bluuebunny/crossref_metadata_2025 huggingface dataset:
Success of pulpotomy in the management of hyperplastic pulpitis
Authors: CALISKAN M. K.
Published: September 2007

Hyperplastic pulpitis is a variety of chronic open pulpitis which is regarded as irreversible. This condition is usually treated by root canal treatment, unless coronal damage does not permit restoration, in which case extraction is indicated.

In the present study, 24 permanent teeth of individuals, aged 10–22 years and diagnosed as hyperplastic pulpitis were treated by pulpotomy using an atraumatic surgical technique with calcium hydroxide alone. The treatment was successful in 22 teeth, according to the following criteria: absence of clinical symptoms, absence of any intraradicular or periradicular radiographic pathological changes, presence of dentine bridge detected by clinical examination and sometimes observed radiographically, and sensitivity to electrical stimulation. The follow‐up examination ranged from 12 to 48 months.

The high frequency of clinical healing in this study appears to justify recommending pulpotomy as the treatment regime in selected cases of chronic hyperplastic pulpitis.
Fluid transport and bacterial penetration along root canal fillings
Authors: WU M.‐K. , GEE A. J. DE , WESSELINK P. R. , MOORER W. R.
Published: September 2007

Convective transport of water from the coronal to the apical end of obturated root canals was determined by the movement of an air bubble in a capillary glass tube connected to the apex of the experimental root section using a headspace pressure of 120 kPa (1.2 atm). Water transport through existing voids in the obturated canals could be measured reproducibly in this way. The root canals of 60 human maxillary canines were filled with gutta‐percha and sealer by the cold lateral condensation technique. Thirty of these were first exposed to a small motile bacterium, Pseudomonas aeruginosa, growing in a reservoir at the coronal end of each root. After 50 days, two specimens allowed penetration of bacteria to a reservoir at the apical end. All the roots were then assessed quantitatively for convective transport of water. The results were divided into three defined categories: 39 obturated canals were in the‘bacteria tight’category, 14 canals in the 'slight leakage’and 7 canals in the‘gross leakage’category. The two specimens that showed bacterial penetration fell into the slight and gross leakage categories. The previous test for bacterial passage did not statistically influence the fluid transport pattern of these roots which was measured subsequently. These findings indicate that fluids transport through obturated root canals, most of which do not allow the passage of bacteria.
The effect of using files with altered tips in a sonic handpiece: an in vitro study
Authors: DUMMER P. M. H. , HUTCHINGS R. , HARTLES F. R.
Published: September 2007

The objective of this study was to establish the effect of altering the non‐cutting tips on Shaper flies during canal preparation with the MM1500 Sonic Air handpiece. A total of 90 simulated canals in clear resin blocks of various angles and positions of curvature were prepared using Shaper files activated by an MM 1500 Sonic Air handpiece. Thirty canals were prepared with unmodified files having non‐cutting tips, 30 canals were prepared with files which had their tips removed completely and a further 30 canals were prepared with files which had tips reduced by half. All canals were prepared using an identical preparation procedure which involved a linear filing motion and an anticurvature technique in curved canals. The parameters investigated included loss of canal length, weight loss from the blocks, smoothness of canal walls, transportation and overall shape of the prepared canals. The effect of altering the file tips was to increase significantly the loss of working distance and the prevalence of canal aberrations such as zips and danger zones. Altering the tips also had a detrimental effect on the pattern and extent of transportation as well as widening canals excessively in their apical third. Overall, under the conditions of this study, alterations to the non‐cutting tips of Shaper files was counterproductive and resulted in canals displaying many adverse features. Conversely, retention of the non‐cutting tips allowed canal preparation to proceed rapidly and effectively producing canal shapes which displayed many desirable features.
Light‐cured glass ionomer cement as a retrograde root seal
Authors: CHONG B. S. , FORD T. R. PITT , WATSON T. F.
Published: September 2007

A light‐cured glass ionomer cement was investigated as a retrograde root seal, without a retrograde cavity. This was compared with the material used in a retrograde cavity, and with a conventional glass ionomer cement, as a seal. The adaptation and sealing ability of the test materials were assessed using a confocal optical microscope with a fluorescent dye.

