Orthodontics and Dentofacial Orthopedics
Orthodontics and Dentofacial Orthopedics tests growth, cephalometrics, malocclusion classification, appliance mechanics, and treatment timing. Questions often combine a skeletal pattern with a treatment choice.
Core rules
- Class I molar relationship has the mesiobuccal cusp of the maxillary first molar in the buccal groove of the mandibular first molar.
- Class II division 1 has increased overjet and proclined maxillary incisors; division 2 has retroclined central incisors.
- ANB angle indicates skeletal jaw relationship: increased ANB suggests Class II skeletal pattern; negative ANB suggests Class III.
- Leeway space is larger in the mandible and can be used for crowding relief.
- Functional appliances are most effective during growth; fixed appliances can move teeth but cannot modify skeletal growth substantially in adults.
Worked example
A 10-year-old has a convex profile, increased overjet, and Class II molar relationship with proclined upper incisors. Cephalometrics shows increased ANB. The diagnosis is skeletal Class II with Class II division 1 dental features. Because the patient is growing, a functional appliance can restrain maxillary growth and posture the mandible forward; adult treatment would rely more on camouflage or surgery.
Traps
- Do not classify malocclusion from overjet alone; check molar and canine relationships.
- ANB depends on landmark placement and age; it is not the only skeletal indicator.
- Early loss of primary molars can cause space loss, not automatically more space.
- Expansion in adults is limited by sutural fusion.