bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibacterial activity of dental restorative materials
Authors: TOBIAS R. S. , BROWNE R. M. , WILSON C. A.
Published: September 2007

Summary. The antibacterial activity of several dental materials (zinc oxide‐eugenol cement, Kalzinol, zinc phosphate cement, Silicap, Super Syntrex, Aspa, Chembond, Chemfil and Aquacem) was investigated in vitro against six micro‐organisms isolated from ferret plaque (Moraxella spp., Escherichia coli, Corynebacterium spp., Actinomyces viscosus, Enterococcus, Streptococcus sanguis). All freshly mixed materials showed some degree of antibacterial activity, though the effects varied between micro‐organisms. A ranking order was obtained for each material, and each material exhibited some reduction of effect after 72 hours’ culture.

There was a substantial reduction in bactericidal properties of all materials 24 hours and 7 days after setting, this reduction being least for zinc oxide‐eugenol cement. The possible relationship between the antibacterial activity of the materials, bacterial contamination of the cavity and the pulpal response is discussed.
Endodontic management of molars with developmental anomalies
Authors: FRIEDMAN S. , STABHOLZ A. , ROTSTEIN I.
Published: September 2007

Summary. Rare reports of endodontic therapy in fused permanet molars appear in the literature, and these indicate the complexity of such cases. Three further cases are reported in this paper, establishing a conclusion of clinical value; all the root canals should be expected to emerge from one chamber, comprising one root canal system. This finding dismisses any attempts of ‘partial’ therapy in cases of posterior fusion. The variability in root canal systems in fused teeth makes it difficult to predict their configuration. Endodontic treatment of fused teeth calls for special efforts directed towards realizing and successfully managing their complex root canal systems.
The efficiency of irrigants in removing root canal debris when used with an ultrasonic preparation technique
Authors: GRIFFITHS BRIGITTE M. , STOCK C. J. R.
Published: September 2007

Summary. Three types of irrigant, 2.6 per cent sodium hypochlorite, water and Solvidont were compared for their ability to remove debris during root canal preparation with ultrasonically operated K files. Twenty‐seven freshly extracted human teeth were divided into three groups, and each group prepared using one of the irrigants. The teeth were sectioned longitudinally, stained and photographed for assessment by a ranking system. Canals prepared with sodium hypochlorite were found to have significantly less debris remaining than those prepared with water or Solvidont. No significant difference was found between preparations with water and Solvidont.
Problems with the endodonic—orthodontic management of fractured teeth
Authors: FEIGLIN B.
Published: September 2007

Summary. Some of the problems that can occur in the orthodontic extrusion of subgingivally fractured teeth are discussed. It is emphasized that, with proper care and attention to detail, these fractured teeth can be successful in the long term.
An evaluation of the Endometric Probe in root canal length estimation
Authors: DUMMER P. M. H. , LEWIS J. M.
Published: September 2007

Summary. The purpose of this study was to evaluate the effectiveness of the Endometric Probe in the determination of root canal length in vitro. Using periapical radiographs, the lengths of root canals in 36 extracted teeth were assessed with the aid of a K‐file and an Endometric Probe. Both instruments were sealed, in turn, within each tooth some distance short of the true canal length. The distance between the tip of the instrument and a distance 1 mm short of the actual apex of the tooth was estimated from the radiographs. This distance was then added to the known length of the instrument in the canal to give an estimated canal length. Finally, the true length of each canal was determined by direct measurement using a reproducible method. The differences between the true and estimated canal lengths were then calculated and correlated with the type of instrument used. The results showed that, under the test conditions, the Endometric Probe was more reliable for root canal length estimation than the K‐file.
Effects of endodontic instrumentation using a macroradiographic subtraction technique: a preliminary investigation
Authors: WOOKEY C. P.
Published: September 2007

Summary. Microfocus radiography affords a means of examining the detailed effects of instrumentation on root canal systems of extracted teeth. A series of magnified radiographs of the root before and after instrumentation was obtained using an industrial microfocus unit and fine grain film. In this way, magnification with good resolution, impossible by conventional dental radiography, was obtained. This method gave good definition of the border between dentine and pulp so that changes due to instrumentation could be detected. A subtrction technique was applied to radiographs of nine teeth before and after instrumentation to compare the change in the pulpal outline. The method entailed accurate location and superimposition of macroradiographs taken befor and after preparation. Changes in actual canal width could be measured to ±0.1 mm. The technique demonstrated that some canal walls had not been altered while other walls had been overinstrumented. Straightening and transportation of the canal were also observed on some specimens. It was concluded that macorradiography and the subtraction technique were suitable for the quantitative investigation of the change of canal shape from instrumentation.
Further studies on the exposed germ‐free dental pulp
Authors: PATERSON R. C. , WATTS A.
Published: September 2007

Summary. Refinement of techniques has made available much larger numbers of teeth for studying the response of the exposed pulp in germ‐free rats. At shorter time intervals the inflammatory response, in the absence of bacteria, was limited to the presence of scattered cells lying in the debris at the wound surface. Inflammatory infiltration of pulp tissue was not observed, even where large exposures were present. At longer time intervals some pulp necrosis was observed. This was considered to be the result of food packing into the open pulp chambers. The previous observation of a high incidence of dentine bridge formation in germ‐free animals was confirmed.
Further studies on heat generation during obturation techniques involving thermally softened gutta‐percha
Authors: HARDIE ELIZABETH M.
Published: September 2007

