The accuracy of intraoral scanners (IOS) for edentulous arches varies by region and scanner type, but research demonstrates clinically acceptable results in most denture-bearing areas. A systematic review of 12 studies found that IOS accuracy for clear anatomic landmarks, such as hard tissues with attached mucosa, was comparable to that of conventional edentulous arch impressions. (1) However, specific regions show varying accuracy levels:

Accuracy by anatomical region:

– Alveolar ridge and vestibular ridge: Highest accuracy, within the clinically acceptable threshold of 300-500 ?m (matching tissue compressibility) (2)

– Peripheral borders and palatal seal areas: Maximum deviations observed, requiring careful interpretation (1)

– Soft palate and mobile tissues: Higher discrepancies recorded, as IOS captures tissues in mucostatic rather than functional conditions (1)

Clinical implications: Research by Chebib et al. found that while a 0.45mm discrepancy across the entire scan surface may seem minimal, it can result in a 2-3 times reduction in denture base retention. (1) This underscores the importance of proper scanning technique and post-scan verification, particularly in peripheral seal areas critical for denture retention.

The accepted accuracy threshold for complete dentures is 300-500 ?m, which corresponds to mucosal tissue compressibility. Deviations within this range can be absorbed by underlying tissues, while larger discrepancies may create friction areas and sore spots, and may require additional adjustment appointments. (2)

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1. Srivastava G, et al. Accuracy of Intraoral Scanner for Recording Completely Edentulous Arches—A Systematic Review. Dent J (Basel). 2023;11(10):241. https://www.mdpi.com/2304-6767/11/10/241

2. Clinical Oral Investigations. Accuracy of intraoral scans of the edentulous maxilla—an in vitro study. 2025. https://link.springer.com/article/10.1007/s00784-025-06419-w

Scanning completely edentulous arches presents unique challenges not encountered with dentate cases:

Challenge 1: Capturing mobile and poorly traceable structures
Mobile tissues, such as the soft palate and peripheral borders, show the greatest scan discrepancies. The sublingual areas and vestibule in the mandibular arch exhibit the greatest variation. (1)

Solution: While IOS records tissues in a mucostatic condition, operators can improve accuracy by:

– Using gentle, consistent tissue retraction during peripheral border scanning
– Taking multiple scans of problematic areas and selecting the best capture
– Understanding that some manual refinement of peripheral borders may be necessary in the CAD design phase

Challenge 2: Scanner tip access limitations
The IOS tip size can hinder access around the tuberosity in the posterior maxilla, limiting the ability to record the functional depth of the vestibule. (1)

Solution:
– Select scanners with appropriate tip sizes for edentulous workflows (larger tips show better trueness and precision) (3)
– Use systematic scanning patterns that approach difficult areas from multiple angles
– Consider supplementary scans with repositioning to capture complete anatomical detail

Challenge 3: Lack of anatomical reference points
Unlike dentate cases, where teeth provide fixed reference points, edentulous arches offer fewer landmarks for scanner orientation.

Solution:
– When possible, use the patient’s existing dentures (even if broken or poorly fitting) to establish reference relationships
– Perform reline impressions with dentures in situ, then scan the dentures separately and correlate digitally
– Include comprehensive photographic documentation, especially of dentures in occlusion, to assist lab technicians

Challenge 4: Distinguishing between adequate and inadequate scans. Operators may not immediately recognize when peripheral areas are inadequately captured.

Solution:
– Develop a systematic quality-check protocol reviewing all critical anatomical areas before patient dismissal
– Pay particular attention to color-coded deviation maps if your scanner software provides real-time feedback
– Establish communication protocols with your dental lab to verify scan completeness

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1. Srivastava G, et al. Accuracy of Intraoral Scanner for Recording Completely Edentulous Arches—A Systematic Review. Dent J (Basel). 2023;11(10):241. https://www.mdpi.com/2304-6767/11/10/241

3. Hayama H, et al. Comprehensive Review of Factors That Influence the Accuracy of Intraoral Scanners. Diagnostics. 2023;13(21):3291. https://www.mdpi.com/2075-4418/13/21/3291