bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemotactic effect of enamel matrix
Authors: LINDSKOG SVEN
Published: September 2007

Summary. Enamel matrix was isolated from forming canine teeth in monkeys and applied to experimental cavities in incisor teeth. In another experiment, enamel matrix from rat incisors was injected intraperitoneally; the peritoneal exudate was collected and grown in vitro. The dentine surface was covered by mast cells while a significant number of mast cells were present in the peritoneal exudate. Enamel matrix appears to be chemotactic for mast cells which may be involved in the initiation of cementogenesis
Bone resorption in periodontal diseases: role of bacterial factors
Authors: JOHNSON N. W. , IINO Y. , HOPPS R. M.
Published: September 2007

Summary. The bone resorbing activity of lipopolysaccharides from oral bacteria has been investigated in vitro. Further, the resorbing activity appeared to be reduced by serum, except in the case of lipopolysaccharide from Bacteroides gingivalis. This micro‐organism is commonly associated with periodontal disease in adults. The significance of lipopolysaccharides stimulating bone resorption in vivo has not yet been resolved.
An assessment in vitro of the sealing properties of Calciobiotic Root Canal Sealer
Authors: COHEN TEOFILO , GUTMANN JAMES L. , WAGNER MARTIN
Published: September 2007

Summary. An assessment in vitro of the sealing properties of a calcium hydroxide based root canal sealer was compared with that of a zinc oxide‐eugenol based sealer. Electrochemical analysis of the leakage patterns revealed that both sealers exhibited leakage, with the calcium hydroxide sealer showing a stabilized or decreased pattern of leakage over time.
Biological evaluation of absorbent paper points
Authors: MÖLLER BENGT , HENSTEN‐PETTERSEN ARNE
Published: September 2007

Summary. The biocompatibility of absorbent paper points was evaluated by a haemolysis test and a tissue culture agarose overlay test. One type of paper points produced marked haemolytic activity and a cytotoxic response in the overlay test. The other types tested showed minimal haemolytic activity and no cytotoxicity. Chemical analysis of the cytotoxic paper points revealed that they contained formaldehyde.
A clinical study using automated instrumentation in root canal therapy
Authors: WEISZ GEORGES
Published: September 2007

Summary. A clinical study of 700 root‐filled teeth with periapical involvement is reported. The canal preparation on all teeth was performed exclusively with girofiles in the Giromatic handpiece. The teeth were followed up 6 months–2 years later, when radiographic evidence showed an absence of periapical lesions in 40 per cent and a reduction in the size of the lesion in a further 56 per cent. The results demonstrate that the Giromatic handpiece is effective in preparing root canals.
The effect of root canal preparation on the shape of the curved root canal
Authors: LIM K. C. , WEBBER J.
Published: September 2007

Summary. This study reports the effect of the step‐bad enlargement technique of root canal preparation on the shape of the curved root canal of extracted human teeth. This was achieved by superimposing tracings made from photographic prints obtained by radiographs of teeth before canal preparation, after apical preparation and after coronal flaring. After apical preparation, the root canal sometimes demonstrated an hour‐glass shape. Flaring the coronal portion of the canal was often successful in opening out the narrowest portion, the elbow, of this hour‐glass shape.
The validity of simulated root canals for the investigation of the prepared root canal shape
Authors: LIM K. C. , WEBBER J.
Published: September 2007

Summary. Curved root canals from extracted human teeth were prepared using K‐type files. The resultant shapes were compared both quantitatively and qualitatively with canals that were formed in polyester clear casting resin and similarly prepared. Moderately curved canals generally demonstrated a funnel‐shaped canal preparation. Severely curved canals showed a high incidence of hour‐glass shaped preparations. When the proportions of the hour‐glass shaped canals from extracted teeth and simulated root canals were compared, there were no significant differences.
Prevalence and distribution of root‐filled teeth in former dental school patients: follow‐up after 10–17 years
Authors: MOLVEN OLAV , HALSE AGNAR , RIORDAN PAUL J.
Published: September 2007

Summary. Out of 431 adults who had teeth root‐filled in the dental school during the period 1963–1969, 238 (55 per cent) attended for re‐examination in 1980. The patients who attended had a mean age of 53 years in 1980, and had 2.8 root‐filled teeth before treatment and 3.9 after treatment in the 1960s. In 1980, they had on average 3.7 root‐filled teeth. The percentage of root‐filled teeth increased from 12 per cent in the youngest age group (26–35 years) to 27 per cent in the oldest age group (66–75 years). Approximately 20 per cent of patients had more root‐filled teeth in 1980 than after treatment in the teaching clinic, while 7 per cent had lost all their endodontically treated teeth. Of teeth recorded as root‐filled after the last course of treatment in the school, 83 per cent were still present in 1980 (100 per cent in the youngest age group, and 78 per cent in the oldest). This age‐related difference in survival of root‐filled teeth is considered to be caused by non‐endodontic factors.
Radiographic study of the root canal system of mandibular anterior teeth
Authors: KAFFE ISRAEL , KAUFMAN ARIEH , LITTNER MARK M. , LAZARSON ALEXANDER
Published: September 2007

