What are full-arch teeth on four or six implants?
When all the teeth of a jaw are missing, or the remaining ones cannot be saved, a limited number of implants carries a fixed bridge with the whole row of teeth. According to the systematic review for the 6th ITI Consensus Conference (Polido and colleagues, 2018), the most common numbers were: in studies with fewer than five implants, usually four; in studies with five or more, usually six in the upper jaw and five in the lower jaw.
According to Cleveland Clinic, full-arch bridges fixed to implants cannot be removed at home; if necessary, the dentist removes them for maintenance. The process and who it suits are described on our full-arch implants page; this guide focuses on the difference between four and six implants.
How do the two concepts differ?
According to the ITI consensus statement, in most studies with four implants the back implants were tilted backwards, while in most studies with six implants they were parallel. The table summarises the typical differences:
| Topic | Four implants | Six implants |
|---|---|---|
| Implants per jaw | four | usually six |
| Position of the back implants | usually tilted backwards | usually upright and parallel |
| Bone needed | tilted implants can make better use of existing bone | enough bone needed in more places |
| Load distribution | each implant carries a larger share | load spread over more implants |
| Bridge design | usually one piece | one piece or divided |
| Surgery | fewer implants placed | more implants placed |
What do studies comparing four and six implants show?
The review by Polido and colleagues analysed 93 studies, including nine randomised trials, divided into concepts with fewer than five and with five or more implants:
- Upper jaw: With fewer than five implants, 97 per cent of implants and 98 per cent of bridges survived; with five or more, 95 per cent of implants and 98.5 per cent of bridges.
- Lower jaw: With fewer than five implants, 97 per cent of implants and 99 per cent of bridges; with five or more, 95 per cent of implants and 98 per cent of bridges.
The differences were not statistically significant. The authors note limitations, however: 84 of the 93 studies were not randomised, follow-up with fewer than five implants was shorter (a median of 5.5 years), and only survival was examined, not bone loss or technical problems.
A randomised trial with a direct comparison (Tallarico and colleagues, 2016) treated 40 upper jaws with four or six implants placed with a surgical guide and loaded immediately. After five years, 5 per cent of implants had been lost in the six-implant group and 1.25 per cent in the four-implant group, with no significant difference; no bridge was lost. Bone loss around the implants (1.71 versus 1.51 millimetres) also did not differ significantly. The authors consider both concepts predictable in the medium term and call for longer studies.
Polido and colleagues also stress that in the upper jaw, the spread of the implants from front to back matters as well as their number.
What are tilted implants for?
With four implants, the two back ones are usually tilted backwards. According to Polido and colleagues, this shortens the unsupported part of the bridge behind the last implant (the cantilever) and can reduce the need for bone grafting. In 18 studies with two upright front and two tilted back implants in the upper jaw, an average of 97.8 per cent of implants and 99 per cent of bridges survived.
The systematic review by Del Fabbro and colleagues (2012) analysed ten studies with 1,992 immediately loaded implants (966 of them tilted). In the first year, 1.25 per cent of implants were lost, with no difference between tilted and upright; no bridge was lost.
Tilted implants do not replace bone grafting in every case. More in our guides bone grafting before implants and sinus lift.
How do the bone and the jaw affect the decision?
Polido and colleagues describe how bone in the back of the upper jaw is often resorbed; grafting there is predictable but prolongs treatment. In the front of the lower jaw, the bone is usually denser.
According to the ITI’s clinical recommendations, at least four well-distributed implants are recommended for a one-piece fixed bridge. Polido and colleagues do not consider two implants in the upper jaw acceptable and regard three as controversial, because the loss of one implant can lead to the loss of the bridge. The ITI recommends bone grafting when the number or distribution of implants needs to be improved.
The CBCT scan is decisive here: it shows the height and width of the bone and the position of the sinus and nerve canal. How general health affects planning is covered in our guides dental implants with diabetes and smoking and dental implants.
What does the choice mean for care and the long term?
The ITI recommends considering, when choosing the number of implants, how a later loss of an implant would affect the support of the bridge; additional implants can allow a divided rather than a one-piece bridge.
According to Cleveland Clinic, a fixed bridge on implants is brushed with a soft brush, and floss threaders and interdental brushes are used underneath it. The ITI counts enough room for cleaning among the planning criteria. Instructions are in our guide caring for teeth on implants, and the warning signs of inflammation in our guide peri-implantitis.
How is it decided what suits you?
The ITI recommends planning the final teeth first and deriving the surgery from them. Factors include:
- the material of the bridge and whether it is one piece or divided
- appearance, such as lip support and smile line
- the teeth in the opposing jaw and the space available for the bridge
- the volume, quality and anatomical limits of the jawbone
- the distribution of the implants and the length of the cantilever
- enough room for cleaning and maintenance
- the patient’s wishes and cooperation with care
Questions for your examination: Is my bone enough for four or six implants, or is grafting needed? Will my bridge be one piece or divided? How do I travel home with my temporary teeth, and where do the check-ups take place?
What does this mean for treatment in Türkiye?
Fixed teeth on implants usually need two stays: on the first, teeth are removed if necessary, the implants are placed and, depending on your case, temporary teeth are fitted; on the second, after healing, the final bridge is made and fitted. Whether four or six implants are planned changes little about this; bone grafting, on the other hand, can mean a further stay. The process is described in our guide Full-arch implants step by step, and the time with temporary teeth in our guide temporary teeth with full-arch implants.
For a preliminary assessment, send photos and any existing X-rays on WhatsApp to +90 532 363 49 54; during working hours we reply in English within 15 minutes. Transfer from Istanbul’s airports and accommodation in Sapanca are included in the treatment fee. When you leave, you receive copies of your X-rays, a treatment summary and your implant card; questions between the stays and after your return are answered on WhatsApp (see aftercare and follow-up).
How do we plan four or six implants at Rönesans?
At our clinic in Serdivan, fixed bridges for the whole jaw are fitted on four or six implants. Which concept suits you, or whether a different number makes sense, is decided at the examination; the bone is assessed with the clinic’s CBCT scanner. We carry out bone grafting and sinus lifts at the clinic, and treatment under general anaesthetic is possible when needed. The bridge is made with CAD/CAM by the dental laboratory we work with.
You know from the start which dentist will treat you, and before treatment begins you receive a written treatment and cost plan; the make and model of the implants are in it, and the batch details are on your implant card. How many implants other situations need is explained in our guide How many implants do you need?.