A method includes determining the following for each point in a second intraoral scan based on a comparison of a first intraoral scan to the second intraoral scan: whether a surface normal at the point is co-directional with a viewing direction associated with the first intraoral scan, wherein points in the second intraoral scan that have a surface normal that is co-directional with the first viewing direction are back-face points; and whether the point is behind a corresponding point in the first intraoral scan, wherein points in the second intraoral scan that are not behind corresponding points in the first intraoral scan are uncovered points. The method further includes determining a region comprising a plurality of points in the second intraoral scan that are uncovered back-face points, determining that the region satisfies one or more removal criteria, and removing the region from the second intraoral.