What type of correction surgery will I need to re-attach my chin?
The only point I would add to Dr. Wittenberg's answer is that the laceration or surgical approach also appears to have injured the nerve to the muscle that depress the left side of your lip (right side of your photo). This results in that side of your lip riding higher when you smile. This likely cannot be repaired but if the asymmetry bothers you very conservative Botox can be used in your right lip depressor muscles to improve symmetry. I hope this information is helpful for you.
Stephen Weber MD, FACS
Denver Facial Plastic Surgeon
The loss of the muscle attachment will give the appearance you have now. I'd there remains some muscle near the teeth side of the area, it can be repositioned. If not, one needs to try to attach the muscle with direct bone contact.