Accuracy between intraoral and extraoral scanning: Three-dimensional deviation and effect of distance between implants from two scanning methods

Analyzing the influence of scanning speeds and distances on digital intraoral scans: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the influence of scanning speed and distance on the precision and quality of digital intraoral scans.

DATA

The PICO strategy was employed to delineate the inclusion and exclusion criteria. The acquired records underwent filtration according to eligibility criteria, with essential information subsequently extracted. The meta-analysis, facilitated by Review Manager 5.4, utilized chi-square and the inconsistency index, along with forest plots. The standardized mean difference (SMD) was employed for the comparative analysis of study groups. Additionally, the study encompassed assessments of publication bias and the quality of included studies.

SOURCES

The search was conducted using three Internet databases: PubMed, ScienceDirect, and the Cochrane Library.

RESULTS

Among the evaluated scanners (Trios 3, Trios 4, iTero, Primescan, Medit i500), only TRIOS 3 exhibited a statistically significant sensitivity to scanning parameters (SMD = -4.03; 95% CI: -7.26 to -0.80; P = 0.01). Increased scanning distances and faster speeds markedly reduced its accuracy, likely due to its older optical technology lacking real-time error correction features present in newer models like TRIOS 4 and Primescan. No significant effects were observed for TRIOS 4, Primescan, or Medit i500 (P > 0.05), suggesting their advanced hardware/software mitigates parameter variability.

CONCLUSIONS

Clinicians using TRIOS 3 should prioritize shorter scanning distances (5-10 mm) and slower speeds to optimize accuracy, as its performance is highly dependent on operator-controlled parameters. In contrast, newer scanners (e.g., TRIOS 4, Primescan) demonstrate greater resilience to distance/speed variations, enabling flexible clinical workflows. These findings underscore the importance of device-specific protocols to enhance digital impression reliability in restorative and prosthetic dentistry.

Effect of scanning strategies on the accuracy of digital intraoral scanners: a meta-analysis of in vitro studies

PURPOSE

This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis.

MATERIALS AND METHODS

This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05.

RESULTS

The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16).

CONCLUSION

The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.