How is the number of implants decided?

In this video, answering a question from Dr. Dt. Gürcan Çetin, Dr. Dt. Kıvanç Türkoğlu explains why full-arch fixed bridges sometimes use four implants and sometimes five, six or more. This article summarises the video and explains how the number is chosen.

What the video covers

• How bone thickness, height and internal structure affect the number of implants, using the comparison of a hard outer shell and a more porous interior.
• Why more implants may be added for support when the implant length that can be placed is limited.
• How the teeth in the opposing jaw and the number of teeth planned in the bridge affect the decision.
• Why, in a plan with few implants, losing one implant later can affect the whole bridge, and how an extra implant can act as reserve support.

Is there one right number?

There is no single number of implants that suits everyone for a fixed bridge in a jaw without teeth. Research shows that plans using four to six implants can work well in suitable patients. The number chosen depends on the person's bone and what they expect from the bridge.

Planning therefore starts by deciding how many teeth the bridge will have and where they will sit, before choosing implant positions. Which teeth show when smiling and which foods the person wants to chew comfortably are also part of this discussion.

Bone volume and quality

A CT scan helps measure bone width and height and assess its structure. The outer layer of the jawbone is hard and the inside is more porous. If the inner part is wide and the outer layer thin, the bone may hold an implant less firmly. This can be seen especially in people with reduced bone density.

When bone is soft, more implants may be used to spread the load over more points. When bone volume is limited, the need for additional procedures is discussed first.

Implant length and position

The load an implant can carry depends on how long and wide it is within the bone. If the sinus or the nerve canal do not allow long implants, the number may be increased to add support. Short implants can be used in some cases, and the load they will carry is taken into account in planning.

An even spread of implants along the jaw also matters. Angled implants at the back extend the support of the bridge further back.

The opposing jaw and biting force

Natural teeth or a fixed bridge in the opposing jaw can mean higher biting force. If more teeth are wanted in the bridge, for example including back molars, extra implants may be needed to carry them.

Night-time clenching or grinding also increases the load. In that case both the number of implants and the design of the bridge are planned accordingly.

What an extra implant means

In a four-implant plan, if one implant is lost later the remaining implants may not support the bridge well enough. Use of the fixed bridge may then be interrupted until a new implant is placed and healed.

In plans with five or six implants, losing one implant does not always affect the whole bridge. Still, more implants also mean more surgery and more areas to clean. The decision is made after discussing benefits and limitations together. The wider context is in the All-on-4 and All-on-6 section.

Frequently asked

Are more implants always better?

Not always. The number is chosen according to bone, implant length and biting force. More implants than needed means extra surgery and more areas to clean.

Does the number of implants change how comfortable the bridge feels?

With well-planned, healthy implants, comfort depends more on the design and fit of the bridge than on the number of implants.

Who decides on the number?

The surgeon and the clinician who makes the bridge decide together, based on the examination and the CT scan.

Related section and videos

• Section on the expertise page: All-on-4 and All-on-6 (fixed teeth on implants)
• Can fixed temporary teeth be fitted in the same session as implants?
• What is All-on-X treatment?
• How long do implant and bridge treatment take?
• What is a dental implant and what are the stages of treatment?

This information is for general guidance and does not replace an examination. Rapidly spreading facial swelling or difficulty swallowing or breathing is an emergency. Go to a hospital emergency department.