August 1, 2006
by Rich Mounce, DDS
In my opinion, the advent of predictable implant therapy is a good stimulus for endodontics. Implant therapy has, in one view, called on endodontics to improve its predictability, safety and efficiency. If endodontics has a rival in implants, endodontics must meet its competition head on. Observance of two key principles, amongst others, can maximize endodontic success. The first is case selection and second is a reduction of coronal microleakage after obturation.
It is axiomatic that non-restorable teeth should be extracted. It is my contention that many failed endodontic results could be avoided if non-restorable teeth were removed before endodontic treatment is started. While the above might seem obvious, as a practicing endodontist, an empirical estimate is that approximately 10-20% of the teeth now referred for treatment in my office are not restorable as they present and require some form of periodontal surgery or extraction. If endodontic therapy were to be performed on such teeth the likely outcome is failure irrespective of the quality of the root canal. Evaluation of teeth to determine which are restorable and which need to be made restorable through periodontal therapy requires careful consideration but through which the clinician can avoid performing endodontic treatment where extraction is indicated.
For example, being able to evaluate whether a tooth can handle the specific load it is being asked to carry as a bridge abutment without undue risk of fracture must be assessed preoperatively. Remaining bone support, mobility and parafunctional forces must all be assessed in addition to the health of the periodontal attachment. The tipping, rotation, and mechanical load that the tooth carries all have vital importance with regard to whether the given tooth can and should be maintained. In addition, if the tooth is already fractured, the clinician must ask what is the chance that the habit that caused the fracture (bruxism or ice chewing for example) will stop and as such the tooth can be restored without undue risk of further fracture. Furthermore, patients must consent to have all the needed future restorative treatment completed. If the patient has a root canal but does not have a proper coronal seal after, success is obviously diminished.
Coronal seal is a simple issue, often misunderstood, and one in which endodontic success can be improved dramatically with its correct accomplishment. The endodontic literature is very clear that gutta percha exposed to saliva leaks in a time dependent fashion. Gutta percha exposed to saliva and its attendant bacterial allows the bacteria to migrate in a coronal to apical direction in days to weeks. Crowns that leak after which root canal treatment has been accomplished (contaminating the gutta percha) and in which the leakage has gone on for any appreciable period of time (days to weeks) need to be retreated before the tooth is restored again. If the tooth is not retreated, the bacterial contamination within the root canal system is sealed into the root. The literature is also conclusive that coronal seal is directly correlated with long-term clinical success for the reasons above. Gutta percha has no inherent ability to resist coronal leakage as gutta percha does not bond to canal walls nor to sealer. Bonded canal alternatives such as RealSeal (SybronEndo, Orange, CA) provide a statistically significant reduction in coronal leakage relative to gutta percha and provide an added layer of protection aside from early coronal seal to diminish the movement of bacteria in a coronal to apical direction.
In summary, amongst others, two critical factors to providing excellent endodontic treatment and improving endodontic success rates have been discussed. The clinician is encouraged to carefully evaluate all selected teeth for endodontic treatment for restorability and consider bonding their obturations so as to provide the highest level of protection against coronal leakage aside from placement of an early coronal seal. I welcome your questions and feedback.
Dr. Mounce lectures globally and is widely published. He is in private practice in endodontics in Portland, OR. He is the endodontic consultant for the Belau National Hospital Dental Clinic in the Republic of Palau. Korror, Palau (Micronesia). Dr. Mounce can be contacted at Lineker@aol.com.
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