STL subtraction: A new method for digital treatment planning

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STL subtraction: A new method for digital treatment planning

Posted on: December 12, 2019

When combined with traditional treatment planning methods, digital tools can offer a more conservative approach and more predictable
final results3, 6. The merging of 2D designs and 3D digital models allows prosthetic constructions to be completed digitally, and scanned models can now be transferred to the final design of the restoration17. Detailed functional analysis of dentition using provisionals to change or adapt the smile design is also needed4, 16. The success of an aesthetic treatment relies on good planning and screening of patients; this is the case whether it is a crown-lengthening procedure or implant treatment. Optimal aesthetic results require a suitable smile design which fulfils the patient’s expectations.

When planning a crown-lengthening procedure, the volume of soft and hard tissues which needs to be removed should be carefully calculated. 3D surgical guides can assist with this, allowing us to visualise and measure the alveolar bone; plan the positions of prosthetic designs; and produce wax-ups and mock- ups inside the patient’s mouth. Initially, implant therapy was surgically-led and implants were placed according to the amount of available bone which was detected using traditional radiography. This approach often led to incorrect positioning of prostheses because implants were placed in the wrong 3D position. The consensus today is that the starting point for treatment planning should be the final design of the prosthesis, and the use of digitally planned surgical guides is common.

This paper describes a fully digital protocol which allows clinicians to plan, visualise, and functionally test designs, enabling the design of digital surgical guides and provisional constructions for complex aesthetic cases before irreversible dental procedures are carried out.

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