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55 Cards in this Set
- Front
- Back
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What must be done to the root canal system in cleaning and shaping?
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- cleaned of its organic remnants
- shaped to receive a 3D filling of the entire root canal space |
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What is the canal primarily cleansed by?
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Irrigation
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What is the canal primarily shaped by?
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Instrumentation
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What are the objectives of cleansing of the root canal?
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- removal of organic debris
- elimination of baceria |
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What methods is canal disinfection achieved by?
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- irrigation
- mechanical instrumentation - intra-canal medicaments |
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What are the properties of an ideal irrigant?
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- non-toxic
- dissolves vital and necrotic tissue - is bactericidal - lubricates the canal - removes the smear layer |
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What does sodium hypochlorite do?
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- dissolves vital and necrotic tissue
- is bactericidal - lubricates the canal |
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What 3 things does RC-Prep do?
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1. facilitates placement of file
2. entraps debris 3. aids in removal of smear layer |
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What kind of agent is EDTA? What does it do?
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chelating agent; effectively removes smearlayer
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What is the objective of shaping of the root canal?
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Smooth tapered preparation
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What stages are needed for getting a radiograph?
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Preop (2 views)
IWL (1 or 2) FWL MAF MGP Obturation Final |
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What is the definition of recapitulation?
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reintroduction of small files in C&S to keep the apical area clean
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What is apical patency?
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where the apical foramen remains free of debris by re-introduction of small files (10, 15) through apical foramen (0.5mm)
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What is taper?
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increase in diameter per unit length
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What factors do instruments differ according to?
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metal, taper, tip design, cross-sectional geometry, length of cutting blades, sizing
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What 3 properties does Nickel Titanium have?
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1. excellent flexibility
2. conforms to canal curvature 3. plastic deformation |
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What 3 properties does Stainless Steel have?
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- less
- straightens and transports canal - permanent deformation |
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What is the length of the cutting blade?
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traditionally 21, 25, 31mm
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What is the active blade length?
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16mm
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What does the ISO size number refer to?
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Tip of diameter in tenths of mm
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What size does the tip diameter increase by?
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0.05mm from sizes 10-60, then by 0.1mm
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What is the % increase in diameter from #10 to #15 file?
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50%
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What is the difference between #55 and #60?
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9%
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In the crown down technique, the ____ portion is prepared before the _____
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coronal, apical
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The crown down technique follows what principle?
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medical - cleansing before probing a wound
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What are the advantages of the crown down technique?
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- eliminates constrictions in coronal region
- reduces effect of canal curvature - improves tactile awareness during apical prep - allows more effective irrigation - removes majority of tissue and microbes before apical third is approached - reduces change in working length during apical prep |
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How do you calculate the coronal third measurement?
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IWL - 8mm
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How do you calculate the middle third measurement?
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IWL - 4mm
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What is the apical third measurement?
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FWL
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What instruments should be used in the coronal third?
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H-file, K-file, GG (size 2 and 35, 40 & 3 at 45, 50)
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What instruments should be used in the middle third?
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H-file, K-file, no GG
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What instruments should be used in the apical third?
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K-file, no H-file
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Where should the FWL preparation terminate at?
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apical constriction; 1mm short of radiographic apex
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Why 1mm from the apical foramen?
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Chugal et al (2003), every 1mm short has 14% less success
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What is the Master Apical File?
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MAF -- largest apical file that extends to working length
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For large canals, what is the minimum MAF?
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#40-50
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For small canals, what is the minimum MAF?
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#40
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What should be done to stop debris blockage during apical prep?
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Copious irrigation with NaOCl
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What should be done once the MAF has been found?
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Take a radiograph with MAF in place
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What does the radiograph of the MAF confirm?
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Length, placement, 1mm from foramen
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Why 3 sizes up for MAF?
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- biofilm on canal wall
- microbes in dentinal tubules (Svensater and Bergenholtz, 2004) |
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Why might more than 1mm of distance from foramen be needed?
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- root resorption
- open apex - lateral foramen exit |
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Should files be precurved in C&S?
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Yes - mostly in curved canals
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What pressure should be used apically in C&S?
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minimal
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What file should you start with in C&S, when should you move onto a bigger size?
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Small; move on when it gets loose
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Should you force the file?
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no
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How should you be sure that you are on the correct WL?
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recheck position of rubber stopper
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When should you irrigate?
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between each instrument - use lots!
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What movement should the irrigation needle tip be able to achieve? Why?
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Free in canal - to stop pushing material to apical zone
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What quality should the walls have at the end of instrumentation?
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Smooth
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What kind of transition should there be at the end of instrumentation?
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Smooth from one zone to another - should be no step!
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If there is a step, what should be done?
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middle and coronal zone final sizes should be modified
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Be careful not to overuse the____. Why?
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MAF. should have some retention at apical zone to create a good apical seat/stop
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Ensure to ____ each file before introducing it into the canal
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checking
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What should be done if you see any deformities or untwisted blades?
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Throw them away; replace with new ones
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