Showing papers in "International Endodontic Journal in 1993"

Endodontic leakage studies reconsidered. Part I. Methodology, application and relevance.

Abstract: An increasing number of endodontic leakage studies have been published. In the 1990 volumes of Journal of Endodontics and International Endodontic Journal, there was one leakage study to every 4.3 scientific articles. The most popular method was linear measurement of tracer (dye or radioisotope) penetration along a root filling. Comparing some data on linear measurement of dye penetration following the cold lateral condensation of gutta-percha that were published between 1980 and 1990, a high level of variation has been found, although the experimental methods used in these studies were quite similar. In almost all studies evaluating various techniques, the cold lateral condensation technique has been used as a standard control for comparison. The reliability of these results is questionable. The problems with such studies are discussed. It seems that more research should be done on leakage study methodology, instead of continuing to evaluate the sealing ability of different materials and techniques by methods that may give little relevant information.

Factors influencing the success of conventional root canal therapy—a five-year retrospective study

Abstract: This retrospective study on the outcome of conventional root canal therapy was carried out on patients attending the Eastman Dental Hospital between 1970 and 1982. A minimum follow-up period of 5 years was required for patients to be included in the survey. The characteristics of the resulting sample group, the techniques for canal preparation and obturation and the obturating materials used were analysed. The type of obturating material used had no demonstrable effect on success rate but sex, age, preoperative vitality and periapical pathology were associated with significantly differing success rates. Technique also influenced success rate; the method of canal preparation and the position of the apical seal relative to the radiographic apex were both found to be significant. The overall success rate was 84.29%, representing 692 of 821 teeth included in the survey.

Fluid transport and bacterial penetration along root canal fillings

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

Periapical status and prevalence of endodontic treatment in an adult Dutch population

Abstract: This study examined the prevalence of endodontic treatment in a group of 184 Dutch adults, and determined the periapical status of all teeth using panoramic radiographs. The results indicate that in this group, 2.3% of the teeth were root-filled, and that 5.2% of all non-endodontically treated teeth showed signs of periapical pathology. Around the apices of 39.2% of the endodontically treated teeth in this survey, radiographic signs of periapical pathology were observed. Using the level of the root canal filling as a criterion for evaluating the quality of the root canal treatment, 50.6% of the endodontic treatments were qualified as inadequate. There was a significant correlation between the presence of periapical pathology and underfilling of the root canal(s). 44.6% of the patient sample had at least one tooth with radiographic signs of periapical pathology, indicating a substantial future need for endodontic treatment.

The penetration of root canal sealers into dentinal tubules. A scanning electron microscopic study.

Abstract: The purpose of this study was to evaluate the effect of smear layer on penetration of four root sealers into dentinal tubules. Sixty-four, recently extracted, human maxillary and mandibular incisors were used. Following removal of the crowns, the pulps were extirpated and the root canals instrumented. The teeth were then divided into two groups. The teeth in the control group were irrigated with saline solution and the experimental group treated with EDTA and NaOCl. Each main group was then divided into four sub-groups and the root canals filled with Diaket, N2 Universal, SPAD and Forfenan as recommended by the manufacturers. The teeth were split longitudinally and examined using scanning electron microscopy. A quantitative assessment was made of sealer penetration into the dentinal tubules in the coronal, middle and apical parts of each root canal. It was observed that the smear layer obstructed the penetration of the tubules by the sealers. However, in the experimental group, the penetration into dentinal tubules was better with Diaket, N2 and SPAD, than with Forfenan (P < 0.01). It was concluded that this penetration could be affected by physical and chemical properties of root canal filling materials.

Radicular cyst affecting a root-filled human tooth: a long-term post-treatment follow-up

Abstract: Summary Apical periodontitis is caused primarily by microorganisms residing in the root canals of affected teeth. Nevertheless, there is convincing evidence implicating other independent factors that adversely affect the outcome of conventional root canal therapy. In this paper, morphological evidence is presented in support of die potential role of two endogenous factors that may interfere with post-endodontic healing of the periapex. The specimens consisted of a surgical biopsy of an asymptomatic peri-apical lesion which persisted for a follow-up period of 44 months. The biopsy was processed for correlated light and electron microscopy. The lesion was characterized by the presence of a large central lumen lined by a stratified squamous epithelium. The most striking feature of the lesion was the presence of vast numbers of cholesterol crystals which congregated in the connective tissue surrounding the cyst cavity. Extensive light and electron microscopic investigation of the apical part of the root canal and the lesion foiled to reveal the presence of microorganisms. These findings strongly suggest that intrinsic factors like the accumulation of certain tissue break-down products such as cholesterol crystals, and the cystic condition of the lesion itself, can adversely affect the healing process of the periapex following root canal therapy. Consequently, such apical lesions can remain refractory to conventional endodontic therapy for long periods of time.

