1/21 issn 2193-4673 • Vol. 17 • Issue 1/2021 roots international magazine of endodontics study Cyclic fatigue resistance of several glide path rotary and reciprocating fi les technique Improved endodontic effi ciency with Er:YAG AutoSWEEPS modality practice management Slow down everyone— dentistry does not need to be done at speed

editorial | Magda Wojtkiewicz Managing Editor Modern endodontics: What is next? In the field of endodontics, as in many other fields of dentistry, developments in science and research have enabled dental professionals to succeed in diagnosis, treatment planning and treatment. The future of den- tistry and endodontics is facing a change curve. Change is the only constant in the future, and those who adapt well and embrace innovation can succeed. Technolog- ical advancements make complex procedures easier and more successful, but demand new approaches and changes in the perception of root canal therapy. Endodontics has experienced major changes. Firstly, the rapid spread of information and technology has transformed endodontics forever in the best possible way. Such a transformation has made endodontic pro- cedures safer, easier and more predictable and thus less stressful for the patient and dentist. Secondly, end- odontics has been incorporated into an interdisciplin- ary approach to dentistry. As endodontic treatment has become more predictable, more dental professionals have taken it into consideration in preparing complex treatment plans. Thirdly, increased longevity means that patients want to keep their own teeth for as long as possible, enjoy good health and have quality of life. Fourthly, the success rate and predictability of end- odontic treatment have made it serious competition for implant treatment. These changes have started a new era in endodontics, one in which root canal therapy is no longer regarded as a risky procedure with unpredictable results. New, innovative root canal therapy methods have now re- placed conventional procedures, being safer and giving long-lasting results. Cone beam computed tomogra- phy, nickel–titanium files, apex locators, irrigation and microscopes are only some new technologies which have changed completely the way dentists perform root canal therapy. The complexity of root canal systems is still a chal- lenge for the newer and more advanced technologies to solve. The rapid developments in science and tech- nology promise a bright future for root canal therapy. Advancements in 3D printing, microscopic equipment and sonic frequencies can benefit root canal procedures immensely. Magda Wojtkiewicz Managing Editor roots 1 2021 03

Reciproc family Take the one that fits best The universal and flexible instrument for the majority of cases. The instrument particularly efficient for retreatments. vdw-dental.com

trends & applications | 5a 5b 5c 5d 5e 5f 5g 5h 5i 5j 5k 5l Figs. 5a–l: Incisal access allows for maximum peri-cervical dentine preservation. CBCT can be used for access cavity planning in calcifi ed cases (a–d). All cases are immediately restored at the time of obturation. Four-year (e–h) and two-year (i–l) follow-ups showing complete radiographic healing. Both teeth were asymptomatic and functional. (Cases treated by Dr Viraj Vora) The quality of the evidence for the long-term effectiveness of the mechanical objectives of endodontic therapy is weak, and thus treatment protocols are highly variable among clinicians and often the treatment approaches that are the most expedient prevail. Traditional objectives have been focused on maximising the visual field of access cavity preparation and preparing canals to certain dimensions to facilitate a certain appearance of the radiographic obtura- tion, which is used as a proxy for cleanliness of the canal systems.6, 7 The long-term survival of endodontically treated teeth (ETT) has been investigated through epidemiology.8–16 These studies suggest that maintaining dentine and achiev- ing appropriate restorative management during endodontic procedures are two of the most critical factors for tooth sur- vival and longevity, which is really what our patients desire. Minimally invasive endodontics stem from the restorative requirements for ETT to survive in the long term. Some approaches to achieving adequate immediate restoration of ETT were described in our previous article.17 The current article discusses the armamentarium available to the clini- cian to maintain residual dentinal structure during endodon- tic therapy without compromising root canal disinfection and obturation. The two main opportunities for maintain- ing dentinal structure present to the clinician during access cavity preparation and root canal instrumentation. Armamentarium for conservative access cavity preparation Access cavity preparation is defined as the removal of a cor- onal portion of the pulp complex to facilitate canal location and debridement.18 Despite the lack of compelling clinical roots 1 2021 07

trends & applications | 7a 7c 7b 7d Figs. 7a–d: Caries-directed mesialised access (a). The soffit was preserved for added strength (red arrow; b). Straight-line access to the two mesiobuccal orifices (c) and two distobuccal orifices (d) was achieved. The tooth was immediately restored at the time of obturation. (Case treated by Dr Bobby Nadeau) caries and restorations.23 These areas should therefore be leveraged during access cavity preparation (Figs. 6a–c). The premise of classic endodontic access is to gain straight- line access into the root canal systems usually through all coronal structures or dental materials, whereas carefully removing materials of no value (leveraging) allows for better visualisation and greater volume of residual dentine, which is the foundation for fracture resistance and long-term retention of ETT.25, 26 and onlays. It involves cutting a larger outline in restorative materials down to the level at which dentine is encoun- tered (Figs. 12a–e & 13a–d).23 The clinician can then assess the location and angulation of the entry point to the pulp chamber based on its anticipated location and dentine colour map. The stepped access can also leverage direct restorative materials, leading to an unobstructed path to dentine, which facilitates conservative access to the pulp chamber (Figs. 14a–f & 15a–f). Leveraged access designs often lead to the preservation of the soffit. The soffit consists of undermined dentine at the level of the pulp chamber roof, and this is thought to provide additional strength (Figs. 7a–d).20 Advancements in dental materials include modern flexible martensitic heat-treated NiTi rotary files with regressive taper that can be prebent (Fig. 8), high magnification and illumination, and smaller burs allowing access to canal orifices even in the absence of true straight-line access. Data from 2D and 3D (CBCT) radiography can also be utilised to approximate the depth of the pulp chamber and design the access cavity. Figures 7a–d and 9a–j are examples of caries-/restorative- leveraged mesialised/distalised access designs. Buccally and lingually located structures that can be leveraged can also dictate the access entry point (Figs. 10a–f & 11a–f). 8 Stepped access The stepped access cavity design can be used in both an- terior and posterior teeth. It is the design of choice for most access cavities through indirect restorations like crowns Fig. 8: Modern flexible martensitic heat-treated NiTi rotary files can be prebent for easier insertion in contracted access cavities and for predicable root canal negotiation. The DC Taper rotary file system (SS White Dental) is an example of rotary files with regressive taper. roots 1 2021 09

