Stem Cells in Dentistry ?!?

Absolutely !!  Oral Surgery in general and bone grafting in particular are starting to make a transition.  More and more bone grafting scenarios employ cell-based or growth factor-enhanced grafting material.  Four items are absolutely essential in bone regeneration if predictable results are sought.

• A matrix or scaffolding (collagen, bone mineral, synthetic grafts)
• Cells (stem cells, platelets, osteoblasts)
• Signaling molecules (growth factors, morphogens, adehsion molecules)
• Time (often underestimated)

Within minutes after an “injury” to the bone structure, platelets aggregate in the area and release PDGF (Platelet Derived Growth Factor) and a variety of TGF-beta (Transforming Growth Factor – beta) molecules, to which BMPs (Bone Morphogenic Proteins) belong.  Some of the BMPs signal the Mesynchemal Stem Cells (MSCs) to “morph” into bone-precursor cells (osteoprogenitor cells).  Subsequently, PDGF signals these precursor cells to divide rapidly, in order to increase their number.  Once their number has increased (usually by an order of magnitude), a different set of BMPs will signal the precursor cells to “morph” again into mature bone-building cells (osteoblasts).

From this somewhat simplified molecular “injury cascade”, we can certainly appreciate the importance of stem cells.

A quick word on stem cells, because it has brought up some ethical and political issues in the past.  There are three types of stem cells in our body:

• Embryonic Stem Cells (most potent, can form every tissue in our body)
• Fetal Stem Cells (almost as potent, but somehwat more restricted in what they can become.  Often harvested from the umbilical cord and cryogenically frozen)
• Adult Stem Cells (a.k.a. mesynchemal stem cell.  This cell is already committed to form only tissues of mesynchemal origin, i.e. bone, muscle, cartilage tissue, etc.).

The embryonic stem cells are the ones wich caused all the ethical controversy and to this day we can not perform any experiments with this cell lineage here in the U.S.  This cell line is extremely potent and can form any kind of tissue from all three primitive germ layers.

Our interest, however revolves around the Adult or Mesynchemal Stem Cells.  It stands to reason that an increased number of such stem cells during an “injury” or bone surgery can not only improve but also accelerate the bone healing.  It is now possible to use stem cell-fortified bone graft material (several thousand times the cell concentration of the human body), for various grafting procedures.  This graft material is very expensive and must be delivered within a day of surgery.  Initial results look very promising across several research studies.

Osteoporosis, Bisphosphonates and Dental Implants

I have heard a lot of questions asked by dental professionals as well as patients regarding these topics lately.  The underlying question usually was: Do they mix?

Osteoporosis is a common disease characterized by decreased bone mass, increased bone turnover, and increased susceptibility to fracture.  In general, Osteoporosis itself is NOT a contraindication to having dental implants done.  Studies have shown that patients with osteoporosis enjoy the same kind of success rates with dental implants as patients without osteoporosis do.  What CAN present itself as a potential risk factor to dental implant surgery (and any kind of oral surgery for that matter), however, is the administration of Bisphosphonates (such as FOSAMAX®), which are designed to counteract the effects of osteoporosis.

Bisphosphonates belong to a class of drugs which inhibit osteoclast action and thus the resorption of bone.  This works well for maintaining good bone density (since the resorption cycle is being interrupted), however it can have disastrous consequences following bone surgery.  Bone will undergo a very structured healing response after surgery, which includes remodelling and turnover.  Osteoclasts play a very important part in this remodelling cycle of the healing phase.  If the osteoclast action is interrupted, osteonecrosis (bone cell death) may be a consequence.

Now not every regiment of bisphosphonates is a significant risk factor for post surgical osteonecrosis.  Up until very recently we have only haphazardly determined that injectable regiments of bisphosphonates or regiments of oral bisphosphonates for over three years present a definite contraindication to dental implant surgery.  Recently however, a test became available, which gives us a much more accurate way of determining the risk factor:  The CTx Test.

