An increase in bone volume through a bone graft allows for greater stability and durability of the implant
Pre-implant bone grafts are indicated when dental implants cannot be placed due to a lack of sufficient bone volume. There are several types of pre-implant bone grafting techniques
OUR SOLUTIONS FOR INCREASED BONE VOLUME
IT IS THE PREREQUISITE FOR THE DURABILITY OF IMPLANTS
PRE-IMPLANT BONE GRAFTS
WHAT IS A PRE-IMPLANT BONE GRAFT?
Pre-implant bone grafts are procedures that aim to increase bone volume when it is insufficient to place one or more dental implants in optimal conditions. An increase in alveolar bone volume through a bone graft allows for greater stability and durability of the implant.
Why is the alveolar bone volume insufficient?
Following the loss or extraction of a tooth, physiological and/or pathological bone resorption occurs systematically. The volume of alveolar bone (i.e. the part of the jawbone that surrounds, supports and holds the teeth) is said to be insufficient when it no longer allows for the placement of one or more dental implants in good conditions of length, diameter and number.
This is why it is advisable to place a dental implant immediately after the extraction of a tooth when possible: the native alveolar bone will not have time to resorb.
Explanation: When the masticatory physiology of the teeth is normal, the alveolar bone maintains its volume thanks to spontaneous mechanisms of bone regeneration.
When a tooth is lost or extracted, the alveolar bone that surrounds the roots of the teeth gradually decreases in volume (width, thickness and height) by 40 to 60% over the next three years. It is therefore advantageous to perform a dental implant placement as soon as possible after tooth loss.
If a tooth was extracted a long time ago, then the bone volume is often already too resorbed to place an implant under optimal conditions. As the number of teeth increases, this resorption phenomenon becomes more pronounced.
If a tooth has fallen out spontaneously, it is obviously because the bone structure that holds it in place has partially or totally disappeared. By definition, the bone volume will be reduced and eventually insufficient to place dental implants.
For all these cases, the solution is to proceed with a pre-implant bone graft in order to restore the optimal bone volume to place a dental implant in good physiological conditions.
BONE GRAFTING:
A NECESSARY STEP FOR THE INSTALLATION OF DENTAL IMPLANTS?
When are pre-implant bone grafts indicated?
Pre-implant bone grafts are performed on patients with insufficient alveolar bone volume to perform a dental implant placement in good mechanical and physiological conditions.
The decision to graft bone is made following the diagnosis of insufficient implant bone volume. This diagnosis is made according to the results of the exploration of the available alveolar bone volume performed with a 3D scanner. This examination, performed with a 3D cone beam scanner, is essential to accurately measure the amount of bone in the area that will receive the dental implant. In addition, it is easy to check for the presence of a surgical obstacle at the same time.
Surgical procedures for bone augmentation are mandatory in complex implantology cases, such as implant placement after multiple extractions and immediate loading.
WHY PERFORM A BONE GRAFT BEFORE PLACING A DENTAL IMPLANT?
It is not always possible to place a dental implant directly. The rules of implantology imply that intraosseous dental implants are placed in a sufficient volume of alveolar bone to allow good healing and vascularization of the bone in order to reduce the risk of peri-implantitis. This implies that the alveolar ridge of the maxilla in which the implants are placed must have a sufficient volume of available implantable bone. Similarly, the quality of the bone is essential: bone that is not very dense, fatty or poorly vascularized will be contraindicated for the placement of dental implants. The alveolar bone that receives the dental implant must provide an effective anchorage for the implants to ensure the durability of the implant-supported dental prosthesis.
However, the alveolar bone can have an insufficient height or width:
- Or because the bone capital in some patients is naturally insufficient with a thin morphotype.
- Either because the bone has resorbed, physiologically or pathologically, following tooth extractions (see the chapter on bone grafts).
In addition, anatomical structures can be obstacles to the placement of dental implants such as:
- The inferior alveolar nerve pair (NAI) that runs along the posterior and horizontal part of the mandible on the right and left.
- The maxillary sinus pair above the posterior basal part of the maxilla and in the cheekbone or (zygomatic bone) on the right and left.
- The nasal cavities above the anterior part of the maxilla at the level of the incisivo-canine block.
