Accuracy of a new elastomeric impression material for complete-arch dental implant impressions

AIM: The aim of the present study was to assess the accuracy of multi-unit dental implant casts obtained from two elastomeric impression materials, vinyl polyether silicone (VPES) and polyether (PE), and to test the effect of splinting of impression copings on the accuracy of implant casts. METHODS: Forty direct impressions of a mandibular reference model fitted with six dental implants and multibase abutments were made using VPES and PE, and implant casts were poured (N = 20). The VPES and PE groups were split into four subgroups of five each, based on splinting type: (a) no splinting; (b) bite registration polyether; (c) bite registration addition silicone; and (d) autopolymerizing acrylic resin. The accuracy of implant-abutment replica positions was calculated on the experimental casts, in terms of interimplant distances in the x, y, and z-axes, using a coordinate measuring machine; values were compared with those measured on the reference model. Data were analyzed using non-parametrical Kruskal-Wallis and Mann-Whitney tests at α = .05. RESULTS: The differences between the two impression materials, VPES and PE, regardless of splinting type, were not statistically significant (P>.05). Non-splinting and splinting groups were also not significantly different for both PE and VPES (P>.05). CONCLUSIONS: The accuracy of VPES impression material seemed comparable with PE for multi-implant abutment-level impressions. Splinting had no effect on the accuracy of implant impressions

Dimensional accuracy of double poured casts obtained from extended pour alginate impressions: An in vitro study

Background: A new generation of smart alginates have been developed claiming to have good dimensional stability and deformation resistance. However, there is a lack of sufficient scientific evidence in this regard. Aim: This study aims to evaluate the dimensional stability of casts generated from first and second pour of two different types alginate purported to allow multiple pour and remain dimensionally stable after storage. Methodology: Forty impressions were made of a maxillary dentulous model (standard die), using two types of alginate (Hydrogum 5.0, Cavex Colour change). Two sets of casts were generated from 10 impressions of each type of alginate immediately. Ten impressions of each type of alginate were stored wrapped in damp paper towel and stored in zip-locked bags, and two sets of cast were generated after 24 h. Casts were scanned with a three dimensional model scanner and compared with standard die. Results: No significant difference was found between standard die and second poured casts of both alginates after immediate pouring. A significant difference was found between standard die and second poured casts of both alginates after 24 h. However, percentage dimensional change was within clinically acceptable limits. Conclusion: Clinically acceptable casts can be generated by the double pouring of new generation alginates. However, for better results casts should be poured immediately