Summary. A study in vitro investigated the heat generated at the root face of human single‐rooted canine teeth during the use of thermally softened gutta‐percha root‐filling techniques. The temperature rise was recorded at two points on the outer surface of each tooth using thermocouples linked to a chart recorder. Four groups of specimens were used in the study. In the first group, the teeth were root filled using a plugger at a rotational speed of 8000 rev/minute. In the second group, the teeth were obturated with a plugger of the same design but at a rotational speed of 16,000 rev/minute. The third group was root filled with a combination of lateral condensation of gutta‐percha and mechanical compaction, and in the final group, filling was carried out using the Unitek Obtura system. The results showed that significant temperature rises occurred in the four groups and that these rises were greater at the central point than apically. An increase in the rotational speed of compaction caused an increased temperature rise at the apical region. The heat generated by the injection of thermally softened gutta‐percha was slower to dissipate than with the other techniques. The results of these investigations would indicate that the temperature rises generated during the use of thermally softened gutta‐percha in endodontic obturation lie within the range likely to cause tissue damage.
The shape and location of mandibular premolar access openings
Authors: WILCOX L. R. , WALTON R. E.
Published: September 2007

Summary. Access openings for mandibular premolars have invariably been shown in textbook diagrams to be wide ovals centered over the central groove. This study examined 100 mandibular premolars to evaluate this access outline. Pulp dimensions and locations were determined from radiographs in order to evaluate the relationship of the pulp canal to landmarks on the occlusal surface of the tooth. The results showed that in 96 per cent of teeth the pulp was narrower mesiodistally than 1.4 mm, and in the majority of premolars the pulp lay under the lingual triangular ridge of the buccal cusp. Therefore, the entire pulp would usually be accessible by a narrow opening with a lingual termination at the central groove.
Endodontic irrigation—a comparison of endosonic and syringe delivery systems
Authors: TEPLITSKY P. E. , CHENAIL B. L. , MACK B. , MACHNEE CORRINE H.
Published: September 2007

Summary. This study compared syringe irrigation with endosonic‐facilitated irrigation. Two experiments, conducted on acrylic models and extracted natural human teeth, tested both the degree of apical penetration and the flushing potential of irrigant in canals prepared to different sizes. Radio‐opaque dyes of different viscosities were used to monitor radiographically irrigant delivery or dye removal. Results indicated that endosanics was significantly superior to syringe irrigation alone, particularly in canals prepared apically to a diameter of 0.3 mm or less without coronal flaring.
Perspectives on root canal obturation with thermoplasticized injectable gutta‐percha
Authors: GUTMANN J. L. , RAKUSIN H.
Published: September 2007

Summary. Perspectives on the clinical usage of a thermoplastic injection delivery system for guttapercha are presented. Areas which have been identified as problems in the clinical use of the technique and management of the system are highlighted. succinct guidelines for effective usage are presented along with cases typifying clinical achievement.
Evaluation of three thermoplasticized gutta‐percha filling techniques using a leakage modelin vitro
Authors: KERSTEN H. W.
Published: September 2007

Summary. In an experimetal model the leakge of three endodontic filling techniques using the thermoplasticity of gutt‐percha, was compared with the leakge occurring in canals filled by lateral condensation.

Forty‐six blocks of artificial dentine, comprised of hydroxyapatite and polyethylene, containing standardized curved and prepared ‘root canals’, were mounted in open‐ended tubes. Five groups of eight canals each were obturated by: (i) a combination of lateral condensation and thermomechanical compaction (hybrid technique), (ii) by lateral condensation with the use of a heated spreader (Endotec), (iii) by injection of low‐temperature thermoplasticized gutta‐percha, (iv) by conventional lateral condensation performed by an experienced operator, and (v) by lateral condesation performed by an inexperienced operator. Two blocks with canals left open served as positive controls. Four blocks without canals served as negative controls. At the coronal end of the canals the tubes were filled with 0.5 per cent butyric acid and 0.1 per cent valeric acid in water. The apical reservoir was filled with 0.1 per cent valeric acid. The tubes were closed with rubber membrace stoppers at both ends. The butyric acid was the material to leak, the valerate served and an internal standard. Six and 11 days after obutration, samples which were drawn from the apical reservoir, were acidified and injected into a gas chromatograph for butyric and valeric acid concentration analysis. Six day samples did not show a statistical difference in leakage among groups. Eleven‐day samples, after 5 days of forced leakage through elevated pressure at hte coronal reservoir did, however, show a statistical difference using one‐way analysis of variance. The Student‐Keuls multiple comparison test revealed that the group filled with the use of the Endotec had significantly less leakage than any of the other groups. Nodifference was observed in leakage between the tow lateral conddensation group. Correspondence: Dr H. W. Kersten, Academic Centre for Dentistry Amsterdam (ACTA), Department of Cariology and Endodontology, Louwesweg 1,1066 EA Amsterdam, The Netherlands.
Three canals in the mesial root of mandibular first permanent molars: a clinical study
Authors: FABRA‐CAMPOS H.
Published: September 2007

Summary. Traditional teaching of the anatomy of root canals in different teeth can lead clinicians into the misguided belief that a predetermined number of root canals is always present in any given tooth. A new understanding of the root canal system has enabled the location of additional canals.

