bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermomechanical compaction of gutta‐percha: effect of speed and duration
Authors: BEATTY R. G. , VERTUCCI F. J. , HOJJATIE B.
Published: September 2007

Summary. The McSpadden technique of obturating root canals with thermoplasticozed gutta‐percha has been used for several years, however the technique has been criticized, among the disadvantages is temperature elevation at the root surface. The objective of this study was to test the hypothesis that the McSpadden technique when used at higher speeds or for longer time than recommended by the manufacturer would result in a temperature rise at the root surface and would also have a determental effect upon linear apical leakage.

Niney maxillary incisors were divided ino six groups of 15 teeth whose root canals were prepared and subjected to different filling techniques: 5000 rev/minute for 5 seconds, 10,000 rev/minutee for 5 second, 10,000 rv/minute for 15 minute for 15 seconds, and laterally condensed gutta‐percha. Temperatures were measured by suing two J‐type thermocouples which were at the surface of each root.

A strobe was used to controsl the speed of instrument rotation and a stop‐wathch was employed to time each compaction. After obturation the teeth were placed into 1 per cent methylene blue dye for 2 weeks, then the linear extent of dye penetration was measured. Statistical analysis of the data showed that the influence of speed duration of compaction were significant in causing a temperature rise and apical leakage. The results of this study support the hypothesis that the use of the McSpadden technique at a higher speed or for longer duration than recommedned can cause an adverse temperature rise at the root surface and a detrimental effect upon the quality of the apical seal.
Self‐inflicted injury facilitated as a result of endodontic therapy: a case report.
Authors: LEVINKIND M. , AHLBERG K.F.
Published: September 2007

Summary. This report decribes a case in which a traumatized maxillary incisor was receiving endodontic treatment and this enabled the patient to force sveral foreign bodies through the tooth's incompletely formed aped into the periapical tissures. Recommendations are made for preventing this situation from arising.
A further study of the antibacterial properties of dental restorative materials
Authors: TOBIAS R. S. , RIPPIN J. W. , BROWNE R. M. , WILSON C. A.
Published: September 2007

Summary. The antibacterial activity of five dental materials (a calcium hydroxide base, a composite resin, a polycarboxylate cement, a conventional amalgam and a high copper amalgam) was investigated in vitro, an agar well technique previously described (Tobias et al. 1985). Six micro‐organisms, isolated from ferret plaque (Moraxella spp., Escherichia coli Corynebactrium sppk, Actinomyces viscosus, Enterococcus, and Streptococcus sagnuis), were studied. All the materials showed some antibacterial activity when freshly mexed but the activity varied between micro‐organsism. The two amalgams and the polycarboxylate cement were most active against Corynebacterium spp., whereas the composite resin and calcium hydroxide base showed the greatest activity aginst Moraxella spp. A marked reduction in the antibacterial acitvity of all materials occurred after sttting for 1 and 7 days. The relationship between the antibacterial activity of the marerials in vitro and the microbial leakage at the interface of material and vavity wall, and the pulpla response in vivo is discussed.
Pulp response to and cariogenicity of, a strain of of Streptococcus mutans
Authors: PATERSON R. C. , WATTS A.
Published: September 2007

Summary. Gnotobiotic rats mono‐infected with Streptococcus mutans (NCTC 10919) were maintained on a high sucrose diet in an isolator. When they were 8 weeks old the pulps of their maxillary first and second molars were mechanically exposed and left open to the oral environment. The rats were sacrificed in groups after 7 and 28 days. Thirty‐seven teeth were available for study in the 7‐day group, and 30 teeth in the 28‐day group. The test S. mutans was non‐cariogenic. After 7 days, necrosis of the superficial layers of the pulp was noted; however, after 28 days pulpal necrosis was much more extensive and calcific repair was observed in only one‐third of the teeth examined. The microorganism did not provoke inflammation in the pulp or periapical tissues. This is the second strain of S. mutans tested in this manner. These results are very similar to those reported previously for S. mutans (NCTC 10449) and strengthens the view that organisms of the S. mutans group have a low pathogenicity for the pulp.
The antibacterial properties of four elements released from dental restorative materials
Authors: NOUROLLAHI M. , MERYON S. D.
Published: September 2007

Summary. The antibacterial activity of four elements (zinc, copper, fluoride and mercury), previously reported to be released from dental restorative materials, was investigated. This was carried out using two aerobic micro‐organisms isolated from dentine beneath cavities in the ferret. These were grown in the presence of the test elements over a concentration range of 10–100 μg/ml for 72 hours. Concentration and exposure time were found to have a highly significant effect on the growth and viability of both micro‐organisms. Zinc, mercury and copper exerted the greatest effect, fluoride the least.
The sealing ability of injection‐moulded thermoplasticized gutta‐percha
Authors: BRADSHAW G.B. , HALL A. , EDMUNDS D.H.
Published: September 2007

Summary. The root canals of 120 single rooted teeth were prepared with files and then divided randomly into twelve subgroups. Four operators each filled three of these subgroups, one group with laterally condensed gutta‐percha, one group with thermoplasticized gutta‐percha with sealer and one group with thermoplasticized gutta‐percha without sealer. The fillings were assessed radiographically and a dye penetration test was used to investigate the leakage.