trends & applications | 10a 10b 10c 10d 10e 10f Figs. 10a–f: Initial situation (a). The restorative material (b) was leveraged, leading to a buccally positioned access cavity (c & d). Radiograph of the tooth, which was immediately restored at the time of obturation. (e). The one-year follow-up showed radiographic healing, and the patient was asymptomatic and functional (f). (Case treated by Dr Dale Jung) biological goals for long-term success”.6, 28 The focus of such objectives was to create a canal preparation with a diameter that increases coronally and decreases apically. Based on these objectives, an apical size and taper of at least 25/.08 has been recommended in order to allow for deep exchange of irrigating solutions and resistance form 11a 11b 11c 11d 11e 11f Figs. 11a–f: Initial situation: radiograph (a); intra-oral (b). The carious lesion was leveraged, leading to a lingually positioned access cavity (c). A separate access hole was created on the occlusal surface to gain access to the buccal canals (d). A bent instrument was used to clean under the pulpal roof (e). Radiograph of the tooth, which was immediately restored at the time of obturation (f). (Case treated by Dr Dale Jung) roots 1 2021 11

trends & applications | 14a 14b 14c 14d 14e 14f Figs. 14a–f: Stepped access in a maxillary molar with direct restorative material (a & b). A larger outline through the restorative material was cut (c). The mesiobuccal pulp horn was accessed first (d). The access cavity was enlarged enough to gain straight-line access to the remaining canals (e). Radiograph of the tooth, which was immediately restored at the time of obturation (f). (Case treated by Dr Bobby Nadeau) ignoring the biological objectives of disinfection and obtu- ration, particular attention should be given to conserving residual root canal dentine. This section discusses the armamentarium used for conservative root canal instru- mentation and disinfection and obturation of such canals. Shaping and obturation Perhaps the most critical factor involved in achieving conservative root canal shaping is the clinician’s choice of instruments. Large, stiff instruments that will remove excessive dentine or will increase the likelihood of root 15a 15b 15c 15d 15e 15f Figs. 15a–f: Stepped access in a maxillary molar with direct restorative material (a & b). A larger outline through the restorative material was cut to allow unobstructed access to the underlying dentine (c & d). Radiograph of the tooth, which was immediately restored at the time of obturation (e). The two-year follow-up showed radiographic healing, and the patient was asymptomatic and functional (f). (Case treated by Dr Viraj Vora) roots 1 2021 13

trends & applications | 18a 19a 19b 19c 18b 19d 19e 19f 19g 19h Figs. 18a & b: In truss access cavities, microsurgical ultrasonic tips (a) and syringe irrigation and suction (b) can be used to clean and disinfect under the truss. (Case treated by Dr Dale Jung) Figs. 19a–h: Access design for minimally restored or non-restored posterior teeth can involve penetration at the level of the mesiobuccal pulp horn and subsequent extension as needed. Straight-line access to the distal canals projects coronally in the mesial direction (red dotted lines; c, e & h). Note the mesial position and angulation of the restored access cavities (c, e & h). (Cases treated by Dr Bobby Nadeau) disinfection and obturation procedures should not be omitted. The use of a 30-gauge tip irrigation needle with a closed end and a side port helps bring irrigating solu- tions deeper into the canal. Since smaller canal prepa- rations may lead to less exchange of irrigating solutions, it is usually recommended to use an inter-appointment medication, such as calcium hydroxide paste, espe- cially if the tooth presents with symptoms, a sinus tract, swelling or a periapical radiolucency of significant size. Thirty-gauge delivery tips that can be prebent are use- ful when delivering inter-appointment medication deep in the canal. Sonic and ultrasonic instruments also help activate irrigating solutions and are a good adjunct for enhanced disinfection. 20a 20b 20c 20d 20e 20f 20g Figs. 20a–f: Upper left first premolar with pulp necrosis (a). The access cavity in virgin or minimally restored premolars is centred within the occlusal surface (b–d). Radiograph of the tooth, which was immediately restored at the time of obturation (e). The four-year follow-up CBCT scan suggested that 3D obturation had been achieved despite the contracted access cavity and minimal shaping (f & g). The patient was asymptomatic and functional. (Case treated by Dr Dale Jung) roots 1 2021 15

trends & applications | 25a 25b 25c 25d Figs. 21a–f: Vertical root fractures associated with overzealous root canal shaping. Fig. 22: Rotary files with regressive taper (top) have a much smaller maximum flute diameter at the level of the orifice (D16) compared with the most widely used rotary files (bottom). (Image: © SS White Dental) Figs. 23a & b: The use of non-standardised medium-fine gutta-percha cones (a) and extra-fine heat tips facilitates obturation when the warm vertical compaction technique is used (b). Figs. 24a–e: A maxillary left first molar with a 12 mm probing (a & b). The canals were minimally instrumented, and the access was immediately restored at the time of obturation (d). The patient was asymptomatic and functional, the deep probing had healed, and there was radiographic healing at the three-year follow-up (e). (Case treated by Dr Dale Jung) Figs. 25a–d: Initial situation (a). Placement of inter-appointment calcium hydroxide medication (b). Conservatively instrumented canals and immediate restoration of the access cavity (c). The patient was asymptomatic and functional, and there was radiographic healing at the three-year follow-up (d). (Case treated by Dr Dale Jung) about Dense obturation to the apical foramen in minimally shaped canals is still a desirable procedural outcome. The com- mon issue clinicians encounter when transitioning to more conservative instrumentation is difficulty during the obtura- tion phase of treatment. While standardised gutta-percha cones are available, there have been issues with the pre- dictability of the fit of these cones. It is the authors’ opinion that the use of smaller, non-standardised gutta-percha cones helps with cone fitting. Most conservatively in- strumented canals can be obturated with laser-verified medium- fine fitted gutta- percha cones (Fig. 23a). The use of small heat tips also helps when warm vertical compac- tion of gutta- percha is used as the obturation technique (Fig. 23b). Figures 24a–e and 25a–d show that radio- graphic healing at follow-ups can be predictably achieved while maintaining maximal residual radicular dentine. Conclusion Patients perceive value for endodontic therapy when it pro- vides a useful service, especially when weighing the in- vestment of time and money required to reach a desirable outcome. The main obstacle facing any clinician when intro- ducing and implementing a new approach to endodontics is the cognitive dissonance he or she may face for the beliefs he or she holds to be true against what he or she currently practises. Access design and canal instrumentation have been continuously changing over the years, and as better and more user-friendly technologies emerge, clinicians can now perform the same clinical steps with a minimal pro- cedural footprint while achieving desirable patient-centred outcomes. Dynamic navigation, using CBCT data, for con- servative endodontic access is on the horizon and will pave the way for an exciting next decade in endodontics. Editorial note: A list of references is available from the publisher. This article originally appeared in Oral Health Magazine, and an edited version is provided here with permission from Newcom Media. Dr Bobby Nadeau graduated with a DDS from Dalhousie University in Nova Scotia in Canada and an MSc in endodontics from the University of Toronto in Canada. He is in full-time private practice in Kingston in Ontario in Canada. Dr Nadeau may be contacted at bobby.nadeau@mail.utoronto.ca. Dr Dale Jung graduated with a degree in biology from Pomona College in Claremont in California in the US. After college, Dr Jung spent two years at the National Institute of Dental and Craniofacial Research in Bethesda in Maryland in the US, where he studied human salivary gland development and authored and co-authored several papers. He then moved back to California to attend the University of California, Los Angeles School of Dentistry to pursue a career in dentistry. During his time at dental school, Dr Jung became interested in the field of endodontics, and after dental school, he pursued his interests at the New York University College of Dentistry in the US, where he earned his certification in endodontics. Dr Viraj Vora graduated with a DDS from the University of Western Ontario (renamed Western University) in London in Canada and with an MSc and a certificate of specialty in endodontics from the University of Michigan in Ann Arbor in the US. Dr Vora is in full-time private practice in Vaughan in Ontario in Canada limited to microscopic conservative endodontics and restorative dentistry. He can be contacted at viraj@endodonticcentre.ca. roots 1 2021 17

