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PubMed1997

Comparison of two endodontic handpieces during the preparation of simulated root canals.

The objective of this in vitro study was to compare and assess two endodontic handpieces during the preparation of simulated root canals. One hundred and sixty simulated root canals in clear resin blocks, of two angles and positions of curvature, were prepared using either Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besançon, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). Files of 21-mm or 25-mm length were used. When preparing the canals, the files were used either in line with or perpendicular to the canal curvature. Preparation of the canals was carried out using a technique described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including an assessment of the canal preparation time, the deformation or fracture of instruments, loss of canal length, weight loss from the resin blocks and the overall postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic Air handpiece took significantly more time (P < 0.001) to prepare the canals and was associated with both more loss of working length (P < 0.05) and more loss of weight (P < 0.001). Both handpieces created a high percentage of aberrations in the shapes of prepared canals. The MM1500 Sonic Air handpiece created significantly more aberrations than the Excalibur handpiece (P < 0.05 for zip and elbow, P < 0.05 for danger zone and coronal narrow). The effects of the variables, canal curvature, file length and the plane of use of the file, on the performance of the handpieces, were also assessed.

Acrylic Resins↗
PubMed1998

A comparison of digitally scanned radiographs with conventional film for the detection of small endodontic instruments.

The use of computers in dentistry is becoming common as a practice tool for a diverse number of tasks, including the storage and enhancement of intra-oral radiographs. Several systems of digital radiography are available to produce a digital image including irradiation of a charged-couple device and scanning conventional radiographs. This study compared various digital images of scanned periapical radiographs with the original radiographs to determine whether the digitized images offered any advantage when viewing small files at the radiographic apex. Twenty extracted permanent molar teeth were prepared by gaining straight line access to the root canals and a ISO size 06 K-file was introduced into one of the canals until the tip was flush with the apical foramen. Using a standardized technique, radiographs were taken of the teeth using E-speed film. The radiographs were scanned and five digital images: original, enhanced, negative to positive conversion, zoom and zoom of negative to positive were produced. Three evaluators compared each of the images with the radiograph for clarity of the endodontic file in relation to the radiographic apex. Results were analysed using the Wilcoxon signed rank test and the Kappa (kappa) test was used to measure the level of agreement between the three evaluators. The results revealed that all the digital images produced by this scanner were inferior to the radiograph (P < 0.001) and that there was high agreement between evaluators.

Dental Instruments↗
PubMed1999

A comparative study of the removal of smear layer by three endodontic irrigants and two types of laser.

AIM: The effects of three endodontic irrigants and two types of laser on a smear layer created by hand instrumentation were evaluated in vitro in the middle and apical thirds of root canals. METHODOLOGY: Sixty human mature extracted mandibular premolar teeth with a single root canal and a closed apex were distributed randomly into five groups of 12 teeth each. Whilst cleaning and shaping up to a size 60 master apical file with a step-back technique, the root canals were irrigated with 3 mL of 5.25% NaOCL and 3% H2O2, alternately, between each file size. Group 1 (G1) were control specimens that were irrigated with a final flush of 17% EDTA. The teeth in group 2 (G2) were irrigated with a final flush of 6% phosphoric acid, and group 3 (G3) with 6% citric acid. In the specimens of group 4 (G4) the root canals were irradiated with a carbon dioxide (CO2) laser, and specimens of group 5 (G5) were irradiated using an Er:YAG laser. The teeth were split longitudinally and prepared for examination by scanning electron microscopy. RESULTS: Control specimens (G1) showed clean root-canal walls with open dentinal tubules in the middle one-third, but in some specimens thick smear layer was observed in the apical one-third. Specimens irrigated with a final flush of 6% phosphoric acid (G2) or 6% citric acid (G3) were cleaner than with 17% EDTA, showing very clean root canal surfaces in the middle one-third but in the apical one-third the smear layer was not completely removed, especially at the openings of the dentinal tubules. The specimens irradiated with the CO2 laser (G4) showed clean root-canal walls with the smear layer absent, charred, melted, recrystallized and glazed in both middle and apical thirds. The root-canal walls of the specimens irradiated with the Er:YAG laser (G5) revealed an absent smear layer with open dentinal tubules in the middle and apical thirds. Statistical analysis showed no significant difference in the cleanliness of root-canal wall between G1 and G2, and G1 and G3. However, there were statistically significant differences (P < 0.01) between G1 and G4, and G1 and G5 in the cleanliness of the middle and apical one-thirds of the root canals. CONCLUSIONS: Irrigation with 17% EDTA, 6% phosphoric acid and 6% citric acid did not remove all the smear layer from the root-canal system. In addition, these acidic solutions demineralized the interbular dentine around tabular openings, which became enlarged. The CO2 laser was useful in removing and melting the smear layer on the instrumented root-canal walls and the Er:YAG laser was the most effective in removing the smear layer from the root-canal wall.

