Accuracy of cold sensibility testing on teeth with full-coverage restorations: a clinical study.

AIM: This clinical study evaluated the reliability of the 1,1,1,2-tetrafluoroethane (Endo Ice) cold test to determine the pulpal diagnosis of teeth with full-coverage restorations (FCR). The effect of several variables on its reliability was also investigated. METHODOLOGY: Data collected from 825 patients treated in the Advanced Education Program in Endodontics at the University of Iowa, USA were analysed. The experimental group included 425 teeth with FCR, whilst the control group consisted of 400 teeth with natural crowns (NC). The pulp sensibility test results, tooth type, tooth number, type of crown, age, gender, presence or absence of caries and recent use of analgesics were recorded. Bivariate analyses were performed to assess the variables associated with the accuracy of dental pulp sensibility tests for either teeth with crowns or teeth without crowns using chi-square tests, Fisher's exact tests, Cochran-Mantel-Haenszel tests, and the Wilcoxon rank-sum tests. A P-value of less than 0.05 was used as a criterion for statistical significance, and a P-value in 0.05 < P < 0.10 was used as a criterion for marginal relevance. RESULTS: The sensibility test results for FCR teeth had an accuracy of 0.866; sensitivity of 0.835; specificity of 0.879; a positive predictive value of 0.746; and a negative predictive value of 0.926. The data indicated a significant difference in the accuracy of pulp sensibility test results between the experimental and control groups (P < 0.001). Although the cold test in FCR teeth still had high accuracy, teeth with NC were significantly more likely to have true-positive and true-negative results (91.5% NC vs. 86.6% FCR, P = 0.024). No significant differences between FCR and NC were found concerning gender, tooth type, type of crown, the presence of abutment and recent use of analgesic (P > 0.05). CONCLUSION: Pulp sensibility cold testing with 1,1,1,2-tetrafluoroethane (TFE) on teeth with FCR was less accurate than on teeth without full-coverage crowns. However, the use of TFE cold testing is still a relevant and reliable diagnostic tool, particularly for teeth with a pulpal diagnosis of symptomatic irreversible pulpitis. Clinicians should routinely carry out cold pulp sensibility testing on teeth when making a pulpal diagnosis.

Comparison of cone beam CT scans with enhanced photostimulated phosphor plate images in the detection of root fracture of endodontically treated teeth.

OBJECTIVES: Two-dimensional intraoral radiography is the most common tool for diagnosing root fractures (RFs). Cone beam CT (CBCT) is widely used to depict RFs in endodontically treated teeth. Beam hardening and other artefacts caused by gutta percha may result in an incorrect diagnosis when using CBCT only. A comparison of two CBCT machines with photostimulated phosphor (PSP) plate images enhanced with the equalization tool was carried out to detect RFs in endodontically treated teeth. METHODS: 66 roots were collected, decoronated and treated endodontically using the same technique with gutta percha. 33 of these roots were randomly selected and fractured; the 2 root fragments were glued together with 1 layer of methyl methacrylate and placed randomly in 8 prepared beef rib fragments. Large fields of view (FOVs) were acquired with one CBCT unit and small FOVs with the second CBCT unit. Periapical radiographs (using intraoral PSP plates) were also acquired. A contrast enhancement tool was used when evaluating the PSP plate images. RESULTS: Small FOV images had significantly higher accuracy (area under the receiver operating characteristic curve) and sensitivity in detecting RFs than PSP plates and large FOV images. The specificity of the enhanced PSP images was higher than, although not significantly higher than, the small FOV images and was significantly higher than the large FOV images. CONCLUSIONS: CBCT small FOVs should be acquired for depicting RFs of endodontically treated teeth. Images obtained using PSP plates had the lowest rate of false-positive results and their use can save the patient a radiation dose.

Cone beam CT scans with and without artefact reduction in root fracture detection of endodontically treated teeth.

