Comparison of the accuracy of conventional and digital impressions for mobile teeth

Objectives: Periodontal prosthesis is essential in the treatment of severe periodontal disease. How to make a precision final impression for the mobile teeth is an important issue. The aim of this in-vitro study was to evaluate the accuracy of conventional and digital impressions for mobile teeth.
Methods: A lower partial teeth model was used as a testing model. The testing model teeth with various mobility and the degree of tooth mobility was guided by Miller classification. Two polyvinyl siloxane PVS (Take-1, Kerr; Aquasil, Dentsply ) were used with two impression methods (one-step dual phase/mono phase). An intra-oral scanner (IOS) (3-shape Trios) and a Lab scanner (3-shape D850) were used as digital impression .The buccal displacement and distal displacement data were analyzed with ANOVA, p<0.05.
Results: The IOS had a largest significant difference (189μm, p<0.05) of buccal displacement in the 0 degree mobility group. The IOS had a largest difference (96μm, p>0.05) of buccal displacement in the 1 degree mobility group. There were no difference of buccal displacement among the two PVS (76μm) and Lab scanner (52μm) in the 1 degree mobility group. The two PVS had a largest significant difference (257μm, p<0.01) of buccal displacement in the 2 degree mobility group. There was significant difference of distal displacement in the two PVS between the mobile tooth sections.
Conclusions: Mobility and migration are signs of periodontitis. The conventional and digital impressions are significant influence by teeth mobility. If persistence of mobile teeth is found, the final impression is prohibited.