Dental caries burden across age groups in Kerman province, Iran (1992-2025): a systematic review and meta-analysis

Kerman is Iran's largest province, with a population exceeding three million and documented socioeconomic disparities in oral health outcomes. This systematic review and meta-analysis aimed to characterize temporal trends in dmft/DMFT indices across six age groups in Kerman province over nearly three decades.

This study was conducted in accordance with the PRISMA 2020 guidelines. English and Persian databases, including PubMed, Scopus, Embase, Web of Science, and SID, were searched up to April 2026. This search was supplemented by a manual review of dental master's theses from Kerman Dental School and national oral health reports. Cross-sectional studies reporting dmft/DMFT indices in the general healthy population of Kerman province were included. Two reviewers independently performed study selection, data extraction, and quality assessment using the Newcastle-Ottawa Scale. Pooled estimates and 95% confidence intervals (CI) were calculated using a random-effects model. Heterogeneity was assessed using I² and Q statistics. Subgroup analyses by time period (prior to 2015 versus 2015 to present) and univariable meta-regression with four pre-specified covariates were performed to explore sources of heterogeneity. The certainty of evidence was assessed using the GRADE framework.

A total of 49 studies (comprising 26 peer-reviewed articles, 19 theses, and 4 national reports) were included. The pooled dmft was 3.55 (95% CI: 3.26-3.84) for children aged 3-6 years, 5.12 (95% CI: 4.74-5.50) for 6-year-olds, and 4.09 (95% CI: 2.73-5.46) for 9-year-olds. Pooled DMFT values were 2.04 (95% CI: 1.70-2.39) for 12-year-olds and 2.61 (95% CI: 1.38-3.84) for the 12-15-year age group. In adults aged 35-44 years, the pooled DMFT was 13.80 (95% CI: 10.80-16.78). Meta-regression and subgroup analysis revealed a significant increasing temporal trend in the 3-6-year group (+ 0.21 units per year; p < 0.001), while geographic location significantly predicted caries levels in 6-year-olds (p < 0.001). Heterogeneity was very high across all age groups (I² > 94%, p < 0.001). The certainty of evidence was rated as very low for all age groups using the GRADE framework.

The dental caries burden in Kerman province remains high across all age groups, with a significant worsening trend in early childhood caries. Due to the very low certainty of current evidence, a standardized provincial oral health survey is needed. Future strategies should prioritize expanded water fluoridation and targeted community-based preschool interventions.