case report | 2 3 Fig. 2: Initial radiograph. Fig. 3: Post-op radiograph. about Dr Paulina Piasta-Kiełkiewicz graduated from the Medical University of Warsaw in Poland in 2010. From 2010 to 2011, she completed a postgraduate internship at the medical clinic of the Military University of Technology in Warsaw. Dr Piasta-Kiełkiewicz has completed additional theoretical and practical courses on endodontic treatment. She works in a private clinic in Warsaw focused mainly on endodontics. AD To achieve a successful treatment, all canals have to be cleaned and shaped to the working length. In this case, it was very important to respect the natural curvature of the canals. For this reason, a single-length technique was performed. VDW.ROTATE files were used in the following sequences: 15/.04, 20/.05 and 25/.06 for the mesiobuccal and distobuccal canal; and 30/.04, 35/.04 and 40/.04 for the palatal canal. To prevent canal transportation in the second mesiobuccal canal, the master apical file was 25/.04. A den- tal operating microscope (Leica M320, Leica Microsystems) was a helpful tool during endodontic treatment. Copious irrigation with 5% sodium hypochlorite was per- formed during the shaping and cleaning procedures. Copi- ous irrigation with 5% sodium hypochlorite was performed during the shaping and cleaning procedures. An ultra sonic tip (Endo Chuck, EMS) and sonic powered irrigation tip (EDDY, VDW) were used to activate the irrigants. At the end, the canals were irrigated with 17% EDTA, and this solution was kept in the canals for 2 minutes. The canals were dried with paper points. An epoxy-amine root canal sealer and a master gutta-percha cone were placed in the canals and the canals were obturated using the continuous wave ob- turation technique. Glass ionomer cement was used as a temporary filling material (Fig. 3). The patient was referred for final restoration to his general dental practitioner. REGISTER FOR FREE! DT Study Club – e-learning platform Join the largest educational network in dentistry! www.DTStudyClub.com Tribune Group GmbH is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. Tribune Group GmbH designates this activity for one continuing education credit.

case report | 3 4 Fig. 3: Choosing the sequence via touch screen. (© Coltène/Whaledent) Fig. 4: Course of the root canal in the post-op radiograph. After applying a dental dam and creating an access, we first probed the canals using size 8–15 hand files. With the help of the apex locator, the appropriate working length was quickly established. The actual preparation was done with flexible nickel–titanium (NiTi) files. In the main program of the Jeni endodontic motor, different file systems can be selected via touch screen (Fig. 3). Currently, the HyFlex CM or EDM and the MicroMega One Curve or 2Shape from COLTENE are preset in the software. The Doctor’s Choice program also allows you to store individual sequences of up to eight files, but you cannot use the assistant function of the fully automatic Jeni mode in this section, for exam- ple the fine adjustment of the rotational movement. Since updates can be uploaded at any time via a micro SD card, further alternative configuration options are certainly con- ceivable in the future. In order to be able to explicitly use the recommendation on file changes as well as the automatic rinsing announce- ments, the HyFlex EDM was used in the given case in the following sequence: first a 15/.03 file was used, fol- lowed by a 20/.05 file. The majority of the work in the me- sial and distal canals was performed by the universal file 25/~ HyFlex EDM OneFile. A 40/.04 file was used for the filigree work. With this sequence, all canals were success- fully cleaned and shaped. It was astonishing how easily the file adapted to the chang- ing pressure exerted on the instrument. The dentist simply holds the handpiece while the motor does the rest. With Jeni, endodontic beginners and experts alike can enjoy a completely new treatment experience. It is a bit like driving a high-powered car on autopilot: thanks to its sophisticated technical features, the machine has enough power to cope with uneven surfaces, but automatically corrects its course in order to drive around tight corners. The dentist works constantly with light pressure from coronal to apical, which makes the system extremely efficient. At the same time, it eliminates the small pecking motion normally associated with preparation based on tactile feedback. Root canal ther- apy is therefore much faster and less prone to errors now. However, the most amazing thing of all is that, in Jeni mode, the endodontic motor even knows when it is time to irrigate. After the acoustic signal, the current file was removed from the canal and rinsed with sodium hypo- chlorite and then with chlorhexidine at appropriate intervals. Obturation was performed as usual with gutta-percha points in combination with bioceramic sealer. The final ra- diograph shows the root canal system following the natu- ral anatomy. It had been thoroughly prepared and reliably sealed with gutta-percha (Fig. 4). The satisfied patient was discharged. The long-term results hopefully will be seen in the follow-up. Conclusion Long, narrow root canals pose particular challenges to the resistance and flexibility of modern NiTi files. Digital endodontic assistance systems help the dentist by adjust- ing the variable file movement. The reliable co-pilot thus navigates the dentist step by step through the mechan- ical and chemical preparation. Thanks to the constant processing from coronal to apical, canal shaping is much more efficient and less error-prone than it used to be— almost like driving autonomously with a high-powered car on the autobahn. about Dr Richard Gray returned to USC to complete his endodontic residency, graduating in 2000. Upon completion of his residency, he moved back to Mesa in Arizona, where he opened his endodontic offi ce. In October 2007, Dr Gray was recalled to active duty and sent to Iraq in support of Operation Iraqi Freedom. Dr Gray currently maintains his private practice in Midlothian in Virginia in the US. He might be contacted at apexendo@hotmail.com. roots 1 2021 21

