Department of Endodontology

Temple University

 

 

 

 

 

December03

 

December01

 

 

November 05

November 04

November03

November02

November01

March01

December00

October05

October04

October03

October 02

October01

February01

November00

September05

September04

September03

September02

September01

January01

October00

 

 

 

Week of December 7, 2005

 

 

 

 

Title: Comparison of the cutting efficiency of two ultrasonic units utilizing two different tips at two different power settings

 

Author: Paz et al

 

Journal: JOE Vol 31, Nov 2005 p.824-26

 

Reviewer: Alex Wang, DDS

 

Purpose:

 

1. To set up a testing device to measure and compare ultrasonic units and tips

2. To use this device to investigate the in vitro dentin removal by two ultrasonic units

3. To test the two units with two different diamond coated tips

4. To test both units at maximum (10) and medium (5) power settings

 

Materials and Methods:

 

·        10 extracted mand molars were mounted in epoxy resin blocks

·        A force of 60g was applied to the ultrasonic tip by a vertically moving counter-weighted balance

·        The handpiece was positioned above the pan balance in a fixed device

·        The ultrasonic tip is oriented to contact the teeth at 90 degree angle

·        The P5 booster (Satelec) and the Spartan (Obtura-Spartan) ultrasonic units were used

·        The ET-20D (Satelec) and the CPR-2D (Obtura-Spartan) ultrasonic tips were used

·        Maximum and medium power settings were studied

·        The weight loss of dentin cut from the teeth was recorded after each 60s cycle as an indication of cutting efficiency

 

Results & Conclusion:

 

·        The type of ultrasonic unit, the power setting, and the tip all had an effect on cutting efficiency

·        The maximum power setting was more effective at dentin removal than medium power

·        The P5 ultrasonic unit was more effective at dentin removal than Spartan unit at both power settings

·        The ET-20D (Satelec) tip was more effective at dentin removal than the CPR-2D (Spartan) tip on both power settings

 

 

 

 

 

 

Title: Erbium:YAG laser versus ultrasonic in preparation of root-end cavities

 

Author: Zoran, K., et al.

 

Journal: JOE, Vol. 31, No. 11 (p821-3), Nov. 2005.

 

Reviewer: Brian S. Jeon, DMD

 

Purpose: To compare the sealing effectiveness of the Er:YAG laser to the sealing effectiveness of an ultrasonic device in the preparation of retrograde cavities using different retrograde filling materials. 

 

Materials and Methods:

 

1)      60 fully developed, single rooted, extracted teeth were instrumented to MAF size #40 at the working length (WL) and obturated with gutta-percha and AH Plus sealer.

2)      3 mm root-end resection was made, and the resected roots were randomly assigned to two groups of 30 teeth each: ultrasonic group and laser group.

3)      The root-end cavities, 3 mm in depth and 1.5 mm in diameter, were prepared for both groups, and they were filled with MTA, Super-EBA, or IRM.

4)      Sealing ability of each sample was measured using a fluid transport model described by Wu et al.

 

Results:

 

  • Samples prepared using laser technique showed less micro-leakage regardless of the root-end filling materials used.
  • MTA filling displayed the best sealing ability both in laser and ultrasonic groups, although these results were statistically significant only in the laser group.

 

Discussion: According to this study, the Er:YAG laser could be used for retrograde cavity preparation, although some clinical limits of this laser still have to be overcome, such as size of the handpiece and diameter of fiber.  This study was performed on extracted human teeth, which simplified the root-end preparation procedure.  

 

 

 

 

Title:  An objective evaluation comparing the physical properties of  two brands of stainless steel endodontic hand files

 

Author:  Dearing G., Kazemi R., and Stevens R.

 

Journal:   JOE, November 2005, Volume 31, Number 11, Pages 827-830

 

Reviewer: Bryan Stein, DMD

 

Purpose:  To compare two brands of files (Brasseler vs. Dentsply) for potential breakage by examining their physical properties

 

Materials and Methods:

           

  • 20 files of each brand and size 10-50 (360 total instruments)

 

1) Brasseler-K-type file (F-style)

                  2) Dentsply-Maillefer (Flex-o-file)

 

Measured:

 

  • Resistance to fracture by twisting:

1)      torque at failure,

2)      angular deflection at failure

 

  • Flexibility:  force necessary to bend the file 45 degrees, 3mm from cutting tip
  • Dimensional Uniformity: analyzed diameter consistency 3mm from tip (D3)

 

Results:

 

