N L Y A L S O N F E S SI O O R T A L P N E D PUBLISHED IN DUBAI www.dental-tribune.me January-February 2021 | No. 1, Vol. 11 Innovative endodontics using SWEEPS technology: Tips and tricks By Drs Giovanni Olivi, Linhlan Nguy- en, Matteo Olivi & Jason Pang, Italy & Australia Conventional endodontic treatment is based on different phases, result- ing in the elimination of acute or chronic inflammation of the pulp and periapical area (Table 1).1–3 The different phases of the therapy are: • initial cleansing of the endo- dontic space, shaping the root canals to a size sufficient for delivery of ir- rigants, final cleansing and 3D disinfec- tion of the endodontic space, and 3D sealing of the endodontic space and restoration of the post-endodontic space and the crown to conclude the therapy. • • • The cleansing and shaping phases include two different types of cleans- ing: a chemical cleansing, carried out by different irrigating solutions, and a mechanical cleansing, car- ried out by endodontic instruments that shape the root canals. However, many studies have demonstrated the incomplete action of the tested instrumentation, which left 35% or more of the canal surface area un- changed.4–6 Accordingly, it is the ef- ficient irrigation of the endodontic space that determines the success of the therapy. During the shaping phase, hand irrigation is performed using a syringe with an end- or side- vented needle, alternating with in- strumentation using files of different sizes. Besides reducing the bacterial load, irrigants act as a lubricant dur- ing filing prior to the final activated irrigation protocol. The purpose of this article is to present an innova- tive rationale for endodontic thera- py using the newest cutting-edge la- ser technology SWEEPS (shock wave enhanced emission photoacoustic streaming). Not previously treated Previously treated Asymptomatic irreversible pulpitis Symptomatic irreversible pulpitis Asymptomatic apical periodontitis Asymptomatic apical periodontitis Symptomatic apical periodontitis Symptomatic apical periodontitis Table 1: Diagnostic classiﬁcation of endodontic pathology.1–3 Irrigating solutions in endodontics In endodontics, different irrigating solutions are used to kill microor- ganisms, dissolve the organic com- ponents (pulp remnants and col- lagen), and chelate and remove the inorganic components (calcification and debris).7 The smear layer is com- posed of both organic and inorganic components. However, there is no ir- rigating solution that has all the ideal characteristics.7 An effective irriga- tion approach is based on a specific alternating sequence of use of differ- ent irrigating solutions, before, dur- ing and at the end of the therapy. Af- ter creation of an access cavity, root canal therapy is started by cleaning the pulp chamber and canals using an irrigant with antibacterial and pulp-dissolving action. Sodium hypochlorite Sodium hypochlorite (NaOCl, 1–6%) is the main irrigant used in endo- dontics owing to its high bactericidal activity and pulp tissue dissolution action.7 Higher NaOCl concentra- tions achieve faster bacterial load reduction; however, the more con- centrated the solution of NaOCl, the thicker it is, resulting in reduced wet- ting ability. NaOCl is still recognised today as the gold standard solution in endodontics because of its use from the initial to final phases of the therapy.7 NaOCl has significant biological toxicity risk for periapical tissue when pushed under pressure through the root canal orifice.8 The outcome is significantly worse for higher concentrations. EDTA Irrigation with chelating solutions such as ethylenediaminetetraacetic acid (EDTA, 15–17%) is often utilised during root canal therapy. When al- ternated with NaOCl, such as in cases of calcified canals and at the end of ÿPage A2 AD RECIPROCATION RECIPROCATION RECIPROCATION REDEFINED REDEFINED REDEFINED THE THE ACE RACE LEGACY LEGACY SAFE. EFFICIENT. SOFT CONTROL. SAFE. EASY. MINIMALLY INVASIVE. www.fkg.ch/race-evo www.fkg.ch/r-motion
