Influence of different flask systems on tooth displacement and framework misfit in mandibular fixed implant-supported complete dentures.

Purpose: To evaluate the influence of different metallic flask systems for acrylic resin denture processing on tooth displacement and framework misfit of mandibular fixed implant-supported complete dentures.

Methods: Standard mandibular implant-supported complete dentures in five implants were waxed and randomly assigned to three groups: G1 - conventional flask, G2 - double flask, and G3 - occlusion flask. Framework misfit in all the implants and the linear distances between teeth (I-I - incisor-to-incisor; P-P - premolar-to-premolar; M-M - molar-to-molar; RI-RM - right-incisor-to-right-molar; and LI-LM - left-incisor-to-left-molar) were measured before and after denture processing using an optical microscope. Dentures were processed by hot water curing cycle (9h/74°C). Collected data were analyzed by paired Student's t-test and one-way ANOVA (α=0.05).

Results: All the measured distances presented changes in tooth displacement after denture processing. However, the M-M distance for G1 (p=0.003) and the P-P (p=0.042) and LI-LM (p=0.044) distances for G3 showed statistically significant differences. Differences between the flask systems were not statistically significant. Statistically significant differences in the framework misfit due to denture processing were found for all the implants and groups, with the exception of right median implant for G2 and right distal implant for G3. A comparison of the flask systems found statistically significant differences in which G1 presented an increase in the misfit values and G2 and G3 a decrease.

Conclusions: Different flask systems did not cause significant changes in tooth displacement. Frameworks misfit values were influenced by the different flask systems. The conventional flask presented an increase in the framework misfit, while the experimental flasks showed a decrease.