Cleaning and Shaping II PDF

Cleaning And Shaping II Dr Nada Ibrahim A SHORT REVISION OF THE TECHNIQUES WORKING LENGTH DETERMINATION ¡ Traditional treatment has held that canal preparation and subsequent obt...

Cleaning And Shaping II Dr Nada Ibrahim A SHORT REVISION OF THE TECHNIQUES WORKING LENGTH DETERMINATION ¡ Traditional treatment has held that canal preparation and subsequent obturation should terminate at the apical constriction, the narrowest diameter of the canal. ¡ This point is believed to coincide with the cementodentinal junction. ¡ The position and anatomy of the CDJ varies considerably from tooth to tooth, from root to root, and from NADA IBRAHIM - CLEANING & SHAPING wall to wall in each canal. 3 THE INSTRUMENTATION AND OBTURATION OF THE ROOT CANALS SHOULD END AT THE APICAL CONSTRICTION FOR THE FOLLOWING REASONS ¡ No apical injury ¡ No injury to the periodontal ligament ¡ Maintenance of accessory lateral canals ¡ No extrusion of the root canal filling materials ¡ No apical transport of infected pulpal tissues ¡ Adequate compaction of the root canal filling against the canal walls ¡ No infected tissue remnants withing the canal.  ¡ Tooth length determination STEP BACK ¡ Selection of initial file ¡ Initial File is inserted into the canal to the full working TECHNIQUE length using a watch winding motion until it becomes loose PHASE 1 ¡ The procedure is repeated until the apical area is prepared (APICAL PREPARATION) at least THREE successive files after IF ¡ MAF – largest file that will reach the full working length 5 NADA IBRAHIM - CLEANING & SHAPING PHASE I – PREPARATION OF APICAL CONSTRICTION ¡ Apical preparation up to 3 files after the initial file, to the FULL WORKING LENGTH ¡ With recapitulation with a smaller file. Your last file in phase 1 is your MASTER FILE NADA IBRAHIM - CLEANING & SHAPING 6 PHASE II – PREPARATION OF THE REST OF THE CANAL ¡ Stepping backwards using larger size files while shortening working length (usually 1 mm) to obtain a flared preparation ¡ With recapitulation and irrigation between each file So , we increase the size, but decrease the length 1 mm each time NADA IBRAHIM - CLEANING & SHAPING 7 NADA IBRAHIM - CLEANING & SHAPING 8  ¡ Straight line-access (flare the wall). ¡ Establish the WL with size #15 and instrument the canal with same size in watchwinding strokes to establish apical patency. ¡ Instrument the canal from #20-40. (each as far as it goes passively). PASSIVE STEP ¡ Insert size #2 G.G without activation to a point where it binds, pull it back 1-1.5 mm then activate the G.G (#4 BACK Gates-Glidden and reamer can be used in large canals) TECHNIQUE ¡ Confirm the WL before canal preparation. ¡ Flare the coronal 2-3 mm further with G.G ¡ Apical preparation with sequentially larger files from the working length. ¡ In curved canals it should be limited to #25-#30. NADA IBRAHIM - CLEANING & SHAPING 9 NADA IBRAHIM - CLEANING & SHAPING 10 NADA IBRAHIM - CLEANING & SHAPING 11  BALANCED ¡ Insertion : clockwise 60 Degrees FORCE ¡ Apical pushing with rotation of 120 degrees counterclockwise TECHNIQUE ¡ Removal by giving 60 degrees rotation clockwise NADA IBRAHIM - CLEANING & SHAPING 12 NADA IBRAHIM - CLEANING & SHAPING 13 CROWN DOWN TECHNIQUE ¡ Enlarge the coronal third of the canal with progressively smaller GG drills or with other rotary instruments ¡ This technique relies more on coronal flaring and then the determination of the working length later in the procedure ¡ This technique consisted of an exploratory action with a small file NADA IBRAHIM - CLEANING & SHAPING 14 CROWN DOWN TECHNIQUE ¡ After preflaring of the canal orifices. This can be done by using hand instruments, Gates- Glidden drills or the nickle-titanium rotary instruments. After that a glide-path is created by using # 10 or 15 file. ¡ The crown down approach begins with larger Gates-Glidden first (size 4 or 5), followed by smaller Gates-Gliddens are worked into the canal with additional 1 mm to complete coronal flaring. ¡ A care should be taken to avoid carrying all the Gates-Glidden drills to same level which may lead to excessive cutting of the dentin. NADA IBRAHIM - CLEANING & SHAPING 15  ¡ Frequent irrigation with sodium hypochlorite and recapitulation with a smaller file (usually No. 10 file) to prevent canal blockage. ¡ After establishing coronal and mid root enlargement, explore the canal and establish the working length with small instruments (# 10 or 15 file) ¡ Introduce larger files to coronal part of the canal and prepare it. Subsequently introduce progressively smaller number files deeper into the canal in sequential order and prepare the apical part of the canal ¡ Final apical preparation is prepared and finished along with frequent irrigation of the canal system. NADA IBRAHIM - CLEANING & SHAPING 16 NADA IBRAHIM - CLEANING & SHAPING 17 ANY QUESTIONS SO FAR?!  19 THE SMEAR LAYER IN ENDODONTICS ¡Whenever dentin is cut using hand or rotary instruments, the mineralized tissues are not shredded or cleaved but shattered to produce considerable quantities of debris ¡The first researchers to describe the smear layer on the surface of instrumented root canals were McComb & Smith in 1975 NADA IBRAHIM - CLEANING & SHAPING  20 THE SMEAR LAYER IN ENDODONTICS ¡The smear layer consists not only of dentin as in the coronal smear