A digital orthodontic treatment planning system provides a practitioner with digital representations of at least a part of a tooth of a patient and at least part of a coupling matrix within a three-dimensional environment. By interacting with the system, orthodontic practitioners are able to visualize a coupling matrix that results from a specific orthodontic appliance position relative to a tooth of the patient's dental arch. The digital representation of the coupling matrix represents a substance, such as a cured adhesive, that connects an orthodontic appliance to a tooth of a patient. The system determines a thickness of at least a portion of the coupling matrix. In one embodiment, the system indicates the total thickness via a thickness map, such as a color-coded thickness map. In another embodiment, the system indicates a deviation from a baseline thickness via a thickness map.