The global prevalence of apical periodontitis: a systematic review and meta-analysis

Apical periodontitis (AP) frequently presents as a chronic asymptomatic disease. To arrive at a true diagnosis, in addition to the clinical examination, it is mandatory to undertake radiographic examinations such as periapical or panoramic radiographs, or cone-beam computed tomography (CBCT). Thus, the worldwide burden of AP is probably underestimated or unknown. Previous systematic reviews attempted to estimate the prevalence of AP, but none have investigated which factors may influence its prevalence worldwide.

To assess: (i) the prevalence of AP in the population worldwide, as well as the frequency of AP in all teeth, nontreated teeth and root filled teeth; (ii) which factors can modify the prevalence of AP.

A search was conducted in the PubMed-MEDLINE, EMBASE, Cochrane-CENTRAL, LILACS, Google scholar and OpenGrey databases, followed by hand searches, until September 2019. Cross-sectional, case-control and cohort studies reporting the prevalence of AP in humans, using panoramic or periapical radiograph or CBCT as image methods were included. No language restriction was applied. An adaptation of the Newcastle-Ottawa Scale was used to evaluate the quality of the studies. A meta-analysis was performed to determine the pooled prevalence of AP at the individual level. Secondary outcomes were the frequency of AP in all teeth, nontreated teeth and rootfilled teeth. Subgroup analyses using random-effect models were carried out to analyse the influence of explanatory covariables on the outcome.

The search strategy identified 6670 articles, and 114 studies were included in the meta-analysis, providing data from 34 668 individuals and 639 357 teeth. The prevalence of AP was 52% at the individual level (95% CI 42%-56%, I²  = 97.8%) and 5% at the tooth level (95% CI 4%-6%; I²  = 99.5%). The frequency of AP in root-filled teeth and nontreated teeth was 39% (95% CI 36%-43%; I²  = 98.5%) and 3% (95% CI 2%-3%; I²  = 99.3%), respectively. The prevalence of AP was greater in samples from dental care services (DCS; 57%; 95% CI 52%-62%; I²  = 97.8%) and hospitals (51%; 95% CI 40%-63%; I²  = 95.9%) than in those from the general population (GP; 40%; 95% CI 33%-46%; I²  = 96.5%); it was also greater in people with a systemic condition (63%; 95% CI 56%-69%, I²  = 89.7%) compared to healthy individuals (48%; 95% CI 43%-53%; I²  = 98.3%).

The subgroup analyses identified explanatory factors related to the variability in the prevalence of AP. However, the high clinical heterogeneity and high risk of bias across the primary studies indicate that the findings must be interpreted with caution.

Half of the adult population worldwide have at least one tooth with apical periodontitis. The prevalence of AP is greater in samples from the dental care services, but it is also high amongst community representative samples from the general population. The present findings should bring the attention of health policymakers, medical and dental communities to the hidden burden of endodontic disease in the population worldwide.