Barry Musikant

HE TRADITIONAL viewpoint is that we wish to save our teeth for as long as possible. This viewpoint is no longer as black and white as it was in the past because of the advent of implants. When a tooth is extracted for the placement of an implant, the implication is that the implant will give superior service with a low risk to the patient when this substitution is incorporated.
 I believe that in some cases the choices are obvious. If a tooth is pretty much intact, there is no question that the root canal should be done, provided that the dentist or endodontist has the skills required to do what is considered a good job. If a tooth is so thoroughly broken down that saving it would take heroic efforts and result in only a guarded prognosis, there is no question that an implant should be considered if the bone is present to accept it and the health of the patient does not contraindicate it.
    So what we are really talking about is the gray area, where dentists may differ in opinion on what should be placed. The most recent studies show that, statistically, implants and endodontics enjoy a similar rate of success, although it has been pointed out that implants require significantly more maintenance. I have heard some dentists argue that if a tooth needs a post, they would rather place an implant. However, the only purpose of a post is to supply adequate coronal retention of the core. If done correctly, the post should produce minimal insertional stresses and then act as a distributor of functional stresses. Given adequate bone support and the placement of a crown with a ferrule of approximately 2 mm, a long-lasting restoration should be the result.
    Now the suggestion has been raised that teeth that have had endodontics and a post are vulnerable to fracture when supporting long-spanning bridges where two or more teeth are missing. I believe this to be the case, too. However, these are exactly the cases in which the patient would be better off if implants were placed in the edentulous areas, negating the need for a long-span bridge and taking the stress off the posted abutment, simply because it is no longer an abutment. It is, instead, a single-unit tooth built up with a post that has to support only itself. The longevity of this type of restoration is well established.
    To the extent that an implant does not have to be placed, a surgical procedure is eliminated. The implants go significantly deeper than the roots of a tooth. The possibility of hitting vital structures has to be evaluated and avoided, but risk is increased. From the two-year implant course that I took fourteen years ago, I clearly remember that when laying back a flap for the placement of posterior mandibular implants, the first requirement as the flap was being raised was to locate the mental nerve as it exited the cortical plate. With the placement of implants, we want to be aware of all the structures that we must avoid.
    The above precautions are not meant to discourage the placement of implants when they are required, only to emphasize the skills that are necessary to place the implants without negative consequences. On the other hand, full respect should in my opinion be given to the ability of well-done endodontics to maintain the usefulness of teeth. The incorporation of posts that produce high retention, minimal insertional stresses, and an even distribution of functional stresses allows many teeth to have years of useful service without subjecting the patient to more elaborate and expensive procedures.
    One self-defeating practice that may have encouraged the extraction of posted endodontic teeth is the use of fiber-reinforced posts. Standing alone, teeth reinforced with fiber posts will bend far more than teeth posted with metal posts. Imagine how much more they will bend when the abutment teeth must support the function directed to two or more pontic areas. Their rapid failure could easily lead one to the conclusion that the combination of posts and cores is a poor idea in all situations. Although I don’t recommend that posted teeth be used as terminal abutments for long-span bridges, this cautionary note is magnified several times when the post is fiber and not metal, or when the metal causes either high insertional stresses or a concentration of functional stresses.
    The major cause of concern in using a tooth rather than an implant is the tooth’s questionable ability to remain intact and not split under function. Given this concern, implants if allowable should be placed wherever edentulous areas already exist. Posted teeth should stand alone wherever they can or should be tied to other teeth without any intervening abutments.
    I write this article from the perspective of an endodontist whose goal is to maximize the potential of the existing dentition. As such, my criteria for what I can save may be broader than those of a restorative dentist, who may be suspicious of teeth that are so broken-down that they require a post. If a tooth has sound periodontal support, at least 10 mm of bone support, and solid remaining tooth structure—even if the remaining tooth is at the level of the gingiva, the buildup of this tooth with a post of the correct design and restored with a crown providing a 2 mm ferrule will provide long-lasting usefulness.
    Ultimately, I like to do things in as risk-free a manner as possible. Before I do apical surgery, particularly on mandibular molars, I will first attempt to retreat the case conservatively. If a post exists, I will remove the post with minimal loss of tooth structure (working under the microscope) and then proceed with the retreatment. This approach has produced far more successes than failures and, most importantly, has substituted a less-traumatic procedure for a more-traumatic one. In like manner, if I can build up a tooth so that it can be maintained, thus avoiding the placement of an implant, I will have avoided a surgical procedure, the need for the correct analysis of tomographic radiographs (assuming we are being most cautious), surgical stents, a long period of integration (assuming immediately loaded implants are not being used, which brings up an entirely different discussion), and highly expensive procedures that are not covered by insurance.
    In summary, there are clearly demarcated areas where the implant-versus-endodontics discussion is not germane because the correct choice is obvious. Only in those areas where the capabilities of endodontics and the subsequent buildup of teeth are not recognized or are recognized as negative from previous experiences do the differences of opinion become apparent. Certainly, the financial implications to the dentist should never be a consideration except as they affect the dentist’s ability to deliver a more affordable service to the patient.