OBJECTIVES: Cone beam CT (CBCT) is used widely to depict root fracture (RF) in endodontically treated teeth. Beam hardening and other artefacts due to gutta-percha may increase the time of the diagnosis and result in an incorrect diagnosis. Two CBCT machines, ProMax(®) (Planmeca, Helsinki, Finland) and Master 3D(®) (Vatech, Hwaseong, Republic of Korea), have the option of applying an artefact reduction (AR) algorithm. The aim of this study was to determine whether using an AR algorithm in two CBCT machines enhances the accuracy of detecting RFs in endodontically treated teeth. METHODS: 66 roots were collected and decoronated. All roots were treated endodontically using the same technique with gutta-percha and zinc oxide cement. One-half of the roots were randomly selected and fractured using a nail that was tapped gently with a hammer until complete fracture resulted in two root fragments; the two root fragments were glued together with one layer of methyl methacrylate. The roots were placed randomly in eight prepared beef rib fragments. RESULTS: The highest accuracy was obtained when the ProMax was used without AR. The lowest accuracy was obtained with the Master 3D when used with AR. For both machines, accuracy was significantly higher without AR than with AR. Both with and without AR, the ProMax machine was significantly more accurate than the Master 3D machine. The same rank ordering was obtained for both sensitivity and specificity. CONCLUSIONS: For both machines, AR decreased the accuracy of RF detection in endodontically treated teeth. The highest accuracy was obtained when using the ProMax without AR.

Morphology of the dentin structure of sloths Bradypus tridactylus: a light and scanning electron microscopy investigation.

The aim of this study was to describe the dentine morphology of sloths (Bradypus tridactylus). The sloth teeth were removed and prepared for light microscopy (LM) and scanning electron microscopy analyses (SEM). LM revealed two patterns of tubular dentins: an outer with dentinary tubules over the all tooth length and one in the inner part with larger diameter and more spaced tubules, when compared to those present in the outer dentine. These findings were confirmed by SEM, which revealed a tubular pattern in the outer dentine like in humans. The inner dentine displayed pared grouped tubules that were characterized as vascular channels. It can be concluded that this sloth species present two types of dentins: an inner dentin (ortodentin) and an outer dentin characterized as a vascular dentin. This suggests a partial evolutive/adaptive process of this dental tissue, as compared to other mammalian species.

The effect of intracanal anti-inflammatory medicaments on external root resorption of replanted dog teeth after extended extra-oral dry time.

The prognosis of replanted teeth depends on several factors, the most important being the length of extra-oral dry time. Studies show that after 60 min dry time, root resorption is predicted. Immediate intracanal placement of Ledermix, a paste containing triamcinolone (corticosteroid) and demeclocycline (tetracycline) has been shown to inhibit root resorption after extended dry time. However, discoloration is possible from the tetracycline in Ledermix. To evaluate the individual influence of corticosteroid and tetracycline on external root resorption after extended extra-oral dry time. Sixty-nine premolar roots of four beagle dogs were extracted and instrumented with NiTi files. Group 1 (negative control) was immediately replanted after root filling with GP and sealer; Group 2 (positive control) was root filled with GP and sealer and replanted after 60 min dry time; In groups 3-5, the canals were filled with Ledermix, Triamcinolone, and Demeclocycline, respectively, and replanted after 60 min dry time. After 4 months, the dogs were sacrificed and the roots were examined histologically for type of healing (favorable or unfavorable) and remaining root diameter. The groups treated with Ledermix, Triamcinolone and Demeclocycline had statistically significantly more favorable healing (75.8%; 69.8%; 52.4%) and more remaining root structure (5.59; 5.48; 5.09) than the group filled with GP and sealer (positive control) (0; 1.15). Corticosteroids were as effective as Ledermix at inhibiting external root resorption.

Assessment of different gutta-percha brands during the filling of simulated lateral canals.

