Big subject, big nuisance. These types of lesions can be a devil to diagnose and treat successfully. The main problem is as to which comes first. Periodontic lesion or endodontic lesion? Or is it both?
Careful diagnosis is required followed by a detailed discussion with the patient so that they are fully aware of the implications of such lesions.
Periodontal and endodontic lesions are both anaerobic mixed infections and, according to the classic arrangement (Simon et al 1972), are as follows:
• Primary endodontic with secondary periodontitis
• Primary periodontal with secondary endodontic
• Combined lesions with each area being independently diseased.
Infection can theoretically spread from one area to the other through the apical and lateral canal system and through connections into the furcations of molars. Root perforations and root fractures may also be implicated.
There are a number of ways of differentiating between the two but there are areas of grey that simply confuse.
However, a few important indicators are:
• Tooth vitality. Periodontal lesions are mainly positive with endodontic lesions negative or unclear
• Heavily restored teeth may indicate an endodontic origin. Lack of a restoration (except where trauma may have occurred) is likely to indicate a periodontic lesion.
• Lack of periodontal disease elsewhere in the mouth may indicate endodontic rather than periodontic origin
• Radiographically, an endodontic lesion may show as narrow, U-shaped and with apical involvement. With periodontic lesions the apex may not be involved.
Like many things, I think we need to take a balanced approach, combining all the presenting features and coming to our best diagnosis.
Treatment for a primary endodontic lesion involves root canal therapy. Generally the prognosis for these teeth is good. Primary periodontal lesions are treated via periodontal therapy. The difficulty lies when we are not sure. Do we perform the periodontal therapy first or the endodontic?
It is suggested that the endodontic therapy is performed first to avoid potential damage to the periodontal structures that are capable of regeneration. But what if we are wrong and we have subjected the patient to irreversible treatment?
Sometimes we just have to take the plunge based on our best estimate. If endodontic therapy is performed, it must be done to the highest standards to ensure we give the lesion the very best chance of resolving.
Combined lesions can be a problem and have the worst prognosis. Root resection and hemi-section following root canal therapy may be options. Extraction and replacement with an alternative restoration must not be forgotten as a treatment option. Diagnose the best you can and discuss what the patient would like.