# Molar Incisor Hypomineralisation > Molar incisor hypomineralisation for BDS Operative Dentistry — demarcated opacities, post-eruptive breakdown, sensitivity, EAPD criteria and management. - Canonical URL: https://prepelephant.com/topics/bds/operative-dentistry/molar-incisor-hypomineralisation - Exam / course: BDS · Subject: Operative Dentistry - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Molar Incisor Hypomineralisation", PrepElephant, https://prepelephant.com/topics/bds/operative-dentistry/molar-incisor-hypomineralisation ## Direct answer Chalky-white and honey-brown demarcated opacities on freshly erupted first permanent molars define molar incisor hypomineralisation — a qualitative enamel defect of systemic origin, present in roughly 13 to 15 per cent of children in pooled global estimates, with Indian studies reporting wide variation. The defect is qualitative, not hypoplastic: enamel volume is formed but poorly mineralised, so it crumbles under ordinary chewing — post-eruptive breakdown — leaving "cheese-like" defects that harbour plaque, sensitise to air and cold, defeat anaesthesia surprisingly often, and bond poorly. Incisors carry opacities without breakdown. The European Academy of Paediatric Dentistry criteria (demarcated opacity, at least one first permanent molar affected, not explicable otherwise) standardise diagnosis, and management escalates from prevention and desensitising through adhesive restorations to preformed metal crowns or planned extraction with orthodontic input in the worst molars. ## What you must remember - **Definition:** hypomineralisation of systemic origin affecting one to four first permanent molars, frequently with incisor opacities, diagnosed by EAPD criteria — demarcated opacities, post-eruptive breakdown, atypical restorations or extractions unexplained by other disease. - **Prevalence:** pooled global estimates cluster around 13 to 14 per cent, with country and criteria variation from single digits to far higher — quote the range, not a single number. - **Aetiology:** unknown; implicated windows cluster around birth and the first three years — prematurity and low birth weight, febrile illnesses, hypoxia, antibiotics, dioxins and early childhood illness are associations, not proven causes. - **Clinical behaviour:** enamel chips under mastication ("cheese-like"), plaque and caries follow rapidly, sensitivity to air and cold is disproportionate, and local anaesthesia underperforms because of pulpal inflammation — behaviour management fails with repeated failed appointments. - **Severity grading:** mild (opacities, no breakdown), moderate (breakdown limited to one or two surfaces), severe (extensive breakdown, sensitivity preventing function) — the grading picks the treatment rung. - **Restorative difficulty:** etching hypomineralised enamel yields poor bond strengths and defective margins — excavation must reach sound enamel, or restorations shed. - **Escalating options:** fluoride varnish and CPP-ACP with diet control for mild cases; adhesive restorations (glass ionomer to composite) for moderate; preformed metal crowns or orthodontically-planned extraction of hopeless first molars for severe — timing extraction to the developing second molar improves space closure. ## Working through a seven-year-old's four molars A seven-year-old is brought for "brown soft teeth": all four first permanent molars have just erupted, each showing creamy-white demarcated opacities, and two have already chipped at the cusps after a few months of chewing. Grading: the two intact-molar pair is mild, the broken pair moderate-to-severe. The mild molars get prevention — fluoride varnish, CPP-ACP at home, dietary counselling and fissure protection, accepting that sealant retention on opaque enamel is unreliable and needs review. One broken molar is restored with composite after excavating to sound enamel; breakdown keeps outrunning restorations and each visit hurts. The worst molar, half destroyed and sensitive, goes to extraction timed with the orthodontist so the second premolar and second molar drift favourably. Incisor opacities are monitored — composite masking waits until the gingival margin stabilises and the child wants it. The case teaches the syndrome's central management truth: MIH is a lifelong condition requiring scheduled recall, not a one-visit restoration, and the treatment rung is chosen per molar, not per patient. ## How the exam frames MIH Papers set this as a short note on molar incisor hypomineralisation and expect the EAPD definition, prevalence with honest hedging, the post-eruptive breakdown phenomenon, and the staged management ladder. Viva examiners probe the qualitative-versus-quantitative distinction: hypomineralisation means defective mineralisation of formed enamel, whereas hypoplasia means deficient enamel volume — conflating them is the classic error. The second probe is why restorations fail: poorly mineralised enamel does not etch into a reliable tag pattern, so the answer must include excavating to sound enamel. The third is why these children cry at simple visits — sensitivity, disappointing anaesthesia, repeated failures — which is why preformed metal crowns seal, protect and outlast piecemeal repairs in severe molars. Ending with extraction timing around second-molar development signals a view across the whole developing dentition. ## Frequently asked questions ### What defines molar incisor hypomineralisation? Demarcated, qualitative enamel opacities of systemic origin affecting one to four first permanent molars, often with incisor opacities, diagnosed by EAPD criteria after excluding other causes. ### What is post-eruptive breakdown in MIH? Fracture and loss of the poorly mineralised enamel soon after eruption under ordinary mastication, creating defective surfaces that rapidly collect plaque and caries. ### How is MIH distinguished from enamel hypoplasia and fluorosis? Hypomineralisation affects enamel quality with demarcated opacities, hypoplasia affects enamel quantity with pits and grooves, and fluorosis gives diffuse, symmetric opacity patterns. ### Why do composite restorations often fail in hypomineralised molars? The defective enamel does not etch and bond reliably, so margins leak and shed unless preparation extends to sound enamel — or a full-coverage option is chosen. ### When is extraction of a hypomineralised first molar considered? In severe breakdown with sensitivity and repeated restoration failure, extraction timed orthodontically to the developing second molar can give better space closure than endless repair.