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All-on-4 Dental Implants: Uses, Surgery & Risks [with Pictures]

All-on-4 dental implants treatment is a surgical procedure that involves the rehabilitation of a completely edentulous jaw with only four implants, and attaching a full-arch fixed prosthesis to these implants on the day of surgery. Edentulism is the condition of being toothless (complete or partial), which has a major impact on general and psychological health. Teeth make us look good when we smile or talk. They help us cut, grind, and chew the food. Also, teeth play a major role in the pronunciation of various sounds (s, z, j, x, d, n, l, t, f, v, & th). Edentulism lowers the patients’ quality of life, and makes them embarrassed when they smile, talk, or eat, leading to decreased self-esteem.

Dental implants provide a solution for patients with a completely edentulous jaw. The dentist places eight implants in the upper jaw and six implants in the lower jaw to support a full-arch fixed prosthesis. However, this solution is expensive and not suitable for patients with moderate to severe bone loss. So, a new solution is needed. At the end of the 1990s, Portuguese dentist Paulo Maló and the implant manufacturer Nobel Biocare developed the All-on-4 dental implants concept, which is a fast, cost-effective alternative to conventional implant techniques. In this article, we will discuss:

  • What is a dental implant?
  • Conventional implant technique vs. All-on-4.
  • All-on-4 step by step.
  • What to expect after the procedure?
  • Post-operative instructions.

What is a Dental Implant?

To fully understand the All-on-4 dental implants concept, you should first know what a dental implant is. The implant is an artificial tooth root that is surgically placed into the jawbone below the gum line to replace a missing tooth/teeth. The jawbone fuses with the implant (osseointegration), providing stable support for a dental prosthesis such as a crown, bridge, or denture. A conventional dental implant consists of:

  • The implant-body: it looks like a screw and is made of titanium or zirconia. The implant-body function is to provide support for a dental prosthesis. The dentist places the implant-body into the jawbone. After that, the bone grows and fuses with implant-body (osseointegration), which can take from 4 to 6 months.
  • The abutment: it connects the implant-body to the dental prosthesis. The abutment can be straight or angulated.
  • The dental prosthesis: the implant-supported prosthesis can be categorized into:
    • A fixed prosthesis such as crown and bridge.
    • A removable prosthesis such as a denture.
Structure of a Dental Implant
To fully understand the All-On-4 dental implants concept, you should first know what a dental implant is.

What is the All-On-4 Dental Implants?

The All-on-4 dental implants treatment is a surgical, prosthodontic procedure that involves the rehabilitation of an edentulous jaw by placing four implants only. These four implants support a full-arch prosthesis, which contains 10 to 14 artificial teeth. The All-on-4 is suitable for patients who have an edentulous jaw with or without remnant hopeless teeth. Also, All-on-4 dental implants treatment is best for patients who have jawbone loss that prevents them from getting dental implants by using conventional techniques.

Conventional Dental Implant Technique

Conventionally, to support a full-arch fixed prosthesis in an edentulous jaw, you will need at least eight implants in the upper jaw and six implants in the lower jaw. Also, you may need a bone graft if the jawbone is thin, soft, or insufficient to create a more solid base for the implants. After the placement of the implants, you won’t receive any prosthesis until the osseointegration is complete (delayed loading of the implants). Because attaching the prosthesis to the implants during the healing period (osseointegration) can cause implant movement and failure. Sometimes, the dental implant is contraindicated because the jawbone is insufficient or/and the anatomical structures such as maxillary sinuses or nerves are too close. Note: osseointegration is the fusion between the jawbone and the implant, which can take from three to six months.

All-On-4 Dental Implants Concept

While in the All-on-4 dental implants, you will need four implants only to support a full-arch fixed prosthesis. Your dentist will insert two implants in the anterior region (the place of lateral incisors) and two implants in the posterior molar region at a maximum angle of 45°. The All-on-4 dental implants treatment takes advantage of the dense bone in the anterior region. Besides, placing the posterior implants at an angle makes the implant secure and stable, which usually eliminates the need for a bone graft (graft-less procedure). Often, you will receive a provisional fixed prosthesis on the day of the surgery (immediate loading of the implants), which you will wear during the healing period (osseointegration). The All-on-4 is usually best for patients with close anatomical structures such as maxillary sinuses and nerves because tilting the posterior implants helps avoid the anatomical structures.

