Radiographic artifacts in the diagnosis of dental caries: systematic review with meta-analysis

The radiographic diagnosis of dental caries is often complicated by the presence of radiographic optical effects, such as the Mach band effect and triangular-shaped radiolucencies (TSR). These phenomena can give rise to false-positive diagnoses, especially in bite-wing radiographs, thus influencing clinical decision-making and possibly leading to overdiagnosis and overtreatment. The aim of this systematic review and meta-analysis was to clarify the real prevalence of these radiographic optical effects in dental radiographs and to quantify their influence on diagnostic errors in caries detection.

This systematic literature review follow the PRISMA guidelines and registered in PROSPERO (CRD420251083823), prior to its execution. Electronic searches were conducted on PubMed, Scopus and the Cochrane Library, with the addition of Grey literature and references of the main reviews on the topic. Inclusion criteria included clinical, in vitro and ex vivo studies evaluating the impact of TSR and Mach band effects on intraoral radiographs (bitewing or periapical), reporting diagnostic performance, prevalence or misinterpretation rates. Data extraction and risk of bias assessment (AXIS, QUADAS-2) were performed independently by two reviewers. Meta-analyses were performed using random effects models.

Of 640 identified reports, only five studies were included. The overall prevalence of non-carious TSR on maxillary molars was 26.44%, 270/1021. The meta-analysis showed that effects (TSR or Mach band) led to false positive diagnoses of caries or fractures, in approximately 13% of observations (60/464). Heterogeneity was high (I² > 90%) and the certainty of the evidence was classified as low to very low due to the type of studies included and the consistency indices.

Radiographic optical effects, especially TSR and Mach band effect, are highly prevalent in bitewing images and significantly increase the risk of false positive caries diagnoses, especially in children. Given the low certainty of the available evidence, clinicians should interpret radiographic findings with caution and always correlate them with a thorough clinical examination. Further high-quality research is needed to develop standardized diagnostic criteria and strategies to mitigate radiographic optical effects in dental practice.