Stem Cells in Dentistry

Until recently, stem cells harvested from umbilical cord blood were the only option to guard against future illness or disease. Although stem cells from human exfoliated deciduous teeth (SHED) are comparatively less potent than embryonic stem cells the cord cell harvesting and storage process is unfortunately beyond the reach of many people.

Because of its advantages of an abundant cell supply and painless stem cell collection with minimal invasion, banking ones own tooth-derived stem cells is a reasonable and simple alternative to harvesting stem cells from other tissues.

SHED was discovered in 2003 by Dr. Songtao Shi. In 2004, scientists at King’s College London discovered a way to cultivate a complete tooth in mice and were able to grow bioengineered teeth stand-alone in the laboratory. Researchers are confident that the tooth regeneration technology can be used to grow live teeth in human patients.

Obtaining SHED is simple , convenient and involves little or no trauma. Every child loses primary teeth, which creates the perfect opportunity to recover and store this convenient source of stem cells – should they be needed to treat future injuries or ailments and presents a far better alternative to simply discarding the teeth or handing them to the ‘tooth-fairy’. Furthermore, using ones own stem cells poses few, if any, risks for developing immune reactions or rejection following transplantation and also eliminates the potential of contracting disease from donor cells. Stem cells can also be recovered from developing wisdom teeth and permanent teeth. However these teeth are less effective sources for stem cells than deciduous teeth. Therefore although individuals have different opportunities at different stages of their life to bank these valuable cells, it is best to recover stem cells when a child is young and healthy and the cells are strong and proliferative.

Researchers have found the pulp of exfoliated deciduous teeth to contain chondrocytes, osteoblasts, adipocytes, and mesenchymal stem cells.  All of these cell have great potential for the therapeutic treatment of:  Neuronal degenerative disorders such as Alzheimer’s, Parkinson’s, and ALS (Amyotrophic Lateral Sclerosis or Lou Gehrig’s Disease); chronic heart conditions such as congestive heart failure and chronic ischemic heart disease; periodontal disease  and to grow replacement teeth and bone.  One of the most important potential applications using these cells is for the treatment of paralysis due to spinal cord injury which has already been done using mesenchymal stem cells from other sources.

In theory, stem cells taken from the patient could be coaxed in the lab turning into a tooth bud which, when implanted in the gums, will give rise to a new tooth, and would be expected to be grown in a time over three weeks. It will fuse with the jawbone and release chemicals that encourage nerves and blood vessels to connect with it. The process is similar to what happens when humans grow their original adult teeth. Many challenges remain, however, before stem cells could be a choice for the replacement of missing teeth in the future.

Not all deciduous teeth are suitable for harvesting of stem cells. Teeth that become very mobile, either through trauma or disease, often have an inadequate blood supply, and are not candidates for stem cell recovery. This is why recovery of stem cells from primary teeth is preferred after an extraction rather than from a tooth that is so mobile it is ‘hanging on by a thread’.

Pulpal stem cells should not be harvested from teeth that exhibit any form of disease.

Not all teeth hold the same potential either. Deciduous incisors and canines with no pathology and at least one third of root left contain these unique types of cells in sufficient number. Primary molars are generally not considered for sampling unless they have been extracted early (for orthodontic purposes, for example).

The process for tooth collection, isolation and storage can be summarised  as follows:

If a healthy deciduous tooth is shed or otherwise lost and exhibits a red pulp (indicating it had been receiving blood until its loss) it should be placed in sterile saline solution. The childs parent should then call a tooth bank or the attending dentist of the bank.

In the event of a scheduled procedure, the dentist visually inspects the freshly-extracted tooth to confirm the presence of healthy pulpal tissue and the tooth or teeth is transferred into a vial containing a hypotonic phosphate buffered saline solution. This provides nutrients and helps to prevent the tissue from drying out during transport .The vial is then carefully sealed and placed into a thermette (a temperature phase change carrier) after which the carrier is then placed into an insulated metal transport vessel. The thermette along with the insulated transport vessel maintains the sample in a hypothermic state during transportation. This procedure is described as Sustentation.

The viability of the stem cells is both time and temperature sensitive. The time from harvesting to arrival at the processing storage facility should not exceed 40 hours.

Upon arrival at the tooth bank the tooth/teeth are subjected to a series of procedures after which viability of the sample (or otherwise) can be confirmed to the parent.

To date, tooth banking is not very popular but the trend is increasing with tooth banks already operating in  countries such as the USA, UK, Japan, Norway and others planned in Russia, Australia, India and the Middle East.

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