Summary. Two‐hundred full mouth periapical radiographic surveys from the files of the School of Dental Medicine, Tel Aviv University, were evaluated in order to investigate the number of root canals in mandibular incisors and canines. A total of 1200 mandibular anterior teeth (400 canines, 400 lateral incisors and 400 central incisors) were examined in their orthoradial radiograph and in the radiograph of the adjacent anatomical area in which the teeth were observed from an eccentric angulation. No correlation between sex or age of the patient and the number of root canals in the mandibular anterior teeth was established. The full mouth periapical radio‐graphic survey provided a diagnostic method for determining the number of root canals of the teeth examined when both the orthoradial and eccentric radiographs of the same tooth were evaluated. The results of the present study in vivo are in agreement with previous studies in vitro.
Histological evaluation of microfilled and conventional composite resins on monkey dental pulps
Authors: HEYS RONALD J. , HEYS DONALD R. , FITZGERALD MARK
Published: September 2007

Summary. The pulpal responses to two micro‐filled composite resins and a conventional composite resin were investigated in adult rhesus monkey teeth. All materials were randomly placed in unetched and unlined class V buccal cavity preparations. A total of 90 teeth were used in the study. Each material was evaluated at 3 days, 5 weeks and 8 weeks. Following perfusion, the teeth were prepared using routine histological procedures. The results indicated that the pulpal response to the microfilled and conventional composite resins were similar for all time periods, characterized by an initial slight to moderate response at 3 days, followed at 5 and 8 weeks by a zero to slight response with evidence of reparative dentine formation. Brown and Brenn staining for bacteria indicated positive staining reactions along the cavity wails of all teeth for all materials at each time period.
Response of rat and guinea‐pig subcutaneous tissue to implanted human roots containing collagen/hydroxyapatite preparations
Authors: CALLIS P. D. , SANTINI A.
Published: September 2007

Summary. The root canals of extracted human roots were cleaned and enlarged. The roots were sterilized before insertion of test materials of collagen, hydroxyapatite or a mixture; saline was used as a control. The roots were implanted subcutaneously in rats or guinea‐pigs. After 30 and 180 days, the embedded roots were prepared for histological examination. In the rat, the tissue reaction was similar whether the roots were filled with collagen, collagen/hydroxyapatite or saline; there was ingrowth of granulation tissue. The canals of teeth filled with hydroxyapadte showed mature fibrous tissue around islands of the material. The response in guinea‐pigs was similar, except that the roots stimulated some bone formation.
Evaluation of a tactile hardness test in indirect pulp capping
Authors: ALAÇAM TAYFUN
Published: September 2007

Summary. The value of a tactile hardness test in indirect pulp capping was investigated by comparing hardness values with the biochemical analysis for phosphorus. Statistically significant differences were found between the 6‐month evaluation groups recorded as soft or medium and those recorded as hard. However, there were no differences between groups evaluated as soft or medium before or after treatment.
Thermomechanical compaction of gutta‐percha. I. A comparison of several compaction procedures
Authors: KERSTEN H. W. , FRANSMAN R. , VAN VELZEN S. K. THODEN
Published: September 2007

Summary. The root canals of 97 extracted, single‐rooted teeth were prepared and filled by thermomechanical compaction of gutta‐percha and an additional 17 teeth were used unfilled as controls to observe dye penetration. By varying the size of the master gutta‐percha cone, the size of the compacting instrument and the amount of gutta‐percha inserted into the root canal before compaction, seven experimental groups were formed. The criteria used for judging the quality of root canal fillings were radiographic examination, dye penetration and adaptation in transverse sections. One method of using the technique proved to be superior to the other six. A significant difference from other experimental methods, however, was only found with radiographic examination and dye penetration, respectively. No significant differences were obtained when the adaptation of gutta‐percha was compared; this was also the case with the combined results of the three criteria.
A laboratory study of four electric pulp testers
Authors: DUMMER P.M.H. , TANNER M. , McCARTHY J.P.
Published: September 2007

Summary. Four commercially available, battery operated, unipolar electric pulp testers were tested and compared under identical laboratory conditions. The form and duration of the electrical impulses varied considerably between the instruments as did the maximum output voltage. None of the models tested passed constant current values when connected to a range of resistances.
The nature of curvature of palatal canals in maxillary molar teeth
Authors: BONE J. , MOULE A.J.
Published: September 2007

Summary. The palatal roots of 100 maxillary first permanent molar teeth and 100 maxillary second molar teeth were examined for degree and nature of curvature in a bucco‐palatal direction.

Eighty‐five per cent of palatal canals of maxillary permanent first and second molar teeth were curved more than 10.

Attention is drawn to the need to use instrumentation techniques which are directed to the maintenance of this curvature, and care should also be taken during preparation of post holes so that the curvature of these root canals is not ignored.
A method of measuring the volume of human dental pulp cavities
Authors: FANIBUNDA K. B.
Published: September 2007

Summary. A method of measuring the volume of the human dental pulp cavity is described.

The crown of an extracted tooth is divided from its root. After cleaning the pulp cavity, it is filled with an elastomer, and the fractured tooth surfaces repositioned before the elastomer sets.

