Implant Preparation Procedures
Over time, the jawbone associated with missing teeth can atrophy or be reabsorbed. This often leaves a condition in which there is poor quality and quantity of bone suitable for placement of dental implants.
Today, we have the ability to grow bone where needed. This allows us to place implants of proper length and width, restoring functionality and aesthetic appearance.
Minor and Major Bone Grafting
Potential implant sites with inadequate bone structure due to previous extractions, gum disease or injuries can be repaired through bone grafting. The bone can either be obtained from a tissue bank or the patient’s own bone.
Major bone grafts are typically performed to repair defects of the jaws arising from traumatic injuries, tumor surgery or congenital defects. Large defects are repaired using the patient’s own bone. The bone harvested depends on the size of the defect. The skull (cranium), hip (iliac crest), 3rd molar areas (cortical) and lateral knee (tibia), are common donor sites. These procedures are routinely performed in an operating room and require a hospital stay.
Sinus Lift Procedure
Today the sinus graft makes dental implants possible for many patients whose options may have once been limited to wearing loose dentures.
Sinuses are like empty rooms. Some of the roots of the natural upper teeth extend up into the maxillary sinuses, which are behind the cheeks and on top of the upper teeth. When the upper teeth are removed, there is often just a thin wall of bone separating the maxillary sinus and the mouth. Because dental implants need substantial bone to hold them in place, it is impossible to place them in a very thin sinus wall.
The solution is a sinus graft or sinus lift graft, in which the dental implant surgeon enters the sinus from where the upper teeth used to be. The sinus membrane is then lifted upward and donor bone is inserted into the floor of the sinus (which is the roof of the upper jaw.) After several months of healing, the bone becomes part of the patient’s jaw and dental implants can be inserted and stabilized in this new sinus bone.
If enough bone between the upper jaw ridge and the bottom of the sinus is available to stabilize the implant well, sinus augmentations and implant placement can sometimes be performed as a single procedure. If not enough bone is available, the sinus augmentation is performed first and the graft is left to mature for several months, depending upon the type of graft material used. Once the graft has matured, the implants can be placed.
Sinus bone grafts may also be performed to replace bone in the posterior upper jaw. Special membranes may be utilized that dissolve under the gum, protecting the bone graft and encouraging bone regeneration. This is called guided bone regeneration or guided tissue regeneration.
In severe cases, the bone ridge has been reabsorbed and a bone graft is needed to increase ridge height and/or width. This technique, in which the bony ridge of the jaw is literally expanded by mechanical means, restores the lost bone dimension when the jaw ridge gets too thin to place conventional implants. Bone graft material can be placed and matured for a few months before placing the implant.
In some cases, 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 the second premolar. Since there is almost always some postoperative numbness of the lower lip and jaw area (which dissipates very slowly, if ever), this procedure is considered a very aggressive approach. Other less aggressive options are usually considered first.
Typically, the surgeon removes 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, pulling it slightly out to the side and simultaneously placing the implants. The bundle is then released and placed back over the implants. The surgical access is refilled with bone graft material and the area is closed.
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, from the area of the chin or third molars, or from 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 tibia at the knee. Using the patient’s own bone for repairs generally produces the best results.
In many cases, however, we can use allograft material to implement bone grafting for dental implants. This bone is prepared from cadavers and used to promote the patient’s 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.
These surgeries are performed in our surgical suite under IV sedation or general anesthesia. After discharge, bed rest is recommended for one day and limited physical activity for one week.