The purpose of this study was to examine the effect of immersion in sodium hypochlorite on nickel titanium rotary files and determine whether resistance to fracture was influenced by the immersion time. 70 ISO size 25 0.04 taper nickel titanium K3 and Profile rotary instruments were immersed in 5.25% sodium hypochlorite for 1, 5, 15, 30, 60, and 120 minutes (n=5 each). Resistance to fracture was tested by rotating files at a 30 degree angle at 350 rpm in a universal testing machine. Time to fracture was recorded and analyzed by a two-way ANOVA. Within both file types, there was a decreased time to fracture with increased immersion time in sodium hypochlorite. K3 files required an average of 327 rotations to fracture, while Profiles required 420 rotations to fracture. Profiles required significantly more rotations to failure than K3 files.

The purpose of this study was to quantitatively compare the fill density of MTA produced by hand condensation and hand condensation with indirect ultrasonic activation. Thirty acrylic block with 30 degree curved canals (group C) and 30 with straight canals (group S) were instrumented to a final apical size of 45 of 0.06 taper crown-down technique. After irrigating with water and drying with paper points, each block was weighed to the nearest 0.0001g with a digital electronic balance. In half of the specimens, chosen at random, the canal first filled with MTA using the hand condensation method (H) then weighed. The MTA was removed. The canal was rinsed, dried, and refilled using hand condensation with indirect ultrasonic activation (US). In the other half of the specimens, the procedure was carried out identically but in reverse order. The blocks were weighed again after cleaning the MTA from the canal as well as after refilling the canal using indirect ultrasonic condensation. Data comparing the weight of MTA between the two placement methods and the two canal configurations were analyzed by a two-way ANOVA. There was a statistically significant increase in weight of MTA produced by ultrasonic activation than by hand condensation in groups C (p<.0001) and S (p<.0001). However, there was no statistically significant difference when comparing the straight canal versus the 30-degree curved canal (p = .08). In group C, ultrasonic condensation resulted in a 10.07% increase in the weight of MTA over hand condensation alone. Similarly in group S, there was a 9.1% increase in the weight of MTA over hand condensation. In conclusion, hand condensation with indirect ultrasonic activation resulted in an MTA fill that was denser than that accomplished by hand condensation alone.

The purpose of this study was to compare the density of gutta percha following three different obturation techniques using two split-tooth models. One split-tooth model was constructed with a straight rooted maxillary incisor and the other with the curved palatal root of a maxillary molar. Each tooth was obturated using single cone, cold lateral, and warm vertical obturation techniques without sealer. Each obturation technique was performed 20 times for each of the root systems. The weights of the gutta percha were recorded for each root type and obturation technique by subtracting the post-fill weight from the pre-fill weight of the two split-tooth models. Results show that in the straight canal, the three obturation techniques are significantly different (p < 0.0001). The warm vertical technique had the largest weight of gutta percha, followed by the single cone, and lastly by the cold lateral condensation group. In the curved canal, the three fill types were also significantly different (p < 0.0001). The warm vertical and single cone obturation techniques were not significantly different from one another but were significantly greater in gutta percha weight than the cold lateral technique. In conclusion, within curved canals, warm vertical and single cone techniques were more dense than cold lateral condensation. In the straight canal, the warm vertical was more dense than the single cone which was more dense than the cold lateral technique.

The purpose of this study was to compare the number of rotations to failure of three different rotary file systems. ProFile, Sequence, and Liberator files in sizes 25 and 40 with 0.04 taper were divided into groups of five and rotated against a grooved metal block mounted to a Universal testing machine at 31 and 34 degrees. Each file was rotated at 300 rpm until fracture occurred. The number of rotations to fracture were calculated. Use of a three-way ANOVA and Tukey's HSD multiple comparison tests revealed significant differences for the angle of deflection, size, and type of file. An increased angle of deflection resulted in a decreased number of rotations to failure for all three file types. An increased size of file also resulted in a decreased number of rotations to failure in all the groups. Liberator and Sequence files required fewer rotations to failure than ProFiles in all groups tested except the size 25 files rotated at the less severe angle. ProFiles appear to be more resistant to flexural fracture than Liberator and Sequence files unless the files are of smaller size with a less severe curvature. Care should be taken to limit the number of uses when using larger size files, especially Liberator and Sequence files, around severe curvatures.

The purpose of this study was to test the predictive ability of specific questions in diagnosis of pulpal and periradicular disease in a dental school population. 210 patients were recruited to fill out a questionnaire, and undergo a clinical examination for pulpal and/or periradicular disease.The Questionnaire asked if the patient had in the last 6 months: 1. a toothache that kept them up at night 2. a toothache that required pain killers 3. facial swelling caused by a tooth 4. injury to any teeth 5. a broken tooth 6. a tooth darker in color than the surrounding teeth 7. a bump, pimple, or boil on the gums. 8. a toothache after eating or drinking something hot or cold 9. repeated sharp pain in the same area while chewing 10. A toothache or facial swelling that caused them to visit an emergency room.Examiners were blinded to the responses on the questionnaire and then, based on the clinical examination and testing, determined the presence or absence of endodontic disease. The data was analyzed using univariate logistic regression models.Results: The most predictive questions were #1 and #2 (p-value Conclusion: Patients with pain that wakes them at night or that requires analgesics were greater than 3 times more likely to have endodontic disease at the time of examination.

