Bone resorption, or deterioration, occurs naturally when teeth are lost or removed unless dental implants are placed to preserve the bone. This often results in a situation where there is insufficient bone, or poor quality bone that is not adequate for the placement of dental implants.
Fortunately for patients who have lost bone, it is possible to grow bone, or replace the bone with grafting techniques and successfully place dental implants that are the proper length and width for ideal function. In addition, any defects in the bone in the front of the mouth can be corrected to create the proper facial contours and tissue support necessary to achieve optimal esthetic results.
Small defects in the desired implant site can be grafted with either real or synthetic bone to fill in the defects. Since gum tissue grows faster than bone and can permeate the bone graft, causing it to shrink, a thin collagen membrane is used to cover the graft and encourage bone regeneration. The membrane dissolves under the gum tissue. Sometimes the bone graft can be accomplished at the same time as implant placement. This type of graft takes the same time to heal as it takes for the bone to remodel after the implants have been placed.
If there is a substantial amount of bone loss, a block of bone can be removed from the chin or behind the lower back teeth and transplanted to the desired site. These blocks of bone are held in place using small titanium screws. The bone will often be covered with a thin collagen membrane to encourage bone growth. These grafts require from four to six months to grow new bone. Dental implants can then be placed securely into the new bone. It will usually take another three to four months for the bone to remodel around, or fuse to the dental implants.
Sinus Lift (Graft) Procedure
One of the challenges with replacement of posterior teeth in the upper jaw is the possibility that the sinuses have dropped down into the space vacated by the roots of the missing teeth. The sinuses are located behind the cheeks and on top of the upper teeth, some of which actually extend into the sinuses. When these teeth are lost or removed, there is often just a very thin wall of bone between the sinuses and the mouth. Dental implants must be placed securely into bone to hold them in place.
When the sinus wall is very thin, a special bone grafting procedure is required in order to place dental implants. This involves a delicate procedure to gently lift the floor of the sinus to create more space to pack bone grafting material in order to create an ideal site for the placement of the dental implants. After a period of a few to several months, the new bone matures, becoming part of the jaw and dental implants can be placed in this new sinus bone.
If there is sufficient bone between the ridge of the jaw and the bottom of the sinus to stabilize the dental implant, the sinus augmentation procedure and implant placement can sometimes be performed at the same time. If there is not enough bone available, the sinus lift (graft) procedure must be performed first, then after the graft matures, dental implants can be placed.