Root canal morphology of maxillary permanent first molar teeth at various ages

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

In vitro cleaning ability of root canal irrigants with and without endosonics

Abstract: A variety of methods have been used to evaluate the cleanliness of root canals after endodontic preparation and irrigation. Few irrigation agents other than sodium hypochlorite (NaOCl) have been tested in conjunction with endosonics. The purpose of this study was to examine the cleaning ability of water, NaOCl, Hibiscrub and a biological washing liquid when used as intracanal irrigants, with and without endosonics. Two methods of evaluation were employed to assess the root canal cleanliness after endodontic preparation. A total of 56 teeth, divided into eight groups, were prepared manually using the step-down technique. Each irrigating agent was used in two experimental groups, with and without endosonics. Two additional teeth which received neither instrumentation nor irrigation served as the controls. The teeth were split longitudinally and the state of cleanliness of the root canal was assessed by scoring the amount of stained organic debris and smear layer. It was demonstrated that the results of debris and smear layer scoring were significantly influenced by the type of irrigant and whether endosonics had been used. All agents exhibited similar cleaning ability when introduced manually. With endosonics, NaOCl yielded significantly less stainable debris (P < 0.05) than the other groups which showed no significant difference. The ability to remove the smear layer was enhanced, but at some distance short of the working length, by endosonics for all irrigants tested. None of the solutions tested was able to produce a canal wall that was free of smear layer.

Adaptation of injected thermoplasticized gutta-percha in the absence of the dentinal smear layer

Abstract: The adaptation of thermoplasticized, injected gutta-percha to prepared dentine devoid of smear layer was examined with SEM. Findings indicate a penetration of gutta-percha into the patient dentinal tubules with or without root canal sealer. The clinical implications of these findings are discussed.

Characterization of inflammatory cell infiltrate in dental periapical lesions.

Abstract: Summary 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.

Endodontic leakage studies reconsidered. Part II. Statistical aspects.

Abstract: The aim of many endodontic studies is to compare two or more treatment methods, techniques or materials, for example, to detect differences in mean leakage scores. As it is not feasible to study large populations, samples are taken. The important question then arises as to how large the sample sizes have to be in order to establish the 'true' (= populations') mean scores. First, it must be determined which magnitude of the difference (= v) between the mean scores is of endodontic interest. Based upon v and a few related statistical parameters, one may calculate how large the samples must be in order that a statistical test yields a significant result for a difference that is of endodontic importance. In other words, the 'power' of a test, depending on the sample size among other factors, must be large enough to detect the 'true' a priori determined difference between the populations. The use of small sample sizes may imply that a rather large difference between two mean leakage scores is not found to be significant, thereby leading to incorrect conclusions. This article describes the power and the statistical related factors that determine the adequate size of samples. Examples of power calculation are presented. Next, the power of publicized endodontic leakage studies was evaluated. Almost two-thirds of the sample sizes were 10 or less, and about 90% were 20 or less. Less than one-half of the tests had an adequate power (conventionally > or = 0.80). It is necessary to be cautious when extrapolating the results of such studies, because of the limited power of the statistical tests. The power may be increased by using larger sample sizes or, alternatively, by enlarging the 'effect size', by either taking an interest in a larger difference between the mean scores, or by minimizing the variability of the data.

Management of the resected root end: a clinical review.

Abstract: Summary Careful management of the resected root end during endodontic surgery is critical to the overall success of the case. After resection, the root structure presents with multiple anatomical variations and considerations at both a macroscopic and microscopic level. These include root outline, canal anatomy, dentinal tubule configuration, presence of a smear layer and root canal filling material. Proper assessment of these variables will dictate the best methods for root-end management, along with the attainment of an anatomically compatible root face for optimal healing of the periradicular tissues.

A comparison of endodontic treatment results at two dental schools.

