Orthodontic Diagnosis and Treatment Planning
What the exam tests
Building a prioritized problem list from history, extraoral and intraoral examination, models, and radiographs, then converting it into a defensible plan with alternatives and consent.
Core rules
- Record a problem list in priority order: function/airway, periodontal and caries risk, skeletal, dental, soft tissue/smile, patient expectations.
- Space analysis: arch length discrepancy, Bolton anterior (≈77.2%) and overall (≈91.3%) ratios, and leeway/E-space in mixed dentition.
- Assess the six keys of occlusion (molar relationship, crown angulation, crown inclination, rotations, contacts, curve of Spee).
- Transverse dimension is assessed clinically and on CBCT/models; a narrow maxilla with a functional shift will not be solved by alignment alone.
- Extraction decisions balance profile, crowding, anchorage, periodontal health, and the patient's own values.
- Always record growth status, compliance potential, and the consequences of no treatment.
Worked example
A 13-year-old girl, Class I molars, normal profile, 7 mm mandibular crowding, Bolton overall ratio 92.5% (mandibular excess). Reasoning: the profile and Class I molar relationship argue against mandibular incisor extraction, but the Bolton excess of ~1.2% means the upper arch cannot close spaces without maxillary spaces remaining. Option: non-extraction with distalization/IPR plus maxillary spacing closure, or extract a mandibular incisor if the overjet/overbite permits. Document both options and the effect on the profile.
Traps
- Treating cephalometric numbers instead of the patient and their chief complaint.
- Missing transverse deficiency and functional shift.
- Ignoring Bolton when planning extraction spaces.
- Presenting one plan without alternatives or risks.