The tooth is corroded in acid to release the elastomer which is then weighed, and its volume calculated.

The method has been applied to representatives of each human tooth type, and mean values are given.
The efficacy of transillumination in vitality tests
Authors: HILL C. M.
Published: September 2007

Summary. Two small studies designed to assess the usefulness of transillumination for testing tooth vitality are described. The results suggest that transillumination is a useful adjuvant to conventional methods of pulp vitality testing, particularly in assessing anterior teeth, or posterior teeth with minimal restorations. The value of combining the results of thermal tests with ethyl chloride and transillumination tests was also investigated, and found to be useful.
Paraesthesia—a consequence of a controversial root‐filling material? A case report
Authors: ALLARD K. U. B.
Published: September 2007

Summary. This is a report of a case where a patient suffered paraesthesia following root filling of her lower left second molar. The Swedish health authorities considered that as a formaldehyde containing root filling cement had been used, the dentist had not worked in accordance with science and proven experience.
Penetration in vitro of human and ferret dentine by three bacterial species in relation to their potential role in pulpal inflammation
Authors: MERYON SYLVIA D. , JAKEMAN K. J. , BROWNE R. M.
Published: September 2007

Summary. Streptococcus faecalis was able to penetrate 5 μm millipore filters and actively grew in the underlying media resulting in death of fibroblast monolayers. It was unable to penetrate 0.45 μm filters and any metabolites which it produced were non‐toxic to these cells. In spite of the reported diameter of human dentinal tubules being 1–5 μm, two bacterial species were unable to penetrate slices of human dentine. From studies using dentine powder this was shown not to be the result of binding to the dentine but from SEM studies it appeared to be due to the presence of the smear layer which occluded the openings of tubules. Removal of the smear layer allowed the rapid penetration of two motile organisms while the penetration of a non‐motile organism was accelerated when a nutrient source was present beneath the slice. Removal of the smear layer in vivo must therefore provide access for bacteria, which enter the microspace beneath restorative materials, to the dentinal tubules. Pseudomonas aeruginosa was able to digest dentine and therefore to penetrate unetched dentine slices. The presence of this organism in vivo may therefore result in severe pulpal damage. In spite of differences in the surface area of dentinal tubules between man and ferret, the pattern of penetration was similar indicating that the smear layer and its removal are much more important than the animal species used in assessing bacterially induced pulpal inflammation.
The incidence of preoperative and postoperative pain in endodontic therapy
Authors: GENET J.M. , WESSELINK P.R. , VAN VELZEN S.K. THODEN
Published: September 2007

Summary. In this study the incidence of preoperative and postoperative pain of endodontic origin of 1204 teeth, treated by 10 dentists, was recorded. All endodontic treatments were completed in one visit except those where lack of time, continuing exudation or treatment to induce apexification did not permit it. The results show that postoperative pain occurred in approximately 29 per cent (7 per cent severe, 22 per cent moderate) of all visits and that there existed a strong positive correlation between the presence of preoperative pain and the incidence of postoperative pain. Based on this observation it is concluded that in studying postoperative pain after endodontic treatment knowledge of the preoperative status is a prerequisite. The results also showed that severe postoperative pain was usually reduced to a tolerable level within 3 days. Out of all treatments that were classified as emergency treatment the therapy chosen relieved the patient's pain in 35 per cent, while in 39 per cent it was reduced to moderate pain and in 14 per cent severe pain persisted. However, only 12 per cent of all these emergency treatments required further treatment.
Periodontal ligament injection: clinical effects on tooth and periodontium of young adults
Authors: RAKUSIN H. , LEMMER J. , GUTMANN J. L.
Published: September 2007

Summary. Periodontal ligament anaesthesia is in wide clinical use in dentistry today. A variety of specialized high pressure syringes have been developed to administer periodontal ligament anaesthesia more efficiently. A clinical study was carried out using the lower first molar teeth on both sides of the mouth of the same patient, providing a test and control tooth, for administration of periodontal ligament anaesthesia. Periodontal ligament injection (PDL‐I) was administered to the test tooth, and conventional inferior alveolar block anaesthesia to the control tooth. The oral hygiene index, gingival index, tooth mobility, tooth vitality and probing depths were measured prior to injection 48 hours postoperatively, and 4 weeks postoperatively. Subjective and objective clinical impressions of depth of anaesthesia, postoperative pain and nature of any postoperative pain were noted at the same time intervals. Observation and measurements were subjected to statistical analysis. The PDL‐I produced no observed or measured changes in either the tooth or the periodontium within the scale of time which was chosen. Acceptance of the technique by patients was mainly favourable, although a few subjects experienced severe postoperative pain.
Apical sealing efficacy of endodontic obturation techniques
Authors: BEATTY R.G. , VERTUCCI F.J. , ZAKARIASEN K.L.
Published: September 2007

