Orthodontics and Pediatric Dentistry
What this domain tests
Items test growth assessment, Angle classification, cephalometric norms, treatment timing and appliance choice, plus behaviour management, caries prevention and dental trauma in children.
Orthodontics
- Angle classes: I neutroclusion, II distoclusion (division 1 proclined incisors, division 2 retroclined), III mesioclusion.
- Cephalometric means: SNA 82°, SNB 80°, ANB 2°; increased ANB suggests skeletal class II, reduced or negative suggests class III.
- Space analysis in the mixed dentition uses Moyer's or Tanaka-Johnston prediction; leeway space is about 1.5 mm per side in the mandible and 0.9 mm in the maxilla; primate spaces sit mesial to the maxillary canine and distal to the mandibular canine.
- Timing: intercept crossbites and displacement early; functional appliances (Twin Block, Herbst) work best during the pubertal growth spurt assessed by cervical vertebral maturation; skeletal class III may need protraction or later orthognathic surgery; aligners and temporary anchorage devices extend adult options. Retention is lifelong in principle.
Pediatric dentistry
- Behaviour guidance uses tell-show-do, positive reinforcement and the Frankl scale (definitely negative to definitely positive).
- Fluoride: toothpaste 1,000-1,500 ppm; varnish 22,600 ppm professionally; silver diamine fluoride arrests caries but stains black.
- Fissure sealants for deep pits on permanent molars; Hall technique stainless steel crowns for primary molars; pulpotomy with MTA or formocresol.
- Space maintenance: band and loop, Nance appliance, and a distal shoe when a primary second molar is lost before the first permanent molar erupts.
Worked example
A 9-year-old avulses a maxillary central incisor and arrives 40 minutes later with the tooth stored in milk. Reasoning: handle by the crown, rinse briefly, replant immediately if the socket is intact, and splint flexibly for 2 weeks. Check tetanus status; consider antibiotics; review pulpal status and expect pulp revascularisation or necrosis. If the tooth is out longer than 60 minutes with a closed apex, replantation prognosis falls sharply and ankylosis is likely, so storage medium and extraoral time drive the decision.
Traps
Using the Frankl scale backwards; confusing leeway and primate spaces; applying a rigid splint to an avulsed tooth; forgetting the distal shoe for an early lost second primary molar.