Paediatric and preventive dentistry

In short

Paediatric dentistry (pedodontics) is the specialty that delivers comprehensive oral care from birth through adolescence, including the medically compromised and differently abled child, while preventive dentistry covers the fluoride, sealant, diet and plaque-control measures that stop disease before it needs a drill. The two are taught and examined together because the primary dentition is thin-enamelled, large-pulped and short-lived, so prevention and timely minimal intervention matter more than complex restoration. It is a full final-year BDS paper with a clinical/viva component under the National Dental Commission (NDC, which replaced the Dental Council of India) curriculum, and is heavily asked in MDS entrance exams (NEET MDS), NBE/INI-CET style MCQs and in interviews at dental chains and hospitals. Employers — Clove Dental, Apollo White, FMS, Sabka Dentist, government CHC/district hospitals, school-health and Ayushman Bharat oral-health programmes — test it because paediatric and preventive work is the volume end of Indian practice. Public-health content (indices, fluoride levels, National Oral Health Programme) sits here too.

Explained

Growth of the dentition, eruption and chronology

• Primary dentition: 20 teeth (2-1-0-2 per quadrant: central incisor, lateral incisor, canine, two molars). No premolars. Eruption roughly 6-30 months; mandibular central incisor first (~6-8 months), second primary molar last (~24-30 months).
• Useful rule: at ~6, 12, 18, 24 months a child has approximately 4, 8, 12, 16 teeth; complete by 2½-3 years. Root completion ≈ 1-1½ years after eruption; root resorption begins ~3 years before exfoliation.
• Permanent dentition: 32 teeth. First to erupt is the mandibular first molar or central incisor (~6 years); second molar ~12 years; third molar 17-21 years. Mandibular teeth generally precede maxillary; girls slightly earlier.
• Mixed dentition ≈ 6-12 years. Ugly duckling stage (Broadbent) — flared, spaced upper incisors at 8-9 years from canine crowns pressing the roots; self-correcting, no treatment.
• Physiological spacing and primate space (distal to mandibular canine, mesial to maxillary canine) are normal and desirable; crowding in the primary dentition predicts crowding later.
• Leeway space of Nance: primary canine + molars are wider than the succeeding permanent canine + premolars — about 1.8 mm per side in the mandible, 0.9 mm in the maxilla; it absorbs incisor liability.
• Terminal plane relation of distal surfaces of second primary molars: flush (most common in Indians), mesial step, distal step. Flush terminal plane → Class I only if late mesial shift uses leeway space.
• Nolla's stages (1-10) of tooth calcification and Demirjian's stages (A-H) are used for dental age estimation; eruption/calcification tables are examined for forensic age estimation under the JJ Act context.

Morphology of primary teeth and why management differs

• Thinner enamel and dentine (~1 mm each), so caries reaches the pulp fast; large pulp chamber with high mesial pulp horn.
• Broad, flat interproximal contacts; cervical constriction and prominent cervical ridge; crown bulbous, roots slender, flared and divergent (to house the succeeding tooth bud).
• Enamel rods at the cervix slope occlusally, so no cervical bevel is given in cavity preparation.
• Shorter clinical crown, whiter and more opaque; pulp is more vascular and reparative, but also more likely to respond with internal resorption.
• Consequences: shallower preparations, no deep boxes, pulp therapy rather than deep dentine excavation, preformed crowns rather than large multi-surface amalgams, and rubber dam/short appointments for behaviour.