  • Significant differences between the two brands for resistance to fracture by twisting.  Brasseler files, sizes 10, 15, 40, 45, 50 had lower torque values at failure than the corresponding Dentsply files.  A significant amount of these files did not comply with ADA specification for minimum torque values at failure.  All Dentsply instruments were in compliance. 
  • All files in both groups were in compliance with ADA specification for minimum angular deflection at failure, however all Dentsply instruments had greater degrees of rotation at failure.
  • All files in both groups were in compliance with ADA specification for maximum allowable torque required to bend the file to angle of 45 degrees.  However, Brasseler files, sizes 10, 15, 25, 40, 45, 50 were significantly more flexible than corresponding Dentsply files.
  • Brasseler files had smaller diameters (\more flexible) with greater variations at D3 compared to Dentsply files.  Some of the Brasseler files had greater dimensional variability than allowed by ADA specifications.

 

Conclusions:  Results for torque and angular deflection values at failure suggest the Brasseler files may be at higher risk for separation in the root canal compared to Dentsply files.

 

 

 

 

 

Title: Chelation in root canal therapy reconsidered

 

Author: Zehnder et al.

 

Journal: JOE Vol. 31 No. 11  Nov 2005

 

Reviewer: Brian Chang, DDS

 

Purpose: To assess the interactions of various calcium chelators with sodium hypochlorite (NaOCl)

 

Materials and Methods:

 

  • 17% EDTA, 10% CA (citric acid),  9% STP (sodium triphosphate), 15% ATMA (amino tris methylenephosphonic acid), and HEBP (7% 1-hydroxyethylidene-1, 1-bisphononate) were the calcium sequestrants tested
  • The experiment was three-fold
  • 1. Testing complexing agents and their impact on available chlorine in NaOCl solutions.
    • Aqueous mixtures were prepared at different ratios with chelators and NaOCl.
    • Available chlorine contents in these mixtures were measured and pH values were recorded
  • 2. Calcium chelation and smear layer removal from instrumented root canals.
    • 60 single rooted teeth were used in this experiment, divided into 10 groups
    • Canals were instrumented using Gates Glidden and ProFile instruments to a #45/.04 size to WL
    • 1% NaOCl was used for irrigation during instrumentation, then copiously rinsed with deionized water
    • Teeth were then either irrigated with 5ml of complexing agent/water, or complexing agent/NaOCl
    • The calcium sequestrent solutions were mixed with either water or 1% NaOCl to assess the impact of  NaOCl on these chelators
    • Eulates were saved and analyzed for Calcium content with atomic absorption spectrophotometry.
    • Teeth were then dried and longitudinally fractured and SEM was used to analyze the coronal, middle, and apical thirds for the presence or absence of smear layer by inspecting for visible dentinal tubules
  • 3. Impact of complexing agents on NaOCls antibacterial effectiveness
    • E. faecalis was the test organism used

 

Results:

 

  • 1. Available Chlorine in NaOCl solutions:
    • STP solution did not interact with NaOCl
    • HEBP solution caused some reduction in available chlorine and was dose dependent over time
    • EDTA and ATMA solutions caused an almost complete and immediate loss of available chlorine upon mixing
    • CA  caused the most dramatic loss of available Chlorine, complete loss in less than 1 minute
  • 2. Calcium Chelation and Smear Layer removal
    • NaOCl and STP had no calcium binding efficacy
    • The strength of chelation capacity was as follows: HEBP<EDTA<CA
    • The presence of  NaOCl had no impact on the ability of calcium chelating complexes
  • 3. Impact of complexing agents on NaOCls antibacterial effectiveness
    • Mixing EDTA with NaOCl abolished sodium hypochlorite’s antibacterial effectiveness
    • HEBP did not interfere much with NaOCl’s antibacterial efficacy

 

Discussion:

 

            Antibacterial efficacy and tissue dissolution potential of NaOCl is a function of its free available chlorine in solution. EDTA and CA tend to inactivate the NaOCl by eliminating the free chlorine in solution. Therefore, copious amounts of NaOCl irrigation are required to completely flush out these chelators. Since HEBP did not interfere with NaOCl’s free chlorine content, it may be a viable alternative as an irrigant to mix chairside with NaOCl.

 

 

 

 

To Top

Temple University School of Dentistry. All contents copyright (C) 1996. All rights reserved.
Created: September 20, 2000 Revised: URL:

 

Roy H. Stevens, DDS, MS; Wanda Gordon, D.M.D. - Comments to author:

wgordon@dental.temple.edu

Questions or problems regarding this page? Please mail:

webmaster@dental.temple.edu