Teeth are very strong but can break, as enamel can chip or break when heavy forces are concentrated especially on thin edges like the front teeth. If a tooth fractures and there is no pain or temperature sensitivity it may indicate that the fracture – whether of tooth, or of filling – is probably not particularly deep. If it will be a while before you can see your dentist to repair the damage, a first aid measure is to buy some orthodontic wax at the pharmacy and place it on the sharp edge so you don’t irritate the tongue or cheek.
If on the other hand there is pain and substantial temperature sensitivity it may indicate a deeper fracture and should be seen by the dentist as soon as practical. Sometimes a temporary filling paste available at the pharmacy can be placed to gain some relief, and over the counter pain relievers may be beneficial.