• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.3
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• pp.142-148
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• 2024

Purpose: The purpose of this study was to investigate the accuracy of digital mounting with occlusal scans in the interocclusal record for a full-mouth fixed prosthetic treatment condition. Materials and Methods: The entire maxillary teeth were prepared in a dentiform model and attached to an articulator in maximum intercuspation. Temporary crowns were fabricated and occlusion was adjusted. After scanning the arch with tooth preparation, digital mounting was performed using an occlusion scan of the anterior or posterior teeth areas. The accuracy of the positioned jaw relation was evaluated three-dimensionally through positional deviation and angular error of the occlusal plane. Afterwards, the same procedure was repeated on the partially edentulous model to evaluate the accuracy of digital interocclusal record. Kruskal-Wallis test and Mann-Whitney U test were used for statistical analysis, and the significance level was set at 0.05. Results: There was no significant difference in the positional error at the center of the arch in the digitally established jaw relation depending on the scan area used and remaining tooth conditions (P = 0.53). The angular error of the occlusal plane was larger when the anterior teeth were used as the overlapping area, and a smaller error value was observed when both posterior teeth were used as the overlapping area (P < 0.001). Conclusion: The use of bilateral posterior occlusal scans is recommended when digitally mounting the jaw relation established with temporary teeth during full-mouth fixed prosthetic treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.4
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• pp.253-261
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• 2024

Purpose. This study aimed to evaluate the effect of shell thickness on the fracture strength of provisional crowns fabricated by indirect-direct technique. Materials and methods. The study simulated the application of a provisional crown on a maxillary first molar implant abutment. A titanium metal die was milled by replicating a ready-made implant abutment. Using CAD software, shells for provisional crown was designed with varying thicknesses of 0.5 mm, 1.0 mm and 1.5 mm with different internal spaces for relining. These shells were 3D printed using photosensitive liquid resin and relined with PMMA resin to fabricate provisional crown specimens using indirect-direct technique. Ten specimens per each group were prepared. Fracture strength was measured by applying compressive loads vertically to the occlusal center of the specimens at a crosshead speed of 1.0 mm/min using a universal testing machine, and the maximum load value (N) at fracture was recorded. To compare the fracture strength between experimental groups, a one-way ANOVA followed by Tukey's post hoc test was conducted (α=.05). Results. The fracture strength was observed in the following order: Group 1.5 (1504.5 ± 141.30 N), Group 1.0 (1420.2 ± 182.05 N), and Group 0.5 (1083.1 ± 178.90 N). Group 1.5 was not significantly different from group 1.0, but was significantly different from group 0.5, and group 1.0 was also significantly different from group 0.5. Conclusion. The fracture strength of provisional crowns fabricated by the indirect-direct techniques were significantly different depending on the thickness of the shell. The fracture strength of the indirect-direct method was significantly lower when the shell thickness was 0.5 mm compared to 1.0 mm and 1.5 mm. This finding indicates that the shell should not be too thin when fabricating provisional crowns using the indirect-direct technique.