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At least 55 records · Page 3Linked to original sources
PubMed2003

An assessment of predictive forecasting of Juniperus ashei pollen movement in the Southern Great Plains, USA.

Juniperus ashei pollen, a significant aeroallergen, has been recorded during December and January in Tulsa, Oklahoma, over the past 20 years. The nearest upwind source for this pollen is populations growing in southern Oklahoma and central Texas, at distances of 200 km and 600 km respectively. Long-distance dispersal of J. ashei pollen into the Tulsa area shows a strong correlation with the trajectories of wind blowing across southern populations before traveling north towards eastern Oklahoma. The strong tie between climatic conditions and the occurrence of this aeroallergen within the Tulsa, Oklahoma, atmosphere provided a unique opportunity to forecast the dispersal, entrainment, and downwind deposition of this significant aeroallergen. Forecasts of long-distance J. ashei pollen dispersal began during the winter of 1998/1999. Each forecast uses defined climatic parameters to signal pollination at each source site. Coupled to these estimates of pollen release, forecast weather conditions and modeled wind trajectories are used to determine the threat of dispersal to downwind communities. The accuracy of these forecasts was determined by comparing the forecast "threat" to aerobiological records for the same period collected in the "Tulsa region". Analysis of the two seasons revealed only a single occurrence of "high" or "very high" pollen concentrations in Tulsa not directly linked to "moderate" or "severe" forecast threats from the southern source areas.

Forecasting↗
PubMed2001

Coronal leakage following three obturation techniques.

AIM: To compare coronal bacterial and India ink leakage in three different obturation techniques with the smear layer having been removed. METHODOLOGY: Seventy extracted single-rooted teeth were instrumented to an apical preparation size 7 Profile Series 29 (Tulsa Dental Products, Tulsa, OK, USA). The smear layer was removed and 20 teeth were randomly obturated with lateral compaction, 20 teeth with vertical compaction, and 20 teeth with Thermafil (Tulsa Dental Products, Tulsa OK, USA). Ten teeth were used for positive (five teeth) and negative (five teeth) controls. Teeth were stored for 90 days in 100% humidity, then subjected coronally to Proteus vulgaris for 21 days to assess bacterial leakage. Following bacterial challenge, India ink was placed coronally for a further 21 days, then scored according to depth of dye leakage. RESULTS: Vertical compaction leaked significantly less than lateral compaction during bacterial challenge. However, when dye was used there were no significant differences. CONCLUSIONS: Bacterial leakage and dye leakage demonstrated considerable variability. The use of a dye following bacterial testing may highlight the failure of experimental devices and vertical root fractures, thus avoiding false positive results found with bacterial testing alone.

Carbon↗
PubMed2006

An ex vivo comparison of three different gutta-percha cones when compacted at different temperatures: rheological considerations in relation to the filling of lateral canals.

AIM: To compare ex vivo the penetration of three brands of gutta-percha cones, compacted under a constant force and heated to different temperatures, into artificial lateral canals. METHODOLOGY: Resin blocks with simulated main canals, each having two lateral canals (C at 6.5 and A at 13 mm from the surface of the resin block), were selected. A gutta-percha cone, either Mynol MF, Hygenic MF or GT Tulsa 0.04 was compacted into each main canal for 5 s using a wire rod with a diameter of 0.7 mm soldered to the bottom of a metal cylinder, with a force of 2.7 kg at controlled temperatures of 37, 42, 47, 52, 60 degrees C. The penetration of each brand of gutta-percha into 60 lateral canals (10 at each temperature) was measured using a stereomicroscope. Statistical analysis was performed using the ANOVA, the Scheffè test and the t-test. RESULTS: None of the three brands of cones entered up to 0.1 mm within either lateral canal until a temperature of 47 degrees C was reached; at that temperature only Mynol cones (P < or = 0.05) penetrated in four of 10 A-level canals (mean 0.13 +/- 0.19 mm) and in all 10 C-level canals (mean 0.43 +/- 0.12 mm). The A-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.76 +/- 0.34 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.31 +/- 0.12 mm) and Hygenic cones (mean 0.11 +/- 0.08 mm). At 60 degrees C the Mynol cones (mean 1.93 +/- 0.34 mm) penetrated significantly more (P < or = 0.05) than the Tulsa cones (mean 0.86 +/- 0.22 mm) and Hygenic cones (mean 0.67 +/- 0.19 mm). The C-level lateral canals were penetrated at 52 degrees C by Mynol cones (mean 0.91 +/- 0.29 mm) to a significantly greater distance (P < or = 0.05) than Tulsa cones (mean 0.47 +/- 0.16 mm) and Hygenic cones (mean 0.46 +/- 0.15 mm), whilst no significant difference was found at 60 degrees C. CONCLUSIONS: When heated and compacted, the three gutta-percha cones penetrated the lateral canals to different degrees. They penetrated more than 0.43 mm into the lateral canals only at temperatures higher than 47 degrees C.

