I realise this post is old, but in case someone else needs to refer to it...
"Urtagskrona" is a crown fitted before the provision of a removable partial denture. It may incorporate rest seats or guide planes. It may correct occlusal discrepancies or provide adequate undercuts for various forms of clasps. It may even incorporate precision attachments.
If working in the Swedish dental system, Försäkringskassan has special rules applying to crowns for the support of partial dentures. The usual "Kronregel" is superseded by these rules.