For how long do dental onlays/crowns normally hurt?

Hurt. Generally trauma to the tooth from cementation can last 4-6 wks getting better week by week. If you feel your bite is not quite right the tooth will be sensitive until the bite is adjusted. If the sensitivity to hot/cold lasts more than 10 sec or the tooth spontaneously starts to hurt see your dentist to have the tooth evaluated for a nerve problem. Hope this helps.