technique | SWEEPS mode (dual-pulse) To resolve this limitation and intensify the bubble collapse within the root canal, a newer approach utilising a recently developed dual-pulse SWEEPS (shock wave-enhanced emission photoacoustic streaming) modality was intro- duced. With the SWEEPS mode, pulses are designed to start with sharp initial intensity peaks that enhance the dynamics of the photoacoustic irrigant streaming process. Moreover, a second laser pulse is applied just before the collapse of the first laser pulse’s bubble.16–18 Figures 2 to 4 show the dual-pulse emission of the SWEEPS modality as measured for the latest-generation SkyPulse Endo Er:YAG laser system (Fotona). The sudden expansion of the second bubble generated by the second laser pulse exerts additional pressure on the initial bubble, leading to its accelerated collapse, during which shock waves are emitted. Furthermore, shock waves are emitted from the collapsing second- ary cavitation bubbles that are formed throughout the entire length of the canal during laser-induced irriga- tion.17 The largest enhancement of shock waves and internal irrigant pressure occurs when the temporal separation ( TSWEEPS) between the two SWEEPS laser pulses does not deviate substantially from the optimal separation time, that is, the resonant time (Tres), corresponding to the time when the second laser pulse of the SWEEPS pulse pair is delivered near the end of the collapse phase of the primary bubble generated by the first laser pulse (Tres ≈ 0.9 × TB; TB = cavitation bubble oscillation time; Fig. 5).17, 19 AutoSWEEPS mode A real-world challenge involved in using SWEEPS in dental practice, however, is posed by the fact that the bubble oscillation time TB critically varies depending not only on the laser parameters that can be controlled but also on the particular endodontic access cavity di- mensions of the treated tooth, TB being longer for smaller cavity dimensions (Fig. 6).17, 19 With this variability in mind, a special AutoSWEEPS laser modality was recently developed,16, 20, 21 in which the temporal separation between the pair of laser pulses is continuously swept back and forth between 200 µs and 650 µs. This ensures that during each sweeping cycle there is always at least a 50 µs wide temporal separation range when the pulses are separated by TSWEEPS ≈ Tres, as needed for optimal enhancement. The sweeping func- tionality also ensures that the optimal conditions are ap- proximately reached along the depth of the access cavity by matching the changing diameter conditions during the AutoSWEEPS cycle. 2 3a 3b 4a 4b Fig. 2: Temporal shape of the latest-generation SkyPulse Endo’s dual-pulse SWEEPS mode with nominal single-pulse durations of 25 µs. Measurement was taken for ESWEEPS = 2 × EL = 2 × 20 mJ at the SWEEPS mode repetition rate of 15 Hz. Figs. 3a & b: Temporal shape of the first pulse of the SWEEPS pulse pair shown in Figure 2 (a). Temporal delivery of the cumulative laser energy during the pulse (b). The pulse duration of 17 µs represents the time when 75% of the total laser pulse energy of EL = 20 mJ has been delivered. Figs. 4a & b: Temporal shape of the first pulse (a) and the second pulse of SWEEPS mode as measured for ESWEEPS = 2 × EL = 2 × 10 mJ at the SWEEPS mode repetition rate of 15 Hz (b). Compared with the standard single-pulse SSP (super- short pulse) modality (also known as PIPS, photon- induced photoacoustic streaming), AutoSWEEPS has been reported to be about 50% more effective in gen- erating pressure within the root canal, resulting in sig- nificantly better penetration of irrigants into the dentinal roots 1 2021 23

is coming to PRAGUE 26–29 May 2022 Prague, Czech Republic www.ROOTS-SUMMIT.com Tribune Group GmbH is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. Tribune Group GmbH designates this activity for 18.5 continuing education credits. This continuing education activity has been planned and implemented in accordance with the standards of the ADA Continuing Education Recognition Program (ADA CERP) through joint efforts between Tribune Group GmbH and Dental Tribune International GmbH.

2 3 case report | Fig. 2: Periapical radiograph of the maxillary right molar. Tooth #18 was to be transplanted to the site occupied by tooth #16. Fig. 3: Tooth #18 transplanted to the site previously occupied by tooth #16. 4 Among the different developments in dentistry that have made possible conservative approaches in endodontic practice are flexible endodontic files with controlled mem- ory alloy and enhanced cyclic fatigue resistance, visual magnification, bioactive endodontic sealers, and sonic and ultrasonic irrigant activators.9–11 The development of these technologies has been crucial for making the conservative endodontic approach possible, prioritising the preserva- tion of dentine, especially in the cervical region.12 Case report A 16-year-old female patient was referred to the office for evaluation of tooth #16 (Fig. 1). The referring dentist asked that we apply all the available resources to save the tooth. The diagnosis was previously treated and symptomatic periapical periodontitis. After detailed examination, it was concluded that the tooth was not restorable. With the par- ents’ and patient’s agreement, we decided on an autoge- nous transplantation of tooth #18 to the site of tooth #16 after its extraction (Fig. 2). The orthodontist had determined that tooth #18 was to be extracted, and it was intended that the patient’s occlusion should be balanced by the end of the orthodontic treatment. Teeth #16 and 18 were Fig. 4: A nylon monofilament flexible splint was used to stabilise the trans- planted tooth in the recipient site. extracted in the least traumatic way possible. After minor bone remodelling of the socket using low-speed burs, the third molar was transplanted to the recipient site (Fig. 3). A nylon monofilament flexible splint was used to keep the tooth in place (Fig. 4). Fifteen days later, the splint was removed, healthy soft tissue was observed, the patient 5a 5b 6 Figs. 5a & b: Fifteen days post-op. Healthy periodontal tissue was evident around the transplanted tooth, before (a) and after (b) splint removal. Fig. 6: Eight-month post-op radiograph. The retromolar area had healed, but the transplanted tooth showed signs of pulp necrosis and periapical disease. roots 1 2021 27

