Upper jaw or lower jaw: why the number often differs
Your two jaws are built differently. That's why the same person can end up with six implants on top and four underneath.
Medically reviewed by Dt. Hüseyin Yavuz Özbek, implant surgeon · Updated October 2026Upper jaws usually have softer, less dense bone and the sinus sits above the back teeth, so many dentists prefer six implants there when bone allows, or angle the back implants of a four-implant plan in front of the sinus. Lower jaws usually have denser bone at the front, between the two nerves, so four or five implants are often enough. Your scan decides for each jaw separately.
The upper jaw
What makes it different
- Bone is usually softer and less dense
- The sinus sits above the back teeth, and after tooth loss it often leaves little bone height there
- An upper bridge covers a wider arch
How plans adapt
- Six implants, when there's enough bone, to share the load
- Four, with the back implants tilted to stay in front of the sinus
- A sinus lift, or zygomatic implants when bone is very thin
Research backs the caution. A 2024 review of 53 upper-jaw studies found implant and bridge survival were similar with four or six implants, but bone loss around the implants was higher with four. The authors suggested that, where the bone allows, more implants may reduce complications in the upper jaw.
The lower jaw
What makes it different
- Bone at the front, between the two chin nerves, is usually dense
- A nerve runs inside the jaw further back, limiting where implants can go
How plans adapt
- Four implants, with the back ones tilted in front of the nerve, are common
- Five, or six where bone further back allows
In the 2018 review of 93 studies, the most common choice in the "five or more" group was six implants for upper jaws and five for lower jaws. In the "fewer than five" group it was four for upper jaws and three or four for lower jaws. That pattern reflects the bone, not a rule.
Both jaws at once
- Plans are made separately. Six on top and four underneath is a perfectly normal result.
- The bite matters. Two full arches bite against each other, which is one reason dentists think about load and grinding.
- Ask for both in writing. How many implants per jaw, which brand, and why.
Being treated in Turkey? Treating both jaws usually fits into the same two trips. See allon6turkey.co.uk for how the trips work.
Common questions
Can I have All-on-6 on top and All-on-4 on the bottom?
Yes. Each jaw is planned on its own. It's common for the plans to differ because the bone differs.
Why is the upper jaw harder to treat?
The bone is usually softer, so implants can be less firmly held at first, and the sinus limits how much height there is at the back. Both can be planned around, but they affect the choice.
Is the lower jaw easier?
Often, at the front. The bone between the two chin nerves is usually dense. Further back, the nerve inside the jaw limits where implants can go.
Sources
- Sharaf et al. (2024), Heliyon — Four or six implants for maxillary fixed prostheses: systematic review and meta-analysis
- Polido et al. (2018), Clinical Oral Implants Research — Number of implants placed for complete-arch fixed prostheses: systematic review and meta-analysis
- Nobel Biocare — All-on-4® treatment concept
Checked October 2026. Where we give our own view as a clinic, we say so.
Only a scan can settle it.
Send us an X-ray or scan if you have one. A dentist will tell you which option suits your bone, and say so honestly if neither is the right step.