A Computer-Aided Removal Method of Undercuts in Crown Preparations

Abstract

The invention provides a computer-aided method for removing the undercut of a crown preparation, comprising the following steps: 1) calculating the undercut area: calculating the undercut area under the in-position direction according to the specified in-position direction; 2) undercutting Concave area conversion: use the return value of the undercut area as the index of the triangular face, and convert the triangular face into a mesh vertex; 3) Classify the vertices of the undercut area: classify the mesh vertices in the undercut area, and the mesh under the same classification The movement vectors of the grid vertices are the same when the undercut area is removed; 4) Undercut area removal: calculate the movement vectors required for the removal of the undercut area of ​​the grid vertices under each classification according to the projection method, and then move the grid vertices . The computer-aided method for removing the undercut of the crown preparation provided by the present invention can realize the automatic removal of the undercut area without human interference, and no new undercut area will appear, which is beneficial to the design of the later restoration; There are no restrictions on the orientation; it is suitable for various crown preparation models.

Description

technical field [0001] The invention relates to a method for removing an undercut of a crown preparation, in particular to a computer-aided method for removing the undercut of a crown preparation. Background technique [0002] In clinical practice, dental crown preparations are usually obtained by manual grinding in the patient's mouth by physicians. Due to the limited operating space and field of view of the oral cavity, it is inevitable that the prepared dental crown preparations will have undercut areas. The undercut area will make the restorative crown difficult to fit, so it is necessary to remove the undercut area on the crown preparation before designing the restoration. [0003] At present, the dental CAD systems in the world also have their own undercut removal methods, but the specific methods are not clear. At present, the undercut area can be removed by calculating the positioning direction to obtain the undercut area, and then manually remove the undercut area ...

AI Technical Summary

Problems solved by technology

However, there are the following problems for manually removing undercuts: 1) manual removal of undercut areas is easy to generate new undercut areas; 2) if the undercut area is small, it is difficult to accurately select; 3) for larger undercut areas There are different undercut depths in the area, and different removal displacements are required, which is difficult to implement manually

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