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 Table of Contents  
REVIEW ARTICLE
Year : 2014  |  Volume : 5  |  Issue : 3  |  Page : 190-194

The role of stem cells in dentistry: Biological solutions to biological problems


1 Department of Oral and Maxillofacial Surgery, Saraswati Medical and Dental College, Lucknow, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, Saraswati Medical and Dental College, Lucknow, Uttar Pradesh, India

Date of Web Publication14-Aug-2014

Correspondence Address:
Rakhi Issrani
Department of Oral Medicine and Radiology, Saraswati Medical and Dental College, 233, Tiwariganj, Faizabad Road, Lucknow - 227 105, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-433X.138749

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  Abstract 

Advances in the field of dentistry in the last millennium and in the present decade have brought about revolutionary changes in the way we understand and treat diseases. The stem cells are one of the most favorable areas of biology. The breakthrough in stem cell research holds significant promise for clinical application in human patients to regenerate human cells, which are damaged due to illness, developmental defects, and accidents. This article takes you on a sojourn of the stem cells, their characteristics, sources, their potential applications and possible barriers of its application along with the overview of where dentistry stands in this field.

Keywords: Adult stem cells, embryonic stem cells, mesenchymal stem cells, stem cells


How to cite this article:
Prabhu N, Issrani R. The role of stem cells in dentistry: Biological solutions to biological problems. SRM J Res Dent Sci 2014;5:190-4

How to cite this URL:
Prabhu N, Issrani R. The role of stem cells in dentistry: Biological solutions to biological problems. SRM J Res Dent Sci [serial online] 2014 [cited 2022 May 16];5:190-4. Available from: https://www.srmjrds.in/text.asp?2014/5/3/190/138749


  Introduction Top

"Deep in the cavern of the infant's breast,

The father's nature lurks, and lives anew!!!"

-Horace

The sojourn of science has understood that the secret of life lies in the "DNA," thanks to Sir James Watson and Crick for their epoch making a historic discovery. The scientific discoveries in cellular, developmental and molecular biology have truly revolutionized our collective understanding of the biological processes that could greatly impact and dramatically change our lives in the future. [1] Stem cells are one of the most favorable areas of molecular biology. Judging from the explosion of articles not only in scientific journals, but also in the mass media and on the internet, one could say that the stem cells are likely to revolutionize the entire health care delivery.

Although the regeneration of a lost tissue is known to mankind for several years, it is only in the recent past that research on stem cells in dentistry has gained momentum and is likely to result in a paradigm shift in the therapeutic armamentarium of dental diseases. [1] Discovery that human mature pulp tissue contains a population of multipotent mesenchymal dental pulp stem cells with high proliferative potential for self-renewal and the ability to differentiate into functional odontoblast has revolutionized dental research and opened new avenues in particular for reparative and reconstructive dentistry and tissue engineering in general. [2] Dental precursor cells are attractive for novel approaches to treat diseases like periodontitis, dental caries or to improve dental pulp healing and the regeneration of craniofacial bone and teeth. These cells are easily accessible and in contrast to bone-marrow-derived, mesenchymal stem cells (MSCs) are more closely related to dental tissues. [3]

This article takes you on a sojourn of the stem cells, their characteristics, sources, their potential applications and possible barriers of its application along with the overview of where does dentistry stand in this field.


  Stem cells and their sources Top


The term stem cell was proposed for scientific use by Russian histologist Alexander Maksimov in 1908. While research on stem cells grew out of findings by Canadian scientists in the 1960s. [2] Stem cells are unspecialized and pluripotent cells with an extraordinary ability to self-renew, capable of differentiating into one or more specialized cell types playing a crucial role in homeostasis and tissue repair. A particular cellular developmental pathway of stem cells consists of: [1]

Stem cell → stem cell + progenitor cell → differentiated cell.

There are two basic categories of stem cells classified according to their potential of differentiation: embryonic stem cells (ESC) and adult stem cells ([ASC] or MSCs). While the use of ESC is limited by ethical issues, ASC constitute a more favorable cellular source to be used in tissue engineering. It has been isolated from several tissues including brain, skin, hair follicles, skeletal muscle, bone-marrow and dental tissues.

