The ProTaper NiTifiles (Dentsply Maillefer; Ballaigues, Switzerland) represent a revolutionarygeneration of instruments for shaping root canals. This post will review the ProTaper geometries, thendescribe the ProTaper concepts, techniques and finishing criteria that may beutilized to fulfill the mechanical and biological objectives for shapingcanals. Learning the ProTaper concept will lead to discovery then appreciationfor this six instrument set, comprised of just three Shaping and three Finishingfiles.
The canals of thismandibular molar were shaped with ProTaper files and three-dimensionallyfilled. Note the flowing shapes, apical one-third curvatures and multipleportals of exit.
Protaper geometries
The following will describethe ProTaper geometries and specific features that make these Shaping andFinishing files remarkably unique.
The Shaping Files
Shaping File # 1 andShaping File # 2, termed S1 and S2, have purple and white identification rings on their handles, respectively. The S1 and S2 files have D0 diameters of 0.17 mm and 0.20 mm, respectively,and their D14 maximal flute diametersapproach 1.20 mm (Fig. 19.3). The Auxiliary Shaping File, termed SX, has no identification ring on its gold-coloredhandle and, with a shorter overall length of 19 mm, provides excellent accesswhen space is restrictive. Because SX has a much quicker rate of taper between D1 and D9 as compared to the other ProTaper Shaping files, it is primarily used,after S1 and S2, to optimally shape canals in coronally brokendown or anatomically shorter teeth. The SX file has a D0 diameterof 0.19 mm and a D14 diameterapproaching 1.20 mm.
ProgressivelyTapered Design
A unique feature ofthe ProTaper Shaping files is each instrument has multiple “increasing”percentage tapers over the length of its cutting blades. This progressivelytapered design serves to significantly improve flexibility, cutting efficiency,and safety.Fortuitously, a progressively tapered design typically reduces thenumber of recapitulations needed to achieve length, especially in smalldiameter or more curved canals. As an example, the SX file exhibits nine increasingly larger tapersranging from .035 to .19 between D1 and D9, and a fixed .02 taperbetween D10 and D14. The S1 file exhibits twelve increasingly larger tapers ranging from .02 to .11between D1 and D14.
The S2 file exhibits nine increasingly larger tapers rangingfrom .04 to .115 between D1 and D14. This design feature allows each shaping fileto perform its own “crown down” work. One of the benefits of a progressively taperedshaping file is that each instrument engages a smaller zone of dentin whichreduces torsional loads, file fatigue and the potential for breakage.
The Finishing Files
Three Finishing filesnamed F1, F2 and F3 have yellow, red and blue identification rings on their handles correspondingto D0 diameters of 0.20 mm,0.25 mm, and 0.30 mm, respectively. Additionally, F1, F2, and F3 have fixed tapers betweenD1and D3 of .07, 08, and .09, respectively.
The ProTaper technique
Canal preparation isimproved when instruments pass through the access opening, effortlessly slidedown smooth axial walls and are easily inserted into the orifice. The potentialto consistently shape canals and clean root canal systems is significantlyenhanced when the coronal two-thirds of the canal is first pre-enlarged followedby preparing its apical one-third.
Scout the coronaltwo-thirds
When straight-lineaccess is completed, the pulp chamber should be filled with a viscous chelatorand/ or irrigant. Based on pre-operative radiographs, ISO 0.02 tapered sizes #10and #15 K-files are measured and precurved to match the anticipated full lengthand curvature of the rootcanal. However, in this method of canalpreparation, these instruments are initially limited to the coronal two-thirds of a root canal. The#10 and #15 K-files are utilized within any portion ofthe canal until they are loose and a smooth reproducible‘glide path’ is confirmed. The loose depth of the #15K-file is measured and this length transferred to theProTaper S1 and S2 instruments.