Therefore, if the quantity and quality of the bone of the implantable bone crests has become insufficient, it is necessary to increase its volume and density through bone grafts and the addition of growth factors contained in Plasma Rich Platelet (PRP) and Plasma Rich Fibrin (PRF).
This is the field of pre-implant surgery. The different surgical techniques available to increase the available bone volume will be discussed in this chapter.
Bone grafts used in pre-implant surgery are either :
- A bone graft with a bone harvest from the edentulous patient. It is a bone autograft since he is both donor and recipient.
- A bone graft without bone harvesting with a biomaterial as bone graft. The edentulous patient is a recipient but not a donor. It can be an allogenic or xenogenic or synthetic graft.
YOU ARE UNIQUE!
CLINICAL CASES OF BONE RESORPTION
CLINICAL RESULTS OF PRE-IMPLANT BONE GRAFTS
WHICH TYPES OF PRE-IMPLANT BONE GRAFTS
AND FOR WHICH VOLUME RESTORATION?
There are several types of pre-implant bone grafting protocols. The choice of technique depends on the predominant direction of the volume shortage. We distinguish
- Vertical augmentation when there is not enough alveolar bone height for the implant,
- Horizontal augmentation when there is not enough alveolar implant bone thickness
- Filling of the dental alveolus after one or more simultaneous dental extractions to restructure the implant alveolar bone volume in all directions.
Depending on the type of graft performed, the surgical technique of pre-implant bone grafts can be performed either in the dental office or in the clinic, respectively under local or general anesthesia.
Most minor non-invasive surgical procedures are performed in the dental office under semi-unconscious intravenous sedation with the assistance of an anesthesiologist.
In the upper jaw:
Following vertical resorption of the posterior alveolar bone of the upper jaw, the bone graft to compensate for the lack of alveolar bone height is the sinus filling technique or sinus lift (sinus floor elevation).
This protocol is indicated in cases of high bone insufficiency in the posterior areas of the maxilla below the sinus.
The air cavity formed by the sinus increases in volume, by a phenomenon of pneumatization, when one or more molars are extracted and sometimes the premolars. The sinus is gaining space at the expense of the alveolar bone available to place implants, following the loss of these teeth. The lower part of the sinus cavity volume must be filled with a bone graft to restore the implant alveolar bone volume.
This protocol is chosen when the residual height below the sinus does not exceed 8 millimeters.
In some cases of large vertical resorption, the sinus lift technique can be associated with the technique of apposition grafting with a screw matrix or ROG (guided bone regeneration).
In the lower jaw:
Following vertical resorption of the posterior alveolar bone of the lower jaw, the bone grafting technique used to compensate for the lack of height of the implant-bearing alveolar bone is the apposition grafting technique with a screw-retained matrix or ROG (guided bone regeneration). A titanium wire mesh is attached to the bone with screws and relieves the graft from the pressure of the overlying soft tissue to limit the resorption of the graft, induced by this pressure during healing.
This protocol is indicated in cases of high bone insufficiency in the posterior areas of the lower jaw.
This protocol is chosen when the residual height above the inferior alveolar nerve does not exceed 8 millimeters.
Following horizontal resorption of the posterior or anterior alveolar bone of the lower or upper jaws, the bone grafting technique for compensating for the lack of thickness of implant-borne alveolar bone is the apposition grafting technique with a screw-retained matrix or ROG (guided bone regeneration). A titanium wire mesh is fixed with osteosynthesis screws around the edge of the alveolar bone gap. This grid guides the osteosynthesis and relieves the bone graft of soft tissue pressure. This pressure is known to counteract neo angiogenesis. Thus, limiting the pressure on the graft is equivalent to encouraging the creation of a new vascular network and consequently limiting the resorption of the graft induced by this pressure during healing.
This type of graft is performed on the external vertical walls of the upper and lower jaws when the bone is not thick enough.
However, horizontal grafting techniques are varied:
- Guided Bone Regeneration (GBR),
- Segmental osteotomies,
- Appositional bone autograft with fixation and osteosynthesis
- Longitudinal expansion osteotomies.
