Local anaesthetic still not wearing off...?

I had two wisdom teeth pulled under general anaesthetic last Thursday - a week ago. They must have injected a fair bit of local anaesthetic into my jaw too because it was numb for ages after the op. And now, seven days later, I still have very little feeling in my lower lip and chin. I am worried that I have permanent nerve damage from the tooth extraction. Has anyone else experienced numbness lasting this long after an operation? I will call my dentist in the morning but it's nearly midnight here in the UK so there's not much I can do right now...!