Pediatric and Preventive Dentistry: Fluorides, Space and Trauma
Pediatric and Preventive Dentistry
This domain tests early childhood caries, fluoride vehicles and their concentrations, pulp therapy in primary teeth, space maintenance, behaviour guidance and paediatric trauma.
Core rules
- Early childhood caries affects children up to 71 months, typically maxillary incisors first with mandibular incisors spared because of salivary protection.
- Fluoride concentrations: 5% sodium fluoride varnish about 22,600 ppm F applied every 3–6 months; 1.23% APF about 12,300 ppm; 0.05% NaF daily rinse about 225 ppm; 0.2% weekly rinse about 900 ppm; 38% silver diamine fluoride about 44,800 ppm.
- Pulpotomy options in primary molars include formocresol (effective but pharmacologically controversial), ferric sulfate and MTA; pulpectomy uses a resorbable paste such as zinc oxide eugenol or iodoform-based material.
- Space maintainers - band and loop, Nance appliance, lingual arch - are placed after premature loss, with greatest space loss following early loss of a primary second molar before first permanent molar eruption.
- Frankl scale rates behaviour 1 (definitely negative) to 4 (definitely positive); a dental home should be established by 12 months.
Worked example
What is the fluoride concentration of a 0.05% sodium fluoride daily mouthrinse? 0.05% means 0.05 g per 100 mL, or 500 mg NaF per litre. Fluoride is 19/42 of the NaF molecule, so 500 × 19/42 ≈ 225 mg/L, which is 225 ppm F. If a parent asks whether this is safe for a five-year-old, the arithmetic matters: 225 ppm is roughly 1% of varnish concentration, so it is a low-dose, high-frequency vehicle but still contraindicated in a child who cannot reliably spit.
Traps
- Quoting percentage without converting to ppm - examiners test the conversion.
- Replanting an avulsed primary tooth (never replant primary teeth).
- Removing an intruded primary incisor immediately when it is not displaced toward the permanent germ.
- Prescribing fluoride supplements without assessing water fluoride level.