All-on-3 implantation (Trefoil)

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Nobel Biocare was the first company to offer many methods to restore teeth. Among them: zygomatic implants, implants with immediate loading, All-on-4 protocol. One of the company’s latest developments is the All-on-3 or Trefoil method. The method was patented in 2015, but began to be widely used in 2017. Scientific studies with the results of grafting in the long term are impossible to conduct due to the novelty of the technique.

Differences of the Trefoil protocol from other methods

• The design is placed on three implants. 3 titanium posts are inserted into the lower jaw, strictly vertically, at the same level.
• The titanium arch (beam) is an innovative invention. 5 joints allow for a stress-free fit (passive fit), which compensates for vertical, horizontal and angular deviations of the implants.
• The arch is manufactured in advance, without taking into account the individual characteristics of the patient. The design of the bar base is such that it can be adapted to any jaw.
• Drilling protocols ensure that the posts are placed parallel without deviation. This ensures a perfect fit of the prosthesis
• إن permanent prosthetic structure is fitted immediately.

Trefoil implants

A special post has been developed for this method. Its diameter is larger than most implants – 5 mm. The height is offered in two variants – 13 mm and 11.5 mm. They have a cylindrical shape with a conical head. The neck of the pin is smooth.

The products have a special sputtering – TiUnite. It consists of titanium oxide, with the addition of phosphorus. The surface is sandblasted so that the roughness enhances the contact between the pin and the tissue. This spraying provides primary stabilization and accelerates osseointegration.

TiUnit sputtering is used on all Nobel Biocare products and is well researched. High long-term engraftment results have been confirmed^[1].

When Trefoil implantation is used

The main indication for the protocol is complete adentia (missing teeth). It is not the only method of restoring teeth in cases of complete adentia, it is chosen if:

• All-on-4 and All-on-6 protocols cannot be applied as a result of anatomical peculiarities;
• the immediate loading protocol with a permanent denture is preferable for various reasons;
• the patient needs to restore teeth in a short period of time;
• lack of funds for other methods.

For proper placement of this type of implants, the jaw must be of a certain height and width. Implantation is only possible for patients with a bone width of at least 7mm and a height of no more than 13mm.

موانع الاستعمال

As with all implants with immediate loading, the list of medical contraindications is short:

• Blood diseases affecting blood coagulation;
• mental illnesses;
• autoimmune diseases;
• uncompensated diabetes mellitus.

To temporary prohibitions can include any infections, exacerbation of chronic diseases, age under 18 years, inflammatory diseases of the oral cavity.

Trefoil has limitations on anatomy: insufficient width and height of the jaw, narrow, wedge-shaped jaw, unusual jaw structure.

Stages of the procedure

1. Preparatory. Obligatory inspection of the oral cavity, collect anamnesis. It is very important to inform the doctor about chronic diseases, allergies, infections.
2. Diagnostic. A panoramic image or CT scan will allow you to see a complete picture of the jaw structure and develop an individualized treatment plan.
3. Surgical. Unfortunately, unlike other immediate loading protocols, Trefoil cannot be placed minimally invasively. A flap technique is used, in which the implantologist exposes the bone by cutting a flap in the gum. During the surgery, the doctor aligns the gum margin so that it is the same height throughout. The patient does not feel pain during the procedure, but this method leads to more pain after surgery, frequent swelling and lengthens the rehabilitation period. The implantologist screws 3 pins into the bone, then screws the bar structure, makes an impression and immediately makes an artificial jaw.
4. Prosthetics. Performed the same day or a new appointment is scheduled. The acrylic base mimics gum, and the artificial teeth look better than natural teeth. The problem is that all 3 implants are placed in the front. The overhanging part of the denture (unsupported) limits the number of artificial teeth. If, for anatomical reasons, it is not possible to place 12 teeth, this protocol will have to be abandoned. In this case, the All-on-4 method is considered.
5. Rehabilitation. A few days after surgery, swelling, pain, sometimes even fever is possible. Normally, everything passes quickly. If after 2-3 days there is no improvement, you need to go to the clinic.

Recommendations for care include regular oral hygiene, use of a wide floss (superfloss), professional teeth cleaning.

Since the denture is acrylic, it is prone to abrasion and easy compression. The base will have to be adjusted regularly, and the artificial teeth will have to be replaced with new ones.

Pros and cons of the technology

There is no ideal protocol for restoring teeth. In each case, the implantologist chooses the most appropriate one based on a variety of factors. The All-on-3 method is good because:

• Takes little time. Permanent dentures can be placed in 1 day. It is a turnkey method.
• Slows bone resorption. Implantation is the only way to prevent significant bone loss. After surgery, tissue metabolism and blood supply are improved, the facial oval is preserved, and the smile is younger.
• The price of All-on-3 Trefoil is more affordable, because the entire procedure takes 1 visit to the doctor, and the prosthesis does not need to be replaced.
• Long service life of the system. Compared to removable dentures, Trefoil is more durable, even if the denture has to be replaced, the implants and the bar structure will last for decades.

But the method has disadvantages. Chief among them is the lack of scientific research on the long term. All studies are currently limited to a time period of 3 years. What the results will be in 10 years, it is not yet known.

In addition:

• is only used on the lower jaw;
• requires a certain bone size;
• the surgery smooths the alveolar ridge, flattening the bone;
• there is no support in the lateral regions. This reduces the stability of the structure;
• an acrylic denture is fitted, which can cause allergic reactions.

Alternatives

The choice of any implantation method is made after analyzing all factors. The doctor takes into account general health, the state of the oral cavity, bone resorption, anatomical features. If for some reason, the use of the Trefoil method is impossible, the implantologist will offer other options.

• All-on-4. The fixed prosthesis is fixed on 4 implants, 2 in front and 2 on the sides. This provides better balance to the structure.
• All-on-6. More implants – better retention. Different types of posts can be combined to provide more stability.
• Resmile. A relatively new method developed on the basis of ROOTT implants. Number of prostheses. This protocol does not limit the number of posts, allows combining different types of posts, restores a full dentition (14 teeth). In Moscow, this protocol is used in the ROOTT IDC.
• Removable prostheses. Modern materials make such products comfortable to wear, similar to the natural appearance. Their disadvantage is that they do not stop bone loss. However, restoration of chewing function and aesthetic appeal is on the face.

Tooth loss has a big psychological effect, but modern dental restoration techniques bring back a smile 99.99% of the time.

Sources :

^[1]Osseous healing characteristics of three different implant types – PubMed (nih.gov)