Periodontology Diagnosis
Combined Periodontic-Endodontic Lesions

Combined periodontic-endodontic lesions are local, circumscribed areas of bacterial infection. The lesions originate from either dental pulp, periodontal tissues surrounding the involved tooth or teeth or both.

The endodontium and periodontium are closely related. Diseases which are present in one tissue, can often lead to the involvement of the other. It can be difficult to differentiate the diagnosis of endodontic and periodontal diseases. However, it is critical to make the correct diagnosis to ensure the proper treatment can be provided. Endodontic-periodontal lesions present various challenges to the clinician regarding the diagnosis and prognosis of the involved teeth. Etiologic factors including bacteria, fungi, and viruses in addition to various other contributing factors such as trauma, root resorptions, perforations, and dental malformations, all play an important role in the development and progression of lesions. An endo-perio lesion is a condition which is characterized by the association of periodontal and pulpal disease found in the same dental element. The term ‘perio-endo lesion’ has been used to describe lesions from inflammatory products which are found in varying degrees in both the periodontium and pulpal tissues.
Combined periodontic-endodontic lesions which take the form of abscesses and can originate two locations and are informally classified as follows:

1. Endo-Perio: the infection from the pulp tissue within a tooth which may spread into the bone immediately surrounding the tip, or apex, or the tooth root. This results in the formation of a periapical abscess. This infection may then proliferate coronally in order to communicate with the alveolar bone and the oral cavity by spreading through the periodontal ligament.
2. Perio-Endo: the infection from a periodontal pocket which may proliferate through accessory canals into the root canal of the affected tooth. This can lead to pulpal inflammation. Accessory canals may not be big enough to allow bacterial penetration. As a result, periodontal disease must reach the apex to induce an endodontic lesion.

The prognosis, treatment and expected treatment outcome do not depend on the source of the infection.

The development of a true-combined lesion is identical to that of the development for primary endodontic and periodontal lesions. These lesions are often quite similar from an advanced primary endodontic lesion with secondary periodontal involvement and/or a primary periodontal lesion with secondary endodontic involvement. It is less common to experience a true combined endodontic-periodontal disease. It forms when a coronally progressing endodontic disease joins an infected periodontal pocket progressing apically. The radiographic appearance of a combined endodontic-periodontal disease can be very similar to a vertically fractured tooth. A fracture which has invaded the space of the pulp, with resultant necrosis, can also be labeled as a true combined lesion, and may not be amenable to successful treatment.

Classification of perio-endo lesions

There are four different types of perio-endo lesions. They are classified based on to their pathogenesis.

1. Endodontic Lesions: an inflammatory process in the periodontal tissues. It results from noxious agents which are present in the tooth’s root canal system.
2. Periodontal Lesions: an inflammatory process in the pulpal tissues. This results from the accumulation of dental plaque found on the external root surfaces.
3. True-combined Lesions: This is both an endodontic and periodontal lesion which develops independently and progresses concurrently. It meets and merges at a point along the root surface.
4. Iatrogenic Lesions: Endodontic lesions are usually produced as a result of treatment modalities.

A combined lesion can also be cause by a fractured tooth.

Treatment includes conventional endodontic therapy which is commonly followed by conventional periodontal therapy. If the lesion is classified as too severe for treatment, the affected tooth may need to be extracted.