Overview: This article covers the step-by-step scanning workflow for Chairside Tooth-Supported Overdentures Using Existing Dentures Case Setup using Dandy Chairside scanning software.
Clinical Scenarios
This scanning workflow applies to two distinct clinical scenarios:
The patient has an existing complete denture along with retained teeth or roots that the denture sits over.
The patient has an existing complete tooth-retained overdenture.
Required Scan Materials
The scan data required by the design laboratory depends entirely on the number of arches being fabricated for the patient.
Single Arch Scans
If you are fabricating a single arch overdenture, you must capture the following three scans:
An extraoral 360-degree scan of the existing reference denture.
An intraoral scan of the opposing arch.
Two intraoral bite scans captured from the molar to the midline.
Dual Arch Scans
If you are fabricating dual arch overdentures, you must capture the following three scans:
An extraoral 360-degree scan of the existing upper reference denture.
An extraoral 360-degree scan of the existing lower reference denture.
Two intraoral bite scans captured from the molar to the midline.
Lower Overdenture Extraoral Steps
When scanning a lower overdenture extraorally, perform the steps in this exact sequence: Intaglio surface, peripheral borders, cameo surface, and then the occlusal surface.
Intaglio Surface: Begin scanning on the intaglio surface of the lower overdenture.
Peripheral Borders: Use a "rocking and rolling" motion to move the scanner wand from the intaglio surface toward the peripheral border, then roll back toward the intaglio surface. Repeat this motion until the entire peripheral border is completely scanned.
Cameo Surface: Rock the scanner wand from the buccal border toward the buccal or facial tooth surface, then roll back toward the border. Repeat this process until all buccal and facial surfaces are scanned.
Occlusal Surface: Rock the scanner wand from the buccal tooth surface to the occlusal surface, then move to the lingual tooth surfaces before rolling back toward the occlusal surface. Repeat this process until all of the anatomical tooth surfaces are scanned.
Data Evaluation: Inspect the finished lower overdenture scan for missing data and rescan any incomplete areas immediately.
Upper Overdenture Extraoral Steps
When scanning an upper overdenture extraorally, perform the steps in this exact sequence: Intaglio surface, peripheral borders, cameo surface, and then the occlusal surface.
Intaglio Surface: Begin scanning on the intaglio surface of the upper overdenture. Slowly sweep the scanner wand from side to side, working incrementally to capture the majority of the palate surface.
Peripheral Borders: Use a "rocking and rolling" motion to rock the scanner wand from the intaglio surface over the peripheral border, then roll back toward the intaglio surface. Repeat this motion until the entire peripheral border is completely scanned.
Cameo Surface: Rock the scanner wand from the buccal border toward the buccal or facial tooth surface, then roll back toward the border. Repeat this process until all buccal and facial surfaces are scanned.
Occlusal Surface: Rock the scanner wand from the buccal tooth surface to the occlusal surface, then move to the lingual tooth surfaces before rolling back toward the occlusal surface. Repeat this process until all of the anatomical tooth surfaces are scanned.
Data Evaluation: Inspect the finished upper overdenture scan for missing data and rescan any incomplete areas immediately.
Techniques for 360-Degree Scanning
Implement the following technical guidelines to ensure accuracy during extraoral 360-degree scanning:
Hold the prosthesis securely in your non-dominant hand and hold the scanner wand in your dominant hand.
Manipulate the scanner wand and the overdenture simultaneously to capture difficult angles.
Focus your attention primarily on the computer screen during scanning, and look down at the physical overdenture intermittently as needed.
Pause the scanner wand frequently to evaluate the captured scan data for discrepancies, holes, or distortion.
When turning the scanner wand back on after a pause, start on a region that has already been successfully scanned. Allow the scanner software to recognize the existing data, then move the wand slowly toward the area with missing data.
Evaluate the final 360-degree scans in stone view to achieve a better visual breakdown of potential distortions.
Use the Twist Technique to accurately scan any deep undercuts located on the flanges.
Bite Scan Procedure Steps
Follow these sequential steps to perform the patient bite scan:
Place the overdenture or overdentures back into the mouth of the patient.
Stabilize the bite using blue bite registration material to prevent any physical movement or shifting during the scanning process.
Instruct the patient to remain completely still and not move or shift the bite.
Starting on the posterior teeth, slowly wave the scanner wand up and down to capture at least 2 to 3 millimeters of the patient's vestibule.
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Click the Next Bite button on the screen and repeat this exact procedure for the second bite scan. Note: If the bite scans do not automatically align, manually align the arch scans within the software interface, or click Reset to clear and repeat the bite scan.
Review and Ordering Procedures
Review the completed scans on the final page and verify the structural accuracy of the following components before submission:
Utilize the tools on the Review page.
Occlusion Accuracy: Confirm that the patient's occlusion paths are entirely correct.
Data Integrity: Confirm that there is no scanning distortion, alignment shifting, or missing scan data.
Review Tools: Utilize the tools located on the software Review page. Use the Stone tool to help evaluate the 3D data for hidden distortion or missing patches. Use the Annotate scans tool to edit screenshots of the scans and send the highlighted screenshots as notes directly to the lab designer.
Rescanning: If a specific scan appears distorted or inaccurate, click the button labeled A scan looks bad? Re-scan it.
Order Submission: If all scan data looks highly accurate, click the button labeled Start Ordering to finalize the case.