Caries in children: ECC, diagnosis, indices

• Early childhood caries (ECC): one or more decayed (cavitated/non-cavitated), missing (due to caries) or filled surfaces in any primary tooth in a child under 6 years (AAPD). Severe ECC (S-ECC): any smooth-surface caries under 3 years; or in 3-5 year-olds, dmfs ≥4 (age 3), ≥5 (4), ≥6 (5), or any cavitated/filled/missing maxillary anterior surface.
• Nursing/bottle caries pattern: maxillary incisors labially and palatally, then first molars; mandibular incisors spared by tongue and submandibular saliva. Cause: on-demand bottle/breastfeeding at night, sweetened pacifiers.
• Rampant caries (Massler): sudden, rapid, involving surfaces usually immune, including lower anteriors — older children, frequent sucrose.
• Aetiology triad plus time: cariogenic bacteria (*Streptococcus mutans*, *Lactobacillus*), fermentable carbohydrate, susceptible tooth, time. Critical pH ~5.5 for enamel, ~6.2-6.7 for root dentine. Stephan curve — pH drops within 2-5 min of sugar, recovers in 20-40 min; frequency of sugar matters more than amount.
• Indices: dmft/dmfs (Gruebbel, primary, lower case), DMFT/DMFS (Klein, Palmer & Knutson, permanent), deft/def where missing teeth are unreliable (exfoliation). ICDAS II codes 0-6 for non-cavitated to extensive lesions. SiC index (Significant Caries Index) = mean DMFT of the worst third of the population.
• Risk assessment tools: Caries Risk Assessment Tool (CAT/CRA) and Cariogram; risk grouped low/moderate/high from caries experience, plaque, diet frequency, fluoride exposure, saliva and special health care needs.
• Caries activity tests (examined, rarely used clinically): Snyder test, Lactobacillus colony count, *S. mutans* count (Dentocult SM), Swab test, salivary buffer capacity.

Preventive dentistry: fluorides, sealants, diet, plaque control

• Levels of prevention (Leavell & Clark): primary (health promotion, specific protection — fluoride, sealants), secondary (early diagnosis and treatment — restoration), tertiary (rehabilitation — prosthesis). Primordial prevention = preventing risk factors arising at all.
• Fluoride mechanism: forms fluorapatite (less soluble), promotes remineralisation of white spots, inhibits bacterial enolase and glycolysis. Pre-eruptive systemic benefit is small; topical post-eruptive action dominates.
• Systemic fluoride: water fluoridation optimum ~0.7 ppm in warm climates (India); the BIS drinking-water standard IS 10500 sets fluoride at 1.0 mg/L acceptable and 1.5 mg/L permissible. Fluoride tablets/drops are not recommended in India because much of the country is endemic for fluorosis (parts of Rajasthan, Gujarat, Andhra Pradesh/Telangana, Karnataka, Tamil Nadu, Bihar, Jharkhand, UP, Haryana, Punjab, Odisha, MP, Assam, WB, Maharashtra, Chhattisgarh — commonly cited as about 20 states/230 districts; counts vary by survey, so quote with the source).
• Topical fluoride, professional: 5% sodium fluoride varnish (22,600 ppm F) — safest for under-6s, 2-4 applications/year in high risk; 2% NaF solution (9,040 ppm, Knutson technique, 4 weekly visits); 8% SnF₂ (stains, unstable); 1.23% APF gel (12,300 ppm, pH 3.5, 4 min tray, not for porcelain/composite restorations); fluoride-releasing GIC.
• Topical fluoride, home: toothpaste — smear (~0.1 mg F) under 3 years, pea-sized (~0.25 mg) 3-6 years, 1,000-1,450 ppm; 0.05% NaF daily or 0.2% NaF weekly mouthrinse only after 6 years (swallowing risk). 5,000 ppm paste for adolescents at high risk.
• Silver diamine fluoride (SDF) 38%: arrests dentine caries 1-2 ×/year, non-restorative; stains the lesion black; valuable for uncooperative children, special-needs patients and camp settings. Consent for staining is mandatory.
• Pit and fissure sealants: resin-based (preferred, retentive but needs dry field) or GIC (fluoride-releasing, used as an interim/partially erupted tooth). Steps: clean → isolate → etch 37% phosphoric acid 15-30 s (20-30 s primary: longer, 60 s often advised) → rinse, dry, verify frosty enamel → apply → cure 20-40 s → check occlusion and retention. Indicated for deep retentive fissures, high-risk children, newly erupted first and second permanent molars.
• Preventive resin restoration (PRR): minimal enamel/dentine caries excavated, restored with composite and the rest of the fissure system sealed.
• ART (atraumatic restorative treatment): hand excavation with spoon excavators/hatchets, no rotary instruments, restoration with high-viscosity GIC and finger pressure — WHO-endorsed for field, school and camp use in India.
• Diet counselling: 5-day diet diary, score sugar frequency, substitute with non-cariogenic foods; xylitol chewing gum (bacterial non-fermentation), sorbitol less effective. Cheese, milk and peanuts are protective (phosphopeptides, raise pH).
• Plaque control in children: parental brushing until ~8 years; horizontal scrub, or the Fones circular technique, for small children; chlorhexidine 0.2% only for short-term and special needs; supervised school brushing programmes.
• Fluoride toxicity: Certainly Lethal Dose ~32-64 mg F/kg; Safely Tolerated Dose ~8-16 mg F/kg (one-quarter of CLD); Probably Toxic Dose ~5 mg F/kg. Management: <5 mg/kg — milk orally; >5 mg/kg — induce vomiting, milk/calcium (milk of magnesia, calcium gluconate), hospital; >15 mg/kg — emergency, IV calcium gluconate, cardiac monitoring.
• Chronic fluorosis: Dean's index (normal, questionable, very mild, mild, moderate, severe); Thylstrup-Fejerskov (TFI) 0-9; treatment — microabrasion, bleaching, composite/veneer, and at source, defluoridation (Nalgonda technique using alum + lime + bleaching powder, developed at NEERI, Nagpur; activated alumina; reverse osmosis). Skeletal fluorosis is addressed by the National Programme for Prevention and Control of Fluorosis (NPPCF).