AIM: To compare the ability of five different commercially available gutta-percha points to fill simulated lateral canals when subjected to warm vertical compaction. METHODOLOGY: Fifty clear plastic teeth with a lateral canal in each third of the root were used. All teeth were filled using warm vertical compaction. Backfilling was completed with a sealer and the same gutta-percha point used during the apical condensation. After this, they were horizontally sectioned using a diamond disc adapted to a low-speed saw. The resulting sections were embedded in epoxy resin. The extent of gutta-percha and sealer filling were measured in each lateral canal using an IMAGE-PRO 4.0 software system. The voids in each canal were measured using the same system. Data were ranked and analysed using the Kruskal-Wallis statistical test. RESULTS: The mean percentage of the three lateral canals filled with gutta-percha and sealer were respectively: Konne (68.23% and 24.50%), Analytic (67.90% and 25.28%), Obtura (63.80% and 29.60%), Tanari (49.42% and 45.86%) and Dentsply (44.60% and 47.05%). There was significantly (P < 0.05) more gutta-percha in the lateral canal filled with Analytic, Obtura and Konne points than with Tanari and Dentsply points. CONCLUSIONS: The brand of gutta-percha cone had an influence on the length of filling within lateral canals. This may be a reflection of the chemical formulation of the gutta-percha points.

Microbiological examination of infected dental root canals.

OBJECTIVES: The aim of this study was to investigate the root canal microbiota of primary and secondary root-infected canals and the association of constituent species with specific endodontic signs and symptoms. METHODS: Microbial samples were taken from 60 root canals, 41 with necrotic pulp tissues (primary infection) and 19 with failed endodontic treatment (secondary infection). Strict anaerobic techniques were used for serial dilution, plating, incubation and identification. RESULTS: A total of 224 cultivable isolates were recovered belonging to 56 different bacterial species. Individual root canals yielded a maximum of 10 bacterial species. Of the bacterial isolates, 70% were either strict anaerobes or microphilic. The anaerobes most frequently isolated were: Peptostreptococcus micros (35%), Fusobacterium necrophorum (23.3%), Fusobacterium nucleatum (11.7%), Prevotella intermedia/nigrescens (16.7%), Porphyromonas gingivalis (6.7%) and Porphyromonas endodontalis (5%). The root canal microflora of untreated teeth with apical periodontitis was found to be mixed, comprising gram-negative and gram-positive and mostly anaerobic microorganisms and usually containing more than 3 species per canal. On the other hand, facultative anaerobic and gram-positive bacteria predominated in canals with failed endodontic treatment, which harbored 1-2 species per canal. Suggested relationships were found between anaerobes, especially gram-negatives, and the presence or history of pain, tenderness to percussion and swelling (P<0.05). In particular, associations were found between: a) pain (n=29) and P. micros (P<0.01), P. intermedia/nigrescens and Eubacterium spp. (both P<0.05); b) history of pain (n=31) and P. micros (P<0.01) Porphyromonas and Fusobacterium spp. (P<0.05); c) tenderness to percussion (n=29) and Porphyromonas spp. (P<0.01), Peptostreptococcus and Fusobacterium spp. (P<0.001); d) swelling (n=20) and Peptostreptococcus spp. (P<0.01), Porphyromonas and Enterococcus spp. (P<0.05); e) wet canals (n=33) and Porphyromonas and Fusobacterium spp. (P<0.05); f) purulent exudate (n=20) and Porphyromonas, Peptostreptococcus and Fusobacterium spp. (P<0.05); previous endodontic treatment and Enterococcus faecalis, Streptococcus spp., P. micros, F. necrophorum (P<0.05). CONCLUSIONS: Our findings indicate potential complex interactions of species resulting in characteristic clinical pictures which cannot be achieved by individual species alone. They also indicate that the microbiota of primary infected canals with apical periodontitis differs in number and in species from the secondary infected canals by using the culture technique.

Evaluation of time required for recontamination of coronally sealed canals medicated with calcium hydroxide and chlorhexidine.