The various types of stem cells and their differentiation in formation of different cell lines [4] are shown in [Table 1].
Table 1: Types of stem cells

Click here to view


Dental stem cells

The search for more accessible MSC than those found in bone-marrow has propelled interest in dental tissues. Five types of dental MSC are isolated with the following characteristics: [5]

  1. Dental pulp stem cells from pulp of permanent teeth especially from third molars;
  2. Stem cells of human exfoliated teeth and immature dental stem cells from primary teeth;
  3. Periodontal ligament stem cells;
  4. Stem cells from apical papilla; and
  5. Dental follicle progenitor cells.


The dental-tissue-derived stem cells are isolated from specialized tissue with potent capacities to differentiate into odontogenic cells. However, they also have the ability to give rise to other cell lineages such as osteogenic, chondrogenic, adipogenic, myogenic, and neurogenic cells. [6]

The properties of different types of dental stem cells [7] are summarized in [Table 2].
Table 2: Summary of dental stem cell properties

Click here to view



  Need for stem cell research Top


Advances in stem cell research have explored many therapeutic avenues and the insight gained by a pilot proof of concept studies promises a plethora of unimaginable benefits: (1)

  1. They are useful in functional genomics study to understand human embryonic gene expression, genomic data mining, and bioinformatics.
  2. They serve to study biological processes which help in understanding human developmental disorders like birth defects, cancers, etc.
  3. They are new means of creating human disease models for drug discovery and development. It serves as an alternative to animal toxicology thereby hastening the drug to the market.



  Dental stem cell researc Top


This is an exciting time for the dental professionals. Stem cells and stem cell therapies will emerge to become an important aspect in the everyday practice of dental professionals. We will continue to see the advancement of dental stem cell research and dental stem cells applied to clinical therapies. Regenerating the pulp of a tooth is right around the corner, and it will broaden the horizon for dentists and their patients within the next few years. On a global scale, there is a tremendous investment from both the public and private sectors in stem cell research. Dental Institutes should add stem cells and regenerative therapies to the curriculum as a dentist will play an important role in raising patient awareness of regenerative medicine, stem cells, stem cell research and the benefits of stem cell banking for use in future regenerative therapies. It is of utmost importance that the patients of the future, value in preserving teeth that will be exfoliated or extracted as the MSCs in teeth are the easiest to retrieve and preserve and are typically removed and thrown out as medical waste. If they are saved, they could be used in the future to save many lives and remove the problem of waiting for transplants, which so many people face today. Hence, banking dental stem cells is like a form of bio insurance-saving them now is an easy, affordable and noninvasive strategy to ensure their availability in the future when they will be needed the most in the field of regenerative dentistry and medicine.


  Potential applications of stem cells in medicine Top


Applications of regenerative medicine technology may offer new therapies for patients with chronic debilitating diseases. Currently, patients with injuries, end-stage organ failure, or other clinical problems can be treated with transplanted organs. However, there is a shortage of donor organs that is worsening yearly as the population ages and new cases of organ failure increase. Scientists in the field of regenerative medicine and tissue engineering are now applying the principles of cell transplantation, material science, and bioengineering to construct biological substitutes that will restore and maintain normal function in diseased and injured tissues. The stem cell field is a rapidly advancing aspect of regenerative medicine as well, and new discoveries here create new options for this type of therapy. Stem cell-based therapies are being investigated for the treatment of many conditions, including neurodegenerative conditions such as Parkinson's disease and multiple sclerosis, liver disease, diabetes, cardiovascular disease, autoimmune diseases, musculoskeletal disorders, and for nerve regeneration following brain or spinal cord injury. [1]

The MSCs found in teeth may be beneficial for the treatment of neurodegenerative diseases and repair of motor nerves following stroke or injury. This exciting research will lead to future treatment options that allow muscles to repair themselves following injury, such as the muscle damage that occurs after a heart attack, or the structural damage that occurs following a knee injury. Human stem cells could also be used to test new drugs. For example, new medications could be tested for safety on differentiated cells generated from human pluripotent cell lines. Cancer cell lines, for example, are used to screen potential anticancerous drugs.