Summary. This study in vitro utilized methylene blue dye to evaluate root canal apical leakage after maxillary central incisors were serially instrumented and obturated with laterally condensed guta‐percha and sealer, a single fitted gutta‐percha master cone and sealer, sealer alone or paste alone. The linear extent of dye penetration was measured, and the volume of dye leakage was evaluated using a dye‐recovery spectrophotometric technique. Under the conditions of this study, the teeth obturated with laterally condensed gutta‐percha and sealer exhibited the least leakage. The single gutta‐percha cone and sealer technique had no advantage over use of sealer or paste when used alone.
Postoperative pain after apicectomy. A clinical investigation
Authors: SEYMOUR R.A. , MEECHAN J.G. , BLAIR G.S.
Published: September 2007

Summary. The present study investigated the magnitude and duration of postoperative pain after apicectomy under local anaesthesia in 80 patients. Multiple regression analysis was used to determine the relationship between certain preoperative and operative variables with both the pain experience on the day of surgery and the overall pain experience throughout the 7‐day investigation period. The results showed that postoperative pain after apicectomy is of short duration and reaches its maximum intensity in the early postoperative period. The magnitude of pain does not appear to be dependent upon the operator, sex of the patient or surgical trauma. However, a previous history of acute periapical infection is an important determinant of the postoperative pain experience.
Ultrasonic removal of broken instruments in root canals
Authors: NAGAI O. , TANI N. , KAYABA Y. , KODAMA S. , OSADA T.
Published: September 2007

Summary. A method to remove broken instruments in root canals was developed employing a new ultrasonic device for root canal treatment. The results, using extracted teeth, showed that broken instruments locked tightly in round root canals were more difficult to remove compared with those in irregularly shaped root canals. This method was applied in 39 clinical cases, and in 26 of these the fragment was removed successfully while in six cases it was possible to bypass a file alongside the fragment. Therefore, in 32 out of the 39 clinical cases with broken instruments, it was possible to instrument to the apex.
Determination of formaldehyde in endodontic paper points
Authors: Möller B. , RUYTER I. EYSTEIN , ODDEN E.
Published: September 2007

Summary. The formaldehyde content in four brands of endodontic paper points was determined with an improved 2,4‐dinitrophenylhydrazine (DNPH) method. One brand, earlier shown to exhibit cytotoxic as well as haemolytic activity, contained significantly more formaldehyde than the others.
Pain after chemomechanical preparation
Authors: GEORGOPOULOU M. , ANASTASSIADIS P. , SYKARAS S.
Published: September 2007

Summary. A clinical study was conducted to determine, first the incidence of pain after chemo‐mechanical preparation of root canals, and second what clinical factors were associated with the incidence and degree of pain. Out of the 245 patients in the study 140 (57 per cent) had no pain, 52 (21 per cent) had slight pain, 30 (15 per cent) had moderate pain and 17 (7 per cent) had severe pain. Statistical analysis showed a significantly higher incidence of pain after over‐instrumentation of canals during preparation.
Device for the radiographic examination of teeth in vitro
Authors: WALKER R. T.
Published: September 2007

Summary. A device has been constructed for mounting extracted teeth for radiography in vitro. It allows radiographs to be taken from various angles, and it has been applied to both research and teaching.
Endodontic treatment of root canals obstructed by foreign objects
Authors: FORS U. G. H. , BERG J.‐O.
Published: September 2007

Summary. The causes of iatrogenic root canal obstructions are discussed in this paper. A classifications of the different obstructions is proposed, for which treatment plants with suitable armamentaria are suggested.
An investigation into the movement of sealer during placement of gutta‐percha points
Authors: JEFFREY I. W. M. , SAUNDERS W. P. , THOMAS G. E.
Published: September 2007

Summary. This study investigated the movement of root canal sealer during the placing of a gutta‐percha root filling. Using transparent simulated tooth models, three techniques of introuducing sealer were examined; these were with the gutta‐percha point, with a reamer, or with a Lentulo spiral filler. The use of a Lentulo spiral filler showed consistently more apical extrusion of sealer than with the other techniques. The results demonstrated that the overall coating of sealer was not affected by whatever technique was employed.
Method for inducing reproducible intrinsic discoloration in extracted human teeth
Authors: VAN DER BURGT TINA P. , MULLANEY T. P. , PLASSCHAERT A. J. M.
Published: September 2007

Summary. A method has been developed for producing measurable and reproducible coronal colour changes in teeth in vitro. Two tecfhniques with different access preparations were assessed for the prevention of dehydration of enamel. Rclative discoloration was also compared in freshly extracted teeth and teeth which had been stored in ethanol. The most reproducible results were obtained with an immersion technique of humidity control and with apical access to the pulp chamber. Freshly extracted teeth or teeth stred in ethanol appeared to be equally suitable for determining the relative staining of the crown compared with the original tooth colour. It is considered that the method could be applied to studies for investigating the discolouring properties of endodontic materials.
Periodontal wound healing following intentional root perforations in permaent teeth of Macaca mulatta
Authors: BEAVERS R.A. , BERGENHOLTZ G. , COX C.F.
Published: September 2007

Summary. This study was conducted to: (i) establish a monkey model system for studying the healing of root perforations, (ii) follow and define the normal healing processes of peiodontal tissues after root perforation and attempted repair, and (iii) assess the nature of periodontal tissue responses to a hard‐set calcium hydroxide treatment of experimental root perforations under aseptic conditions. Forty‐eight teeth of two rhesus monkeys were used. Twenty‐four root perforations were treated with a hard‐setting calcium hydroxide compound, while 24, sealed with teflon dises, served as controls. Observation periods were 2, 4, 7, 14, 21 and 42 days; radiographic and histological observations were conducted on each tooth. After the animals were killed, the tissues were demineralized and prepared for histological examination. Radiographs were taken at the time of perforation and again at the time of sacrifice.