The lowest leakage values were found in those canals filled with laterally condensed gutta‐percha. The sealing ability of thermoplasticized gutta‐percha was enhanced by the use of a sealer. There was greater variation between operators in those groups where thermoplasticized gutta‐percha was used.
The effectiveness of different endodontic irrigation procedures on the removal of the smear layer: a scanning electron microscopic study
Authors: CIUCCHI B. , KHETTABI M. , HOLZ J.
Published: September 2007

Summary. To compare the effectiveness of different irrigation procedures on the removal of the smear layer, 40 curved canals were manually prepared in vitro under copious irrigation with 3 percentb NaOCI. Ten canals served as controls. The remaining 30 were equally distributed in three experimental groups and subsequently irrigated with the following: ultrasound with EDTA. In the scanning electron microscope, the appearance of the smear layer was rated over sthe distribution of dentinal tubule openingls for the coronal, middle and apical segmentsl of the canals. Irrigation with NaOCl produced consistently smeared surfaces. Ultrasonic stirring of NaOCl removed the smear layer moderately, while EDTA produced almost smear‐free surfaces. Ultrasound in association with EDTA did not enhance the dissolving capability of this chelating agent. A definite decline in the efficiency of the irrigation procedures was also observed along the apical part of the canals.
A clinical and roentgenological study of 55 cases of root perforation
Authors: KVINNSLAND I. , OSWALD R. J. , HALSE A. , GRØNNINGSÆTER A. G.
Published: September 2007

Summary. The treatment outcome of 55 root perforations in man were related to pretreatment conditions and various treatment procedures used, with a mean recall period of 3 years 5 months. In this study maxillary teeth were perforated three times more often (74.5 per cent) than mandihular teeth (25.5 per cent); 47 per cent of the perforations were due to endodontic and 53 per cent due to prosthodontic treatment. The buccal and mesial root surfaces as well as the midroot areas w ere most often perforated. In 25 per cent, radiographic changes were directly related to the perforated areas.

Twenty‐eight perforations were repaired by orthograde fillings with gutta‐percha and Kloro‐percha N‐ø; eight received a combined orthograde and surgical repair, and in only three cases a surgical approach was used. Four cases received no treatment but were recalled, and twelve perforations showed a size and location hopeless for repair; the teeth were therefore extracted. Five failures of the primary orthograde treatment group later underwent surgical treatment and were followed up for 3 years 3 months.

The overall success rate in the primary treatment group of teeth was 56 per cent while 36 per cent became failures. Five failures were retreated, and four of these became successful. A combined orthograde and surgical repair of the perforations provided the most favourable outcome with 92 per cent successful.

The study stresses the importance of preventing this type of treatment complication.
Shaping of simulated root canals in resin blocks using files activated by a sonic handpiece
Authors: DUMMER P. M. H. , ALODEH M. H. A. , DOLLER R.
Published: September 2007

Summary. . A total of 50 simulated root canals in clear resin blocks with various degrees and positions of curvature were prepared by either K‐files or Hedstrom files. Each file type was used to prepare 25 canals employing an in/out circumferential filing motion. The efficacy of the files was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. Overall, canal shaping with Hedstrom files was quicker and more effective. Both file types prepared straight canals in an appropriate manner but the majority of prepared curved canals were hourglass in shape. In general, K‐files created zips which were wider and thus more pronounced than those produced by Hedstrom files. Wide ‘danger zones’ were also regularly created. The location of the aberrations depended largely on the original shape of the canal and in particular on the position of the beginning of the canal curve. Under the conditions of this study, the manipulation of K‐files and Hedstrom files in a simple in out circumferential filing motion proved an unsatisfactory method of shaping simulated curved root canals in resin blocks.
A comparison of the ability of K‐files and Hedstrom files to shape simulated root canals in resin blocks
Authors: ALODEH M. H. A. , DUMMER P. M. H.
Published: September 2007

Summary. A total of 50 simulated root canals in clear resin blocks with various degrees and positions of curvature were prepared by either K‐files or Hedstrom files. Each file type was used to prepare 25 canals employing an in/out circumferential filing motion. The efficacy of the files was assessed by instrumentation time, deformation and fracture of instruments, and loss of working distance. The shape of the prepared canals was assessed by direct observation and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. Overall, canal shaping with Hedstrom files was quicker and more effective. Both file types prepared straight canals in an appropriate manner but the majority of prepared curved canals were hourglass in shape. In general, K‐files created zips which were wider and thus more pronounced than those produced by Hedstrom files. Wide ‘danger zones’ were also regularly created. The location of the aberrations depended largely on the original shape of the canal and in particular on the position of the beginning of the canal curve. Under the conditions of this study, the manipulation of K‐files and Hedstrom files in a simple in out circumferential filing motion proved an unsatisfactory method of shaping simulated curved root canals in resin blocks.
Capacitance effect of rubber gloves on electric pulp testers
Authors: TREASURE P.
Published: September 2007

Summary. Electric pulp testers (EPTs) are widely used to assess tooth pulp vitality. With many unipolar EPTs the electrical circuit is completed through the operator. Since dentists now routinely wear rubber gloves, these might be expected to provide electrical insulation, and therefore to break the circuit. The objective of this investigation was to define the electrical effect of wearing rubber gloves.

