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Endodontic Topics 2005, 10, 151–154 All rights reserved
Copyright r Blackwell Munksgaard ENDODONTIC TOPICS 2005 1601-1538
Root canal instrumentation with ProFilet instruments ADAM LLOYD The history behind the introduction of rotary nickel–titanium instruments of increasing taper is outlined along with a logical sequence of crown-down canal that can be applied to a variety of cases. Clinically applicable canal instrumentation is explained for small, medium and large canals with actual examples prepared with the same technique.
Background The introduction of engine-driven instruments in tapers greater than the standard 2% taper in 1992 by Dr Wm. Ben Johnson substantially changed the way root canal preparation was accomplished. These instruments made it possible to create an appropriately flared canal shape without the need for time-consuming serial stepback shaping procedures. Furthermore, the use of the ProFile (Dentsply Tulsa Dental, Tulsa, OK, USA) instrument sequence allowed greater predictability in canal shape allowing earlier and deeper penetration of irrigating solutions and increased flow dynamics when using thermoplasticized obturation materials, such as ThermaFil (Dentsply Tulsa Dental).
Instrument usage and design The design of the original ProFile instruments was a considerable departure from the ISO hand file specification because the tip size corresponded to a uniform increase of 29% between instruments and accordingly the nomenclature of each instrument in the series ranged from 2 to 10. The rationale behind this paradigm shift provided the operator with more instruments of smaller tip size to be used in the delicate apical anatomy, while fewer larger instruments were necessary coronally, where flexibility is of less concern. The series also decreased the number of instruments used in canal preparation. These Series 29 ProFiles
(Dentsply Tulsa Dental) were introduced in 1993 with a .04 taper, while instruments with .06 taper were added later. In due course, a more traditional ISO series of ProFile instruments with conventional sizes was manufactured and marketed by Dentsply Maillefer (Ballaigues, Switzerland) along with a series of Orifice Shapers. The latter instruments are similar to ProFile but, in general, have large tip diameters, shorter cutting blades and greater tapers. More recently, ProFile instruments with a .02 taper were introduced to provide a comprehensive range of tapers that are capable of dealing with most canals shapes. The use of Series 29 instruments initially presented some difficulties, with the non-standard tip size, the change in the file numbering system and the use of metallic colours designating size. These factors produced a system that had a steep learning curve and as such Series 29 ProFiles were mostly the purview of specialists. The introduction of ISO tip diameters simplified their adoption to a wider range of general dentists and specialists. The flutes of ProFile instruments have radial lands that cut radicular dentine with a neutral rake angle, planing the walls smooth and minimizing canal transportation. A tip with no sharp transitional line angles further enables the instrument to remain centred around canal curvature virtually eliminating ledge formation. The flutes are cut deep into the core from tip to shank allowing greater flexibility at larger cross-sectional diameters, while allowing larger amounts of debris to be removed. The cross-section of
151
Lloyd the instrument is referred to as a U-blade design, and hence has passive cutting ability (Fig. 1).
Preparation sequence The crown-down preparation technique recommended today for most rotary nickel–titanium systems was
Fig. 1. SEM of ProFile instrument showing radial lands and safe-ended tip (courtesy of Dr Ove A. Peters).
popularized by ProFile rotary instruments. Gates– Glidden drills were supplemented or replaced with ProFile Orifice Shapers. Orifice Shapers share the same U-blade design permitting straight-line access to the coronal and middle thirds without encroaching on the so-called danger zone, which may occur with Gates– Glidden drills. The use of viscous chelating agents and Orifice Shapers can effectively extirpate the vital pulp from the canal. After coronal flaring with Orifice Shapers and initial scouting of the canal shaping with the ProFile instruments can commence. Several instrumention sequences have been described for ProFile, including the variable taper sequence, the variable tip sequence and a sequence that alternates between .06 and .04 tapers. The technique described here consists of using decreasing tip sizes and and then decreasing taper in accordance with current recommendations by the manufacturer (see concept box in Table 1). The concept of bringing a predefined taper to the canal terminus is thus realized through use of ProFile .06 followed by .04 taper instruments. ProFile instru-
Table 1. Concept box: canal preparation using ProFile rotary files
152
Colours represent ISO instrument sizes Lubrication with viscous chelator during canal scouting and coronal flaring Sodium hypochlorite irrigant used throughout cleaning and shaping procedure Use 17% EDTA during apical preparation and as rinse before canals are dried
ProFile canal instrumentation with sodium hypochlorite throughout the remainder of the treatment. The estimated working length (EWL) is recorded from a well-angulated periapical radiograph and transferred to the rubber stops of each instrument or measured at the respective markings on the instruments’ shaft.
