Abstract: Milk tooth- a temporary tooth – it’s going to fall’ –a common notion routinely uttered by parent, even by medical and dental fraternity. In reality deciduous tooth has immense potential at present and in the coming future. The present review is aimed to discuss about the importance of deciduous tooth in the general wellbeing of a child and the adult in to which he will eventually grow. The role of human exfoliated deciduous tooth in the ongoing researches on stem cell therapy, biologic tooth, biologic restoration and over retained deciduous tooth has also been elaborated in the present topic.
“The childhood shows the man, as morning shows the day”- John Milton The term deciduous means literally 'to fall off’. Although the deciduous teeth are in time replaced by the succedaneous teeth, the deciduous teeth play a very important role during their time period in the proper alignment, spacing, and occlusion of the permanent teeth. It is what the child chews, speaks, and smiles with during child’s formative years. The deciduous teeth, the ‘Milk Teeth’ are also potentiate to make a light on the future of a human being who has shed those teeth on the course of life. The modern research on stem cell therapy derived from exfoliated deciduous teeth, biologic tooth and biologic restoration using exfoliated deciduous teeth has opened a new horizon on modern dental practice.
In the current review we are going to discuss about the ‘Present and Future of milk tooth’. In the review we are aimed to remind the dental professionals and thereby parents of child patients about the importance of milk tooth in their usual time period in mouth and also in future when they may be exfoliated or be over retained. Milk teeth are going to fall, so extract them when destructed, this common notion is to be corrected and this review is to throw light in this regard.
Present of milk Tooth:
Milk teeth i.e. deciduous teeth are the dentition present in mouth from at about the age of 6-7 months to 12-13 years .By the time they serve a major role in child’s growth, day to day living and wellbeing. The purpose served by the dentition are-(a)Phonation;(b)Mastication;(c)Assistance in proper development of jaw bone and masticatory musculature;(d)Maintenance of arch length;(e)Acceptable esthetics;(f)Maintenance of space for next permanent successors;(g)Maintenance of good healthy painless environment for permanent successors.
Future of Milk Tooth:
The future of milk teeth lies in four modalities of research and treatment options. These are- I.Stem cell therapy using deciduous teeth: Stem cell research are ongoing on followings- A. Stem cells from human exfoliated deciduous teeth (SHED)1 - (I)Exfoliated human deciduous tooth contains multipotent stem cells [stem cells from human exfoliated deciduous teeth (SHED)]. SHED were identified to be a population of highly proliferative, clonogenic cells capable of differentiating into a variety of cell types including neural cells, adipocytes, and odontoblasts. It was described by Masako Miura et al, 2003. After in vivo transplantation, SHED was found to be able to induce bone formation, generate dentin, and survive in mouse brain along with expression of neural markers. (II)Normal exfoliated human deciduous incisors were collected, the pulp was separated from a remnant crown and then digested in a specialized solution. Single-cell suspensions were cultured in a regular medium. These techniques resulted in a population that we have termed SHED. SHED were transplanted sub cutaneously into immunocompromised mice. Ex vivo-expanded SHED were infused to the dentate gyrus of the hippocampus. (III) When ex vivo-expanded SHED were transplanted into immunocompromised mice and the transplants yielded human-specific odontoblasts directly associated with a dentin-like structure. (IV)All transplanted SHED were capable of inducing bone formation in immunocompromised mice. (V) It was found that cultured SHED expressed a variety of neural cell markers. (VI) Cultured SHED was found to possess the potential to develop into lipid-laden fat cells.
(Fig 1-Transplanted SHED into immunocompromised mice1 )
B. MBP-SHED ( Mesenchymal Bone Producing cells derived from Stem cell from Human Exfoliated Deciduous teeth) capable of produce LAB (Living Autologous Bone)2- (I)A new subpopulation of stem cells derived from dental pulp, whose differentiation in osteoblasts lead to the subsequent production of a bone tissue, called LAB (Living Autologous Bone)described by Francesco Carinci et al,2004.The use of this cell population is to produce autologous bone tissue in vitro. This LAB can be used in donor patients to reconstruct bone tissue, as required in the daily practice in dentistry, maxillo-facial surgery and orthopedics. (II)The pulp of deciduous tooth is placed in a test-tube with specialized solution. The digested mixture has been diluted with culture medium and centrifuged. (III)The filtered solution was placed in a flask and put in an incubator .Cells were made to proliferate in the flask after 15 days. (IV) After several passages, a living autologous woven bone colonized from osteoblasts (LAB) has been obtained.
