IRRIGATION IN ENDO

[drmithila]

If instrumentation were 100% effective in removing all bacteria and debris from the canal, irrigation would be an insignificant adjunct to mechanical debridement. We would irrigate only to lubricate and facilitate canal instrumentation. Unfortunately, this is not the case. There are many studies that show the limited ability of instrumentation alone to debride and clean the canal.1-5 Wu and Wesselink6 reported uninstrumented areas in 65% of instrumented oval canals. Rödig et al7 studied nickel-titanium (Ni-Ti) rotary instrumentation of buccal and lingual extensions of oval canals and found inadequate controlled debridement.
The complete shaping and debridement of root canals is often very difficult because of the morphology of the canals. Many canals are oval in shape with outpocketing, evaginations and undercuts containing tissue. Peters et al,8,9 studying the effect of 5 Ni-Ti rotary instrumentation systems, found that all techniques left 35% or more of the canal unchanged. Using ProTaper, GT rotary, Light Speed, and Profile, approximately 35% to 40% of the root canal surface was not prepared, and no significant differences between the systems were noted when studied and reported by Vaudt et al.10 Sherman and Sultan11 compared smear layer removal after instrumentation and irrigation using SafeSiders reciprocal system, ProTaper, Mtwo, and HeroShaper rotary Ni-Ti instrumentation systems. All systems removed the smear layer in the coronal third. SafeSiders, a reciprocal system, demonstrated far better smear layer removal in the middle and apical thirds than did any of the 3 other rotary systems.11
It seems from the literature that most rotary instrumentation systems do an adequate job in shaping the canal but a poor job when it comes to debridement and cleaning of the canal. No instrumentation technique comes close to sterilization of the canal. The question that remains is, how do we debride that remaining approximately 40% of the canal surface that has not been cleaned by instrumentation? The answer is irrigation: What do we use, and when do we use it for optimal debridement and disinfection

        

[drmithila]

Lubricants
Lubricants are used to make instrumentation easier. They reduce the friction between the endodontic instrument and the canal wall. Removing dentin by either hand instrumentation or mechanical instrumentation becomes much easier if the canal is wet or lubricated. Instrument lubrication can be achieved easily by using either sterile water, saline, or sodium hypochlorite (NaOCl) for most routine cases. These are readily available and inexpensive. There are also many commercial products currently being sold on the market today specifically for use as instrumentation lubricants. Most are some form of 17% ethylenediaminetetraacetic acid (EDTA) in liquid, gel, or paste formulations. Clinically, I have not found that any particular physical phase of the EDTA makes it a more effective lubricant than any other. However, only liquid 17% EDTA is easy to get into the canal, coats all the walls, and is easy to get out of the canal when I am finished using it. Therefore, I prefer 17% EDTA Plus (Essential Dental Systems) in water for use as a lubricant when instrumenting tight canals because it contains a surfactant which enables the EDTA to wet the canal walls more easily (Figure 1).

Disinfectants
The disinfectant category of irrigants comprises several products. The most frequently used irrigant is NaOCl. This irrigant has 2 great advantages: (1) it dissolves necrotic tissue, and (2) it kills bacteria quite effectively. In water, NaOCl ionizes to produce Na+, hypochlorite (OCl) and hypochlorous acid (HOCl). HOCl is the active moiety responsible for bacterial inactivation.12 The hypochlorous acid must be in direct contact with the bacteria in order to damage the membrane and kill the bacteria. Direct contact with bacteria and flow of the hypochlorite into the apical area is often quite difficult in canals that are not instrumented to wider apical diameters. Boutsioukis et al13,14 have demonstrated that root canal enlargement to greater than a size 25 appears to improve the performance of syringe irrigation. They also noted that increase tapering (.06) improved irrigant replacement. It has been shown that the presence of dentine caused delays in the killing of Enterocococcus faecalis using 1% NaOCl.15 In addition, E faecalis has been demonstrated to be more resistant to killing by NaOCl than Candidia albicans and Gramnegative rods.16-18 E faecalis has also been found to be present in many failed endodontic treatments. It would seem that the longer the hypochlorite is in contact with the bacteria and tissue, the better the outcome. Stojicic et al19 reported that dissolution of tissue increased almost linearly with the concentration of NaOCl.
They also reported that higher temperatures and agitation considerably enhanced the efficacy of NaOCl. The effect of agitation on tissue dissolution was greater than that of temperature. However, it has been reported by Sirtes20 that there is a 100-fold increase in killing efficacy between corresponding NaOCl solutions at 20°C and 45ºC (113ºF). Preheating NaOCl solutions appears to improve their necrotic pulp tissue dissolution capacity and efficacy against E faecalis cells. Al-Jadaa et al,21 in simulated curved canals, showed that passive ultrasonic irrigation (PUI) with a Ni-Ti tip promoted superior tissuedissolving ability than sonic irrigant activation while maintaining canal anatomy.
In order to take full advantage of the physical properties of NaOCl, I both heat it and use PUI to activate it. Brito et al22 tested the efficacy for killing E faecalis in vitro when using 3 different irrigation techniques. The researchers used conventional irrigation with NaviTip needles (Ultradent Products), conventional irrigation with NaviTip needles and activation with the EndoActivator (DENTSPLY Tulsa); then lastly, irrigation with the EndoVac system (Discus Dental). The EndoVac system is an apical negative pressure irrigation system. Brito et al22 found that, of any one of the irrigation techniques evaluated in their in vitro model, there was no evident antibacterial superiority.
Keeping these research facts in mind, the question then becomes: How do we formulate our endodontic irrigating protocol to make maximum use of the physical properties of NaOCl? The majority of my instrumentation is done using warmed 6% NaOCl as the irrigant. I place NaOCl in the canal using a drop-by-drop method (Figure 2). It is the chemical action of the NaOCl that does the work, not the washing of the canal with the irrigant. Drop by drop placement in the canal greatly reduces the risk of any hypochlorite accidents. This problem occurs when the hypochlorite is extruded past the apex and into the surrounding tissue. I also fill the entire access cavity with NaOCl (Figure 3). As the endodontic instrument is placed into the access cavity and then into the canal, it drags along some of the irrigant via capillary action into the canal. The hypochlorite in the access cavity and in the canal will also act as a lubricant that will facilitate easier instrumentation.

