canal preparation for rct
DESCRIPTION
cleaning and shapingTRANSCRIPT
Objectives of Canal Preparation
Start with the end in mind
Objectives of root canal preparation
The root canal system must be:• Cleaned of its organic remnants• Shaped to receive a three
dimensional filling of the entire root canal space
Objectives of root canal preparation
The canal is • Cleansed primarily by irrigation• Shaped primarily by
instrumentation
Five Mechanical objectives
•Develop a continuously tapering conical form in the root canal preparation•Make the canal narrower apically, with the narrowest cross-sectional diameter at its terminus•Make the preparation in multiple planes•Never transport the foramen.•Keep the apical foramen as small as possible Herbert Schilder
The real key to obturation is Cleaning and Shaping
Cleansing of the root canal
Objectives• Removal of organic and
inorganic debris• Elimination of bacteria
InstrumentsInstruments differ according to:• Metal• Tip design• Cross sectional geometry• Length of cutting blades• Sizing• Taper
Metals
Nickel titanium Stainless steel
Excellent flexibility Less flexible
Conforms to canal Straightens and curvature transports canal
No deformationPermanent deformation
ISO-Symbols
= K-Reamer
= K-File
= H-File
= Rat Tail File
= Nervbroach
= Paste Filler
METHODS OF DETERMININGWORKING LENGTH
• Radiographic Methods• Digital Tactile Sense• Apical Periodontal Sensitivity• Paper Point Measurement• Electronics
Clinical Technique
Actual WL determination• Radiograph• Apex locator
Clinical Procedure
Apex Locator
Clinical Procedure
Actual WL determinationPreparation should terminate at• Apical constriction• 1 mm short of radiographic
apex
Clinical Procedure
• Estimate working length• Parallel radiograph• Estimated working length is the distance
from the reference point to the radiographic apex
• Apico coronal techniques( standardized ,step-back, balanced force )
• Corono-apical techniques ( step-down , Double flared, crown-down-pressureless)
Root canal preparation
• Standard technique• Step-back technique• Serial shaping technique• Anti-curvature filing• Balance force
preparation• Crown down technique
Instrumentation
• Motion of instrumentation:Filing and Reaming
• Combination with reaming and filing:
1. Turn-and-Pull2. Watch-Winding3. Watch-Winding-and-Pull
• Anti-curvature filing
Step-back technique
Step-back technique
Master Apical File
• Take a radiograph with MAF in place. This confirms:– Length– Placement
RECAPITULATIONRepeated reintroduction and reapplication of instruments
previously used throughout the cleaning and shaping process in
order to create well-designed, smooth, unclogged, evenly tapered
root canal preparations.
Apical PatencyMaintain a pathway
through the apical constriction with a small K-file (#10 or #15)
during cleaning and shaping
Other methods ;
Crown Down Technique
•Coronal third Orifice shapers•Middle third 0.06 taper rotary Profiles•Apical third 0.04 taper hand Profiles
Crown Down Technique
• The coronal portion is prepared before the apical portion
• Reduces effect of canal curvature• Improves tactile awareness during apical
preparation• Allows more effective irrigation• Removes majority of tissue and microbes
before apical third is approached• Reduces change in working length during
apical preparation
Anti-curvature filing
Irrigation
An ideal irrigant:• Is nontoxic • Dissolves vital and necrotic tissue• Is bactericidal• Lubricates the canal
• Sodium Hypochlorite:• Lower concentrations (e.g., 0.5% or1%) dissolve mainly
necrotic tissue
• Chlorhexidine:• A broad-spectrum antimicrobial agent effective against
gram-negative and gram-positive bacteria• A cationic molecular• binds to hydroxyapatite
Iodine Potassium Iodide:• an oxidizing agent by reacting with free sulfhydryl
groups of bacterial enzymes• MTAD• EDTA• Hydrogen peroxide
Cleaning---Irrigation
• Sodium Hypochlorite?• Dissolves organic debris ✔• Has a powerful anti-bacterial action ✔• Lubricates the use of files ✔• Disinfects & cleans where files don’t reach
✔• The tissue-dissolving ability of 5.25-
1%
What irrigant should we use?
Sodium hypochlorite
• Dissolves vital and necrotic tissue
• Is bactericidal• Lubricates the canal
Smear layer
• What is the smear layer ?
• Remove ?
Prolube
• Facilitates placement of file• Entraps debris• Aids in removal of the smear
layer
EDTA and carbamide peroxide in a water soluble base
Good luck