Small canals
Fig. 2. Maxillary first molar shaped with ProFile Series 29.06 files to canal terminus. Additional flaring in palatal canal performed with Gates–Glidden drills.
Fig. 3. Canal shaping of mandibular second molar with combination .04 and .06 ProFile Series 29 instruments. Acute apical curve on distal canal demonstrates ability of rotary file to negotiate such anatomical variants.
ments with a .06 taper are used to refine and ensure a more consistent flare once the apical preparation is complete. By using .06 and then .04 tapers, friction between root canal walls and the rotating instrument is reduced and taper-lock is avoided. This phenomenon is believed to occur when the taper of the file closely matches that of the canal, producing greater amounts of torque on the instrument and increasing the risk of instrument breakage. Larger tip diameters are chosen initially to prepare the middle and coronal third of the canal, effectively decreasing binding of smaller instruments used later in the sequence. It should be noted that initial canal entry is aided by the use of a lubricant, with copious irrigation
A size 25 .06 instrument is used between 150 and 300 RPM while allowing the instrument to progress passively into the canal. A light pecking motion is recommended, withdrawing and advancing the instrument until it will not proceed further and never more than approximately 3 mm short of the EWL. The flutes are cleaned and inspected for unwinding. The canal is irrigated and the glide path confirmed by recapitulating with a small hand instrument, followed by a size 20 .06 rotary instrument that is advanced with the same technique to working length. A size 20 .04 ProFile shapes the apical third and is followed by a size 25 .04 instrument. Hand files are used to gauge the cross-sectional diameter at the canal terminus (master apical file, MAF) and confirm the presence of acceptable taper. Final flaring is completed with a .06 ProFile with a tip diameter one size smaller than the hand file that bound at the working length (MAF, see concept box in Table 1). Again, the use of a .06 rotary instrument ensures taper in the apical third and blends the various stages of preparation in an attempt to create a uniform taper from orifice to apex. A circumferential movement may be used to flare the coronal canal third canal further for additional taper. Examples of the kinds of taper and shape of canals shaped with ProFile rotary instruments are shown in Figs 2 and 3.
Other sequences One sequence for preparation of medium and large canals is shown in the concept box in Table 1. As stated earlier, alternative sequences are possible and have been advocated, including the use of a single taper throughout, varying only the tip diameter, and using the same tip diameter but alternating the taper. In particular the use of the five instruments with .06 tapers, ranging from 0.4 to 0.15 mm tip diameter, is a rapid way to shape larger and rather straight canals. In sum-
153
Lloyd mary, ProFile instruments with the possibility of variation in sequences allows for variations in apical anatomy, with the tip size chosen according to the size at the terminus.
The Gold standard The ProFile series has been the most widely researched nickel–titanium rotary instrument in endodontics over the last 10 years establishing it as the gold standard against which others are measured. Introduction of these rotary instruments has enabled practitioners to provide a more predictable level of care to patients in a more timely and reproducible manner and has caused a paradigm shift in the way endodontic treatment is accomplished and has raised the standard of care.
154
Further reading 1. Blum JY, Machtou P, Micallef JP. Location of contact areas on rotary Profile instruments in relationship to the forces developed during mechanical preparation on extracted teeth. Int Endod J 1999: 32: 108–114. 2. Kavanagh D, Lumley PJ. An in vitro evaluation of canal preparation using Profile .04 and .06 taper instruments. Endod Dent Traumatol 1998: 14: 16–20. 3. Schrader C, Ackermann M, Barbakow F. Step-by-step description of a rotary root canal preparation technique. Int Endod J 1999: 32: 312–320. 4. Schrader C, Peters OA. Analysis of torque and force during step-back with differently tapered rotary endodontic instruments in vitro. J Endod 2005: 31: 120– 123. 5. Yared GM, Bou Dagher FE, Machtou P. Influence of rotational speed, torque and operator’s proficiency on ProFile failures. Int Endod J 2001: 34: 47–53. 6. Zmener O, Banegas G. Comparison of three instrumentation techniques in the preparation of simulated curved root canals. Int Endod J 1996: 29: 315–319.