        

[drmithila]

Chelating Agents
The last category of root canal irrigants is chelating agents. Chelants are chemicals that form soluble complex molecules with certain metal ions, inactivating the ions so that they cannot normally react with other elements or ions to produce precipitates or scale. In dentistry, chelating agents bind with calcium and carry it out of the canal. The chelating agent most used in endodontics is EDTA. The smear layer, which covers the dentinal tubules, is created during the instrumentation procedure and is composed of dentin, liquid from the irrigants, and tissue debris (Figure 8). Removal of the smear layer from the root canal wall is a key step in endodontics. We would like to remove the smear layer and expose the dentinal tubules for 2 reasons (Figure 9). One reason is to allow the endodontic sealer to penetrate into the tubules for a more intimate fit, hopefully better sealing of the canal. Secondly, by removing the smear layer, and consequently opening up the tubules, we can expose the bacteria that are living there and causing apical periodontitis. Once exposed, the bacteria are susceptible to the disinfecting irrigants we use.
All these irrigants must be able to come into direct contact with the bacteria in order to kill them. If the smear layer is intact, it is impossible for either NaOCl or CHX or any other material to come in direct contact with the bacteria or biofilm. The next question then becomes: How long do we leave the EDTA in contact with the canal to remove the smear layer? Teixeira et al32 showed that EDTA irrigation for one, 3, and 5 minutes were equally as effective in removing the smear layer. Crumpton et al33 showed efficient removal of the smear layer with a final rinse of one mL of 17% EDTA for one minute. Therefore, I use 17% aqueous EDTA for at least one minute in each canal, and I also activate the EDTA by using PUI

        

[drmithila]

The necessity to achieve thorough disinfection of diseased pulpal systems is well understood and documented.1 Our relentless aspiration to eliminate all irritants within a diseased pulpal system remains a committed objective. Unfortunately, our ultimate goal to completely disinfect every root canal system has not yet been practical. Hence the terminology of disinfection opposed to sterilization. The challenge of dissolving tissue and killing or eliminating all bacteria from deep complexities that exist within the randomness that is pulpal anatomy has been a difficult challenge to overcome. Figures 1a to 1d reveal original anatomy of premolars reconstructed from a microcomputed tomography technique.2 Adding to the challenge of pulpal anatomy is the porosity of the dentin and the ability of bacteria to penetrate and flourish within the root structure. However, our pursuit for complete disinfection through root canal treatment has gained significant advancement with the help of recent technological improvements. In addition to improving debridement, these innovative advances have greatly increased our potential to safely and actively disinfect even the most anatomically complex spaces.
SHAPE DICTATES DISINFECTION
Pioneering clinicians who have come before us have blazed the trail that guides our current principles and techniques. Likewise, carving the trail during shaping of the root canal system guides successful disinfection. Shape sets the stage for effective disinfection because the space that is established allows for disinfectants to reach full potential. Although “Cleaning and Shaping” are done concurrently, there is value that comes when considering disinfection as beginning after the desired shape has been accomplished.3 Said differently, there is greater potential to fulfill 3-D disinfection of the entire root canal system after the instrumentable aspect of the root canal system has been addressed. Traditional endodontic techniques are based on the theory that files shape and irrigants clean.4 This statement highlights the knowledge that there are uninstrumentable areas of pulpal anatomy. This complicated mandibular molar contains branches that communicate among the main systems, fins, and multiple portals of exit. Although this type of anatomy is difficult, we are empowered to more effectively engage such complexities with our irrigants through modern irrigation techniques after the main systems have been opened. is an annotative model of a similar tooth, which assists in visualizing these complexities.5
When establishing the desired shape of the root canal system, it is logical to respect a balance between the shape needed to accomplish sufficient disinfection and the need to conserve tooth structure. Individual practitioners have preferences in this regard; however, one proponent that seems to be widely accepted is the need for a deep apical shape. This need for a deep shape stems from physical and biologic standpoints. Anatomical studies have shown that there are an increased frequency of lateral ramifications present at the apical region of canals.6 Microbiology studies have documented that diseased pulpal systems are more advanced and virulent at this critically important apical zone.7 demonstrates a safely produced deep apical shape, which aided in the treatment of this common apical branching. gives example of the reproducible healing potential that occurs when these apical lateral systems are disinfected.
The amount and time of use of an irrigant also holds great value in disinfection. illustrates a good reservoir of irrigant that promotes high levels of disinfection. In this modern era of efficient shaping techniques it is beneficial to remember that a shaped system does not equal a cleaned system. Many clinicians have routinely accounted for this by utilizing a postshaping soak time. This passive soak time has evolved into a time for a more active form of 3-D disinfection