All-On-4 Dental Implants
In the All-on-4 dental implants, you will need four implants only to support a dental prosthesis.

Advantages of All-On-4

  • Fewer implants, less cost (cost-effective solution).
  • Suitable for patients with a thin or narrow jawbone. No need for a bone graft (graft-less procedure).
  • Suitable for patients with close anatomical structures such as maxillary sinuses and nerves.
  • You can receive a provisional fixed prosthesis on the day of the surgery (immediate loading of the implants).
  • It supports a fixed prosthesis, which is:
    • Better in aesthetics and chewing function than a removable prosthesis.
    • More comfortable than a removable prosthesis.

Disadvantages of All-On-4

  • Higher load on the inclined implants.
  • Possible problems due to the immediate loading of the implants.
  • The provisional prosthesis will increase the total cost of the procedure.

Is the All-On-4 Dental Implants Suitable for All Patients?

Generally, All-on-4 dental implants treatment is suitable for patients with a completely edentulous jaw, especially if they:

  • Have a thin or narrow jawbone.
  • Have close anatomical structures such as maxillary sinuses and nerves.
  • Looking for a cost-effective alternative to conventional implant techniques.
  • Want a provisional prosthesis on the day of the surgery (immediate function).
  • Want a permanent fixed prosthesis.

You can talk to your dentist to see if the All-on-4 dental implants treatment is the right option for you.

Contraindications

Usually, dental implants are suitable for patients with a missing tooth/teeth. However, they are contraindicated in the following cases:

  • During pregnancy.
  • Patients younger than 18 years old.
  • Heavy smokers.
  • Alcoholism and drug abuse.
  • Patients receiving radiotherapy or chemotherapy.
  • Medical conditions that affect the healing process:
    • Uncontrolled diabetes mellitus.
    • Bleeding disorders.
    • Immune suppressive disorders.
    • Bone disorders such as Paget’s disease.

You need to visit your dentist to see if the dental implants are suitable for you because every patient needs to be evaluated on an individual basis.

All-On-4 Dental Implants Procedure (Step-by-Step)

Pre-Operative Planning

The pre-operative planning is necessary for the success of the All-on-4 dental implants procedure. So, your dentist will:

  • Review your medical history: some medical conditions such as diabetes mellitus and bone disorders can affect the healing process, causing implant-failure. So, tell your dentist about previous and existing medical conditions and any medications you take to prevent complications.
  • Examine your mouth: your dentist will examine your mouth with a mirror and probe and take a dental impression to make a study model. Also, your dentist will ask for a 3D x-ray (cone beam computed tomography CBCT). The CBCT provides accurate information about:
    • The quality and quantity of bone.
    • The location of anatomical structures such as maxillary sinuses and nerves.
  • Make a treatment plan: the dentist will use your study model and CBCT to make a treatment plan, which includes:
    • The extraction of remaining and damaged teeth.
    • Planning the exact position and angulation of the implants.
    • Making a surgical guide for precise implant insertion.
    • The prefabrication of a provisional prosthesis for attaching it immediately after the surgery (immediate function).
    • Determining the type of final prosthesis.

Anesthesia

The all-on-4 dental implants procedure is oral-surgery. So, you will need anesthesia to feel comfortable during the procedure. The anesthesia options include:

  • Local anesthesia: often, the dentist uses local anesthesia for the placement of the implants. Local anesthesia won’t interfere with your state of alertness, and you will be awake during the procedure.
  • Conscious sedation: your dentist may offer local anesthesia in combination with conscious sedation to help you reduce anxiety and discomfort during the procedure. It will produce a dream like-state and make you feel relaxed. Conscious sedation is beneficial for patients with extreme dental anxiety. You may receive the medication used in conscious sedation through:
    • Oral tablets.
    • Intramuscular injection (IM).
    • An intravenous line (IV).
    • Inhalation (nitrous oxide).
  • General Anesthesia: under general anesthesia, you will be completely unconscious and won’t remember or feel anything that is occurring during the procedure.