Results of the clinical study of 760 first mandibular molars, showed that 20 (2.6 per cent) had three canals in the mesial root. Of these 20 teeth, 13 (65 per cent) had an intermediate canal which joined the mesiobuccal canal in the apical third. In six cases (30 per cent) it joined the mesiolingual canal in the same area. In only one case did the intermediate or third canal retain its individual nature and end in an independent foramen.
An in vitro method for comparing the effcts of different root canal preparation techniques on the shape of curved root canals
Authors: TANG M.P.F. , STOCK C.J.R.
Published: September 2007

Summary. This study introduced an in vitro model which was designed to observe the effects of instrumentation on the shape of curved root canals. The model may be accurately rotated through 90° allowing reproducible radiographs to be taken from two different angles. The root canals were filled with a radiopaque contrast medium before radiographs were taken. Two‐dimensional evaluation of the shape of the root canals, before and after preparation was made on enlarged photographic prints obtained from the radiographs. A custom‐made grid was used as a guide for measurement and accurate transfer from the pre‐ to postpreparation prints. Reproducibility of measurement was within 4 per cent. This method is feasible for quantitative comparison of the effect of instrumentation on the shape of root canals.
Odontiatrogenic tooth fracture
Authors: SCHWEITZER J. L. , GUTMANN J. L. , BLISS R. Q.
Published: September 2007

Summary. While the awareness of vertical tooth fractures, whether incomplete or complete, is increasing, sufficient attention has not been paid to the manner in which the dentist may contribute id the occurrence of these fractures. This paper focuses on the most likely areas in which the practitioner can either misdiagnose the presence of a fractured tooth or where dental procedures contribute to fracture of the tooth structure. For this type of fracture the authors propose the term ‘odontiatrogenic tooth fracture’.
An investigation of possible iatrogenic damage caused by metal rubber dam clamps
Authors: JEFFREY I. W. M. , WOOLFORD M. J.
Published: September 2007

Summary. Rubber dam may be held in place over a tooth by metal clamps. It has been shown that a mismatch of contact between the clamp gripping edge and the tooth surface may be reduced to a point contact, thereby concentrating the gripping force generated by the bow of the clamp. Experiments were conducted to measure the force. Clinically realistic loading of the tooth surface by sections of the gripping edge of clamps was carried out using special apparatus. Examination by scanning electron microscopy showed that iatrogenic damage to the tooth could occur. Therefore a plea is made for clamps to be redesigned to reduce any harm.
Particles and molecules in endodontic leakage
Authors: KERSTEN H. W. , MOORER W. R.
Published: September 2007

Summary. It is assumed that above a critical level, microleakage causes periapical disease and jeopar‐dizes periapical tissue repair. The purpose of this investigation was first to find out to what degree obturation prevents leakage of bacteria‐sized particles or large protein molecules, and second it leakage of the commonly used dye methylene blue is comparable with that of a small bacterial metabolic product of similar molecular size.

Sections, 9 mm long, obtained from 46 extracted human incisor roots had their root canals prepared in a standardized manner and obturated in four experimental ways using gutta‐percha. The root sections were mounted in the middle of tubes that were closed at both ends with rubber membrane stoppers, which permitted sampling from the apical reservoir. The coronal reservoir was filled with a solution of 1 mg/ml latex beads, 4 μg/ml endotoxin, 0.5 per cent butyric acid, 0.1 per cent valeric acid and 0.1 per cent methylene blue in water. After 1 and 2 weeks, samples were taken from the apical reservoir and tested tor the presence of latex beads by phase‐contrast microscopy, for endotoxin with a limulus lysate test, (or butyric acid with gas‐chromatography and for methylene blue with spec‐trophotometric analysis. Leakage of bacteria‐sized particles and large‐sized protein molecules could be prevented only when both sealer and pressure were used in obturating root canals with gutta‐percha. Leakage of butyric acid proved to be comparable with leakage of methylene blue; microleakage of these small molecules could not be prevented in this study whatever method of filling was used.
The effect of variation in thermomechanical compaction techniques upon the quality of the apical seal
Authors: SAUNDERS E.M.
Published: September 2007

Summary. The purpose of the present study was to assess the effect of compactor design, alterations in rotational speed and modification to the basic technique of thermomechanical compaction on the quality of the apical seal produced by gutta‐percha and sealer cement. The integrity of the apical seal achieved using two different configurations of compactor, rotational speeds of 8000 and 16,000 rev/ minute and a hybrid technique which combined thermomechanical compaction with lateral condensation were compared with conventional lateral condensation. The same brand of gutta‐percha and type of sealer were used throughout the investigation.

