Background and Objectives: Since the 1980s a caries decline has been observed in Germany, particularly among 12-year-olds, with 81 % being caries-free in 2014. Concurrently, MIH has become more prevalent. These developmental defect of enamel results from an immature amelogenesis, and the precise cause and socio-economic correlations remain unclear. While MIH prevalence data exist from two birth cohort studies (GINI and LISA) in Bavaria, this study aimed to complement them, examining regional variations through a population-representative cross-sectional study. The objective was to comprehensively assess the oral health status of third and fourth-grade schoolchildren in Northern Bavaria, specifically considering MIH. Materials and Methods: In this epidemiological study on the oral health of Bavarian schoolchildren in the school year 2022/23, dental examinations were conducted from March 2023 to Juli 2023 at a total of 87 randomly selected schools, 46 in Northern Bavaria and 41 in Southern Bavaria. Coordinated by the LAGZ in collaboration with LMU Munich and JLU Giessen, the study followed established national procedures. The goal was to examine 5000 students (2500 each in Northern Bavaria and Southern Bavaria) with an estimated accuracy of less than 2 % in the 95% confidence interval. School selection occurred after study approval using random sampling, considering population size and urban-rural distribution. Healthy third and fourth-grade schoolchildren with the erupted first permanent molars and written parental consent were included. Written information was provided to parents through detailed brochures sent to schools and online parent meetings. Dental examinations recorded clinical variables such as dental status, caries precursors, hypomineralisation (MMH/MIH), hypersensitivities, and fissure sealings. Data documentation was initially paper based, later digitized, and statistically analyzed. Statistical analyses comprised descriptive statistics, the Pearson’s Chi-square test, Pearson’s correlation analysis, and the Student's t-test, with the significance level established at α = 0.05. Results: In this study, a total of 2574 children in Northern Bavaria, with an average age of 9.8 years, were included. The prevalence of caries experience was 53.8 % (N = 1385), with 24.8 % (N = 637) of children having untreated carious lesions. The dmft value was 1.4 ± 2.1, and the DMFT value was 0.3 ± 0.8. The average caries experience per child was 1.6 teeth, with a restoration rate of 65.7 %. Children with caries experience in permanent teeth had an average of 2.0 ± 1.2 affected teeth. Gender differences suggested that boys were 23.0 % more likely to experience caries than girls (OR: 1.23; 95% CI [1.1, 1.4]). Geographically, children in urban schools were 25.2 % more susceptible to caries than children in rural schools (OR: 1.25; 95% CI [1.04, 1.51]). The prevalence of fissure sealings was 50.1 % (N = 322), with 47.2 % (N = 1215) of children having at least one intact sealing. A statistically significant association between fissure sealings and lower caries experience was observed (OR: 0,156; 95 % CI [0.09, 0.25]). Regarding MIH, a diagnosis was made in 17.1 % (N = 440) of children The average number of hypomineralised permanent teeth was 0.6 ± 1.5, and 14.5 % (N = 374) of children had demarcated opacities due to MIH. Severe forms of MIH were diagnosed in 11.1 % (N = 286) of children, with first permanent molars being most affected. The study revealed no statistically significant differences in geography (Pearson’s Chi-Square test, p = 0.722) or gender (Pearson’s Chi-Square test, p = 0.638). The prevalence of hypomineralised second primary molars (HSPM) was 7.0 %, and a statistically significant association between HSPM and MIH was found (Pearson’s Chi-Square test, p < 0.001). Children with HSPM had an odds ratio of 12.0 (95% CI [8.68, 16.72]) for MIH. Conclusions: The frequency of MIH in permanent teeth was higher than caries experience, necessitating targeted care strategies. The observed MIH prevalence of 17.1% exceeds the global average, indicating a higher need for treatment and raising questions about regional dental care. The positive trend of declining caries in permanent dentition continues, with preventive measures like fissure sealings being crucial. The persistently high caries experience in primary teeth calls for targeted prevention measures after school commencement. These findings highlight the complex dynamics of oral health in this age group and underscore the need for further research to optimize preventive and curative care.
