Inflating complete tooth into incomplete tooth

[nnistelrooij]

Hello!

I am working on intraoral scans for orthodontistry and would like to extract the individual teeth from the scan.
However, these intraoral scans are non-watertight and the scan does not include the approximal surfaces of neighbouring teeth.

I can get the tooth type (canine, molar, etc.) and the tooth shape without the approximal surfaces. My idea to convert this to make watertight teeth with approximal surfaces is as follows:

1. Get a watertight template of a complete tooth for each tooth type;
2. Make it slightly smaller than the incomplete tooth and place it inside as a deformable object;
3. Expand the template tooth;
4. expand it with deformation until it fully touches the rigid tooth from the inside;
5. Keep the deformed complete tooth as the final watertight tooth surface.

I have been trying to implement steps 2 to 4 and am really struggling.
This is my script so far:

def createScene(root):
    root.gravity = [0, -9.81, 0]
    root.dt = 0.01

    # plugins
    root.addObject('RequiredPlugin', name='MultiThreading') # Needed to use components [ParallelBVHNarrowPhase,ParallelBruteForceBroadPhase]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Collision.Detection.Algorithm') # Needed to use components [CollisionPipeline]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Collision.Detection.Intersection') # Needed to use components [LocalMinDistance]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Collision.Response.Contact') # Needed to use components [CollisionResponse]
    root.addObject('RequiredPlugin', name='Sofa.Component.AnimationLoop') # Needed to use components [FreeMotionAnimationLoop] 
    root.addObject('RequiredPlugin', name='Sofa.Component.Constraint.Lagrangian.Solver') # Needed to use components [LCPConstraintSolver] 
    root.addObject('RequiredPlugin', name='Sofa.Component.IO.Mesh') # Needed to use components [MeshOBJLoader]  
    root.addObject('RequiredPlugin', name='Sofa.Component.LinearSolver.Iterative') # Needed to use components [CGLinearSolver]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Mapping.Linear') # Needed to use components [BarycentricMapping]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Mass') # Needed to use components [UniformMass]  
    root.addObject('RequiredPlugin', name='Sofa.Component.MechanicalLoad') # Needed to use components [SurfacePressureForceField]  
    root.addObject('RequiredPlugin', name='Sofa.Component.ODESolver.Backward') # Needed to use components [EulerImplicitSolver]  
    root.addObject('RequiredPlugin', name='Sofa.Component.SolidMechanics.Spring') # Needed to use components [MeshSpringForceField]  
    root.addObject('RequiredPlugin', name='Sofa.Component.StateContainer') # Needed to use components [MechanicalObject]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Topology.Container.Constant') # Needed to use components [MeshTopology]  
    root.addObject('RequiredPlugin', name='Sofa.GL.Component.Rendering3D') # Needed to use components [OglModel]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Collision.Geometry') # Needed to use components [LineCollisionModel,PointCollisionModel,TriangleCollisionModel] 
    root.addObject('RequiredPlugin', name='Sofa.Component.Constraint.Projective') # Needed to use components [FixedProjectiveConstraint]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Engine.Select') # Needed to use components [BoxROI]  
    root.addObject('RequiredPlugin', name='Sofa.Component.Visual') # Needed to use components [VisualGrid] 
    root.addObject('RequiredPlugin', name='Sofa.Component.Constraint.Lagrangian.Correction') # Needed to use components [UncoupledConstraintCorrection]

    # animation loop
    root.addObject('FreeMotionAnimationLoop')
    root.addObject('LCPConstraintSolver', tolerance="1e-3", maxIt="1000")

