Orthodontics and Periodontics / Restorative Interrelationships
What the exam tests
How tooth movement interacts with periodontal attachment and restorative needs, and how to sequence interdisciplinary care.
Core rules
- Biologic width ≈2.04 mm (junctional epithelium plus connective tissue attachment); intrusion can encroach on it and cause recession or pocketing.
- Thin gingival biotype, dehiscence, and fenestration increase recession risk during expansion, intrusion, and labial movement.
- Orthodontic forces are generally safe with controlled periodontitis; inflammation must be controlled before and during treatment.
- Forced eruption extrudes and moves the attachment, improving crown length and bone contours for restorations.
- Corticotomy and PAOO can accelerate movement and augment bone in selected cases.
- Uprighting molars and developing implant sites require space analysis and coordination with the restorative plan.
- TADs must be placed with root and nerve safety margins.
Worked example
A 38-year-old with 4 mm lower crowding, 1 mm attached gingiva, and a thin biotype. Reasoning: rapid labial expansion risks recession; consider IPR, lingual mechanics, or a gingival graft before significant movement, and limit expansion. Document the periodontal risk in consent.
Traps
- Expanding or intruding aggressively in a thin biotype.
- Starting orthodontics with active periodontitis.
- Ignoring biologic width in intrusion cases.
- Planning tooth movement without the restorative endpoint.