National and Subnational Trend of Dental Caries of Permanent Teeth in Iran, 1990-2017

There are currently no integrated data on the trend of dental caries amongst distinct age groups in Iran. We aimed to assess the national and subnational trend of dental caries of permanent teeth in Iran from 1990 to 2017.

A literature search about dental caries and the decayed-missing-filled teeth index (DMFT) was performed in PubMed, Web of Science, Scopus, and 3 national databases (in Persian). All eligible national oral health surveys in these 28 years were included. We categorised and aggregated the DMFT values and their components based on age (5-year-based groups from 5 to 9 to 60+ years), sex, year, and province. The data for missing spots were estimated using the spatiotemporal Bayesian hierarchical model. We used the bootstrap method in multilevel models to predict the uncertainty interval (UI) of the modelled results.

Nationally, the all-ages mean DMFT increased by nearly 58.0% (6.8 [95% UI, 4.1-10.5] in 1990 to 10.8 [95% UI, 7.5-14.5] in 2017). Decayed teeth (DT) and missing teeth (MT) rose by 84.5% and 31.6% during this period, respectively. Filled teeth (FT) showed almost a 2.6-fold increase in the same period from 0.6 (95% UI, 0.01-1.6) in 1990 to 1.7 (95% UI, 0.6-2.8) in 2017. The proportion of DT and FT continuously increased in both sexes. In 2017, the highest DT, MT, and FT were estimated in the 25-29 (4.9 [95% UI, 2.5-7.2]), 60+ (21.5 [95% UI, 17.5-25.4]), and 35-39 (2.6 [95% UI, 1.3-4.0]) year age groups.

Caries of permanent dentition levies a growing burden on the Iranian population. Considering the continuous increase in caries during the 1990-2017 period, Iranian policymakers should pay heed to these findings and react more proactively to mitigate this perpetuating issue. Implementing nationwide interventions such as sugar consumption management should be encouraged to achieve sustainable outcomes in this regards.