A cleared tooth technique that allowed the three‐dimensional assessment of Indian ink leakage was employed. Instrument fracture, a problem experienced in some other investigations, did not occur with either design of compactor used. Apical dye leakage was found to be a relatively frequent occurrence with each variation in obturation technique studied, including that of lateral condensation of cold gutta‐percha and sealer. The results showed no significant difference in the mean degree of leakage for each of the groups or in the proportion of specimens that showed leakage (P > 0.1).

The advantages of the hybrid method of root canal obturation were discussed.
In vitro comparison of the cytotoxicity of twelve endodontic materials using a new technique
Authors: MERYON S. D. , BROOK A. M.
Published: September 2007

Summary. An in vitro method for the cytotoxicity testing of endodontic materials is described which aims to simulate the clinical situation. Materials can be tested in the presence or absence of a compacted layer of dentine chips mimicking the periapical dentine plug. A total of twelve materials were tested. In the absence of dentine, Kloroperka, Biocalex, Diaket and Endomethasone were slightly cytotoxic; AH26 with and without silver, Sealapex, Tubliseal and Kerr's pulp canal sealer were moderately cytotoxic, while Forfenan, Spad and Kri paste were strongly cytotoxic. In the presence of dentine the cytotoxicity of these materials was considerably reduced, with the exception of Endomethasone, Forfenan, Spad and Kri paste. The method provides a satisfactory alternative to implantation testing and is an inexpensive and reproducible test system in which dentine can be incorporated.
The retrieval of silver cones using different techniques
Authors: HÜLSMANN M.
Published: September 2007

Summary. Three different techniques of silver cone retrieval were investigated in 41 teeth containing 91 silver cones. The techniques used for retrieval were as follows:

hand instrumentation with files, spoon excavators and forceps;

the automated Canal‐Finder‐System;

ultrasonic devices.

In all teeth, these techniques were used in the same sequence, starting with hand instrumentation, followed by the Canal‐Finder‐System, and ending with ultrasonic devices. Fifty‐two of the 91 cones (57 per cent) could be removed with hand instruments. Of the remaining 39 cones, 19 were removed after using the Canal‐Finder‐System. An additional 10 cones could be removed after the use of ultrasonics. Two cones could only be bypassed by the Canal‐Finder‐System but were not removed with any of the techniques investigated in this study. Eight silver cones (9 per cent) could neither be bypassed nor removed. It was concluded that silver cone retrieval in more than half the cases could be performed easily with hand instruments, particularly spoon excavators. The automated Canal‐Finder‐System and ultrasonics proved to be helpful devices in many difficult cases, but did not guarantee success in every case.
The assessment of pulpal vitality
Authors: ROWE A. H. R. , FORD T. R. PITT
Published: September 2007

Summary. This is a review of methods of assessing dental pulp vitality in order to assist the clinician in diagnosis and treatment planning. It covers the patient's history, clinical examination, assessment of radiographs, thermal tests, electrical tests, test cavities, use of anaesthesia, and the recent application of laser Doppler flowmetry.
Characterization of two types of human oral fibroblast with a potential application to cellular toxicity studies: tooth pulp fibroblasts and buccal mucosa fibroblasts
Authors: ARENHOLT‐BINDSLEV D. , BLEEG H.
Published: September 2007

Summary. Cultures of human oral buccal mucosa fibroblasts and human tooth pulp fibroblasts were established and grown under standard routine conditions. The biological characteristics of cell proliferation, growth pattern, cell morphology and enzyme release (lactate dehydrogenase and acid phosphatase) were studied.

Under the same standard in vitro conditions the two cell types demonstrated different growth patterns and different levels of enzyme activity.

It is suggested that differences in biological characteristics should be considered when selecting appropriate cells for lexicological studies of dental materials.
The microbial flora from root canals and periodontal pockets of non‐vital teeth associated with advanced periodontitis
Authors: KOBAYASHI T. , HAYASHI A. , YOSHIKAWA R. , OOKUDA K. , HARA K.
Published: September 2007

Summary. Microflora from root canals and periodontal pockets of periodontally affected were compared in order to elucidate the as yet unknown relationship between pulpal and periodontal disease.

Caries‐free teeth affected with advanced periodontitis and diagnosed as clinically dead by electric pulp testing were selected. The root canals and periodontal pockets were sampled, and the bacterial flora examined by both culture and interference microscopy. The results indicated that the aerobe/anaerobe ratio in the periodontal pocket was 0.23, while it was 0.0022 in the root canal, the large predominance of morphotypes in the two sites. Results of anaerobic culture demonstrated a significantly higher rate of detection of facultative Streptococcus bacteria in the periodontal pocket than in the root canal.