The CTx test, also known as the serum C-terminal telopeptide test, is a medical blood test that is used to assess the risk of bisphosphonate-induced osteonecrosis of the jaws.  C-terminal telopeptide is a marker used to measure bone metabolism. It is a by-product of normal bone metabolism or bone turnover.  If the CTx test shows a low value of CTx, then the implication could be that the bone turnover is low, thus the bone is less likely to recover from trauma, such as a tooth extraction or implant placement.  According to Marx ( J Oral Maxillofac Surg. 2007 Dec;65(12):2397-410.): “A stratification of relative risk was seen as CTX values less than 100 pg/mL representing high risk, CTX values between 100 pg/mL and 150 pg/mL representing moderate risk, and CTX values above 150 pg/mL representing minimal risk. The CTX values were noted to increase between 25.9 pg/mL to 26.4 pg/mL for each month of a drug holiday indicating a recovery of bone remodeling and a guideline as to when oral surgical procedures can be accomplished with the least risk.”   The latter portion of Marx’s statement implicates that any kind of Oral Surgery (including dental implant placement) could be an option, if a patient is taken off the regiment (under careful observation of his or her physician, of course) for about 3 months and a CTx re-test is taken for verification of new values.

If necessary, your dental professional or physician can order this test for you.  This test should be taken after 12 hours of fasting.

Why are dental implants not covered by dental insurances?

Dental implants have a very poor history with dental insurances. In fact, as of today I have yet to hear from a dental insurance that covers dental implants.

Now before I dwell on this too much, lets look at an example of a dental insurance here in California: Delta Dental – a reputable insurance company. When it first opened its doors in the 1960s, it gave its members on the average a $1,000 yearly limit. Now, mind you this was in the ’60s. At that time you could have had pretty much your full mouth redone for $1000, considering that the average crown price was about $60 back then. Now guess what the average yearly limit is today, over 40 years later? If you guessed $1,500, you were right. And the average crown price?? Well it ranges on the average here in California between $600 and $1,200. Can we all see the discrepancy here?

Now the average single tooth implant (which includes the surgical placement of the implant, the abutment and the final crown) is between $3000 and $4,500 on the average (go my website to find definitions and images for these components). As you can see, the economical challenges would be immense for an insurance company to overcome.

If insurance companies actually did cover dental implants, like they cover other dental work, they would eventually force doctors to accept a much lower payout for their implant work. That is very difficult to do, because implants and all the associated surgical and prosthetic hardware are very expensive to manufacture and purchase. Accepting a lower fee for implant services will lead some practices to “cut corners” in order to protect their profit margins and that is exactly what you don’t want to do with dental implants. They are very technique sensitive devices, and success rates could be dramatically reduced, if inferior products are being used.

I therefore take the position that dental insurances and dental implants are dangerous mix that should not be attempted. Many patients have found other creative way to finance such expensive work, like Care Credit or flexible spending accounts.

Technorati Profile

Hello Everyone!

This is my very first stab at blogging.  I am a trained clinician and therefore not the most computer savvy person, however I feel very strongly about acquiring this skill, because I have come to the conclusion that patients need and deserve a place where they can get an honest opinion about these relatively new areas in Dentistry.

Implant Dentistry and Laser Dentistry are very advanced forms of Dentistry, which can truly enhance and improve treatment opportunities for patients and make their treatment experiences a lot more comfortable.  Lasers for instance can be utilized to dramatically reduce any kind of discomfort during certain dental procedures – almost to the point where local anesthesia (shots) are not necessary anymore.  Dental Implants have been around for quite some time now, however this branch of dentistry is evolving at such a rapid pace, so that new treatment modalities are constantly being introduced.

All of the above mentioned issues, coupled with the fact that most patients receive more or less “cryptic” explanations about certain dental procedures in these sub-specialties of dentistry (or so I keep reading in blogs), have prompted me to start this blog.  My hope is that people find it informative and enlightening at the same time.  I welcome any kind of suggestions you may have, which can improve the quality of this blog.  I will do my very best to answer questions honestly and straight forward.  I will also post interesting articles and multimedia files to this blog.  Be aware though, that some of these files may be a little graphic in nature, since many of them are surgical in nature.

Thank You