They are pretty hardy and new growth will be forthcoming soon. Of course any damaged plant bits will remain.
Here is an article on determining the extant of damage by checking the cambium by the use of a sharp knife.
»
www.canadiangardening.co ··· is-dead/Decent article of what to do about winter damaged plants.
»
www.rutgersln.com/nurser ··· -damage/Although an article on grafting, with a number of images that shows what healthy cambium looks like. That is what you want to look for.