Understanding Digital Impression Technology
Digital impression technology (also called digital scanning or optical scanning) captures 3D digital images of teeth and gingival tissue, replacing traditional impression materials (alginate, polyether, silicone) with digital data.
Intraoral scanners use structured light, laser triangulation, or confocal microscopy to capture high-resolution 3D images. Data is processed into 3D models viewable and manipulated on computer.
How Scanners Work
Most intraoral scanners use structured light technology: a projector displays patterns on tooth surfaces, and cameras capture the light reflection. Software calculates the 3D position of every point based on light distortion.
The scanner moves systematically around teeth, capturing images from multiple angles. Software stitches the images together creating a complete 3D model of the tooth preparation, adjacent teeth, and opposing arch.
Advantages Over Traditional Impressions
Patient comfort: No gagging from impression materials, no taste of impression material.
Accuracy: Digital data captures geometry with micrometer precision—often more accurate than traditional impressions.
Efficiency: Scanning takes 2-3 minutes compared to 10-15 minutes for traditional impressions.
No retakes: Images are instantly viewable—if inadequate, rescanning is immediate rather than awaiting laboratory feedback on inadequate traditional impression.
Immediate sharing: Digital files transmit instantly to laboratory, eliminating shipping delays.
Gag reflex elimination: Patients with severe gagging benefit from non-invasive scanning.
Esthetic documentation: Intraoral images document tooth color and surrounding tissues for restoration design.
Accessibility: Digital files are stored indefinitely and retrieved easily for future use.
Scanner Types and Systems
Structured light scanners:
- 3Shape TRIOS
- Carestream CS3600
- Planmeca Emerald
Laser triangulation scanners:
- iTero (Align Technology)
- Medit i700
Handheld versus desktop: Some scanners are handheld wands, others mount on robotic arms.
Color capture: Some scanners capture color data; others require separate photographic documentation of tooth shade.
Clinical Applications
Crown preparation: Most common application—scanning replaces traditional impressions for crown restorations.
Multiple tooth restorations: Scanning of preparation coordinates with opposing and adjacent teeth.
Implant impressions: Digital scanning captures implant position and abutment geometry.
Orthodontics: Scanning captures tooth position for treatment planning.
Dentures: Scanning captures residual ridge for denture design.
Inlays, onlays, veneers: Any restoration requiring precise impression benefits from digital scanning.
Aligners: Scanning captures teeth for custom aligner fabrication.
Accuracy
Modern scanners achieve accuracy of 10-20 micrometers—submicron precision exceeding traditional impression accuracy.
Digital data captures small details like preparation margins and line angles with precision.
The combination of scanner precision and digital transmission eliminates additional errors from traditional impression transport and model pouring.
Limitations
Initial cost: Intraoral scanners cost $15,000-$40,000, requiring practice investment.
Learning curve: Dentists and staff require training in proper scanning technique.
Laboratory transition: Laboratories require compatible software to accept digital impressions.
Special patient situations: Some patients with limited mouth opening or extreme gagging may have difficulty cooperating with scanner.
Shade capture: Separate photographic documentation of tooth color is sometimes necessary (though some scanners incorporate color).
Dry field requirement: Adequate visibility requires reasonably dry field—severe saliva flow may require isolation.
Workflow Integration
Traditional workflow:
- Tooth preparation
- Impression taking
- Temporary crown placement
- Impression shipping to laboratory
- Laboratory fabrication (3-5 days)
- Patient return for temporary removal and final restoration delivery
Digital workflow:
- Tooth preparation
- Digital scanning
- Temporary crown placement (or skip with CAD/CAM single-visit)
- Digital file upload to laboratory
- Laboratory fabrication (2-3 days)
- Patient return for temporary removal and final restoration delivery
Alternatively with CAD/CAM:
- Tooth preparation
- Digital scanning
- Design and milling (1-2 hours)
- Immediate restoration delivery (single visit)
Laboratory Requirements
Not all laboratories accept digital impressions initially—many operated purely with traditional models.
Modern laboratories increasingly have digital design software allowing 3D model manipulation and fabrication from digital data.
Some laboratories convert digital data to physical models for traditional handcrafted restoration fabrication.
Direct digital-to-fabrication is increasingly common, particularly for CAD/CAM processes.
Cost-Benefit Analysis
Scanner cost: $15,000-$40,000 equipment cost.
No impression material cost: Eliminates material costs (minor savings).
Reduced mistakes: Fewer rescans and retakes saves time and reduces remake costs.
Faster delivery: Quicker turnaround due to instant transmission.
Patient satisfaction: Better patient experience with non-invasive scanning.
Market differentiation: Digital technology market advantage attracting technology-interested patients.
Break-even: Practices typically break even in 2-3 years.
Artificial Intelligence Integration
AI applications emerging:
Automatic margin detection: Software identifies preparation margins automatically.
Design suggestions: AI suggests optimal restoration geometry based on anatomic parameters.
Quality assurance: AI checks scan quality and flags incomplete areas requiring rescanning.
Predictive analytics: Software predicts restoration fit and suggests design modifications.
Hybrid Approach
Many practices use hybrid approach: digital scanning for routine cases and traditional impressions for complex cases requiring exceptional precision.
Specific materials: Some patient preferences for traditional impression texture or taste (unusual, but some patients request it).
Future Developments
Improved color capture: Better integration of color data into digital workflow.
Full-mouth scanning: Efficiency improvements may enable entire mouth scanning in seconds.
Augmented reality: AR visualization of planned restorations from scanned anatomy.
Wireless transmission: Improved connectivity eliminates cables and improves portability.
Lower costs: As technology matures, equipment costs decrease.
Conclusion
Digital impression technology represents the modern standard for dental impression capture. Superior accuracy, patient comfort, and workflow efficiency have made traditional putty impressions obsolete in forward-thinking practices. For patients requiring restorations, digital scanning provides superior experience and outcomes compared to traditional impression materials.
Ask your dentist whether they use digital impression technology—if so, you'll enjoy the comfort and precision advantages of this modern approach.