Diagnosis: Patient Evaluation, Imaging, and Risk Stratification
Framework
Diagnosis in implant dentistry is a cumulative process: medical history, extraoral and intraoral examination, periodontal assessment, occlusal analysis, and imaging. Each finding must be translated into a risk category (low, moderate, high) that drives the treatment plan. Candidates should be fluent with absolute and relative contraindications, the role of HbA1c in diabetic patients (generally <7% considered acceptable, with poor control raising infection and failure risk), smoking dose-response, and head-and-neck radiation history (osteoradionecrosis risk, timing and hyperbaric oxygen controversies).
Imaging and anatomy
Understand the diagnostic hierarchy: periapical and panoramic films for gross assessment, CBCT for bone volume, ridge width, sinus proximity, and nerve canal location. Know the anatomic danger zones: inferior alveolar canal and mental foramen, lingual concavity in the posterior mandible, nasopalatine canal, and maxillary sinus septa. Bone density classification (Lekholm and Zarb) and ridge defect classification (Cawood and Howell) are commonly tested.
Traps
Questions often blur screening versus definitive diagnosis, or present a normal panoramic film as sufficient when CBCT is indicated (e.g., posterior maxilla, nerve proximity). Another trap: attributing implant failure to poor hygiene when uncontrolled systemic disease or parafunction is the real driver. Watch for distractors that ignore occlusal risk (bruxism) or periodontal stability.
Rule of thumb
If a proposed implant site is within 2 mm of a critical structure or the ridge width is uncertain on a 2D film, obtain a CBCT. Example: a 62-year-old with well-controlled type 2 diabetes (HbA1c 6.8%), a 6-mm posterior mandibular ridge, and a mental foramen visible on panoramic - CBCT is still indicated to measure canal position and ridge width before selecting implant diameter.
Key concepts
Risk stratification, medical clearance, CBCT indications, anatomic danger zones, bone quality/quantity classification, occlusal and periodontal risk.