[The comparison analysis of the line measurements between plaster and virtual orthodontic 3D models]

The aim of the research was to answer the question: can 3D virtual models replace plaster models and can they improve the orthodontic treatment process and the organization of work in the orthodontic practice.

The comparison analysis included diagnostic plaster and 3D virtual models of 25 patients who met the following criteria: (1) malocclusion; (2) no prior orthodontic treatment; (3) sound permanent dentition up to T1, T2 or T3; (4) at least three contact points in centric jaw relation of dental arches. Types of measurements carried out: (1) mesio-distal tooth width; (2) measurements of distances with points situated in the opposite sides of the upper and lower arch; (3) spee's curve depth; (4) measurements of distances of overlap of incisors in vertical and horizontal planes.

Repeatability of the mesio-distal width measurements carried out on plaster models by means of digital caliper (method 1) and vernier caliper (method 2) is similar. The lowest is the repeatability of virtual 3D models (method 3). The highest repeatability in the area of measurement of the dental arches width can be noticed in method 2. Measurements of the curve of Spee's depth, overbite and overjet performed by means of three methods produce close level of repeatability. Reproducibility of the measurements by means of all three methods is on the same level.

Technology of 3D virtual models needs improvement, however as the models are broadly applied worldwide it may be stated that for the time being they are advantageous option for plaster models.