Shape the coronaltwo-thirds
Once a reproducibleglide path is verified this portion of the canal should be pre-enlarged byfirst utilizing S1 then S2. Prior to initiating shaping procedures, the pulpchamber is filled with a 5.25% solution of NaOCl. Without pressure, and in oneor more passes, the ProTaper Shaping instruments are allowed to passively ‘float’into the canal and ‘follow’ the glide path. To optimize safety and efficiency,the Shaping instruments are used, like a ‘brush’, to laterally and selectivelycut dentine on the outstroke. A brush-cutting action creates lateral space,which will facilitate the larger, stronger and more active cutting blades onthe Shaping instruments to safely and progressively move deeper into the canal.If any ProTaper instrument ceases to advance within the verified portion of acanal, withdraw it, and recognize that intrablade debris has deactivated andpushed the instrument off the wall of the canal.
Upon removing eachShaping instrument, visualize where the debris is located along its cuttingblades to better appreciate the region within the canal that is being prepared.Following the use of each Shaping instrument, irrigate, recapitulate with a #10file to break up debris and move it into solution, then reirrigate.
Without pressure, andin one or more passes, S1, then S2, is used in this manner until the depth ofthe #15 K-file is reached.
Scout the apicalone-third
When the coronal two-thirdsof the canal is shaped, then attention can focus on apical one-thirdprocedures. With the pulp chamber filled with a viscous chelator or irrigant,the apical one-third of the canal is fully negotiated and enlarged to at leasta size #15 Kfile, working length confirmed and patency established. At thistime, a decision must be made between whether to finish the apical one-thirdwith rotary or hand instruments. If a new and straight #15 file can gently ‘slide’and passively ‘glide’ to length, then rotary instruments will generally followthis confirmed and reproducible glide path. However, certain canals exhibitanatomical challenges that necessitate a reciprocating handle motion in orderto move pre-curved #10 and #15 files to length. When there is an irregular glidepath then the apical one-third of a canal may be finished with pre-curved
ProTaper hand instruments.
Shape the apicalone-third
When the apical one-thirdof the canal has been scouted and a glide path created, then the pulp chamberis filled with NaOCl. The ProTaper sequence is to carry the S1, then the S2, tothe full working length. Float, follow and brush as previously described untilthe terminus of the canal is reached. S1, then S2, will typically move to lengthin one or more passes depending on the length, diameter and curvature of thecanal. Following each ProTaper instrument, irrigate, recapitulate with a #10 file,then re-irrigate. After using the Shaping instruments, particularly in morecurved canals, working length should be reconfirmed, as a more direct path to theterminus has been established. At this stage of treatment, the preparation canbe finished using one or more of the ProTaper Finishing instruments in a ‘nonbrushing’manner. The F1 is selected and passively allowed to move deeper into the canal,in one or more passes, until the terminus is reached. When the F1 achieveslength, the instrument is removed, its apical flutes are inspected and if theyare loaded with dentine, then visual evidence supports the shape is cut. Followingthe use of F1, flood the canal with irrigant, recapitulate and confirm patency,then re-irrigate to liberate debris from the canal.
ProTaper finishingcriteria
Following the use ofthe 20/07 F1, the ‘ProTaper Finishing Criteria’ is to gauge the size of theforamen with a 20/02 tapered K-file to determine if this instrument is snug orloose at length. If the #20 Kfile is snug at length then the canal is fully shapedand, if irrigation protocols have been followed, ready to fill.
Following the use ofF1, if the #20 K-file is loose at length, then gauge the size of the foramenwith a 25/ 02 tapered K-file. If the #25 file is snug at length, then the canalis fully shaped and ready to fill. If the #25 file is short of length, proceedto the 25/08 F2 and, when necessary, the 30/09 F3, gauging after each Finisher withappropriately sized hand files. If the #30 file is loose at length, then use analternative NiTi rotary line or manual files to finish the apical extent ofthese larger, easier and more straightforward canals. ProTaper shapes are easyto fill utilizing a ProTaper matching gutta percha master cone in conjunctionwith a warm vertical condensation technique.
Video of Protaper Demonstration on a Block
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