Why was one of my implants placed in a single stage while another needed a second surgery?

The surgical method differs because the bone condition differs from site to site. Where the bone is dense and plentiful, a one-stage approach is possible, placing the implant and the connecting post above the gum at the same time. Where the bone is weak or a bone graft was done at the same time, it is safer to use a two-stage approach: the implant is buried under the gum for protection while it fuses with the bone (usually 2 to 6 months), and a second surgery then connects the post. Both methods can be used at different sites in the same mouth, and that is a normal treatment plan.