Carbon Dioxide↗
PubMed1999

Antimicrobial effects of various endodontic irrigants on selected microorganisms.

AIM: This study was undertaken to determine the antimicrobial effect of various endodontic irrigants against six selected microorganisms. METHODOLOGY: Staphylococcus aureus, Enterococcus faecalis, Streptococcus salivarius, Str. pyogenes, Escherichia coli and Candida albicans were included in the study. Pre-sterilized Whatman paper discs, 6 mm in diameter and soaked with the test solution, were prepared and placed onto the previously seeded agar Petri plates. Each plate was incubated aerobically. A zone of inhibition was recorded for each plate and the results were analysed statistically. RESULTS: 5.25% NaOCl was effective against all test microorganisms with a substantial zone of inhibition. Saline was always ineffective. Decreased concentration of NaOCl significantly reduced its antimicrobial effect. Cresophene showed a significantly larger (P < 0.05) average zone of inhibition compared to the other experimental irrigants. Alcohol had smaller but not significantly different zones of inhibition than chlorhexidine. CONCLUSIONS: 5.25% NaOCl was superior in its antimicrobial abilities compared with other irrigants used. A reduced concentration of NaOCl (0.5%) resulted in significantly decreased antimicrobial effects. When compared with 21% alcohol, 0.5% NaOCl and 2% chlorhexidine, paramonochlorophenol (cresophene) showed a greater antimicrobial effect.

Analysis of Variance↗
PubMed1999

Thermal sensitivity of endodontically treated teeth.

CASE REPORTS: The problem of thermal sensitivity following non-surgical root-canal treatment is explored and case reports are presented. Possible causes for post-treatment discomfort from endodontic and restorative aetiologies are discussed, as are the mechanisms to explain the patients' painful experiences. Treatment of this problem may vary from the simple replacement of a defective restoration to a more extensive non-surgical retreatment of the case, despite radiographic evidence of an acceptable root filling and normal periradicular tissues.

Cold Temperature↗
PubMed1999

The shear bond strength of glass ionomer cement sealers to bovine dentine conditioned with common endodontic irrigants.

AIM: The aim of this in vitro study was to evaluate the shear bond strength of commercially available and experimental glass ionomer cement (GIC) sealers to dentine exposed to common endodontic irrigants. METHODOLOGY: The enamel of 90 bovine incisor crowns, randomly divided into nine equal groups, was ground to expose the superficial dentine layer. The exposed surface was conditioned with either: (i) distilled H2O; (ii) 2.6% NaOCl; or (iii) 17% EDTA followed by 2.6% NaOCl. Five cc of each irrigant was applied over a 30-second period. The following GIC sealers were tested: (i) Ketac-Endo; (ii) KT-308, an experimental sealer; and (iii) ZUT, a combination of KT-308 and an antibacterial agent (0.2% by weight). The test sealers were applied to form cylinders with a standardized contact surface area (17.8 mm2) on the conditioned dentine surfaces. Specimens were bench set for 90 min and stored in distilled water at 37 degrees C for 48 h, then tested to failure for shear bond strength (MPa) in an Instron machine. RESULTS: KT-308 and ZUT had significantly higher MPa values than Ketac-Endo (two-factor ANOVA, P < 0.0001), regardless of the dentine conditioning. All specimens conditioned with 17% EDTA and 2.6% NaOCl combined had significantly lower MPa values than those conditioned with water or 2.6% NaOCl alone (P < 0.02). CONCLUSIONS: It was concluded that the experimental sealers KT-308 and ZUT bonded better to bovine dentine than Ketac-Endo, and that the bond of all three GIC sealers was better with the smear layer present.