AIM: To determine in vitro the time required for recontamination of coronally sealed canals medicated with either calcium hydroxide (CaOH2), 2% chlorhexidine gel (CG) or with a combination of both. METHODOLOGY: Eighty intact, caries-free, premolar teeth with straight roots and mature apices were selected for the study. After biomechanical preparation of 75 teeth, they were randomly divided into nine groups according to the intracanal medicament and the coronal seal with 'Intermediate Restorative Material' (IRM) as follows: (i) 10 teeth medicated with CG, coronally unsealed; (ii) 10 teeth medicated with CaOH2, coronally unsealed; (iii) 10 teeth medicated with CaOH2 + CG, coronally unsealed; (iv) 10 teeth medicated with CG + coronal seal; (v) 10 teeth medicated with CaOH2 + coronal seal; (vi) 10 teeth medicated with CG + CaOH2 + coronal seal; (vii) 10 teeth without intracanal medicament and coronally sealed; (viii) 5 teeth without intracanal medicament and coronally unsealed, used as the positive control group (PC); (ix) 5 teeth with intact crowns used as the negative control group (NC). Glass flasks were filled with Brain Heart Infusion broth (BHI), so that only the root apex was in contact with the broth, while the crown was immersed in human saliva + BHI (3:1). The flasks were then incubated at 37 degrees C in an atmosphere of 10% CO2, and microbial growth was checked daily. RESULTS: All specimens of the PC showed contamination within 1 day of incubation, while the NC showed no evidence of broth turbidity. Recontamination was detected after an average time of 3.7 days in the unsealed canals medicated with CG, 1.8 days in the group medicated with CaOH2 and 2.6 days in the group medicated with CaOH2 + CG. When the crowns were sealed with IRM, recontamination was detected within 13.5 days in the canals medicated with CG, after 17.2 days in the group medicated with CaOH2 and after 11.9 days in the group medicated with CG + CaOH2. The group with no medication, but sealed with IRM, showed recontamination after 8.7 days. There were statistically significant differences between the teeth with or without coronal seal (P<0.05). CONCLUSION: The coronal seal delayed but did not prevent leakage of microorganisms. There was no difference between the various medicaments.

Investigation of the marginal adaptation of root-end filling materials in root-end cavities prepared with ultrasonic tips.

AIM: To compare the surface topography of root apices following ultrasonic root-end preparation, and again after root-end fillings submitted to three different finishing techniques. METHODOLOGY: Eighty-one root-end cavities prepared ultrasonically in human canines, were divided at random into three test groups of 27 each. The cavities were filled with Super-EBA, IRM, or ProRoot-MTA and finished by ball burnishing. Eighteen roots from each group received a final finish with either a 30-fluted tungsten carbide finishing bur, or a Zekrya carbide 28 mm bur after storage in water at 37 degrees C for 24 h. The root-end surface topographies were reproduced by means of polyvinylsiloxane impressions and epoxy resin replicas. Scanning electron micrography (SEM) images of each replica were taken prior to and after root-end filling. An image analysis system was used to compare the alteration of the marginal chipping areas and to calculate the gaps located in the dentine/root-end filling interface. RESULTS: When a bur was used to finish the set materials, a significant (P < 0.05) area of marginal chipping was eliminated. The finishing technique did not significantly (P > 0.05) affect the incidence of gaps in groups root-end filled with MTA or IRM. Super-EBA and IRM retrofillings finished with a ball burnisher or a Zekrya bur displayed a significantly (P < 0.05) larger calculated gap area than roots filled with MTA. CONCLUSION: Under this in vitro study, the marginal adaptation of MTA was good with or without finishing procedures. Applying a finishing bur over the condensed and set IRM and Super-EBA created better marginal adaptation.

Effectiveness of 2% chlorhexidine gel and calcium hydroxide against Enterococcus faecalis in bovine root dentine in vitro.