A2 ◊Page A1 ENDO TRIBUNE Dental Tribune Middle East & Africa Edition | 1/2021 Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 1: Tooth #12—the radiograph showed a large periapical lesion. The asymptomatic tooth was prepared with an ISO 25/.06 TF Adaptive ﬁle (Kerr Dental). Fig. 2: Tooth #12—root canal ﬁlling was performed with mineral trioxide aggregate (ENDOSEAL MTA, Maruchi). Note the sealing of the apical ramiﬁcation, possible because of the effective cleansing and decontamination of the apical terminus. There was almost complete healing after 12 months. Fig. 3: Tooth #33— the patient showed a buccal sinus tract that radiographically corresponded to the area between tooth #32 and tooth #33. The CBCT and radiograph showed a large periradicular lesion, especially on the distal side. Preparation was performed with a 20/.07v ProTaper Gold (F1; Dentsply Sirona). Fig. 4: Tooth #33—root canal obturation was performed with a sealer and carrier-based gutta-percha (AH Plus and Thermaﬁl, Dentsply Sirona). The radiographic control six months post-op showed that several lateral canals had been ﬁlled and the healing process was in progress. at 50°C, which left a higher quantity of debris and the smear layer widely distributed.14 Other studies have reported that NaOCl at a concentra- tion of 1 % heated to 60°C was signifi- cantly more effective than 5.25% at 20°C. The advantage of using lower concentrations of NaOCl, heated to higher temperatures, could be re- lated to a twofold effect: the same effectiveness and less systemic tox- icity than that of non-heated, high- concentration NaOCl.15 Agitation techniques However, the effect of agitation on tissue dissolution was proved great- er than that of temperature and with continuous agitation resulted in the fastest tissue dissolution.16 Compar- ing the efficacy of various agitation systems, De Gregorio et al. found a limited penetration of the irrigant into lateral canals using an apical negative pressure irrigation system, whereas passive ultrasonic irrigation demonstrated significantly more penetration of irrigant into lateral canals.17 Nevertheless, it could be reasonable to combine the two tech- niques, using heated NaOCl and agi- tating it with the preferred method. Laser-activated irrigation using SWEEPS The physical concepts behind laser- activated irrigation and SWEEPS technology have already been ex- plained in a previous issue of this magazine (roots-international maga- zine of endodontics 4/2019).18 One of the great advantages of SWEEPS over all of the other activation techniques is its profound effectiveness. Unlike all the other techniques, SWEEPS ac- tion is not limited to the vicinity of the tip, as is the case with ultrasonic irrigation, but it is also effective at distant regions of the root canal sys- tem.19,20 For this reason, SWEEPS only requires positioning of the tip in the access cavity to stream the irrigant into all of the endodontic space at the same time. This is different to other techniques, which require nee- dle or tip/ file or probe insertion up to the apical third of each canal or so for irrigation after the root canals have been prepared. Thus, SWEEPS Fig. 5: Proper isolation for SWEEPS is important. A liquid dam was interlocked beneath the dam clamp. Traditional access cavity preparation of the maxillary ﬁrst molar was performed using a cylindrical or round diamond bur under magniﬁcation (4.5–6.0 x). the treatment, EDTA cleans the canal walls of debris and the smear layer produced during instrumentation, just before the final decontamina- tion. EDTA is slightly irritating but not toxic to periapical tissue. Chlorhexidine Chlorhexidine (2%) has good an- tibacterial properties, but it is not able to dissolve pulp tissue. This sug- gests its use only in an additional final decontamination step because of its unique substantivity prop- erty, which could allow persistent residual antimicrobial action. It is important to prevent interaction between NaOCl and chlorhexidine, by rinsing the canals with distilled water in between solutions to avoid the formation of precipitates that may discolour the tooth and that may contain potentially mutagenic compounds.9,10 Its inability to dis- solve organic tissue also explains the absence of toxicity to periapical tissue.11,12 Other solutions Other chemical solutions have been investigated and used in endodon- tics. Among these, hydrogen per- oxide, iodine, citric acid, ozone (gas) and ozonated water are available, but none of them have demonstrat- ed superior properties and results to the previously cited NaOCl and EDTA solutions. EDTA plus Cetav- lon