The root canals of 40 extracted human single‐rooted teeth were prepared and filled with gutta‐percha and sealer. All the teeth were subsequently apicected, then divided into four equal groups. In one group, a retrograde cavity was prepared, and the light‐cured glass ionomer cement was placed as a retrograde root filling. No retrograde cavities were prepared in the three remaining groups. The light‐cured glass ionomer cement was applied directly onto the apicected root face. Two different thicknesses of light‐cured glass ionomer cement were tested, a thin layer (≈1 mm) in one group, and a thicker layer (<1 mm) in another group. A conventional glass ionomer cement was used in the last group, and applied directly onto the root face in a single thickness (≈1 mm).

In the group where the light‐cured glass ionomer cement was used in a retrograde cavity, the material was often well adapted to one cavity wall, but gaps were found on the opposite wall. The light‐cured and conventional glass ionomer cement retrograde root seals were well adapted to the root face, regardless of the thickness of material used.

The thinly applied (≈1 mm) light‐cured glass ionomer cement retrograde root seals permitted the least leakage. This was significantly less than the light‐cured glass ionomer cement used with a retrograde cavity (P > 0.001). The greatest extent of dye penetration was found with the thick (< 1 mm) light‐cured and conventional glass ionomer cement (≈1 mm) root seals; the differences between these were not significant. The light‐cured glass ionomer cement was only suitable as a retrograde root seal when a thin layer (≈1 mm) was used.
Radicular cyst affecting a root‐filled human tooth: a long‐term post‐treatment follow‐up
Authors: NAIR P. N. R. , SJÖGREN U. , SCHUMACHER E. , SUNDQVIST G.
Published: September 2007

Apical periodontitis is caused primarily by microorganisms residing in the root canals of affected teeth. Nevertheless, there is convincing evidence implicating other independent factors that adversely affect the outcome of conventional root canal therapy. In this paper, morphological evidence is presented in support of die potential role of two endogenous factors that may interfere with post‐endodontic healing of the periapex. The specimens consisted of a surgical biopsy of an asymptomatic peri‐apical lesion which persisted for a follow‐up period of 44 months. The biopsy was processed for correlated light and electron microscopy. The lesion was characterized by the presence of a large central lumen lined by a stratified squamous epithelium. The most striking feature of the lesion was the presence of vast numbers of cholesterol crystals which congregated in the connective tissue surrounding the cyst cavity. Extensive light and electron microscopic investigation of the apical part of the root canal and the lesion foiled to reveal the presence of microorganisms.

These findings strongly suggest that intrinsic factors like the accumulation of certain tissue break‐down products such as cholesterol crystals, and the cystic condition of the lesion itself, can adversely affect the healing process of the periapex following root canal therapy. Consequently, such apical lesions can remain refractory to conventional endodontic therapy for long periods of time.
A comparative scalability study of different retrofitting materials
Authors: ÖZATA F. , ERDILEK N. , TEZEL H.
Published: September 2007

The purpose of this study was to compare the sealing ability of high‐copper amalgam, glass ionomer cement, and silver glass ionomer cement as retrofitting materials when used with and without varnish. Seventy extracted human single‐rooted anterior teeth were instrumented and the root canals obturated with laterally condensed gutta‐percha and sealer. The apical 3 mm of each root was resected and a 2 mm‐deep apical Class I preparation cut. The roots were then randomly allocated to six groups of 10 teeth and retrofitled with one of die experiment materials. Group I comprised high‐copper amalgam; group 2, high‐copper amalgam with cavity varnish; group 3, glass ionomer cement without varnish: group 4, glass ionomer cement with varnish; group 5, silver glass ionomer cement without varnish; and group 6, silver glass ionomer cement with varnish. Two groups of five roots each were used as positive and negative controls.