Two battery‐powered unipolar EPTs were examined using a digital storage oscilloscope with an input impedance of 1 MΩ. The probe tip was connected directly to the positive input lead of the oscilloscope. Three conditions were tested: (i) with the conductive handle connected directly to the negative input lead; (ii) with the ungloved operator holding the negative input lead in one hand and the conductive handle of the EPT in the other; and (iii) holding the conductive handle in a gloved hand.

While the two EPTs produced different patterns of voltage spike, for each there was no difference between conditions (i) and (ii). However, when the conductive handle was held in a gloved hand (condition iii), there was a reduction in peak negative voltage and a change in wave form with positive overshoot. The alteration in wave form could be reproduced by substitution of the operator's gloved hand with a capacitance of 47 pF.

These results support the hypothesis that a rubber glove acts partly as a capacitor in series with the electric pulp tester, and will alter the performance of EPTs unless the glove is bypassed electrically.
Evaluation of dowel space preparation on the apical seal using an image processing system
Authors: DE NYS M. , MARTENS L. , DE COSTER W. , THYS M.
Published: September 2007

Summary. The effect of post preparation on the apical seal of endodontically treated specimens was studied. The canals prepared in bovine bone were instrumented and obturated using five obturation techniques: the silver point technique, the lateral condensation of gutta‐percha technique, the warm vertical condensation of gutta‐percha technique, the Hygenic Ultrafil injection system and the Obtura technique.

In addition to these five control groups, the five experimental groups were also subjected to post preparation. In the latter group, the gutta‐percha was removed with an engine‐driven root canal reamer 48 hours after obturation. Both the control and experimental groups were suspended in a 0.5 per cent crystal violet solution for 48 hours. After dye penetration, the specimens were immersed in liquid nitrogen and then split longitudinally.

Linear measurements of the resultant apical dye leakage were determined by image processing. For each obturation technique, all specimens in both the control and experimental groups were recorded if they showed leakage.

Using Fisher's exact probability test, it was shown that there was no significant difference between the obturation techniques used.
The incidence of postoperative pain after canal preparation of open teeth using two irrigation regimes
Authors: SULONG M. Z. A. MOHD
Published: September 2007

Summary. This study was carried out to evaluate the incidence of postoperative pain in 68 patients requiring root canal therapy. The teeth studied contained non‐vital pulps and each had an existing open communication between the root canal and the oral cavity. Solvidont1 irrigating solution and medication paste were used on a group of 36 patients, while a second group of 32 patients had sterile isotonic sodium chloride2 (SISC) as the canal irrigant; no medicament was used on the second group. Three out of 36 patients (8 per cent) had mild discomfort following the use of Solvidont irrigant and paste. In the SISC group, 10 out of the 32 patients (31 per cent) complained of pain ranging from moderate discomfort to severe pain with associated swelling of soft tissues. Statistical analysis showed that the incidence of postoperative pain was high when the root canals of open teeth were not medicated.
Polydam—polythene sheet, a practical alternative to rubber dam for patients allergic to rubber compounds
Authors: PATTERSON C. J. W.
Published: September 2007

Summary. An alternative to rubber dam is required to ensure nasopharyngeal protection during endodontic procedures on patients who are allergic to rubber compounds. The use of polythene sheeting as a practical alternative is described, illustrated and discussed.
Shaping of simulated root canals in resin blocks using the step‐back technique with K‐files manupulated in a simple in/out filing motion
Authors: ALODEH M. H. A. , DOLLER R. , DUMMER P. M. H.
Published: September 2007

Summary. A total of 60 simulated root canals in clear resin blocks of various lengths and degree of curvature were prepared by hand with K‐files using a step‐back enlargement technique. The instruments were manipulated exclusively with a simple in/out filing or rasping motion with no attempt at roatation or twisting. The preparation technique was assessed by instrumentation, deformation and fracture of instruments, and loss of working distance. The shape of the preepared canals was assessed by direct inspection and from composite photographic prints produced by superimposing negatives of the canals obtained before and after preparation. In general, the preparations were time consuming and tedious to complete. Deformation and separation of instruments occurred mainly in those canals with short, severe curves. Loss of working distance was a universal finding and was associated to a degree with the straightening of curved canals inherent in their preparation. Prepared straight canals displayed a continuously tapering form being narrowest at their end‐points. On the other hand, prepared curved canals were invariably hourglass in shape. Under the conditions of this study the manipulation of K‐files in a simple in/out filing motion proved an unsatisfactory method of preparing simulated curved root canals in resin blocks.
The oscillatory pattern of sonically powered endodontic files
Authors: WALMSLEY A. D. , LUMLEY P. J. , LAIRD W. R. E.
Published: September 2007

