My son 15

My son 15 year old has a tooth still up in his gum,his fang sorry don’t know the real name. He has a milk tooth still in place below it. He has had an appointment at the nhs orthodontist who has said he needs to go in for surgery and have the tooth in his gum removed, the milk tooth and another tooth on the other side and have a brace because his teeth are all pushing forward and he he has an over bite. The orthodontist also suggested removing the baby tooth and pulling the other tooth down with a chain, but decided against it and said the extraction of the tooth would be easier. I would like to know how successful would the proceedure of pulling the tooth down be and should I be pushing for this treatment rather than three teeth being extracted? Also if I was to take him somewhere else for a second opinion would it have to be a dental hospital rather than a dentist.