Bone grafting is a surgical procedure advised to rebuild or strengthen lost bone in the part of the jaw where additional jaw bone support is required often as a precursor to Dental implant placement.
In traditional style of implant placement if the jaw bone quantity is not proper and the available bone is not sufficient to accommodate an implant, additional surgical procedures like sinus lift and bone grafts will be recommended to increase the bone volume.
Bone grafts can be of several types:
- Autografts- where grafts are taken from the patients own body, usually from the chin or another part of the jaw.
- Allografts- here bone grafts are taken from a human donor, sourced from a bone bank.
- Xenografts- The bone grafting material is procured from animals, most commonly from Cows and Pigs and is processed to made compatible with human tissue.
- Alloplasts- This is a synthetic form of grafting material, materials such as hydroxy appetite and calcium phosphate are used.
In what conditions are bone grafts Required:
Generally bone grafts are used
- Immediately after tooth extraction to preserve the extraction socket, if tooth replacement is planned on implants in that site.
- Bone loss from tooth extraction
If the teeth are badly infected, especially in long term untreated infections, the infection surrounding the tooth roots will damage the neighbouring bone, leaving very little or no bone, this is when entire ridge augmentation will be required. - Sinus lifts
When the teeth in upper jaw, chiefly the upper premolars and first molar is removed due to some reason and not replaced, the sinus present above these teeth, tends to droop down leaving very little bone or no bone under the sinus to place an implant, that is when sinus lift surgery is advised where the pneumatized sinus will be lifted back to its original position, bone grafting done under it and left for few months for it to heal,this is then followed by implant placement. - Bone atrophy due to dentures, dentures cannot prevent bone loss, they infact increase the rate at which the bone resorbs due to the constant pressure they exert on the bone.
- Cyst and Tumours.
- Injury or trauma.
- Congenital defects.
Pros and Cons associated with bone grafts:
1. Auto grafts where the grafts are taken from the patients own body which involves the patients own bone tissue. Bone grafts will be taken from the another part of jaw like the Ramus of the mandible, the chin, hip or leg.
Pros :
- Lower chances of rejection or infection as it is taken from the patients own cells which support Bone growth.
- Osteogenic property that is the ability to promote new bone formation will be better.
Cons :
- Involves multiple surgeries, one at the donor site from where the bone graft has to be extracted an then again at the site where the grafting has to be done leading to increased pain, recovery time and risk of infection. The bone recipient site is left for a period of 3 to 4 months for the bone to integrate, which is followed by implant placement.
- Limited amount of bone graft can be extracted.
2. Allografts, here the bone tissue is taken from a human donor (cadavers) not the patient himself, and then processed and sterilized.
Pros:
- This type of bone grafting can restrict the treatment to only one surgery there by reducing the recovery time and pain.
- Large quantities of graft can be harvested.
Cons:
- Risk of rejection as the donor is a foreign body.
- Due to the absence of living cells(cadaver)the grafts rely on patients body to integrate with the bone.
- Possibility of disease transmission.
- Many people will not be ready to accept bone from a dead body.
- Carries the possible risk of bone transplant rejection and infection which will be ask for
repetition of the grafting procedure.
3. Xenograft, Graft from an animal source, usually bovine, cow or pig\porcine
Pros:
- No secondary surgical site required.
- Large quantities of graft can be procured.
Cons:
- Delayed healing.
- Absence of living cells.
- Potential risk of infection and bone graft failure.
- Not favoured by many due to religious reasons.
4. ALLOPLAST (Synthetic bone grafts), generally created from ceramics such as calcium phosphate, bio glass or calcium sulphate.
Pros:
- Single surgery.
- Sufficient quantity of bone graft can be derived.
- No risk of disease transmission.
Cons:
- Might not integrate properly with the natural bone due to the absence of living cells.
- May not provide the required density to support an implant.
Apart from the additional expenditure and delay in the treatment time they might not be fruitful in many of the instances giving rise to pain, swelling, fever with chills and there are every chances that the body might reject the grafts making it necessary to repeat the procedure and delay the replacement of teeth further.
Alternatives to Bone Grafting
When there is a possibility to place implants in your natural Bone which will be much more superior in quality when compared to the grafted bone and when placing of Implants in your own native bone is achievable even in highly resorbed jaw bones with a simpler straight forward approach which promotes faster healing and a higher, long term success rate and fix permanent teeth on implants immediately without waiting for months together, there is no necessity to undergo bone grafting or other additional surgical procedures like Sinus lifts for IMMEDIATE LOADING of teeth on Implants, there is absolutely no necessity to undergo any other added procedures like Bone grafts.