Adhesiveness↗
PubMed1999

Assessment of apical and coronal root canal seals using contemporary endodontic obturation and restorative materials and techniques.

AIM: The purpose of this study was to evaluate the sealing ability of two contemporary endodontic obturation and restorative techniques and materials. METHODOLOGY: Seventy-nine extracted human single-rooted teeth were distributed randomly in two experimental groups of 36 and 37 specimens (groups 1 and 2, respectively), one group of three positive controls and one of three negative controls. The teeth were radiographed preoperatively, accessed, and instrumented. After smear layer removal, the teeth in group 1 were obturated using the System B and Obtura and were restored coronally with Core Paste using Tenure as a bonding agent. The teeth in group 2 were obturated using the Microseal technique and were restored coronally with amalgam using Panavia 21 as a bonding agent. All teeth in groups 1 and 2 were coated with three layers of nail varnish on all of their surfaces apart from the apical 4.0 mm and the coronal area above the cemento-enamel junction. The positive control teeth were obturated, restored coronally and completely coated with varnish, whereas the negative control teeth were not obturated, restored coronally, nor coated with varnish. The teeth were radiographed postoperatively and retained in saline solution for 10 days. For the next 10 days they were submerged in India ink. Subsequently all teeth were demineralized, dehydrated and rendered transparent. Dye penetration was measured using a stereomicroscope. RESULTS: All materials and techniques provided minimal to zero dye penetration, apart from one specimen in the Core Paste group that showed 4.0 mm of dye penetration. The Wilcoxon rank sum test and t-test showed no statistically significant differences and all materials and techniques tested presented with a high degree of acceptability. CONCLUSIONS: It was concluded that these contemporary techniques and materials provide equally good results, but long-term studies are needed for outright inferences to be drawn relative to their clinical performance.

Coloring Agents↗
PubMed2000

Evaluation of apical sealing of three endodontic sealers.

AIM: The apical sealing ability of three different endodontic sealers was evaluated in extracted teeth using dye penetration. METHODOLOGY: The root canals of 99 extracted human maxillary central incisors were prepared sequentially 2 mm beyond the apical foramen with a size 55 Nitiflex file. The teeth were divided into three experimental groups and obturated by lateral condensation of cold gutta-percha and one of the following sealers: group 1, zinc oxide and eugenol sealer (Fill Canal); group 2, glass ionomer sealer (Ketac-Endo) and group 3, epoxy resin sealer (AH Plus). The teeth were covered with nail varnish to within 1 mm of the apical foramen and immersed in 2% methylene blue in a reduced pressure environment for 24 h. After this period, the teeth were washed and cut longitudinally for apical leakage analysis. The values were obtained from the maximum depth of leakage as well as the average between the maximum and minimum values observed for each group. RESULTS: Statistical evaluation of the results showed no significant difference in the leakage between Fill Canal and Ketac-Endo (P > 0.05). Leakage with AH Plus was significantly less (P < 0.01) than with the other sealers. CONCLUSIONS: All three sealers allowed some leakage to occur. Leakage with AH Plus was significantly different than with Fill Canal or Ketac-Endo.

