by Larry Stein, DDS
Published in ‘Alert Diver’, March/April 2005*
More people are electing to have failing or missing teeth replaced by dental implants. I have experienced an increase in the number of questions related to dental implants and scuba diving in my capacity as a dental consultant for DAN, ScubaDoc and the Scuba Board. It is only natural because of the confluence of both diving and dental technologies that occurs within the mouth. Dental implants are found where the scuba regulator ends. Dental implants are associated the very same spaces containing gas that must be equalized during a dive.
This results in questions ranging from, “How long should I wait after implant surgery before diving?” to, “Will the pressure on the bite of my regulator affect the implants within my mouth?” First, here is a short history of dental implants.
There is archeological evidence that certain early civilizations attempted to re-implant lost teeth as well as those made of carved wood or ivory. In the eighteen hundreds, first gold and later, platinum implants were being placed into the human jaw. These proved to be unsuccessful. In 1937, Strock placed the first successful implants at Harvard University. These implants were made of a type of surgical stainless steel call Vitallium. This is a chrome, cobalt, molybdenum alloy commonly used in removable partial dentures. In 1948, Gustav Dahl reported the first subperiosteal implant. Then in 1967, Linkow, and Ralph and Harold Roberts introduced the endosteal blade implant. Finally, in 1981, the orthopedic surgeon, Dr. Per Ingvar Brånemark introduced the titanium, endosteal, root form, implant.
This final type of implant is the prototype of today’s most common dental implant. The key to the implant’s success is the use of titanium metal. In 1952, while Dr. Brånemark was doing bone-healing studies on rabbits, he inserted a small titanium plate with a lens attached into the bone of his experimental animals. This allowed him the peer into the bone and actually view the healing process microscopically. At the completion of the experiments, Dr. Brånemark attempted to remove the titanium plate, he found that the surrounding bone had fused to the metal. He called this fusion, Osseointegration. Through this serendipitous occurrence, successful dental implants and other implantable orthopedic devices would be possible. Obviously, in order to get an implant, one must first have surgery. There is surgery to extract a tooth and surgery to insert the implant. It might be necessary to graft bone into sockets to create a site suitable for the future implant and it might also be necessary to fill in part of the maxillary sinuses to give a patient enough vertical bone height to support implants in the upper back part of the mouth. Surgery is needed to increase
the bone height in jaws that have receded away and there may even be surgery at remote sites like the ileac crest to harvest large quantities of bone to build up the jaws. It is the surgery, the requisite healing period, and the prosthetics that affect patients who wish to scuba dive.
Generally, if there is a missing tooth and there are appropriate bone dimensions, a specially sized hole is made into the bone using precisely sized drills. Then the implant is threaded into it. A cover screw or a healing abutment is then screwed into the “top” of the implant. The implant is then allowed to osseointegrated for a period of between 4 to 6 months.
A cover screw is used when the implant is to be covered with a flap of skin during the healing period. The implant is then surgically re-exposed following the healing period and parts are then attached to the exposed implant to make it possible to restore. To avoid this re-exposure or second stage surgery, most surgeons are now using healing abutments that purposely project through the gums during the healing period. This abutment is simply unscrewed by the prosthedontist when the implant is ready to be restored. The appropriate parts are then added to render the implant restorable.
During the osseointegration period it is necessary to avoid anything that could apply pressure to the skin over the implant and cover screw or the healing abutment. It is possible for such pressure to create small movements or micro-movement of the implant. Such movements can disrupt the osseointegration process. Movements greater than 50-150 microns are sufficient to result in implant failure. If the bone dimensions are not adequate, then bone-grafting procedures are utilized to increase the height and width of the implant site. Natural bone can be obtained from shavings from the preparation of the implant surgical site, other parts of the mouth or even other parts of the body. This natural bone may be mixed with human bone from other sources, bone from other animals or even artificial “bone.” Whatever the source, this bone is grafted into the surgical sites both to stabilize the implant and to create an adequate height and volume of bone to contain the implant.
When a tooth is extracted, the site is usually allowed to heal from 3 to 6 months. Then the site is re-entered, the implant is placed, and the appropriate osseointegration period is allowed to occur. Many surgeons like to re-enter the site at about 3 months. There is maximum osteoid growth potential then which can be harnessed for osseointegration. Under the right conditions, an implant can actually be inserted into the extraction site on the same visit. This immediate implant protocol cannot be used for all extraction sites. When immediate implant placement can be used, the extraction site healing period is eliminated and the patient can have the restoration months sooner.
Diving should be avoided for as long as it takes to avoid complications associated with revascularization, stabilization of the implant, oral and sinus cavity pressure changes, ability of the patient to hold a regulator in their mouth, medications for pain or infection.
No hard and fast recommendations related to oral surgery and scuba diving has been developed. These recommendations are often related to wound healing physiology. Generally, the more complicated the surgery the longer the wait. Surgical complications will add to this time, as can any underlying medical conditions, tobacco use and alcohol consumption.
Gas exchange is partially a function of the vasculature of the local tissues. Simple extraction sites quickly develop a blood supply. Similarly, extraction socket grafting (socket preservation) also revascularizes rapidly. Diving following a simple extraction usually requires a 1—2 week recuperation time.
