Comparative Analysis of Dimensional Accuracy of Two Types of Silicone Impression Materials: ...

Conclusion: Optosil is more accurate in registering inter-abutment distance than Elite-HD, so Optosil is preferred for fixed partial denture impressions. Since Elite-HD showed more accuracy in C measurements than Optosil, it is preferred for single crown impressions. 
Source: Journal of Dental Materials and Techniques - Category: Dentistry Source Type: research