Endo-perio lesions might be interdependent because of the vascular and anatomic connections between the pulp and the periodontium.

The aim of this study is to emphasise that primary endodontic lesion heals after a proper instrumentation, disinfection and sealing of the endodontic space.

The primary endodontic lesion with a secondary periodontal involvement first requires an endodontic therapy and, in the second stage, a periodontal therapy. The prognosis is good, with an adequate root canal treatment; it depends on the severity of the periodontal disease, appropriate healing time and the response to the treatment.

A correct diagnosis is sometimes difficult; an accurate identification of the etiologic factors is important for an adequate treatment.

Primary perio-endo lesion may heal after a proper disinfection and sealing of the endodontic system, the one-year follow-up radiograph showing bonny repair. Invasive periodontal procedures should be avoided at that moment.

The microorganisms and by-products from the infected root canal may cross accessory and furcal canals and determine sinus tract and loss of attachment. In both clinical cases presented in this article, successful healing was obtained after a proper disinfection and sealing of the endodontic system.