Journal of Dental Implants
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Table of Contents
REVIEW ARTICLE
Year : 2012  |  Volume : 2  |  Issue : 2  |  Page : 115-116

Tissue-engineered periodontal ligament on implants: Hype or a hope?


Department of Periodontics, Thai Moogambigai Dental College, Golden George Nagar, Chennai, Tamil Nadu, India

Date of Web Publication10-Oct-2012

Correspondence Address:
Lalitha Tanjore Arunachalam
Reader, No.6, Main Street, Dr. Tirumurthy Nagar, Nungambakkam, Chennai - 600 034, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-6781.102227

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   Abstract 

In the past decade, implants seem to be the mainstay of dentistry. The advent of periodontal tissue engineering has revolutionized not only periodontology but also implant dentistry at large. This brief report highlights on how the tissue engineered periodontal ligament on implants is going to change the traditional way of implant treatment.

Keywords: Implants, periodontal ligament, tissue engineering


How to cite this article:
Arunachalam LT, Sudhakar U, Merugu S, Janarthanan AS. Tissue-engineered periodontal ligament on implants: Hype or a hope?. J Dent Implant 2012;2:115-6

How to cite this URL:
Arunachalam LT, Sudhakar U, Merugu S, Janarthanan AS. Tissue-engineered periodontal ligament on implants: Hype or a hope?. J Dent Implant [serial online] 2012 [cited 2019 May 19];2:115-6. Available from: http://www.jdionline.org/text.asp?2012/2/2/115/102227


   Introduction Top


Implants and only implants seem to be the norm of the day. The boom in implant dentistry is attributed to a combination of various reasons; prolonged life span of aging individuals, failures associated with removable and fixed prostheses, advantages, and predictable outcomes associated with use of implants. Implants seem to be the obvious solution and titanium has been recognized as biocompatible alternative in replacing missing teeth. They are retained in the oral cavity by virtue of their direct structural and functional bond formation between bone and titanium, i.e., osseointegration, which is pivotal for clinical success. However, sometimes the absence of movement of the implant denture, can cause build up of forces and drastically harm the quality and quantity of the surrounding alveolar bone, implant as well as the TMJ. Over the years, many strategies have been explored to improve the osseointegrative property of the implant, be it the surface modifications to improve the mechanical, physical, and chemical characteristics of the implant, by modifying the shape and design, [1] altered surface topography to control cell behavior, [2] nanostructured surface coatings [3] or the addition of biomimetics (growth factors) to the implant surface. [4]

Though implants are an ideal way to replace a missing tooth, still lacking is the presence of the periodontal ligament, as in the natural teeth. This soft, richly vascular, and cellular connective tissue permits forces, elicited during masticatory function and other contact movements to be distributed to the alveolar process via the alveolar bone proper. It acts like a shock absorber, giving the tooth some movement in the socket. It also provides proprioception. The periodontal ligament also has an important interaction with the adjacent bone, playing the role of the periosteum, at the bone side facing the root. It homes vital cells such as osteoclasts, osteoblasts, fibroblasts, cementoblasts, cementoclasts, and most importantly, the undifferentiated mesenchymal stem cells. These cells are all important in the dynamic relationship between the tooth and the bone. Therefore, strategies to generate dental implants with associated periodontal tissues have become a new approach in tooth replacement therapies.

