Clinical & Digital Workflow Guidance
How Scanning Strategies Influence Intraoral Scanner Accuracy
Intraoral scanner accuracy depends not only on the device itself, but also on how the scan is performed. A 2023 systematic review and meta-analysis published in the Journal of Advanced Prosthodontics provides one of the most comprehensive evaluations to date, reviewing 55 studies and performing pooled analysis on 15 high-quality in-vitro trials. This page summarizes the findings most relevant to restorative dentists and digital workflows.
Key Findings from the 2023 Meta-Analysis
According to the analysis (Hardan et al., 2023) and the PMC full-text version:
- Dry conditions significantly improve intraoral scanner accuracy (P < .001).
- S-shaped scanning patterns produce higher trueness and precision than linear passes.
- The use of artificial landmarks improves both precision and trueness (P < .02).
- Ambient light (room vs zero light) does not significantly affect accuracy (P ≥ .16).
- Scanning-aid liquids and sprays impacted precision more than trueness.
Many of these findings are visually depicted in the forest plots on pages 4–9 of the linked article, particularly:
- Page 4: Humidity increases error; dry scans outperform wet scans
- Page 8: Artificial landmarks improve precision/trueness
- Page 9: S-shaped scanning patterns produce more accurate results than linear patterns
Primary Evidence Source
Hardan L, Bourgi R, Lukomska-Szymanska M, et al. Effect of scanning strategies on the accuracy of digital intraoral scanners: a meta-analysis of in vitro studies. J Adv Prosthodont. 2023;15:315-332.
How Scanning Patterns Affect IOS Accuracy
The meta-analysis showed a consistent advantage for S-shaped scanning patterns, reducing deviation compared with linear scan paths. This effect is clearly illustrated in the forest plots on page 9 of the article, where S-shaped scans outperform linear scans in both trueness and precision.
Clinical takeaway: Avoid long straight passes; incorporate subtle S-curves to maintain geometry continuity and reduce stitching error.
The Impact of Humidity & Saliva
Consistent with other literature, this meta-analysis confirmed that humidity is one of the strongest negative influences on scan accuracy. Page 4 of the article shows a forest plot comparing wet vs dry conditions, demonstrating significantly higher deviation under humid or saliva-contaminated surfaces.
Clinical takeaway: Moisture management remains essential even with advanced scanners.
Use of Artificial Landmarks
In edentulous areas or regions with limited surface detail, artificial landmarks significantly improve scan quality. Page 8 of the article compares scans with vs without landmarks and shows noticeable improvements in both precision and trueness.
Clinical takeaway: Consider palatal or resin markers in low-texture areas or edentulous spans.
Does Operatory Lighting Matter?
Surprisingly, the meta-analysis found no significant difference between room light and zero-light conditions (P = 0.27 and P = 0.16). This is shown in the illumination forest plots on page 8.
Clinical takeaway: Follow manufacturer guidance, but normal operatory lighting is generally sufficient.
Summary for Clinical Practice
- Scan in dry conditions whenever possible.
- Use S-shaped scanning paths rather than long linear passes.
- Employ artificial landmarks in low-texture or edentulous regions.
- Lighting is a minor factor; humidity control is far more important.
- Scanning-aid materials may help in certain cases but introduce variability.