Narrow Ridge Defect in Maxillary Anterior Region Part 1

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Posted on By Maurice Salama In Bone Grafting

Narrow ridge in area of Maxillary Central Incisor. Critical size defect as implant in area would be completely out of bone. Which way to go? Ridge Split, GBR, BMP-2, Ti-Mesh or Block Graft? Immediate or Staged Approach? Thanks. Dr. Salama

Block Graft
CBCT 3D

Harvest Site
Narrow ridge


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27 Comments

Today's case. Wisdom teeth removed and block harvest same surgery. Dr. S


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A great service for our young patients with congenitally absent teeth or tooth loss due to trauma. Just when they are of age for implant placement they also often need their third molars removed. Beautiful surgery and documentation Thanks for sharing this technique (I tell the parents it’s a “two for one special”).

Misch CM. The harvest of ramus bone in conjunction with third molar removal for onlay grafting before placement of dental implants. J Oral Maxillofac Surg 1999;57:1376-1379.


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Other approaches could be used, like ti-mesh and bmp2, but in this particular case, with the necessity to remove the wisdom tooth, this is the best way to resolve the case.
Sormani.


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Craig and Sormani; Thank you both for the kind comments. I agree and thanks to great literature by people like you Craig, this still seems to be the best and most successful option of all. Despite the tendency to approach with other techniques, this one still seems to be the best approach and least expensive. thanks for the comments Maurice


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Maurice, Nice solution and well executed. I am not particularly fond of block grafting because of the donor site and length of time for bone remodeling. However, I must agree you have "properly played the hand you were dealt". Can't let nice piece of bone go to waste. In my opinion, an EXTENDED DELAYED approach is best here. Thanx for sharing another interesting case. Chuck.


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Beautiful case. When extraction of impacted tooth is considered, this augmentatation is the best..I think that mesh can be alternative to block bone when ext is not considered..What do you think about allogenic block in this case, Maurice ?
Thank for sharing..DS


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Maurice, very nicely done.
I think that when the bony horizontal defect is big and the existing bone is almost compact cortical with minimal medullary part, autogenous block will act best as allogenic block needs more blood supply after perforating the buccal plate to completely remodel and be replaced by the patient own bone.while for the autogenous bone, blood supply is only required to achieve bonding at the interface between the block and the existing bone as the autogenous is a living bone.

I would appreciate Maurice, Craig, Sohn, Sormani and Chuck ideas in this regard ?

Omar


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Omar and DS; I think we get better remodeling with autogenous bone than allograft blocks. I leave 4 months for re-entry with autogenous and 8 months for re-entry with allograft blocks. Would not utilize allograft blocks for vertical augmentation ONLY horizontal. The vertical component always seems to remodel and resorb. In general, always more long term remodeling changes with allograft blocks.
Thanks for all the great comments Dr. S


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Omar, I completely agree with the recent comments Maurice made. As I’m sure you know all free bone grafts must become revascularized to incorporate into the recipient site. An autogenous cortical block bone graft is mostly non-vital bone. It must revascularized along the existing haversian system. This is accomplished by osteoclasts/osteoblasts (cutting cones) associated with newly forming vessels. Implants may be placed at four months even though the graft may not be completely remodeled into new bone (it is still an admixture of new vital and old non-vital bone). The obvious advantage in this case is that you have to expose the donor site anyway to remove the third molar so you are not adding morbidity.
An allogeneic block could be considered in a case like this (horizontal). However, the resorption of allogeneic blocks is greater and I find somewhat unpredictable (especially with vertical augmentation). I have been using allogeneic blocks with rhBMP-2 and have been pleased with the results to date.
I am confused with Chuck’s comment the concern for “length of time for bone remodeling” for block bone grafts. Block bone grafts require less healing time (4 months) before implant placement than GBR when used for ridge augmentation and staged implant placement. Studies have found that a four month healing time is adequate and complete bone turnover into new bone occurs in about seven months. (Zerbo IR, deLange GL, Joldersma M, et al. Fate of monocortical bone blocks grafted in the human maxilla: A histologic and histomorphometric study. Clin Oral Implant Res 2003;14:759-766).


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Craig, I believe you already stated the answer to your own question. In general there seems to be a random (unpredictable) mixture of vital vs. non vital bone over time when using block grafts. The real question is whether the block graft is being INCORPORATED by vital bone or actually REPLACED by vital bone. Chuck.


