By Barry Musikant
The lesion has its origins in endodontics if it is accurately defined as endo-perio. If the lesion starts out as a periodontal problem it is perio-endo in genesis. Diagnosing the differences is crucial in optimizing treatment. For example, if one believes the problem is endo-perio, the pulp at a minimum would most commonly be totally non-vital eliciting no response to thermal or electrical pulp tests.
It is highly unlikely that a true endo-perio lesion would also produce a vital pulpal response. Nor would one expect successful resolution of the periodontal defect if endodontic treatment is done. If a pocket to the apex exists along with a vital response, the chances of resolution are poor to non-existent.
As you can see diagnosis is crucial. I have seen extreme periodontal bone loss as a result of an endodontic lesion extending into the attachment apparatus with complete resolution within a year when endodontics is performed in these situations. On the other hand, a lesion initially the result of endodontic infection, may still fail periodontally if so much time has gone by that the pocket is now lined with epithelial tissue preventing its fibrous reattachment to the cementum on the external surface of the root. The endodontic problem may have been resolved, but the periodontal situation remains because reattachment is no longer possible without physically removing it and preventing the growth of a new epithelial lining.
If an infected pulp can destroy periodontal tissue, how does a periodontal problem involve the pulp? For one, a periodontal problem may be chronic and recognized by the dentist. Typically, such pockets are curetted attempting to remove all plaque from the root surface. In so doing, the outer wall of cementum may be stripped from the surface of the tooth exposing lateral canals that now represent a pathway for bacteria to retrogressively invade the pulp tissue. Unlike the endo-perio lesion that has clearly been recognized as a fact, the pathway producing the perio-endo lesion is far less recognized clinically. It is more theory than fact. In either case, a non-vital pulp means endodontic treatment will be done if the goal is to save the tooth. Whereas the endo-perio lesion will often produce resolution of the joint problem with endodontic treatment alone, the perio-endo lesion will still require periodontal treatment and even then the prognosis is far poorer.
As you can we have a diagnostic dilemma, if the perio-endo lesion has advanced to the point that the pulp is non-vital. It is difficult to differentiate it from the endo-perio lesion. The best guide I have for differentiating the two is the fact that periodontal lesions generally are not present around a single tooth. They are common to the whole mouth and often exhibit similar lesions on the contralateral tooth. For example if the lesion in question is tooth # 30, it might be informative to check pocket depth around tooth #19. Seeing periodontal pockets of varying severity particularly in contralateral teeth strongly suggests that the lesion is periodontal in origin with little likelihood that endodontics alone will be successful. With a pocket already established to the apex, it is unlikely that combining endodontic and periodontal treatments will result in success.
Clinically, once the periodontal pocket reaches the apex and retrogressively leads to pulpal necrosis, the resulting pocket is indistinguishable from a lesion that has its origins from a primary necrotic pulp. At this point, with the goal of retaining the tooth, our choice of treatment would be to first fully debride, medicate and seal the pulp chamber with a strong temporary cement. We might wait two weeks to see if the pocket depth and width of the lesion decreases. With the source of the lesion being periodontal we would not expect any such reductions and would then consider scaling, bone grafts, and guided tissue regeneration. Only after the pocket is showing signs of resolution would we then complete the root canal therapy.
Of course, this sequence of treatment is really saying that commitment to complete root canal therapy should only be done if we have clear evidence that the periodontal pocket is resolving. To complete a treatment and charge for it without some positive indication of resolution is based more on misinformed hope rather than sound diagnosis and can potentially be a source of conflict with the patient. Particularly, in an age of implants, other more predictable options exist.
Perhaps, the most important aspect of dealing with endo-perio and perio-endo lesions is making sure what we know and what we don’t know. A non-vital tooth with a thin communication to the apex is likely to resolve with endodontic treatment alone. We know that. A broad pocket to the apex associated with a non-vital tooth in a mouth that also has several other periodontal lesions means the cause of the lesion may be either perio or endo in origin and we don’t necessarily know which. We do know that if we treat it endodontically the lesion may remain. In other words, our treatment is inappropriate despite our best of intentions. The dubious nature of the problem must be conveyed to the patient. They must understand the risks. When the procedures are not predictable in their results, the patient must be told of other more predictable options. Such communications will resolve issues of protocol before treatment and reduce if not prevent any conflicts that might come from a lack of effective prior explanation.
In summary, if we diagnose an endo-perio lesion correctly, we have a predictably high rate of success. Our success is reduced when what we thought was endo-perio was really perio-endo or at best a combined lesion. At a minimum, we should inform ourselves as diagnosticians to be aware when the lesion is not clearly endo-perio. The alternative puts us on potentially shaky ground.