Following horizontal resorption of the posterior or anterior alveolar bone of the lower or upper jaws, the bone grafting technique for compensating for the lack of thickness of implant-borne alveolar bone is the apposition grafting technique with a screw-retained matrix or ROG (guided bone regeneration). A titanium wire mesh is fixed with osteosynthesis screws around the edge of the alveolar bone gap. This grid guides the osteosynthesis and relieves the bone graft of soft tissue pressure. This pressure is known to counteract neo angiogenesis. Thus, limiting the pressure on the graft is equivalent to encouraging the creation of a new vascular network and consequently limiting the resorption of the graft induced by this pressure during healing.
This type of graft is performed on the external vertical walls of the upper and lower jaws when the bone is not thick enough.
However, horizontal grafting techniques are varied:
- Guided Bone Regeneration (GBR),
- Segmental osteotomies,
- Appositional bone autograft with fixation and osteosynthesis
- Longitudinal expansion osteotomies.
THE TWO MAIN TECHNIQUES OF BONE GRAFTING
Pre-implant bone grafts with bone harvesting from the patient
It is a so-called autologous or autograft: the surgeon comes and takes the graft from the patient
- Extraoral: on the cranial parietal bone, on the iliac bone, on the humeral bone,
- Intra-oral: on the chin bone or ramic bone at the lower base of the lower jaw.
In this type of autograft, the surgical technique will necessarily include two operative steps and two operative sites for bone harvesting and graft fixation.
Pre-implant bone grafts without bone harvesting from the patient
There are other types of grafts manufactured and distributed by pharmaceutical companies:
- Allografts: grafts from voluntary living human donors;
- xenografts: grafts of animal origin ;
- alloplastics or synthetic biomaterials
In this type of graft, which involves pharmaceutical products, the surgical technique will include an operating time and an operating site for fixation of the graft without bone removal.
The only site external to the graft site is possibly the site where blood is drawn to do PRFs.
HOW IS THE PRE-IMPLANT BONE GRAFTING PROCEDURE PERFORMED?
The graft is performed under local anesthesia, with or without the aid of intravenous sedation. It is also possible to perform it under general anesthesia.
The dental surgeon places the graft, then immobilizes it with different techniques depending on the type of graft. This bone graft is sometimes supplemented by a contribution of FRP (Fibrin Rich Plasma).
Dental implants can be placed :
- Either immediately at the time of the bone graft
- That is, four to six months after the operation. In this case, before the implantation, the dental surgeon performs a CT scan to check if the bone volume is optimal.
The usual postoperative course of a preimplant bone graft depends on various intrinsic and extrinsic factors: complexity, extent, operating time, location of the operation, presence of a venous line, type of graft,
Transplantation is an operation and there is no such thing as minor surgery. The healing period is a delicate phase where various hazards can occur: loosening or breaking of the sutures, infection, uncontrolled inflammation, etc.
During this time, pain or swelling may occur.
Complications occur at a very low rate of less than 10% but are statistically unavoidable.
It is important to follow certain recommendations and contraindications during the healing process:
- Smoking is absolutely forbidden one month before the operation, and definitely forbidden afterwards.
- It is advisable to sleep on the back, without pressure on the cheek on the side where the graft was performed to avoid tearing the sutures. For this purpose, the wearing of an inflatable collar (airplane type) is recommended so as not to sleep on the operated side and pull on the sutures.
- Extreme sports are prohibited, as well as activities that require head down positions (yoga, martial arts, etc.)
- In the case of sinus bone grafting, you should blow your nose gently for the first three weeks.
- Excellent oral hygiene is essential. Mouthwash is not allowed. The gums should be cleaned with a surgical brush after each feeding.
- During the days following the operation, the food ingested should be soft, cold or warm. Hot, salty and acidic foods should be avoided.
Any surgical operation has a risk of complications. If in doubt, do not hesitate to contact the surgical team.
The most important risk is an infection of the graft that can come from the sinus, or from late gingival healing. The infection must be eliminated by antibiotic treatment or even by bone curettage. The infectious focus may lead to the loss of a piece of the graft, which may require a new operation.
Fortunately, the risk of infection is not widespread. It occurs in only 5 to 10% of operations, and is mostly observed in patients who smoke, are diabetic, or who do not follow rigorous oral hygiene after the operation.