Restorative and pulp therapy in the primary dentition

• Restorative materials: GIC/RMGIC (fluoride release, chemical bond, class I/V and ART), composite with strip crowns for anteriors, compomer, and amalgam (declining; India signed the Minamata Convention on Mercury, and amalgam use in children under 15 and in pregnant/nursing women is discouraged under it).
• Stainless steel crown (SSC/Humphrey crown): indicated after pulp therapy, in multi-surface caries, hypoplastic/amelogenesis-imperfecta teeth, as a space-maintainer abutment and in bruxing or high-risk children. Longest-lasting restoration for primary molars. Hall technique — no caries removal, no local anaesthesia, SSC seated with GIC luting cement over the sealed lesion; strong evidence base, now mainstream.
• Indirect pulp capping: deep lesion, no pulpitis — leave affected dentine, place calcium hydroxide/RMGIC, restore.
• Direct pulp capping: only for a small (<1 mm) mechanical/iatrogenic exposure in a non-carious asymptomatic primary tooth; MTA or Biodentine preferred; carious exposure in a primary tooth is a contraindication (internal resorption risk).
• Pulpotomy (removal of coronal pulp, vital radicular pulp retained): indicated in a vital carious exposure with reversible pulpitis, no radiolucency, no mobility. Medicaments — MTA (highest success), Biodentine, ferric sulphate 15.5% (Smith technique), formocresol (Buckley's diluted 1:5, Sweet's technique — carcinogenicity concerns, falling out of use), electrosurgical/laser. Restore with SSC.
• Pulpectomy (complete pulp removal and canal filling): irreversible pulpitis or necrosis with restorable crown. Obturating materials must resorb with the tooth — ZOE, iodoform pastes (KRI), calcium hydroxide + iodoform (Vitapex, Metapex), Endoflas. Gutta-percha is NOT used in primary teeth.
• Apexogenesis — vital pulp therapy in an immature permanent tooth to let the root complete and apex close. Apexification — inducing an apical barrier in a necrotic immature tooth: calcium hydroxide (multiple visits) or a single-visit MTA apical plug; regenerative endodontics/revascularisation using a blood clot scaffold is the modern alternative.
• Extraction indications: unrestorable tooth, abscess with bone loss, over-retained tooth, pre-orthodontic serial extraction.

Space management, habits and interceptive care

• Space loss follows early loss of a primary tooth — fastest in the first 6 months after loss, worse in the maxilla and in the molar region.
• Space maintainers: removable (acrylic partial denture) vs fixed; non-functional vs functional; active vs passive. Types — band-and-loop (single tooth loss, erupted permanent first molar), crown-and-loop, lingual arch (bilateral mandibular loss, after lower incisors erupt), Nance palatal arch / transpalatal arch (maxilla), distal shoe (Willett appliance) for loss of the second primary molar before the permanent first molar erupts, removable partial denture for multiple losses and aesthetics.
• Space regainers when space is already lost — e.g. removable split saddle, Gerber, Hotz lingual arch.
• Serial extraction (Kjellgren/Hotz): C → D → 4 sequence in severe arch-length deficiency; needs a Class I molar relation and no skeletal discrepancy.
• Oral habits: thumb/digit sucking (proclined upper incisors, anterior open bite, posterior crossbite, high palatal vault, hyperactive mentalis), tongue thrusting, mouth breathing (adenoid facies, long face, gummy smile), nail biting, bruxism, lip biting. Management ladder — counselling → reminder therapy (bitter preparations, bandage, thumb guard) → mechanical appliance (palatal crib, oral screen, Bluegrass, quad helix); appliances only after ~4-5 years and with the child's consent and motivation.
• Interceptive measures: anterior crossbite correction with an inclined plane/catlan appliance, posterior crossbite expansion, frenectomy for a diastema-causing frenum after canine eruption.