The root surfaces were coated with nail polish and specimens immersed in 2% methylene blue solution for 14 days. After vertical sectioning, dye penetration was examined under a stereomicroscope. The results of the study were analysed statistically. The sealing ability of the conventional glass ionomer cement with varnish was significantly better while dye penetration was higher in silver glass ionomer cement without varnish group than the other groups (P > 0.01).
Maxillary permanent incisors with two root canals: a report of two cases
Authors: REID J. S. , SAUNDERS W. P. , MACDONALD D. G.
Published: September 2007

The root canal treatment of permanent maxillary incisors with two root canals is reported. Two cases are presented, one success and one failure, with discussion regarding the different outcome, highlighting the need for careful radiographic investigation and patient management.
Dental anxiety: a cause for possible misdiagnosis of tooth vitality
Authors: ELI I.
Published: September 2007

Fear, anxiety and anticipation of pain are prepotent emotional and cognitive mediators of pain behaviour. As pain is often used as a parameter for evaluation of tooth vitality, existing dental anxiety may occasionally lead to possible misdiagnosis. A representative case is presented in which dental anxiety led to an initial misdiagnosis of endodontic pathology.
Root canal morphology of maxillary permanent first molar teeth at various ages
Authors: THOMAS R. P. , MOULE A. J. , BRYANT R.
Published: September 2007

The root canal anatomy and pulp chamber morphology of 216 maxillary permanent first molar teeth of known age was examined using a radiographic technique after infusion of the root canal system with a radiopaque sodium iothalontate gel. This technique proved to be a rapid and effective method for the examination of root canal morphology and is recommended when root canal anatomy needs to be examined before further investigations are carried out.

Over 95% of palatal and disto‐buccal roots contained a single root canal. The mesio‐buccal root was more complex. All types of configurations were seen. Only 26% of mesio‐buccal roots showed a single canal.

The pulp canal in all roots appeared to narrow at an early age. In the mesio‐buccal root, a definite two‐directional calcification pattern was apparent in most teeth by the age of 10. The rate of progress of root formation was very variable.

There was no apparent relationship between the type of canal system in the mesio‐buccal root and the type of canal orifice present.

The transverse cross‐sectional shape of the pulp chamber was trapezoidal in 81% of teeth.
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

The 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

Evaluation 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

The 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

A 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

Natural 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

Endodontic 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

The 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

Progression 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

Patients 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

The 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

The 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

The 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

The 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

The 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

The 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

An 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

The 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.
Detection of leukotriene C4 in human periradicular lesions
Authors: COTTI E. , TORABINEJAD M.
Published: September 2007

The purpose of this study was to determine the concentration of leukotriene C4 (LTC4), a potent inflammatory mediator, in human symptomatic and asymptomatic periradicular lesions. Periradicular lesions from each of six asymptomatic and symptom‐atic patients were obtained. Six pulps from unerupted third molars served as the negative controls, six samples of chronically inflamed gingival tissues served as the positive controls. All samples were immediately frozen in liquid nitrogen. The concentration of LTC4 was determined by reverse‐phase high‐pressure liquid chromatography. Representative samples from each group were fixed in formalin, sectioned and stained with haemotoxylin and cosin. The concentrations of LTC4 found in the periradicular lesions were signifi‐cantly higher than those in uninflamed pulpal tissue (P=0.027). However, no statistically significant difference was found between the concentration of LTC4 in the periradicular lesions of the symptomatic patients and those found in the asymptomatic patients and in the samples of the chronically inflamed gingival tissue (P>0.05).

This data would suggest that among other inflam‐matory mediators, LTC4 participates in the patho‐genesis of human periradicular lesions.
Retreatment decision making by a group of general dental practitioners in Germany
Authors: HÜLSMANN M.
Published: September 2007

The aim of this study was to evaluate whether retreatment of root fillings was judged necessary or not and which kind of retreatment was preferred among a group of general dental practitioners in Germany. A questionnaire comprising 19 cases of endodontically treated teeth with different case histories and several treatment options was sent to all general practitioners in Göttingen (Germany). The cases included teeth with periapical radiolucencies, pain, apical resorption, under‐ and overfilling, and unfilled root canals. Results obtained from 43 questionnaires returned indicate that non‐intervention or further radiographic monitoring were preferred by the majority of general practitioners in 10 of 19 cases, even in the presence of periapical pathosis. Only five cases were judged to require conservative endodontic retreatment and, in four cases, root resection. The results revealed large inter‐ and intra‐individual discrepancies in the estimation of endodontic retreatment need.
Radiographic simulation of a periapieal lesion comparing the paralleling and the bisecting‐angle techniques
Authors: FORSBERG J. , HALSE A.
Published: September 2007

Sixty apical areas of single‐rooted teeth were examined in this study. A simulated periapical lesion was produced using an acrylic sphere (diameter 2.0 mm), the surface of which was covered with a thin layer of zinc cement. The sphere was placed in close contact with the apical foramen using a thin orthodontic wire inserted into the apical portion of the root canal. The correctly adjusted parallel projection depicted the simulated lesion with a very low degree of error. Overangulation of the central beam with maintenance of parallelism between tooth and film resulted in a moderate degree of magnification.

