Efficacy of conventional and experimental techniques for denture repair

This study investigated the efficacy of one experimental and three conventional techniques for denture repair. Forty maxillary dentures were constructed in dental stone casts duplicated from an edentulous copper-aluminium maxillary master cast. Two groups of 20 dentures each were prepared with Lucitone 199 (water-bath, 8 h/74 degrees C) or Acron MC (microwave, 3 min/500 W) denture base materials processed in gypsum moulds. The 40 dentures were all separated sagittally in the middle. After that, five dentures of each denture base material were repaired with one of the four following techniques: L (Lucitone 199, water-bath, 8 h/74 degrees C, gypsum mould), A (Acron MC, microwave, 3 min/500 W, gypsum mould), AR (Acron MC/R, autopolymerized, 60 psi/45 degrees C/15 min) and the experimental technique AS (Acron MC, 1 min/500 W + 1 min/0 W + 1 min/500 W, hard silicone mould). The parameters denture accuracy (DA), horizontal (HC) and vertical changes (VC) of the occlusal plane measured the efficacy of the repair techniques. The DA was determined by weighing a film of silicone impression material set in contact to the tissue surface of the denture seated on the metallic master die. For HC, cross-arch measurements were made among reference marks drilled on the teeth 11, 21, 16 and 26. The VC was obtained by calculating the relative differences in height between similar teeth of each semi-arch (pairs 13-23, 14-24, 15-25 e 16-26). For DA, HC and VC, the percentage differences between the percentage means obtained before and after repair were calculated and grouped for comparisons. Analysis of variance (SuperANOVA) and means compared by Tukey-Kramer intervals (0.05) revealed that AR repair had the best percentage difference value for DA [0.5% (P < 0.05)], while the others were not statistically different [L = 27.2%, A = 28.9%, AS = 21.2% (P > 0.05)]. For HC, there was a statistical difference (P < 0.05) between AR and the other techniques for the tooth pairs, 16-26, 11-26 and 21-16; repairs with AR and AS differed for the 11-21 pair, while those with A and AS techniques differed for the 16-26 pair (P < 0.05). The VC differences were not detected between repair methods (P > 0.05). Denture accuracy was not affected by the interaction of base material-repair technique; repair with AR technique gave the best adaptation; the interaction of base material-repair technique did not affect HC; HC was affected by the repair technique.