and a mixture of doxycycline, citric acid and a detergent are new solutions that combine different components, surface-active agents and antibiotics which can be very ef- fective and have broader action. The experimental use of nanoparticles is also very promising. Irrigant activation techniques The initial irrigation phase and the irrigation during shaping are per- formed using a syringe with an end- or side-vented needle that can only negotiate the canal up to the middle third. Therefore, it must be considered that the efficacy of hand irrigation is quite limited; thus, sup- plementary, active and dynamic ir- rigation (Table 2) is proposed at the end of the treatment to ensure the cleaning of the dentinal walls and the deep decontamination of the en- dodontic system.13 Among the vari- ous activation methods, we can find systems that heat the irrigating solu- tions or that activate the solutions by agitation, with positive or negative apical pressure. Heating Scanning electron microscope stud- ies on intra-canal heating of NaOCl at 180°C have proved this method to be more effective for cleaning the canal walls than extra-canal heating Chemomechanical systems Positive pressure systems Negative pressure systems XP-endo Finisher Hand dynamic Sonic Multi-sonic Ultrasonic Laser-activated irrigation (PIPS* and SWEEPS**) XP-endo Finisher * PIPS = photon-induced photoacoustic streaming. ** SWEEPS = shock wave enhanced emission photoacoustic streaming. Table 2: Irrigant agitation techniques. can be used from the initial phase up to the final phase of the therapy, permitting a progressive decrease in the bacterial load before any le is used. The efficacy and effectiveness of SWEEPS rely on both chemical activation of the endodontic solu- tions by agitation,21,22 improving the ability of irrigants to kill bacteria and to dissolve tissue, and mechani- cal flushing action to clean the root canal wall.23,24 Researchers have found the SWEEPS dual modality to be more effective than the single-pulse modality SSP (super-short pulse; PIPS, photon- induced photoacoustic tic stream- ing).25–28 Using the SWEEPS dual-pulse modality, the sudden expansion of the second bubble, generated by the second laser pulse, exerts additional pressure on the first bubble, lead- ing to its violent collapse, during which shock waves are emitted also in very small canals. Furthermore, shock waves are emitted from the collapsing secondary cavitation bub- bles that form naturally throughout the entire length of the canal during irrigation.25–29 The laser-activated secondary cavitation bubbles are in close proximity to the canal walls during their collapse, generating shear stress and vortical flows that are able to remove debris, the smear layer and biofilm from the root canal surface, as well as from undetected and uninstrumented anatomical ar- eas, such as isthmuses, lateral canals, loops and ramifications, thereby in- creasing the cleaning and decontam- ination mechanism even further (Figs. 1–4). The enhanced pressure generation along the root canal con- sequently also increases the depth of penetration of irrigants into dentinal tubules.25–28 Clinical protocols Proper patient draping with a water- proof bib to protect clothing is high- ly recommended. Local anaesthesia is performed in all cases (asympto- matic and symptomatic) to avoid any unpleasant sensation of internal pressure during the treatment. A dental dam is then applied, and a liq- uid dam is interlocked beneath the clamp to ensure complete isolation (Fig. 5). In case of occlusal or proximal decay or a defective filling, complete removal of the carious tissue and filling must be performed, followed by composite reconstruction of the entire tooth crown; this preliminary step is mandatory to minimise leak- age and reinfection. Furthermore, good marginal sealing prevents any irrigant extrusion during laser-acti- vated irrigation. Access cavity preparation At this point, the access cavity is opened using a small carbide, or cylindrical or round diamond bur under magnification (4.5–6.0x). Traditional access cavity prepara- tion, following the laws of central- ity and concentricity, is advisable (Fig. 5).30 Several studies have dem- onstrated the lack of usefulness of ultra-conservative “ninja” access cav- ity preparation in terms of