15.4 Endodontic-Periodontal Lesions, Cracked Teeth and Vertical Root Fractures
Key Takeaways
In an endodontic-periodontal lesion with a necrotic pulp, root canal treatment is done first and the periodontal component is re-evaluated after healing, because a lesion of endodontic origin may resolve without periodontal surgery.
Primary endodontic lesions have the best prognosis, while true combined and primary periodontal lesions depend on the extent of periodontal destruction; endo-perio lesions with root damage (fracture, perforation, external resorption) have a poor prognosis.
The AAE classifies cracks as craze lines, fractured cusp, cracked tooth, split tooth and vertical root fracture; a split tooth is a cracked tooth whose crack has become complete.
A vertical root fracture typically shows an isolated narrow deep pocket, a sinus tract near the gingival margin and a J-shaped or halo radiolucency, usually in a root-filled tooth.
A vertical root fracture has a hopeless prognosis for the affected root, so the tooth is extracted or, in a multi-rooted tooth, the fractured root is resected.
Two endodontic blueprint subsections, endo-perio lesions and vertical root fracture, test whether you can identify where a lesion started and whether the tooth can be saved. Cracked teeth belong with them because they produce similar narrow pockets and pain patterns.
Pathways Between Pulp and Periodontium
- Apical foramen: the main route.
- Lateral and accessory canals, including furcation canals in molars.
- Dentinal tubules exposed by cementum loss, scaling or recession.
- Iatrogenic and pathological pathways: perforations, fractures, resorption.
Classification
Classical (Simon, Glick and Frank, 1972):
| Lesion | Origin | Pulp | Key features |
|---|---|---|---|
| Primary endodontic | Pulp necrosis draining through the PDL | Non-vital | Narrow sinus-like pocket; heals after root canal treatment |
| Primary endodontic with secondary periodontal | Untreated endodontic drainage with plaque colonization | Non-vital | Plaque and calculus in the drainage tract |
| Primary periodontal | Periodontitis progressing apically | Vital | Generalized bone loss, wide pockets |
| Primary periodontal with secondary endodontic | Deep periodontitis reaching lateral canals or apex | Becomes non-vital | Long history of periodontitis |
| True combined | Independent lesions that meet | Non-vital | Both components present |
2017 World Workshop: endo-periodontal lesions with root damage (root fracture or crack, root canal or pulp chamber perforation, external root resorption) have a poor prognosis; lesions without root damage are graded by the extent of pocketing (narrow deep pocket on one surface, wide deep pocket on one surface, deep pockets on more than one surface) in patients with or without periodontitis.
Diagnosis
- Pulp testing (cold and electric): a necrotic pulp points to an endodontic origin; a vital pulp makes a primary periodontal lesion likely.
- Probing pattern: a single narrow, deep defect suggests endodontic drainage or a fracture; wide, generalized pockets suggest periodontitis.
- Trace a sinus tract with a gutta-percha cone on a radiograph.
- Radiographs and limited-field CBCT for lateral lesions, furcation involvement and resorption.
Treatment Sequence and Prognosis
- Primary endodontic lesion: root canal treatment only; the "pocket" often closes because it is a drainage tract.
- Combined lesions with a necrotic pulp: root canal treatment first, then re-evaluate the periodontal component after about 2-3 months before periodontal therapy or surgery.
- Primary periodontal lesion with a vital pulp: periodontal therapy only; do not perform elective root canal treatment.
- Prognosis: best for primary endodontic lesions, intermediate for primary endodontic with secondary periodontal, and worst for primary periodontal and true combined lesions with extensive attachment loss.
