Automatic crown and gingiva detection from three-dimensional virtual model of teeth

A method for automatically identifying gingival tissue in a virtual three-dimensional model of anatomical structures of the teeth and associated gingival tissue in a dental arch, comprising the steps of:

• a) storing said model in a memory accessible to a general-purpose computer, said computer including a processing unit;
• b) providing machine readable instructions for execution by said processing unit, said instructions comprising instructions operating on said model in the following respects:
• 1) orientating said model with reference to a plane;
• 2) automatically determining local maxima of the model and areas bounded by said local maxima;
• 3) automatically determining saddle points between said local maxima in the model, said saddle points corresponding to boundaries between teeth;
• 4) determining the position of said saddle points along a dental archform, and
• 5) for each tooth, automatically identifying a path defining comprising a transition between teeth and gingival tissue and between adjacent teeth in said model and linking said saddle points, and identifying areas bounded by said path and in the direction away from said plane as corresponding to said gingival tissue.

In a system comprising a programmed computer containing instructions for separating virtual teeth from a virtual model of both teeth and gingival tissue, the improvement comprising:

• providing instructions for execution by said programmed computer that
• 1) automatically determine local maxima of the model and areas bounded by said local maxima;
• 2) automatically determine saddle points between said local maxima in the model, said saddle points corresponding to boundaries between teeth;
• 3) automatically determine the position of said saddle points along a dental archform, and
• 4) for each tooth, automatically identifying a path interconnecting said saddle points for said tooth, said line or lines comprising a transition between teeth and gingival tissue and between adjacent teeth in said model.