Abstract: Summary Endodontic treatment results were assessed in a controlled clinical study in Arhus. Undergraduate students used either Kloroperka or AH26 as sealer in a randomized fashion. The findings were compared with the results from a previous study of identical design in Oslo, which involved Kloroperka, AH26 and ProcoSol. While Kloroperka performed slightly, but significantly less well than AH26 or ProcoSol in the Oslo study, no difference was found between Kloroperka and AH26 in the present study. The overall treatment results were poorer in Arhus than in Oslo, but this might be explained by a marked difference in the preoperative diagnoses and in the technical problems associated with the teeth selected for treatment. When results of endodontic treatment carried out at different locations are compared, variations in case selection and preoperative diagnoses must be corrected for in order to obtain an adequate basis for comparison.

Dental anxiety: a cause for possible misdiagnosis of tooth vitality

Abstract: Fear, anxiety and anticipation of pain are prepotent emotional and cognitive mediators of pain behaviour. As pain is often used as a parameter for evaluation of tooth vitality, existing dental anxiety may occasionally lead to possible misdiagnosis. A representative case is presented in which dental anxiety led to an initial misdiagnosis of endodontic pathology.

The relationship between the root canal filling and post space preparation

Abstract: The restoration of root treated teeth often requires the use of posts. Their use may affect the quality of the seal of the root canal filling. The various aspects of the relationship between root canal filling and post space preparation are discussed in this review. It is recommended that the use of posts should be avoided whenever possible. Where the preparation of post space is required, immediate removal of gutta-percha using heated instruments and small Gates Glidden drills is the method of choice.

Antibacterial properties of eight dental cements

Abstract: Summary The antibacterial action of a light-cured glass poly-alkenoate Vitrebond and an adhesive resin luting agent Panavia Ex was investigated and compared with six previously tested dental cements. The bacterial cultures used were six strains of Streptococcus mutans, six of Streptococcus sanguis and six cultures of carious debris from carious lesions. A modification of the agar diffusion method was used to test the antibacterial action of freshly mixed cements. In addition the cements were allowed to set and their antimicrobial action was tested by incubation for 5 days in sucrose broth inoculated with the test cultures. All the freshly mixed materials had an antibacterial action. A two-way analysis of variance and Tukey–Student range analysis showed that Vitrebond had a significantly greater zone of inhibition than Aquacem, IRM, Dycal. Dycal VLC, Ceramco and GC Elite (P=0.001). Freshly mixed Panavia Ex exhibited minimal antibacterial action. After 5 days the antibacterial properties of alt the cements were reduced.

Success of pulpotomy in the management of hyperplastic pulpitis

Abstract: Hyperplastic pulpitis is a variety of chronic open pulpitis which is regarded as irreversible. This condition is usually treated by root canal treatment, unless coronal damage does not permit restoration, in which case extraction is indicated. In the present study, 24 permanent teeth of individuals, aged 10-22 years and diagnosed as hyperplastic pulpitis were treated by pulpotomy using an atraumatic surgical technique with calcium hydroxide alone. The treatment was successful in 22 teeth, according to the following criteria: absence of clinical symptoms, absence of any intraradicular or periradicular radiographic pathological changes, presence of dentine bridge detected by clinical examination and sometimes observed radiographically, and sensitivity to electrical stimulation. The follow-up examination ranged from 12 to 48 months. The high frequency of clinical healing in this study appears to justify recommending pulpotomy as the treatment regime in selected cases of chronic hyperplastic pulpitis.

An in vitro study of the quality of root fillings in teeth obturated by lateral condensation of gutta‐percha or Thermafil obturators

Abstract: Summary The aim of this in vitro study was to assess the quality of root canal obturation and degree of linear apical dye penetration in teeth root filled with either laterally condensed gutta-percha or Thermafil obturators, A total of 150 teeth with single roots were included in the study. All canals were prepared using a standard step-back technique with anticurvature filing. Radiographs taken of the teeth to show the maximum degree of canal curvature were then exposed and the angle, radius and position of curvature determined. This information about the canals, together with their working length and diameter at end-point, was used to divide the teeth into two experimental and two control groups. A total of eight teeth were excluded because of technical difficulties, 65 were filled with Thermafil obturators, 63 were filled with laterally condensed gutta-percha whilst 14 teeth remained unfilled and acted as controls. Following obturation, the teeth were radiographed in two planes and the technical quality of fill assessed on a four-point scale. All access cavities were then sealed and the teeth immersed in dye for 48 h before being split longitudinally. Linear dye penetration via the apical foramen was then assessed. Canal obturation with Thermafil obturators (0.7 min) was significantly quicker (P > 0.001) than lateral condensation (6.4 min). Apical extrusion of sealer and gutta-percha occurred significantly more often with Thermafil obturators but there was little difference in the technical quality of the fillings and no significant difference in dye penetration. Under the conditions of this study, Thermafil obturators proved a satisfactory alternative to lateral condensation of gutta-percha.