  Current scope of applications of stem cells in dentistry Top


Tooth loss compromises human oral health. Although several prosthetic methods, such as artificial denture and dental implants, are clinical therapies to tooth loss problems, they are thought to have safety and usage time issues. Stem cell-based tissue engineering is thought to be a promising way to replace the missing tooth. [8] Years from now dental stem cells will hopefully be able to correct cleft palate sparing children from multiple surgeries; stem cells will also have the potential to save injured teeth and jaw bones, correct periodontal defects, and most strikingly regenerating entire tooth structures. The regenerative potential of ASCs obtained from various sources including dental tissues has been of interest for clinicians over the past years and most research is directed toward achieving the following: [1]

Regeneration and healing of damaged coronal dentin and pulp

To this date, no restorative material has been able to mimic all physical and mechanical properties of tooth tissue. If the regeneration of tooth tissue is possible in these situations, it facilitates physiologic dentin deposition that forms an integral part of the tooth thereby restoring structural integrity, minimizing interfacial failure, microleakage, and other consequent complications. Similarly, young permanent teeth that require apexogenesis or apexification are the perfect candidates for the regeneration of pulp as they allow completion of both vertical and lateral root development, improving the long-term prognosis.

Periodontal tissue regeneration

Regenerating the periodontium has always been a high priority in craniofacial regenerative biology. Due to the complex structure of the periodontium its complete regeneration has always remained a challenge. All the current regenerative techniques such as autologous bone grafts, allografts, or alloplastic materials have limitations and cannot be used in all clinical situations. Therefore, a cell-mediated bone regeneration technique will be a viable therapeutic alternative. The outstanding issue with these approaches is the extent to which any reconstituted periodontium can maintain the integrity and function during mastication over long periods of time. Current treatments for severe periodontitis are poor, however, and thus, despite their flaws, any new dental stem cell-based treatments are likely to be the subject of intensive clinical research in the near future.

Repair and replacement of bone in craniofacial defects

Craniofacial bone grafting procedures rely on autologous bone grafting, devitalized allogenic bone grafting, and natural/synthetic osteoconductive biomaterials. Autologous bone grafting is limited by donor site morbidity and allogenic bone is often destroyed soon. A long-term outcome using biomaterials relies on their ability to encourage local cells to completely regenerate a defect and results are often not encouraging. If stem cells can be harvested in a scaffold and transplanted into a defect to regenerate the lost tissue, it can alleviate a lot of complications associated with the traditional techniques.

Bio-root engineering

A therapeutic option that was unthinkable a few years ago seems an achievable goal today. Even to this day, the replacement of missing teeth has limitations. Although, dental implants are a significant improvement over dentures and bridges, their fundamental limitation is the lack of natural structural relationship with the alveolar bone. They rely on direct integration of bone on the tooth surface, which is indeed an unnatural relationship as compared with the natural tooth. Further, they are also associated with a lot of aesthetic, functional, and surgical limitations that affect their prognosis. The ultimate goal in dentistry is to have a method to biologically replace lost teeth; in essence, a cell-based implant rather than a metal one.

Scientifically, the regeneration of whole teeth de novo remains the most attractive challenge in dental tissue regeneration. Coaxing dental stem cells into initiating developmental cascades to form complex tooth organs with enamel, dentin, and roots would be both scientifically and clinically attractive. Stem cells are being applied to dental implants and they have been shown to form a ligamentous attachment between the implant and bone. So far, progress has been based on the ability of tooth germ-derived tissues to self-organize and reassemble into a developing tooth organ.

Temporomandibular joint (TMJ) regeneration

Tissue-engineered bone grafts will be useful for practitioners in all of the dental specialties. Future tissues may also include engineered TMJ joints and cranial sutures, which would be especially helpful to craniofacial and oral maxillofacial surgeons.

