EdgeFile ® X7 rotary files and IrriFlex ®

Dr. Zak James discusses how to achieve complete healing with minimally invasive cleaning and shaping

”Anyone can build a bridge that stands. But it takes an engineer to build a bridge that barely stands.”Orso an engineer once told me. But is this also true of endodontics? As we advance non-surgical endodontic therapy into the 21st century,the etiology and problem of pulpitis and apical periodontitis remains unchanged—bacterial biofilm introduced into complex, three-dimensional root canal systems. Historically, successful removal of this biofilm required aggressive instrumentation in order to facilitate successful disinfection, but cleaning and shaping has rapidly evolved with changes in material science. We now have the instruments to perform root canals that minimally excavate, yet completely heal—building bridges that barely stand.

We have long known that bacteria and other microorganisms are required to induce pulpal and apical disease.^1,2 It has since been understood that to restore health and function requires successful removal of the offending bacteria.³ Scores of researchers, clinicians, and engineers have sought to produce the most efficient files, irrigants, and adjuncts in order to eliminate biofilm from complex root canal systems. Historically, this required large coronal preparations in order to achieve“straight-line”access to root canal orifices, so that relatively rigid Gates Glidden,stainless steel, and NiTi files might successfully negotiate canal systems to the apical terminus with minimal risk of iatrogenic error. These preparations were generally of a larger taper, in order to facilitate sufficient syringe placement for adequate fluid exchange in the apical third. But with time, it became evident that excessive removal of coronal and peri-cervical tooth structure could weaken teeth, facilitating irreparable fracture—leading to extraction.⁴ With the advent of contemporary heat-treated NiTi instruments, that problem has been greatly mitigated. However, the question has thus become—how conservative is tooconservative for adequate cleaning?

Instrumentation of the root canal system serves primarily to facilitate space for adequate fluid exchange fordis infection and disruption of established biofilm. Mechanical instrumentation is sufficient to render canals partially clean,^5,6 but only with proper irrigation can canals be thoroughly disinfected to allow for sufficient healing. Historical evidence has demonstrated that coronal flaring followed by large apical preparations have been required to render canals sufficiently bacteria-free.⁷ Preparation sizes of 40.04,^7,8 or at minimum, a master apical file (MAF) of three sizes greater than the first binding file9 were considered necessary to ensure a clean apical constriction. Largely this was due to the limitations of irrigation, which required sufficient canal preparation in order to insert a rigid 27-30g irrigation tip, such asa Max-i-Probe®,¹⁰ within 1 mm to 2 mm of the apex.¹¹

Many file systems have been marketed as an attempt to be the ultimate endodontic instrumentation solution.Realistically,all files present with a series of trade-offs. More aggressive cutting generally comes with greater risk of separation or less shape memory,while better heat treatment and flexibility tend to reduce cutting efficiency. More aggressive coronal flare facilitates better access for irrigation, but at the expense of tooth structure. Therefore, what is needed is both an instrumentation and irrigation combination that complement the strengths of each step into a synergistic system. EdgeFile®X7 rotary files with IrriFlex®provides such a sequence.

I have been using the EdgeFile X7 file system since the beginning of my endodontic residency and still use the files almost exclusively in private practice. The proprietary FireWire™ NiTi technology is superior to any metallurgy I have tried. The files are extremely flexible and have superior shape memory, so that they can be pre-bent into almost any orifice—no matter how conservative the access or limited the opening. Second molars, which would traditionally have required very large accesses for other systems, are routinely accessed with X7. While 21 mm length is readily available, I find that 25 mm length files are easily pre-bent into the most limited of openings. Both 0.04 or 0.06 straight taper files exist, and can be combined in series if desired. The files do not cut aggressively and require frequent cleaning of the flutes. When used with appropriate technique, the files will nearly always unwind in tortuous anatomy rather than separate, and so I have high confidence using them in the most calcified or curved canals. In canals where even small hand files fail to negotiate, X7 finds a way. However, given their straight taper and cutting flute design only to D12, even larger apical preparations may be difficult to facilitate traditional irrigation tips to the apical third without binding in the coronal ormid-third. Enter IrriFlex.

Any dentist who has attempted endodontic retreatment has noticed the difficulty in completely removing previous obturation material. Whether gutta percha, sealer, or calcium hydroxide, it becomes abundantly clear that files alone are insufficient to adequately clean the root canal system, as invariably some debris remains in hard to reach undercuts,isthmuses, and anatomy that files simply cannot negotiate. Literature shows that no traditional rotary or reciprocating filesystem touches all the walls in three dimensions.¹² And if our files cannot remove all the previously obturated material, itstands to reason they certainly cannot mechanically disrupt or remove all bacterial biofilm. Mechanical debridement can only render most canals about 60%-70% clean, requiring disinfecting and chelating irrigants to disrupt the remaining biofilm and eclipse the threshold of disease for healing to occur.¹³

Most classic literature cites the use of a 30-gauge Max-i-Probe or equivalent syringe tip as the best choice for irrigation of traditionally shaped preparations. Tips should be placed short of the working length with a side-vent in order to prevent apical binding. But for most of us, placing a 30-gauge Max-i-Probe to length can be a challenge. And if the tip will go to length, fluid exchange can feel painfully slow, or even clog, leading to fatigue and frustration. IrriFlex tips do not suffer these limitations. Designed from polypropylene with double side vents, the“needle”easily adapts to the most complex canal morphologies and curvatures. In canals where a traditional probe will bind coronally, the IrriFlex will passively seatto working length without engaging dentin. The needle can be slightly pre-bent, allowing for ease of use in limited space or opening. With a 0.04 taper, it readily fits X7 preparations and comes with pre measured markings to assist in gauging depth of placement. The 25 mm length can easily adapt to short or long canals, and the passive dual side-vent design allows for easy, efficient, and controlled fluid release from the apical third, flushing debris coronally. The polypropylene is compatible with full strength or diluted NaOCl, 17% EDTA, chlorhexidine, or saline rinses. Irrigation with the IrriFlex is far simpler, safer, and efficient in my hands versus any probe I have used in the past, regardless of gauge. For X7, it is a perfect pairing.

We now have the tools to efficiently and conservatively build endodontic bridges that are stable and functional,without the need for prohibitively expensive engineering or untested adjunctive technologies. The evidence is abundantly clear that evidence-based NiTi instrumentation with proper irrigation will yield success, as it has always done. For both general dentists and endodontists alike, EdgeFile X7 with IrriFlex is a safe, efficient, and predictable cleaning and shaping solution for minimally invasive endodontics. To request a product sample of the EdgeFile X7 for evaluation, please visit:https://edgeendo.com/product-evaluation/. Kindly note that IrriFlex is not yet available for evaluation.