Summary. When operated in air, the sonic endodontic instrument produced a movement at the driver head which resulted in a large elliptical oscillation of the file. This motion had similar properties to ultrasonically operated files in that there was a distinct variability in the magnitude of the vibratory motion between files of different design, length and thickness. When the sonic file was loaded, the elliptical motion was eliminated leaving a pure longitudinal file oscillation. This mode of vibration was particularly efficient as it was largely unaffected by loading, with the displacement amplitude being similar for different types of file used. The oscillatory pattern of the sonic file may offer a useful mode of mechanically assisted root canal preparaton.
Antibody formation to dog pulp tissue altered by a paste containing paraformaldehyde
Authors: WU M.‐K. , Wang M.‐E. , Chang S.‐P.
Published: September 2007

Summary. Pulpotomy treatment was performed weekly on the teeth of four dogs for 5 weeks. Antibody formation to pulp tissue altered by parafor‐maldehyde paste within the pulp cavity was measured by enzyme linked immunosorbent assays (elisa). The results indicated that the reaction between antigen and antibody did occur when pre‐treatment or post‐treatment serum reacted with the antigen of either the pulp tissue incubated with saline or that incubated with paraformaldehyde paste. No evidence was found to prove that antibody formation was related to the pulpotomy treatment with paraformaldehyde paste.
A surgical approch to the obturation of apically flared root canals with thermoplasticized gutta‐percha
Authors: DAWOOD A. J. S. , PITTFORD T. R.
Published: September 2007

Summary. Two cases are presented in which api‐cally flared root canals have been successfully obturated with thermoplasticized gutta‐percha, following the failure of existing root fillings.
Ludwig's angina: an unusual sequel to endodotic therapy
Authors: TUFFIN J. R.
Published: September 2007

Summary. Ludwig's angina is an unusual sequel to endodontic treatment: such a case is described Principles of management are discussed with emphasis placed on the need to secure the airway early. The literature is reviewed.
A comparison of one versus two appointment endodontic therapy in teeth with non‐vital pulps
Authors: FAVA L. R. G.
Published: September 2007

Summary. A clinical study using upper central incisors was carried out to evaluate the incidence of postoperative pain after root canal preparation by the double‐flared technique. Sixty teeth with necrotic pulps from 48 patients whose ages ranged from 12 to 65 years were prepared and filled in either one or two appointments. No difference was observed in the incidence of postoperative pain between the two groups.
Dentinal tubules at the root ends of apicected teeth: a scanning electron microscopic study
Authors: TIDMARSH B. G. , ARROWSMITH M. G.
Published: September 2007

Summary. Two groups of teeth, one of which contained teeth of known age, were examined by scanning electron microscopy to ascertain the presence of a potential pathway for leakage at the root ends of apicected teeth. At a point approximately 3 mm from the apex, a level chosen as being typical for apicectomy, and half‐way between the root canal and the dentine‐cementum junction, there were found to be, on average, 27,000 tubules per mm2. Older teeth also displayed large numbers of tubules. Close to the dentine‐cementum junction, an area which may communicate with the root canal even in the presence of a retrograde root filling, an average of 13,000 tubules per mm2 were found.
Bilateral cracked teeth: a case report
Authors: CHONG B.S.
Published: September 2007

Summary. This report presents a case of undiag‐nosed, cracked, bilateral, maxillary molars. Both teeth were non‐carious and unrestored. Failure to diagnose the initial cracks resulted in further splitting, and finally complete vertical fractures. The problem of diagnosis is highlighted and the treatment of the cracked tooth to prevent its fracture is discussed.
Apical penetration by a root canal irrigant: a case report
Authors: PATTERSON C. J. W. , McLUNDIE A. C.
Published: September 2007

Summary. A case is reported in which apical penetration by a root canal irritant occurred. The clinical manifestations are described and the case management discussed.
The dentine‐removing characteristics of an ultrasonically energized K‐file
Authors: BRIGGS P. F. A. , GULABIVALA K. , STOCK C. J. R. , SETCHELL D. J.
Published: September 2007

Summary. This in vitro study evalutated the pattern of dentine removal when an ultrasonically energized file (Cavi‐Endo‐size 25 file) was applied to flat surfaces of dentine under standardized conditions. The influences of power setting, interfacial force between file and dentine, direction of file oscillation and operator‐assisted movement were examined. Impressions of the inswtrumented surfaces trevealed characteristic patterns consisting of a series of oblique creste, each one parallel to the next and separated by a constant distance along the line of contact with the file. Determination of height, width and separation of these crests with a Reflexd microscope aided objective asserssmennt.

The simplest pattern was formed when the energized file was held against the dentine (power steeing = 1; interfacial force = 30g). Increasing the power setting to 8 caused deeper troughs over the apical 5 mm. The width of the crests corresponded to the taper of the file except at the apical tip where the crests were relatively wider. However, increasing the interfacial force to 60 g reduced the efficiency of the apical part of the file.

