cleaning, shaping and obturation, will not result in the healing of the periradicular tissues. In addition to removing effectively the causative factors, environmental changes in the periradicular tissues caused by the process of canal debridement may inherently aid in the demise of epithelium, when present. The salient issues are discussed in light of thorough debridement of the root canal system, coupled with postulated mechanisms for the resolution of lesions displaying epithelial stands or cavities. Likewise, the role of calcium hydroxide and its potential role in the alteration of the periradicular environment is addressed, with support for the repair of large periradicular lesions without surgical intervention.
Comparison of the quality of obturation following endosonic versus hand instrumentation
Authors: NATTRESS B. R. , YOUNGSON C. C. , MARTIN D. M. , CASSIDY M.
Published: September 2007

This study was undertaken to compare the quality of root canal obturation following preparation by endosonic or hand instrumentation. Forty single‐canal, extracted lower premolar teeth were selected. One group of 20 teeth was prepared using a standard step‐back technique, the other 20 teeth were prepared with an ultrasonic machine. The groups were subdivided, with two operators preparing 10 teeth of each group. The teeth were obturated by a third operator using cold laterally condensed gutta percha. The root apices were then immersed in methylene blue dye for 48 h and the teeth sectioned longitudinally. Image analysis recorded the amount of sealer and void within the obturated canal. The linear distance of dye penetration was measured to provide an indication of apical seal. Examination of the root canal shape resulting from the different preparation techniques used was also undertaken. No significant difference was noted in the percentage of sealer and void present in the root canals obturated after endosonic or hand instrumentation. There was a slightly greater although not significant increase in the degree of linear penetration of dye in canals prepared endosonically. The endosonic technique used in this study appeared to produce a canal preparation of slightly less continuous taper than that obtained with hand preparation.
An In‐vitro evaluation of the influence of canal curvature on the sealing ability of Thermafil
Authors: LEUNG S. F. , GULABIVALA K.
Published: September 2007

The sealing ability of lateral condensation and Thermafil were compared in root canals with curvatures either greater or less than 25 degrees. Forty‐eight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals in two groups had curvatures of less than 25° and the remaining two groups had canals with curvatures greater than 25°. Four canals acted as positive and negative controls. All canals were enlarged to accept a size 30 file to the working length and flared using the step‐back technique. Roth's sealer was used in all canals. Lateral condensation and Thermafil obturators thermoplasticized in an open flame were used to obturate two groups each of canals, one group with curvatures greater than 25° and the other less than 25°. After immersion in India ink, the teeth were rendered transparent and the linear penetration of dye measured. It was found that Thermafil sealed significantly better than lateral condensation in canals with curvatures greater than 25° (P < 0.05). However, there were no significant differences between the techniques in the groups with canal curvature less than 25°. There was no significant difference in the performance of each of the techniques when analysed with respect to canal curvature.
The effect of storage time on the degree of dye leakage of root‐end filling materials
Authors: HIGA R.K. , TORABINEJAD M. , MCKENDRY D. J. , MCMILLAN P. J.
Published: September 2007

The quality of the apical seal obtained by root‐end filling materials generally has been assessed by the extent of dye penetration. Most investigators have allowed the root‐end filling materials to set before they are tested. The purpose of this study was to evaluate if storage time had any influence on the amount of dye leakage.

Seventy extracted single rooted human anterior teeth were used. After removal of their anatomical crowns, the roots were instrumented, filled with gutta‐percha and Roth's sealer, and subjected to test conditions. The roots were coated with two coats of nail polish. Root ends were resected and class I cavities prepared. Sixty class I root‐end cavities were filled with with either amalgam, super EBA, or IRM (20 each). Ten roots in each group were placed immediately into India ink for 48 h, the other 10 were stored for 24 h before placement into the ink. Ten roots (five per group) were used as positive (gutta‐percha, no sealer) and negative (bone wax) controls. The roots were then demineralized, linear dye leakage was measured, and the data were evaluated statistically using ANOVA.