In vitro release of calcium and hydroxyl ions from two types of calcium hydroxide preparation

Abstract: Summary Non-setting and setting pastes are the most common forms of calcium hydroxide, used in endodontics. The aim of this study was to investigate the differences in the availability of calcium and hydroxyl ions from some commercial preparations of both types. In vitro released calcium and hydroxyl ions were determined by a potentiometric method, after diffusion through sintered glass. The non-setting pastes evaluated were Calcipulpe, Calxyl Red, Calxyl Blue and Cinacal; while setting base materials were represented by Dycal, Nu-Cap and Reolit. The data obtained showed significantly higher availability of calcium and hydroxyl ions from non-setting pastes, compared with‘alkaline cements’(P>0.05). Great variations in the amount of released ions were also found among samples of the same material.

The vibratory pattern of ultrasonic files driven piezoelectrically.

Abstract: Summary The pattern of oscillation of a Piezon-Master 400 ultrasonic file driven by a piezoelectric transducer was studied in air and on water. In addition, the displacement amplitudes of the files were measured. The findings were compared with those observed with the Cavi-Endo unit reported in another study (Ahmad 1969). It was observed that the file vibrated such that a standing wave was formed on the file and it exhibited points of maximum deflection (antinode) and points of minimum deflection (node) with the largest deflection occurring at the apical end. This pattern of oscillation was similar to that exhibited by the Cavi-Endo file which employed a magnetostrictive transducer. However, the displacement amplitudes were very much higher than those exhibited by the Cavi-Endo. It is considered that the 120° angle of the file holder inherent in the Piezon- Master 400 unit and the more effective power transmission with the piezoelectric transducer may have contributed to the large amplitudes.

Temperature and surface changes of dentine and cementum induced by CO2 laser exposure

Abstract: The thermal effects of a CO2 laser on the external root surface and inside the root canal were studied in vitro by means of computerized infrared (IR) thermography and a digital thermometer. One-hundred-and-eighty tooth roots with single root canals were irradiated internally and externally with laser power set at 0.5, 1, 1.5, 2, 3 and 4 W. The laser was used in two operating modes: pulsed (pulse 0.5 s) and continuous mode with exposure time of 10 s. Under the conditions of this experiment, temperature rises of between 1.5 and 19.1 degrees C at the external root surface and 1.5 and 12 degrees C inside the root canal and horizontally across the sectioned root surface were recorded. The results obtained with IR camera showed a higher temperature on the external root surface than the digital thermometer during and after lasing the root canal. Scanning electron microscope (SEM) analysis revealed that even low laser energy significantly damaged the external root cementum surfaces.

Failure behaviour of fatigue-tested post and cores.

Abstract: Evaluation of the long-term behaviour of restorations in clinical trials can be time-consuming. A partial alternative to the clinical trial can be found in mechanical fatigue testing. The aim of this study was to evaluate the failure behaviour of post and core restored teeth when subjected to cyclic mechanical loading and to compare it with quasistatic failure. Eighty seven premolar teeth were restored with a titanium alloy post and an amalgam or composite core. Five to 21 days after restoration, the specimens were subjected to cyclic loading (frequency 5 Hz), at an angle of 45 degrees to the long axis of the tooth. The load levels were 50, 60, 65 and 70% of mean quasistatic failure loads. The specimens were divided into three groups according to their survival time: short (S) ( or = 10(5) cycles). For both core materials failure behaviour changed after approximately 10(5) cycles, and the change was most marked for the composite group. Catastrophic fatigue failure consisted of core fracture in the amalgam group (three times) and of post fracture in the composite L group (four times). Three post fractures occurred at a site theoretically predisposed to fatigue failure. It was concluded that fatigue failure characteristics of post and core restorations may be very different from those of quasistatic failure. Therefore, in addition to quasistatic tests, fatigue tests are necessary, covering at least 10(5) load cycles.

Presence of natural killer cells in human chronic periapical lesions

Abstract: Natural killer (NK) cells are lymphoid in nature and appear to kill target cells (neoplastic and virus-infected cells) without apparent prior immunization. Ten human chronic periapical lesions were examined for the presence of these cells. The lesions were collected, frozen in liquid nitrogen, and sectioned. They were then stained with an indirect immunoperoxidase procedure for the presence of human NK cells. Human tonsils and human periapical scar tissue were used as positive and negative controls. The results showed absence of NK cells in scar tissue and the presence of NK cells in tonsils and all samples of human periapical lesions. NK cells may play a defensive role in controlling root canal infections or, possibly, a role in its pathogenesis.