fracture strength and preservation of the original canal anatomy during shap- ing compared with traditional access cavity preparation, particularly at the apical level. Furthermore, stand- ardised access cavity preparation is advisable when the X-SWEEPS mo- dality is chosen for laser-activated irrigation. Future publications will explain this topic in depth in order to establish the correct laser settings to be used with standardised access cavity preparation volumes. What- ever the pathology is, the concept is to minimise the root canal shaping, optimising the cleansing and decon- tamination of the endodontic space by exploiting the chemomechani- cal flushing of SWEEPS. The main difference between asymptomatic and symptomatic pulpitis and apical periodontitis therapy is in the longer or shorter initial NaOCl SWEEPS-acti- vated irrigation phase. Retreatment also involves a few differences in the energy applied during the initial phase when filling material has to be removed. Asymptomatic and symptomatic irreversible pulpitis In the case of irreversible pulpitis, the pulp is irreversibly inflamed, with or without acute symptoms. The patient’s age and preoperative radiograph give information on a possible immature apex; this con- dition contra-indicates a full-power SWEEPS irrigation and suggests a more careful intervention and low- ering of the energy used (more to follow). Once the pulp chamber has been opened, excessive bleeding may be present, indicating the pres- ence of inflamed pulp tissue inside the chamber and root canals. In this case, one-visit therapy is advisable. The treatment starts with NaOCl irri- gation by syringe (3–5 ml) and simul- taneous activation by Er:YAG laser (2,940 nm; LightWalker AT, Fotona), using the dual-pulse (25 µs duration) Auto-SWEEPS modality for 30–40 seconds. The resting time after irriga- tion can be extended to 1–2 minutes to allow more NaOCl pulp dissolu- tion. A at- or radial-ended SWEEPS tip (400 µ) is used. The pulp tissue may show different grades (levels) of inflammation, up to initial necrotic degeneration. It is important to con- sider at this stage whether the pulp tissue itself is preventing any extru- sion of the irrigant so that full-power Auto-SWEEPS activation (20 mJ at 15 Hz and 0.6 W) can be performed up to almost complete pulp dissolu- tion, which is indicated by a progres- sive decrease in bleeding. According to the tooth type and condition, this initial phase can be repeated for two to three cycles for single-rooted teeth and up to three or four cycles for pre- molars and molars. The initial irrigation phase also de- creases the bacterial load. The access cavity can now be observed under magnification (6–10x) in order to locate all canal orifices. If the orifices are not all visible, the use of ultra- sonic tips can easily discover orifices hidden under calcification in the pulp chamber. These are usually lo- cated at the angles, at the floor–wall junction and at the terminus of the root developmental fusion lines. Then pre-flaring of the orifices and enlarging of the coronal thirds of the canals allow easy and direct access to the canals. Subsequently, a direct glide path to the apical third is estab- lished by hand or dedicated rotary ÿPage A3
Dental Tribune Middle East & Africa Edition | 1/2021 ENDO TRIBUNE A3 ◊Page A2 instruments, up to 3–4 mm from the apex. This manual or rotary instru- ment step produces debris and den- tine chips that must be removed by AutoSWEEPS NaOCl irrigation, again for 30–40 seconds, followed by 30 seconds of resting time. At this point, use of a small stainless-steel hand le (ISO 06 to 10) is recommended with a cream containing urea peroxide or EDTA to lubricate and avoid tis- sue plugging when sliding the le to the anatomical opening to scout the canal and determine the anatomical length (Fig. 6). It must be emphasised that by now most of the pulp tissue will have already been dissolved by NaOCl and the possibility of dislodg- ing pulp remnants or debris inside unreachable anatomical areas is very difficult if the previous phases have been correctly followed. Also, the bacterial load is highly decreased so that apical transportation of bacteria is minimal or absent. Use of an elec- tronic apex locator and radiographic confirmation provide verification of the anatomical length