The predominant bacterial species common to both regions were Streptococcus, Peptostreptococcus, Eubacterium. Bacteroides, and Fusobacterium for obligate anaerobes. As for facultative anaerobes, ActinomycesStreptococcus were detected predominantly in the periodontal pocket. The occurrence of micro‐organisms common to both sites in this study suggests that the periodontal pocket may be a possible source of root canal infections.
Microbiological evaluation of clindamycin as a root canal dressing in teeth with apical periodontitis
Authors: MOLANDER A. , REIT C. , DAHLÉN G.
Published: September 2007

Summary. The present investigation was designed to study the effect of clindamycin on root canal infection when placed as an intracanal dressing. Twenty‐five teeth with necrotic pulps and periapical radiolucencies were included. Following initial bacteriological sampling and routine instrumentation, clindamycin powder mixed to a paste with saline was applied for 14 days. The presence or absence of bacteria was determined in samples taken immediately after removal of the dressing, and after a period of 7 days during which the canals were filled with sampling fluid. Bacteria were recovered from four and six teeth respectively. The results indicated that clindamycin offered no advantage over conventional root canal dressings, such as calcium hydroxide, and it is therefore not recommended for use in routine endodontic therapy.
In vivo findings associated with heat generation during thermomechanical compaction of gutta‐percha. Part I. Temperature levels at the external surface of the root
Authors: SAUNDERS E. M.
Published: September 2007

Summary. Temperature elevations of 10°C above body temperature, of duration 1 minute, may be sufficient to cause bone tissue injury. Temperature rises on the root surface in excess of 10°C have been shown in studies in vitro of thermoplasticized gutta‐percha root filling techniques. To determine whether results in vitro at room temperature could be extrapolated to conditions in vivo, temperature elevations were recorded at the mid‐point on the root surface of the canine tooth in the ferret during thermomechanical compaction of gutta‐percha. The time taken for the temperature to return to normal was also measured. There was no statistically significant difference between temperature elevations recorded in vitro and those measured in vivo, A linear extrapolation may therefore be made from results recorded at room temperature.

Temperature elevations dissipated more rapidly in vivo than in vitro; this may be due to the cooling effect of the microvasculature of the periodontal membrane.
Pulpal response to two semihydrous glass ionomer luting cements
Authors: TOBIAS R. S. , BROWNE R. M. , PLANT C. G. , WILLIAMSf J. A. , RIPPIN J. W.
Published: September 2007

Summary. This study compared the pulpal responses to two innovative semihydrous glass ionomer luting cements (STA1 and ZIN2) with those previously obtained for a conventional anhydrous giass ionomer luting cement, Aquacem3. ZIN contained zinc oxide in the formulation. The study was conducted according to the BSI (1989) recommendations for testing restorative materials in vivo. ZIN was associated with minimal pulpal changes and mtcrobial microieakage, and differed little from the control material, Kalzinol4. The pulpal response to STA was similar to that observed for Aquacem, but was associated with less microbial microieakage. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The closer that bacteria were to the pulp, the more severe was the ensuing inflammation.
The antimicrobial effect of calcium hydroxide as a short‐term intracanal dressing
Authors: SJöGREN U. , FIGDOR D. , SPÅNGBERG L. , SUNDQVIST G.
Published: September 2007

Summary. The antibacterial effect of calcium hydroxide as a short‐term intracanal dressing was clinically evaluated by applying the medicament for 10 minutes or 7 days in root canals of teeth with periapical lesions. The results showed that the 7‐day dressing efficiently eliminated bacteria which survived biomechanical instrumentation of the canal, while the 10‐minute application was ineffective.
Specialization in endodontics
Authors: MARTIN D. M.
Published: September 2007

Summary. The dental profession within the UK is currently reviewing the desirability of recognition of practice‐based specialties and the establishment of specialist registers in various disciplines, including endodontics. In order to merit consideration for specialty status, in any discipline there must be an increase in the level of theoretical knowledge, and in the range and complexity of clinical procedures beyond the bask level of training. There must be an identified public need extending beyond the provisions of the general dental services for the particular skills of the practice‐based specialist, who would also complement the consultant services, which have a limited capacity to provide the level of treatment demanded.

Acceptance of the principle of specialist practice implies a belief that this will enhance the development of the profession, improve academic and clinical standards and provide a higher‐quality and more widely available service to the public. The case for the specialist endodontist is argued, as is the importance of establishing appropriate academic and clinical training programmes to equip individuals with the requisite knowledge and skills. Academic institutions must develop imaginative and innovative courses to provide such education within the profession.
Setting up an MSc programme in endodontics
Authors: GULABIVALA K.
Published: September 2007

Summary. The course has been designed to provide a suitable foundation for academic and genera] practice careers. Emphasis has been placed on developing diagnostic and practical skills. Students are encouraged to review their clinical practice critically in the light of recent advances in knowledge. The course begins with an intensive period of lectures and seminars covering general aspects of endodomics, and is generously supplemented by practical demonstrations and classes on a variety of procedures performed on laboratory models. The course continues with lectures and seminars designed to stimulate group discussion. These are complemented by supervised clinical sessions encompassing assessment, planning and treatment of a comprehensive range of conventional and surgical endodontic problems. The syllabus includes relevant basic sciences, pathology, differential diagnosis, pharmacology and therapeutics. The biological basis for endodontics is stressed and covers the following: maintenance of pulp vitality; effects of pulp capping, pulpotomy and pulpectomy; the management and treatment of traumatic injuries to teeth; the management of medically compromised patients; the effect of various methods of instrumentation of root canals; radiology; restorative treatment of the endodontically treated tooth; the interface between endodontics and periodontics, prosthetics or orthodontics. Each student is required to undertake a research project and write a report.
A method for the construction of simulated root canals in clear resin blocks
Authors: DUMMER P. M. H. , ALODEH M. H. A. , AL‐OMARI M. A. O.
Published: September 2007

