All-on-4 Dental Implants

The All-On-4 (All-On-Four) Dental Implants are a new dental implants technique originally developed in order to help edentulous patients with severe bone loss at the posterior areas of the jaw to get the benefits of implant supported dentures. All-on-6 and All-on-8 are variations of the same technique, but using a larger number of dental implants.

All-on-4 implants are often used for patients with severe jaw bone loss, too large or too low sinus cavities, or too shallow alveolar nerve in the lower jaw.

The All-on-4 technique requires the placement of only 4 denture implants, all in the anterior part of the jaw, where the jaw bone has usually the best density. In order to achieve better support the 2 implants towards the back of the jaw are placed at a high angle so that they can take advantage of the better bone quality at the front of jaw. With the all-on-4 design, the terminal abutments are tilted at a 30 degree angle from mesial to distal, thus extending the length of the metal framework that can be supported.

• Diagnostic phase (x-rays / CT scan) to determine if All-on-4 implants are suitable
• Preparation of a surgical template prior to dental implant surgery
• Teeth extraction (if required) and dental implant post placement
• Placement of the prosthetic restoration on the dental implant posts

All-on-4 can provide the following advantages:

• All-on-4 provide a solution for patients with very poor bone condition
• they are an alternative lower cost solution instead of bone grafting (even if possible)
• fewer implants can be used, lowering the cost of the overall treatment
• it is an immediate load technique that can shorten treatment time
• their placement is completed in a single appointment

Before you decide to take advantage of the all-on-four dental implants you should first consider some of the risks involved:

• Higher failure risk - The technique has been designed exclusively for patients with poor jawbone condition. A higher possibility of implant failure is expected in this high risk patient group.
• Combined failure risk - If one of the 4 supporting implants fails, the entire restoration fails and has to be reconstructed.
• Jaw fracture risk - Implants are placed only in the front jaw, therefore the jawbone deterioration continues at the posterior areas of the jaw increasing the risk of what is called a 'facial collapse'. If it becomes too weak, the jaw may fracture due to the pressure applied to the front part when eating.

The use of the All-on-4 implants technique has the following limitations:

• totally edentulous maxilla (upper jaw) with a minimum bone width of 5 mm and a minimum bone height of 10 mm from canine to canine
• totally edentulous mandible (lower jaw) with a minimum bone width of 5 mm and minimum bone height of 8 mm

All-on-6 dental implants is just a variation of the all-on-four technique based on the same concept, with the only difference that 6 front implants are used instead of four. Many dental implant dentists prefer the 'all-on-6' option because it is safer (a restoration can be placed even if one of the implants fails).

Another variation is the All-on-8 using 8 dental implants. Unlike the 'All-on-4' technique which uses acrylic dentures, 'All-on-8' uses dental bridges with crowns, which gives a more natural look to the teeth.

All-On-4 and their variations can help many patients who have limited amount of jaw bone and/or a limited budget. Decreasing the need for bone grafting can save a lot in healing time and treatment cost, but the higher risk of possible failures should also be considered.