Dental Implants and Bone Grafting, Site Preparation, Ridge Expansion Techniques
Unfortunately there are a number of patients who have insufficient bone for a routine dental implant placement. Resolution of these situations requires both a skilled and experienced dentist. Various bone grafting and site preparation procedures have been developed and used over the years with varying degrees of success. Basically, in deficient jaw ridges there is a need to either increase the width, the height, or both. With the exception of one particular situation it more successful to increase width than it is to increase height. The following is a description of the most commonly used procedures:
Sinus Lift
This is the most predictable of all grafts. It is used to increase bone height. The risks are minimal, the surgery is relatively atraumatic, the success rate very high, and the post op uneventful.
Dr. Kaiser performed his first sinus lift in 1982 under the supervision of the dentist credited with first describing the procedure. The technique has remained essentially unchanged except now Dr. Kaiser uses a piezo surgery unit that protects soft tissue and therefore reduces operative complications from 20 % to about 5 %. In most cases the dental implant, or implants, can be placed simultaneously with the sinus lift procedure thereby reducing time and cost. The exception is advanced sites in which the sinus lift is performed, and implant placement delayed four to six months.
Particulate Bone Grafts
This is probably the most common type of bone graft. This procedure is used to supplement both width and or height. The procedure may be done simultaneously with implant placement, although occasionally implant placement must be delayed for a few months. The problem with these grafts is the limited contact with the patient’s own bone forming cells, because the gum is peeled away from the bone ridge, destroying the bone forming cells that line the bone’s surface. Also, the graft material has limited contact with the patient’s own bone forming cells that remain within the confines of the bone ridge. Therefore, success is variable, and this is not Dr. Kaiser’s first choice.
Block Graft
In this procedure one or more large intact blocks of bone, are screwed onto the bone ridge. More successful than the previously described particulate grafts for large defects, it is still limited by lack of exposure to the patient’s own bone forming cells. These grafts are prone to shrinkage over time and post operative complications. Once again, this is not Dr. Kaiser’s first choice but sometimes this graft is unavoidable.
Socket Grafting
Although very common today after extractions, Dr. Kaiser has strong reservations about the usefulness when implants are to be placed. Dentists justify the socket graft to retain the dimension of the extraction socket until the implant can be placed. However, extraction sockets heal quite nicely without any supplemental grafting. Dr. Kaiser used the socket graft routinely until the early 1990s, and then he found a better way- simply place the implant immediately when the tooth is extracted. This procedure works just as well as placing a socket graft, because it retains the dimension of the socket, is faster and less expensive. This immediate placement works well for single rooted teeth. Molars are best extracted and left to heal, usually for about twelve weeks until an implant can be placed. Usually a socket graft is not required for molars.
Dr. Kaiser’s Preferred Procedures (To Avoid the Socket Graft and Onlay Bone Grafts)
Ridge Expansion
This procedure is used for mild horizontal bone deficiency. The gum tissue usually need not be peeled away from the bone ridge, thereby preserving the bone forming cells. Instead, a small opening is made in the gum at the crest of the ridge, and a narrow diameter drill is inserted to the proper depth. A series of gradually increasing diameter bone spreaders are inserted by hand, until the desired width is obtained. The advantages are: less time, less cost, less pain and the patient’s own bone is now all the way around the implant.
Ridge Split
This procedure is used for moderate to severe bone deficiency. Dr. Kaiser uses a piezo surgery ultrasonic unit that will not cut soft tissue which makes it safe for use close to nerve tissue. A very narrow cut is made in the crest of the ridge to the appropriate depth. The ridge is spread apart with wedges. The implant can sometimes be placed, but usually a particulate graft is inserted. An implant is placed later. The graft works well because it is now internal, well exposed to the patient’s own bone forming cells from all sides, unlike the particulate grafts and block grafts described previously.
Growth Factors
A couple of growth factors have recently become available, purportedly to enhance bone formation. They range in cost from modest to expensive. There is not enough information to make a strong recommendation for or against their use.