Summary. A method for the construction of simulated root canals in clear resin blocks is described. The canals are inexpensive, simple to produce and are of high enough quality for use in both undergraduate and continuing education. With minor modifications, the canals can also be used for research, particularly during the assessment of instruments and preparation techniques.
Tissue responses assessed by intramuscular implantation
Authors: REID R. J. , WILSON D. F. , CHAU K. K. , HEITHERSAY G. S. , HEIJKOOP P. S.
Published: September 2007

Freshly mixed polymerized Hydron root canal filling material, fully set AH26 and Teflon were implanted in the quadriceps muscle of guinea pigs and assessed his‐tologically at 2 days, 1, 2, 3, 12 and 26 weeks after implantation. All materials were characterized by peri‐implant fibrous connective tissue capsule formation. Von Kossa‐positive calcific material was observed at the implant‐tissue interface of Hydron implants. The amount of apparently calcified material increased with time. Inflammation was not a prominent tissue response for any of the test materials, nor was a foreign body giant cell response.
A Five‐year study of Hudron root canal fillings
Authors: REID R. J. , ABBOTT P.V. , MCNAMARA J. R. , HEITHERSHAY G. S.
Published: September 2007

A prospective clinical and radiographic study was conducted in order to compare Hydron and laterally condensed gutta‐percha/AH‐26 root canal fillings. Paralleling technique periapical radiographs were taken pre‐operatively, postoperatively and at recall appointments at post‐treatment intervals of 6 months, 1 year, 2 years, 3 years and 5 years. Clinical examination at the recall appointments revealed no adverse signs or symptoms amongst all the patients who attended (mean attendance 44.5% at each interval). Radiographs were scored according to the periapical status of the treated root, and comparable bone healing rates were observed between the two root‐filling materials. Among the patients attending recall appointments, there were no radio‐graphic signs of failure of any of the 39 gutta‐percha/ AH‐26 root canal fillings. However, three of the 35 canals tilled with Hydron were classified as failures, and four required further assessment after the 5‐year recall appointment. This study indicated that Hydron and gutta‐percha/AH‐26 root canal fillings were well accepted but, on the basis of radiographic assessment, success with gutta‐percha/AH‐26 was more predictable.
Effect of thermal placement techniques on some physical properties of gutta‐percha
Authors: COHEN B. D. , COMBE E. C. , LILLEY J. D.
Published: September 2007

Some clinical techniques for the placement of gutta‐percha root fillings involve the application of heat. This study was undertaken to assess the effects of intracanal heating techniques on the following properties of gutta‐percha: coefficient of thermal expansion, softening temperature, phase transition temperature and organic content. Samples from each of four products were prepared by three different methods. The materials were studied by thermomechanical analysis, simultaneous thermogravmetry and differential thermal analysis, and by measurement of weight loss on ashing. It was shown that the techniques of gutta‐percha placement involving heating in the root canal caused reversible physical changes in the materials without any apparent change in chemical composition. The average coefficient of thermal expansion was 137 × 10−6/°C, the softening temperature was 55.5°C, there were two characteristic phase changes, and the organic content was 25%.
The physical properties of a new sealing cement
Authors: ONO K. , MATSUMOTO K.
Published: September 2007

This study was performed on a newly developed sealing cement, TS60, to evaluate its physical properties, namely sealing, setting time, compressive strength, solubility and ease of removal. It was compared with Temporary Stopping (GC Dental Industrial Corp., Tokyo, Japan), Eugedain (zinc oxide‐eugenol based material, Showa Yakuhin Kako Co. Ltd, Tokyo, Japan) and Cavit‐G (calcium sulphate based material, Espe Gmbh, Seefeld. Germany), which are typical commercially available sealing cements. The results of the study revealed that TS60 had excellent sealing properties, good compressive strength, low solubility, and was readily removable by heating and melting.
Dentine‐removing characteristics of K‐files energized by the Piezon‐Endo
Authors: BRIGGS P. F. A. , GULABIVALA K. , SETCI‐IELL D. J.
Published: September 2007

This in‐vitro study evaluated the pattern of dentine removal when a size 25 K‐file energized by the Piezon‐Endo was applied to flat surfaces of dentine under standardized conditiuons. The effects of power setting, interfacial force between file and dentine, direction of file oscillation and operator‐assisted movement were examined. Vinyl polysiloxane impressions of the instrumented surfaces revealed characteristic patterns consisting of a series of oblique crests, similar to those observed in a previous study using the Cavi‐Endo. Each crest was parallel to the next and separated by a relatively constant distance. These crests were disposed along the line of contact with the file. The Reflex microscope was used to determine the height width and separation of these crests.

There were differences in the amount and pattern of dentine removal comparecd with the study on the Cavi‐Endo. When the file was held against the dentine surface using the minimum power setting and an interfacial force of 30 g, the pattern of dentine removal was very similar to that produced by the Carvi‐Endo. Increasing the power setting to the maximum recommended for endodontics produced a slight but statistically non‐significant increase in dentine removal. Further increase of the power setting to the absolute maximum produced significantly deeper and wider areas of dentine removal by the apical part of the file. In marked contrast to the Cavi‐Endo, increasing the interfacial force from 30 to 60 g resulted in a significantly greater amount of dentine removal by the coronal part of the file, but there was no reduction in the effect of the apical part of the file.

