Generally speaking, it is better to have a failed tooth removed as soon as possible to avoid further damage to the surrounding bone, and to have an implant inserted soon afterwards. Most people’s jaws have finished growing by age 18 so it is possible to have implants at this age but this is something best determined by your dentist. If you are worried about your dentist’s experience, ask what kind of training they have completed in placing implants as even though they are young they may have undergone extensive training. Alternatively contact one of the dental schools in London for advice.