Block Grafts: Are These the Gold Standard or is the Long Term Viability Poor?

Autogenous block grafts are not the “gold standard”. Autogenous bone is considered the gold standard of bone graft materials as it contains viable cells (osteogenesis), BMP’s (osteoinduction) and a matrix for bone ingrowth (osteoconduction). More specifically autogenous cancellous bone is the ”gold standard”. Cortical block grafts from the chin and ramus are really not osteogenic as they contain few viable cells. However, cortical block bone grafting is a well documented technique for bone augmentation. Once a block graft incorporates into the site it becomes native bone. It is turned over into native bone by a process called creeping substitution (combined osteoclastic/osteoblastic activity). There is no such “higher osteoclastic activity”. Biologically and biomechanically the transplanted bone does not act differently than the native bone. It is curious to hear some clinicians claim block grafts don’t maintain implants long term. Rather than seeking “opinions” on the stability of block bone grafts research the clinical studies. Block grafts began with the Branemark group over thirty years ago. Nystrom et al (2009) followed maxillary onlay bone grafts in 44 patients for 9 to 14 years and found stable marginal bone levels with all patients still wearing there original bridges. Buser et al (2002) followed implants in cortical bone grafts for 5 years and found no additional resorption. There are numerous additional studies on implants in block grafts documenting long term stability. The Aghaloo and Moy systematic review found using intraoral bone for localized defect repair revealed a 100% implant survival. Additional studies on intraoral grafts have also found very high implant survival rates (96.9% – 100%) (Raghoebar et al, 1996; Von Arx et al, 1998; Sethi & Kaus, 2001; Cordaro et al, 2002; Zerbo et al, 2003; Levin et al, 2007). \

This topic was always going to be a bit of controversy as many things have moved on and there are many differing ideas. As far as I am concerned in my daily grafting cases I have not used any autogenous bone even a shaving in the last 8 years , if there is a block/chip that breaks off whilst creating the osteotomy I put it in the bin. A block is dead bone , it will be removed by osteoclastic activity or sequestrate thus leading to long term bone loss and hence loss of bone profile which can be an issue in the aesthetic zone . GBR especially with fully bio-absorbable synthetic materials can regenerate bone which appears to remain intact long term as it is essentially new rgenerated bone. Placement of the implant at the time of grafting appears to have benefits in graft stabalisation and improved results which I know is a hard idea to grasp when we are taught to place in solid bone. As to the osteoclastic presence concept this had been mooted back in the 80s initially , but with newer graft materials the increase the initial presence Osteocalcin , Osteopontin , Col type 1 Etc by being negatively charged ( Hunt and Cooper 07) which in turn leads to a significant increase of in Osteoblast presence the concepts have been more applicable. As to BMP , not available here in Europe , possibly for good reason as I read in the International Herald Tribune a few weeks ago that Medronic has been suppressing information on side effects with its use. As most dentists are using it off leiscence there could be issues. Anyway just another spin on things , backed up by many cases and 800,000 orthopeadic cases as well as some studies , ( Podoropolous 09 , Smeets 09 etc)

And yes harvesting does hurt a bit, sure I would not have it done on myself........ Regards Peter Sorry for typos again , must read through...

A bone block in general is not “dead bone”. A corticocancellous block has viable cells. A cortical block graft is non vital and does not contain many viable cells. The term “dead bone” therefore could be applied to any graft (autograft, allograft, alloplast) other than a vascular autograft. The block graft is not only removed by osteoclastic activity, it is remodeled in conjunction with bone deposition (hence the term creeping substitution – substituted by new bone). A block graft does not sequestrate unless it is not properly fixated. Cortical block grafts exhibit minimal resorption and as such are actually well suited for the esthetic zone. If a clinician is concerned with the stability of any graft in this area then slower resorbing materials (such as bovine HA) can also be used. I would think most clinicians would agree that for localized bone defects associated with implant placement, GBR is the preferred method for bone augmentation. The literature reveals that bone substitutes work extremely well in these types of defects (Aghaloo & Moy, 2007). Ridge augmentation for management of vertical and horizontal deficiencies is more challenging and many clinicians still advocate the use of autograft technquies. However, you imply that things have “moved on” and autogenous bone is not needed as there are “new” graft materials. This is contrary to the views of many clinicians (Buser, Jovanovic, Simion, Urban). Can you provide some information on ridge augmentation studies with these new materials (not localized GBR type defects or sinus grafts). I would be interested in clinical studies (dental, not orthopedic) on these new materials that document the volume of bone augmentation obtained (height, width), implant success/survival and long term stability of the implants and grafts - clinical case reports don’t count. I appreciate any well founded documentation on this “controversial” topic. P.S. Yes there is pain/morbidity associated with bone harvest and this will always be one of the main reasons we continue to search for alternatives. Some donor sites have more problems than others. Long acting local anesthetics, prophylactic analgesics and steroids help our patients manage quite well.

