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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
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What are the criteria for cleaning and shaping?
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What are the goals of irrigation?
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What is the function of sodium hypochlorite?
Sodium hypochlorite denatures and damages proteins (like collagen)
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Why do you never want to wedge a needle into the canal and irrigate?
The irrigant would be forced out of the apex
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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
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What is recapitulation?
Checking to see if the master apical file goes to length
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What is the step back method?
Work backward from the apex to get more taper
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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
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Why do we want to start our apical preparation with small files?
Smaller files used to gather initial length and maintain patency
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What is a patency file?
- Maintains patency of the apex
- Removes debris from the apical area
- Pre-curved
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How large are patency files usually?
#10 or #15/20 in big canals
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How far do we insert the patency file?
All the way to the radiographic apex
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Which files are considered the workhorse?
SS Flex-R- Files
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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
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What is the "quarter turn and pull" technique? What follows it?
- A technique used to reach length
- Followed by circumferential up-down filing
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What is the master apical file?
- The largest file brought to length
- At least size 30
- Used for cleaning and shaping
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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
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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
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What type of instruments do we use for coronal flare?
Gates-Glidden drills
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Which technique do we use for the coronal flare?
The crown-down technique
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What are Gates-Glidden drills?
- Used for coronal flares
- Stainless steel and not flexible
- Used at slow speed and high torque
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How much should the canal be opened before using Gates-Glidden Drills?
at least #25
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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
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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
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Which files are used in a step-back technique?
Ordinary .02mm/mm taper files
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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
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What are GT NiTi hand files used for?
- Used for flaring
- Crown down: .10, .08, .06
- Used for checking flare
- Has a reverse thread
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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
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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
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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
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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
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X-Smart Endo Motor Set up features
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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
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When will we not use the NiTi files at all?
Not used with sharp or >30 degree curves
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Why alternate .06 and .04 taper files?
- Limit file contact and engagement
- Less binding
- Less suck-down
- less breakage
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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
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Can rotary NiTi files be reused on patients?
No, one use only
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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
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What is recapitulation?
- Debris removal
- smoothening walls
- blend prep and parts together
- ensure length is maintained
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Canal preparation and features diagram
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What are some common errors during root canal cleaning and shaping?
- Strip perforation
- File separation
- Ledging, transportation, zipping, perforating
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What does the spreader test check for?
- If there is adequate flare
- Adequate cleaning
- room for obturation
- Is it within 2-3mm of apex
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