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

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.

The BMF may minimise tooth displacement, saving time and improving occlusion.

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 α (right maxillary molar), β (left maxillary molar), α' (right mandibular molar) and β' (left mandibular molar) were calculated by the law of cosines. Data were submitted to Kruskal-Wallis (5% significance).

No difference was observed among the groups (p > 0.05). In the intra-group analysis, α was significantly different for groups I, II and III; α', for groups II and IV; β, for all groups; β', for groups III and IV.

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.