Right upper front tooth aches and is numb after lower face and neck lift 6 weeks ago.

A typical facelift does not involve the nerve that gives feeling to the teeth.  Likely this is related to something else.  Sometimes a midface lift or cheek implants involve oral incisions along the upper gum line that may be affecting this nerve.  Best to re visit your plastic surgeon to make sure and consult a dentist that can look for any gum or teeth disease.  Best of luck!

The facial numbness is normal and the tooth ache is unrelated as nerves to the teeth do not travel in the plane in which a facelift is done unless you had intraoral incisions for some reason. Most plastic surgeons do not use those incisions. See a dentist.