The superimposition of operator‐induced movement of the file greatly increased the amount of dentine removal as demonstrated by the coalescence of crests to form deep grooves. The grooves tapered relatively evenly, except apically, where the taper increased and the grooves terminated in a point. The crestal pattern would be observed to a variable degree on some of the specimens. The total amount of dentine removed in the ‘operator‐assisted’ groups appeared to be much greater than that in the Cavi‐Endo study.
Microbiological evaluation of the efficacy of chlorhexidine in a sustained‐release device for dentine sterilization
Authors: HELING I. , SOMMER M. , STEINBERG D. , FRIEDMAN M. , SELA M. N.
Published: September 2007

The aim of this in‐vitro study was to evaluate the effect of chlorhexidine in solution and in a sustained‐release device as an intracanal medication. Hollow cylindrical dentine specimens prepared from bovine incisors were incubated with Streptococcus faecalis for a period of 3 weeks. The intracanal medicaments tested were 0.2% chlorhexidine gluconate solution (CM), chlorhexidine in a sustained‐release device (1.2 mg) (SRD), camphorated paramonochlorophenol (CMCP), and a control (no medication). Each medicament was introduced into the lumen of one dentine specimen and incubated for 5 min. 24 h,48 h or 7 days at 3 7°C. The bacteriological samples were taken by shaving the dentine inside the lumen with dental burs ranging in size from ISO 023–033. The dentine powder was collected in test‐tubes containing growth medium and incubated for 24 h. The optical density of the medium was recorded by means of a spec‐trophotometer at a wavelength of 540 nm. There was a statistically significant difference between the control group and all the medicaments tested.
Efficacy of a sustained‐release device containing chlorhexidine and Ca(OH)2 in preventing secondary infection of dentinal tubules
Authors: HELING I. , STEINBERG D. , KENIG S. , GAVRILOVICH I. , SELA M. N. , FRIEDMAN M.
Published: September 2007

This study was conducted to evaluate the efficacy of the antibacterial activity of Ca(OH)2 and a sustained‐release device containing chlorhexidine (SRD) in both sterilization and prevention of secondary infection of the root canal system. Bovine root dentine specimens previously incubated with Streptococcus faecalis were used in this experiment. Two different formulations of the SRD (differing in their cross‐linkage), Ca(OH)2 and normal saline (control) were evaluated. The degree of bacterial infection of the root canal was tested after incubation periods of 24 h, 72 h and 7 days with these medicaments. Their efficacy in preventing secondary infection after recontamination was tested after 72 h and 7 days. The results demonstrated that both formulations of the SRD significantly reduced the bacteria] population in the primary infected groups, as well as preventing secondary infection of the dentinal tubules in the recontaminated group. By contrast, Ca(OH)2 did not show any antibacterial activity, and failed to sterilize the dentinal tubules or prevent secondary infection after recontamination at the time periods examined.
Mandibular premolar with three root canals—two case reports
Authors: CHAN KAM , YEW SIU‐CHUN , CHAO SHOU‐YEE
Published: September 2007

The presence of three root canals in the mandibuiar premolar may sometimes be recognized when there is persistent postoperative discomfort following root canal therapy. This paper presents two cases of root canal treatment of mandibuiar premolars with three root canals including one mandibuiar first premolar and one mandibuiar second premolar. The possibility that there is more than one root canal in lower premolar teeth must be considered in the radiographic and clinical examination during root canal treatment.
Characterization of inflammatory cell infiltrate in dental periapical lesions
Authors: MARTON I. J. , KISS C.
Published: September 2007

Sixty‐three dental periapical lesions were investigated in order to study the involvement of inflammatory and immunologic reactions in the pathogenesis and maintenance of chronic apical periodontitis. Of 61 wellpreserved specimens, 38 were classified as granulomatous, 3 as exudative periapical granulomas and 20 as periapical scars. The quantitative composition of T‐lymphocyte subpopulation and macrophages, the proportion of lgE‐producing cells compared with other immunoglobulin producing plasma cells, and the tissue distribution of IgE‐producing plasma cells compared with that of mast cells were determined in the granulomatous types of granulomas using immunofluorescent, immunohistochemical and enzymehistochemical methods. The results indicated a decreased ratio of helper/inducer versus cytotoxic/suppressor T‐lymphocytes, a remarkably high proportion of macrophages, a low frequency of IgE‐ producing plasma cells with different localization when compared with that of mast cells. These observations suggest that T‐lymphocytes and macrophages may play an important role in the complex events of tissue destruction and repair taking place in the periapical region.
Calcium hydroxide paste in the maxillary sinus: a case report
Authors: G.FAVA LUIZ ROBERTO
Published: September 2007

A case is reported in which a perforation of the sinus floor of the maxillary sinus occurred with extrusion of a calcium hydroxide paste during routine root canal treatment of a maxillary premolar. All clinical manifestations are described as well as the results of a follow‐up evaluation.
Variations in the power output of the Piezon‐Master 400 ultrasonic endodontic unit
Authors: AHMAD M. , ROY R. A. , KAMARUDIN A. G.
Published: September 2007