II.Biologic tooth3 : (I) It is a part of dental tissue engineering which encompasses the formation of either whole tooth or specific dental tissue from adult stem cells collected from deciduous teeth. (II) There are basically four ways to make a Biotooth. They are- (a) Stimulation of third dentition (tertiary tooth) presented as successional tooth formation to induce de novo tooth initiation in the adult mouth following permanent tooth loss (Otto et al. 1997). (b) Construction of an adult tooth de novo ,the idea that a complete adult tooth might be constructed .In this approach the constituent parts of a tooth are proposed to be made individually (Robey, 2005). (c)Scaffolds in the shape of different teeth are seeded with cells dissociated from early-stage third molar tooth germs and were grown in the omentum of immune compromised rats, and revealed the formation of tiny (1–2 mm) tooth crowns ,after20–30 weeks (Young et al. 2002).
(Fig 2-Biologic Tooth.3 )
III. Biologic Restoration4: (I) Early childhood caries results in severely mutilated deciduous anterior teeth and for their treatment, intracanal posts and crowns are mandatory in terms of esthetics. A Biological Restoration meets up to the esthetic and structural standards of natural teeth. Biologic restoration provide natural post and crown which can fit into the treated root stumps and replace the crown portion of tooth esthetically. (II) On the carious affected anterior teeth, pulpectomy done and the root canals are obturated leaving the coronal one third open. (III) The selected samples of deciduous teeth are procured from tooth tissue bank. (IV) Then the teeth are reshaped for preparation of crown preparation and the roots are shaped to function as posts. (V)The apical third of the roots are removed and the remaining root stumps are filled retrograde with flowable composite. (VI) Finally prepared crown and root are cemented with dual cure resin modified GIC. Excess material is removed and finishing & polishing is done.
(Fig 3-preperation of natural post4)
(Fig 4- retrograde filling of with flowable composite.4)
(Fig 5 -pre operative picture.4)
( Fig 6-post operative picture with biologic restoration4)
IV. Over-retained Deciduous tooth5: (I) Retention of deciduous tooth beyond their expected exfoliation date is called over retained deciduous tooth. (II)Assessment- Careful assessment is essential for all patients with retained deciduous teeth.Clinically this should focus on the coronal shape, color and structural integrity of the deciduous teeth. The gingival level of these teeth and their relationship to the occlusal plane should be noted .The structure of adjacent teeth that may serve as possible bridge abutments should be assessed clinically as should the alveolar bone volume. (III)Treatment Options: Retain – if the root and coronal structure are good, the tooth is functionally and aesthetically acceptable, a deciduous tooth may be retained intact. Retain and modify – Where root and crown structure are good but infra-occlusion has occurred or aesthetic improvement is required, the deciduous tooth may be retained and reshaped.
(Fig 7-over retained max laterals & canines5)
( Fig 8-retained with direct composite restoration5)
(Fig 9-over retained first molars5)
(Fig 10- retained with fixed prosthesis5)
(Fig 11-over retained second molar5)
(Fig 12-retained with indirect composite restoration5)
Extraction and space closure– where crowding exists and an extraction is necessary in order to align the arch orthodontically, it is usually common to extract the retained deciduous teeth. Extraction and prosthetic replacement– if the arch is well aligned but the prognosis of the deciduous tooth is poor due to root resorption, caries, periodontal or periapical disease, extraction and prosthetic replacement may be necessary.
Days have come when the Tooth Fairy and the Scientist are going to fight for exfoliated milk tooth because of its immense potential in, stem cell research, research on biologic tooth, preservation of retained deciduous tooth and biologic restoration. So, milk tooth which is so important for future generation should be given proper importance at present by maintaining good oral hygiene of child. References:
(1)Masako Miura ,Stan Gronthos ,Mingrui Zhao ,Bai Lu ,Larry W. Fsiher, Pamela Gehron Robey and Songtao Shi: SHED: Stem cells from human exfoliated deciduous teeth. Proceedings of the National Academy of Sciences of the United States of America, PNAS May 13, 2003 vol. 100 no. 10 5807-5812. (2)Francesco Carinci, Riccardo D'Aquino, Alfredo De Rosa ,Antonio Graziano, Gianpaolo Papaccio: Stem cells obtained from pulp of deciduous or permanent teeth and of dental germ, able to produce human bone tissue. PRINCETON, NJ US, IPC8 Class: AA61K914FI, USPC Class: 424484. (3)Rachel Sartaj and Paul Sharpe: Biological tooth replacement. J Anat. 2006 October; 209(4): 503–509. (4)Grewal N, Reeshu S: Case Report-Biological Restoration: An Alternative Esthetic Treatment For Restoration Of Severely Mutilated Primary Anterior Teeth .Jaypee’s International Journal of Clinical Pediatric Dentistry ,September-December 2008;1(1):42-47. (5)S. Robinson and M. F. W-Y. Chan: New teeth from old treatment options for retained primary teeth.British Dental Journal 2009; 207: 315–320. (6)Sobha Tandon: Textbook of Pedodontics, 2nd edition, Paras Publication. (7)SG Damle: Textbook of Pediatric dentistry, 3rd edition, Arya Publication. (8)Ash & Nelson: Wheeler’s Dental Anatomy, Physiology and Occlusion, 8th edition, Elsevier.