Following radiological and histological analysis, a number of observations were made. In both treatment and control groups, the teeth with lateral and furcal perforations presented the same sequence of tissue responses with time. Tissue responses at the wound sites and within the perforation canals were classified into three phases. The initial phase was characterized by blood clot formation, pronounced polymorphonuclear leucocyte infiltration, and incipient necrosis within the periodontal ligament coronal to the lateral lesions. The intermediate phase was characterized by resolution of the blood clot, granulation tissue formation, and resorption of necrotic debris, bone, cementum and dentine fragments. The late phase was characterized by resolution of the inflammation, maturation of the connective tissue, bone tissue healing with proliferation of trabecular bone into the perforation canal, reparative cementum formation along the cut dentinal wall in the perforation canal, and ankylosis in lateral lesions. Only four out of the 48 lesions developed bacterial contamination and abscess formation at the wound sites.
Heat transmission to the outer surface of the tooth during the thermo‐mechanical compaction technique of root canal obturation
Authors: HARDIE ELIZABETH M.
Published: September 2007

Summary. The heat generated at the outer surface of human canine teeth during the technique of obturation of the root canal by thermo‐mechanical compaction of gutta‐percha, both with and without a proprietary root sealer, was measured.

The rise in temperature was recorded at a point on the apical and central thirds of the outer surface of each specimen. The temperature rise was greater at the central area of the root than apically but the use of a sealer gave no statiscally significant difference in temperature. The thickness of dentine did not influence the results. Rises in temperature up to 27°C were recorde.

Three compactors fractured during use. The findings of this investigation would indicate the need for caution and further study before complete acceptance of the technique. The speed and efficacy of the procedure when used in straight canals with closed apices, however, is not in qustion.
Delayed partial pulpotomy in permanent incisors of monkeys
Authors: HEIDE S. , KEREKES K.
Published: September 2007

Summary. Pulpal exposures, approximately 1 mm in size, were created in 35 developing permanent incisors of five monkeys. These were left untreated for one of three time intervals: 4, 48 or 168 hours. After these periods, a standardized partial pulpotomy procedure was performed. When haemostasis had occurred, a layer of Dycal was applied over the pulp stump and the cavity filled with amalgam. Radiographs were taken 1 month and 6 months after treatment. The jaws were removed 6 months after partial pulpotomy and prepared for histological examination.

The clinical examination and 1‐month radiographs revealed no abnormality; on the 6‐month radiographs a periapical radiolucency was observed on one tooth. All teeth showed continued root development over the experimental period. Histologically, 27 pulps had healed, three pulp wounds were incompletely healed, and five, all in one animal, were severely inflamed. Four of these five failures were associated with extensive bacterial contamination. In all teeth, cervical dentine was deposited but the amounts varied considerably.

The success of pulpotomy was not jeopardized by delaying treatment for up to 168 hours after pulpal exposure.
Post crowns: a review
Authors: STOKES A.N.
Published: September 2007

Summary. This review considers the mechanical and biological principles which apply to the design and construction of post crowns. These principles, together with the results of laboratory studies and clinical surveys suggest that post retention should not be gained at the expense of sound root structure, and that while posts in root canals may make teeth more resistant to fracture than their unrestored counterparts, their presence can cause catastrophic root fracture. The cemented, cylindrical post has the highest reported success rate. New designs of threaded cylindrical posts show promise, but do not have the backing of substantial clinical studies.
Aluminium and dental materials—a study in vitro of its potential release and toxicity
Authors: MERYON SYLVIAD. , JAMEMAN K. J.
Published: September 2007

Summary. Aluminium release was investigated from a range of dental materials including several composed of aluminosilicate glass; with the exception of ASPA and Silicap, the release was negligible. The concentrations of aluminium released from these two materials were neither toxic to a fibroblast cell line nor to mouse peritoneal macrophages. Levels in the order of 40ppm were required to exert a toxic effect.
The diagnostic reliability of the buccal radiograph after root canal filling
Authors: KERSTEN H. W. , WESSELINK P. R. , THODEN VAN VELZEN S. K.
Published: September 2007

Summary. The quality of root canal fillings in 172 single‐rooted extracted human teeth as it appeared on the buccal radiograph was assessed and compared with first that on a proximal radiograph, second the amount of linear dye penetration, and third the quality of adaptation and compaction of gutta‐percha observed in transverse root sections. The results justify the conclusion that the clinical radiograph has a limited correlation with first the quality of the root filling ascertained from a proximal radiograph, second dye penetration, and third the stereomicroscopic evaluation of filling adaptation and compaction in transverse root canals that are oval or ribbon‐shaped in transverse section are considered.
The risk of perforation in the curved canal:anticurvature filing compared with the stepback technique
Authors: LIM S. S. , STOCK C. J.R.
Published: September 2007