When correctly adjusted, the bisecting‐angle technique produced images with almost the same accuracy as the paralleling technique. Over‐angulation resulted in most images showing a reduced size of the simulated lesion. Moderate under‐angulation most often recorded the correct dimension of the globe. In some cases a magnified image of the sphere was produced. Generally, this was associated with a palatally curved root. The investigation thus clearly indicated that the paralleling technique provides the most reliable information about the extent of a pathological process.
A model system for evaluating filing technique
Authors: LUMLEY P. J. , WALMSLEY A. D. , HARRINGTON E. , MARQUIS P.
Published: September 2007

The aim of this study was to develop a model system to demonstrate the pattern of load and how much is applied. A lower molar was mounted on a beam and attached to a mandibular phantom head jaw. A strain gauge fitted to the beam allowed loading of the molar to be recorded, during root canal preparation. Ten operators were asked to instrument the distal root canal; after preparation the operators were shown a graphical representation of the loads applied. This formed the basis of discussion and instruction in filing technique. The operators then repeated the filing. The results showed that prior to instruction operators used a push‐pull motion, applying a constant lateral force to the canal wall. After instruction and discussion of the graphical representation of the loads applied the stroke rates used were slower and loads applied were higher (two‐sample t‐test, n=10, P<0.01). The experiment was repeated 1 year later and this showed that the change in technique had been retained. In conclusion, this model system allows visual feedback to the operator and can be used as an aid to teaching filing technique.
Allergy to sodium hypochlorite during root canal therapy: acase report
Authors: ÇALIŞKAN M. K. , TÜRKÜN M. , ALPER S.
Published: September 2007

Sodium hypochlorite (NaOCl), is the most popular irrigation solution used in root canal treatment but it is known to be an irritant to vital tissues. There have been many case reports dealing with toxic effects of this material. Although the allergic potential of NaOCl has been described in the medical literature, only one case of known hypersensitivity to NaOCl has been reported in the dental literature. In this paper a case is presented, describing both local and systemic adverse tissue reactions, caused by an allergic response, after NaOCl irrigation.
Cytotoxicity studies of dental restorative materials using human periodontal ligament cells in vitro
Authors: ADAMS A. M. , SOAMES J. V. , SEARLE R. F.
Published: September 2007

A model that simulates conditions of clinical practice In vivo and allows extended exposure of test cells to test substances, was evaluated In vitro by screening the toxicity of seven dental restorative cements. Millipore filter discs, 0.45 μm pore size, or preserved dentine slices were used as diffusion barriers between test cells and test substances. Cytotoxicity was assessed by estimating cell loss from monolayers and by evaluating cytopathic changes in cultured cells. After 24 h exposure to the test materials results were in general agreement with reported observations from similar studies. However, extended exposure to composite resins gave rise to severe cytotoxicity, which has not been reported previously. In addition, monitoring of cultures by inverted microscopy demonstrated attempts at recovery in damaged monolayers with viable cells migrating and proliferating into areas of earlier cell loss. This supports observations In vivo of transient pulpal injury associated with the corresponding materials.
A morphometric analysis of the cross‐sectional area of dentine occupied by dentinal tubules in human third molar teeth
Authors: DOURDA A. O. , MOULE A. J. , YOUNG W. G.
Published: September 2007

The number and the mean percentage tubular cross‐sectional area of dentinal tubules per square millimetre were calculated in specimens of coronal dentine of 13 intact human third molar teeth from patients 18 to 28 years of age. The dentine was fractured at various known distances from the dentino‐enamel junction. Near the dentino‐enamel junction the number of tubules per square millimetre was 22 000 and the mean tubular cross‐sectional area was 3.6%. Midway between the pulpal wall and the dentino‐enamel junction the number of tubules was 37000 mm−2 and the mean tubular cross‐sectional area was 6.2%. Close to the pulp the number of dentinai tubules was 48000 mm−2 and the mean cross sectional area of tubules was 10.2 percent. The number of tubules per square millimetre more than doubled and the area occupied by tubules increased threefold from the dentine close to the dentine ‐enamel junction, to that close to the pulp. These differences in tubular patterns at different depths in dentine are clinically significant in dentine permeability, the treatment of traumatized teeth, and pain transmission in dentine.
Physical mechanisms governing the hydrodynamic response of an oscillating ultrasonic file
Authors: ROY* R. A. , AHMAD* M. , CRUM L. A.
Published: September 2007

