Barry Musikant

Researchers’ General Conclusions
While the speakers were not recommending culturing, they generally came to the following conclusions:

1. All vital cases should definitely be done in one visit for less post-operative pain. This conclusion is partially based on the following one.
2. All temporary filling materials leak; cavit allows the least amount of leakage.
3. In multiple visits, any reduction in bacteria as a result of the first visit will be repopulated with bacteria by the second visit.
4. The toughest cases to achieve success are not bacterially infected but fungally infected.
5. If some bacteria are left after adequate obturation, they are generally
• entombed
• subjected to reduced nutritional conditions
• incapable of reaching vital tissues
• rendered non-viable by the canal medications
• in a small percentage of cases, capable of survival and able to prevent healing

Researchers’ General Recommendations
The reality of endodontic therapy is that we do not know if we have all of the bacteria or fungi in the root canal after treatment and if we do, what specific organisms they are. The researchers generally offered these recommendations:

1. Widen the apices of canals to at least a #30 instrument with a significant coronal flare. This not only physically removes bacteria and disengages dentin, but allows adequate space for NaOCl irrigation.
2. Have an excellent coronal seal, because data shows that long-term success is as dependent on the prevention of coronal leakage as it is on an apical seal.
3. Prevent gutta percha from going over the apex. Most of us originally learned that one of the reasons gutta percha makes an ideal filling material is its inert nature when in contact with periapical tissues. Research was presented that shows gutta percha over the apex has the potential to also interact with the macrophage cells to induce bone and root resorption. This detrimental effect is enhanced when the gutta percha has been degraded into a less stable structure as a result of chemical softening with chloroform or the application of heat during thermoplastic obturation procedures.
4. NaOCl is used in concentrations ranging from 2.6% to a full 5.25%. The higher the better as long as the application does not allow for periapical extrusion under pressure.
5. Ca(OH)2 is a good inter-visit medication when a case is highly infected. 

1. Our practice is on the right track in using our Simplified Endodontic Technique, (S.E.T.) as our endodontic guide because it widens and tapers the canals enough to efficiently irrigate them with NaOCl 5.25%.
2. S.E.T. places a gutta percha point thoroughly coated with an epoxy resin (EZ-Fill) into the confines of the canal. Because it is a single cone system, the gutta percha is not subject to vertical or lateral condensation that could force the point into the periapical tissues, inducing a macrophage interaction resulting in bone and root resorption.
3. Epoxy resins have their own anti-bacterial and anti-fungal properties as the material sets, rendering any remaining bacteria and fungi less viable.
4. Epoxy resin cements offer the most resistance to coronal leakage due to their polymer structure, unlike ZOE based cements that are particulate in structure and disintegrate far more readily in the presence of moisture.

Single-Use Endodontic Instruments
One of the researchers brought up the idea of using endodontic instruments for only one visit and then discard them because they incrementally dull with usage and are more prone to fracture over time.
   I strongly object to this idea! 
    The advent of Ni-Ti instruments has given the dentist an armamentarium that has increased the cost of each instrument from approximately $.70 per instrument to $7.00 per instrument. 
    Unlike tough and inexpensive stainless steel, Ni-Ti is vulnerable to fracture, especially when instrumenting curved canals. Yet the instrumentation of curved canals are where they are most needed to prevent canal distortions such as transportations and zipping. The fact that Ni-Ti instruments have their greatest potential to fracture in these situations where they are most needed represents an ironic paradox set before us. 
    The manufacturers of these Ni-Ti instruments would love us to use systems composed of expensive and vulnerable instruments and to dispose of them after one visit to reduce the fracture incidence during their usage and the potential for subsequent lawsuits. Rather, I strongly believe that using a hybrid system of stainless steel and Ni-Ti that takes advantage of the strengths of each and de-emphasizes the weakness of each represents a far more rational system than the wholesale replacement of Ni-Ti files after a single usage. 
    S.E.T. specifically addresses these issues. Those using the system have found that fracture of the few Ni-Ti files used is a rare occurrence and when it does occur it is generally in your hand and not in the root. The simple bending test that we do before placing a Ni-Ti instrument into the canal quickly determines if the instrument has enough strength for use in shaping the canal without fracture. Because of our emphasis on stainless steel and the high number of times we can use Ni-Ti instruments before discarding them, the cost of S.E.T. instrumentation is minimal compared to all of the systems being advocated today. 
    Interestingly, the viewpoint of single usage derives from the academic circles where instruments are often donated to the dental schools by the manufacturers in the hope of influencing dental students to become future customers. It is far easier to advocate single usage when the economic impact of that decision does not hit you directly. 
    I know that I am not alone in rebelling against a system that increases the cost more than ten-fold without any effort to see whether the end point of the instrumentation, namely the shape of the canal, could be attained in a more efficient and economical manner as advocated by S.E.T. We are far better off as practitioners when we exchange and develop information about techniques rather than rely solely on “facts” that are presented by manufacturers and marketers.