Thursday, October 6, 2005
Dear Dr. Mady: I lost my back upper teeth years ago and now I can finally afford dental implants. When I went to discuss it with my dentist, he said that I probably don’t have enough bone to support implants. He is now referring me to an oral surgeon to see if anything can be done. What options do I have if I don’t have enough bone? -June in Markham
Dear June: As you probably now realize, over time the jawbone in the areas of missing teeth is resorbed or shrinks naturally. This often results in a situation in which there is poor quality and amount of bone remaining to support dental implant placement. In this specific situation, you would not be a candidate for dental implants.
In this day and age, however, there is a procedure known as bone grafting that can make these previous extraction sites suitable for dental implants. If successful, this will not only allow your oral surgeon to place implants of suitable width and length, but will also allow your dentist to restore proper dental function and esthetics.
Bone shrinkage is not always caused by extractions. There are other factors and conditions that promote resorption. These may include gum disease, genetics, previous oral or maxillofacial surgery, or trauma. Bone grafting procedures can repair inadequate implant sites. They involve surgical placement of bone from another area or source into the site with the resorption and then allowing it to heal.
The bone used in grafts can be obtained by various means, but the most common method is to use the patient’s own bone. This bone usually is taken from the patient’s own hip, jaw or tibia just below the knee. The removal of bone for grafting is usually accomplished by an orthopedic surgeon and then they transfer it to an oral surgeon immediately in the operating room so it can be placed in a prepared site where it is needed. Some specially trained oral surgeons today complete the entire process on their own without the help of an orthopedic surgeon.
If your surgeon feels that your own bone will not be adequate or if you decide together that the post operative pain is not desired, then you have other options. Freeze-dried cadaver bone is accessible and some surgeons even use artificial bone. The most common graft that I have seen is a hip graft from the patient’s own hip. This may require a short hospital stay. The only negative side effect is a sore hip for a short period of time which usually causes temporary limping. However, this does not always occur and I have witnessed some patients who experienced absolutely no hip symptoms after this type of graft.
Also, special membranes may be utilized that dissolve under the gums and protect the bone graft and promote bone regeneration. This procedure is called guided bone regeneration or guided tissue regeneration.
Some patients have very low sinuses in their upper jaw area where molars are or used to be. Often after upper molar extractions, there is merely a thin layer of bone separating the maxillary sinuses from the oral cavity. In a case where a routine graft is not a good option or where the membrane in extremely low, a procedure called a sinus lift graft can be performed.
The technique involves an oral surgeon entering the sinus from where the upper teeth used to be. The sinus membrane is then raised or lifted upward and donor bone is then placed into the floor of the sinus. After months of healing, this bone becomes part of the patient’s upper jaw and should then be thick enough for implants to be inserted. If just enough bone is available between the upper jaw ridge and the floor of the sinus pre-operatively, to stabilize the implant, then the implant(s) can be placed at the time of the sinus lift graft and overall treatment can be shortened by several months.
These surgical procedures are great when there is no other option than to wear dentures or partial dentures. Cost may be a factor in your decision, but as the old saying goes, “you get what you pay for”!
Thursday October 2, 2003.
Dear Dr. Mady: I finally can afford to have a coupleof dental implants put in my mouth to replace teeth lost twelve years ago. My dentist said that he is referring me to an oral surgeon for a bone graft and implant surgery. Why would I need a bone graft and what is it all about? –Bill in Walkerville
Dear Bill: In the years following the extraction of teeth, bone in your jaws where the teeth previously existed tends to resorb or shrink naturally. If you later want to place dental implants at these sites, it is often impossible without a graft of bone from somewhere else to re-establish what is missing. Basically you may now be, after twelve years, left with a situation where the quality and quantity of bone in those areas does not warrant implant placement.
The graft can increase the amount of bone in the area(s) and improve the shape of the alveolar jaw bone to make it more suitable. Also the chances of success for the titanium dental implants will rise. If there is not an adequate amount of healthy bone to support the implant, it may fail.
Bone grafting not only gives us the opportunity to place implants of proper width and length, but also allows an opportunity to restore esthetics and function. It is a surgical procedure that can sometimes be done right in the dental office, but it is most often completed by oral surgeons in their office or in a hospital setting.
Bone loss can also be caused from trauma, periodontal disease, infections or cysts. There are numerous techniques available today and there are several choices with respect to the bone graft material that can be utilized. The materials can basically be categorized into five different types.
The Autograft (autogenous) is the most common and most successful. This involves transplanting bone from one site of your body to your jaw. The site the bone is taken from is usually called the donor site. On the other hand, the site that receives the graft is known as the recipient site. Usual donor sites are your chin or back areas of your jaw itself. If these are not sufficient, then larger amounts can be taken from the iliac crest of one of your hips or from your shin bone (tibia).
The Allograft (allogenic) is a graft between you and another individual. The source for this is usually cadaver bone. There are issues involved with this including thorough screening to prevent cross infection if diseases exist, but larger amounts of bone can easily be sought after.
The Xenograft is a tissue graft between two different species. An example would be getting bone from a monkey.
The Alloplast involves the use of synthetic bone, not from humans or animals.
Lastly there are Growth Factors which are natural proteins found in our bodies that can be used to stimulate bone growth. These are known as BMP’S or bone morphogenic proteins. Their use is a potential future substitute for autogenous grafting, but they currently are not often utilized outside of clinical studies.
Your surgeon will select a bone grafting material base on your specific situation and will discuss all options with you.
Different types of grafting procedures themselves exist, but I see the most common as Ridge-augmentation, the Sinus Lift, and Nerve Repositioning.
Ridge Augmentation involves using the graft to increase the height and width of the bone ridge of the area in question. The Sinus Lift is performed by elevating the sinus membrane and placing bone onto the sinus floor. Nerve Repositioning involves moving of nerves to make room for guidance and placement of an implant, lessening the possibility of paresthesia (temporary or permanent numbness). The inferior alveolar nerve of the lower jaw, which gives feeling to the lower lip and chin is usually the nerve treated like this.
Any of these procedures can be performed individually or together, depending on the situation.
This column is reprinted with the permission of the author and The Windsor Star. "Ask the Dentist" is written by Windsor dentist (and ECDS member), Dr. David Mady Jr.. The column appears the first Thursday of each month in the Windsor Star. Readers with questions can write to "Ask The Dentist", c/o The Windsor Star, 167 Ferry St., Windsor Ontario, N9A 4M5