A little bit on bone grafting…

The topic of bone grafting seems to be one of the more confusing areas in implant dentistry.  When do I need it, why do I need it and why is it so darn expensive?  Generally a bone grafting procedure is needed whenever there is insufficient bone available to place a dental implant of proper dimension.  Bone will resorb over time in the areas where teeth are missing.  I still don’t believe that patients always get the best explanation as to what the graft options are and what the pros and cons are – well, hopefully this little blog will shed some light on this topic.

For starters, let’s just quickly review the different classifications of bone grafts.  All bone graft materials can essentially be classified into the following classes:

  1. Autografts
  2. Allografts
  3. Alloplasts
  4. Xenografts
  5. Growth Factor Enhanced Grafts

Now, all of these five classes can have either or both of the following properties:

  • Osteoconductive – the ability to “guide” bone cells
  • Osteoinductive – the ability to accelerate bone regeneration

    A typical autograft from the chin

    A typical autograft from the chin

Autografts are bone grafts, which come from your own body.  This type of graft is still considered the “gold standard” by many surgeons.  It offers the best of both worlds; it has very good osteoconductivity and also great osteoinductivity due to its high content of resident growth factors.  The disadvantage is the higher morbidity.  It is always necessary to conduct a secondary surgical access in a remote location of the body in order to harvest the bone.  Depending on the quantity of bone needed, this can be the hip (for larger quantities) all the way down to an intra-oral site, such as the chin or the back of the jaw.  Autogenous bone grafts have shown to be some of the most predictable grafts in surgery.

A typical allograft from a bone bank

A typical allograft from a bone bank

Allografts are a close relative of the autograft, in that it is of human origin, usually cadaver bone from a bone bank.  This always sets off a red flag with people with respect to disease transmission, however with the tight screening protocol and advanced processing technology this is virtually unheard of in the United States.  Allografts have the big advantage that they do not require a secondary surgical access site, however, they also have predominantly osteoconductive properties and very little if any osteoinductive properties.  Graft assimilation and maturation takes therefore longer than with the autografts.  Grafting success rates have also favored the autografts by a slight margin, depending on the individual application.

A typical xenograft of bovine origin

A typical xenograft of bovine origin

Xenografts are bone graft substitute from a different species all together, usually from bovine origin.  These grafts have usually only osteoconductive properties, since the organic portion has been completely removed (so no, there is no chance to contract BSE a.k.a. Mad Cow Disease).  The advantage of a xenograft is that there is a large quantity of bone available for the screening process for an exact micro architecture that is needed.  Their osteoconductive properties are therefore very good.  It can be distributed in particular form or as blocks.  Xenografts have shown to generate astonishing results, especially in sinus lift surgeries, which are often necessary for the placement of dental implants into the back areas of the upper jaw.

An example of recombinant human growth factor

An example of recombinant human growth factor

Growth Factor Enhanced Grafts are very new on the market.  These grafts capitalize on the regenerative powers of human growth factors such as Platelet Derived Growth Factors or Bone Morphogenic Proteins, both of which are generated by our own body during a bone repair and remodeling cycle, however these grafts are manufactured with recombinant DNA technology and are very concentrated.  These growth factor formulations are usually in liquid form that need to be combined with a “carrier”, such as collagen or a calcified matrix.  These grafts offer very good success rates, but their caveat is that they are VERY expensive.  This is an important point to consider, because more often than not, they just accelerate the graft assimilation and maturation time.  Research has yet to show whether the bone quality differs between all these different graft materials after a year or two.

Well, I hope this was informative for you.  I will be available for questions and comments, so don’t hesitate to post.

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One Response

  1. […] keeps the membrane “tented” up.  For more detailed information on bone grafts see my bone graft post or link to Robert Gougaloff ’s website.  This bone graft will then “mature” over […]

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