        

[Drsumitra]

ENDOVAC TECHNOLOGY
Few devices come along that can truly be considered game changing advances to a field of specialty. The EndoVac system (Discus Dental) can be considered such a device for the irrigation and disinfection of endodontic procedures. This system utilizes vacuum forces to produce negative pressure irrigation. Although the concept of negative pressure irrigation has been around for some time, this innovative device now allows for its widespread use. views of the various components of this system. Negative pressure irrigation harnesses vacuum forces for the safe delivery of irrigants to the apical region of root canal systems.9 In addition to safely avoiding traditional complications related to positive pressure delivery of irrigants, this technological advancement has had an overwhelming impact on the efficacy of irrigation.10 Furthermore, the EndoVac system’s inherent ability to directly remove pulpal tissue, debris, and bacteria increases levels of debridement.11,12 Like shape, debridement sets the stage for higher levels of disinfectionThe EndoVac technique has shown particular aptitude in delivering irrigant to the critically important apical region.9 The EndoVac system delivers the disinfecting solution to the coronal aspect of the pulpal system and draws the solution to the apical region by way of evacuation. This technology overcomes the limitations of solution surface tensions and possible complications related to air bubbles inhibiting delivery of irrigants to deep, difficult to reach areas of pulpal systems.13 This complication of traditional irrigation has the potential to occur in the closed system of a root canal when sodium hypochlorite (NaOCl) interacts with tissue or debris. When this occurs, an accumulation of vapor (termed apical vapor locks) may be produced which can inhibit further progression of NaOCl to apical zones of the root canal system The ability of the EndoVac to successfully deliver irrigant to the critically important apical region has emboldened clinicians to aggressively yet safely disinfect at or near the terminus. Clinical experience has also shown efficacy in establishing drainage from periradicular tissues in cases of acute swelling. EndoVac’s ability to remove intracanal debris, as it was instrumental in retrieving this separated instrument from around the curve of this mandibular second molar. In addition to facilitating the delivery of solution to all levels of the root canal system, it has been shown that the continuous movement of the solution increases microbial hydrolysis

        

[Drsumitra]

ENDO ACTIVATOR
ENDOACTIVATOR
Increasing the efficacy of our irrigants helps overcome obstacles that are inherent within difficult to reach, intricate anatomy of pulpal systems. Attempts have been made to establish techniques and devices that help us prevail over the limitations that are present from the randomness that is root canal anatomy. At the forefront of methods to activate solutions for penetration into these complex spaces is the EndoActivator system (DENTSPLY Tulsa Dental Specialties).shows this sonically driven system designed to produce a hydrodynamic phenomenon. The increased exchange of irrigant produced by the EndoActivator, illustrated in Figure 8, enhances disinfection by improving solution circulation and penetration into anatomically complex spaces.15 In addition to increasing the penetration of our solutions, the forces generated may increase the biological activities of our irrigants. This safe activation of irrigants allows for bombardment of the solutions into remote, difficult to reach areas that exist within the recesses of pulpal systems. the challenge of reaching such small spaces that are distant from the main pulpal system. Even in vital cases, this holds significant importance, as retained tissue inhibits complete obturation. Moreover, this retained tissue serves as a future nutritional source for bacteria and therefore greatly impacts failures. In addition to the need to reach these remote areas of pulpal anatomy, our efforts need to extend even further. Bacteria have been shown to penetrate and colonize within dentinal tubules of an infected root canal system.electron micrograph of the anatomy of dental tubules. Bacterial have been shown to commonly penetrate into these tubules within diseased root canal systems

        

[drmithila]

 

 

        

[drmithila]

        

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