From a personal perspective, I had a ramus graft taken from my R ramus, fixated in the #27/28 site, followed by implant placement 4 months later and have 2 stable implants in place now for 9yrs. Overall, minimal swelling, minimal pain for a few days. From a practice perspective, I have used the ramus (more than the chin) when I need width predictably. Like the previous poster stated, good fixation of the block AND tension free flap closure and maintain the flap closed during healing results in a effective long term augmentation choice as the research has shown (for lateral augmentation.)

Hmmm, still waiting on those studies to support the use of those "new" graft materials to replace the need for sutograft for ridge augmentation...

With over 800 well documented cases ( many published ) including restoration of the extremely resorbed maxilla I am comfortable and Dr T was interested in experienced clinician opinions on blocks not blocks with membranes and particulates , not a first year diploma coursework. As for tradtional research there are numerous , from animal studies ( Podoropolous et al ) , to Multi- center studies ( Smeets et al ). Just looking to a better future for both patient and Dentist alike Regards Peter

Dr. T requested information on the long term viability of block bone grafting. You stated that you have not used autograft in the last 8 years and made negative comments about the biology of autograft. I was just curious if you could support your view on not using autograft in favor of these “new” graft materials you use. Case reports and animal studies are low level evidence to support a clinical technique. You may be comfortable with your results but we typically judge the merits of a technique or graft material by clinical studies and not “in my hands this has worked in over X number of cases” or “here is a case I did and it worked”. We have moved on from this subjective perspective and try to use science and evidence based dentistry to advance the field. I could not find a multi-center study authored by Smeets on bone grafting – only 1 animal study and 2 case reports. I provided studies to support the use of block bone and its long term viability. My intent was not to give you a homework assignment – only to give you an opportunity to share documentation to support your view. It doesn’t look like that exists… Impact of rhBMP-2 on regeneration of buccal alveolar defects during the osseointegration of transgingival inserted implants. Smeets R, Maciejewski O, Gerressen M, Spiekermann H, Hanisch O, Riediger D, Blake F, Stein J, Hölzle F, Kolk A. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009 Oct;108(4):e3-e12. A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation. Smeets R, Kolk A, Gerressen M, Driemel O, Maciejewski O, Hermanns-Sachweh B, Riediger D, Stein JM. Head Face Med. 2009 Jun 13;5:13. [Hydroxyapatite bone substitute (Ostim) in sinus floor elevation. Maxillary sinus floor augmentation: bone regeneration by means of a nanocrystalline in-phase hydroxyapatite (Ostim)]. Smeets R, Grosjean MB, Jelitte G, Heiland M, Kasaj A, Riediger D, Yildirim M, Spiekermann H, Maciejewski O. Schweiz Monatsschr Zahnmed. 2008;118(3):203-12.

Interesting debate guys. Dr C states the origin and therefore biological type of the block affects its performance. I can see that materials used in conjunction (fixation, support, space maintenance, protection, etc.) + technique and skill play a part so it’s a multi contributory approach. Radiolabeling studies by Muschler GF reported that very few transplanted cells survive from autogenous bone. Might it be that all grafts are essentially "non-vital" and as such we are gaining from the space maintenance, osteo conductive and possible osteostimulatory effects of the materials we use and the skills in which we use them? I agree with Dr C that we are moving away from the “here is a case that worked” mentality. Nevertheless, 800 successful autogenous free cases is highly interesting. More so if Dr F can show no case selectivity.

