The multi-center randomized shortened dental arch study (RaSDA) intended to compare the two different treatment options for bilaterally shortened dental arch cases. Patients received either a precision attachment retained removable dental prosthesis (RDP) for molar replacement or were treated following the shortened dental arch (SDA) concept without molar replacement. Aim of the present analysis was to evaluate tooth movements and changes in tooth morphology.
10 randomly selected cases, five each of the RPD and the SDA group, were analyzed. Inclusion criterion for this analysis was the presence of complete sets of master-casts in sufficient quality (baseline, 3-Year follow-up, 5-Year follow-up). First, the master-casts were inspected visually. Second, the master-casts were digitized (digiSCAN L, Amann Girrbach, Pforzheim, Germany) and CAD surface models created (Surfacer 10.6, Imageware Inc., Ann Arbor, Michigan, USA; geomagic studio 9.0, Geomagic Inc., Research Triangle, NC, USA). Data of the baseline master-cast were used as reference while 3-year and 5-year data was superimposed to the reference. Differences were analyzed three-dimensionally (3D) over time regarding movements of teeth and variations of tooth morphology.
Using the 3D-analysis of master-casts, 3 cases showed movements of teeth and 9 cases showed wear compared with baseline. While applying visual inspection, tooth movements were recognized precisely, the computerized analysis using digitizing, alignment and 3D-measurments showed superior results in the detection of wear.
Precise 3D-analysis of digital data acquired from master-casts produced at different points in time is challenging regarding the rigorous alignment requirements for data sets being in different measurement coordinate systems into a conjoint coordinate system applicable for data analysis. Using the 3D-analysis, movement of teeth and wear can be assessed precisely over time. However, the procedure is based on specific hard- and software and is time-consuming.
Keywords: Clinical trials, Prosthodontics and Wear