The present study was undertaken to see if there was any variability in the power output of Piezon‐Master 400 ultrasonic files when driven using different generators, tranducers and file holders. The displacement amplitude of the oscillating tip of the file in air was used as a measure of the power output. The results showed that there was considerable variability in the power output of Piezon‐Master 400 ultrasonic files of similar size and length when driven using different generators, transducers and file holders. In consideration of this, it is recommended that a calibration device be incorporated in the ultrasonic unit so that the operator will have some knowledge of when the unit is working at its maximum efficiency.
A clinical evaluation of one and two‐appointment root canal therapy using calcium hydroxide
Authors: FAVA L. R. G.
Published: September 2007

A clinical study using vital maxillary central incisors was performed to evaluate the incidence of postoperative pain after root canal treatment in one‐ or two‐appointments using a calcium hydroxide‐containing root canal sealer. No differences were observed between the two groups.
Evaluation of the antimicrobial effectiveness of citric acid and sodium hypochlorite on the anaerobic flora of the infected root canal
Authors: GEORGOPOULOU M. , KONTAKIOTIS E. , NAKOU M.
Published: September 2007

This study was designed to evaluate the antimicrobial effectiveness of 25% citric acid, compared with 2.5% sodium hypochlorite, after time intervals of 5, 15, 30 and 60 min. Anaerobic bacterial species were isolated from infected root canals and categorized according to Gram stain as Gram‐positive cocci, Gram‐negative cocci, Gram‐positive rods and Gram‐negative rods. The experimental method used was similar to that proposed by the German society for Hygiene and Microbiology (DGHM) with slight modifications. Testing revealed that citric acid does demonstrate anti microbial properties against anaerobic bacteria, especially against cocci, but it is less effective than 2.5% sodium hypochlorite.
Assessment of coronal leakage in teeth root filled with gutta‐percha and a glass ionomer root canal sealer
Authors: TIDSWELL H. E. , SAUNDERS E. M. , SAUNDERS W. P.
Published: September 2007

The effect on coronal leakage of the use of either a single gutta‐percha cone or cold lateral condensation of gutta‐ percha, with a glass ionomer sealer cement was studied. In addition, the effect of the removal of the smear layer was also determined. Eighty‐eight single‐rooted teeth were prepared chemomechanically using hand files, with the balanced force technique. Lubrication was provided by either Hibiscrub (maintaining the smear layer) or an EDTA ‐containing paste (to remove the smear layer). Copious irrigation was carried out with 2.2% sodium hypochlorite.

The teeth were allocated randomly to four groups of 20 teeth each, the remaining eight teeth served as controls. Two groups of teeth, one with and one without smear layer, were obturated with either a single gutta‐ percha cone or cold laterally condensed gutta‐percha, with Ketac Endo as the sealer. The teeth were stored for 6 weeks, thermocycled, and the extent of coronal leakage determined for each group after immersion in India ink for 90 h. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent. Linear measurement of maximum dye penetration was recorded. The mean depth (+ SD) of leakage for the groups in which the smear layer was left intact was 1.68mm (+0.38) for the single cone (Al) and 2.29 mm (+ 1.58) for lateral condensation (Bl). When the smear layer was removed the mean depth of leakage For the single cone group (A2) was 2.04 mm (+ 0.73) and 2.37 mm (+ 1.70) for the laterally condensed group (B2).

There was no significant difference in coronal leakage between the groups (P>0.05).
Effect of addition of hyroxyapatite on the physical properties of IRM
Authors: OWADALLY I. D. , FORD T. R. PITT
Published: September 2007

The aim of this study was to evaluate the effect of adding 10% and 20% hydroxyapatite (HAP) to Intermediate Restorative Material (IRM) on physical properties such as working time, setting time, compressive strength and disintegration rate. The working and setting times were determined by an indentation method. The ISO recommended method was used to determine compressive strength. The rate of disintegration in vitro was evaluated in buffered sodium citrate at pH 4.5, 5.8, buffered phosphate at pH 7.0 and in bovine serum (pH 6.8), and examined using a replica method and scanning electron microscopy. Kalzinol and EBA were used as control materials for the disintegration experiment. IRM had longer mean working (4 min 43.5 s) and mean setting (6 min 28.5 s) times than IRM + 10 or 20% HAP (P<0.001), the mean reductions being 16% and 9% for IRM + 10% HAP, and 29% and 19% for IRM + 20% HAP, respectively. IRM had a greater compressive strength (68.5 MPa, P<0.01) than IRM + 10% HAP (65.0 MPa) or IRM + 20% HAP (60.0 MPa, P<0.001). Kalzinol, IRM + 10% HAP and IRM + 20% HAP were found to disintegrate after 8 weeks in buffered phosphate and in bovine serum. In contrast, IRM and EBA showed no noticeable signs of disintegration after 6 months in the same media. The physical properties of IRM + 10% HAP and IRM + 20% HAP were reduced compared with IRM but the reductions were not considered to be of clinical significance.