For just as in one body we have many members, and all the members do not have the same function, so we who are many are one Body in Christ, and individually members one of another.
When Romans mentions "in Christ" it's talking about an organic union. We were first born in Adam, but were reborn and transplanted into Christ. We're in union with the Lord and the other brothers and sisters of Christ.
In this organic union, there's life!! It is sooooo unlike dentures--dentures may be put into my mouth, but there is no life in it nor organic union...ewww...PRAISE THE LORD WE AREN'T DENTURES!!!! We were born again to abide in Him and have Him abide in us to remain in this organic union!!!