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What are the aims of cleaning and shaping?
- Remove bacteria and debris to create healing environment
- 1. Smooth and continuous taper and flare
- 2. Small apical opening
- 3. Irrigation of the entire canal system
- 4. Facilitate obturation
What are the criteria for cleaning and shaping?
What are the goals of irrigation?
What is the function of sodium hypochlorite?
Sodium hypochlorite denatures and damages proteins (like collagen)
Why do you never want to wedge a needle into the canal and irrigate?
The irrigant would be forced out of the apex
What is the standard taper of most hand files?
- 0.02mm/mm taper
- The width change between Do and D16 is .32mm
- NiTi files often have greater tapers up to .12mm/mm
What is recapitulation?
Checking to see if the master apical file goes to length
What is the step back method?
Work backward from the apex to get more taper
What is the UCLA treatment sequence?
- 1. Apical preparation
- 2. Coronal Flare
- 3. Overall flare
- Step-back with hand files
- Hand NiTi GT (greater taper) files
- Rotary NiTi
- 4. Recapitulation
Why do we want to start our apical preparation with small files?
Smaller files used to gather initial length and maintain patency
What is a patency file?
- Maintains patency of the apex
- Removes debris from the apical area
How large are patency files usually?
#10 or #15/20 in big canals
How far do we insert the patency file?
All the way to the radiographic apex
Which files are considered the workhorse?
SS Flex-R- Files
What is the initial apical file?
- The first file to feel snug at length
- Usually sizes 15-40
- When it's loose, change to the next file
What is the "quarter turn and pull" technique? What follows it?
- A technique used to reach length
- Followed by circumferential up-down filing
What is the master apical file?
- The largest file brought to length
- At least size 30
- Used for cleaning and shaping
What is the anti-curvature technique?
- The file is pressed against the outer wall (the safe side)
- The file is pressed away from the furca
- Prevents strip-perforation
- Maintains natural curvature
- Files are pre-curved
How are the safe sides of canals named?
- The safe outer sides take the names of the canals
- ex: safe side of disto-buccal canal is the disto-buccal side
What type of instruments do we use for coronal flare?
Which technique do we use for the coronal flare?
The crown-down technique
What are Gates-Glidden drills?
- Used for coronal flares
- Stainless steel and not flexible
- Used at slow speed and high torque
How much should the canal be opened before using Gates-Glidden Drills?
at least #25
What are the steps for using a GG drill for coronal flare?
- 1. drop passively into an open canal
- 2. Prep on the safe side: anti-curvature shaping
- 3. Prep on upstroke only, never on downstroke
Which three techniques can be used to get an overall flare?
- 1. Step-back with hand files
- 2. Hand NiTi Greater Taper GT files
- 3. Rotary NiTi
Which files are used in a step-back technique?
Ordinary .02mm/mm taper files
How far should you go on the first step of the step-back technique?
- The first step is 1mm to preserve the apical stop
- Sequential stops are 0.5mm to give .1 taper
- Sequential stops of 1.0mm give .05mm taper
What are GT NiTi hand files used for?
- Used for flaring
- Crown down: .10, .08, .06
- Used for checking flare
- Has a reverse thread
What are rotary NiTi instruments used for?
- Crown-down technique
- Must open canal up first with apical prep and coronal flaring
- Don't bind file by using on-off technique
- 7 seconds maximum per canal
What are the color codings and tip sizes for Black, Green, Blue, and Red bands on NiTi 'Profile ISO" rotary instruments?
- Black- #40
- Green- #35
- Blue- #30
- Red- #25
How can you tell taper on NiTi Profile iso Rotary instruments
- 2 rings and red stop= .04 taper
- 3 rings and green stop= .06 taper
What are some of the features of Rotary NiTi handpieces?
- Very slow 300 rpm for NiTi files
- Slow 800 rpm for GG's
- Torque control and auto reverse functions
- Apex locator option
- Only use after mastering hand instruments
- Good for easy canals only
X-Smart Endo Motor Set up features
How close to the apex do NiTi files go?
- 1mm shorter than MAF in a dead straight canal1mm shorter than MAF for a mid-root curve <30 degrees
- 1mm shorter than MAF for a coronal curve <30 degrees
- 2mm shorer than MAF for apical curve <30 degrees
- Never further or a bigger size than the MAF
When will we not use the NiTi files at all?
Not used with sharp or >30 degree curves
Why alternate .06 and .04 taper files?
- Limit file contact and engagement
- Less binding
- Less suck-down
- less breakage
When do we avoid rotary NiTi?
- Sharp apical, mid-root, or coronal curvatures >30 degrees
- Dividing or merging canals
- Very wide or highly flared canals
Can rotary NiTi files be reused on patients?
No, one use only
Avoiding errors with rotary
- Straight line access
- Avoid difficult anatomy
- Use ss files to bypass any ledges
- Don't engage the entire length of the file
What is recapitulation?
- Debris removal
- smoothening walls
- blend prep and parts together
- ensure length is maintained
Canal preparation and features diagram
What are some common errors during root canal cleaning and shaping?
- Strip perforation
- File separation
- Ledging, transportation, zipping, perforating
What does the spreader test check for?
- If there is adequate flare
- Adequate cleaning
- room for obturation
- Is it within 2-3mm of apex
What would you like to do?
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