I believe that the Sutton Hoo helmet is Anglo-Saxon and not Viking, Historians believe that it's from the early 7th century and Vikings didn't start raiding England till the late 8th century.

Got my info from the British Museum website: http://www.britishmuseum.org/explore/highlights/highlight_objects/pe_mla/h/helmet_from_sutton_hoo.aspx

Sutton Hoo is Anglo-Saxon and, if you buy Terry Gunnel's theory about space and performance in Anglo-Saxon England and early medieval Scandinavia, intended for ceremonial use moreso than battle.

That said, as far as full-face helmets from the 'viking age,' (whatever that is) are concerned, we don't have any evidence of them existing in the archaeological record, as we have only got three helmets which have been recovered - an intact one in Gjermundbu, and fragments in Tjele and Gotland. The fragments are similar to the Gjermunbju helmet, where there were 'goggles' which protected the nose and eyes, which might be based on earlier Vendel-period helmets, but again, we're not really sure considering we have only three exemplars.

We do know that helmets were used routinely, based on accounts in the sagas and on picture stones, but just what they looked like or what they were made of is, unfortunately, something we don't know for sure.