The influence of double flask investing on tooth displacement in dentures processed by microwave irradiation

Abstract

Objective: This study evaluated the influence of the bimaxillary flask (BMF) and two different investing materials on first molar inclination in dentures processed by microwave irradiation. Background: The BMF may minimise tooth displacement, saving time and improving occlusion. Methods and materials: Forty pairs of dentures were randomised into four groups: stone wall in monomaxillary flask; silicone wall in BMF; stone wall in BMF; acrylic resin retentions and silicone in BMF. Dentures were processed by microwave irradiation. Two referential points were established on tooth surface. A microscope and a digital pachymeter were used to measure the distance between these points, and the angles a (right maxillary molar), b (left maxillary molar), a¢ (right mandibular molar) and b¢ (left mandibular molar) were calculated by the law of cosines. Data were submitted to Kruskal-Wallis (5% significance). Results: No difference was observed among the groups (p > 0.05). In the intra-group analysis, a was significantly different for groups I, II and III; a¢, for groups II and IV; b, for all groups; b¢, for groups III and IV. Conclusion: First molar inclination was similar for monomaxillary and BMFs. The use of stone or silicone as investing materials presented the same effect on tooth inclination.