Case Study

Understanding the Impact of Inaccurate Scans on Dental Restorations

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Introduction


In the world of digital dentistry, the accuracy of scans plays a crucial role in the successful fabrication of dental restorations. However, many practitioners may not be aware of the potential pitfalls associated with inaccurate scans and the implications they can have on the final outcome of their restorations. 

Artefact created by the scanning software

The Issue with Automatic Hole Filling


When scans are taken without ensuring that all holes are filled, scan software automatically attempts to fill these gaps. While this feature may seem convenient, it is not always accurate. In fact, automatic filling can sometimes create artefacts that need to be manually corrected by the dental technician. This procedure will not guarantee a correct outcome for the dental restoration required and complicates the work for us as dental technicians. We also find that in these situations, remakes occur more often due to poor fitting.


Holes automatically filled by the scan software – creates a rough surface
Holes in scan image received from the IOS

Impact on Restoration Fit


Even with meticulous correction efforts by a dental technician, the resulting restoration may not perfectly reflect the natural shape of the tooth. This becomes particularly problematic when the inaccuracies occur in critical areas such as the margin line or contact area walls. Such inaccuracies can lead to incorrect fitting of the crown, resulting in issues like margin line discrepancies or improper contact points. 


Rubber Dam captured in the scanning process


Workflow Suggestions for Dentists


To mitigate these issues, it is essential for dentists to take proactive measures during the scanning process. Here are some workflow suggestions: 

1. Double Check Critical Areas: Dentists should not rely solely on the scan software’s automatic features. Instead, they should manually inspect critical areas such as the margin line, contact points, and interproximal spaces to ensure they are accurately captured in the scan. This involves zooming in on these areas and verifying that all details are clearly visible before finalising the scan. 

Example: Before finalising the scan, dentists should use the intraoral scanner’s zoom function to closely examine the margin line of the prepared tooth. They should ensure that the scan captures the entire margin without any gaps or inaccuracies. Additionally, dentists can use a dental mirror to visually inspect hard-to-reach areas and confirm that they are adequately scanned. 

    2. Ensure Comprehensive Scans: Dentists should adopt a systematic approach to scanning that ensures all surfaces of the tooth preparation are thoroughly captured. This includes scanning the buccal, lingual, and occlusal surfaces from multiple angles to obtain a complete digital impression. Dentists should pay particular attention to areas with intricate anatomy, such as the gingival margin and proximal contacts, to ensure accurate representation in the scan.  

    Example: When scanning a prepared tooth for a crown restoration, dentists should begin by scanning the occlusal surface in a sweeping motion from mesial to distal. They should then capture the buccal and lingual surfaces by angling the scanner appropriately to access hard-to-reach areas. Finally, dentists should focus on scanning the gingival margin by gently retracting the soft tissues to expose the preparation margin for clear visualisation. 


    An ideal scan situation for the laboratory to work with

    3. Communication with Technicians: Effective communication between dentists and dental technicians is paramount to achieving optimal restoration outcomes. Dentists should provide detailed instructions and preferences to their dental technician regarding the design, material selection, and aesthetic considerations of the restoration. Additionally, dentists should be receptive to feedback from technicians and collaborate closely throughout the fabrication process to ensure the final restoration meets both clinical and patient expectations. 

    Example: Before sending the digital impression to the dental laboratory, dentists should include specific notes or annotations highlighting any unique characteristics or challenges associated with the case. For instance, if the patient has a history of bruxism or requires a restoration with precise occlusal adjustments, dentists should communicate these details to the technician to guide the fabrication process. Furthermore, dentists should be available for follow-up discussions with their dental technician to address any questions or concerns that may arise during restoration fabrication. 


    Conclusion


    Inaccurate scans can have significant implications for the fit and functionality of dental restorations. By understanding the potential challenges associated with automatic hole filling and taking proactive steps to ensure comprehensive scans, dentists can help support dental technicians in fabricating high-quality restorations that meet the needs of their patients. By implementing these comprehensive workflow suggestions, dentists can enhance the accuracy and quality of their digital impressions, ultimately leading to improved restoration fit, function, and patient satisfaction. 

    Providing evidence-based support for the issues outlined in this blog post regarding inaccurate scans and their impact on dental restorations via reference studies and expert opinions within the field of digital dentistry is a great place to expand on this area in digital dentistry. By understanding these issues better, we can then offer practical suggestions for dentists to improve their scanning workflow and support technicians in fabricating high-quality dental restorations. 


    Pietro Bonanno

    Digital Lead Dental Technician