Fabrication of Dental Stone Model Samples

For the fabrication of study samples, two maxillary jaw teeth set dental stone model was used. The maxillary second molar (Dentona^® Esthetic-Base^® gold, Dentona AG, Dortmund, Germany) was prepared in the model (the first molar was cut) to receive a circumferential clasp with the desired undercut (Figure 1). The maxillary jaw model was surveyed and an undercut of 0.25 mm on one model and 0.50 mm on the other were created. Occlusal rests (2.5 mm long, 2.5 mm wide, and 2 mm deep) were placed mesially. The prepared molar models were duplicated with silicon impression material (Dublisil, Dreve Den-tamid GmbH, Unna, Germany). The impressions were poured into resin material (RHINO ROOCK, DB Lab Supplies Limited) to fabricate 42 molars models: 21 with a 0.25 mm undercut and 21 with a 0.50 mm undercut [23 (link)].