Behaviour management, local anaesthesia and dental trauma

• Child psychology: development theories examined — Freud (psychosexual), Erikson (psychosocial), Piaget (cognitive: sensorimotor 0-2, preoperational 2-7, concrete operational 7-11, formal operational 11+), Bandura (social learning).
• Fear/anxiety rating: Frankl behaviour rating scale — Rating 1 definitely negative (− −), 2 negative (−), 3 positive (+), 4 definitely positive (+ +). Also Wright's classification (cooperative, lacking cooperative ability, potentially cooperative), Venham picture test, Corah's Dental Anxiety Scale, CFSS-DS.
• Non-pharmacological: tell-show-do (Addelston), voice control, positive reinforcement, distraction, modelling, desensitisation, HOME (hand-over-mouth — now largely abandoned and not permitted without specific consent; many bodies have removed it), protective stabilisation only with informed written consent and a documented justification.
• Pharmacological: nitrous oxide-oxygen inhalation sedation (N₂O 30-50%, titrated), oral/IV sedation, general anaesthesia for extensive treatment, very young or special-needs children — requires anaesthetist, fasting protocol and written consent.
• Local anaesthesia: 2% lignocaine with 1:80,000 adrenaline; maximum lignocaine dose 4.4 mg/kg (commonly cited 4.4-7 mg/kg with vasoconstrictor), absolute maximum ~300 mg; one 2 mL cartridge of 2% = 40 mg. Articaine 4% gives good buccal infiltration anaesthesia of mandibular primary molars. Topical benzocaine/lignocaine before injection; techniques — infiltration, inferior alveolar nerve block (mandibular foramen lies below the occlusal plane in young children), intrapapillary, intraligamentary. Avoid prilocaine in methaemoglobinaemia risk; watch self-inflicted lip/cheek bite after a block — warn the parent.
• Trauma (Andreasen/Ellis classification): enamel infraction; enamel fracture; enamel-dentine fracture; with pulp exposure; crown-root fracture; root fracture; concussion; subluxation; lateral luxation; intrusion; extrusion; avulsion.
• Avulsion of a permanent tooth: replant immediately; best storage media — HBSS (Save-A-Tooth) > cold milk > saliva > normal saline; hold the crown, do not scrub the root; extra-oral dry time >60 min = poor prognosis; splint 2 weeks (avulsion), antibiotics, tetanus review, root canal treatment 7-10 days after. An avulsed primary tooth is NEVER replanted (risk to the permanent successor).
• Prevention of trauma: custom-fitted mouthguards (and the Indian context of cricket, kabaddi and contact sport), face shields; anticipatory guidance for toddlers.
• Child abuse: two-thirds of physical abuse injuries involve the head, face and mouth; reporting a suspected case to the Child Welfare Committee/police is a legal duty under the POCSO Act, 2012 for sexual offences and the Juvenile Justice (Care and Protection of Children) Act, 2015 generally.
• Developmental anomalies examined here: natal/neonatal teeth (and Riga-Fede disease), Epstein pearls/Bohn's nodules, eruption cyst, teething, amelogenesis and dentinogenesis imperfecta, hypoplasia (Turner's tooth from a periapical infection of the predecessor), molar incisor hypomineralisation (MIH), talon cusp, dens evaginatus/invaginatus, mulberry molars/Hutchinson incisors in congenital syphilis, anodontia in ectodermal dysplasia, papillon-Lefèvre (early periodontal destruction).