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Chuck, I think you may have misinterpreted what I wrote. I never said autogenous bone graft replacement was random or an unpredictable mixture of vital/non-vital bone over time. The graft replacement is organized and complete over time. An autogenous graft is replaced by creeping substitution. It begins at the recipient site interface and extends throughout the haversian system of the graft. I did say the allogeneic bone graft remodeling appears more unpredictable. I'm not sure about your "real question" - the block autograft is replaced by vital bone via creeping substitution. This is the definition of graft incorporation with the host.


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Craig, This a very interesting and important discussion. I wasn't quoting you in regard to the random distribution of vital and non vital bone in a block graft during the remodeling process. Those were my words. However, I do reference Joseph Choukroun in saying the vascularization of a block (allograft or autogenous) is random. In addition,I believe vascularization of a particulate graft is more efficient than a block. Therefore, I would expect the the remodeling process of a particulate graft to be predictably faster and more efficient than a block. I would like to agree with what you are saying, but now you have me confused by your interchangeable use of the terms replacement, substitution and incorporation. Thank you for such a stimulating and thought provoking discussion. Chuck.


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Chuck, rather than referencing an individual that has done no published research in the area I would prefer to reference studies that have actually examined the process. I can provide more studies that have scientifically examined autologous bone graft healing.
It has been shown that cancellous bone grafts revascularize faster than cortical bone grafts. It is simply easier for the vessels to grown into a looser network of trabeculae than the microarchitecture of a block’s haversian system. As such particulate grafts would also be easier to revascularize (if they are not packed too dense). A graft may revascularize faster but may not allow implant placement sooner. For example a cancellous bone graft is allowed to heal for six months before re-entry compared to four months for a cortical block. This is due to the time it takes for developing graft remodeling, maturity and density. The same could be said of the GBR process. Guided bone regeneration is a time dependent process - smaller defects fill faster than larger defects. It takes time for the regenerated bone to mature and improve in quality for implant placement. The cortical block has the benefit of denser bone allowing implant placement earlier – even if it has not fully turned over into vital bone.
I may be interchanging terms but I do not imply they all mean the same thing. Replacement – a “free” non-vital cortical bone graft is replaced with vital bone over time. Creeping substitution is substituting old bone for new bone via cutting cones (osteoclasts/osteoblasts). Incorporation simply means the graft has become embodied within the host tissue. Technically it does not have to be replaced or substituted. However, with a cortical bone autograft it is replaced and substituted by new vital bone. I hope this clarifies my views. Thanks for the exchange.


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Craig, Thank you for the clarification. I now believe we are in agreement. On another note, just because Dr Choukroun (or anyone else) hasn't published in a particular area doesn't mean he is wrong. As a matter of point, I believe his statement is consistent with what you have just stated. In addition, published research is open to interpretation. Best regards. Chuck.


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Chuck, no disrespect to Dr. Choukroun. My point is I would rather reference published studies on a topic than quote someone that isn't well known for their work in a particular area. The published work has gone through a peer review process.
Just because it is in print doesn't mean it is right - and just because someone hasn't published doesn't mean their view is wrong. You are right - any publication is open to interpretation (and not always the intended perspective!). However, I don't agree that Dr. Choukroun's statement is consistent with my statements. Revascularization of an autograft is not random process. It is controlled by growth factors (such as VEGF) and oxygen tension differentials in the tissues. Revascularization of an autograft begins at the graft-recipient site interface and penetrates the graft until completion. I would not characterize this as a "random" process - the biology of wound healing is a well controlled process. I think we lost everyone else in our academic discussion LOL.


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Craig, no worries. We are following up a very interesting and benefecial discussion in a current topic.
Back to my previous statement, I found you do agree with my point that for autogenous block graft it is only necessary to achieve autograft replacement by vital bone through creeping substitution (at the interface). At this stage the graft is stable enough to place the implant while the remodeling process is ongoing. My point is that added to the equation of the influence of the type of the bone graft e.g autogenous, allogenic, particulate, the quality of the bone at the receipient site plays a significant role also. When the bone at the receipient site is almost cortical (less vascularized) the creeping substitution is much slower for that reason allogenic block is not working equally good to autogenous as it resorb faster.

Thank you for dental xp and for your time in a wonderful discussion that put as at the edge of such important topic.

