**Cryopreserved Musculoskeletal Tissue Bank in Dentistry: State of the Art and Perspectives**

1Luiz Augusto U. Santos1, Alberto T. Croci2, Nilson Roberto Armentano3, Zeffer Gueno de Oliveira4, Arlete M.M. Giovani5, Ana Cristina Ferreira Bassit6, Graziela Guidoni Maragni7, Thais Queiróz Santolin7 and Lucas da Silva C. Pereira8

#### **1. Introduction**

36 Current Frontiers in Cryopreservation

Foreskin Fibroblasts. *Advanced Science Letters*, Vol.3, No. 4, (December 2010), pp.

Maxillary and mandibular bone loss has long been a challenge to dental surgeons who seek to reconstruct these lost segments. These lesions lead to deformation of some maxillary and mandibular areas which interferes in the functional rehabilitation process of these structures. The most common cause of these lesions is prolonged use of total prostheses in a large part of the Brazilian population and the searches for surgical techniques and bone substitutes are today proposed and studied by the academic class. In this context, Brazil is starting to distribute allogeneic tissue obtained, processed and qualified by musculoskeletal tissue banks. Such banks already have experience in dispensing tissue to the orthopedic area, which has been using reconstructive techniques with allografts for many years. The first studies proposing the use of bone substitutes for replacement of these faulty parts commenced in the decades subsequent to 1860. (Carrel, 1912;Groves, 1917; Sharrard, Collins, 1961; Urist, 1965; Fischer, 1998; Tomford, 2000).

After the verification of the disadvantages in the use of autologous tissues for this purpose, such as the increase in donor morbidity, greater risk of nerve lesion and of infection inherent to the second surgical procedure and limitation in the availability of the tissue in quantity and variety, the use of homologous tissue became another option that was gradually indicated (Cunningham, Reddi, 1992; Tomford, 2000).

*<sup>1</sup>Institute of Orthopedics and Traumatology, Hospital das Clínicas of the School of Medicine of the University of Sao Paulo, dentist, Tissue Bank Technical Responsible and. Sao Paulo/SP, Brazil* 

*<sup>2</sup>Institute of Orthopedics and Traumatology, Hospital das Clínicas of the University of São Paulo school of Medicine, Professor and Tissue Bank Director - Sao Paulo/SP, Brazil* 

*<sup>3</sup>School of Dentistry of the University of Santo Amaro- São Paulo, Brazil* 

*<sup>4</sup>Orthopedic Nurse Specialist. São Paulo/SP, Brazil 5Nurse, Institute of Orthopedics and Traumatology, Hospital das Clínicas of the University of São Paulo school of Medicine, Tissue Bank Coordinator - São Paulo/SP, Brazil* 

*<sup>6</sup>Veterinarian, Tissue Bank Researcher, University of Florida, Gainesville, FL – Flórida- US* 

*<sup>7</sup>Nurse, Institute of Orthopedics and Traumatology, Hospital das Clínicas of the University of São Paulo school of Medicine, Tissue Bank Team - São Paulo/SP, Brazil* 

*<sup>8</sup> Dental Student, Institute of Orthopedics and Traumatology, Hospital das Clínicas of the University of São Paulo school of Medicine, Tissue Bank Team - São Paulo/SP, Brazil*<sup>1</sup>

Cryopreserved Musculoskeletal Tissue Bank in Dentistry: State of the Art and Perspectives 39

The osteoblasts are cuboid, elongated cells of mesenchymal origin that are located in the bone margins; their function is to produce the organic matrix of the bone tissue. In reduced activity these cells assume a more slender shape. The osteocytes are encapsulated osteoblasts, which after maturation became imprisoned inside the mineralized matrix, but that still maintain contact with other cells through cytoplasmic ramifications, thus maintaining physiologic functionality of the tissue (Junqueira, Carneiro, 1999; Davies 2000). This contact with surface cells such as the osteoblasts and lining cells is related bone structure maintenance and to the physiological responses that lead to tissue formation or

The osteoclasts are giant cells with multiple nuclei and their function is related to resorption.

The interaction and the synergism among bone cells is called creeping substitution, and this occurs through three essential cellular events*:* osteogenesis (cellular event that favors the synthesis of bone matrix by the osteoblasts), osteoinduction (ability to induce the migration of mesenchymal cells and their differentiation into osteoblasts) and osteoconduction (ability of the tissue to serve as a mold or guide for the cellular processes involved in bone tissue

Moreover, as is the case with others, the bone cells pass through the stages of the cell cycle, which range from formation to cell division (mitosis). Mitosis is susceptible to external interferences, and the cell can either enter a state of rest or continue to split cyclically (Urist,

The term transplant is not widely used by the dental community to refer to the use of bone tissue. The common term is bone grafting. The bone graft can receive a nomenclature and be

Autologous graft or autograft Graft of tissue from one site to another in the same

Allograft or homologous graft Graft between individuals of the same species with

The use of bone tissue for replacement of bone losses is not a recent procedure. Since last century there have been accounts of the use of these tissues in humans and in experiments

Xenograft or heterologous graft Graft from one individual of a species onto a

Table 1. Classification of grafts according to their nature. Source: Drumond, 2000

**4. Clinical application of grafts over the years** 

with animals as a means of assessing their efficacy.

Isograft Graft between people with the same genotype

individual

(homozygotes; e.g. identical twins)

disparate genotype

different species

classified according to the origin of its obtainment and on the implant site (Table 1).

1965; Enneking et al., 1975; Junqueira, Carneiro, 1999; Perren, Claes, 2002).

In synergy with the osteoblasts they promote bone remodeling.

The cells belonging to the bone tissue are the osteoblasts, osteocytes and osteoclasts.

resorption (Aubin et al., 2006).

**3. Bone transplantation** 

repair).

The good results with the clinical application of allografts in dentistry motivate their use on an increasing scale, until in 2005 Dentistry came into the scene with the use of tissues in maxillary and mandibular pre-prosthetic surgery. A consensus between the National Transplant System and the Federal Board of Dentistry allows the use of allografts by specialists in the areas of Implant Dentistry, Periodontics and Oral and Maxillofacial. The tissue banks, in turn, prepare a tissue processing line geared toward dental needs with a focus on quality control and traceability.

Thus usage has become both abrupt and a tendency in the last 5 years (RBT, 2006-2010). In spite of a significant number of bone transplants in the dental area with good clinical results, the dental profession is still lacking information about activities that involve the area of tissue banks, particularly in the rigid quality control and traceability. Such activities are founded on international standards2, literature3 and legislation4 and implemented according to Good Manufacturing Practice- GMP.

We consider it very important to gather epidemiological data on bone transplants in dentistry, elucidating the size and the limits of this type of treatment that is already considered a tendency in our field. In addition, to report on our perspectives of investigation into the efficacy and safety of the use of allografts, with tests that can enable us to expand our knowledge about the osseointegration of allografts. In other words, knowledge that allows us to reach what we consider most important in dental treatments: the predictability of treatment.
