This study presents a systematic review with meta-analysis to evaluate the success rates of endodontic retreatments in teeth where separated instruments are located within the roots. The search and selection of studies were conducted across two databases, SCOPUS and PubMed, as well as the Cochrane Library registry, yielding a total of 1620 records. Following the selection process, 11 studies were included in the systematic review. Overall, out of 1133 retreated teeth, there were 172 failures in instrument removal and 55 perforations. The meta-analysis results indicate that failures are more frequent when instruments are located in the apical third, with a failure rate of 21%, compared to an 8.8% failure rate in the middle/coronal third. The anatomy of the root canals, particularly the location of the separated instruments, significantly influences the success rates.

Objectives: 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. Methods: 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. Results: 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. Conclusions: 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.

Purpose of Review: The accurate execution of endodontic access is crucial for the success of therapy, influencing various phases of canal treatment. Traditional approaches prioritize a convenient form and broad endodontic opening to facilitate subsequent procedures. Minimally invasive dentistry, which prioritizes dentin preservation, is increasingly being embraced. Nonetheless, the scientific evidence supporting this approach remains limited, and concerns have been raised regarding its influence on the various phases of root canal treatment. Recent findings: Clinical studies explore the risk of dental fractures during endodontic treatment, considering the removal of dental tissue. Traditional openings may increase fracture risk due to reduced resistance to masticatory loads. This review aims to compare the fracture resistance of teeth prepared with minimally invasive access preparation to those treated with traditional endodontic access cavities. The review protocol was developed in accordance with the Cochrane Handbook guidelines and was registered in INPLASY, while the manuscript was drafted following the PRISMA statement; after the study identification and selection process, included a total of 5 studies. We pooled fracture-load data using the standardised mean difference (SMD) because studies used different scales. SMD > 0 favours minimally invasive access cavities (NAC) (i.e., teeth with NAC sustained a greater load than teeth with traditional endodontic access (TEC); the magnitude expresses the difference in standard deviations). Given the expected variability between studies, a random-effects model was applied alongside the fixed-effects model: 0.97 [0.65, 1.29]; Chi2 36.88, df = 9 ( P < 0.0001), I ² = 76%. Summary: The data derived from the meta-analyses may offer valuable insights for clinicians performing endodontic treatments using specific access cavity designs. The minimally invasive approach to endodontics with an ultraconservative or minimally invasive access preparation may be a viable solution in cases where the fracture resistance of a tooth is crucial. Future studies should focus primarily on aspects related to the increased difficulty in localizing orifices and the presence of debris that could affect the advantages obtained on fracture resistance with NAC. Ultraconservative techniques are characterized by cavity designs that show superior fracture resistance, suggesting enhanced resilience to masticatory loads when compared to traditional endodontic access cavities.