Orthodontics and Dentofacial Orthopedics
This domain tests growth and development, orthodontic diagnosis, appliance principles, treatment timing and retention. The exam favours cases where growth status changes the treatment choice.
Diagnosis and growth
- Use study models, photographs, cephalometrics and panoramic radiographs. Assess skeletal pattern, dental relationships, crowding, overjet, overbite and path of eruption.
- Maxillary growth is forward and downward; mandibular growth includes condylar growth and remodelling. Growth prediction is imperfect, so timing matters.
Treatment principles
- Removable appliances can tip teeth and expand arches; fixed appliances provide three-dimensional control. Functional appliances modify growth or posture in selected Class II cases.
- Anchorage controls unwanted tooth movement. Extraction decisions require space analysis, profile assessment and treatment goals.
- Retention is part of treatment; relapse is common without retainers.
Worked example
A 12-year-old has a Class II division 1 malocclusion, 9 mm overjet and mandibular retrognathia, and is still growing. Reasoning: the increased overjet and growth status make a functional appliance such as a Twin Block reasonable to posture the mandible and reduce overjet. In a non-growing adult, camouflage or surgery may be more appropriate.
Traps that cost marks
Do not extract teeth without space analysis and a clear plan. Do not treat impacted canines by simple extraction without imaging. Growth timing changes the choice between functional and fixed appliances. Poor compliance ruins removable appliance treatment. Retention is not optional.