Overview: Understanding and resolving washed or tissue-obscured margins is essential for creating accurate digital impressions for dental restorations.
Identify Washed Margins in Scans
Washed margins occur when tissue, blood, saliva, or other substances obscure the tooth margin in a digital scan. This obstruction prevents the scanner from capturing the precise edge of the preparation, making it difficult for designers to identify the margin accurately.
Implement Prevention Strategies
The following prevention strategies significantly improve the margin quality of digital scans.
Use Retraction Techniques
Utilize one or two retraction cords along with hemostatic agents to create a clear physical separation between the tooth margin and the surrounding gingival tissue.
Note: Refer to the Recommended Crown and Bridge Retraction Techniques article for detailed instructions on retraction.
Utilize Assistant Support
A dental assistant can help manage saliva flow and use air-water tips to keep the preparation site dry. An assistant can also provide better visibility by retracting cheeks or the tongue during the scanning process.
Follow Tips for Improved Scan Quality
Precision in scanning technique is necessary to avoid margin errors.
Optimize Mirror Positioning
Position the scanner mirror tip close to the margin when scanning subgingival areas. Directing the scanner tip closer to the preparation allows the light to reach the margin without being blocked by surrounding structures.
Adjust Mandibular Position
Guide the patient to shift their jaw toward the side being scanned. Adjusting the mandibular position provides more space for the scanner head in posterior areas, ensuring the scanner captures a complete view of the margin.
Enable High Definition Features
Use the HD Scans feature within the Chairside software. The HD Scans tool provides detailed analysis and higher-resolution imaging for critical margin areas.
Apply CAD/CAM Spray
Apply CAD/CAM spray when scanning gold crowns or highly reflective surfaces. The spray reduces reflection, which helps the scanner detect the margin more accurately.
Review Scan Examples
Reviewing the difference between high-quality and low-quality scans helps in detecting errors before submitting a case.
High-Quality Scans
In a high-quality scan, there is a clear distinction between the tooth structure and the margin. The prepared surface appears as one smooth, continuous area without overlapping soft tissue.
Poor-Quality Scans
In a poor-quality scan, tissue covers the margin and masks the distinction between the tooth and soft tissue. Washed margins require digital adjustment and designer margin estimation, which may reduce restoration accuracy.
Access Live Scan Review Assistance
The Live Scan Review team is available to offer real-time guidance for optimal scanning results. Refer to the Contact Us article to learn how to connect with a specialist for assistance during a live scan.