AIM: To evaluate the effectiveness of 2% chlorhexidine gluconate gel and calcium hydroxide (Ca(OH)2) as intracanal medicaments against Enterococcus faecalis. METHODOLOGY: One hundred and eighty dentine tubes prepared from intact freshly extracted bovine maxillary central incisors were infected in vitro for 7 days with E. faecalis. The specimens were divided into four groups, according to the intracanal medicament used, as follows: Group 1: 2% chlorhexidine gluconate gel; Group 2: calcium hydroxide in a viscous vehicle (polyethyleneglycol 400); Group 3: 2% chlorhexidine gluconate gel + calcium hydroxide and Group 4: Brain Heart Infusion (BHI) broth (control group). The medicaments were placed into the canal lumen and left there for experimental times of 1, 2, 7, 15 and 30 days. After each period, irrigation with sterile saline to remove the medicament was performed and the canals were dried with sterile paper points. Dentine chips were removed from the canals with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing BHI broth. The tubes were incubated at 37 degrees C and daily observed for microbial growth, visualized by the medium turbidity. RESULTS: Chlorhexidine gel alone completely inhibited the growth of E. faecalis after 1, 2, 7 and 15 days. Calcium hydroxide allowed microbial growth at all experimental times. The combination of chlorhexidine and Ca(OH)2 was effective after 1 and 2 days demonstrating 100% antibacterial action; however, its antibacterial activity reduced between 7 and 15 days. CONCLUSION: Under the conditions of this study, it can be concluded that 2% chlorhexidine gel alone was more effective against E. faecalis than calcium hydroxide (P < 0.05). However, its antibacterial activity depended on how long it remained inside the root canal.

A preliminary in vitro study of the incidence and position of the root canal isthmus in maxillary and mandibular first molars.

AIM: To investigate in vitro the incidence and position of the root canal isthmus in extracted mesiobuccal roots of maxillary and mesial roots of mandibular first molars. METHODOLOGY: Fifty maxillary and 50 mandibular molars were included in the study. The mesiobuccal roots of maxillary molars and the mesial roots of mandibular molars were sectioned from their crowns in the furcation region and embedded in clear resin. Transverse serial 1-mm-thick sections from the apical 6 mm were prepared. The apical side of each section was stained with India ink and observed through a light microscope. The sample images were saved to disk using a digital camera and the root canals in terms of the number present and the incidence and classification of isthmuses. RESULTS: In the mesiobuccal root of the maxillary first molars, 70% had one canal, whereas 29.5% had two canals. In the mesial root of mandibular molars, 41% had one canal, whereas 59% had two canals. In some sections, more than two canals were found close to the apical foramen. The isthmus incidence was greatest 3-5 mm from the apex. In teeth having two canals, a complete or partial isthmus was frequently observed in the sections between 3 and 4 mm from the apex. Of the isthmuses present, 22% were complete and 37% partial in mandibular molars and 17.3% were complete and 11.7% partial in maxillary molars. CONCLUSIONS: The incidence of isthmus in the mesiobuccal root of the maxillary first molars and in the mesial root of the mandibular first molars was high, particularly in sections 3-5 mm from the apex. Cleaning the isthmus is a major challenge during root canal treatment.

Chemical and X-ray analyses of five brands of dental gutta-percha cone.

AIM: To determine the chemical composition of five commercially available nonstandardized gutta-percha points. METHODOLOGY: The organic fraction (gutta-percha polymer and wax/resin) of nonstandardized gutta-percha points (Dentsply, Tanari, Konne, Obtura Spartan and Analytic Endodontics) was separated from the inorganic fraction (ZnO and BaSO4) by dissolution in chloroform. Gutta-percha polymer was precipitated with acetone. Zinc oxide was partially separated from barium sulphate by reaction with HCl. Energy-dispersive X-ray microanalysis and X-ray diffraction were employed to identify the chemical elements and compounds (barium sulphate and zinc oxide). The barium sulphate content was calculated by percentage of sulphur from elemental microanalysis. All analyses were repeated three times. RESULTS: The means and standard deviations of the percentage by weight of gutta-percha in the points were: Dentsply (14.5 +/- 0.70%), Tanari (15.6 +/- 0.66%), Obtura (17.7 +/- 0.35%), Konne (18.9 +/- 0.32%) and Analytic (20.4 +/- 0.40%). The mean and SD of the zinc oxide content were: Dentsply (84.3 +/- 0.50%), Tanari (82.0 +/- 0.72%), Obtura (69.5 +/- 0.21%), Konne (78.0 +/- 0.05%) and Analytic (66.5 +/- 0.50%). CONCLUSIONS: The method was appropriate to quantify gutta-percha and resin/wax components of gutta-percha points, but not barium sulphate and zinc oxide. An alternative procedure to determine barium sulphate and zinc oxide contents has been proposed based on elemental microanalysis of sulphur. Some brands of gutta-percha did not contain barium sulphate.

