///<summary>Pri or perm tooth numbers are valid. Only locations of perm teeth are stored. This also converts mm to screen pixels.</summary>
private float GetTransX(string tooth_id)
{
int toothInt = ToothGraphic.IdToInt(tooth_id);
if (toothInt == -1)
{
throw new ApplicationException("Invalid tooth number: " + tooth_id); //only for debugging
}
float xmm = ToothGraphic.GetDefaultOrthoXpos(toothInt); //in +/- mm from center
return((WidthProjection / 2f + xmm) * Width / WidthProjection);
}