Placing implants in jaws with sufficient bone is not an issue but real challenge arises when the bone quality is not proper.
The quality of the bone when presented in the descending order of quality, the lower anterior jaw bone ranks the best, followed by the upper anterior jaw, followed by the lower posterior jaw bone and finally comes the posterior section of the upper jaw bone, the upper rear jaw ranks least in the quality due to the presence of Sinus, which are air filled spaces present on either side of nose and above the premolar and molar teeth.
Reason for poor bone quantity in the upper and lower distal region
When infected teeth are retained for long without any treatment, the infection surrounding the tooth roots damages the neighbouring bone finally resulting in very less bone or no bone under the sinus making it difficult to accommodate an implant there, in the second instance if the teeth present below the sinus are removed and not replaced on time, the sinus pneumatizes resulting in bone resorption, in either of the instances there will not be sufficient bone left for implant placement, that is when additional surgical procedures like sinus lifts and bone grafting are under taken where the sinus is lifted back its original position and bone added under the sinus and left for few months for it to integrate with the tissues, to support an implant.
When it comes to replacement of teeth with implants in the lower jaw, the anterior segment bone quality will be superior and this region will not have any major nerve or blood vessels so will not pose any problem for implant placement in most of the cases. A major nerve called the inferior alveolar nerve traverses in the posterior segment of the mandible and ends in the premolar area that is almost half way through.
When the bone height is proper, implants can be planned in the bone present above the nerve and in the anterior segment without any concern. But when there is no sufficient bone left above the nerve in the posterior section, that is when complicated procedures like nerve repositioning is done where as the name suggests, the position of the nerve in changed and bone grafted to accommodate implants in the posterior section of the mandible.
How is it possible for full mouth rehabilitation on implants without subjecting the patients to sinus lifts, nerve re positioning or bone grafting in compromised cases where the Bone quality is not proper.
When infected teeth are retained for long without any treatment, the infection surrounding the tooth roots damages the neighbouring bone finally resulting in very less bone or no bone under the sinus making it difficult to accommodate an implant there, in the second instance if the teeth present below the sinus are removed and not replaced on time, the sinus pneumatizes resulting in bone resorption, in either of the instances there will not be sufficient bone left for implant placement, that is when additional surgical procedures like sinus lifts and bone grafting are under taken where the sinus is lifted back its original position and bone added under the sinus and left for few months for it to integrate with the tissues, to support an implant.
When it comes to replacement of teeth with implants in the lower jaw, the anterior segment bone quality will be superior and this region will not have any major nerve or blood vessels so will not pose any problem for implant placement in most of the cases. A major nerve called the inferior alveolar nerve traverses in the posterior segment of the mandible and ends in the premolar area that is almost half way through.
When the bone height is proper, implants can be planned in the bone present above the nerve and in the anterior segment without any concern. But when there is no sufficient bone left above the nerve in the posterior section, that is when complicated procedures like nerve repositioning is done where as the name suggests, the position of the nerve in changed and bone grafted to accommodate implants in the posterior section of the mandible.
Fixed teeth on implants using Conventional Implants is possible using “ALL ON 4” and “ALL ON 6” Concept. “ALL ON 4” concept where four implants are placed in each of the jaws and temporary interim prosthesis given immediately, which can be later be changed into permanent prosthesis, this procedure is possible in most of the jaws as the quality of the bone will be good enough in the anterior segment as mentioned before. But the chief concern with All on 4 being, all the 4 implants are accommodated in the anterior and middle segment of the jaw and not spread out uniformly through out the jaw, in other words, Two implants on either side of the midline and the other two implants before the sinus on either side in the upper jaw and like wise two implants on either side of the midline and two implants on either side before the main nerve ends will be planned in the lower jaw.
The posterior segments of both upper and lower jaws will be devoid of implants as shown in the x ray above and therefore the grinding teeth will not have any implant support, these are called as cantilevers. Cantilever in other words is something that is supported on only one end and left unsupported on the other end.
The grinding teeth bear the maximum brunt of the grinding forces and for that reason need extra support, which will be lacking in “ALL ON 4” system, this might pose problems for the implants due to additional burden in the long run.
Benefits of all on 4 procedure
- No sinus lifts, no bone grafts.
- Economical.