of the tooth. Different approaches to the apical constriction can be used: working to the anatomical length or 1 mm shorter, in order to prevent possible over-instrumentation of the apex with enlarging of the apical opening. This is one reason for possible extru- sion at the end of treatment (Fig. 7). At this point, the canals can be mini- mally prepared. Because SWEEPS technology does not require the tip to be placed in the canal, it is not nec- essary to prepare the canals to a large size. This results in a more conserva- tive and biomimetic result: 20/.06 and 25/.06 are sufficient to warrant a hermetic apical obturation. These two or three mechanical preparation steps are always alternated with Au- to-SWEEPS NaOCl irrigation and re- capitulation with the smaller first in- strument (ISO 06 or 08) used at the apical anatomical constriction to en- sure apical patency and remove any possible dentinal plugs produced during instrumentation (Fig. 8). Asymptomatic and symptomatic apical periodontitis Chronic pathology can last for years without symptoms and without temperature hypersensitivity, and diagnosis can be done occasionally during check-ups with radiographic control. It ranges from minimal lami- na dura dilatation to larger periapical radiolucent lesions. If symptomatic, the tooth presents with a painful dull ache, intermittent pain, gingivae that can be sore to the touch, up to excruciating pain in cases of are-ups, possible buccal swelling and a possi- ble visible buccal sinus tract, and the tooth is tender to percussion. More frequently, such a tooth has under- gone previous dental treatments, such as a full-crown or deep restora- tion with or without recurrent caries, and may have untreated deep decay (cavity) extending to the pulp cham- ber. In this case, carious removal and cavity filling reconstruction are pre- liminarily performed as previously mentioned. When creating the access cavity, the chamber and the canals are usually empty, with no pulp tissue. Some- times, especially in molars, the pulp condition can differ from one canal to another. Some may present with minimal bleeding. In case of swell- ing and a periapical abscess, pus may ow out of the tooth from the open- ing into the canal orices. Treatment starts with two to three cycles of saline irrigation (3–5 ml by syringe) and simultaneous activation by Er:YAG laser (2,940 nm; LightWalker AT), using the dual-pulse (25 µs du- ration) Auto-SWEEPS modality for 30–40 seconds, at 20 mJ and 15 Hz. This preliminary irrigation with sa- line, besides its initial cleansing and Fig. 6: After the cavity access has been prepared, laser-activated irrigation of NaOCl using SWEEPS is performed in the access cavity. Then lubricant gel containing urea peroxide is placed on the le (or in the cavity) to lubricate and avoid tissue plugging when sliding the le to the apical constriction. (Courtesy of Dr Giovanni Olivi) Fig. 7: In order to prevent possible over-instrumentation of the apex with enlarging of the apical opening, the authors suggest working to 1 mm shorter than the anatomical length. antibacterial action,33 helps to test the patency of the apical constriction to the pressure applied. Frequently, chronic periapical inflammation can lead to an enlargement of the apical constriction so that irrigant extru- sion can occur, especially in cases of apical contraction larger than ISO 40–50. Then NaOCl irrigation is ac- tivated by Auto-SWEEPS, using a low energy, 10 mJ, at 15 Hz for 30 seconds to start the decontamination and lubrication of the canals prior to us- ing the ISO 10 hand le to explore the canal and verify patency and ana- tomical length. Once apical patency and working length are established, new NaOCl irrigation activated by Auto-SWEEPS is performed. The pos- sibility of decreasing the energy out- put from 20 mJ to 15 or 10 mJ allows reduction of the streaming pressure to the apex. However, the dual-pulse Auto-SWEEPS modality promoted an almost constant flow rate for differ- ent pulse energies of between 10 mJ and 20 mJ, compared with the single- pulse modality SSP, indicating supe- rior safety of Auto-SWEEPS regardless of the pulse energy.29 Furthermore, the pressure efficacy is higher for a smaller fibre tip diameter (400 vs 600 µ), and radial-ended fibre tips are slightly less effective for