Overview and definition
A periapical scar is a benign post-treatment repair finding, not a disease. It represents fibrous connective tissue healing of a periapical bony defect following root canal treatment or apical surgery, rather than persistent infection or neoplasia.[1][2] Among chronic post-endodontic periapical lesions—classically granuloma, radicular cyst, and scar tissue—scar tissue is the least common and reflects a reparative rather than inflammatory process.[1] Synonymous terminology includes periapical fibrous scar and incomplete (scar tissue) healing under the Rud/Molven radiographic criteria.[2][3] Expected context is a tooth with adequate prior endodontic therapy and an asymptomatic, stable periapical radiolucency on follow-up imaging.[2][4]
Radiographic findings
Recognition and appearance. Under Rud/Molven criteria, incomplete healing (scar tissue) is a radiolucency that has decreased in size or remained stationary, often showing recognizable bone structures within the rarefaction, an irregular periphery sometimes demarcated by a compact bone border, asymmetric location around the apex, or an angular connection with the periodontal ligament space.[3] Stability over serial radiographs is a defining feature.[2][4]
Location. Scars may occur at any treated apex but have been reported more frequently in the anterior maxilla, where through-and-through loss of both the buccal and palatal cortical plates, particularly after apical surgery, favors fibrous rather than osseous repair; granulomas instead predominate in the posterior mandible.[4]
Mimics and discriminators. The principal challenge is distinguishing a scar from persistent apical pathosis—periapical granuloma, radicular/residual cyst, or endodontic failure—since these cannot be reliably separated on conventional radiography alone.[2][5][6] CBCT provides superior three-dimensional assessment of periapical change and detection of subtle failures.[4][7] Lack of progression across prolonged follow-up favors a scar, whereas enlarging radiolucency suggests failure.[3][4]
Management and prognosis
A periapical scar interpreted correctly requires no additional intervention; it is a favorable healed outcome, and recognizing it avoids unnecessary retreatment or surgery.[2][4] Diagnosis rests on combined clinical, radiographic, and—when definitive confirmation is needed—histologic correlation, since asymptomatic persistent radiolucencies are frequently misread as failures.[2] Prolonged follow-up is essential, as periapical healing may take many months.[4] Red flags warranting review or specialist referral include symptoms (pain, swelling, sinus tract), radiographic enlargement, or lesions large enough to raise concern for cystic or non-endodontic pathology.[4][6] In selected equivocal cases, minimally invasive biopsy has been described to confirm fibrous scar before invasive treatment.[2]