Influence of different metal flask systems on tooth displacement in complete upper dentures

Abstract

To verify the occurrence of tooth displacement in dentures processed by moist hot-polymerisation using traditional and experimental metal flask systems. Waxed complete dentures were randomly assigned to three groups (n = 10), including traditional (TF) and experimental flasks (DF and HHF). Metal pins were placed at the incisal edge of maxillary central incisors (I), buccal cusp of first premolars (P) and mesiobuccal cusp of second molars (M). Transversal (I-I, P-P and M-M) and anteroposterior (LI-LM and RI-RM) distances were measured before and after denture processing using an optical microscope. The dentures were processed by hot water curing cycle (9 h/74 °C). Collected data were analysed by anova, Paired Student's t-test and Holm-Sidak method (p < 0.05). All measured distances demonstrated contraction after polymerisation, except for LI-LM in TF and RI-RM in DF and HHF. Statistically significant differences were found between the distances P-P for DF and HHF, and M-M for all groups. Comparison among flask systems revealed statistically significant difference in the P-P distance for the TF and HHF. Different flask systems did not cause variation in tooth displacement during denture processing, with the exception of P-P distances for the TF and HHF. There is no evidence that different metal flask systems would promote tooth displacement of clinical significance.