Omar


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Omar, your statements are correct – initially the replacement occurs at the interface and implant placement is possible as the graft is stable. You bring up an interesting point – does the quality (density) of the recipient site bone influence graft incorporation? Your premise is that a dense cortical base would be less vascularized so the graft would not heal as well compared to a less dense base (cancellous or thin porous cortical). This is one reason it is recommended to perform cortical perforations of the recipient site when there is a dense cortex. This opens channels into the vascular medullary bone and may improve revascularization. The trauma to the recipient bone also releases growth factors (RAP) and improves the union between the graft and host bone.
Your next point applies this concept to healing of an allogeneic block bone graft – it may resorb more than an autogenous block due to slower revascularization. This question is more difficult to answer. There are few studies that have actually measured autograft resorption. I am not aware of any studies that have measured allogeneic block resorption except for Keith et al, 2006 (and their results are questionable – they only estimated a % of graft resorption and did not actually measure it). I believe there are several reasons we see greater and more unpredictable graft resorption with allogeneic blocks. One reason is that most allograft blocks are from the iliac crest. They have a thin cortex and a thick cancellous component. This microarchitecture leads to greater resorption as cancellous grafts resorb more than denser cortical grafts. Another obvious reason is the allograft has no vital tissue. It is simply a scaffold for bone ingrowth. This is why most clinicians insist on using barrier membranes over the allograft block. The allograft is desiccated and brittle. This can result in handling problems and microfractures during placement. The inductive capacity of an allograft may be affected by the manufacturing process as well. Thank you for your comments.


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Gentlemen; This discussion was simply outstanding. Civil and Respectful but also Scientific and Clinically based and providing clarity to what we have been seeing in our own clinical cases like this one for many years. I enjoyed the review by Dr. Misch on his last post as it pertains to the possibilities of how host bone responds to the graft depending on it's own native vascularity.
Another point to complete the review of all this is the impact of "timing" of implant placement and the response of the "grafted" bone to the secondary trauma of drilling the implant? How do we feel this impacts the graft and the biology of healing and remodeling?
Dr. Salama


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Thanks Maurice. I have enjoyed this discussion as well. You bring up another important aspect on the grafts incorporation into the recipient site. Many of us emphasize the importance of maintaining blood supply to the healing onlay block graft. Reflection of a full mucoperiosteal flap during implant placement may disrupt the blood supply and create more resorption. This is why we typically remove the fixation screws through small incisions over the screw head rather than reflecting a full flap. The secondary trauma from the implant osteotomy releases additional growth factors via the RAP phenomenon. There is further remodeling of the bone around the implant as the surface becomes osseointegrated. The implant itself stimulates and maintains the surrounding bone. This is one reason the argument that an onlay bone graft will continue to resorb over time and “melt away” causing bone loss around a dental implant makes no sense. By the time the implant is integrated and loaded the “graft bone” has been replaced by new vital bone. It no longer acts like a “graft” as it has been incorporated into the host and is “native” bone. Clinical studies have confirmed the long term maintenance of onlay bone grafts around dental implants. 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 their 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.


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Craig and chuck an interesting discusssion. I don't think I have to add anything I think you both know which way I would go in this case. Craig one question I have about the Nystrom et al 2009 study is how did they measure the bone. was it with PA's or with CBCT or was it an open inspection. THereason for my question is that I found in many of my solid block cases I did get resorbtion of the buccal bone over time when I checked with a CBCT. And even though the implant was in function it did not retain the thickness of buccal bone that I had previously. What is your experience with this. This is one of the reasons why I have switched to the veneer type grafting as you get a more vascularised bone than you would with a solid block


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what a discussion, i enjoyed it. thanks Maurice for sharing, tnx Craig and all other colleagues for your comments. really enjoyed it
Dr Moghaddas


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Truly the best option here. Keep us posted Mo.
x


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Maurice. Comparing the original Bone and PRGF image to the 6 month healing image (related post above right), It appears the pattern of bone regenerated is a "mirror image" of where the particulate bone/PRGF was placed. The "void" appears to mimic where the block graft was placed. What are your thoughts? Is that how it appeared to you clinically? Chuck.


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Dr Salama,

Did you use a barrier in this case?

Thanks,

Ehab


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Chuck and Ehab; I found this case to turnout quite well. There was some minor resorption around the coronal fixation screw....1-1.5mm which often occurs when we wait more than 3-4 months for implant placement and is not predictable. I did not use collagen barrier only PRGF Fibrin. This minor resorption did not effect the outcome of the case as I had a robust ridge to place my implant. regards Maurice


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No doubt ....this is the treatment of choice .and Very nicely done. The bone block will work perfectly if horizontal augmentation does not exceed 4 mm....if so ...i will keep the autogenous graft choice but will shift for khoury plate technique ...at least it works better in my hands..thank you Maurice for sharing, and thank you all for this valuable discussion ....viva Dental xp


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Emad; Well stated my friend. See Part 2 to observe the outcome. regards Maurice


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