case report | 10a 10b 11 Figs. 10a & b: Adhesive coronal restoration, just before (a) and after (b) removal of the isolation. Fig. 11: Three-year follow-up radiograph. The periapical area had healed. most cited advantages of this procedure is that typically a severely destroyed tooth can be exchanged for a tooth in perfect structural condition.4, 15, 17 When root canal therapy is necessary in the transplanted tooth, it is advisable to plan the treatment according to the status of the coronal and radicular structure. The preser- vation of the dental tissue should be a main goal, including the pursuit of minimally affected tooth resistance against occlusal load and functional stress. One of the greatest risks when performing conservative root canal therapy is that, while working through conservative access openings, the files will work under increased flexural stress; flexural stress will be higher at the entrance of the root canal owing to the lack of straight-line access. Cyclic fatigue might increase also at curvatures, leading to greater trans- portation and changing of original root canal anatomy. If cyclic fatigue is one of the major risks related to conser- vative endodontic openings, the use of files with enhanced cyclic fatigue resistance is advisable.18 Aurum Blue is a four-file root canal instrumentation sys- tem in the stable martensitic structural stage (Fig. 12). The cross section, taper, nickel–titanium alloy and elec- tropolished surface treatment were designed and com- bined together to offer a good balance between cyclic and torsional fatigue resistance and high flexibility. All the files smaller than 25/.05 have a square cross section, and larger sizes have a convex triangular cross section. These files are recommended to be used at 500 rpm with 2 Ncm torque. The CeraSeal calcium silicate endodontic sealer is a use- ful option for the use of the single-cone obturation tech- nique (Fig. 13). This technique greatly facilitates the sealing of the root canal system when conservative endodontic procedures are performed. CeraSeal’s physical charac- teristics render it capable of providing a stable 3D seal,19–21 all without the need for vertical or lateral compaction procedures, whether warm or cold. The single-cone obtu- ration technique can be used safely in combination with calcium silicate cements, owing to their physical and di- mensional stability, good sealing properties, antibacterial potential, biocompatibility and bioactivity, being capable of stimulating periapical tissue repair.20–22 These materi- als are able to set in humid environments; this point is of major relevance considering the fact that dentine has a moisture content of approximately 20% and that working in moisture-saturated environments is a constant in the dental profession.20, 21, 23 Conclusion Considering all the biological and functional advantages of autogenous transplantation of a tooth in comparison with an implant placement and all the possibilities of a minimally invasive approach to endodontic treatment using new tech- nology applied to endodontic devices, files and sealers, autogenous transplantation may be a valid treatment alter- native, especially in young and compliant patients.3 about Dr Jenner Argueta earned his degree in dentistry and master’s degree in endodontics from Universidad de San Carlos de Guatemala, where he achieved multiple awards as an outstanding student. He is a certifi ed researcher at the Guatemalan national council for science and technology and teaches endodontics at the Universidad Mariano Gálvez de Guatemala. Dr Argueta also runs a clinical practice focused on micro-endodontics and micro-restorative dentistry. He was president of the Academia de Endodoncia de Guatemala (endodontic academy of Guatemala) from 2016 to 2020 and is the Guatemalan representative for the Latin American Endodontic Association. Dr Argueta can be contacted at jennerargueta@gmail.com. roots 1 2021 29

study | 2a 2b Figs. 2a & b: Artificial canals used in this study: 16 mm long with the angle of curvature 60° and radius (R) of curvature 2.5 mm (a); 16 mm long with the angle of curvature 90° and radius of curvature 2.5 mm (b). motion, and cut in a clockwise (CW) direction. At the tip, they are 0.14 mm in diameter and have a variable taper: 0.04 mm/mm for the first 3.00 mm from the tip, and the taper becomes smaller in the direction of the handle. CW direction. They are 0.16 mm in diameter at the tip and have a variable, increasing taper: from 0.02 mm/mm at the tip to 0.08 mm/mm at the handle. RACE EVO (FKG Dentaire) is a recently introduced sys- tem of files for canal preparation, and it contains a glide path file of 0.15 mm in diameter at the tip and with a con- stant taper of 0.04 mm/mm. These files are made of an NiTi heat-treated alloy. They have a triangle cross section, are designed to operate in rotary motion at high speed, 800 to 1,000 rpm, and cut in a CW direction. WaveOne Gold Glider files (Dentsply Sirona) are made of a modified heat-treated NiTi alloy called Gold-wire. They have a rhomboid cross section, are designed to operate in reciprocal motion and cut in a counter clockwise (CCW) direction. At the tip, they are 0.15 mm in diameter and have a variable, increasing taper: from 0.02 mm/mm at the tip to 0.06 mm/mm close to the handle. R-PILOT files (VDW) are made of M-Wire. They have an S-shaped cross section, are the first glide path files in the market operating in reciprocal motion and cut in a CCW direction. They are 0.125 mm in diameter at the tip and have a constant taper of 0.04 mm/mm. HyFlex EDM (COLTENE) is a system of files for canal prepa- ration, and it contains a glide path file of 0.10 mm in diameter at the tip and with a constant taper of 0.05 mm/mm. It is manufactured from controlled memory NiTi wire subjected to electric discharges, leading to shaping via melting and vaporisation. The files have a changeable shape cross sec- tion, which is quadratic in the apical part and trapezoidal in the coronal part of the instrument. They are designed to operate in rotary motion and cut in a CW direction. ProGlider files (Dentsply Sirona) are made of a modified NiTi alloy called M-Wire. They have a square cross section, are designed to operate in rotary motion and cut in a Even though they have obvious advantages, NiTi files for mechanical glide path preparation, similarly to NiTi shaping files, can fracture inside the canal. A few factors may be distinguished which influence resistance to fracture: 3 4 Fig. 3: The cyclic fatigue test device submerged in distilled water in a heatproof glass dish placed on the electric stove. Fig. 4: Micro-caliper for measuring fractured instruments. roots 1 2021 31

study | 5a Figs. 5a & b: Mean time to fracture (in seconds) for the files operating at a 60° curvature (a) and a 90° curvature (b). according to mathematical rules. The broken fragment of each file was measured with a digital caliper (Magnusson; Fig. 4) to check the positioning of each file in the canal. The producer declares the measurement accuracy to be 0.02 mm. The same measuring devices (thermometer, stopwatch and caliper) were used in the same way for all files to assure measurement repeatability. Therefore, any potential measurement mistakes relate to all tested glide path files and did not interfere with the final results. the compared variables. When statistically significant dif- ferences were noted, the post hoc Games–Howell test was used. It helped to check exactly which files were statisti- cally different. The Wilcoxon signed-rank test was used to look for statistically significant differences between the files while comparing their time to fracture in the 60° and 90° curvatures. The level of statistical significance was set at p < 0.05. Results Statistical analysis Statistical analysis was performed with IBM SPSS Statistics (Version 25). The Kruskal–Wallis test showed statistically significant differences between files within the scope of The mean time to fracture and standard deviation are shown in Table 1. The post hoc test analysis showed that, for the 60° curvature, the mean time to fracture for the Endostar EP Easy Path files was statistically significantly 5b roots 1 2021 33