    # collision handling
    root.addObject('CollisionPipeline', verbose=1, draw=1)
    root.addObject('ParallelBruteForceBroadPhase')
    root.addObject('ParallelBVHNarrowPhase')
    root.addObject('LocalMinDistance', name='Proximity', alarmDistance=0.15, contactDistance=0.05)
    root.addObject('CollisionResponse', name='Response', response="FrictionContactConstraint")


    root.addObject("VisualGrid", nbSubdiv=10, size=10)


    inside_tooth = root.addChild('Frog')

    inside_tooth.addObject('EulerImplicitSolver', rayleighStiffness="0.1", rayleighMass="0.1")
    inside_tooth.addObject('CGLinearSolver', iterations="30", tolerance="1e-5", threshold="1e-5")
    inside_tooth.addObject('MeshOBJLoader', name="loader", filename="tooth_coarse.obj")
    inside_tooth.addObject('MeshTopology', src="@loader")
    inside_tooth.addObject('MechanicalObject', src="@loader")

    inside_tooth.addObject('UncoupledConstraintCorrection', )
    inside_tooth.addObject('SurfacePressureForceField', pressure="5000.0", pulseMode="true", pressureSpeed="2000.0")
    inside_tooth.addObject('UniformMass', vertexMass="0.0")
    inside_tooth.addObject('MeshSpringForceField', name="Springs", stiffness="5000", damping="4")

    visu = inside_tooth.addChild('Visu')

    visu.addObject('MeshOBJLoader', name="meshLoader_0", filename="tooth_closed.obj", handleSeams="1")
    visu.addObject('OglModel', name="Visual", src="@meshLoader_0", color="0.5 1.0 0.5 1.0")
    visu.addObject('BarycentricMapping', input="@..", output="@Visual")

    triangle_surf = inside_tooth.addChild('TriangleSurf')

    triangle_surf.addObject('MeshOBJLoader', name="loader", filename="tooth_coarse.obj")
    triangle_surf.addObject('MeshTopology', src="@loader")
    triangle_surf.addObject('MechanicalObject', src="@loader")
    triangle_surf.addObject('TriangleCollisionModel')
    triangle_surf.addObject('LineCollisionModel')
    triangle_surf.addObject('PointCollisionModel')
    triangle_surf.addObject('BarycentricMapping', input="@..", output="@.")


    outside_tooth = root.addChild('Tooth')

    outside_tooth.addObject('EulerImplicitSolver', rayleighStiffness="0.1", rayleighMass="0.1")
    outside_tooth.addObject('CGLinearSolver', iterations="30", tolerance="1e-5", threshold="1e-5")
    outside_tooth.addObject('MeshOBJLoader', name="loader", filename="tooth_open_coarse_no_approximal_inverted.obj", scale="1.2")
    outside_tooth.addObject('MeshTopology', src="@loader")
    outside_tooth.addObject('MechanicalObject', src="@loader")

    visu2 = outside_tooth.addChild('Visu2')

    visu2.addObject('MeshOBJLoader', name="meshLoader_1", filename="tooth_open_coarse_no_approximal_inverted.obj", handleSeams="1", scale="1.2")
    visu2.addObject('OglModel', name="Visual2", src="@meshLoader_1", color="0.5 0.5 0.5 1.0")
    visu2.addObject('BarycentricMapping', input="@..", output="@Visual2")

    triangle_surf2 = outside_tooth.addChild('TriangleSurf2')

    triangle_surf2.addObject('MeshOBJLoader', name="loader", filename="tooth_open_coarse_no_approximal_inverted.obj", scale="1.2")
    triangle_surf2.addObject('MeshTopology', src="@loader")
    triangle_surf2.addObject('MechanicalObject', src="@loader")
    triangle_surf2.addObject('TriangleCollisionModel')
    triangle_surf2.addObject('LineCollisionModel')
    triangle_surf2.addObject('PointCollisionModel')
    triangle_surf2.addObject('BarycentricMapping', input="@..", output="@.")

Is it feasible to simulate this with the SOFA framework?
I am new to physics simulation and the SOFA framework. Could you guide me through a possible implementation?

Thank you!
Here are the OBJ files I used:
I am using SOFA v24.06

[hugtalbot]

Hi @nnistelrooij

I apologize for the tremendous delay of this reply.
For this registration topic, I would recommend to take a look at the Registration plugin. You can find an associated example : ICPRegistration_ShapeMatching_Engine.scn

Screencast.from.2025-10-02.07-54-55.webm

I hope this helps

[github-actions[bot]]

⚠️ ⚠️ ⚠️
@nnistelrooij
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding