Bone Grafting Techniques
Bone grafting is the replacement of supporting bone around the teeth which has been lost. It is also known as bone augmentation or ridge augmentation.Today, bone grafting procedures have become almost an integral part of implant reconstruction. In many instances, a potential implant site in the upper or lower jaw does not offer enough bone volume or quantity to accommodate a Rootform Implant of proper size or in the proper place. This is usually a result of bone resorption that has taken place since one or more teeth (if not all) were lost. Bone Grafting procedures usually try to re-establish bone dimension, which was lost due to resorption. .
Although your surgeon often knows in advance when a graft will be necessary, at times this is only discovered when the implant site is opened during surgery and he is prepared to replace the necessary bone.
Sinus is the term given to anatomical cavities that exist within our body.There is one in the region of the cheek bone that is termed the Maxillary Sinus.
Our upper teeth especially the back ones often have their roots dipping into or in close proximity to the maxillary sinus. The natural response to tooth loss is a shrinkage in the amount of bone existing around the tooth that was, this means that if an upper tooth is lost there is a decrease in the height of bone beneath the sinus. In such a situation if the patient wants Implants it becomes impossible to insert the implant in such a diminished height of bone, thereby necessitating such a procedure that would restore the bone height. readmore...
In severe cases the ridge has been reabsorbed and a bone graft is placed to increase the ridge height and/or width. In these situations, the graft is taken from another area inside your mouth or body. This dental implant bone grafting technique is where a block of bone is cut out of one area and screwed into the area where the dental implants will be placed. Normally, the block bone graft is placed and allowed to integrate into the jaw bone for four to six months before the dental implant is placed.
This office procedure is usually performed using general anesthesia and takes about an hour. These procedures may be performed separately or together, depending upon the individual's condition. There are several areas of the body which are suitable for attaining bone grafts. In the maxillofacial region, bone grafts can be taken from inside the mouth, in the area of the chin or third molar region or in the upper jaw behind the last tooth. In more extensive situations, a greater quantity of bone can be attained from the hip or the outer aspect of the tibia at the knee. These surgeries are performed in the out-office surgical suite under IV sedation or general anesthesia. After discharge, bed rest is recommended for one day and limited physical activity for one week.
In severe cases, the ridge has been reabsorbed and a bone graft is placed to increase ridge height and/or width. This is a technique used to restore the lost bone dimension when the jaw ridge gets too thin to place conventional dental implants. In this procedure, the bony ridge of the jaw is literally expanded by mechanical means. Bone graft material can be placed and matured for a few months before placing the dental implant.
The inferior alveolar nerve, which gives feeling to the lower lip and chin, may need to be moved in order to make room for placement of dental implants to the lower jaw. This procedure is limited to the lower jaw and indicated when teeth are missing in the area of the two back molars and/or and 2nd premolar, with the above-mentioned secondary condition. Since this procedure is considered a very aggressive approach (there is almost always some postoperative numbness of the lower lip and jaw area, which dissipates only very slowly, if ever), usually other, less aggressive options are considered first (placement of blade implants, etc.)
Typically, we remove an outer section of the cheek side of the lower jawbone in order to expose the nerve and vessel canal. Then we isolate the nerve and vessel bundle in that area, and slightly pull it out to the side. At the same time, we will place the implants. Then the bundle is released and placed back over the implants. The surgical access is refilled with bone graft material of the surgeon’s choice and the area is closed.
These procedures may be performed separately or together, depending upon the individual's condition. As stated earlier, there are several areas of the body that are suitable for attaining bone grafts. In the maxillofacial region, bone grafts can be taken from inside the mouth, in the area of the chin or third molar region or in the upper jaw behind the last tooth. In more extensive situations, a greater quantity of bone can be attained from the hip or the outer aspect of the tibia at the knee. When we use the patient’s own bone for repairs, we generally get the best results.
In many cases, we can use allograft material to implement bone grafting for dental implants. This bone is prepared from cadavers and used to promote the patients own bone to grow into the repair site. It is quite effective and very safe. Synthetic materials can also be used to stimulate bone formation. We even use factors from your own blood to accelerate and promote bone formation in graft areas.
Soft tissue, such as gum tissue, grows very fast while bone grows very slow. When a surgical hole is created by a surgeon, soft tissue grows into the surgical hole very quickly and blocks out bone from growing into the hole. When bone is needed in an area to place dental implants, uncontrolled gum tissue growth is a problem. A membrane barrier can be used to cover the surgical hole and block out the gum tissue from growing into the area. This allows the more slowly growing bone to fill the surgical hole without any competition.
The membrane barrier guides the gum tissue away from the surgical defect. Gums and bone are both tissues and both are guided by the artful placement of a membrane barrier. Because the bone regenerates in the surgical hole, the technique is called guided tissue regeneration. Some surgeons call it guided bone regeneration because implant surgeons are very concerned about the supporting bone around their dental implants.
Guided tissue regeneration can be used to repair defects around previously placed dental implants or to create additional bone in deficient areas before placing dental implants. The surgical hole can be filled with several different types of materials before covering the area with a protective membrane barrier. .
Deformities in the upper or lower jaw can leave you with inadequate bone in which to place dental implants. This defect may have been caused by periodontal disease, wearing dentures, developmental defects, injury or trauma. Not only does this deformity cause problems in placing the implant, it can also cause an unattractive indentation in the jaw line near the missing teeth that may be difficult to clean and maintain.
To correct the problem, the gum is lifted away from the ridge to expose the bony defect. The defect is then filled with bone or bone substitute to build up the ridge. Your periodontist can tell you about your options for graft materials, which can help to regenerate lost bone and tissue.
Finally, the incision is closed and healing is allowed to take place. Depending on your individual needs, the bone usually will be allowed to develop for about four to 12 months before implants can be placed. In some cases, the implant can be placed at the same time the ridge is modified.
Ridge modification has been shown to greatly improve appearance and increase your chances for successful implants that can last for years to come. Ridge modification can enhance your restorative success both esthetically and functionally.
Types of Bone Grafting Materials
With respect to the Bone Graft material used, we have to differentiate between several choices. All materials can be categorized into five different categories:
- Autograft or autogenous bone graft
- Allograft or allogenic bone graft
- Xenograft or xenogenic bone graft
- Alloplast or alloplastic bone graft
- Growth Factors
Each of the bone graft materials is usually developed with a specific purpose or advantage in mind. Your surgeon will make a decision with respect to the bonegraft material, based on your individual needs and the latest research in that field.
Healing Period After Bone Grafting
The healing period required after a bone graft ranges between three and nine months, depending on the individual case. The implant can be placed once the graft is completely healed. In some cases, implant placement and bone grafting can be done at the same time.
BONE GRAFTING FAQ
What is Grafting?
Grafting is a procedure used to replace / restore missing bone or gum tissue
A gum (gingival) graft is used to replace missing and / or receded gum tissue.
Types of gum tissue:
There are two types of gum tissue in the mouth, one of which surrounds the necks of the teeth and is thick and protective in nature (keratinized gingiva). The other of which lines our cheeks and floor of the mouth whose purpose is to be elastic and mobile in nature (mucosa).
Why is a gum graft needed?
Soft tissue grafts are used to replace missing thick tissue (keratinized gingiva), which has worn away from the necks of the teeth for a variety of reasons. The purpose of gum grafting is to minimize and/or arrest the progression of recession.
Unfortunately associated with every type of recession, there is bone loss, because the bone resides just beneath the gums. Therefore, if the gums have receded, then the bone too has receded. The purpose of gum grafting is to arrest the progression of recession and thereby halt the bone loss as well, by restoring a thick zone of protective tissue around the neck of the tooth / teeth which exhibits an absence of this thick keratinized gum tissue.
In certain instances it is not only possible to restore the missing keratinized (thick / protective) gum tissue, but also to cover the exposed root surface of the tooth / teeth in question. Other issues must be addressed as well, such as the biting forces being placed on the teeth.
Unbalanced forces placed on the teeth in the presence of clenching or grinding can predispose an individual to recession. Being a candidate for this root coverage procedure, which is achieved by a connective tissue graft, is to be determined by the individual practitioner.
Cosmetic Gum Grafts:
Esthetic gum grafting can be used to "plump up" the gum tissue in an area that is deficient and would result an unaesthetic cosmetic make-over. Remember the teeth and gums should exhibit symmetry, yet sometimes one side is deficient, therefore, gum grafting may be essential to achieve symmetry prior to a cosmetic make-over.
What causes recession?
1. Aggressive brushing - potentially? Some people believe that aggressive brushing with a hard bristled brush may be a co-factor in recession or erosion of the neck of the tooth
2. Excessive biting forces - clenching and/or grinding? This can result in bending / flexing of teeth, which will often result in fracture of a small portion of tooth structure at the gum line (abfractions) and consequently bone and gum recession
3. Maloccluded and misaligned teeth? Teeth that positioned outside the normal arch form of the jaw are subject to having abnormal forces placed on them causing recession
When treating recession by gum grafting, the causative factor must also be addressed in order for the grafting procedure to be successful.
What are the different types of Gum Grafts?
1. Soft tissue graft: There are many types of soft tissue grafts. This type of graft involves taking a small piece of tissue from the surface skin on the roof of the mouth and transplanting it to areas in the mouth that are lacking. This type of graft restores and augments the missing thick keratinized gingiva, but does not result in covering of the exposed root.
2. Connective Tissue Graft: In this procedure tissue is taken from the undersurface of the palatal tissue (roof of the mouth) via tiny incisions, and is used to not only restore missing thick keratinized gum tissue, but also used to cover exposed roots of the teeth.
What are the types of bone graft?
1. autogenous - bone taken from one area of the patient and transplanted to another area requiring such grafting
2. allograft - either synthetic bone or bone from a bone bank (cadaver bone)
3. xenograft - bovine /cow bone
Which graft is used and when and why?
Autogenous bone is the "gold standard" and oftentimes has the most predictable results. This is described as the best type of graft because such bone is live bone with live active cellular elements that enhance bone growth, whereas other types of grafts are devoid of any active cellular material. Allografts and Xenografts both do not require a second surgical site as does the autogenous bone. Ample amounts can be easily obtained.
In conjunction with bone grafting, membranes are often used to help stabilize the bone graft as well as displace the gum tissue from invading the healing bone graft. Gum tissue grows at a much faster rate than bone, therefore, membranes are used to prevent gum tissue from growing in and displacing the bone graft before it matures.
How is the sinus lift procedure performed?
The sinus lift is a surgical procedure. The specific technique that the dentist utilizes can vary depending upon their training and experiences but traditionally the procedure has been performed as follows:
- The dentist will make an incision in the patient's gum tissue on the cheek side of their upper jaw in the area where the placement of the dental implant is planned (in the region originally occupied by the patient's bicuspid or molar teeth). This incision allows the dentist to flap back the patient's gum tissue and expose the jawbone that lies underneath.
- The exposed bone is cut in a fashion where a "trap door" of bone, hinged at the top, is created. This movable section of bone is then pushed gently inward and upward into the sinus cavity. This bone movement caries the sinus membrane attached to it with it, thus "lifting" the membrane (and hence the sinus floor) to a new, higher level. The empty space underneath the lifted sinus membrane is then packed with bone-graft material thus providing the new bone into which the tooth implant will be placed
- Once the bone-graft material has been positioned the gum tissue is stitched closed.
- In some instances it can be possible that the dentist will place the dental implant at the same time that the sinus lift is performed. In most cases, however, a dentist will allow a healing period of six to nine months before the dental implant is placed. The specific time frame allowed for healing is dependent upon the type of bone-graft material that has been utilized
What types of bone-graft materials are used with the sinus lift procedure?
Several different types of bone-graft materials can be utilized with the sinus lift procedure. In some instances the patient's own bone will be used, such as bone harvested from another location in the patient's mouth or else from other bones (including the hip (iliac crest) or shin bone (tibia)). In other instances prepared bone (frozen bone, freeze-dried bone, demineralized freeze-dried bone), either human or from another species (i.e. bovine), can be purchased from a tissue bank for use. Another alternative involves the use of synthetically derived graft material such as hydroxyapatite.
The procedure involves placement of a bone graft that may be obtained from the patients body or may be synthetic bone substitutes.The surgery lasts around 1-2 hours & may be carried out under Local / General anesthesia. Normal activity may be resumed from the third day onwards.
The entire procedure is carried out from inside the mouth & there is no visible scar on the face, nor does it alter the facial topography in any way.There are generally no attending post-operative complications if all the given instructions are followed.