The shaping and cleaning using rotary files.pdf
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Innovation in NiTi Endodontics files Presented by Dr. Fahda Algahtani Cleaning and shaping Course objective To understand the metallurgy of NiTi. To classify different NiTi files according to their generation. To identify new technology for manufacturing NiTi files Course outline Histor...
Innovation in NiTi Endodontics files Presented by Dr. Fahda Algahtani Cleaning and shaping Course objective To understand the metallurgy of NiTi. To classify different NiTi files according to their generation. To identify new technology for manufacturing NiTi files Course outline History of rotary files development. Properties of nickel titanium files. Advantage and disadvantage of NiTi. Rotary files design and main types. Rotary files instruction of use. The main mode of failure in rotary files and prevention. Generation of rotary files and implications. Case selection and choosing rotary files for your practice. Introduction History of development NiTi metallurgy and properties. Less time Less effort Efficient & productive Disadvantages of stainless steel files: Stiffness becomes an obstacle with larger sizes, especially in curved canals where many irreversible iatrogenic mishaps are expected, such as ledging, transportation, or zipping. When to use stainless steel files: The stiffness of stainless steel alloy is desirable in small sizes such as six, eight, ten, and 15 when the clinician wants to bypass the small constricted root canals to reach working length at the beginning of the therapy. The introduction of NiTi files Walia introduced (NiTi) alloy to endodontics and found that the new file metallurgy resulted in the production of significantly more flexible files that were more resistance to fracture compared to traditional K type files. NiTi alloy (nickel and titanium) metallurgy Room temperature courtesy CC Superelasticity Thompson S et al, 2000 Baumann MA et al, 2014 Shape memory Kauffman GB etal, 1996 Algahtani FA, 2018 The properties of NiTi files Superelasticity Shape memory controlled memory The properties of NiTi files 1-Superelasticity occurs within a certain temperature range where the material can be challenged or withstand applied stresses without being permanently deformed after the stress is relieved. 2- Shape memory is a term used to describe the ability of a material to deform at a certain temperature and to recover back to its original shape when heated. Therefore, this property is closely related to temperature changes 3-Controled memory is new manufacturer term used to describe the additional heat treatment in traditional NiTi. The NiTi is able to be bend at room to body temperature and maintain the shape of curvature. Properties into clinical meaning High flexibility ➔Can be used to shape curved. ➔Can be used in rotary handpiece High flexibility ➔Cant be use to bypass a ledge or open calcified canal. ➔Need smooth glide path Properties into clinical meaning Patent canal Zipped Apex Transportation FA, 2020 Superelasticity ➔ Can be used to shape curved canals. Superelasticity ➔ Doesn’t show signs of deformation ➔ Don’t keep too long at the apex. (zipping or perforation) Disadvantages of traditional NiTi Expensive The traditional NiTi can not be curved before insertion which cause difficulty in insertion in some clinical situation. The traditional NiTi resist deformation, therefore can transport or zip the canal if left in position for long time. Lack stiffness therefore is not used to bypass ledges or calcification. Doesn’t show deformation before fracture. Cyclic fatigue resistance is low Disadvantages of heat treated NiTi Expensive Lack stiffness therefore it is not used to bypass ledges or calcification. Doesn’t show deformation before fracture. However, cyclic fatigue failure resistance significantly increased. Niti files design The design: (machined surface) Pitch is the distance between two leading point (number of spirals). Constant pitch can cause perforation (screwing effect). Therefore, the pitch is variable along the file. Pitch Handle: tip size Measuring lines Working side tip The tip is non-cutting tip to avoid perforation and aid in file centering ability. Except in retreatment files, the tip is cutting to remove GP so be carful with retreatment file! Helix angle: The helical angle is the angle that the cutting edge makes with the long axis of the file. If Constant ➔ screw effect. Rake angle: The rake angle is the angle formed by the cutting edge and a cross section taken perpendicular to the long axis of the instrument. Increased➔ active cutting , decreased ➔ scrapping. Radial Land: located between two cutting edge. ➔minimize the depth of the cut (aid in centering ability ) and reduce the chance of screwing in and perforation. Flute: wider flutes means wider area available for dentinal debris and less transportation. Rotary file taper Taper: types are constant: 02, 04, 06 ,or variable: (different taper in different areas). The smaller the taper the more conservative and flexible the instrument. O4 taper is more flexible than 06 Rotary file taper 2% 4% 6% 2% 5% 7% Constant taper FA, 2020 Variable taper FA, 2020 Flexibility: ++/-- (inverse relationship) Torsional failure resistance: ++/++ (Positive relationship) Courtesy Dentsply NiTi files using guide The basic concept of use Complete your access cavity first! Find all the canals and remove all chamber calcifications. Then take the working length with size 10 (larger files can be used in larger canals such as incisors, canine, palatal and distal canals in molar. The basic concept of use You can use the orifice opener/modifier to open the coronal 2/3rd of root. 8% Short Large taper Orifice opener design FA, 2020 The basic concept of use Establish your glide path. The glide path is a smooth radicular tunnel from canal orifice to physiologic terminus (foramina constriction). Its minimal size should be a “super loose No. 10” Pre-curve the tip of the file and work the file down the canal using a ‘watch-wind’ motion until working length. Proglider Make sure canal is free and clear of significant debris and blockage, which could lead to iatrogenic events. Path-file The basic concept of use The first file should be K-file that shape the canal to “super loose No. 10 K file” Pre-curve the tip of the K file. Rotary glide-path are present with 02 taper or variable taper to help shape the canal before using rotary files of bigger sizes. Pathfiles courtesy Dentsply Virgin canal Size 10 K file Size 15 K file Size 20 K file The basic concept of use Then follow manufacturer instruction. Use the orifice opener first the follow through the rest of the files. ProTaper Universal ProtTper Gold K3 Use the files in the sequence that is recommended. Be aware of power setting: (Speed in RPM & Torque in gcm) also number of reuse. When to stop? 1. Follow manufacturer instruction. 