layer, but also the remnants of odontoblastic processes , pulp tissue and bacteria ¡Its an organic matter trapped within translocated inorganic dentin ¡The generation of a smear layer is almost inevitable during root canal instrumentation NADA IBRAHIM - CLEANING & SHAPING  ¡ It has unpredictable thickness and volume, because a great portion of it consists of water ¡ It contains bacteria, their by-products and necrotic tissue. Bacteria may survive and multiply and can proliferate into the dentinal tubules SHOULD THE ¡ It may limit optimum penetration of disinfecting agents SMEAR LAYER ¡ It can act as a barrier between filling materials and the BE REMOVED?? canal wall and therefore compromise the formation of a satisfactory seal In Support of Removal ¡ It is a loosely adherent structure and a potential avenue for leakage and bacterial contaminant passage between the root filling and the dentinal walls 21 NADA IBRAHIM - CLEANING & SHAPING  SHOULD THE ¡ Bacteria remaining after canal preparation SMEAR LAYER are sealed into the tubules by the smear BE REMOVED?? layer and subsequent filling materials In Support of Retaining 22 NADA IBRAHIM - CLEANING & SHAPING SHOULD WE REMOVE IT OR NOT ??!!! Shahravan et al 2007 Systemic Review and Meta-Analysis ¡ 54% of comparisons reported no significant difference ¡ 41% reported in favor of removing the smear layer ¡ 5% reported in favor of keeping it They concluded: Smear layer removal improved the fluid tight seal of the root canal system NADA IBRAHIM - CLEANING & SHAPING 23  Methods to Remove the Smear Layer Chemical Removal SUSAN FLOWERS 5.25% Sodium Manager 17% EDTA Hypochlorite Inorganic Tissues Organic tissues Most Effective Final Rinse : 10 mL of 17% EDTA , followed by 10 mL Saline , followed by 10 mL of 5.25% NaOCl PROBLEM SOLVING IN CLEANING AND SHAPING LOSS OF WORKING LENGTH ¡ The problem is often only noted on the master cone radiograph or when the master apical file (MAF) is short of the intended or initial working length ¡ Loss of working length may be secondary to other procedural errors ( eg canal blockages, ledges, perforations, fractured instruments) which occur during the canal enlarging and shaping process and can be identified early in the procedure ¡ The loss of working length is due to the packing of dentin chips in the apical third of the canal SHORTCOMINGS THAT PROMOTE LOSS OF WORKING LENGTH ¡ Failure to irrigate frequently and copiously with a tissue dissolving irrigant ( sodium hypochlorite) ¡ Failure to recapitulate ¡ Failure to radiographically verify the working length during the enlarging process ¡ Malpositioned instrument stops ¡ Failure to record and regularly use stable reference points ¡ Skipping instrument sizes, especially in curved canals ¡ Fracturing an instrument without realizing it has occurred ¡ Aggressive use of instruments in small, tight, and curved canals NADA IBRAHIM - CLEANING & SHAPING 28 HOW TO AVOID THESE ERRORS??! ¡ Attention to detail during instrument application ¡ Generous use of irrigant during enlarging and shaping. NADA IBRAHIM - CLEANING & SHAPING 29  ¡ The clinician should choose a small but stiff instrument ( size 15 K-File) to bore through the obstruction ¡ The file is inserted into the canal and slowly rotated circumferentially to detect a catch( the space WHAT TO DO IF between particles and canal wall) IT HAPPENS? ¡ Once the catch is felt, the file is carefully rotated in a watch-winding motion along with a slight in- and- out motion until the tip of the instrument bypasses the obstruction and negotiates the canals to length ¡ Once the instrument begins to advance further in the canal, a radiograph is taken to verify position of the file NADA IBRAHIM - CLEANING & SHAPING 30  REGAINING YOUR WORKING LENGTH NADA IBRAHIM - CLEANING & SHAPING 31 ¡ To go through the dense blockage with dentinal chips, chelating agents such as RC-Prep, or liquid EDTA may be used to soften the plug to facilitate penetration ¡ If the plug has not been penetrated, the file may be creating a false canal in the dentinal wall. NADA IBRAHIM - CLEANING & SHAPING 32  ¡ Ledges : that can occur anywhere along the length DEVIATIONS of the canal FROM THE CANAL ¡ Zips: the usually occur at the apical extent of the canal ANATOMY ARE ¡ False canals: which occur if the ledge is accentuated with aggressive instrument activity of USUALLY IN THE the instrument tip against the wall until the instrument creates its own exit out of the root FORM OF : ¡ Strip perforations : occur with the lateral cutting of an instrument anywhere along the root wall ( primarily in the danger zones ) NADA IBRAHIM - CLEANING & SHAPING 33 HOW TO AVOID THESE ERRORS? ¡ Developing smooth, clean pathway in the canal before placement of specific files used for enlarging and shaping ¡ Using the instruments only to their desired length for only a few seconds. ¡ Repeated placement of these instruments to length or holding them at length during rotation will result in canal deviations possible breakage, especially if excessive pressure is placed on the instrument by the clinician NADA IBRAHIM - CLEANING & SHAPING 35 CONCLUSION ¡ Endodontists have a wide array of instruments and techniques at its disposal ¡ Even the best of instruments have its limitations in the hand of an inexperienced practitioner ANY QUESTIONS?!