Ultrasonically driven vibrating files are known to enhance the efficiency of root canal debridement. This paper presents a phenomenological view of the hydrodynamic response of an oscillating ultrasonic file and the relationship between the file response and various physical factors such as file size and curvature, file surface properties, file velocity amplitude, root canal geometry, and the type of irrigant. Relevant hydrodynamic properties include the propensity of a file to produce stable and transient cavitation, steady streaming, and cavitation microstreaming.

These relationships were explored by experiment. Sonoluminescence was employed as an indicator of transient cavitation activity and photographic analysis was utilized as a means for detecting steady streaming, microstreaming, and stable cavitation. Measurements failed to indicate any strong correlation between registered driving power and the propensity to produce transient cavitation. Files that were pitted or possessed salient edges were very effective at generating transient cavitation. When observed, transient cavitation activity generally occurred near the tip of the straight file, provided the wall‐loading did not inhibit file motion. In all cases studied, steady streaming and stable cavitation were observed to varying degrees, depending on the amount of file to wall contact. Stable cavitation was probably enhanced by the addition of moderate amounts of dissolved gas into the irrigant. Although the imposition of file–wall contact served to inhibit the production of transient cavitation, this action had relatively little effect on the ability of a file to produce a nominal level of streaming, microstreaming, and stable cavitation.

The relationship between these hydrodynamic properties and the process of root canal debridement is addressed. Observations suggest that it is not prudent to ascribe enhanced cleaning effects to any one phenomenon, for it is likely that several factors are involved to varying degrees depending on the local conditions of application.
In vitro evaluation of apical leakage of root canal fillings after in situ obturation with thermoplasticized and laterally condensed gutta‐percha
Authors: VEIS A. A. , MOLYVDAS I. A. , LAMBRIANIDIS T. P. , BELTES P. G.
Published: September 2007

The purpose of this investigation was to compare In vitro the sealing ability of root canal treatments performed In situ with injected thermoplasticized gutta‐ percha compared with the lateral condensation technique. Thirty single‐rooted teeth with straight canals, due for extraction For orthodontic or periodontal reasons were prepared using a step‐back technique. Teeth were then divided randomly into groups A and B and obturated, respectively, with the sectional injection thermoplasticized gutta‐percha and the lateral condensation techniques. Teeth were extracted after 15 days, immersed in India ink for 3 days and the leakage was determined using area‐metric analysis. The roots were ground transversally and the root portion was incrementaly removed with successive steps of 250 μm each, up to the coronal level of the dye penetration. Every section was photographed with a stereoscopic microscope under the same magnification (×20); 310 photographs were taken. Measurements of the area covered by ink as well as the whole cross‐sectional area of the canal were made from each photograph with the aid of a digitizing computer.

The measurements were subjected to non‐parametric statistical analysis. No significant difference was found (P>0.05). The technique of lateral condensation proved to be better in the first five sections (1.2 mm from the foramen) while thermoplasticized gutta‐percha technique was superior in the rest of the root canal.
Dentine tubule infection and endodontic therapy implications
Authors: OGUNTEBI B. R.
Published: September 2007

A critical review of the literature suggests that the microenvironment of dentinal tubules appears to favour the selection of relatively few bacterial types irrespective of the aetiology of the infection process; coronal dental caries or pulpar necrosis. These bacteria may constitute an important reservoir from which root canal infection and reinfection may occur following pulp necrosis or during and after endodontic treatment. Previous studies of this microflora have utilized microbiological culture techniques which need to be supplemented by those that allow In situ demonstration as well as identification of the bacteria. Newer treatment strategies that are designed to eliminate this microflora must include agents that can penetrate the dentinal tubules and destroy these microorganisms, since they are located in an area beyond the host defence mechanisms where they cannot be reached by systemically administered antimicrobial agents.