Mature dendritic cells (DCs) in inflamed tissues may promote inflammation but the status of DCs in pulpitis is not known. We hypothesized that DC maturation would correlate with carious lesion depth and that CD4+ cells would be found in association with mature DCs. Pulps were collected from teeth exhibiting: (I) no caries (n=9), (II) shallow dentinal caries (n=5), and (III) deep caries (n=9). Pulpal tissues were cryo-sectioned and positive cells were examined with immunohistochemistry, Mature DCs (CD83+) were almost exclusively restricted to pulps from deep caries. Furthermore, CD209+ DCs in deep caries were elevated over other groups and CD209+ cells about doubled the CD83+ cells suggesting that immature DCs had accumulated and were available for terminal maturation. CD4+ cells were found associated with both mature DCs and macrophages in pulps from deep caries suggesting that T cells may be a source of pro-inflammatory cytokines at this inflamed site. This document was created in Microsoft Word 2000.

The purpose of this study was to determine whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution would affect the apical seal of three root canal cements. One hundred extracted human single-canal teeth were divided into 9 experimental groups of 10 teeth each, in addition to a positive and negative control group of 5 teeth each. The teeth were decoronated at the level of the cementoenamel junction, accessed, instrumented to a Master Apical File #50, irrigated with either sterile saline, 5.25% NaOCl or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and one of three endodontic sealers: Roth's 811, AH26, or Sealapex. Post-obturation apical leakage was measured at 270- and 360-day observation periods using the fluid filtration method. Using the mixed-model repeated-measures ANOVA test with Tukey's HSD multiple comparison procedure, the results showed the saline-Sealapex combination had significantly more leakage (p<0.05) than either the Peridex-Sealapex or saline-Roth's combinations at 270 days. No other significant differences were noted between any sealer-irrigant combination at 270 days. The saline-Sealapex combination had significantly more leakage than the saline-Roth's combination at 360 days. No other significant differences were noted at 360 days. Under the conditions of this study, chlorhexidine gluconate irrigant did not adversely affect the apical seal of three root canal cements at 270 and 360 days.

The objective of this study was two-fold: 1) to determine the accuracy of the Elements Apex Locator and 2) to compare the accuracy of the alginate and Endo Q models as in-vitro apex locator testing devices. Twenty teeth were decoronated at the CEJ and triplicate measurements were made using the Elements Apex Locator. All measurements were made to the apex reading of the apex locator. True length was established by visualizing the file tip at the apex with a dental operating microscope. Measurements were then taken with the teeth mounted in an alginate model and then in the Endo Q model. The two models were compared using a repeated-measure ANOVA. Statistically significant differences occurred between the alginate and Endo Q models. The results showed that in 95% (n=19) of the cases, an accurate location to within + 0.5 mm of the apical foramen was obtained with the Endo Q model and 55% (n=11) with the alginate model. With a + 1.0 mm tolerance level, an accuracy of 95% (n=19) was found with the use of the alginate model. In conclusion, it seems that the Endo Q system was more suitable for testing the electronic apex locator than the alginate model. The Elements Apex Locator with the use of the Endo Q model was highly accurate in locating to within + 0.5 mm of the apical foramen (Mean deviation = .17 mm).

Rotary endodontic instruments have different cross sectional designs that may effect their resistance to torsional stress. The purpose of this study is to evaluate the static torsional properties of two nickel titanium files that have recently been introduced for use in endodontics and compare them to the same size Profile instruments. Ten new files of each brand and size were tested. The files tested were: RaCe 25 tip 0.02, 0.04, 0.06 taper, K3 and Profile 25 and 40 tip in 0.02, 0.04 and 0.06 taper. The diameter of each file was measured at 3mm from tip. The last three millimeters of the working area of the file was grasped with a non-rotating stainless steel chuck and the handle was held in freely rotating chuck. Torque was applied with the Instron Universal Tester in a counter-clockwise direction to simulate the direction of torque encountered clinically. The crosshead speed was set to produce 2 rotations per minute until fracture occurred. The maximum torque achieved and the rotations to fracture were recorded. A multi-way ANOVA of rotations revealed that RaCe 25-0.02 exhibited significantly less rotations to fracture than Profile and K3 of the same size (p<0.0001). RaCe 25 tip exhibited lower maximum torque in all tapers than corresponding K3 and Profile instruments. The mean diameter was significantly smaller for the RaCe files. In this study the RaCe file series exhibited lower values for maximum torque and rotations to fracture. These results should be taken into account while using these files clinically, however further testing is indicated.

The purpose of this study was to determine if the viscosity of MTA Angelus Fluid is lower than that of Pro Root MTA and MTA Angelus; and to compare the viscosity, leakage and particle size of these materials to determine whether a relationship exists between these properties. The viscosity of each material was measured and compared with the Student's t test. MTA Angelus Fluid's viscosity was significantly lower than the other two materials tested. Microleakage of root end fillings was assessed in a passive diffusion model. Leakage groups were compared with a one-way ANOVA (p < 0.05). No significant difference was found. Particle size and shape were evaluated with the SEM. MTA Angelus Fluid has a lower viscosity than the other materials tested. There was no significant difference in the sealing ability of the three materials tested and there was no apparent variation in each material's particle size or shape.