Start with the restoration you need
Both approaches can support a full replacement arch. The number of implants is only one part of the design. The position of the implants, the support beneath them, the bridge material and the way your teeth meet all matter. Begin by asking why the proposed approach fits your mouth.
The role of bone and anatomy
A scan can help the clinician assess bone and nearby structures. Four and six implant positions place different demands on the available anatomy. Additional implant sites may be useful in one case and inappropriate in another. If grafting is discussed, ask what it aims to achieve and how it changes treatment stages.
Consider what can be preserved
A full-arch proposal should explain why any remaining teeth are being removed. Some teeth may have a poor prognosis; others may be treatable. Understand the alternatives, including retaining teeth, a removable prosthesis or a different implant design. Irreversible treatment should follow a clear explanation of the reasons.
Compare complete proposals
Compare the surgery, temporary teeth, final bridge, materials, appointment stages and maintenance. A higher implant count does not tell you whether two quotes cover the same work. Ask how the bridge can be cleaned, how components can be repaired and what happens if an implant does not heal as expected.
Questions for your consultation
Ask why each implant position is proposed, whether you will have fixed provisional teeth, how healing affects the final fitting and what maintenance is needed. The useful comparison is between appropriate plans for your clinical situation, not a universal ranking of four versus six.