Visit your dentist to discuss which anesthesia option is suitable for you.

The Placement Surgery

The dentist or oral surgeon performs the All-on-4 dental implants treatment in two ways:

  • Conventional surgery (with flap).
  • Flapless surgery (flapless approach).

Conventional Surgery (with Flap)

First, your dentist will use a scalpel to make an incision in the gum (flap) and expose the jawbone underneath. Then, your dentist will place the four implants in the jawbone using the All-on-4 guide. The dentist will place two implants in the posterior region at a maximum angle of 45°, and two implants in the anterior region (in the place of lateral incisors). After that, your dentist will suture back the flap and connect the abutments to the implants. After suturing, the dentist will attach a provisional fixed prosthesis to the implants (immediate loading of the implants). You will receive the final prosthesis after a sufficient healing period. Sometimes, your dentist may recommend a conventional healing period before receiving a provisional or final prosthesis (delayed loading of the implants).

Conventional All-On 4-Surgery (with Flap)
In conventional All-on-4 surgery, the dentist makes an incision in the gum (flap) to expose the jawbone underneath. Then, the dentist places four implants in the jawbone using the All-on-4 guide.

Guided Surgery (Flapless Approach)

The dentist or surgeon will use your cone-beam computed tomography (CBCT) and special software to plan the exact position and angulation of the implants virtually. Then, the surgeon will send this planned CBCT to the dental laboratory for the fabrication of a custom-designed surgical guide. This surgical guide ensures precise and efficient implant placement without the need for a flap (flapless approach). After the placement of the implants with the surgical guide, the dentist will attach the abutments and provisional prosthesis to the implants on the day of the surgery (immediate loading of the implants). Sometimes, your dentist may recommend a conventional healing time before attaching a provisional or final prosthesis to the implants (delayed loading).

The guided implant placement surgery is a minimally invasive technique, which minimizes the risk of pain and swelling, and ensures accurate, safe, predictable implants placement. However, it will increase the total cost of the procedure.

Guided All-On-4 Dental Implants Surgery
Guided All-on-4 dental implants surgery (Flapless Approach) minimizes the risk of pain and swelling, and ensures accurate, safe, predictable implants placement.

Healing Time

After the placement of the implants in the jawbone, the bone begins to grow and fuses with the implants (osseointegration). This process can take from three to six months, depending on the quality of the bone. Usually, you will receive a provisional fixed prosthesis on the day of the surgery (immediate loading) to wear during the healing period. After the osseointegration is complete, you will receive the final prosthesis. Sometimes, the dentist or surgeon recommends delayed loading protocol, which means that you won’t receive a provisional or final prosthesis until osseointegration is complete.

The Dental Prosthesis

The Provisional Prosthesis

On the day of the surgery, you may receive a provisional all-acrylic bridge, to wear during the healing period. Sometimes, the dentist converts an existing denture into a provisional bridge. The all-acrylic bridge is not suitable as a long-term prosthesis because of its weak resistance and durability.

The Final prosthesis

The All-on-4 final prosthesis is highly esthetic and available in different material options:

  • Acrylic teeth and gingiva over a titanium framework.
  • Composite veneered over a titanium framework.
  • Porcelain crowns cemented on a metal framework.

Both acrylic and composite look similar to natural teeth and are economic options. Porcelain is a more expensive, popular, and superior option. Porcelain looks identical like natural teeth and is more durable than acrylic and composite.

What to Expect After the All-On-4 Dental Implants Surgery?

