A computing device for dental impression scan merging includes a model manager configured to generate a first three-dimensional model and a second three-dimensional model, and a merge manager configured to merge the first model and the second model. Each model includes a respective plurality of geometric faces indicative of a respective dental impression of a dental arch of a user. Merging the first model and the second model includes aligning the first model and the second model, removing a geometric face of the first model, selecting a geometry of the second model corresponding with the removed geometric face of the first model, and generating a merged model that includes the selected geometry and the geometric faces corresponding to the selected geometry. The merged model is used to manufacture a dental aligner specific to the dental arch of the user and configured to reposition one or more teeth of the user.