The superimposition of operator‐induced movement greatly increased the extent of dentine removal, resulting in a tapering groove with a persistent crestal pattern. Oscillation of the file perpendicular to the dentine surface had a significantly greater influence on dentine removal, producing a deeper groove than was obtained with oscillation parallel to the surface.

The findings may be of reevance in aiding controlled root canal preparation when using the Cavi‐Endo instrument.
Capacity of anaerobic bacteria enclosed in a simulated root canal to induce inflammation
Authors: WU M.‐K. , MOORER W. R. , WESSELING P. R.
Published: September 2007

Summary. In an effort to simulate the infected dental root canal, bactria were enclosed in polyethylene tubes that were subcutaneously implanted into rats. Four different bacterial combinations, selected from nine oral species, were tested. The contents of 144 inoculated and implanted ‘root canals’ were analysed after 2 and 4 weeks of implantation. Bacteroides. Streptococcus, Actinomyces and Fusobacterium were inoculated in low numbers but dominated the mixed flora at the end of the experiment. The bacteria‐filled tubes induced inflammation of the rat tissue at the implant opening (‘foramen’). It is confirmed that mixed bacterial populations survive, show succession and develop within an enclosed environment. Such florae cause significant inflammation at the interface with the host tissues.
A one visit apicectomy technique using calcium hydroxide cement as the canal filling material combined with retrograde amalgam
Authors: CROSHER R. F. , DINSDALE R. C. W. , HOLMES A.
Published: September 2007

Summary. A prospective study was set up to evaluate a one‐visit apicectomy technique. Calcium hydroxide cement was used as the root canal filling material. The calcium hydroxide cement set rapidly and clearly revealed the position, size and outline form of the root canals at the level of resection. This facilitated preparation of the apical cavities to a depth of 3 mm. Each cavity was varnished before placement of the amalgam.

Sixty‐eight patients (93 teeth) were included in the study. Five patients (8 teeth) were lost to follow‐up. The success rate, based on clinical and radiographic examination after a minimum of 2 years, was 91.8 per cent.
The sealing ability of amalgam used as a retrograde root filling in endodontic surgery
Authors: EDMUNDS D. H. , THIRAWAT J.
Published: September 2007

Summary. A dye penetration technique was used to investigate the sealing ability of amalgam retrograde root fillings in vitro. A factorial design was employed to determine the effect of amalgam fillings of 1, 2 and 4 mm in length with and without prior filling of the canals with gutta‐percha. The results were compared with a group of teeth filled with laterally condensed gutta‐percha alone and another with laterally condensed gutta‐percha plus root resection but with no retrograde filling. It was concluded that increasing the length of the amalgam filling did not improve the seal, that prior filling of the canal did not improve the seal, that retrograde root fillings were no worse than laterally condensed gutta‐percha alone and that root resection of teeth filled with laterally condensed gutta‐percha without retrograde filling was no worse than those filled with laterally condensed gutta‐percha without root resection or retrograde root filling.
The sealing ability of materials used as retrograde root fillings in endodontic surgery
Authors: THIRAWAT J. , EDMUNDS D. H.
Published: September 2007

Summary. The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light‐cured composite resin, dentine bonding agent, and light‐cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light‐cured composite resin, light‐cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta‐percha, amalgam plus cavity varnish and EBA cement.
Comparison of curved canal shape using filing and rotational instrumentation techniques
Authors: CIUCCHI B. , CERGNEUX M. , HOLZ J.
Published: September 2007

Summary. The shaping of curved canals produced by rotational and filing instrumentation techniques was compared in 40 human molar root canals which were prepared in vitro. The tech niques used for filing were the stepback and the serial, and for rotational instrumentation were the ‘balanced force’ and an experimental technique, similar to the balanced force concept, but featuring only clockwise rotated instruments.

The results were collected from pre‐ and postoperative radiographs as well as from scanning electron microscope analysis of longitudinally ground half‐sections of the roots. Each preparation was qualitatively rated for its centering, flow, taper, apical design and wall surface appearance.

The stepback shapings consistently presented the best taper and apical stop design along with scratch‐free surfaces. The serial technique produced the best centered flow and apically deigned preparations.

The rotational techniques produced less consistent results. With the exception of some straightened specimens, the balanced force concept proved to be effective at least for the shaping of moderately curved canals. The lack of taper as well as the absence of apical stop in the balanced force shapings have been found to be more inherent in the concept of shaping than in the technique of the preparation itself. The experimental rotational preparations showed almost exactly the same shaping patterns as the balanced force ones, apart from better taper and apical design but poorer flow and visible instrument scratches. The latter two observations were related to the use of non‐tip‐smoothed instruments.
An evaluation of the retrograde apical seal using dentine bonding materials
Authors: MCDONALD N. J. , DUMSHA T. C.
Published: September 2007

Summary. The purpose of this investigation was to compare in vitro retrograde apical leakage of four dentine bonding procedures with amalgam and hot burnished gutta‐percha.