Cracked Teeth: AAE Classification
| Type | Features | Typical management |
|---|---|---|
| Craze lines | Enamel only; common in adult anterior teeth | No treatment (esthetic only) |
| Fractured cusp | Complete or incomplete fracture of a cusp, often next to a large restoration; pulp usually vital | Remove the loose cusp and restore with cuspal coverage |
| Cracked tooth | Incomplete crack from the occlusal surface extending apically, usually mesiodistal; sharp pain on biting and on release | Cuspal-coverage crown (a band or provisional crown can confirm the diagnosis); root canal treatment if the pulp is irreversibly inflamed |
| Split tooth | A cracked tooth whose crack is complete, separating the tooth into segments | Usually extraction; occasionally remove one segment and restore |
| Vertical root fracture | Starts in the root, buccolingual, usually in root-filled teeth | Extraction or root resection |
Diagnostic aids include the bite test (for example a Tooth Slooth) to reproduce release pain, transillumination, magnification, methylene blue dye, and probing for narrow defects. Cracks are often invisible on radiographs.
Vertical Root Fracture
Risk factors: excessive canal enlargement and loss of dentin, wedging forces during lateral compaction, tapered and oversized posts, heavy occlusion.
Signs:
- Isolated, narrow, deep periodontal pocket, often on the buccal or lingual surface.
- Sinus tract close to the gingival margin rather than at the apex.
- Radiographically a J-shaped (halo) radiolucency along the root, widened PDL, or separation of root fragments.
- Mild symptoms, discomfort on biting, recurrent swelling.
Confirmation often needs flap exploration or CBCT, though root fillings and posts create artifacts. Because the fracture cannot be sealed predictably, the prognosis of the fractured root is hopeless: extract the tooth, or resect or hemisect the affected root in a multi-rooted tooth with adequate support.
Differential Diagnosis: Resorption and Perforation
External cervical (invasive) resorption enters the root below the epithelial attachment and can mimic an endo-perio lesion or caries; the pulp is often vital and separated from the defect by a thin predentin layer, giving a pink spot on the crown in some cases. CBCT maps its extent; treatment is surgical debridement and restoration, or root canal treatment when the pulp is involved. A root perforation made during treatment produces a sudden bleeding point and a narrow defect; it is repaired promptly with MTA or a bioceramic, and its prognosis depends on its level relative to the crestal bone.
Root Resection and Hemisection Criteria
Removing a fractured or hopelessly involved root from a multi-rooted tooth is reasonable when the remaining roots have good bone support, the tooth is strategically important, root canal treatment of the retained roots is feasible, and the patient accepts a restoration that changes the tooth's form. Long, fused or closely approximated roots are poor candidates.
Exam Traps
- Do not perform periodontal surgery first on a lesion with a necrotic pulp; root canal treatment comes first.
- A narrow deep pocket on a root-filled tooth with a post is a vertical root fracture until proven otherwise.
- "Pain on release of biting" points to a cracked tooth, not irreversible pulpitis.
Tooth 36 has a necrotic pulp, a narrow 8 mm pocket on the mesial and a radiolucency extending from the apex to the crest. The rest of the mouth is periodontally healthy. What is the correct initial treatment?
Systemic antibiotics only, because the narrow pocket is just a sinus-like drainage tract
Periodontal flap surgery with regeneration first, then root canal treatment later
Root canal treatment first, then re-evaluate the periodontal defect after healing
Extraction immediately, because any endo-perio lesion has a hopeless prognosis
A root-filled tooth 15 restored with a post-retained crown has an isolated 9 mm narrow buccal pocket, a sinus tract near the gingival margin and a J-shaped radiolucency along the root. What is the most likely diagnosis and treatment?
Cracked tooth, treated by placing a new crown with a deeper margin
Vertical root fracture, with extraction as the usual treatment
Lateral canal infection, treated by repeating the root canal filling
Primary periodontal lesion, treated by scaling and root planing
A crack that began on the occlusal surface of tooth 47 has progressed so that the tooth now separates into mesial and distal segments that move independently. How is this classified by the AAE?
A craze line limited to the enamel
A fractured cusp with a vital pulp
A vertical root fracture from the apex
A split tooth (a complete crack)
Sections you finish are checked off in the contents.