Bone grafting procedures and sinus surgery are more complex and will require a longer waiting period. The larger the graft site, the longer the wait. Six weeks to two months is a more likely time period to avoid diving. Even three months can be appropriate.
There are no documented medical guidelines regarding scuba diving and oral surgical recuperation periods! Patients will heal at their own rate no matter what “rules” we want to apply. This period might have to be revised according to how YOU respond to the surgery. Your surgeon should determine the appropriate time period. Even if your surgeon doesn’t dive, follow his advice. He is motivated by your welfare rather than your eagerness to return to diving. Donâ€™t wait until after your surgery to discuss with your doctor the nonrefundable reservations made months ago for a dive vacation on a live-aboard to Australia in two weeks.
You won’t like what he is going to tell you!
The quantity and quality of the underlying bone also affects implant/diving waiting periods. Some people have very hard, dense bone and others have soft, spongy bone. This affects the primary stability of the implant inserted into it. Implants placed into hard dense bone are less susceptible to micro-movements already described. The opposite is true for soft, spongy bone. Newly inserted implants are most vulnerable to movement within the first 2-4 weeks following surgery. The implants actually get looser within the surgical site before they begin to stabilize. Scuba diving must be avoided during the initial stages of osseointegration. A minimum of 5 weeks to two months is needed to just to render the implant stable. Longer times would be appropriate if substantial bone grafting has been done.
Diving too soon and applying pressure to the implant, no matter how slight, could cause sufficient micromovement that could lead to implant failure. If the regulatorâ€™s bite tabs are over the implant site, biting forces can be applied directly or indirectly to the healing implant. This may even occur to implants that appear to be out of bite. Applying pressure to teeth, flexes the jaws and this too, is a type of micromovement. Some doctors will recommend avoiding anything that causes micro-movement for at least 6 months. It can actually take up to one year for complete bone healing to occur in an implant site. While diving sooner than one year may not cause a problem, it will be up to you and your dentist or oral surgeon to determine your own risk tolerance.
Traditionally, an implant is placed and then allowed to integrate for a period of 4-6 months. Following this implant healing period (osseointegration), the final prosthesis, be it an implant supported crown, fixed bridge or fixed detachable denture is then fabricated. During this healing period, the patient would either wear nothing or some sort of temporary prosthesis that is generally not attached to the healing implant(s) such as a temporary removable partial denture. In the last several years however, protocols have been developed to help patients get into their final prostheses more quickly.
It is now possible to fabricate prostheses that are either put into use immediately or delayed only a few weeks. Generally, these immediate or early protocols are used when high initial stability of the implant can be achieved at the time the implant is placed. It is extremely important that excessive forces of abnormal magnitude or direction do not disturb the underlying implants.
Just because your surgeon and dentist has allowed you to wear an implant supported device sooner, it would probably NOT be wise to apply the additional biting load of a scuba regulator to the healing implants and the overlying temporary device. Again, micro-movement may occur and any temporary devices used which will usually be made of plastic and anchored with some sort of temporary cement or temporary screw. It would be safer to be more conservative and delay scuba diving until the final restorations are in place. Once dental implants are fully osseointegrated and the final prostheses have been placed, there is nothing inherent to scuba diving that would pose a threat to either the implants or the restorations. The spaces engineered into the implants to hold the overlying screws, abutments and prostheses are small and are completely contained within the titanium structure. There is no air space communication between the implants and the surrounding tissues. The implant structure is strong enough to withstand any pressure differentials that might occur if small amounts of gas were to migrate into these engineered spaces.
The overlying implant prosthetics can exhibit some of the same, extremely rare dental problems reported with scuba diving. Breakage of porcelain or cementation failures can occur and the use of implants affords no special ability of the overlying dental restorations to resist such failures.
Some implant-supported devices are cemented and as such, a cementation failure due to pressure changes is possible. This is a rare occurrence. Some dentists prefer to use a weaker, temporary cement under the final, permanent implant crowns and bridges. This allows for future removal of the restoration if deemed necessary. Other dentists treat the cementation to implants just like teeth and use permanent cement. Their philosophy is, “If I wasn’t worried about permanent cement for teeth, why worry about it for implants?” It would be wise to know whether your dentist has used temporary or permanent cement under your implant restorations. The likelihood of even the temporarily cemented prosthesis coming off is rare but you should be aware that it could become a problem.
Generally, if you have an implant restoration for over a year, in all likelihood, it will not fail as a result of a loss of osseointegration. However, there are other failure modes that can occur that are unrelated to the surgery, placement and healing of the implants. There are rare instances of implant breakage, abutment breakage, or retaining screw failures. This is usually associated with a very strong bite, trauma, poor treatment planning or a materials failure. Diving would not be the proximate cause for such failures. The increased use of dental implants makes it more than likely that some scuba divers will be participating with these devices. Scuba diving is not contraindicated for people who have had successfully healed and restored implants. There are certain aspects of dental implant procedures and restorations that would temporarily limit a diver’s participation in the sport. A thorough discussion with you oral surgeon and dentist should make your implants successful and your diving safe.
*Permission to print from Dr. Stein and DAN. Dr. Stein is an excellent source of information concerning dental problems as they relate to scuba diving. He is a valued consultant for Diving Medicine Online.