Single‐rooted teeth were prepared using a standardized stepback flare technique with recapitulation. The teeth were obturated with gutta‐percha and sealer using the lateral condensation technique and placed into a saline bath at 37°C for 30 days. The teeth were then randomly divided into seven groups of 22 teeth each. Groups I and II were apically bevelled, and dentine bonding agent with composite resin and dentine bonding agent with unfilled resin applied to the bevelled root faces, respectively. Groups III, V and VI were apically bevelled and prepared to accept a retrograde filling material of dentine bonding agent with composite resin, amalgam with cavity varnish and amalgam without cavity varnish, respective. Group IV had dentine bonding agent and unfilled resin applied to the apical third of the root, and Group VII was apically bevelled and the gutta‐percha hot burnished. The teeth were then placed into a water bath at 37°C for 30 days, stained with silver nitrate and the linear dye penetration measured.

The lowest mean leakage value was recorded in Group I, i.e. dentine bonding agent and composite resin (0.31 mm), and the highest value was observed in group VII, i.e. hot burnished gutta‐percha (4.60mm); the difference was statistically significant.
The effect of dentinal tubule orientation on the removal of smear layer by root canal Irrigants
Authors: CENGIZ T. , AKTENER B. O. , PISKIN B.
Published: September 2007

Summary. Fifteen anterior teeth and 15 artificial canals obtained from five molar teeth were used in this study. The artificial and natural canals were instrumented with K‐files and then divided into three groups. The first group was irrigated with 20 ml saline, the second with 20 ml EDTA, and the third with 10ml EDTA followed by 10ml NaOCl solution. Following this experimental procedure, all canals were split and examined in a scanning electron microscope. The results showed that the smear layers in both artificial and natural canals were similar in appearance and responded similarly to all irrigation solutions. In addition, in the artificial canals, it was observed that the dentinal tubule orientation had no detectabie effect on formation and removal of smear layers.
Clinical application of glass ionomer cements in endodontics: case reports
Authors: STEWART G. G.
Published: September 2007

Summary. The usefulness of glass ionomer cements in endodontics is illustrated by selected case histories. The situations varied from root repair to root end filling. The use of regular glass ionomer cement and a reinforced version are presented. In addition, the preparation of a modified glass ionomer cement, that could be used alone, or with gutta‐percha, for root canal obturation is described.
Repeated removal of a temporary dressing as an attention‐seeking device
Authors: TREASURE E. T. , TREASURE P.
Published: September 2007

Summary. A case is reported in which endodontic treatment of an upper central incisor was delayed by repeated failure of the temporary dressing. The cause of failure was not identified until a sewing needle was found lodged in the canal. The patient had repeatedly removed the dressing, possibly in an effort to gain attention.
A comparison of subcutaneous connective tissue responses among three different formulations of gutta‐percha used in thermatic techniques
Authors: LEONARDO M. R. , UTRILLA L. S. , ROTHIER A. , LEONARDO R. T. , CONSOLARO A.
Published: September 2007

Summary. A study of the subcutaneous connective tissue response of 24 white rats to three different formulations of gutta‐percha was undertaken. The prepared specimens were examined under the light microscope after intervals of 7, 21, 60 and 120 days.

The results showed identical tissue responses after the initial period of 7days. However, after 120 days the gutta‐percha supplied with the Ultrafil system presented mature granulation tissue with neither oedema nor vascular congestion, in contrast to the responses observed with the McSpadden and Obtura formulations.
A review of calcium hydroxide
Authors: FOREMAN P. C. , BARNES I. E.
Published: September 2007

Summary. Calcium hydroxide is a material which has been used for a variety of purposes since its introduction into dentistry in the early part of the twentieth century. In its pure form, the substance has a high pH, and its dental use relates chiefly to its ability to stimulate mineralization, and also to its antibacterial properties. A range of products has been formulated with different therapeutic actions, the effects of which are partially dependent upon the tissue to which they are applied. The material is reviewed under the following general headings: biochemical actions; dental formulation; uses.
An in vitro study to compare impact fracture resistance of intact root‐treated teeth
Authors: McDONALD A. V. , KING P. A. , SETCHELL D. J.
Published: September 2007

Summary. The aim of this in vitro study was to determine the effect on impact fracture resistance of three methods for restoration of root‐treated lower incisor teeth with otherwise intact natural crowns. In a control group (Group I) laterally condensed gutta‐percha filled the entire root canal, whereas part of the root filling was removed to enable insertion of a 1 mm diameter post in the other two groups. Stainless steel posts were placed in Group II and experimenral carbon fibre reinforced carbon (CFRC) in Group III. A composite resin luting agent was used to lute the posts, and standardized composite resin restorations were placed in each access cavity.

Fifteen specimens of each group were tested to failure with a single impact force applied at 90 degrees to the mid‐point inciso‐cervically on the labial surface. The peak force, peak energy, and first peak total energy required to fracture each specimen were recorded. The results showed no significant difference between the three groups, nor was a difference in the mode or site of fracture observed.

