Orthodontics and Dentofacial Orthopedics
What the exam tests
Orthodontics and Dentofacial Orthopedics tests growth assessment, cephalometric interpretation, treatment timing, biomechanics, anchorage, and retention. Cases typically ask whether a problem is skeletal or dental and whether to treat now or later.
Core rules
- Classify by skeletal pattern (SNA, SNB, ANB) and dental relationship. ANB >4° suggests a Class II skeletal tendency; ANB <0° suggests Class III, but soft tissue and incisor inclination matter.
- Growth modification works best during active growth. Functional appliances can influence mandibular position and growth in selected Class II cases; headgear restrains maxillary growth; facemask protracts the maxilla in Class III.
- Space analysis determines whether extraction is needed. Consider crowding, incisor inclination, profile, anchorage, and Bolton discrepancies.
- Anchorage is the resistance to unwanted tooth movement. Plan it explicitly: palatal appliances, mini-screws, or segmental mechanics.
- Aligners require good patient compliance and careful attachment planning; complex movements may need fixed appliances.
- Retention is part of treatment: fixed retainers and/or removable retainers, with monitoring for relapse, root resorption, and decalcification.
Worked example
A 12-year-old has a Class II division 1 malocclusion, 10 mm overjet, ANB 6°, deep bite, and is still growing. The overjet is skeletal and dental. Because growth remains, a functional appliance phase can reduce overjet and improve mandibular position; definitive fixed appliances follow. If growth has ceased, camouflage with premolar extraction or orthognathic surgery must be discussed. Retention and airway assessment are planned from the start.
Traps
- Extracting premolars without an anchorage plan.
- Using cephalometric numbers without clinical soft tissue assessment.
- Treating a growing Class III with camouflage alone.
- Forgetting retention and consent for root resorption.