Light‐cured glass ionomer cement as a retrograde root seal

Abstract: A light-cured ionomer cement was investigated as a retrograde root seal, without a retrograde cavity. This was compared with the material used in a retrograde cavity, and with a conventional glass ionomer cement, as a seal. The adaptation and sealing ability of the test materials were assessed using a confocal optical microscope with a fluorescent dye. The root canals of 40 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were subsequently apicected, then divided into four equal groups. In one group, a retrograde cavity was prepared, and the light-cured glass ionomer cement was placed as a retrograde root filling. No retrograde cavities were prepared in the three remaining groups. The light-cured glass ionomer cement was applied directly onto the apicected root face. Two different thicknesses of light-cured glass ionomer cement were tested, a thin layer (approximately 1 mm) in one group, and a thicker layer (> 1 mm) in another group. A conventional glass ionomer cement was used in the last group, and applied directly onto the root face in a single thickness (approximately 1 mm). In the group where the light-cured glass ionomer cement was used in a retrograde cavity, the material was often well adapted to one cavity wall, but gaps were found on the opposite wall. The light-cured and conventional glass ionomer cement retrograde root seals were well adapted to the root face, regardless of the thickness of material used. The thinly applied (approximately 1 mm) light-cured glass ionomer cement retrograde root seals permitted the least leakage.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimentally induced dentoalveolar ankylosis in rats

Abstract: Dentoalveolar ankylosis is a common complication after replantation of teeth with injured periodontal ligaments. This is a serious complication for the tooth since it leads to progressive root resorption. In young individuals it may also cause infra-occlusion and reduced development of the alveolar process. The purpose of this study was to develop a method applicable to rats in order to follow the effect of systemic and local factors on the development of ankylosis and their possible effect on the length of the functional period of the ankylosed tooth before exfoliation. The maxillary first molars in adult rats were extracted. The periodontal ligaments were devitalized or removed before replantation of the teeth. Dentoalveolar ankylosis was clinically established 2 weeks after replantation. Induction was most reproducible after devitalization or removal of the PDL cells with Dakin's solution and after keeping the rats on a liquid diet up to 3 weeks after replantation. Exfoliation of the teeth usually occurred 6 weeks after replantation. Histological examination showed that the PDL was replaced by bone. The ankylosed teeth showed root resorption to a varying degree. The resorption was in some cases occasionally located in the supra-crestal part of the tooth. A bone-like tissue in the root canal was a rather common finding. In one of the ankylosed teeth cartilage formation was found adjacent to the cementum.

Root canal treatment on patients with HIV infection

Abstract: Summary Patients attending a dedicated dental clinic during the previous 24 months were assessed for the success of root canal treatment. Two groups, totalling 48 patients, had root canal treatment to 57 teeth performed by one operator. All treatment was carried out without antibiotic prophylaxis over two or more appointments. Patients with HIV infection had root canal treatment to 40 teeth. Sixteen patients in the control group had root canal treatment to 17 teeth. Short-term success was determined by follow-up appointments 1–3 months following obturation. No complications were experienced in either group, except with one HIV infected patient. The results of this clinical study indicate that root canal treatment can be carried out following standard procedures and without antibiotic prophylaxis.

The use of E‐speed film for root canal length determination

Abstract: This study compared the use of D-speed and E-speed dental X-ray film for assessing the working length of root canals. Root canal files of varying size (ISO 06, 08, 10 and 15) were placed in the root canals of a maxillary molar and a mandibular molar in a dried skull and mandible. Files were set at various lengths relative to the radiographic apex. The X-ray projections were kept constant. Exposure settings for the two film types that gave comparable radiographic density were selected. Films were developed manually under standardized conditions. A total of 48 films of each type were examined at various magnifications by four trained examiners for the estimation of distance between the file tip and radiographic apex. There were no differences between examiners in estimating working length. The effect of file size, root and magnification were also not significant. The differences between the film types were not significant (P > 0.05). It is concluded that clinicians should use E-speed film instead of D-speed film for root canal length measurement, because the exposure time was reduced by over 40% but the quality of the radiographic image was not significantly different.

Calcium hydroxide paste in the maxillary sinus: a case report.

Abstract: 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.