Classification Simon, Glick & Frank (1972)

1° Endo lesion

1° Endo lesion
==Describes a draining sinus tract from an apical abscess that exits through the gingival sulcus, mimicking a periodontal pocket.==
- This is purely an endodontic problem. The drainage pathway is through bone, not the periodontal ligament, and resolves with root canal treatment alone.
- A furcation radiolucency caused by an accessory canal from an infected root canal system is also just an endodontic problem.
with 2° Perio involvement
1° Perio lesion
1° Perio lesion
==Describes a deep periodontal pocket extending to the apex, causing a radiolucency that mimics an endodontic lesion, but the pulp remains vital.==
- This is purely a periodontal problem. Pulp sensibility tests are normal, and the bone loss resolves with periodontal treatment alone.
with 2° Endo involvement
These categories attempt to describe a situation where one disease process initiates the other.
- Clinically, it is impossible to determine which disease came first once both are established.
“True” Combined lesion

Unlikely…!

Case 1

Pre-op	1 Year Review
CO₂ +	CO₂ +
EPT 34	EPT 15

Case 2: Pulp Sensibility Tests

Date	1/3/17	1/6/17	10/7/17	11/8/17
CO₂	+	+	+	+
EPT	22	20	20	15

Case 3: Pulp Sensibility Tests

Date	19/8/16	4/7/17	1/9/17
CO₂	+	+	+
EPT	22	51	17

Critique of Traditional Classifications[^16][^17]

1º Endo lesion
1º Endo lesion with 2º Perio involvement
1º Perio lesion
1º Perio lesion with 2º Endo involvement
“True” Combined lesion
This describes a tooth with both endodontic and periodontal disease, which is functionally identical to the 'primary/secondary' categories.

Possible Meaningful Useful