Microorganisms from canals of root-filled teeth with periapical lesions.

AIM: The objective of the present study was to identify the microbial flora within root canals of teeth with failed root-canal treatment and to determine the association of the various species with clinical features. METHODOLOGY: Sixty root-filled teeth with persisting periapical lesions were selected for this study. During nonsurgical endodontic re-treatment, the root-filling material was removed and the canals were sampled. Microbial sampling, isolation and species determination were performed using advanced microbiological techniques for anaerobic species. The association of microbiological findings with clinical features was investigated. RESULTS: Microorganisms were recovered from 51 teeth. In most cases, one or two strains per canal were found. Of the microbial species isolated, 57.4% were facultative anaerobic species and 83.3% Gram-positive microorganisms. Enterococcus faecalis was the most frequently recovered bacterial species. Obligate anaerobes accounted for 42.6% of the species and the most frequently isolated genera was Peptostreptococcus. which was associated with clinical symptoms (P < 0.01). Significant associations were also observed between: (a) pain or history of pain and polymicrobial infections or anaerobes (P < 0.05): (b) tenderness to percussion and Prevotella intermedia/P. nigrescens (P < 0.05); (c) sinus and Streptococcus spp. (P < 0.001) or Actinomyces spp. (P < 0.01); (d) coronally unsealed teeth and Streptococcus spp. or Candida spp. (both with P < 0.01). CONCLUSION: The microbial flora in canals after failure of root-canal treatment were limited to a small number of predominantly Gram-positive microbial species. Facultative anaerobes, especially E. faecalis, were the most commonly isolated microorganisms, however, polymicrobial infections and obligate anaerobes were frequently found in canals of symptomatic root-filled teeth.

Evaluation of root canal microorganisms isolated from teeth with endodontic failure and their antimicrobial susceptibility.

Studies of the microbiota from the canals of teeth with failure of endodontic therapy have revealed that it differs markedly from that of untreated necrotic dental pulps. This study aimed to evaluate the microbiota of 30 root-filled teeth with persisting periapical lesions and to test the antibiotic susceptibility of the most prevalent species. Microbial samples, isolation and speciation were done using advanced microbiologic techniques for anaerobic species. A total of 55 bacterial species were isolated, 80% were gram-positives and 58% facultative anaerobic microorganisms. The bacterial genera most frequently recovered were Enterococcus, Streptococcus, Peptostreptococcus and Actinomyces. Antibiotic sensitivity of Enterococcus faecalis and Peptostreptococcus spp. was accomplished with the E-test system. All species studied were susceptible to benzylpenicillin, amoxicillin, amoxicillin combined with clavulanate. However, 20% of the E.faecalis strains were resistant to erythromycin and 60% to azithromycin. It was concluded that microbial flora in canals after endodontic failure comprised predominantly facultative anaerobes and gram-positive species. E.faecalis was the species most frequently isolated and showed erythromycin and azithromycin resistance among the isolates.

An in vitro evaluation of four materials as barriers to coronal microleakage in root-filled teeth.