Super EBA, and IRM showed significantly less dye leakage than amalgam (P<0.0001). No significant difference existed between Super EBA and IRM. Storage time had no significant influence on the amount of dye leakage observed in this study.
In vitro temperatures produced by a new heated injectable gutta‐percha system
Authors: WELLER R. N. , KOCH K. A.
Published: September 2007

In vitro intracanal temperatures produced by the injection of high‐temperature thermoplasticized gutta‐percha were measured. Obturations of a standard root canal were performed using an Obtura II heated gutta‐percha system at temperature settings of 160, 185, and 200°C. There was an increase in the recorded temperatures in the root canal for all three temperature settings with the mean temperature range from 38, 52°C to 61.58°C.

The mean temperature of the empty heating chamber was also measured and was accurately indicated on the control unit. However, the mean temperature of the gutta‐percha in the heating chamber was almost 20°C cooler than expected at each of the three settings. Finally, there was more than a 100°C decrease in the mean temperature of the extruded gutta‐percha in relation to the temperature of the gutta‐percha in the heating chamber.

Several clinically relevant observations were noted. Each of these observations was related to the temperature setting of the Obtura II control unit.
Radicular penetration of hydrogen peroxide during intra‐coronal bleaching with various forms of sodium perborate
Authors: WEIGER R. , KUHN A. , LÖST C.
Published: September 2007

The development of external cervical root resorption following internal bleaching of discoloured pulpless teeth is associated with the use of hydrogen peroxide. The aim of the study was to determine radicular penetration of hydrogen peroxide following intracoronal bleaching with various forms of sodium perborate, 63 extracted human incisors were root filled and stained artificially. Standardized cementum defects were created on the mesial and distal aspects of the root directly below the cemento‐enamel junction (CEJ). Using the walking bleach technique all teeth were bleached for a 6‐day period, with replacement of the bleaching paste after days 1 and 3.

Sodium perborate monohydrate (MH), trihydrate (TRH) or tetrahydrate (TH) was mixed with H2O2 or H2O and subsequently placed intracoronatly 1 mm below the labial CEJ. The teeth were divided into six groups:

MH + H2O2(30%)(n=12);

TRH + H2O2(30%)(n=12);

TH + H2O2(30%)(n=12);

TH + H2O(n=12);

TH + H2O gel(n=12);

no bleaching paste (n= 3).

At baseline and at days 1, 3 and 6 the amount of H2O2 taken up from the surrounding medium of each root was indirectly recorded and calculated as p.p.m.

Almost all teeth of the experimental groups showed leakage of hydrogen peroxide compared to those of the control group. The radicular penetration of hydrogen peroxide was significantly higher in teeth of groups I and III than in those of groups IV and V (P≤ 0.001). In conclusion, the amount of hydrogen peroxide leakage depends, among other factors, on the form of sodium perborate used. The risk of post‐bleaching cervical root resorption may be diminished by using sodium perborate tetrahydrate in conjunction with H2O.
Ultrasonic root‐end preparation Part 1. SEM analysis
Authors: GUTMANN J. L. , SAUNDERS W. P. , NGUYEN L. , GUO I. Y. , SAUNDERS E. M.
Published: September 2007

Preparations of apical cavities in resected root ends using rotary burs, with and without citric acid rinse, and ultrasonic tips were compared based on the presence or absence of superficial debris and smear layer. Three groups of 20 extracted teeth each were prepared as follows; I, a size 010 round bur was used to prepare an apical cavity 2–3 mm down the long axis of the root; II, treatment as per group I followed by a 60‐s rinse with a solution of 10:3 (10% citric acid, 3% Fe2Cl3); and III, an ultrasonic retrotip was used to prepare a 2–3 mm deep apical cavity. Roots were grooved longitudinally, split and prepared for SEM analysis at ×100 and ×780 magnification. Examiners were calibrated to a standardized grading system. Extensive statistical analyses indicated statistically significant differences within and among the groups (P<0.05). Root‐end preparation with a bur created a heavy smear layer at all levels of the preparation. This layer was partially removed during ultrasonic preparation in the apical two‐thirds. A greater removal of the smear layer was achieved with the citric acid rinse (P<0.05). Coronally, root‐end preparations were contaminated with moderate to heavy amounts of debris with all techniques.
Histological healing following surgical endodontics and its implications in case assessment: a case report
Authors: MEYERS J. P. , GUTMANN J. L.
Published: September 2007

Following extraction of a symptomatic mandibular premolar which had been subjected to two periradicular surgical procedures, significant apical healing was identified histologically. The implications of these findings are discussed in relation to contemporary advocated treatment regimens, case assessment, and interpretation for success and failure.