**13. Homologous tissue transplants in dentistry**

Dentistry has also sought biomaterials usable in the replacement of mandibular and maxillary bone loss over the years. The transplantation of bone portions taken from the iliac crest and menton (autologous transplant) has been broadcast in recent years, yet similarly to what happened in the orthopedic area, the disadvantages related to donor morbidity and the good results observed in the use of allografts in orthopedic patients, motivated professionals and patients to adopt this form of treatment.

In Brazil the use of bone transplants in dentistry started in 2005 after a consensus regarding the need for use and administrative mobilizations with the National Transplant System, Federal Council of Dentistry and Musculoskeletal Tissue Banks. This consensus serves as a starting point for the definition of criteria for requests for these tissues at the existing banks, where the professional must be a specialist in the areas of Implant Dentistry, Periodontics or Oral and Maxillofacial.

Rules related to logistics and traceability were incorporated into the activities of existing tissue banks, which then started to implement the bone tissue processing and distribution programs for dental purposes. In this program it is crucial to record the entire process with a focus on health control, including adverse deeds and traceability from the request to the actual transplantation. Specific forms are used for this purpose, including the Request Form, Terminated Transplantation Form, Non-Conformity Term and Adverse Effect Form.

Once standardized, this type of transplant is initiated in the country with widespread adoption by dentists, as observed in the Brazilian transplantation records. (RBT, 2006-2010)

Naturally, the Maxilla and Mandible are today the main bone tissue receptor areas in dentistry that have very distinctive characteristics when submitted to the osteolysis processes, which, in turn, require distinctive techniques during the bone transplant. The size and shape of the bones are influenced by several factors, which range from the genetic conditions of the individual to the environment in which they live. In other words, age, sex, physical characteristics, health, diet, race and place of residence are aspects to be considered (Moore, 1990).

Maxillary and Mandibular development and growth are determined by the appearance of teeth from the first months of life. It is interesting to note that the mandibular and maxillary bone tissue responds to intrinsic and extrinsic factors throughout the lifetime of an individual, and, therefore is very plastic, which counteracts its rigid and inert appearance.


Dentistry has also sought biomaterials usable in the replacement of mandibular and maxillary bone loss over the years. The transplantation of bone portions taken from the iliac crest and menton (autologous transplant) has been broadcast in recent years, yet similarly to what happened in the orthopedic area, the disadvantages related to donor morbidity and the good results observed in the use of allografts in orthopedic patients, motivated

In Brazil the use of bone transplants in dentistry started in 2005 after a consensus regarding the need for use and administrative mobilizations with the National Transplant System, Federal Council of Dentistry and Musculoskeletal Tissue Banks. This consensus serves as a starting point for the definition of criteria for requests for these tissues at the existing banks, where the professional must be a specialist in the areas of Implant Dentistry, Periodontics or

Rules related to logistics and traceability were incorporated into the activities of existing tissue banks, which then started to implement the bone tissue processing and distribution programs for dental purposes. In this program it is crucial to record the entire process with a focus on health control, including adverse deeds and traceability from the request to the actual transplantation. Specific forms are used for this purpose, including the Request Form,

Once standardized, this type of transplant is initiated in the country with widespread adoption by dentists, as observed in the Brazilian transplantation records. (RBT, 2006-2010) Naturally, the Maxilla and Mandible are today the main bone tissue receptor areas in dentistry that have very distinctive characteristics when submitted to the osteolysis processes, which, in turn, require distinctive techniques during the bone transplant. The size and shape of the bones are influenced by several factors, which range from the genetic conditions of the individual to the environment in which they live. In other words, age, sex, physical characteristics, health, diet, race and place of residence are aspects to be considered

Maxillary and Mandibular development and growth are determined by the appearance of teeth from the first months of life. It is interesting to note that the mandibular and maxillary bone tissue responds to intrinsic and extrinsic factors throughout the lifetime of an individual, and, therefore is very plastic, which counteracts its rigid and inert appearance.

*Pathophysiology of Bone Loss*

Functional (force applied to edge (pressure, compression, tension,

Terminated Transplantation Form, Non-Conformity Term and Adverse Effect Form.

**13. Homologous tissue transplants in dentistry** 

professionals and patients to adopt this form of treatment.

Oral and Maxillofacial.

(Moore, 1990).

**Metabolic Factors***:*  Age; Gender;

*Mechanical Factors:*

 Hormone balance; Osteoporosis;

shearing)):

Nutritional disorders.