Summary. Anticurvature filing using the stepback technique was compared with the standard circumferential stepback method, in the mesial roots of 30 extracted human mandibular teeth. Anticurvature filing was shown to reduce the risk of perforation through the furcal surface of the root. A greater risk of perforation into the furcation was found at a level 8 mm from the apex than at 5 mm.
Preoperative and operative factors associated with pain after the first endodontic visit
Authors: GENET J. M. , HART A.A.M. , WESSELINK P. R. , THODEN VAN VELZEN S. K.
Published: September 2007

Summary. Thirteen preoperative and operative factors were investigated regarding their association with the incidence of postoperative pain after the first session of root canal treatment. The final analysis comprised 443 teeth of 443 patients. These were the teeth remaining after the original sample of 1204 teeth was reduced by the exclusion of all teeth associated with irrelevant factors which could possibly affect the analysis. The results showed that postoperative pain after the first visit occurred in 27 per cent of cases (5 per cent severe and 22 per cent moderate pain). Positive correlation occurred between the incidence of postoperative pain and several factors: the presence of preoperative pain in conjunction with a non‐vital pulp; the presence of a radiolucency larger than 5 mm in diameter; the number of root canals of the tooth treated; women reported more postoperative pain than men. Furthermore, the analysis revealed that the effects of these factors were cumulative.
Delayed direct pulp capping in permanent incisors of monkeys
Authors: HEIDE S. , KEREKES K.
Published: September 2007

Summary. The effect of preoperative oral contamination for either 4 or 48 hours on pulpal response to direct pulp capping was studied. Four young monkeys provided a contralateral experimental series of 16 pairs of incompletely developed permaent incisors. Radiographic examination, labelling in vivo, and conventional histological observations at 6 months postoperatively indicated no difference between the two series. All incisors in either series showed continued apical development, and all but one demonstrated increase in cervical dentine. All but two teeth in each series showed apparently fully bridged pulpal wounds. Full bridging generally correlated with normal pulpal conditions; however, in three teeth of the 48‐hour and one of the 4‐hour series, full bridging occurred along with moderate or dense coronal infiltrates of chronic inflammatory cells. All these teeth were mandibular and showed a large denticle formed around dentine chips. Failed bridging seen in two teeth of each series correlated with severe inflammation in the adjacent pulpal tissue. No consistent adverse effect of coronal pulpal inflammation on cervical increase in dentine was recorded.
The influence of observer calibration on radiographic periapical diagnosis
Authors: REIT C.
Published: September 2007

Summary. Radiographic periapical diagnosis is subject to considerable inter‐examiner variation. In the present study the potential of reducing this variation through observer calibration was investigated. Nine well‐experienced examiners were randomly distributed into three groups. Two of the groups were subjected to calibration measures according to different principles. Radiographs of 119 endodontically treated roots were examined at three occasions during a 10‐month period. Both calibration methods used resulted in increased examiner agreement. However, the benefits of the calibration programmes seemed limited. It was argued that this is due to the complex structure of the decision‐making process. A multi‐aspect view of decision‐making is proposed.
Pulpal response to a zinc oxide–eugenol cement
Authors: WATTS A. , PATERSON R. C.
Published: September 2007

Summary. The British Standards Institution have produced a recommended testing procedure for toxicity of dental materials; this advocates the use of a zinc oxide—eugenol cement such as Kalzinol, as a bland control in deep cavities. In this study, Kalzinol was applied directly to the exposed pulps of germ‐free rat molar teeth. This resulted in pulpal inflammation in contact with the material; when dentine particles separated Kalzinol from the pulp, calcific repair tissue was observed without inflammation or necrosis. Further investigation is required into suitable control materials for use in toxicity testing of restorative and lining materials.
Evaluation of the apical seal obtained with two calcium hydroxide based endodontic sealers
Authors: ZMENER O.
Published: September 2007

Summary. In this study, a comparison of the sealing properties of two calcium hydroxide based endodontic sealers, Sealapex and CRCS with those of the root canal cement Tubli‐Seal was performed. The results showed that all materials failed to produce an effective apical seal and that the degree of leakage increased with time. The differences observed among the 1‐, 3‐ and 10‐day observation periods were statistically significant for all materials (P<0.001) whereas no significant differences between materials were observed at each observation period (P<0.05).
Treatment of internal root resorption with thermoplasticized gutta‐percha. A case report
Authors: WILSON P. R. , BARNES I. E.
Published: September 2007

Summary. A case is described in which thermoplasticized gutta‐percha was successfully used to repair a buccal perforation caused by internal root resorption.
Ultrasound and root canal treatment: the need for scientific evaluation
Authors: WALMSLEY A. D.
Published: September 2007