My comments on Autogenous grafts are not negative as it is the gold standard , it just appears as a number of clinicains do have issues despite the overwhelming research . This is a the situation that Dr T was refering to , and as harvesting is an issue for most patients to search elsewhere is only logical, as our patients are our primary concern. As I said I am happy as are my patients to be avioding the use of autogenous bone , the gold standard. As to research we know that papers cost money and there a very few true if any true randomised control trials ( the only standard for true research ) in dentistry . ( PS there is plenty mmore research on the marterial but alas no true RCT s so it will not sate your demands )

Dr. T stated, “Some experienced clinicians suggest the long term viability of the implant post block grafting is poor.” This is definitely not my experience and I presented studies to support this is not the case. My patients are also my primary concern and I go to great lengths to avoid complications and morbidity. I also want successful and predictable results (as do my patients). You state that you are happy to avoid using autogenous bone. I simply requested you support your use of other graft materials to accomplish cases that would typically be treated with block autograft (ie. vertical/horizontal ridge augmentation). I did not specify the research on these “new” materials had to be a true randomized controlled trials. This is the best level of evidence but these types of studies are few. I did note that case reports and animal studies are the lowest level of evidence. Any clinical studies on ridge augmentation with the materials you are using would do. When I work with graduate students I ask them to defend their approach to a case with literature to support their rationale. Can you share any clinical studies on your approach??

Each of us can quote our own statistics with regard to volume of bone regenerated and implant survival. The paradigm for any of these GBR procedures is that, with a well executed surgical procedure and respect for biologic principles, any of these graft procedures will perform well. I have outstanding results using block grafts with little or no resorption and great implant survival. Implant complications (crestal bone remodeling or implant loss) seem to occur more frequently with particulate materials as opposed to autogenous blocks. This has a rather simple explanation. There are dozens of different types of particualte grafts and membrane materials, some of which are far more effective than others. The resorptive patterns and remodeling to host bone of each of these can vary widely. The quality of both hard and soft tissue can therefore be affected and have significant consequences on implant survival. Autogenous blocks, on the other hand, have a defined mode of turnover and excellent retention of cortical zones. The choice of graft material for me is based on potential morbidity at the surgical donor site. Where possible, I will use a particulate material that resorbs completely and a longer resorbing membrane. These cases are usually single tooth with intact adjacent facial plates to help stabilize graft volume. As the deficient site increases in size, with a one-walled, rather than a three-walled defect, I will use either a block graft or titanium mesh. With regard to bone grafting, one size does NOT fit all. RJM

Very well put RJM. You add the perspective of the number of walls influencing the choice of augmentation technique and material. I agree with the choice of a particulate bone substitute and a longer resorbing membrane for localized defects with favorable defect morphology. The trend is towards using less autograft blocks (or autograft) with better graft materials (including membranes). However, autograft is invaluable when managing larger defects. You may have answered why Dr. Fairbairn is not using autogenous bone. I do not know his training or type of practice and it may be that he does not treat larger bony defects. It does not seem he is able to provide any clinical studies on the treatment of larger defects with “new” graft materials (without autograft).

Dear Dr.C , I have only placed implants for 20 years so am a relativly new to the practice and place only about 400 a year.I Was taught ( and still am) by my mentor who began placing in 1964 as well as developing his implant system in 1985. We treat all cases from simple cases( 3 walled ) , sinus augmentation , to extreme grafts where there is no buccal or palatal plate and restoration of the extreme resorbed ridge. I do show the cases globally , India next and have had many case studies published . I ahve also performed live surgery showing grafting techniques to a live audience . as to research , most is in the Spinal and orthopedic arena but as I said this is a newer direction ( I have recently modified a material for Dental applications ) and things take time, we cannot always look back . The full research catalogue can obtained from the 2 companies whose products we use and you will now those. Regards Peter

I have made my breakfast for over forty years and make over 300 a year – that doesn’t make me a chef : ) My point is we all have a clinical perspective built on our biases, training and experiences. Spinal and orthopedic grafting needs have some similarities to dental/maxillofacial applications but there are also vast differences. I just thought if you have not used autograft in 8 years you could substantiate your clinical approach with some clinical studies other than case reports. I agree we will welcome alternatives to autograft that will provide predictable results. Tissue engineering will undoubtedly change the way we practive in the future – I would just caution that we don’t jump on the “no autograft” bandwagon too early without research to back it up. Thanks for the interesting discussion.

Dear Dr.C I totally agre with taeching the value of autogenous bone and blocks etc , as that is what we did as you know I was offering a counter argument as a point of discussion and yes I do not uase any autogenous and in fact shun it , that is just the way we work and it seems very good but is only has 10 years of use thus I agree is theoretically untested . I too like sayings and practice can make a chef but you would definately not want Butch Harmon ( the best golf teacher and author ( researcher ) in the world ) to make that critical chip shot on the 18th to win the Masters , Tiger would be the guy I chose... Regards Peter