Dental Pulp Cavity↗
PubMed1994

Microleakage comparison of thermafil versus vertical condensation using two different sealers.

The effect of two different sealers on the quality of the apical seal in roots obturated with Thermafil obturators (Tulsa Dental Products, Tulsa, Okla.) and vertical condensation was tested. Fifty extracted human maxillary anterior teeth were treated with the use of a step-back technique. Teeth were placed into five groups of 10 teeth each. One group served as the positive control. The root canals were obturated using either Thermaseal (Tulsa Dental Products) or Kerr (Kerr Manufacturing Co., Romulus, Mich.) sealer, and Thermafil or vertical condensation. All roots were placed in 1% methylene blue dye for 2 weeks. The roots were cleared, and the degree of linear dye penetration was measured using a Unitron light microscope with a Microcode II digital readout (Boeckeler Instruments, Tucson, Ariz.). The study showed that under in vitro conditions, the Thermafil technique was equivalent in linear leakage to vertical condensation. There were no statistical differences in the mean apical dye penetration between the two sealers or the two obturation techniques.

Analysis of Variance↗
PubMed1999

Corrosion in stainless-steel and nickel-titanium files.

This study evaluated and compared the corrosion susceptibility of stainless-steel and nickel-titanium (NiTi) endodontic files immersed in sodium hypochlorite. For each of the stainless-steel files (Kerr K-Flex, Caulk Flex-O, and Union Broach Flex-R) plus the NiTi files (Union Broach NiTi and Tulsa NiTi), the cutting flutes of 24 ISO size 20 files were immersed into 5.25% sodium hypochlorite. Their open circuit potential (OCP) was recorded for 1 h on a strip chart with high impedance. The strip chart recording for each file was classified into a stability score: (i) stable, (ii) unstable, or (iii) erratic. The OCP was measured by a potentiostat and a standard calomel electrode reference. The OCP classification of unstable and erratic for the files evaluated were as follows: K-Flex (16%), Flex-R (12%), Flex-O (75%), Union Broach NiTi (62%), and Tulsa NiTi (0%). After OCP testing, each of the 120 files was inspected by light microscopy at x 25. The frequencies of visually observed corrosion were detected as follows: K-Flex (2/24), Flex-R (1/24), Flex-O (6/24), Union Broach NiTi (2/24), and Tulsa NiTi (0/24). There was a significant difference in corrosion frequency between brands when evaluated by OCP and light microscopy; however, there was no significant difference between stainless steel and NiTi.

Analysis of Variance↗
PubMed2002

Grass species and endophyte effects on survival and development of fall armyworm (Lepidoptera: Noctuidae).

Grass selections including 10 zoysiagrasses, 18 paspalums, 34 Bermuda grasses, tall fescue, creeping red fescue, and perennial ryegrasses with and without endophyte were evaluated for potential resistance to fall armyworm, Spodoptera frugiperda (J. E. Smith), larvae. Laboratory evaluations assessed the degree of antibiosis among >70 grass lines to first-instar fall armvworms. When all parameters measured were considered, the trend in resistance to fall armyworm among endophyte-infected (E+) and endophyte-free (E-) cool season grasses from greatest to least was: 'Dawson' E+ > APR 1234 > 'Dawson' E- > 'Rosalin' E+ > Lp 5425, 'Rosalin' E-, ATF 480 > 'Tulsa' or: E+ slender creeping red fescue > E+ turf- type perennial ryegrass > E- slender creeping red fescue > E+ forage-type perennial ryegrass > E- forage-type perennial ryegrasses, and E+ tall fescue > E- turf-type tall fescue. Among warm season grasses larval weight gain was reduced on all zoysiagrasses. Larval weight gain also was lower on the Bermuda grasses 'Tifsport', 'Tifgreen', 97-4, 97-14, 97-22, 97-28, 97-39, 97-40,97-54, 98-15, 98-30, and 98-45 than when larvae were fed 'Tulsa' tall fescue or the diet control. Only APR1234 and 'Dawson' creeping red fescue reduced larval survival to the same extent that was observed for zoysiagrasses. Survival on Bermuda grasses was least on 97-8. Seashore paspalums were only rarely less susceptible to fall armyworm than tall fescue, although pupal weights were consistently lower on 'Temple 1' and 'Sea Isle 1' paspalums than that on 'Tulsa' tall fescue. Genetic resistance to key grass pests can reduce insecticide use and simplify management of these cultivars.