Summary. Ultrasound has recently been introduced into endodontics to aid in the biomechanical preparation of the root canal. Although there are numerous investigations into the clinical efficacy of the endosonic system, there has been a poor understanding of the possible role of the biophysical aspects of ultrasound. Such areas where clarification is required are the possible roles of cavitation and acoustic microstreaming together with the ‘synergistic’ effect of the combined use of ultrasound and irrigant (usually sodium hypochlorite). Furthermore the oscillation of the file within the root canal may be prone to the load applied to it and this will greatly affect its efficiency. The present article aims to clarify these areas and to provide a guide to some of the biophysical terms used within the ultrasound discipline. Further investigations are required however to understand fully the action of the instrument, and it is hoped that this article will provide a basis for a scientific appraisal of endosonics.
Obturation of root canals using the single cone gutta‐percha technique and dentinal bonding agents
Authors: ZIDAN O. , AL‐KHATIB Z. , GOMEZ‐MARIN O.
Published: September 2007

Summary. The quality of the apical seal using the single cone gutta‐percha obturation technique with four different dentinal bonding agents was assessed by measuring the linear penetration of methylene blue dye. No leakage was measurable in 75 per cent of the canals sealed with Scotchbond, 70 per cent of canals sealed with Restodent, 60 per cent of canals sealed with Dentin‐Adhesit, and in 30 per cent of canals sealed with GLUMA. The mean linear dye penetration in canals sealed with these agents was 0.32, 1.95, 0.57 and 2.41mm, respectively. There was no statistically significant difference between the single cone gutta‐percha technique and the laterally condensed gutta‐percha technique when Scotchbond was used as sealer (P > 0.01).
The effect of Giromatic files on the preparation shape of severely curved canals
Authors: SPYROPOULOS S. , ELDEEB M. E. , MESSER H. H.
Published: September 2007

Summary. Two hundred simulated, curved canals with a standardized curvature of 45° were made in clear resin blocks. The blocks were randomly distributed into five groups of 40 each and were prepared using five different instruments, two of which were used in a Giromatic handpiece (Dynatrak and Giro Trio‐Cut) and three were hand‐operated (Unifile, Trio‐Cut and Hedstrom files). All blocks were prepared using the same technique. Evaluation of the prepared canals was done after instrumenting with sizes 25, 30 and 35 to check for procedural errors such as zip, ledge, perforation, hourglass appearance, or broken instrument. Diameters of the prepared canals were also measured after preparation with a size 35 file at four different levels: 1,2,4 and 8mm, from the apex in order to evaluate the taper of the prepared canals. The time needed for each type of instrument to complete the preparation was also recorded. Comparing hand and Giromatic files of the same design showed: (i) no significant difference in number of defects except at size 35 between hand and Giro Trio‐Cut files; (ii) Giromatic files produced wider apical preparations; (iii) hand instrumentation produced a more flared preparation; and (iv) no significant difference in instrumentation time. Hedstrom files showed less defects and more taper, and took less time in preparation of all the instruments evaluated in this study.
Pulp‐capping studies with Analar calcium hydroxide and zinc oxide‐eugenol
Authors: WATTS A. , PATERSON R. C.
Published: September 2007

Summary. Thirteen Sprague‐Dawley rats were deeply anaesthetized and cavities were prepared in the upper first molar teeth. The pulps were exposed and capped with either Analar calcium hydroxide mixed with distilled water, or Analar zinc oxide mixed with eugenol. Serial sections of the teeth were stained with either haematoxylin and eosin or the Gram Weigert stain. Inflammatory infiltrates were observed in the pulps in both groups; dentine bridges were present in a approximately half the teeth in both groups, and bacteria were detected in almost all the teeth. They were confined to the superficial parts of the pulp with little evidence of penetration of vital pulp tissue. Apparently viable micro‐ organisms were observed in direct contact with both materials.
A comparison of the paralleling and bisectin‐angle radiographic techniques in endodontics
Authors: FORSBERG J.
Published: September 2007

Summary. The radiographic reproduction of the apical level of the working length and the root filling during endodontic treatment was examined by paralleling and bisecting‐angle radiographic techniques. The sample consisted of 433 single rooted permanent teeth with complete root formation treated and examined radiographically by a specialist in endodontics. A paralleling technique exposed with a conventional film holder reproduced the distance between the apex and the tip of a root canal instrument or root filling with a very low degree of error. The frequency of deviations was considerably higher when a bisecting‐angle technique was used except at levels flush with the apex, in which case both techniques appeared equal. The deviations most often consisted of the root canal instrument or the root filling being projected shorter, that is, more coronally, on the radiographs exposed with the bisecting‐angle technique than with the paralleling technique.
Vital pulpectomy and root filling with N2 or Endomethasone
Authors: LAMBJERG‐HANSEN H.
Published: September 2007