study | 6e 6f The files were tested in the type of motion and at the rota- tion speed suggested as basic by the producers of each of the instruments. The time to fracture was not related to the number of rotations to fracture, even though such data can be found in many papers.15, 16 This was not done because precise calculation of rotations to fracture for files operating in reciprocal motion (WaveOne Gold Gilder and R-PILOT) is not possible. In order to convert time to fracture into number of rotations to fracture for reciprocal motion files, we would have had to obtain precise data: the rotation speed for the partial CW rotation of the instrument and the rotation speed for the partial CCW rotation, the length of the pause between these two types of rotations (CW and CCW), which is necessary to change the direction of rotation in the handpiece, and finally accurate angles of partial rotation by which the file moves in both directions (CW and CCW) in a given reciprocal motion.17, 18 This data is not available; therefore, calculation of number of rota- tions to fracture for reciprocal motion was not possible. Providing just time to fracture for the RACE EVO files pro- duces fairly poor results because they operate at a very high speed, 800 rpm. As research has shown, with a higher rotation speed, the time to fracture becomes shorter in a cyclic fatigue test.19, 20 The producer of these files recom- mends working at such high speed, but during clinical work, it must be remembered that the time to fracture of these files in curved canals will be shorter. The tested files have different designs (size, taper and cross section) and are made of NiTi alloy that has under- gone different heat treatments. In fatigue tests, the size of a file in the centre of the curvature in which it operates has an influence on the results.21 The width of the files at the point of fracture is not the same, because they have differ- ent sizes and tapers. There is no available precise data for the files of varying taper, their exact size at each millime- tre from the tip. Therefore, when comparing files, we must take into consideration that they could fracture in a place where their size is different. As Plotino et al. showed in their research, matching the size of a canal with the tested files may influence the test results because of a different tra- jectory of a file in the canal.22, 23 In the present research, a canal of the same size and taper was used for all the files (the diameter at the end of the canal was 0.35 mm and the taper 0.06 mm/mm). This caused a small (but statis- tically significant) difference in positioning of the Endostar EP Easy Path and RACE EVO files in comparison with other files. The difference was the mean distance from the tip at which the fracture occurred. This difference was below 7%, but the level of statistical significance employed was p < 0.05, which must be considered in comparing the files. The mean length of broken fragments for files of the same type, at both curvatures, was the same, so it did not have any influence on the test. The positioning of files in the artificial canal is illustrated in Figure 6. All the tested instruments are made of NiTi alloy heat- treated in different ways. As research performed by Gambarini et al. and Zinelis et al. showed, heat-treated NiTi files are more resistant to fracture in fatigue tests.24, 25 In the present research, different types of NiTi heat treatment could not be compared because of the different design of the tested files. Glide path files, during clinical work, are also affected by significant torque (in relation to their small size). Future research should also concentrate on the resistance to torsion of these files at a temperature typical of clinical work. Conclusion Being aware of the limitations of the testing performed, it can be stated that increasing the curvature angle at which glide path files operate causes shortening of the time to fracture of all the tested files. Editorial note: A list of references is available from the publisher. about Dr Sławomir Gabry ´s graduated with a DDS from the Jagiellonian University School of Medicine in Cracow in Poland. He is a member of the Polskie Towarzystwo Endodontyczne (Polish association of endodontics) and the European Society of Endodontology and a core member of the Dental Masters Group. Since 2011, he has cooperated with the research department of Polskie Towarzystwo Endodontyczne. For eight years, with Poldent, he has conducted the postgraduate endodontic programme Endo Akademia. roots 1 2021 35

practice management | 2 Fig. 2: At the White Clinic we do not cut corners, we see fewer patients a day per chair, and since late 1999, we have not booked more than one patient per hour per chair. of hygiene and safety, thereby distinguishing themselves from their peers in their region. For that, four very simple and universally accepted cornerstones were created that could be applied in any country, under any circum- stances, and require no technology or special training. The premise was for Slow Dentistry to be able to be as ubiquitous as possible and to allow the largest number of people to join. We believe that dentists who practise according to these four simple cornerstones, taught in every school around the world, care a little bit more for themselves, their team and their patients and, as such, practise higher standards of care. They are different from those who focus simply on filling out paperwork and do- ing treatments just to make profit. A Slow Dentistry clinic usually works with less stress and is more focused on creating long-lasting relationships with its patients based on the ethical premise that goes back to the Hippocratic oath to do no harm. Often, we are so focused on the mechanics of dentistry and the major tasks that we forget the little ones, and as the famous saying goes, “the devil is in the details”. One of the most important details in dentistry is treat- ment room disinfection between appointments—proper disinfection, not simply tidying up the treatment room as happens regularly around the world. Who can claim that they have not cut corners on this important step when in a rush? Consider that apparently some dentists actually feel comfortable saying that they do not place dental dams because it takes too much time and skill, knowing full well how important it is for safety, not to mention the overall outcome and longevity of restorative dentistry and most importantly root canal therapy. When I started my private practice at the end of 1999, I had no real benchmark, and no guidelines were given to me, as I took over an old practice that had not really changed its modus operandi since the 1970s. I wanted to be modern, and I wanted to be good! So when I set up the White Clinic, I established protocols of safety and security and even the workflow that is still in place to- day. This meant that I had to do my homework and talk to the technicians who set up the treatment rooms and the sales representatives who sold me the disinfection products and have them teach me what would be the ideal way to disinfect the dental unit and used rotary instruments. I learned, quite frankly, that if you follow the guidelines it is virtually impossible to properly disinfect the treatment room, all surfaces and the floor and clear the air (open a window) after performing a treatment, whether with or without the generation of aerosols, in under 10 minutes. Therefore, when clinics are seeing in excess of 20 patients per chair a day, I always wonder what is going on with room disinfection. Or when I see dentists doing 20 or 30 restorations a day, I wonder if they are really taking the time to place dental dams. roots 1 2021 37

practice management | 5 Fig. 5: All you have to do is slow down and understand what your priorities are. They should be to work safely, ethically and responsibly. attract more patients, this is at the expense of basic safety protocols like room disinfection and placing dental dams. Portugal is not the wealthiest country in Europe; it is actually one of the poorest countries in Europe. We do not have socialised dentistry; it is almost 99% private. Practising this way for 20 years has not always been easy, but one thing is for sure: at the end of the day, our patients feel safer with us. We had many patients return to our clinic after having left us for years to go to cheaper clinics for follow-up and maintenance and, during 2020 as a consequence of the pandemic, come back to the White Clinic because they finally understood that the premium that they paid was for hygiene and safety. Moreover, when you work this way, there is undoubtably a great deal less stress at the end of the day for the clinical staff. Mental health is a major topic in dentistry today, and if you do your research you will probably find that, in some industrialised countries, suicide among dentists is one of the highest in any industry. Is it because the job is stressful? I do not think so! I believe that dentistry is actually a very rewarding job, as long as you are given time to practise it. I think many dentists go home over- worked, undervalued and stressed because they know that at the end of the day they did not do things perfectly and safely and often did not put the patient at the centre of their care. Everything we do is founded on scientific principles and clinical evidence. The basic cornerstones of Slow Dentistry are undeniably true. No dentist needs to invest in any superior education or technology to implement them. All you have to do is slow down and understand what your priorities are. They should be to work safely, ethically and responsibly. Disclaimer Slow Dentistry is part of the non profit Foundation for Excellence in Dentistry, based in Switzerland. I have no financial interest in the organisation. It was created to improve dentistry as a whole, and as part of my legacy work towards the industry. www.Slowdentistry.com Editorial note: This is the first article in a four-part series on Slow Dentistry and its principles and advantages. A list of references is available from the publisher. about Dr Miguel Stanley Rua Dr. António Loureiro Borges 5 1º Andar Arquiparque Miraflores 1495-131 Algés Portugal info@whiteclinic.pt roots 1 2021 39