Animals↗
PubMed2005

The constitution of mineral trioxide aggregate.

OBJECTIVES: The aim of this study was to determine the constitution of a commercially available root-end filling material, mineral trioxide aggregate, (MTA) (ProRoot MTA, Tulsa Dental, Tulsa, OK, USA). The surface morphology of the material with various treatment conditions was also evaluated. METHODS: The constitution of two commercial versions of MTA was determined before and after mixing with water. The unset material was analysed using Energy Dispersive Analysis by X-ray (EDAX) in a scanning electron microscope (SEM) and X-ray diffraction (XRD). The first technique identified the constituent elements while XRD analysis identified the compounds or phases present. The set material was evaluated using EDAX. The surface morphology of the material stored under various conditions (100% humidity, immersion in water, or immersion in phosphate solution) was evaluated using SEM. RESULTS: The EDAX showed the white MTA to be composed primarily of calcium, silicon, bismuth and oxygen, with the gray MTA also having small peaks for iron and aluminum. The XRD analysis showed gray MTA to be composed primarily of tricalcium silicate and dicalcium silicate. The surface morphology of the materials differed under the various conditions, particularly following immersion in phosphate solution with crystal formation. SIGNIFICANCE: The commercial versions of MTA were shown to have broadly similar constitution to ordinary Portland cement except for the addition of bismuth compounds. The white MTA did not contain iron.

Aluminum↗
PubMed2006

The effect of exposure to irrigant solutions on apical dentin biofilms in vitro.

This study assessed the effectiveness of different concentrations of sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) (Vista Dental Products, Racine, WI), and BioPure MTAD (Dentsply Endodontics-Tulsa Dental, Tulsa, OK). Intracanal contents were collected from 10 patients diagnosed with chronic apical periodontitis. The samples were cultured on hemisections of root apices to generate a polymicrobial biofilm. Each biofilm was separately immersed in 6% NaOCl, 3% NaOCl, 1% NaOCl, 2% CHX, 1% NaOCl followed by BioPure MTAD, and sterile phosphate buffered solution (PBS). SEM analysis showed 6% NaOCl and 3% NaOCl were capable of disrupting and removing the biofilm; 1% NaOCl and 1% NaOCl followed by MTAD were capable of disrupting the biofilm, but not eliminating bacteria; 2% CHX was not capable of disrupting the biofilm. Viable bacteria could not be cultured from specimens exposed to 6% NaOCl, 2 % CHX, or 1% NaOCl followed by BioPure MTAD. These results indicate that 6% NaOCl was the only irrigant capable of both rendering bacteria nonviable and physically removing the biofilm.

Biofilms↗
PubMed2004

Cyclic fatigue testing of ProTaper NiTi rotary instruments after clinical use.

PURPOSE: The purpose of this study was to evaluate the cyclic fatigue of ProTaper nickel-titanium (NiTi) rotary instruments (Tulsa Dental, Tulsa, Okla) after multiple clinical uses. STUDY DESIGN: Two hundred twenty-five ProTaper instruments were divided into 3 groups: A = 75 used as controls, B = 75 used in 2 molars (6-8 canals), and C = 75 used in 4 molars (12-16 canals). The number of rotations to breakage and the fractured tip length were recorded for each file and the mean was calculated by ANOVA. RESULTS: No S1-2 or F1-2-3 instrument separated during intracanal use, even if they were reused for a number of cases (x 4 molar cases). CONCLUSION: It is clear that prolonged reuse of NiTi rotary instruments strongly affects instruments' fatigue, but our data suggest the hypothesis that other factors (primarily errors and misuse) may be more accountable for intracanal instrument separation. Further studies could assess the cyclic fatigue of each instrument at different levels of the shaft by altering the radius of curvature.

Analysis of Variance↗