Summary. Using an aseptic and standardized endodontic technique, vital pulpectomy was performed on 16 pairs of human permanent maxillary front teeth scheduled for extraction in connection with prosthetic treatment. All the teeth had clinically sound pulps before treatment and 16 teeth were root filled with N2 and the other 16 with Endomethasone. In all cases except two, contralateral teeth were used. After 4–8 months the teeth were extracted and processed for histological examination using light microscopy. Histological examination of the residual pulp demonstrated no statistically significant differences between the two root‐filling materials, concerning inflammation and the frequency of necrosis. The healing reactions, occurrence of fibrous tissue in the residual pulp and hard tissue apposition on the root canal wall, were more pronounced after root filling with N2, than after Endomethasone, but the differences were not statistically significant. Comparing the results with those after vital pulpectomy and root filling with zinc oxide‐eugenol cement, total necrosis of the residual pulp was most frequent after root filling with Endomethasone, less so after zinc oxide‐ eugenol cement and least after root filling with N2, but the differences were not statistically significant. When estimated from the local findings, that is the histological reactions in the residual pulp, no advantages could be observed by using N2 or Endomethasone, and owing to the risk of general side effects, because of the formaldehyde content and the complex composition of the two materials routine use of N2 or Endomethasone cannot be recommended in pulpectomy.
Efficiency of different chemical agents in decontamination of gutta‐percha cones
Authors: STABHOLZ A. , STABHOLZ AYALA , FRIEDMAN S. , HELING ILANA , SELA M. N.
Published: September 2007

Summary. Gutta‐percha cones were contaminated with various bacteria, and the efficiency of different chemical agents in their decontamination was studied. Chlorhexidine (2 per cent) and sodium hypochlorite (5.25 per cent) effectively decontaminated the cones within 10 minutes. Ethyl alcohol (70 per cent) and isopropyl alcohol (50 per cent) failed to decontaminate cones infected by bacillus subtilis within 10 minutes, but did so after 60 minutes. Paraformaldehyde tablets required 24 hours to decontaminate the cones of any of the bacterial strains used in this study. These results indicate that chlorhexidine (2 per cent) and sodium hypochlorite (5.25 per cent) may be effectively used as chairside decontaminating agents of gutta‐percha cones in endodontic therapy. They also confirm that paraformaldehyde may be effectively used in the long‐term sterilization of stored gutta‐percha cones.
Investigation of the canal space occupied by gutta‐percha following lateral condensation and thermomechanical condensation
Authors: BEER R. , GÄNGLER P. , RUPPRECHT B.
Published: September 2007

Summary. Since root canal sealers and pastes can cause tissue irritation, the quantity of biologically inert gutta‐percha should constitute more than 90 per cent by volume of the root canal filling. The root canals of 40 extracted incisors with straight root canals were enlarged sequentially to size 50 and the canals were obturated, either by lateral condensation or thermomechanical condensation using standardized gutta‐percha points and Grossman's sealer. After being stored in moistened gauze for 6 hours at 37°C, transverse sections 1 mm from the apex were made, and the area of gutta‐percha in relation to the total cross section of the canal was determined planimetrically using a light microscope. Sections of teeth filled by the lateral condensation method contained 92.7 per cent gutta‐percha, while whose filled by thermomechanical condensation contained 89.1 per cent. As a result lateral condensation continues to be recommended as the filling method of choice for dental practice.
Estimation of the root filling length with the paralleling and bisecting‐angle techniques performed by undergraduate students
Authors: FORSBERG J.
Published: September 2007

Summary. The radiographic reproduction of the root filling length was examined on pairs of radiographs exposed with the paralleling and the bisecting‐angle techniques. The sample consisted of 200 single‐rooted permanent teeth with complete root formation treated and examined radiographically by undergraduate sudents.

A precceding investigation showed that radiographs exposed with film holders for the paralleling technique reproduced the root fillings with a very low degree of deviation from the true length. Therefore in this study the radiographs exposed with the Eggen film holder served as a references for the evaluation of the bisecting‐angle techniqe.

The frequency of deveiations was high when using the bisecting‐angle technique except for roots filled flush with the apex, where both the paralleling and the bisecting‐angle techniques appeared similar. When deviations were recored the root filling was more often projected shorter, i. e. more coronally on the radiographs exposed with the bisecting‐angle technique than with the paralleling technique.

The findings were compared with thsoe of a corresponding study in which the endodontic treatment and radiographic examination were carried out by a specialist. The results in both studies were in broad agreement.
A new instrument for drying root canals
Authors: WAKABAYASHI H. , MASUMOTO K. , TACHIBANA H. , TUZUKI N.
Published: September 2007

Summary. A new method for drying root canals is reported in which an ‘Apical Broach’, which resembles a K‐file without flutes, is used. Absorbent cotton is wound around it to create an instrument suitable for drying root canals. The apical broachcotton instrument can be made at the chairside and is economical.
Treatment of periapical lesions on dog's teeth using periapically extruded Spad
Authors: TZIAFAS D. , PANTELIDOU O.
Published: September 2007

Summary. The method of treating endodontically infected teeth with periapical involvement, by pushing Spad paste beyond the apex, was evaluated both radiographically and histologically 3 months aftr treatment. Sixteen root canals in a dog were used, on which periapical lesions had been experimentally instrumented and filled with Spad paste and gutta‐percha points, after the root canal filling paste had been extruded periapically. The radiographic investigation did not show any evidence of periapical tissur repair or significant absorption of the extruded paste. The most profound histological finding was necrosis of the alvolar bone. Inflammation or extensive necrosos of the apical periodontal ligament, resorption of the teeth and ankylosis were also observed. The rusults of this experiment do not support the use of this method of treatment with Spad.