A root fracture is a break or crack that extends into the root portion of a tooth, involving one or more structural layers — dentin, cementum, and in some cases the dental pulp. Unlike crown fractures, root fractures occur entirely or predominantly below the gingival margin, making them particularly challenging to identify and manage.
Types of Root Fractures
Root fractures are classified by the orientation of the fracture line relative to the tooth’s long axis:
- Horizontal root fractures — run perpendicular to the long axis and are most often caused by traumatic injury; prognosis improves when the fracture is located in the apical third.
- Vertical root fractures — run parallel to the long axis; frequently associated with post placement or excessive endodontic instrumentation; typically carry a poor prognosis and often require extraction.
- Oblique root fractures — run diagonally and share clinical features of both types depending on their depth and extent.
Clinical Significance
Root fractures are notoriously difficult to detect because they present with varied and often subtle signs. Common clinical findings include:
- Pain or sensitivity when biting or chewing
- Increased tooth mobility
- Localized swelling or a draining sinus tract
- Deep, narrow periodontal probing defects adjacent to the fracture line
Disruption to the periodontal ligament is a hallmark of vertical root fractures, explaining why they rarely heal and so frequently lead to tooth loss. Horizontal fractures may allow pulp survival if the fracture lies in the middle or apical third and the tooth is promptly stabilized with a flexible splint.
Diagnosis and Management
Accurate diagnosis relies on a combination of periapical radiography, cone-beam computed tomography (CBCT), transillumination, and meticulous periodontal probing. Standard two-dimensional radiographs frequently miss fractures that are not aligned with the X-ray beam angle, so CBCT has become an essential diagnostic tool in ambiguous cases.
Treatment ranges from splinting and root canal therapy for favorable horizontal fractures to extraction for vertical root fractures or those extending into the coronal third. Intentional replantation or root resection may be considered in carefully selected cases where extraction is otherwise the only option.
Prompt diagnosis using advanced imaging and thorough clinical evaluation gives patients the best opportunity to preserve the tooth — or plan an appropriate replacement — before significant loss of surrounding alveolar bone occurs.