Like any surgical procedure, you may experience discomfort after the All-on-4 dental implants surgery. So, your dentist will prescribe painkillers to help you control the pain after surgery. Also, you may experience:

  • Swelling of your gums and/or face.
  • Bruising of your gums and/or face.
  • Minor bleeding and pain at the site of the surgery.
  • Limited mouth opening.

These signs and symptoms are normal after the surgery, and you can control them by using painkillers and anti-inflammatory medications. However, if these signs and symptoms get worse, you should visit your dentist or surgeon immediately.

Instructions After the All-On-4 Dental Implants Procedure

Before the surgery, ask your dentist or surgeon about the steps of the procedure, the type of anesthesia suitable for you, and postoperative instructions. These instructions are similar to postoperative instructions after tooth extraction.

On the Day of the Surgery (in the First 24 Hours)

  • Take the prescribed painkillers and anti-inflammatory medications to control the pain.
  • Maintain good oral hygiene by using a soft-bristled toothbrush.
  • Avoid things that may disturb the blood clot and promote bleeding:
    • Avoid hot foods and drinks.
    • Don’t spit or rinse your mouth.
    • Avoid aspirin because it inhibits blood clotting.
    • Don’t touch the surgical site with your finger or tongue.
    • Avoid lifting heavy objects and exercise.
  • Apply cold compresses (ice-packs) to your face. This will help reduce the swelling. Note: put a towel between the ice-pack and your face to avoid ice burn.
  • Avoid smoking because it affects the healing process and increases the risk of implant failure.
  • Proper nutrition is important for the healing process. So, you should:
    • Eat soft, cool foods such as mashed potatoes, eggs, and a milkshake.
    • Avoid foods such as chips, popcorn, and nuts.
    • Avoid alcohol drinking.
  • Ask a family member or a friend to take you home after the surgery because you may not be able to drive.

Instructions After the First 24 Hours

  • Rinse your mouth with warm salt water (half a teaspoon of salt to a cup of warm water).
  • Or you can use a chlorhexidine mouthwash twice daily.
  • Limit physical activities in the first 48 hours after the surgery, and avoid exercise and lifting heavy objects to prevent postoperative bleeding.
  • Don’t smoke because smoking affects the healing process and can cause implant failure.
  • Contact your dentist if you have questions or problems.

Following these instructions will help you speed the healing process and prevent complications.

Complications of the All-On-4 Dental Implants Procedure

The All-on-4 dental implants treatment has over 95% success rate. However, complications may occur like any surgical procedure.

Complications During the Surgery

There are always risks involved with any surgical procedure. The risks include:

  • Infection at the surgical site.
  • Injury to the nerve, which can lead to numbness or tingling of the lip, tongue, and chin.
  • Injury to blood vessels, which can lead to excessive bleeding.
  • Perforation of the maxillary sinus, which can lead to a sinus infection.
  • Poor primary implant stability, which can lead to implant failure.

Complications During the Healing Period (in the First 6 Months)

Sometimes, the implant fails to integrate with the jawbone (failure of osseointegration), leading to implant mobility and failure. The failure of osseointegration may occur due to several factors such as poor oral hygiene, smoking, uncontrolled diabetes, and poor primary stability during the surgery.

Long-Term Complications

In some cases, a destructive inflammatory process may affect the bone surrounding the implants, causing bone loss. This condition is known as peri-implantitis, which may occur due to poor oral hygiene, smoking, bruxism, gum disease, and uncontrolled diabetes.

Conclusion

Do you have an edentulous jaw? Are you looking for a cost-effective alternative to the conventional implant technique? All-on-4 dental implants could be a suitable option for you. Conventionally, the dentist places eight implants in the upper jaw and six implants in the lower jaw to support a full-arch bridge. While in the All-on-4, the dentist places four implants only per jaw to support a full-arch bridge. Fewer implants mean less cost. Besides, the All-on-4 is suitable for edentulous patients with minimum jawbone volume because the dentist places the posterior implants at an angle, which makes them secure and stable. Visit your dentist to know if the All-on-4 is suitable for you, how the procedure is performed, and what is the cost of the procedure.

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