Barium Sulfate↗
PubMed2001

Antimicrobial effectiveness of electro-chemically activated water as an endodontic irrigation solution.

AIM: The aim of this in vitro study was to evaluate the antimicrobial effectiveness of electro-chemically activated water (ECA) as an endodontic irrigation solution. METHODOLOGY: The root canals of 60 caries-free, single-rooted, adult, maxillary, anterior human teeth were instrumented and irrigated in a similar method to that used for in vivo root canal treatment. The external root surface of each tooth was sealed, maintaining the access cavities patent and the root canals were inoculated with a suspension containing four bacteria. The teeth were randomly divided into four groups (n = 15). Each group was irrigated ultrasonically with one of the following solutions: distilled water (control), NaOCl (3.5%), and ECA, the latter at pHs 7.0 and 9.0. Antimicrobial effectiveness was established directly after irrigation and again 7 days later, by counting colony-forming units on blood agar plates and by spectrophotometric analysis. RESULTS: Large numbers of bacteria were present in the canals of teeth irrigated with distilled water. No bacteria were observed following irrigation with NaOCl. Neither of the ECA solutions were found to be effective against all the bacteria. Although some reduction in the number of bacteria was evident in the ECA groups, this was not statistically significant (P > 0.05) when compared to sodium hypochlorite. CONCLUSION: Within the confines of this study ECA did not demonstrate antimicrobial effectiveness.

Adult↗
PubMed2001

A study of endodontic treatment carried out in dental practice within the UK.

AIM: The purpose of this study was to gather both qualitative and quantitative information on the nature of root canal treatment carried out by a group of dentists working within the United Kingdom. METHODOLOGY: A two-part questionnaire was posted to 720 dentists who graduated from the Dental School, Cardiff, Wales, UK. The first part requested basic information regarding age, year of qualification, field of practice, etc. The second part consisted of 15 questions on endodontic practice and root canal treatment. RESULTS: The response rate was 41.5%. Two hundred and ninety-nine questionnaires contained useful information. The majority of practitioners did not use rubber dam during root canal treatment. The vast majority (89%) exposed a radiograph with an instrument of known length in situ to gauge the 'working length', a small number relied upon tactile sensation. Most practitioners used local anaesthetic solution as an irrigant during instrumentation of the root canal. A wide variety of instruments were used for root canal treatment; a stepback technique was preferred by almost half the practitioners. Antiseptic solution was preferred as an interappointment dressing. More than half of the respondents used laterally condensed gutta-percha to obturate root canals in anterior teeth but only one-third used the same technique in posterior teeth. Less than half the respondents exposed a radiograph to check the fit of the master point prior to obturation. Two-thirds of practitioners used a zinc oxide based material as their root canal sealer. Three-quarters of the practitioners exposed a post obturation radiograph. CONCLUSIONS: The results of this study suggest that although some dentists are using the techniques taught during their undergraduate careers, a large percentage now use techniques with no evidence of clinical effectiveness.

Adult↗
PubMed2001

Effects of endodontic instrument handle diameter on electromyographic activity of forearm and hand muscles.

AIM: To determine the influence of the handle diameter of endodontic instruments on forearm and hand muscle activity using electromyographic (EMG) recording. METHODOLOGY: Size 45 K-type files were fitted with four different handle diameters; 3.5, 4.0, 5.0, and 6.0 mm. Seven dentists then attempted to negotiate to the working length acrylic resin root canals with each of the four handle sizes using a reaming motion. EMG activities were recorded from the flexor pollicis brevis muscle (f.p.b.), the flexor carpi radialis muscle (f.c.r.), and the brachioradialis muscle (b) with bipolar surface electrodes. The time taken to negotiate the canals, the area of integrated EMG that corresponded to the amount of EMG activity required during penetration and the maximum amplitude of EMG were measured using the EMG data. Results were analysed statistically using a one-way factorial ANOVA test and multiple comparison tests. RESULTS: Reaming time and integrated EMG area of each muscle decreased with an increase in handle diameter. The most significant difference in time and area of integrated EMG was detected between handles of 6 mm and 3.5 mm diameter (time: P < 0.01, area of the f.p.b.: P < 0.01, area of the f.c.r. and b: P < 0.05), and between handles of 5 mm and 3.5 mm diameter (P < 0.05). Both 5 mm and 6 mm handles significantly decreased the maximum amplitude of EMG recorded from the f.p.b. compared with 3.5 mm handles (between 3.5 mm and 6 mm: P < 0.01, between 3.5 mm and 5 mm: P < 0.05). CONCLUSION: The results indicate that handle diameter has an effect on reaming time as well as on muscle activity. As a consequence, handle diameter influenced operator performance during instrumentation.