Copyright r Blackwell Munksgaard ENDODONTIC TOPICS 2005 1601-1538
Root canal instrumentation with ProFilet instruments ADAM LLOYD The history behind the introduction of rotary nickel–titanium instruments of increasing taper is outlined along with a logical sequence of crown-down canal that can be applied to a variety of cases. Clinically applicable canal instrumentation is explained for small, medium and large canals with actual examples prepared with the same technique.
Background The introduction of engine-driven instruments in tapers greater than the standard 2% taper in 1992 by Dr Wm. Ben Johnson substantially changed the way root canal preparation was accomplished. These instruments made it possible to create an appropriately flared canal shape without the need for time-consuming serial stepback shaping procedures. Furthermore, the use of the ProFile (Dentsply Tulsa Dental, Tulsa, OK, USA) instrument sequence allowed greater predictability in canal shape allowing earlier and deeper penetration of irrigating solutions and increased flow dynamics when using thermoplasticized obturation materials, such as ThermaFil (Dentsply Tulsa Dental).
Instrument usage and design The design of the original ProFile instruments was a considerable departure from the ISO hand file specification because the tip size corresponded to a uniform increase of 29% between instruments and accordingly the nomenclature of each instrument in the series ranged from 2 to 10. The rationale behind this paradigm shift provided the operator with more instruments of smaller tip size to be used in the delicate apical anatomy, while fewer larger instruments were necessary coronally, where flexibility is of less concern. The series also decreased the number of instruments used in canal preparation. These Series 29 ProFiles
(Dentsply Tulsa Dental) were introduced in 1993 with a .04 taper, while instruments with .06 taper were added later. In due course, a more traditional ISO series of ProFile instruments with conventional sizes was manufactured and marketed by Dentsply Maillefer (Ballaigues, Switzerland) along with a series of Orifice Shapers. The latter instruments are similar to ProFile but, in general, have large tip diameters, shorter cutting blades and greater tapers. More recently, ProFile instruments with a .02 taper were introduced to provide a comprehensive range of tapers that are capable of dealing with most canals shapes. The use of Series 29 instruments initially presented some difficulties, with the non-standard tip size, the change in the file numbering system and the use of metallic colours designating size. These factors produced a system that had a steep learning curve and as such Series 29 ProFiles were mostly the purview of specialists. The introduction of ISO tip diameters simplified their adoption to a wider range of general dentists and specialists. The flutes of ProFile instruments have radial lands that cut radicular dentine with a neutral rake angle, planing the walls smooth and minimizing canal transportation. A tip with no sharp transitional line angles further enables the instrument to remain centred around canal curvature virtually eliminating ledge formation. The flutes are cut deep into the core from tip to shank allowing greater flexibility at larger cross-sectional diameters, while allowing larger amounts of debris to be removed. The cross-section of
151
Lloyd the instrument is referred to as a U-blade design, and hence has passive cutting ability (Fig. 1).
Preparation sequence The crown-down preparation technique recommended today for most rotary nickel–titanium systems was
Fig. 1. SEM of ProFile instrument showing radial lands and safe-ended tip (courtesy of Dr Ove A. Peters).
popularized by ProFile rotary instruments. Gates– Glidden drills were supplemented or replaced with ProFile Orifice Shapers. Orifice Shapers share the same U-blade design permitting straight-line access to the coronal and middle thirds without encroaching on the so-called danger zone, which may occur with Gates– Glidden drills. The use of viscous chelating agents and Orifice Shapers can effectively extirpate the vital pulp from the canal. After coronal flaring with Orifice Shapers and initial scouting of the canal shaping with the ProFile instruments can commence. Several instrumention sequences have been described for ProFile, including the variable taper sequence, the variable tip sequence and a sequence that alternates between .06 and .04 tapers. The technique described here consists of using decreasing tip sizes and and then decreasing taper in accordance with current recommendations by the manufacturer (see concept box in Table 1). The concept of bringing a predefined taper to the canal terminus is thus realized through use of ProFile .06 followed by .04 taper instruments. ProFile instru-
Table 1. Concept box: canal preparation using ProFile rotary files
152
Colours represent ISO instrument sizes Lubrication with viscous chelator during canal scouting and coronal flaring Sodium hypochlorite irrigant used throughout cleaning and shaping procedure Use 17% EDTA during apical preparation and as rinse before canals are dried
ProFile canal instrumentation with sodium hypochlorite throughout the remainder of the treatment. The estimated working length (EWL) is recorded from a well-angulated periapical radiograph and transferred to the rubber stops of each instrument or measured at the respective markings on the instruments’ shaft.