2.Different opinions Alternatively Apical Stop Apical Seat Open apex When irrigation needle is able to reach Double check the presence apical 2mm from you working length. seat with master apical K-file at WL. The presence of apical seat provide Dentin debris is visible at the confidence that the apex was shaped last 3mm of tip of finishing file circumferentially. The basic concept of use The basic concept of use NiTi files mode of failure The fracture mode of rotary files: Torsional failure Cyclic fatigue failure Prevention is better than cure Definition & prevention of torsional failure Torsional fracture: happens when the apical part of the file binds inside the canal while the coronal half continues to rotate until there is complete separation of the file into two segments. Prevention through: 1-Straight line access cavity. All the canals are accessible. 2-Establish glide path to the working length before using any rotary file. 3-Use the speed and torque that is recommended by the manufacturer. Continue the prevention of torsional failure 4-Frequent irrigation with NaOCL to remove canal debris. 5-Clean the flutes of the file regularly and inspect the file flutes. 6-Crown down technique using the orifice opener. 7-Using the files in the right sequence as recommended by the manufacturer. 8- Use gentle picking motion and don’t force the file inside the canal. Definition and prevention of cyclic fatigue failure Cyclic fatigue failure: the instrument fails during free rotation inside a curvature due to alternating rapid cycles of tension and compression at the point of maximum curvature. Prevention: unpredictable and mainly material dependent Risk factors: 1-acute radius 2- increased angle of curvature. 3-Number of reuse. 4-High taper (06) and large files (30 and above) in curved canal. Manal Alkadi, KSU. Increasing the angle of curvature >30. Decreasing the radius of curvature. Larger file diameter increase fracture risk. RPM has no effect. Nouf Alkhunaini, PNU. NiTi files generations Rotary files generations The generations Many file sizes- fixed taper- passive cutting 1st generation less number of files - 2nd 5th Off-center rotation variable taper-active generation generation cutting Thermomechanical 3rd 4th Reciprocation motion. treatment generation generation Single file per tooth First generation, 1994. Triple U-shape cross-section. Negative rake angle and wide radial land. Scrapping action not active Orifice shaper cutting. Courtesy dentsply Mechanical objectives Continuously tapering funnel. The narrowest diameter is in the region of the apical foramen and the widest diameter is at the coronal aspect. Herbert Schilder, 1967 Well shaped & 3D RC filling cleaned Second generation Convex triangle cross-section active cutting. One orifice opener, 2 shaping file and 3 finishing files The flexibility of the file decreases after F1, not preferred in curved Speed: 300 RPM /Torque: 150-306 GCM canals. Overall 2.6% of cases. Overall.39 55% in severely curved canal. K3>PU>PF (insignificant) F3 (largest diameter). Larger taper 06. Number of reuse. Fracture at the apical area. Second generation, end of 90s. Surface treatment, design of the instrument, improving in metallurgy and manufacturing process were not significant in improving the mechanical properties of NiTi except for heat treatment. Gutmann & Gao, 2011 Third generation, end of 90s. The same design as ProTaper Universal with heat treatment. Flexible and higher resistant to fracture. Reduce the risk of transportation and perforation. Third generation. Profile vortex Significant improvement to cyclic fatigue resistance Significant improvement in the centering ability Properties of 3rd generation files Room temperature Improved resistance to cyclic fatigue and flexibility. Significant improvement in centering ability. Reduced torsional resistance and microhardness. Controlled memory Fourth generation. Reciprocation motion: repetitive back- and-forth motion. Single file/tooth and single use. Choose the size correctly: The choice depends in size of the canal. Significant improvement in cyclic fatigue and centering ability. Associated with postoperative pain if not used with glidepath rotary files Ghassan Yared, 2007. Significant improvement to centering ability Fifth generation. The fifth generation of shaping files has been designed such that the center of mass and/or the center of rotation are offset. This offset design serves to further minimize the engagement between the file and dentin 6 th generation (3D shaping) S Shape in cross section. Create envelope motion. XP-endo Shaper 3D cleaning, disruption of biofilm, centering ability. XP-endo Shaper XP-endo Shaper New files are for conservative preparation Suggested guide Start using files from 3rd generation. Do simple literature review about the file. Prioritize safety over price. Compare other features. Benefit cost ratio has to be acceptable. Attend workshop with a specialized endodontist who uses this file. Start in simple cases until you adopt to the new one. How to choose your rotary files General guide Guiding map ( within you) Many sizes, multiple reuse, Efficiency, predictability Conservative preparation acceptable price. single size and single use Ultra flexibility files 3D Shaping 3rd generation 4 th generation 6th generation All excellent fatigue resistance and centering ability. The modern endodontics: Now Traditional access Conservative access