The results suggested that there is no advantage from the point of view of fracture mechanics in ‘restoring’ intact root‐treated teeth with either stainless steel or carbon fibre reinforced carbon rods.
Detection of bacteria in histological sections of the dental pulp
Authors: WATTS A. , PATERSON R. C.
Published: September 2007

Summary. A series of deep cavities with and without traumatic pulpal exposures were prepared in the maxillary molars of albino rats. They were left untreasted for various time intervals before killing.

Demineralized sections were prepared in a mesiodistral plane and stained to demonstrate the presence that were grossly contaminated, bacteria were detected in the majority of sections. In the roor canaks and periapical tissues, bacteria were detected in only a minority of sections.

It is considered that serial sections stained to demonstrate bacteria are necessary for the detection of bacteria that the present in only small numbers in the tissue. The demonstration of small numbers of micro‐organisms in specific zones of the pulp remains problematic. Failure to detect stained bacteria in histological sections is not absolute proof of their absence.
Assessment of leakage in the restored pulp chamber of endodontically treated multirooted teeth
Authors: SAUNDERS W. P. , SAUNDERS E. M.
Published: September 2007

Summary. The leakage associated with restorative materials placed within the pulp chamber of maxiliary and mandibular molars was studied in vitro. The root canals and pulp chambers of 69 extracted teeth were prepared chemomechanically and scaled with gutta‐percha and Tubliseal using cold lateral condensation. The teeth were divided into five groups. Gutta‐percha was removed from the pulp chambers of three of the groups of 15 teeth and filled with one of three materials, a glass ionomer cement, a cermet cement or an amalgam. The guttapercha was removed from the pulp chamber in the fourth group of nine teeth, which were left unfilled. The gutta‐percha in the pulp chambers of the fifth group of teeth was left intact.

The teeth were suspended in Indian ink, thermocycied for 24 hours and stored for a further 48 hours at 37°C. They were then demineralized and cleared and the degree of coronal leakage was assessed. Those teeth with no filling in the pulp chamber showed extensive leakage. The gutta‐percha‐filled group demonstrated greater leakage than did the groups in which other restorative materials had been employed (P<0.01). No significant differences in leakage occurred between the other groups (P>0.05). It is recommended that the pulp chamber of molars should be restored with a filling material following root canal treatment.
Root canal anatomy of mandibular second molars
Authors: MANNING S. A.
Published: September 2007

Summary. The root canal anatomy of 19 mandibular second molars with C‐shaped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apicaf foramen was most commonly situated away from the apex, and apical deltas were found in 16 of the 19 roots. The C‐shaped canals were found more frequently in Asians than in other racial groups (P < 0.02).

The formation of C‐shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C‐shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems.
Stimulation of the growth ofStreptococcus sanguis (NCTC 7864) by zinc in vitro
Authors: MERYON S. D. , JOHNSON S. G.
Published: September 2007

Summary. Zinc, which is present in many materials used in dentistry, including restorative and endodontic materials and mouthwashes, is reputedly bactericidal. However, the addition of this element at concentrations in the range 10–50 ppm to cultures ofStreptococcus sanguis (NCTC 7864) stimulated the growth of the micro‐organism relative to that of controls. A second antibacterial element, namely fluoride, reduced growth. Similar results were obtained whether the organism was grown aerobically or anaerobically. In view of the susceptibility of some organisms to zinc, the results of this study may help to explain conflicting reports in the literature; the results will vary depending on which organism is predominant.
A quantitative microleakage study on a new retrograde filling technique
Authors: WU M.‐K. , KEAN S. D. , KERSTEN H. W.
Published: September 2007

Summary. An in vitro endodontic leakage model was used to compare the sealing ability of conventional retrograde amalgam fillings with a new retrograde filling technique by measuring dye leakage quantitatively.

The new technique consisted of retrograde preparation of the root canal using the Endocursor1, an endodontic handpiece. The canal was then filled with sealer and injection‐moulded gutta‐percha, using either the Hygenic Ultrafil2 system or the Unitek Obtura3 method. In both cases the guttapercha was vertically condensed and subsequently cold‐burnished.

The two experimental groups and the amalgam group each consisted of 20 extracted human canine teeth and lower premolars. The results were analysed statistically by ANOVA and a Student‐Newman‐Keuls multiple comparison test. After 1 week at 37°C, very little leakage was observed in the amalgam and gutta‐percha groups. After a second week, during which leakage was enhanced by gas pressure, leakage in the amalgam group was significantly greater than that in the gutta‐percha groups (P 0.01). There were no significant differences between the two experimental gutta‐percha groups. It is concluded that the new retrograde filling technique causes less leakage than the conventional amalgam retrograde filling technique in an in vitro model.
A standardized technique for linear dye leakage studies: immediate versus delayed immersion times
Authors: POLLARD B. K. , WELLER R. N. , KULILD J. C.
Published: September 2007