Key points

• Primary dentition - 20 teeth, no premolars, 2-1-0-2 per quadrant; first eruption ~6-8 months (lower central incisor), complete by ~30 months.
• Mixed dentition - 6-12 years; permanent first molar and lower central incisor erupt first at ~6 years.
• Leeway space - 1.8 mm per side mandibular, 0.9 mm maxillary; absorbs incisor liability and allows late mesial shift.
• Primary tooth morphology - thin enamel/dentine, large pulp with high mesial horn, flat broad contacts, cervical constriction, divergent roots; hence no cervical bevel and shallow preparations.
• ECC - any d/m/f surface in a primary tooth under 6 years; maxillary incisors first, mandibular incisors spared in bottle caries.
• Critical pH 5.5 - below it enamel demineralises; the Stephan curve shows frequency of sugar is the dominant factor.
• dmft vs DMFT - lower case for primary (Gruebbel), upper case for permanent (Klein & Palmer); deft used when exfoliation confounds "missing"; SiC index highlights the worst-affected third.
• Fluoride varnish 5% NaF - 22,600 ppm F, safest topical for under-6s, 2-4 times a year in high-risk children.
• Optimum water fluoride ~0.7 ppm in India; IS 10500 permits up to 1.5 mg/L; systemic fluoride supplements are inappropriate in an endemic-fluorosis country.
• Fluoride toxicity - PTD ~5 mg F/kg, STD 8-16 mg/kg, CLD 32-64 mg/kg; give milk/calcium and refer.
• Sealant - resin over retentive fissures of newly erupted molars; GIC as an interim when isolation is impossible; PRR when minimal caries exists.
• ART and SDF - rotary-free, field-friendly caries management; SDF 38% arrests dentine caries but stains it black (consent needed).
• SSC and the Hall technique - most durable primary-molar restoration; the Hall technique needs no caries removal, no anaesthesia and no tooth preparation.
• Pulpotomy vs pulpectomy - vital radicular pulp retained vs whole pulp removed; obturate primary canals with resorbable ZOE/iodoform/Ca(OH)₂-iodoform, never gutta-percha.
• Apexogenesis vs apexification - vital pulp allowed to finish root growth vs an apical barrier created (MTA plug) in a necrotic immature tooth.
• Distal shoe - the only space maintainer for loss of the second primary molar before the permanent first molar erupts; contraindicated in bacteraemia-risk or immunocompromised children.
• Frankl scale - 1 definitely negative to 4 definitely positive; the standard pre-treatment behaviour record.
• Avulsion - permanent tooth replanted at once (HBSS > milk > saliva), dry time over 60 min is a poor prognosis; a primary tooth is never replanted.

Formulas and examples

Example 1 - dmft and population indices. A school survey in Kochi examines 150 children aged 5. Findings: 60 children caries-free; the remaining 90 have a total of 312 decayed, 18 missing (caries) and 30 filled primary teeth.

• Total dmft = 312 + 18 + 30 = 360.
• Mean dmft = 360 ÷ 150 = 2.40.
• Prevalence = (90 ÷ 150) × 100 = 60%; caries-free = 40%.
• Mean dmft among the affected only = 360 ÷ 90 = 4.0.
• Care Index = (30 ÷ 360) × 100 = 8.33% — i.e. over 91% of the disease is untreated, the typical Indian picture.
• Interpretation: WHO/India surveys classify mean dmft/DMFT bands; 2.40 falls in the "low" band (WHO 1.2-2.6), and the very low care index, not the dmft, is the public-health message.

Example 2 - fluoride ion content and a varnish dose.

• 2% NaF solution: F% = 2 × 0.452 = 0.904% → 0.904 g F per 100 mL = 9,040 ppm F. Matches the textbook figure.
• 5% NaF varnish: 5 × 0.452 = 2.26% → 22,600 ppm F.
• A 0.25 mL dose of 5% NaF varnish (unit dose for a child): mass ≈ 0.25 g; F delivered = 22,600 × 0.25 ÷ 1,000 = 5.65 mg F.
• For a 15 kg four-year-old, PTD = 5 × 15 = 75 mg F — the varnish dose (5.65 mg) is 7.5% of PTD, hence its safety even if some is swallowed.

Example 3 - toothpaste swallowing and toxicity decision. A 3-year-old weighing 14 kg swallows 20 g of a 1,000 ppm F toothpaste.