AIM: To assess the ability of IRM, Coltosol, Vidrion R and Scotch Bond to seal the pulp chamber following root-canal treatment. METHODOLOGY: Root-canal treatment was completed on 100 extracted human mandibular molars. The teeth were divided into five groups of 20 teeth each, one group for each barrier material and one control group without barrier material. Two millimetres of the restorative material was placed on the pulp chamber floor. The teeth were thermocycled and evaluated for microleakage using India ink. Specimens were cleared and measurements made to the maximum point of dye penetration. The mean dye penetration for each group was compared by the Kruskal-Wallis test. RESULTS: All groups showed dye penetration. Coltosol and IRM sealed significantly better than the other groups, preventing the coronal leakage in 84% and 75% of the specimens, respectively. Scotch Bond exhibited the highest leakage (54% of specimens with dye penetration), which did not differ significantly from the positive control group (62% with dye penetration). CONCLUSIONS: None of the materials were able to prevent microleakage in all specimens. Vidrion R and Scotch Bond demonstrated the poorest results when used as barriers to coronal microleakage, whilst IRM and Coltosol were significantly better in preventing microleakage.

Influence of irrigants on the coronal microleakage of laterally condensed gutta-percha root fillings.

AIM: To assess in vitro coronal microleakage in extracted human teeth after root-canal treatment, using different endodontic irrigants. METHODOLOGY: Fifty teeth with single root canals were prepared and filled using the lateral condensation of gutta-percha and Endométhasone sealer. Canal preparation consisted of initial shaping of the coronal two-thirds with Gates-Glidden burs size 2 and 3, followed by preparation of the apical stop and step-back flaring with manual files. Each group (n = 10) was irrigated with the following solutions: I--1% NaOCl, II--1% NaOCl + 17% EDTA, III--2% chlorhexidine gel, IV--2% chlorhexidine gel + 1% NaOCl, and V--distilled water. After root-canal filling, the teeth were incubated at 37 degrees C for 10 days followed by 10 days immersion in human saliva and an additional 10 days in India ink. The teeth were cleared and maximum dye penetration was determined digitally in millimetres. Statistical analysis was carried out using the Kruskal-Wallis test. RESULTS: Least leakage occurred with 1% NaOCl + 17% EDTA (2.62 mm) and 2% chlorhexidine gel (2.78 mm) (P > 0.05). NaOCl (3.51 mm), distilled water (6.10 mm) and 2% chlorhexidine gel + 1% NaOCl (9.36 mm) gave increased leakage with a significant difference compared to NaOCl + 17% EDTA and 2% chlorhexidine gel, and compared to one another (P < 0.05). CONCLUSIONS: Under the condition of this study, irrigation method during root-canal treatment influenced coronal microleakage. NaOCl + EDTA and chlorhexidine gel allowed better sealing following root filling.

In vitro antimicrobial activity of several concentrations of sodium hypochlorite and chlorhexidine gluconate in the elimination of Enterococcus faecalis.

AIM: The aim of this study was to assess, in vitro, the effectiveness of several concentrations of NaOCl (0.5%, 1%, 2.5%, 4% and 5.25%) and two forms of chlorhexidine gluconate (gel and liquid) in three concentrations (0.2%, 1% and 2%) in the elimination of E. faecalis. METHODOLOGY: A broth dilution test using 24-well cell culture plates was performed and the time taken for the irrigants to kill bacterial cells was recorded. Isolated 24 h colonies of pure cultures of E. faecalis grown on 10% sheep blood plus Brain Heart Infusion (BHI) agar plates were suspended in sterile 0.85% NaCI solution. The cell suspension was adjusted spectrophotometrically to match the turbidity of a McFarland 0.5 scale. One mL of each tested substance was placed on the bottom of wells of 24-well cell culture plates (Corning, NY), including the control group (sterile saline). Six wells were used for each time period and irrigant concentration. Two mL of the bacterial suspension were ultrasonically mixed for 10 s with the irrigants and placed in contact with them for 10, 30, and 45 s; 1, 3, 5, 10, 20, and 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared BHI + neutralizers in order to prevent a residual action of the irrigants. All tubes were incubated at 37 degrees C for 7 days. The tubes considered to have positive growth were those which presented medium turbidity during the incubation period. Data were analysed statistically by the Kruskal-Wallis test. with the level of significance set at P < 0.05. RESULTS: All irrigants were effective in killing E. faecalis. but at different times. Chlorhexidine in the liquid form at all concentrations tested (0.2%, 1% and 2%) and NaOCI (5.25%) were the most effective irrigants. However, the time required by 0.2% chlorhexidine liquid and 2% chlorhexidine gel to promote negative cultures was only 30 s and 1 min, respectively. CONCLUSIONS: Even though all tested irrigants possessed antibacterial activity, the time required to eliminate E. faecalis depended on the concentration and type of irrigant used.

