# Distribution and Clinical Characteristics of MIH in Schoolchildren From the Central Peruvian Jungle: A Cross‑Sectional Study

## TL;DR

This study found that 18.8% of schoolchildren in Peru's Central Jungle region have a tooth enamel defect called MIH, mainly affecting molars and showing specific patterns and severity.

## Contribution

The study provides new data on MIH prevalence and clinical characteristics in a previously understudied jungle region of Peru.

## Key findings

- MIH prevalence was 18.8% in 6–12-year-old children from the Central Jungle region of Peru.
- First permanent molars were more affected than incisors, with molars showing greater severity and higher rates of post-eruptive breakdown.
- Pattern I was most common (78.7%), while patterns II/III showed male predominance and more severe lesions.

## Abstract

Molar incisor hypomineralisation (MIH) is a developmental enamel defect that predominantly affects first permanent molars and frequently involves incisors. However, evidence on MIH prevalence and clinical presentation in jungle regions is limited.

To determine the distribution and clinical patterns of MIH among schoolchildren in the Central Jungle region of Peru.

This cross‐sectional study included 1500 schoolchildren aged 6–12 years from two public schools in Peru’s Central Jungle region, recruited through stratified random sampling. Two calibrated examiners diagnosed MIH using European Academy of Paediatric Dentistry (EAPD) criteria (inter‐examiner κ = [0.87]; intra‐examiner κ = [0.89]). Categorical variables were analysed using Pearson’s chi‐squared and Fisher’s exact tests (α = 0.05, 95% CI).

MIH prevalence was 18.8% (95% CI: [17.0–20.0]). First permanent molars were predominantly affected (upper: 84.8%, 285/336; lower: 90.9%, 288/317) compared to incisors. Pattern I distribution occurred in 78.7% of cases, while patterns II/III (21.3%) showed significant male predominance (p = 0.008). Molars exhibited significantly greater severity (p = 0.001) with white–cream opacities (28.5%) and predominantly Type III lesions, presenting higher post‐eruptive breakdown and atypical caries rates. Incisors displayed mainly mild Type I demarcated opacities. Upper lateral incisors demonstrated left‐sided predominance (p = 0.016).

MIH prevalence was 18.8% among schoolchildren in Peru’s Central Jungle region. First permanent molars were predominantly affected (upper: 84.8%; lower: 90.9%) compared to incisors. Pattern I distribution occurred in 78.7% of cases, while patterns II/III (21.3%) showed significant male predominance. Molars exhibited greater clinical severity with white–cream opacities, Type III lesions, and higher rates of post‐eruptive breakdown and atypical caries, whereas incisors presented mainly mild demarcated opacities.