The centre lines of the upper and lower teeth should line up with the middle of the face. The upper midline can be off-centre because of uneven crowding of the teeth or a shifted bite. The lower midline can be off-centre in relation to the middle of the face because the lower jaw has developed asymmetrically, or again because of crowding or an incorrect bite. In general, when the cause of an off-centre midline lies in an asymmetry of the jaw, moving the teeth may not be able to disguise the problem, because the cause lies in the underlying bones. If the problem is due to displaced teeth or a shifted bite, the centre line can in all likelihood be corrected with orthodontic treatment alone. An unequal number of teeth on the left and right – whether inherited or because a tooth that couldn't be saved was extracted in the past – can also make it impossible to centre the teeth. In some cases the midlines are off because the teeth on the left and right are different sizes – for example, when one upper lateral incisor is smaller than usual, which is often inherited.
This answer is for general information. Your own case needs an examination by an orthodontist.