Acrylic Resins↗
PubMed2001

Polymerase chain reaction detection of Treponema denticola in endodontic infections within root canals.

AIM: A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect the occurrence of Treponema denticola in root canals. METHODOLOGY: Samples were collected from 54 single-rooted teeth having carious lesions and necrotic pulps. DNA extracted from the samples was amplified using the PCR assay, which yielded a specific fragment of T. denticola 16S rDNA. RESULTS: T. denticola was detected in 10 of 29 asymptomatic cases (34.5%), eight of 15 root canals that were tender to percussion (53.3%), and five of 10 teeth with acute periradicular abscess (50%). In general, T. denticola was found in 23 of 54 cases (42.6%). CONCLUSIONS: Findings suggest that T. denticola can be involved in the pathogenesis of periradicular lesions of endodontic origin.

Adolescent↗
PubMed2001

The histological effects of four endodontic sealers implanted in the oral mucosa: submucous injection versus implant in polyethylene tubes.

AIM: The aim of this study was to evaluate pigmentation and tissue response to four endodontic sealers placed in the oral mucosa of rabbits by either submucous injection or implant in polyethylene tubes. METHODOLOGY: Thirty white New Zealand rabbits were divided randomly into two groups of eight for N-Rickert and AH-26, and two groups of seven for Fillcanal and Sealer 2 6. On the right side of the filter, corresponding to the gingivo-labial sulcus in humans, the sealer was injected; on the left side the sealer was placed within a polyethylene tube and implanted. Direct clinical observations were made at 30, 60 and 90 days. The animals were then sacrificed for histological analysis. RESULTS: After 60 days of observation N-Rickert and AH-26 produced tattoos that became larger by 90 days. Submucous injection produced larger and more numerous pigmentation, when compared to implant in polyethylene tubes. N-Rickert sealer displayed larger and more numerous tattoos when compared to AH-26. Histological analysis showed no differences between the two methods of implantation. All sealers elicited some kind of inflammatory response; the most irritant was Fillcanal, followed by N-Rickert and AH-26. Sealer 26 elicited a mild reaction only. CONCLUSIONS: Under the conditions of this study there was no relationship between the method of implantation and the tissue response; the silver-containing sealers produced pigmentation, and the concentration of silver influenced the quantity and size of the tattoos. The sealers elicited various responses when in direct contact with the surrounding tissues: the calcium hydroxide-containing sealer had enhanced healing when compared to the other sealers.

Administration, Buccal↗
PubMed2001

Enterococcus faecalis--a mechanism for its role in endodontic failure.

