Accuracy Of Dentures Research Articles

Accuracy of repaired maxillary dentures from two different repairing techniques: In vitro study

BackgroundDenture fracture is a common problem with acrylic dentures. The fractured denture can be repaired using various techniques such as self-cure acrylic resin acrylic resin and fiber-reinforced acrylic resin. PurposeThe purpose of this study was to compare the accuracy of dentures repaired with self-cure acrylic resin and fiber-reinforced acrylic resin processed using two different techniques (long-cure and microwave processing). Materials and methodsA total of 20 maxillary complete dentures were processed with two techniques; heat (long cycle) processing (10 dentures) and microwave processing (10 dentures). The maxillary cast and denture surface were scanned with Medit intraoral (Medit i700, Medit, South Korea) and STL files were created. Then, the dentures were sectioned at the midline and repaired using self-cure acrylic resin and fiber-reinforced acrylic resin and scanned with Medit intraoral. Finally, adaptation deviations were analyzed from computer software (Geomagic Control X, 3D Systems Inc., USA). The adaptation deviations in each group (long cure and microwave) were compared using an Independent T-test. Two-way ANOVA was done to see whether curing techniques and repairing methods affect the accuracy of repair. A P-value of 0.05 was considered significant. ResultsThe adaptation deviation was slightly higher in the fiber-reinforced acrylic resin group (0.565 ± 0.093) than in the self-cure acrylic resin group (0.536 ± 0.066). However, there was no statistical difference in the adaptation deviations of repaired dentures with self-cure acrylic resin and fiber-reinforced acrylic resin in the long-curing (P-value 0.245) and the microwave (P-value 0.638). Similarly, the adaptation deviation was slightly higher in the long-curing group (0.577 ± 0.075) than in the microwave group (0.524 ± 0.079). However, there was a statistically significant difference in the adaptation deviation of repaired dentures between long-curing and microwave techniques with self-cure acrylic resin (P-value 0.016) but no difference in fiber-reinforced acrylic resin (P-value 0.127). The result of Two-way ANOVA shows that there is no statistically significant interaction between curing techniques (long curing and microwave) and repairing methods (self-cure acrylic resin and fiber-reinforced acrylic resin) for adaptation deviations (P-value 0.646). However, the curing techniques show statistically significant differences (P-value 0.039). ConclusionAcrylic dentures can be repaired with self-cure resin or fiber-reinforced self-cure resin using various processing methods. The accuracy of the denture after repair is unaffected by the repairing method (self-cure acrylic resin and fiber-reinforced acrylic resin) but the accuracy of the denture after repair is affected by the curing techniques (long-curing and microwave). In self-cure resin, the microwave processing showed higher adaptation deviation and less accuracy, whereas the long-curing processing showed lower adaptation deviation and high accuracy.

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.