- Addresses all the problems related to traditional removable dental
Disadvantages
- Permanent teeth cannot be immediately loaded in most of the cases.
- Cannot avoid cantilevers, which is a major cause of concern.
- There are chances of implant failure due to additional burden on the distal most implants.
“ALL ON 6” overcomes the disadvantages associated with “ All on 4” technique where implants are also placed in the distal end of the upper and lower jaws to distribute implants uniformly through out the upper and lower jaws to provide proper stability to the restoration, to increase life span of the implant and also to avoid cantilevers.
The question now is how to to place implants in the distal end of the upper and lower jaws without sinus lifts and bone grafts.
Like in “All on 4” concept, four implants will be placed anterior or mesial to the sinus and the last two implants that is the fifth and the sixth implant will be placed in the Pterygoid bone present behind the upper wisdom teeth on either side, there by providing a proper symmetry in Implant placement.
Pterygoid bone is a very hard and rigid bone, engaging this bone will provide proper stability and balance to the restoration, placement of implants in the Pterygoid bone is mandatory even if the bone below the sinus is proper as the bone present in this region is far more superior than the bone present under the Sinus.
Benefits of Pterygoid implants:
Pterygoid implants are specialized dental implants placed in the Pterygoid region of the maxilla. They are particularly beneficial for patients with severe posterior maxillary atrophy or sinus-related challenges.
1. No Need for Bone Grafts
- Pterygoid implants eliminate the need for bone grafting procedures like sinus lifts or
block grafts, saving time and reducing complexity.
2. Immediate Functionality
- These implants allow for immediate loading, enabling quicker restoration of chewing
function and aesthetics.
3. High Success Rate
- Anchored in the dense cortical bone of the pterygoid region, they provide excellent
primary stability and a high success rate, even in cases with significant bone loss.
4. Cost-Effective
- Avoiding additional grafting procedures reduces overall treatment costs and
minimizes surgical interventions.
5. Minimally Invasive
- The procedure is less invasive compared to extensive grafting surgeries, resulting in
reduced post-operative discomfort and faster recovery.
6. Restoration of Function in Challenging Cases
- Pterygoid implants are ideal for patients with extensive maxillary atrophy where
placing of implants may not be viable.
8. Biomechanical Advantages
- Placement in the Pterygoid region ensures optimal load distribution, reducing stress
on the implants and increasing prosthetic durability.
In the lower jaw if there is no possibility to place an implant in the remnent bone present above the nerve, instead of resorting to nerve repositioning and bone grafting, a technique called nerve by pass can be done done, though this procedure requires expertise and experience it provides desired stability to the implants as Bicortical engagement of buccal and lingual bone is done.
Hence along with four implants as in all on 4 concept two implants placed in the rear region of the lower jaw will serve our purpose of providing long term stability and permanence the Implants.
How do we manage cases with
In few cases there will not be sufficient bone anterior to to the sinus on one or both the sides of the upper jaw, such cases when there is no possibility of placing an implant before the sinus, a zygomatic implant can be planned, this implant is placed in the zygomatic bone or cheek bone which is rigid and not prone to infections of the jaw bone. This implant might be required in one or both sides of the jaws based on the amount of bone resorption, this zygomatic implant along with two Pterygoid implants and two implants in the anterior part of the bone on either side of the midline will support the restoration and serve one for his lifetime when properly executed.
Benefits of zygoma implants
1. Done under local anaesthesia.
2. Eliminates the requirement for sinus lifts and bone grafts.
3. Reliable solution.
4. Aids in immediate loading of teeth.
5. Used in conjunction with other implants.
6. High success rate.
Absolute no bone cases
There are few cases where there will be absolute no jaw bone due to long standing infections and also in case of trauma, tumours, developmental deformity or infections like Black fungus or even denture wearers, where the dentures just sit on the gum and do nothing to arrest the bone loss due to lack of stimulation to the bone from grinding forces and bone loss also due to the constant pressure exerted by the denture plates on the bone so in such cases there will be complete loss of upper jaw bone and placement of implants in the upper front region will also become not worth considering, in such highly resorbed cases, Zygoma implants comes to the rescue, here in such cases the cheek bone will be engaged to place two Zygomatic implants on each side, these four Zygomatic implants along with the two Pterygoid implants will aid in immediate loading of permanent teeth without resorting to any other surgical procedures.
Full mouth implantation can be achieved in any bone condition and permanent teeth fixed in less than a week without subjecting the patient to any additional surgical procedures.