feature | are determined together with the patient. In this first phase, the goals should be realistic and not too ambitious. If clinical symptoms already exist or if there are factors such as calculus or imperfect restorations that could hinder the optimal imple- mentation of dental fitness, these are professionally treated. The next step is the personalised selection of the dental fitness exercises and tools as well as the definition of the dental fitness programme through which the patient can achieve his or her personal goals. The dental fitness exer- cises and tools are physically presented to the patient and practically taught. The patient then practises first in the den- tal office under supervision until he or she has mastered the exercises and then performs them at home once or twice a day. Within two to three months, the patient is recalled in for a control appointment and, if necessary, for the correc- tion of his exercises. It is also possible to adapt or refine the recommended tools and excercises if the patient, who in fact becomes a client, is not able to reach the agreed goals. The next control and remotivation appointment takes place after another two to three months. If the outcome of this appointment is satisfactory and the patient has not devel- oped any further subclinical symptoms, it is possible to enter the lifelong monitoring phase. Depending on the indi- vidual situation, the monitoring intervals are between three and 24 months, and the next monitoring interval is individ- ually determined at each subsequent session based on the actual screening of preclinical symptoms. If preclinical symptoms are diagnosed in one of the monitoring sessions, the first approach is to try to stop the progress of these symptoms with the patient’s help by intensifying his per- sonal dental fitness efforts. A short-term monitoring interval is temporarily set for this purpose. If the measures taken have led to the arresting of the symptoms, it is possible to switch back to a longer monitoring interval. In case of symptom pro- gression, the personal dental coach will use professional non- invasive methods to try to stop it. Minimally invasive profes- sional measures are only required if the patient has not attended monitoring sessions for a lengthy period for whatever reason leading to clinical symptoms which make such procedures necessary. However, this should be the absolute exception. Implementation feasibility for dental fi tness Owing to the relatively low aggressiveness of caries and peri- odontitis progression in the vast majority of cases, a rather relaxed fitness programme is sufficient for most patients. Assuming appropriate information, instruction and motiva- tion of the patient, it is postulated that the dental fitness con- cept can be successfully communicated and applied not only to highly motivated, but also to relatively unmotivated patients. In many cases, a monitoring session scheduled every 12 to 24 months may be sufficient to prevent the ap- pearance of clinical symptoms, especially if the screening for preclinical symptoms is regularly applied so that in case of progression, these symptoms may be arrested by appropri- ate non-invasive professional therapeutic measures. Costs of dental fi tness In a patient with good compliance and a life expectancy of more than 80 years, it is estimated that lifelong dental fitness can be financed at the price of two implant-supported crowns— and this not only for a single tooth, but for the entire dentition. The role of the dentist in dental fi tness In the dental fitness context, the dentist is no longer a dental technician working on patients as is the case in traditional repair-oriented dentistry. Rather, he or she is a personal dental coach who, thanks to his or her expert knowledge and social skills, enables the patient to maintain his or her own teeth in good health for the rest of his or her life with the least investment of time and money. Advantages of dental fi tness The dental fitness concept has many advantages for patients: with a minimal investment of time and money, they can preserve their natural teeth until the end of their lives, resulting in the best possible sustainability as of today. But there are also several advantages for dentists. The concept offers the opportunity to lead a team of collaborators who can take care of the major part of the labour needed, thus taking care of a much larger number of patients than the individual dentist alone. As a result, dentists become health managers, focusing mainly on diagnostics and planning, as well as on human resources, business and opera- tional management. When working clinically on patients, they carry out relatively low-risk, micro-invasive and high-quality interven- tions. This may increase job satisfaction and attractiveness and reduce stress levels for both dental professionals and patients. Editorial note: This article was first published in Swiss Dental Journal, 2018, vol. 18, no. 1. about Prof. Ivo Krejci is professor and chairman of the Division of Cariology and Endodontology and director of the department of preventive dentistry and primary dental care at the University of Geneva in Switzerland, where he maintains an intramural private practice. He also serves as the scientifi c consultant for the school of dental hygienists in Geneva. Over the course of his career, Prof. Krejci has written over 350 articles and book chapters on topics in restorative dentistry, as well as several textbooks. Furthermore, he has supervised more than 60 doctoral theses and has lectured at numerous international scientifi c meetings and continuing education courses. He can be contacted at ivo.krejci@unige.ch. roots 1 2021 41

interview | Research suggests that staff and patient travel make up the most significant percentage of carbon dioxide emissions. Duane: Travel was central to earlier English and Scottish studies. In this study, we wanted to concentrate on the materials and processes over which we have a greater degree of control; hence we excluded travel. Borglin: In this way, we could focus on identifying other environmentally harmful processes more specific to an endodontic procedure. I have been conducting some research regarding eco-friendly dentistry, and my feeling is that sustain- ability is not a top priority for the average dental pro- fessional. Do you agree with this conclusion? And if so, what do you think are the main reasons that hold dentists back from reducing their carbon footprint? Duane: Many dentists are trying to survive financially and juggling all the additional protections needed for patients so when you mention sustainability, you can get blank looks. I think it wasn’t a priority at all say 5 years ago, but there is a growing number of dentists, especially in the younger generation which realise the importance and relevance of this area of dentistry. There are so many barriers to dentists being involved in sustainability and there are few facilitators. We need a comprehensive programme of education, an incentivisation programme; basically, sustainability needs to be normalised and embedded in everything we do. jurisdictions are considered to be of single use only, the drive towards more sustainable endodontics should firstly be aimed at reducing the number of patient visits. Single visit treatment will reduce factors such as the number of files, sterilisation costs, and patient and operator time. A second way to improve sustainability would be to limit exposure and to consider vital pulp treatment for cases exhibiting symptoms of pulpitis. “Single visit treatment will reduce factors such as the number of fi les, sterilisation costs, and patient and operator time.” The employment of minimally invasive techniques where possible reduces treatment times, cost and instrument use and, in doing so, the environmental burden. Finally, if local rules allow, and if compliance with cross-infection regulations can be ensured, instru- ments should be reused. Do you have any tips for the endodontic team on how they can reduce the environmental burden of endodontic care? Duncan: As modern root canal therapy uses a large number of instruments such as files, which in many Editorial note: The study, titled “Environmental sustain- ability in endodontics. A life cycle assessment (LCA) of a root canal treatment procedure”, was published on 1 December 2020 in BMC Oral Health. According to researchers, editors of journals need to be cognisant of sustainability in dentistry as a developing area and facilitate the publication of high-quality research. m o c . k c o t s r e t t u h S / 7 a l roots 1 2021 43

