Hello, friends and colleagues. I am Dr. Alfred Lau, specialist in oral and maxillofacial surgery. The topic of the lecture today is: The Use of Autogenous Bone Graft in Implant Dentistry. In our daily dental practise, we frequently come across situation where you may wish to place a dental implant but the volume of the bone is not good enough. It will give you a lot of headache when there is a 3-dimensional defect like this. The bone resorption goes both vertically and horizontally. And especially when there is an aesthetic zone where cosmetic demand is very high. Sometimes it could be a large pathological defect, such as this one after he had a cystic lesion being removed at the anterior mandible. If the bone resorption is at the posterior aspect of the mandible, you have an additional worry about the inferior dental nerve. When there is not enough alveolar bone, we could have basically two ways to go, if you are going for a dental implant treatment, namely, the graftless solution and the bone augmentation. Graftless solution means that you have ways to avoid putting implant at the non-ideal area where bone volume is not adequate, such as the Zygomatic implants where the anchorage of the implant are mainly at the Zygomatic bone. Sometimes we could put tilted implants, shorter implants, mini implants... all these are examples of graftless solution. For bone grafting or bone augmentation, there are some basics you have to know. There are three components that it is essential and important for a successful bone augmentation procedure. They are the bone cells, the scaffold which helps the bone cells to crawl and grow over, and the stimulus to induce the bone to grow into it. Autogenous bone grafting is the only option that gives you all these important components, namely, osteogenesis, osteoconduction, and osteoinduction. The general principles of bone grafting procedures are divided into six different steps. First, you need to harvest and prepare the graft, followed by preparation of the recipient bed. Fixation of graft is essential to let vascularization take place and thus proper healing. Tension-free soft tissue closure is the key to protect the graft and provide an excellent place for the graft to heal. We need time for the graft to fuse with the recipient site, most of the time start with inflammation, bone resorption and then bone remodelling. After all, we need to re-enter the site for any implant procedures. For instance, in this situation will be a dental implant placement. Bone grafting could be in any form, such as an onlay, inlay, buccal augmentation, vertical augmentation, etc. I will not try this heroic act to stack up bone blocks like this, because the failure rate is high most of the time mainly due to inadequate soft tissue coverage, wound contraction and exposure of graft and infection. You have to be very careful and critical with literatures saying these could be successful sometimes. It varies in different clinical situation of course. Let's look into autogenous bone grafting in details together. It is the only graft which consists of osteogenesis, osteoconductive, and osteoinductive effect, as I have mentioned before. There won't be any graft rejection and minimal chance of infection for this. However, the procedure itself is very technical demanding. You need to be trained and you have to have the skillful hands to ensure a good success. Many a times, autogenous bone grafting face a problem of more bone resorption when compared to biomaterials. Theoretically, the bone graft could end up 100% bone resorption if it is not being loaded after a period of time. There are a lot of different choices for bone harvest. These are common intra-oral choices. My favourite is a ramus bone harvest followed by a body of the mandible. Chin is also a good site to many surgeons, however I will put it at lower end as it could cause scaring and stretching over the lower lip region. Sometimes, it causes sensitivity over the mandibular anterior teeth too. It's only my personal preference of course since there are always pros and cons in different procedures. For extra-oral site, the anterior hip is the most commonly used harvest site. It is relatively easy and low morbidity. It could be as easy as a 30-minutes procedure under deep sedation and the patient can walk home on the same day after the surgery. This table summarised the relative volume of bone you could get from different sites. And the rate of resorption after healing. This explained why the choice of mandibular ramus and body of the mandible is my choice, since it has low resorption potential and relatively good volume of bone could be harvested. The maxillary tuberosity is an easy site for bone harvest, however small amount of highly porous bone is only expected and with high resorption rate afterwards. Clinicians need to balance the benefits and risks for different procedure in each individual clinical situation. This is another chart showing the relative amount of bone cells, growth factors in each type of bone you have taken regardless of the site. This is more for a reference since the majority of situation, the shape of the graft needed to rule the type of the bone graft you have to take, such as if you need augmentation of the thickness, you need a block. However, if you want to filled up an inlay defect, you may have to choose a particulate or cancellous type of graft. Autogenous bone harvest is still nowadays a gold standard for bone augmentation for these reasons listed here. There are numerous research to prove that biomaterials are very good indeed in many clinical situations nowadays. It could be beneficial since there are less morbidity and potential complication with the harvest site. And personally, I still trust and depend on autogenous bone graft for large bony defect and bone augmentation at the aesthetic zone, since some of the benefits could never be replaced by others. But don't forget you could also do a mixture of autogenous bone and biomaterials to acquire the benefit of both. With current bone augmentation techniques, the scope and possibilities of dental implant therapy are dramatically expanded nowadays. Thank you very much for your attention.