gen- erating pressure in comparison with cylindrical tips.28 To simplify, in case of a larger apical size, it is suggested to use the Auto-SWEEPS modality with a larger size tip (600 µ), preferably with the radial-ended tip (X-Pulse). This management of energy and tip choice allow beginner users to work carefully in case of altered apical anatomies. When the apical opening is more than ISO 40–50, a simple operation that permits control of any unwanted irrigant extrusion is the use of a par- ticularly smooth needle le of different calibres (from ISO 40 to ISO 100). The apical end closes the apical opening of the canal while laterally all the irrigant flows throughout the canal. Calcified canals Sometimes canal restrictions and calcifications, due to tertiary dentine formation, may be found, hindering the negotiation of the canal (Figs. 9 & 10). In case of a multirooted tooth, another canal may be accessible and the usual protocol can be applied up to completion of root canal filling (Figs. 11–13). In a separate session, the calcified canal is irrigated by EDTA solution, activated and forced by full- power Auto-SWEEPS, at 40 mJ and 15 Hz (Figs. 14 & 15). The single-pulse USP mode (25 µs) can also be more ef- fective for pressure generation. Note that, if the canal is obstructed by calcification while the other canals have already been prepared with files, this procedure at higher energy is very safe. EDTA in this case is used to chelate and soften the dentine, but sometimes the use of a thin, rigid ul- trasonic tip is necessary to remove the calcification in the coronal third. Stainless-steel hand files with EDTA gel can be used to help bypass the blockage in the middle and apical thirds. Final irrigation protocol At the end of the preparation and before the final irrigation protocol, the root canal system has already been cleansed and disinfected by the SWEEPS protocol used from the beginning of the therapy. Further research is required to confirm the reported efficacy and effectiveness of SWEEPS’s cleansing ability and pressure generation regarding de- contamination. Several researchers have reported the superior decon- tamination results of the SSP mo- dality using PIPS.34–36 Therefore, this ÿPage A4 Fig. 8: Recapitulation with the smaller ﬁrst instrument (ISO 06 or 08) is performed to the apical anatomical constriction (working length + 1 mm) to ensure apical patency and re- move any possible dentinal plugs produced during instrumentation. The last millimetre is just cleansed and disinfected by SWEEPS. (Courtesy of Dr Giovanni Olivi) Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 9: The symptomatic maxillary second premolar showed a periapical lesion on radiographic examination. The preparation of the buccal and palatal canals was performed with a 25/.08v ProTaper Gold (F2) to 4 mm short of the radiographic apex. A size 10 hand instrument was used up to 2 mm short of the apex. Fig. 10: The calciﬁed canals hindered the negotiation of the apical constriction. Full-power Auto-SWEEPS (40 mJ, 15 Hz) activation of 15 % EDTA solution was able to force through the blockage to cleanse and disin- fect the last 2 mm of the conﬂuent curved canals. Obturation was performed with Thermal and AH Plus sealer. Fig. 11: A symptomatic maxillary ﬁrst molar with large mesioocclusal decay and a large periapical lesion. Fig. 12: Root canal preparation was performed with a 25/.06 ProTaper Next X2 (Dentsply Sirona) in the buccal canals and 40/.06 X4 in the palatal canal, which demonstrated pre- existing apical resorption. Obturation was performed with EndoSequence BC Sealer (Brasseler) and gutta-percha. The ﬁrst and second me- siobuccal canals merged into one unique larger canal in the apical third. Fig. 13: The three-month post-op radiographic examination showed that healing was progressing rapidly. Fig. 14: Radiograph showing deep distal caries with a large periapical lesion on sympto- matic tooth #47. The mandibular molar presented with a typical C-shaped canal, and it was prepared with an ISO 25/.06 TF Adaptive le. Fig. 15: Auto-SWEEPS (20 mJ, 15 Hz) activation of 4 % NaOCl and 15 % EDTA solution was able to dissolve the tissue and debris from the complex radicular anatomy, allowing a sealer (EndoREZ, Ultradent) to ll the full endodontic space (ve-month post-op radiograph).