An Evaluation of Retention of Complete Denture Bases Made with a “Modified Single-stage Impression” Technique Using a Heat-moldable Tray

Abstract

Aim: Although most dental schools teach complete denture definitive impression techniques consisting of secondary impressions in border-molded custom impression trays, it has been found that later, graduates in clinical practice abandon this step because of its complexity and attempts to seek easier alternatives. To simplify two-stage techniques, single-step border molding with elastomeric impression materials and light-cured resin materials has gathered acceptance among clinicians. The study aims to evaluate the retention of record bases made with a modified single-stage impression technique that uses elastomeric impression material in a heat moldable tray with modeling compound as material for border molding. Settings and Design: This was an in vivo preliminary cohort study. Materials and Methods: Thirteen completely edentulous patients requiring complete dentures were included in the study. A traditional two-stage impression was made using custom trays fabricated over diagnostic casts and further border molding done with a modeling compound, and the final impression was made to use zinc oxide–eugenol impression material. Additionally, a modified single-stage impression technique using heat moldable impression trays was made. Master casts from each technique were made, and further record bases were made on each master cast. Wire loops were adapted on the palatal aspect of record bases. The retention of each record base was evaluated using a force gauge. Statistical Analysis: The Kolmogorov–Smirnov test was used to analyze the normality of variables and later Wilcoxon signed-rank test was applied. Results: The double-stage technique exhibited retention values in the range of 0.6–66.7 units, whereas the single-stage technique showed a range of 0.15–78.55. The tests showed no significant difference between double-stage and single-stage techniques (P > 0.05). Conclusions: The single-stage technique using heat moldable trays with elastomeric impression material and modeling compound as a material for border molding can produce denture retention compared to the conventional technique that uses a two-step impression technique. The use of the modified single-stage technique can additionally save an extra appointment for patients, although it is better to use such a technique as an advanced impression technique and not as a training technique for beginners or students, as the material cost is substantially higher than the conventional two-stage technique.

Keywords

• complete denture retention
• impression techniques
• single-stage impression