In vitro assessment of the antimicrobial action and the mechanical ability of chlorhexidine gel as an endodontic irrigant.

The objective of this study was to assess the chlorhexidine gluconate gel as an endodontic irrigant. First the ability of chlorhexidine gel to disinfect root canals contaminated in vitro with Enterococcus faecalis was investigated. A scanning electron microscope was also used to evaluate its cleansing ability compared with endodontic irrigants commonly used, such as sodium hypochlorite and chlorhexidine gluconate liquid. The results indicated that the chlorhexidine gel produced a cleaner root canal surface and had an antimicrobial ability comparable with that obtained with the other solutions tested. It was concluded that chlorhexidine gluconate in gel form has potential for use as an endodontic irrigant.

Apical extrusion of debris and irrigants using two hand and three engine-driven instrumentation techniques.

AIM: To evaluate the weight of debris and irrigant volume extruded apically from extracted teeth in vitro after endodontic instrumentation using the balanced force technique, a hybrid hand instrumentation technique, and three engine-driven techniques utilizing nickel-titanium instruments (ProFile .04, Quantec 2000 and Pow-R). METHODOLOGY: Five groups of 20 extracted human teeth with single canals were instrumented using one or other of five techniques: balanced force, hybrid, Quantec 2000, ProFile .04, or Pow-R. Debris extruded from the apical foramen during instrumentation were collected into preweighed 1.5 mL tubes. Following instrumentation, the volume of extruded irrigant fluid was determined by visual comparison to control centrifuge tubes filled with 0.25 mL increments of distilled water. The weight of dry extruded dentine debris was also established. RESULTS: Overall, the engine-driven techniques extruded less debris than the manual ones. However, there was no statistical difference between the balanced force technique and the engine-driven methods. The volume of irrigant extruded through the apex was directly associated with the weight of extruded debris, except within the ProFile group. The hybrid technique was associated with the greatest extrusion of both debris and irrigant. CONCLUSIONS: Overall, the engine-driven nickel-titanium systems were associated with less apical extrusion.

Radiographic analysis of the development of periapical lesions in normal rats, sialoadenectomized rats and sialoadenectomized-immunosuppressed rats.

The purpose of this study was to investigate and to compare radiographically the development of periapical lesions in the lower left first molar of normal rats, sialoadenectomised rats and sialoadenectomised-immunosuppressed rats. Sixty male Wistar rats, weighing from 170 to 200 g were utilized. The animals were divided equally into three groups: group I--20 normal rats; group II--20 sialoadenectomised rats; and group III--20 sialoadenectomised-immunosuppressed rats. Groups II and III were sialoadenectomized using the modified Cheyne technique. After 2 weeks, group III was submitted to a immunosuppression regimen by daily subcutaneous cyclosporin A injection (10 mg/kg body weight). After 1 week of immunosuppression for this group, the pulps of all the animals (group I, II and III) were exposed to the oral cavity, to produce apical periodontitis. Five animals of each group were killed 7, 14, 21 and 28 days after pulpal exposure. Their mandibles were surgically removed and radiographically analysed. The lesions were measured using 'Global Lab Image' software. The results showed predictable growth of the lesions during the experimental period. No significant difference was observed between the groups. It was concluded that possible changes in the oral flora and in the host immune response due to xerostomia associated or not to the immunosuppression did not alter the development of the periapical lesions in rats.