11.2 Prognosis Determination & Presenting Treatment Alternatives
Key Takeaways
- Prognosis is determined tooth by tooth and for the dentition overall, and the overall prognosis can be worse than the sum of individual teeth when systemic or behavioral risk is high
- Crown-to-root ratio, furcation involvement, mobility, remaining attachment, restorability, and endodontic status are the primary tooth-level prognostic factors
- Smoking and uncontrolled diabetes are the two modifiable patient-level factors that most reduce periodontal and implant prognosis
- Every treatment presentation must include the option of no treatment and its expected consequences
- A questionable tooth used as a fixed partial denture abutment converts a single-tooth risk into a multi-unit failure, which is why implant or removable alternatives are often preferable
Prognosis Determination & Presenting Treatment Alternatives
Why this matters on the INBDE: A treatment plan is a prediction. Clinical Content area 4 asks you to use clinical and epidemiological data to establish a prognosis, and area 13 asks you to discuss alternatives and prognoses with the patient. Case items reward the answer that is both biologically defensible and honestly communicated.
Prognosis Classification
A widely used classification, adapted from McGuire and Nunn and from periodontal literature:
| Prognosis | Definition |
|---|---|
| Good | Adequate remaining support; etiologic factors controllable; patient cooperative; no systemic complication |
| Fair | Slightly reduced support, Class I furcation, or slight mobility; etiologic factors controllable; adequate maintenance possible |
| Poor | Moderate to advanced attachment loss, Class II furcation, mobility; maintenance difficult |
| Questionable | Advanced attachment loss, Class II or III furcation, mobility Class II–III, inaccessible areas; the outcome cannot be predicted |
| Hopeless | Inadequate remaining support to retain the tooth; extraction indicated |
A hopeless designation is not a failure of care; it is a decision that allows resources to be directed where they will succeed. Retaining a hopeless tooth in a strategic position can be justified temporarily — for example, as an interim overdenture abutment — but the reasoning must be documented.
Tooth-Level Prognostic Factors
| Factor | Favorable | Unfavorable |
|---|---|---|
| Remaining attachment / bone support | Loss under one-third of root length | Loss beyond one-half to two-thirds |
| Crown-to-root ratio | 1:2 ideal; 1:1 acceptable as an abutment | Greater than 1:1 |
| Furcation involvement | None or Class I | Class II or III, especially maxillary molars with close root proximity or a short root trunk |
| Mobility | Physiologic | Miller Class II–III, especially increasing over time |
| Restorability | Sound supragingival tooth structure with a ferrule of at least 1.5–2 mm circumferentially | Subgingival margins violating biologic width (roughly 2 mm of connective tissue and epithelial attachment), inadequate ferrule |
| Root anatomy | Long, divergent, broad roots | Short, tapered, fused roots; deep developmental grooves |
| Endodontic status | Well obturated, no lesion, restorable | Perforation, vertical root fracture, non-negotiable canals, persistent lesion after retreatment |
| Caries | Accessible, restorable | Deep subgingival, furcation caries, circumferential root caries |
| Strategic value | Terminal abutment, only opposing occlusal contact | Third molar, tooth with an easily restored alternative |
Vertical root fracture is a hopeless finding. Its signature is an isolated, narrow, deep probing defect on an otherwise periodontally healthy tooth, often with a J-shaped or halo radiolucency and a sinus tract near the gingival margin.
Patient-Level Prognostic Factors
These modify every tooth simultaneously, which is why the overall prognosis can be worse than the best individual tooth prognosis.
- Smoking — the strongest modifiable risk factor for periodontal and implant failure. Smokers respond less well to both non-surgical and surgical periodontal therapy, and implant failure rates are substantially higher.
- Diabetes control — poorly controlled diabetes impairs healing and increases periodontal breakdown; well-controlled diabetes approaches a normal response.
- Oral hygiene and adherence — the single best predictor of long-term outcome. A technically excellent plan delivered to a non-adherent patient fails.