• F ingested = 1,000 × 20 ÷ 1,000 = 20 mg F.
• Dose = 20 ÷ 14 = 1.43 mg F/kg — below PTD (5 mg/kg).
• Action: give milk or a calcium-containing drink orally, observe at home for nausea/vomiting; no hospital referral needed. Had the child swallowed a full 100 g tube: 100 mg F → 100 ÷ 14 = 7.14 mg F/kg > PTD → induce vomiting, give milk/milk of magnesia, refer to hospital.
• Contrast the daily pea-sized dose: 0.25 g of 1,000 ppm = 0.25 mg F — about 1/300th of this child's PTD.

Example 4 - local anaesthetic limit for a child. A 20 kg six-year-old needs an inferior alveolar block and two infiltrations, using 2% lignocaine with 1:80,000 adrenaline.

• Max dose = 4.4 × 20 = 88 mg lignocaine (below the 300 mg absolute cap, so 88 mg governs).
• Each 2 mL cartridge = 2 × 10 × 2 = 40 mg → maximum 88 ÷ 40 = 2.2 cartridges, so safely 2 cartridges (80 mg).
• Adrenaline in 2 cartridges = 2 × 25 = 50 µg — well within the 0.2 mg (200 µg) ceiling commonly taught for a healthy patient (0.04 mg for cardiac patients); not a limiting factor here.
• Practical plan: 1 cartridge for the block (1.8-2.0 mL), the remainder split between the two infiltrations.

Example 5 - space analysis with leeway space. Mixed-dentition analysis in a 9-year-old: available arch space in the lower left quadrant from the distal of the lateral incisor to the mesial of the first permanent molar = 20.5 mm; Moyers' table (75th percentile) predicts the combined 3-4-5 width = 22.0 mm.

• Space deficiency = 22.0 − 20.5 = 1.5 mm per side (3.0 mm per arch).
• Mandibular leeway space available = 1.8 mm per side, so the deficiency can be absorbed if the primary molars are preserved to term.
• Management: preventive, not extractive — maintain the Es, restore proximal caries to retain tooth width, monitor; serial extraction is reserved for deficiencies of roughly 4-5 mm or more per side with a Class I skeletal pattern.

Where it is used

• Private paediatric and family dental practice: ECC management, SSC/Hall technique, sealants and varnish recalls — the bread-and-butter of chains such as Clove Dental, Sabka Dentist, Apollo White, FMS and Partha Dental, where new graduates are tested on exactly these protocols.
• Government service and public health: oral-health components of Ayushman Bharat Health and Wellness Centres, the National Oral Health Programme, Rashtriya Bal Swasthya Karyakram (RBSK) child screening (dental conditions are among its listed deficiencies/diseases/disabilities), school dental screening, and NPPCF fluorosis districts; dental surgeons in CHCs/district hospitals and the ESIC/railway/defence dental services.
• Camp, school and rural programmes: ART with high-viscosity GIC, SDF arrest, supervised brushing and fluoride-varnish drives run by dental colleges' departments of public health dentistry (a compulsory rural service/internship posting in most states).
• Hospital and special-care dentistry: full-mouth rehabilitation under GA for very young, autistic, cerebral-palsy or cardiac children; pre-chemotherapy/pre-cardiac-surgery dental clearance in tertiary hospitals.
• Industry and product roles: dental product companies (3M, GC, Dentsply Sirona, Ivoclar, Prevest DenPro, Shofu India) employ dentists in training and technical roles for sealants, GIC, varnish, SSCs and paediatric crowns; dentifrice brands for formulation and claims support.
• Teaching, MDS and research: Pedodontics and Preventive Dentistry is one of the nine MDS specialities; tutor/senior-resident posts and trial work on SDF, Hall technique and MIH are active Indian research areas.