AIM: The aim of this study was to identify a possible mechanism that would explain how E. faecalis could survive and grow within dentinal tubules and reinfect an obturated root canal. METHODOLOGY: Cells of Streptococcus gordonii DL1, Streptococcus mutans NG8, or E. faecalis JH2-2 were grown in brain heart infusion broth containing various amounts of human serum for 56 days. The ability of the three species to invade dentine and bind to immobilized type I collagen in the presence of human serum was assessed by dentine invasion and microtitre well experiments. RESULTS: All three species remained viable over the period of the experiment when grown in human serum. Cells of all three bacteria were able to invade dentine and bind to immobilized collagen. Both of these properties were inhibited by the presence of collagen in the cell solution. Human serum inhibited dentine invasion and collagen adhesion by S. gordonii DL1 and S. mutans NG8, whilst dentine invasion by E. faecalis JH2-2 was reduced in the presence of serum, but not inhibited, and binding to collagen was enhanced. CONCLUSIONS: It is postulated that a virulence factor of E. faecalis in failed endodontically treated teeth may be related to the ability of E. faecalis cells to maintain the capability to invade dentinal tubules and adhere to collagen in the presence of human serum.

Bacterial Adhesion↗
PubMed2002

Endodontic and periodontal treatments of a geminated mandibular first premolar.

AIM: To describe a rare case of gemination involving a mandibular first premolar. SUMMARY: The complex morphology of geminated teeth renders their endodontic and periodontal management difficult. Root canal and periodontal treatments were performed on a geminated mandibular first premolar with three canals. Clinical examination showed two separated crowns with united roots. Radiographically, two distinct pulp chambers with two joined and a third independent canal were seen. Conventional root canal treatment resulted in complete healing of the apical lesion. However, the occurrence of a vertical fracture led to the extraction of the mesial segment. At the follow-up visit, the distal segment was clinically healthy and continued to satisfy functional demands.

Adult↗
PubMed2002

A survey of methods used for post removal in specialist endodontic practice.

AIM: The aims of this study were to determine the attitudes of endodontists toward the risk of root fracture when removing posts and to determine which methods they commonly used to remove posts from root-filled teeth. METHODOLOGY: A survey was sent to all 74 members of the Australian and New Zealand Academy of Endodontists. The survey was divided into three parts to gather information concerning root canal retreatment performed in specialist endodontic practice, attitudes about the risk of root fracture when removing posts and the methods used to remove different post systems. RESULTS: Responses were received from 62 (84%) of the Academy members. When a post was present in a tooth that required root canal retreatment, 66% of the endodontists preferred to remove the post, whilst 27% considered either post removal or periapical surgery. Forty-five per cent reported that a root fracture had occurred during post removal, but this represented less than 0.002% of the estimated number of posts removed by all respondents. Ultrasonic vibration was the most common method used to remove posts, although post removal devices were used more often in anterior teeth; the Eggler post remover was the most commonly used device. CONCLUSIONS: Most endodontists preferred to remove posts rather than perform periapical surgery. Few root fractures were reported. Ultrasonic vibration was the most common method used to remove posts from all tooth types, with the Eggler post remover used most commonly for posts in anterior teeth.

Attitude of Health Personnel↗
PubMed2002

Periapical status, prevalence and quality of endodontic treatment in an adult French population.

AIM: The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998. METHODOLOGY: Patients who attended the dental school for the first time during 1998 were included. Panoramic radiographs, taken by a trained radiology assistant, were used in this study. The periapical areas of all teeth with the exception of third molars, were examined and the technical quality of root fillings were evaluated for both apical extension and density. Statistical analyses were conducted using anova, Chi-square, Fisher's PLSD and Cohen's Kappa tests. RESULTS: The survey involved 344 patients: 180 females and 164 males. Males had significantly fewer natural remaining teeth than females (P<0.03). Similarly, the average number of root-filled teeth was lower for males (P<0.01). Nonroot-filled teeth (n=6126) had significantly fewer signs of periapical pathology than root-filled teeth (n=1429) (1.7% vs. 31.5%, P<0.0001). The majority of root fillings were poorly executed. There was a significant correlation between the presence of periapical pathology and inadequate root-canal fillings (P<0.001). CONCLUSIONS: The results of the present study indicate that many root-canal treatments were technically unsatisfactory in terms of quality and treatment outcome. There is a need for endodontic retreatment in the population examined.

Adult↗