Table 2. Factors related to the bone loss process (Source: Fonseca & Davis, 1995)

One of the factors most closely related to the indication of bone reconstructions in dentistry are maxillary and mandibular resorptions due to lack of the dental element.

The resorption of the alveolar edge is a chronic, progressive, irreversible and cumulative alteration. This condition, observed in the toothless individual, becomes faster in the first six months after exodontias or dental extractions. Once the function of providing support to the teeth has been lost, the alveolar process tends to undergo resorption due to disuse (Mecall & Rosenfeld, 1991). And this resorption can be exacerbated by local factors (traumatism, infections and pathologies), systemic factors (osteopenia, osteoporosis, osteomalacia, endocrine and nutritional alterations), systemic health problems, prosthetic treatments and others (Fonseca & Davis, 1995; Gassen et al, 2008)

Projections by the Brazilian Institute of Geography and Statistics (IBGE) show that the elderly population in Brazil is set to increase considerably in future years. Life expectancy in 2020 is estimated at 71.2 years (men) and 74.7 years (women) and will represent 13% of the population (IBGE, 2011). Data from the Epidemiological Survey indicate the elderly age bracket as having the highest rates of edentulism and of prosthesis use for prolonged periods. (Ministério da Saúde, 2003)

The previous use not only of total prostheses but also of removable partial prostheses is identified as a predisposing factor of tissue resorption (odds ratio = 2.4), and the flaccid tissue from the edge is related to the severity of resorption (odds ratio = 2.4). (Watzek, 1996, Xie et al, 1997)

In this context, it is noted that the majority of atrophic edentulous cases (total or partial) has increasingly resorted to the adoption of dental implants and for this reason, bone grafts appear as an option of biomaterial used in pre-prosthetic surgery (Galea, 2005).

Frozen homologous bone tissue is biocompatible and can be used successfully in treatments that require maxillary sinus lifting. Its use favors bone neoformation, integration, and absence of inflammatory infiltrate as well as an increase in the percentage of bone volume (Stacchi et al, 2008). In the long term, it is possible to observe the formation of viable and mature bone tissue, providing adequate reconstruction techniques are adopted. (Contar et al, 2009)

Some studies in the dental area have evaluated the efficacy of the use of allografts through an analysis of the biomechanics of implants placed in the grafting zone. This is possible through a resonance frequency analysis (RFA) and removal torque (RT) analysis. The results show that there is no difference in stability between implants installed with autogenous and allogeneic grafts. (Ribeiro, 2009) It is also possible to evaluate the osseointegration process through an evaluation of the neoformed bone volume. Lima (2010) studied homologous

Cryopreserved Musculoskeletal Tissue Bank in Dentistry: State of the Art and Perspectives 59

Bone Volume (**BV/TV** %): percentage of bone tissue formed by mineralized or

Thickness of the woven bone (**Tb.Th** m): thickness of the bone trabeculae expressed in

Trabecular number (**Tb.N**/mm): the number of bone trabeculae, by millimeter of tissue,

Trabecular separation (**Tb.Sp** m): the distance between the bone trabeculae expressed

Number of osteocytes (**N.Ot**): number of osteocytes present in the area of the bone

Illustration 14. Equipment used for histomorphometric analysis (microscope coupled to

Osteoid volume (**OV/BV** %): percentage of osteoid matrix in relation to the trabecular

 Osteoid surface (**OS/BS** %): percentage of trabecular surface covered by osteoid matrix; Osteoblast surface (**Ob.S/BS** %): percentage of the trabecular surface that presents

Osteoid thickness (**O.Th** m): the thickness of the osteoid matrix deposited on the bone

digitizing board and Osteomeasure® software)

trabeculae, expressed in micra;

FORMATION PARAMETER

bone;

osteoblasts;

which is also an index that expresses trabecular density;

unmineralized trabecular bone;

micra;

in micra;

tissue evaluated.

bone grafts processed in a tissue bank with different methods (lyophilized, demineralized and radiated (ALD); mineralized frozen (ACM) besides autogenous grafts (AT) and blood clot (CG). In the Guided Bone Regeneration (GBR) technique, samples of the groups of grafts were placed in 32 cylinders fastened to the calvaria of 08 animals. After 13 weeks the cylinder fill rates (bone volume of the ALD group) were similar to the ACM and superior to the autogenous graft). Bone neoformation also occurs during the use of homologous grafts in maxillary sinus lifting surgery, besides affording lower morbidity levels (Viscioni et al, 2010). Hence it should be considered a valid alternative for the replacement of autologous grafts in patients submitted to implant therapy.