- Parafunction — bruxism transmits destructive lateral loads to restorations, implants, and periodontally compromised teeth.
- Caries risk — high caries activity threatens margins on every restoration placed.
- Xerostomia, immunosuppression, prior head and neck radiation, and antiresorptive therapy all reduce prognosis and change what can safely be done.
- Economic and access constraints — a plan the patient cannot complete or maintain has a poor prognosis regardless of biology.
Structuring the Presentation of Alternatives
For each problem, present a structured set of options. Every set must include the no-treatment option and its expected consequences.
Example: a maxillary first molar with a Class II buccal furcation, 60% bone loss, and a fractured mesiobuccal cusp.
| Option | What it involves | Prognosis | Cost/time | Risks |
|---|---|---|---|---|
| No treatment | Monitor; accept progression | Poor to hopeless; likely abscess or spontaneous loss | None now; higher later | Pain, infection, additional bone loss complicating future implant |
| Periodontal therapy plus crown | Scaling and root planing, furcation debridement, possible surgery, crown lengthening if needed, then crown | Questionable | Moderate–high, multiple visits | May still fail; crown lengthening reduces support further |
| Root resection or hemisection plus crown | Remove the compromised root, endodontics, restoration | Fair in selected cases | High, technique sensitive | Root fracture of the remaining root; requires excellent hygiene |
| Extraction and implant | Extraction, possible graft, implant, crown | Good if smoking and diabetes are controlled | High, 4–8 months | Sinus proximity, surgical risk, cost |
| Extraction and fixed partial denture | Prepare adjacent teeth | Fair; depends on abutment health | Moderate–high | Sacrifices sound tooth structure on abutments |
| Extraction alone or removable partial denture | Restore function removably | Fair | Lowest | Reduced function; abutment caries risk |
Sequencing principles that shape the recommendation
- Control disease before rebuilding. Caries and periodontal inflammation are stabilized before definitive prosthetics — restorations placed onto active disease inherit its prognosis.
- Do not build a fixed prosthesis on a questionable abutment. A three-unit bridge with one questionable abutment converts a single-tooth risk into a three-unit failure and often costs the second abutment as well.
- Preserve future options. Extraction with socket preservation retains the implant option; aggressive over-preparation of virgin teeth for a bridge does not.
- Match the plan to demonstrated adherence. Escalating complexity for a patient who has not yet demonstrated hygiene control is a predictable failure.
Communicating Prognosis Honestly
- Use plain language and specific probabilities where they exist. "About one in ten of these crowns needs a root canal within ten years" is more useful than "there is a small risk."
- Distinguish what is known from what is uncertain. "Questionable" means the outcome genuinely cannot be predicted, and saying so is more honest than an optimistic guess.
- State the maintenance requirement as part of the prognosis, because it is: implants and periodontally treated teeth require ongoing professional maintenance to achieve the quoted survival rates.
- Document the alternatives discussed, the patient's questions, and the choice made.
- Where the patient declines the recommended option, record the recommendation, the refusal, and the consequences explained — an informed refusal.
A test-worthy distinction: survival means the restoration or implant is still in the mouth; success means it is functioning without complications. Quoting a 95% ten-year implant survival rate without mentioning peri-implant disease rates overstates the outcome the patient is buying.
A maxillary second premolar has an isolated 10 mm probing depth on the mid-buccal, while every other site on the tooth probes 3 mm. The tooth was endodontically treated four years ago and has a post and crown, and there is a sinus tract near the gingival margin. What is the most likely diagnosis and prognosis?
Which patient-level factor most strongly reduces both periodontal therapy outcomes and dental implant survival?
A patient needs a replacement for a missing mandibular first molar. The second premolar is a questionable abutment with 50 percent bone loss and Class I mobility. Which consideration should most influence the recommendation?
When presenting treatment alternatives, which element must always be included?