Repair of genetic oro-facial diseases/disorders

Most clinical therapies and treatments on disorders of neural, retinal, hepatic, bone and tissue aberrations are mostly focused on only particular tissue aspects of the human body. However, some of these disorders have oro-facial manifestations. Mutations have been shown to play a dominant part in most oro-facial diseases. One of the main focuses of the present stem cell therapy is genetic correction such as in patients suffering from sickle cell anemia, which would be a permanent solution. Another useful application is to study dental stem cells harvested from individuals exhibiting a variety of craniofacial skeletal and dental syndromes in order to increase our understanding of the molecular nature of diseases ranging from cleidocranial dysplasia syndrome and Treacher-Collins syndrome. In this way, targeted therapies may eventually be devised to treat and/or prevent some of these diseases. Considering the success of such attempts using tissue engineering techniques, more fruitful advantage can be expected for their use in cell transplantation therapies and gene corrections in oro-facial disorders.

Continued root formation

Research suggests that root apical papilla is likely to play a pivotal role in root formation, further research is needed to verify the role of stem cells from apical papilla in continued root formation. [9]

Other potential use of stem cells in dentistry

Other potential use of stem cells in dentistry includes regeneration of resorbed root, cervical or apical dentin, and repair perforations.


  Challenges in stem cell research Top


Despite some progress, there remain major obstacles to formulating safe, simple and reproducible cell-based approaches for tooth repair and regeneration that could be used on patients. Vast unequal resources, differential standards of public health, and uneven opportunities for health care within and between countries comprise a major hurdle in achieving substantial success in the field of genetics. Along with these, funding for the purpose of stem cell research should also be taken into account.


  Conclusion Top


Despite the significant advances made in dentistry over the years, replacing the experienced processes perfected by nature is indeed a difficult proposition. Although there is little doubt that the best material to replace a tooth or tooth-related tissue is the tooth tissue itself, the question that lies before us is "Can we do it in a way that is predictable and is it clinically feasible?" For any new therapy to be accepted, it should either be more effective than or as effective as the existing therapy with added advantages in terms of technique being simpler, more predictable, long-lasting, time/cost-effective, etc. If the above goal has to be achieved and if laboratory research has to be translated into clinical practice, there are certain barriers that have to be first understood and later overcome. Hence, stem cells offer exciting promise for future therapies, but significant technical hurdles remain that will only be overcome through years of intensive research.

 
  References Top

1.Nadig RR. Stem cell therapy - Hype or hope? A review. J Conserv Dent 2009;12:131-8.  Back to cited text no. 1
[PUBMED]  Medknow Journal  
2.Karien GA. Dental pulp stem cells - A new era in tissue engineering. Smile Dent J 2009;4:6-7.  Back to cited text no. 2
    
3.Morsczeck C, Schmalz G, Reichert TE, Völlner F, Galler K, Driemel O. Somatic stem cells for regenerative dentistry. Clin Oral Investig 2008;12:113-8.  Back to cited text no. 3
    
4.Mao JJ. Stem cells and the future of dental care. N Y State Dent J 2008;74:20-4.  Back to cited text no. 4
    
5.Volponi AA, Pang Y, Sharpe PT. Stem cell-based biological tooth repair and regeneration. Trends Cell Biol 2010;20:715-22.  Back to cited text no. 5
    
6.Huang GT, Gronthos S, Shi S. Mesenchymal stem cells derived from dental tissues vs. those from other sources: Their biology and role in regenerative medicine. J Dent Res 2009;88:792-806.  Back to cited text no. 6
    
7.Mohamed J, Sami C, Goodis H, Karam SM. Dental stem cells and their potential role in regenerative medicine. J Med Sci 2011;4:53-61.  Back to cited text no. 7
    
8.Peng L, Ye L, Zhou XD. Mesenchymal stem cells and tooth engineering. Int J Oral Sci 2009;1:6-12.  Back to cited text no. 8
    
9.Vyas S, Vyas K, Satish M, Shende V, Srivastav R. Stem cells - The future of dentistry - A review. J Indian Acad Oral Med Radiol 2011;23:S370-2.  Back to cited text no. 9
    



 
 
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Abstract
Introduction
Stem cells and t...
Need for stem ce...
Dental stem cell...
Potential applic...
Current scope of...
Challenges in st...
Conclusion
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