Card Set Information
Endo lecture 5
What are the three file types?
2. Stainless steel
3. Nicket titanium (what we use today)
What is the taper of a nickel titanium rotary instrument?
For every mm, you increase .02mm
There is a .04 taper and a .06 taper
Which hand and rotary instruments are lathe ground or machined?
Hedstrom, most nickel titanium, and some K-files
How are hand/rotary instruments ground and twisted?
Ground into square, triangular, or rhomboid blanks
Twisted counterclockwise to produce helical cutting edges
Have a pyramidal tip of 75 degrees or -15 after twisting that is rounded and
Which has more twists/mm, reamers or files?
Files have more twists/mm
File and reamer shapes
How far do cutting flutes extend up to the tip of the file?
What is the change in tip sizes?
Tip size increases by .05mm up to size #60
Tip size increase .10mm from #60-140
File diameter increases
.02mm/mm of length
What are the tapers on Nickel titanium instruments?
.02, .04, .06, .08, .10
Between which two file sizes is there the largest increase?
Which files are hand operated?
K-type files and reamers
Which files and reamers are engine driven?
Files and reamers (constant counterclockwise rotary motion
Files and reamers (reciporocates 90-180 degrees each way)
What are some aspects of carbon steel files vs. stainless steel?
What is the torsional limit?
Amount of rotational torque that can be applied to a 'locked' instrument to the point of breakage
Which instruments have higher torsional limits?
Smaller instruments (<20) withstand more rotations than larger
Machined files deform more quickly
Nickel titanium files have increased resistance to fracture compared to stainless steel
How do you avoid separation, unwinding, and roll-up?
Inspect instruments before each use
unwinding results from
Roll-up results from
Instruments separate more easily in a counter-clockwise direction
Nickel titanium rotary instruments
50/50 combination of Nickel and Titanium
Very corrosion resistant
Superelastic, has shape memory
Has two reversible configurations (austenite and martensite)
More resistant to fracture than stainless steel and more
difficult to pre-bend
Usually made by
What are some features of the X-smart endo motor?
Speed and torque control
Able to program settings
What RPM are Gates Glidden files set at?
What RPM are numbered files set at?
What does sterilization do?
Unlike disinfection, sterilization
kills all organisms
They can't eliminate Prions
What are the two types of sterilization?
1. Pressure (steam and chemclave)
2. Dry heat
What are the settings for Steam sterilization?
121 degrees Celcius and 20 psi for 30 minutes
What are the operations for Chemclave?
Causes less rusting of steel instruments than steam
Uses alcohols, ketones, formaldehyde, and water
127 degrees Celcius and 20 psi for 20 minutes
Which dulls cutting edges faster, Pressure or Dry heat?
Pressure dulls cutting edges faster
What are the types of disinfectants?
70% isopropyl alcohol
Quarternary ammonium solutions
Sodium hypochlorite 5.25% to 6%
What are the irrigants used today for canals?
NaOCl- Kills bacteria and
dissolves necrotic tissue
EDTA- Kills bacteria and
Chlorhexidine- Kills bacteria with
no tissue dissolution
Distilled water- only flushing and debris removal
Action of sodium hypochlorite
Sodium hypochlorite 5% at 50 degrees C
Should be left in canals for a
minimum of 10 minutes
High pH (11-12)
Reduces bacterial colonization except
enterococcus and actinomyces
Can dissolve necrotic tissue
Reduces toxic by-products
lentulo spirals or compaction of dry CaOH poweder
What is the smear layer?
1.Fragments of microscopic mineral crystals produced by instrumentation
3. Bacteria and by-products, viruses, fungi, yeasts
Why do we want to remove smear layer?
Source of substrate for bacterial growth
Avenue for leakage
may prevent or delay disinfectant action
may interfere with sealer or gutta percha adhesion
How is the smear layer removed?
Organic and inorganic acids
EDTA, RC Prep, 5-10% Citric acid