Small canals
Fig. 2. Maxillary first molar shaped with ProFile Series 29.06 files to canal terminus. Additional flaring in palatal canal performed with Gates–Glidden drills.
Fig. 3. Canal shaping of mandibular second molar with combination .04 and .06 ProFile Series 29 instruments. Acute apical curve on distal canal demonstrates ability of rotary file to negotiate such anatomical variants.
ments with a .06 taper are used to refine and ensure a more consistent flare once the apical preparation is complete. By using .06 and then .04 tapers, friction between root canal walls and the rotating instrument is reduced and taper-lock is avoided. This phenomenon is believed to occur when the taper of the file closely matches that of the canal, producing greater amounts of torque on the instrument and increasing the risk of instrument breakage. Larger tip diameters are chosen initially to prepare the middle and coronal third of the canal, effectively decreasing binding of smaller instruments used later in the sequence. It should be noted that initial canal entry is aided by the use of a lubricant, with copious irrigation
A size 25 .06 instrument is used between 150 and 300 RPM while allowing the instrument to progress passively into the canal. A light pecking motion is recommended, withdrawing and advancing the instrument until it will not proceed further and never more than approximately 3 mm short of the EWL. The flutes are cleaned and inspected for unwinding. The canal is irrigated and the glide path confirmed by recapitulating with a small hand instrument, followed by a size 20 .06 rotary instrument that is advanced with the same technique to working length. A size 20 .04 ProFile shapes the apical third and is followed by a size 25 .04 instrument. Hand files are used to gauge the cross-sectional diameter at the canal terminus (master apical file, MAF) and confirm the presence of acceptable taper. Final flaring is completed with a .06 ProFile with a tip diameter one size smaller than the hand file that bound at the working length (MAF, see concept box in Table 1). Again, the use of a .06 rotary instrument ensures taper in the apical third and blends the various stages of preparation in an attempt to create a uniform taper from orifice to apex. A circumferential movement may be used to flare the coronal canal third canal further for additional taper. Examples of the kinds of taper and shape of canals shaped with ProFile rotary instruments are shown in Figs 2 and 3.
Other sequences One sequence for preparation of medium and large canals is shown in the concept box in Table 1. As stated earlier, alternative sequences are possible and have been advocated, including the use of a single taper throughout, varying only the tip diameter, and using the same tip diameter but alternating the taper. In particular the use of the five instruments with .06 tapers, ranging from 0.4 to 0.15 mm tip diameter, is a rapid way to shape larger and rather straight canals. In sum-
153
Lloyd mary, ProFile instruments with the possibility of variation in sequences allows for variations in apical anatomy, with the tip size chosen according to the size at the terminus.
The Gold standard The ProFile series has been the most widely researched nickel–titanium rotary instrument in endodontics over the last 10 years establishing it as the gold standard against which others are measured. Introduction of these rotary instruments has enabled practitioners to provide a more predictable level of care to patients in a more timely and reproducible manner and has caused a paradigm shift in the way endodontic treatment is accomplished and has raised the standard of care.
154
Further reading 1. Blum JY, Machtou P, Micallef JP. Location of contact areas on rotary Profile instruments in relationship to the forces developed during mechanical preparation on extracted teeth. Int Endod J 1999: 32: 108–114. 2. Kavanagh D, Lumley PJ. An in vitro evaluation of canal preparation using Profile .04 and .06 taper instruments. Endod Dent Traumatol 1998: 14: 16–20. 3. Schrader C, Ackermann M, Barbakow F. Step-by-step description of a rotary root canal preparation technique. Int Endod J 1999: 32: 312–320. 4. Schrader C, Peters OA. Analysis of torque and force during step-back with differently tapered rotary endodontic instruments in vitro. J Endod 2005: 31: 120– 123. 5. Yared GM, Bou Dagher FE, Machtou P. Influence of rotational speed, torque and operator’s proficiency on ProFile failures. Int Endod J 2001: 34: 47–53. 6. Zmener O, Banegas G. Comparison of three instrumentation techniques in the preparation of simulated curved root canals. Int Endod J 1996: 29: 315–319.
