Hi there!
Oh implants. I am missing my right, front, canine tooth (the one adjacent to the 2 front teeth)as a genetic anomaly and I'm currently in the process of getting an implant. Since your missing teeth are in the back, lower jaw, you'll probably have a slightly easier procedure than I will.
The only issue with implants that I'm aware of is implant failure (the post doesn't affix to the bone or is rejected for some reason), and this does happen in a small percentage of people, but it's more likely to be an issue if you have an implant in the front of your mouth where the bone is thinner. Implant success in the molars are very high.
The procedure for implants is as follows: bone graft (typically only for front teeth, so you'll skip this), then a hole is drilled and a titanium post is inserted into the hole drilled into your jawbone and is then sutured and allowed to heal and allow bone regrowth around the post for 3-6 months. After 3-6 months, a tooth crown is attached to the top of the titanium post and it looks like a normal tooth (or as my dentist says "it'll be the strongest tooth in your mouth!" total time is 3-8 months, depending on variables such as type of tooth being replaced, the amount of teeth being replaced, and whether or not you require a bone graft. The information I'm relaying is from a recent consultation with an oral surgeon who will be placing my implant, but I am not a dentist nor am I a dental expert.
Hope this helps!