Tooth Prognosis Classification (Samet & Jotkowitz)
A comprehensive, standardized classification for assigning a relative prognostic value to individual teeth during treatment planning. From Samet & Jotkowitz, Classification and prognosis evaluation of individual teeth—A comprehensive approach (Quintessence Int 2009;40:377–387). See source: Classification and prognosis evaluation of individual teeth—A comprehensive approach.
Each tooth is evaluated against four criteria: periodontal support, restorability (remaining sound tooth structure incl. ferrule), endodontic condition, and occlusal plane/position. The single most severe criterion sets the class.
Core 5-Class System
| Class | Prognosis | Periodontal support (approx bone %) | Remaining tooth structure / restorability | Endodontic condition | Occlusal plane / position |
|---|---|---|---|---|---|
| A | Good | 80–100% bone support; easily maintained | 80–100% sound coronal structure; easily restored, adequate ferrule | Straightforward primary RCT, or existing good endodontic therapy | Correct plane/position, or slight deviation needing minimal enameloplasty |
| B | Fair | 50–80% bone support; maintainable with rigorous therapy; treatable vertical defects/furcations (molars higher risk) | 50–80% sound structure; restorable with no biologic-width infringement, adequate ferrule, good crown–root ratio | Failing RCT with obvious cause, predictably retreatable; or difficult primary RCT | Out of plane but adjustable to function within correct plane (may need to seal exposed dentin) |
| C | Questionable | 30–50% bone support; no acute outbreaks but cleansability difficult; maintainable for acceptable period | 30–50% sound structure; ferrule achievable only by compromising crown–root ratio and/or adjacent structures | Acute/chronic failing RCT, difficult to retreat predictably | Out of plane; requires multiple procedures to function within plane |
| D | Compromised | < 30% bone support; cannot be cleansed/maintained well; active periodontal disease | < 30% sound structure; ferrule not achievable without compromising adjacent support or crown–root ratio | Failing RCT that cannot be predictably retreated | So severely out of plane/tilted that post-treatment crown–root ratio prevents long-term service, or position harms adjacent structures |
| X | Nonsalvageable (extract) | < 30% bone support with unavoidable acute periodontal outbreaks | No remaining supragingival sound structure; loss deep into root dentin/canals | Vertical root fracture, or repeatedly retreated (endo/surgical) without resolution | So super-erupted/tilted it cannot be restored to function or blocks restoration of either arch |
Step 1 of analysis
Evaluate severity both as presented and as foreseen after caries removal. Class D differs from X in that there is no active indication for extraction — external/patient factors decide whether to invest in the tooth.
Class-Dropping Modifiers (Step 2)
These factors can drop a tooth one class (more than two findings may drop it further):
- Anatomic irregularities — irregularly shaped, thin, short, or excessively conical roots; multiple canals and/or roots. Can render an otherwise fair/poor tooth critical or hopeless.
- Iatrogenic compromising factors — perforations, extensive post preparations, minimal remaining wall thickness after preparation, non-removable dental materials. Prognosis may stay fair/good without active pathology, but drops once further treatment is planned or other signs/symptoms appear; may even indicate extraction.
Patient-Level Risk Modifiers (Step 3)
A drop of one class for all teeth is suggested when considerable patient-level risk factors are present. Reassessed over time — drop further if modifiable factors are uncontrolled or significant nonmodifiable factors exist; raise a class when modifiable factors clearly improve.
- Biologic — impaired immune function/healing, reduced salivary flow, disability limiting hygiene, high S. mutans/Lactobacillus counts, IL-1 genotype, family history, other missing teeth.
- Behavioural — poor oral hygiene, cariogenic diet, low fluoride exposure, parafunction, smoking, non-adherence to long-term maintenance.
- Financial / personal — motivation for treatment, available resources and willingness to commit time/finances, attitude to tooth loss, low dental IQ, esthetic expectations.
Application in Treatment Planning
- Evaluate each tooth against the four criteria; the most severe sets the base class.
- Apply tooth-level modifiers (anatomic, iatrogenic) to drop the class where applicable.
- Apply patient-level modifiers to shift the prognosis of the whole dentition.
A tooth re-graded to Class C or D may be unsuitable as a planned bridge abutment, prompting an alternative plan; conversely, patient goals and finances may justify retaining such teeth as individual interim units. Esthetics influence the treatment choice but do not alter tooth prognosis per se.