As early as 1990, Buser et al. [5] showed that titanium dental implants when placed in contact with retained root tips, the periodontal ligament of these roots served as a source for cells which could populate the implant surface during healing. Now, tissue engineering has opened a new vista in periodontal regeneration and more so in the treatment of dental implants. From various scaffolds to matrices, all have proved their ability to regenerate the entire periodontium. Lin et al. [6] reported the utilization of autologous rat PDL cells derived from molar tooth root surfaces to regenerate PDL tissues on titanium. They used Matrigel, a three-dimensional biomatrix scaffold rich in essential ECM components, to facilitate organized rat PDL regeneration at the titanium-implant-alveolarbone interface. Bioengineered cementum-like tissue was observed in 10% of the PDL-cell-seeded experimental implants, with associated collagen fibers oriented perpendicular to the implant surface. Cultured PDL cells exhibited high proliferation rates, clonogenicity, and formed cementum-like tissue on the titanium implant surface, and PDL tissue with Sharpey's fibers inserted perpendicular to the implant. In another study, Gault et al. [7] used ligaplants (combination of PDL cells with implant biomaterial) for tooth replacement. The study involved animal experiments on mice and canine models as well as human clinical investigation. In the canine model, PDL formation was observed and a new layer of tissue resembling repair cementum was formed on the ligaplant surface. In humans, after surgery, a desmodontal gap, corresponding to PDL space of normal width, was evident around one ligaplant, and the structure of lamina dura resembled that around a natural tooth. In one ligaplant, radiographs indicated that it had moved inside apparently intact bone, indicating the presence of newly formed periodontal ligament.

Therapeutic success can be achieved only when a high proportion of cultivated cells should organize into a new PDL. Few of the disadvantages of these cell-based tissue engineering is that, prolonged culturing is required to obtain a cushion of sufficient thickness and culturing for a long time leads to the appearance of non-PDL cell types. Now, cell sheet engineering is emerging as promising technology which can change the implant therapy as a whole. It involves covalent grafting of a temperature-responsive polymer Poly N-isopropylacrylamide (PIPAAm) surface without the use of scaffolds. [8] When the temperature is lowered to below 32 C, rapid hydration and swelling of the grafted PIPAAm occur, leading to the surfaces becoming hydrophilic. This causes cells to spontaneously detach without enzymatic dispersion treatments that might destroy critical cell surface proteins such as ion channels. Using cell sheet engineering methods, cells can be harvested as intact sheets along with their deposited ECM. Due to the presence of deposited ECM on the basal sheet surface, cell sheets harvested from temperature responsive culture surfaces can be directly attached to host tissue without the use of any mediators.

The surgical procedure for ligaplants seems to be easy as proposed by Gault et al. [7] because the implant is not tightly bound to the bone. These also have the added advantage of inducing new bone formation even when placed in sites associated with large periodontal defects, precluding the need for bone grafting also. In conclusion, evidence shows that implants with tissue-engineered ligament definitely score over the current implant scenario and are going to be the future in implant dentistry.

 
   References Top

1.Chen F, Terada K, Handa K. Anchorage effect of various shape palatal osseointegrated implants: A finite element study. Angle Orthod 2005;75:378-85.  Back to cited text no. 1
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2.Oates TW, Valderrama P, Bischof M, Nedir R, Jones A, Simpson J, et al. Enhanced implant stability with a chemically modified SLA surface: A randomized pilot study. Int J Oral Maxillofac Implants 2007;22:755-60.  Back to cited text no. 2
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3.Hedia HS. Effect of coating thickness and its material on the stress distribution for dental implants. J Med Eng Technol 2007;31:280-7.  Back to cited text no. 3
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4.Park JM, Koak JY, Jang JH, Han CH, Kim SK, Heo SJ. Osseointegration of anodized titanium implants coated with fibroblast growth factor-fibronectin (FGF-FN) fusion protein. Int J Oral Maxillofac Implants 2006;21:859-66.  Back to cited text no. 4
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5.Buser D, Warrer K, Karring T. Formation of a periodontal ligament around titanium implants. J Periodontol 1990;61:597-601.  Back to cited text no. 5
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6.Lin Y, Gallucci GO, Buser D, Bosshardt D, Belser UC, Yelick PC. Bioengineered periodontal tissue formed on titanium dental implants. J Dent Res 2011;90:251-6.  Back to cited text no. 6
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7.Gault P, Black A, Romette JL, Fuente F, Schroeder K, Thillou F, et al. Tissue-engineered ligament: Implant constructs for tooth replacement. J Clin Periodontol 2010;37:750-8.  Back to cited text no. 7
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8.Okano T, Yamada N, Sakai H, Sakurai Y. A novel recovery system or cultured cells using plasma-treated polystyrene dishes grafted with poly (N-isopropylacrylamide). J Biomed Mater Res 1993;27:1243-51.  Back to cited text no. 8
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