Summary. A dye leakage study was performed in vitro to compare the extent of leakage into root canals obturated with gutta‐percha following immediate versus delayed immersion in Indian ink. Sixty extracted human teeth with single canals were instrumented and obturated with gutta‐percha and sealer. Each group of 20 teeth was then immersed in the ink either immediately after obturation or after a delay of 1 or 7 days. After 7 days in Indian ink, the teeth were rendered transparent by clearing, and the linear extent of ink penetration was measured with a stereomicroscope. Complete leakage was observed in the two positive control teeth, and no leakage was evident in the two negative controls. Statistical analysis of the results indicated that there was no significant difference in leakage between the three experimental groups.
In vivo findings associated with heat generation during thermomechanical compactionof gutta‐percha. Part II. Histological response to temperature elevation on the external surface of the root
Authors: SAUNDERS E. M.
Published: September 2007

Summary. An in bim investigation is described and a histologiesl evaluation made of the effect of canal obturation by thermomechanical compaction of gutta‐percha and sealer on the cementum on the lateral surface of the root and adjacent periodontal membrane and alveolar bone of the ferret canine after rime intervals of 24 hours, 20 days and 40 days. These tissue reactions were compared with those in the roots of control teeth filled by lateral condensation of cold gutta‐percha and sealer. latrogenk‐damage was apparent in a minority of the experimental specimens 20 and 40 days after obturation.
The effect of pulp capping and pulpotomy on hard tissue bridges of contaminated pulps
Authors: HEIDE S.
Published: September 2007

Summary. The pulp and dentine of permanent incisors in 13 young monkeys were exposed by grinding. The pulpat perforations were treated by partial pulpotomy with a tungsten carbide fissure bur after exposure for 4, 48, or 168 hours in nine animals, and by direct pulp capping after exposure for 4 or 48 hours in the remaining four animals. After haemostasis, the pulpal wounds were covered with calcium hydroxide (Dycal), followed by conventional amalgam (Revalloy). Initial and subsequent formation of hard tissue bridges over the wounds was studied by conventional histology after 1–6 months. Screening showed three categories of initial bridging development, differing in nature and rate of formation. A significant difference in the distribution of the two main categories was found between the two methods of treatment(P<0.02). A similar difference was observed when partial pulpotomy was performed after 168 hours compared with that performed after 4 hours (P=0.055). No relationship was found between the initial bridging category and the eventual development of complete dentine bridges.
Perspectives on periradicular healin using Sealapex: a case report
Authors: GUTMANN J. L. , FAVA L. R. G.
Published: September 2007

Summary. The use of the calcium hydroxide‐containing root canal sealer, Sealapex, has been questioned regarding its predisposition to solubility and subsequent effect on the root canal seal and periradicular healing. This case report demonstrates, radiographically, dissolution of excess sealer in the periradicular tissues with subsequent osseous repair which was similar to healing in periradicular tissues where there was no extruded sealer.
Endodontics in the UK 1990: an overview
Authors: STOCK C. J. R.
Published: September 2007

Summary. The first workshop on endodontics, in 1978, pointed out that the standard of endodontics in the United Kingdom was poor. The British Endodontic Society has subsequently attempted to improve the remuneration in the NHS by conducting and publishing a survey, and also establishing guidelines for minimum acceptable standards. Despite this, in the author's opinion, there has been no improvement. However, four ways of raising the standards of endodontics are proposed.
Undergraduate endodontic teaching at the London Hospital Dental Institute
Authors: AHLBERG K. F.
Published: September 2007

Summary. Integration, whole patient care and small group teaching are concepts which set the pattern for undergraduate teaching at ‘The London’. This system promotes co‐operation between disciplines, enables students to see the basic teaching in a wider clinical context, activates the learning process and gives students an opportunity to learn responsibility by running their own ‘mini‐practices’. Unfortunately, the system also has some undesirable effects, which are discussed with special reference to the teaching of endodontics.
The curriculum in endodontology at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands
Authors: WESSELINK P. R.
Published: September 2007

Summary. At the Academic Centre for Dentistry, Amsterdam (ACTA) clinical endodontics is taught and practised in a general clinic supervised by general dental practitioner instructors; they are continuously trained and supported by the endodontic staff, who ire members of the Department of Cariology and Endodontoiogy. The scientific basis of endodontology and the theory of clinical endodontic procedures are taught by the endodontic staff, primarily by using a textbook, a clinical manual, videotapes and a computer program, all accompanied by detailed instructional objectives. During their preclinical training, which allows 63 hours for practising procedures and performing several clinical tests, the students are taught one basic technique to prepare and fill root canals and to restore endodontically treated teeth. This technique, accompanied by clearly outlined criteria, is also used in the patient clinic.

In the experience of the staff, who are limited to endodontology, the use of manuals, audiovisual aids and instructional objectives has been very beneficial, and the student's assessment of the endodontology course was, in general, very favourable. Although the clinical results are quite good, the endodontic staff feel that there is still some room for improvement of the teaching. Finally, an elective period has recently been introduced.