Interview questions

• Q: Why does caries reach the pulp faster in a primary tooth? A: Enamel and dentine are each only about 1 mm thick and the pulp chamber is proportionally large with a high mesial pulp horn, so the lesion has a very short distance to travel.
• Q: Which teeth are spared in nursing bottle caries and why? A: The mandibular incisors — the tongue covers them during sucking and submandibular/sublingual saliva flows over them, so they are protected.
• Q: What is the optimum fluoride level in drinking water for India, and why not higher? A: About 0.7 ppm, because in a warm climate water intake is higher; much of India is endemic for fluorosis, and IS 10500 permits only up to 1.5 mg/L.
• Q: A 4-year-old has rampant upper anterior caries and will not accept a drill. What do you do? A: Stabilise with SDF or ART/GIC and fluoride varnish, intensive diet and brushing counselling with the parent, then definitive care under sedation or GA if needed — after explaining the black staining of SDF and taking written consent.
• Q: Difference between pulpotomy and pulpectomy? A: Pulpotomy removes only the coronal pulp and keeps a vital radicular pulp; pulpectomy removes the entire pulp and fills the canals with a resorbable paste.
• Q: Why is gutta-percha not used in primary root canals? A: It does not resorb, so it would obstruct physiological root resorption and the eruption path of the permanent successor; resorbable ZOE or iodoform/Ca(OH)₂ pastes are used.
• Q: What is the Hall technique and what is the evidence? A: Cementing a stainless steel crown over a carious primary molar with GIC, without caries removal, tooth preparation or local anaesthesia; randomised trials show survival at least as good as conventional restorations, by sealing the lesion from substrate.
• Q: Would you replant an avulsed primary incisor? A: No — replanting a primary tooth risks damaging or displacing the developing permanent successor; reassure the parent, manage the socket and plan an aesthetic appliance if needed.
• Q: Maximum dose of 2% lignocaine with adrenaline for a 20 kg child, in cartridges? A: 4.4 mg/kg × 20 = 88 mg; one 2 mL cartridge holds 40 mg, so two cartridges (80 mg) is the safe working maximum.
• Q: When is a distal shoe appliance indicated, and when is it contraindicated? A: When the second primary molar is lost before the permanent first molar erupts, to guide its eruption; it is contraindicated where there is a bacteraemia or healing risk — cardiac disease, immunosuppression, poorly controlled diabetes, blood dyscrasias — and where parental cooperation is poor.
• Q: What is the Stephan curve and its practical lesson? A: The plot of plaque pH after a sugar challenge — it falls below the critical pH 5.5 within minutes and takes 20-40 minutes to recover, so reducing the frequency of sugar intake matters more than the quantity.
• Q: A child swallows a tube of toothpaste. How do you decide the urgency? A: Calculate mg F/kg: below 5 mg/kg give milk and observe; above 5 mg/kg induce vomiting, give milk or calcium and refer; above 15 mg/kg treat as an emergency with IV calcium and cardiac monitoring.
• Q: Why do you use GIC rather than resin for sealing a partially erupted molar? A: Resin needs a dry, etchable, fully erupted surface for retention; GIC tolerates moisture, bonds chemically and releases fluoride, so it serves as an interim sealant until full eruption.

Common mistakes

• Writing the primary dentition as 2-1-2-2 or including premolars — there are no primary premolars; the formula is 2-1-0-2, 20 teeth.
• Giving a cervical bevel or a deep retentive box in a primary cavity — the cervical enamel rods slope occlusally and the pulp horn is high, so this exposes the pulp or weakens the margin.
• Confusing dmft with DMFT case, or counting a primary tooth as "missing" when it has simply exfoliated (use deft/def instead).
• Quoting 1 ppm as India's optimum water fluoride and recommending fluoride tablets — the Indian figure is around 0.7 ppm and supplements are inappropriate in endemic fluorosis areas.
• Mixing up the fluoride toxicity figures (PTD 5 mg/kg, STD 8-16, CLD 32-64 mg F/kg) or forgetting to convert ppm to mg per actual gram ingested.
• Doing direct pulp capping on a carious exposure in a primary tooth, or a pulpotomy where there is already a furcation radiolucency, mobility or a sinus — those need pulpectomy or extraction.
• Replanting an avulsed primary tooth, scrubbing the root of a permanent one, or storing it in water or spirit instead of HBSS, cold milk or saliva.
• Treating the child without involving the parent in diet and brushing control — the restoration fails and the caries returns if the habit is untouched.

Related topics

Conservative dentistry: caries and restorations · Endodontics: root canal treatment · Orthodontics and dentofacial orthopaedics · Oral and maxillofacial surgery: extractions and minor oral surgery · Medical emergencies in the dental clinic · Public health dentistry and oral epidemiology