m o c . k c o t s r e t t u h S / u e . e e h p a r g o t o h P appropriate measures in education to ensure future dental professionals have reached the General Dental Council’s standard of clinical competence and can enter the work- force with confidence,” she noted. To help avoid crippling debt for students, the Scottish government will be offering financial support to those who have been asked to repeat their final year. According to Gougeon, affected students will be eligible for a bursary equal to the amount of their student loan. Dental schools in Europe are yet to make the decision Discussing the situation in Europe, a spokesperson at the European Dental Students’ Association (EDSA) told DTI: “We know that a lot of students are particularly worried about their lack of experience and the impact it will have on their future education and job prospects. Every student has the right to build a successful career and to receive dental train- ing that prepares him or her to deliver safe and effective oral health care to the population he or she serves. If a student has received insufficient clinical experience to provide this, then a limited extension to the length of his or her course may be appropriate, depending on the local context.” According to some sources, several universities in Malta and Greece have already chosen to extend their terms. Other countries are considering taking the same action but have not yet made the final decision. Talking about possible extensions to the length of courses, the association noted that any extensions granted to stu- news | dents should be proportional to the amount of clinical time missed. However, EDSA noted that dental schools should consider carefully all the options available to safely increase the provision of clinical teaching and to avoid extensions where possible, since these may lead to financial burden. The spokesperson added: “Students must be protected from the financial impact of extending their studies. They should not pay additional fees, and schools and govern- ments should seek to provide financial support for living costs, especially for those who may struggle in the case of an extension.” Dental schools in the US still accepting students Although the COVID-19 pandemic has severely disrupted dental education in Scotland, the situation is not the same in some other parts of the world. For example, for dental schools in the US, it is business as usual. Dr Karen P. West, president and CEO of the American Dental Education Association, told DTI: “Dental education continues to move forward in the US, and all existing dental schools in the country are continuing to accept new students this year. In fact, applications to schools are thriving.” Students in the country have been quick to adapt to the changes in teaching and learning and have embraced the shift to virtual classrooms, with all its possibilities. “Although the COVID-19 pandemic disrupted learning last year, schools adapted and developed innovative educa- tional environments in which to teach and learn. In accor- dance with the Centers for Disease Control and Prevention guidelines for patient care in the COVID-19 environment, students are providing clinical care, and competency assessments are continuing,” she noted. “Although the COVID-19 pandemic disrupted learning last year, schools adapted and developed innovative educational environments in which to teach and learn.” “Students are not being asked to repeat the 2020–2021 academic year based on COVID-19 alone. To their credit, faculty and students quickly adjusted to the changed environment, embracing virtual learning options that have allowed dental education to grow and flourish in new and ground-breaking ways,” West concluded. roots 1 2021 45

Removers leave a lasting impression Single-file retreatment system for endodontic treatment proves convincing for dentists in practice test After the market launch of its new retreatment files last year, Swiss dental specialist COLTENE recently launched a test initiative among dentists and endodontic specialists, followed up by a survey on their experience with the Remover for the HyFlex and Micro Mega file systems (Fig. 1). The verdict of first-time users is conclusive: in particular, switching in a retreatment from various hand files to a single nickel–titanium (NiTi) file provides significant benefits in dental practice. The removal of insufficient endodontic restorations has become a standard treatment in practices owing to an increase in retreatment. The new Removers employ the latest technologies, such as asymmetrical design, electropolishing and thermal treat- ment, to make treatment safe, easy and fast. A look at the responses from the clinicians surveyed shows that the benefits were clearly seen in practice: “The new Remover makes gutta-percha removal very easy and fast”, “Perfect harmony between efficient removal and sensitive tactile feedback”, “Respects complex root canal anatomies” and “Makes my endodontic life more convenient” were among the dentists’ comments. One endodontic expert con- cluded as follows: “A single instrument for removing old gutta- percha, the HyFlex Remover fulfils the dream of many dentists.” Fast, reliable, intuitive—participants in test confirm excellent efficacy and faster treatment As part of a Europe-wide test initiative, individual and group dental practices were given the opportunity to try out the Remover exten- sively over the past few months. The initial survey results con- firmed that more than 80% of the participants regarded the file as demonstrating excellent or good efficiency at removing insufficient obturation material. Almost half of the respondents were thus able to perform their work significantly faster than before. The 30/.07 Remover is optimally designed for the situation of a previously prepared canal and, owing to its intricate shape, adapts to the natural contour of the canal to efficiently loosen the existing dental material. The file removes gutta-percha mechanically from the root canal, thereby eliminating the need for an additional solvent Fig. 1: Online survey results for the Remover files. which may be toxic for the patient. At the same time, the sur- rounding tooth structure benefits from the intelligent file design: a non-cutting tip provides additional safety during preparation. Handling is extremely simple and intuitive, as was confirmed by more than 80% of the respondents. More than three-quarters were in- stantly so convinced of the advantages that they said that would not wish to do without the new file in their practices in the future. The Remover file is available in 19 and 23 mm lengths (Fig. 2). A large number of cases can be treated with the 19 mm file. The last millimetres can then be cleaned with the matching HyFlex EDM and CM or MicroMega 2Shape and One Curve files to give an optimum result. The Remover file is fully integrated into these file systems, which are then also used to perform the subsequent finishing of the missing root canal cleaning. Integration into the dental practice COLTENE will again offer a series of training courses, practical work- shops and webinars in 2021 on the optimal integration of the new files into COLTENE’s NiTi systems as well as on various application issues in endodontics. On www.coltene.com or one of the innovation leader’s social media channels, interested dentists can currently find out about the latest trends and ideas from the dental world in the comfort of their own homes. This way, even endodontic beginners will be able to achieve competent and efficient preparation after only a short time. www.coltene.com Fig. 2: Remover for HyFlex and MicroMega file systems. roots 1 2021 47

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