RESUMO
It has been related in orthopedic surgeries the HLA sensitization. Thus, we evaluate if the use of fresh-frozen homologous bone (FFHB) for dental implant placement induce anti-HLA sensitization. Six patients were treated with FFHB corticocancellous block grafts. After 6 months, bone biopsies were harvested during implant placement to allow histomorphometric analysis. Vital mineralized tissue (VMT), non-vital mineralized tissue (NVMT) and non-mineralized tissue (NMT) were quantified histomorphometrically. Peripheral blood was collected from the patients before FFHB placement and 6 months after the surgery for anti-HLA analysis. The histomorphometric analysis showed the presence of VMT, NVMT and NMT in 45.56 ± 15.72 %, 14.16 ± 13.39 % and 40.29 ± 12.60 %, respectively. The baseline and 6 months postoperative CTs revealed bone thickness in the order of 5.66 ± 0.67 mm and 8.71 ± 1.52 mm (3.05 ± 1.39 mm). The anti-HLA analysis revealed that two of the six patients (33.3 %) became sensitized, however this was not associated with any FFHB incorporation loss (p > 0.05). A total of 24 implants were placed all of which were osseointegrated after 6 months. Although FFHB-related HLA sensitization does not appear to affect bone incorporation when treating insufficient bone thickness for implant placement, further follow-up is required to determine whether there is an association between HLA sensitization and long-term graft survival.
Assuntos
Transplante Ósseo , Implantes Dentários , Antígenos HLA/imunologia , Parafusos Ósseos , Humanos , Titânio/farmacologia , Tomografia Computadorizada por Raios X , Transplante HomólogoRESUMO
Uma das maiores controvérsias relacionadas ao uso de osso alógeno relaciona-se à possível sensibilização imunogênica do paciente receptor. Isso, teoricamente, poderia causar rejeição, incorporação óssea lenta, osteólise, erosões ósseas, degeneração articular, infecção e fratura. Existem na literatura alguns trabalhos demonstrando indícios de sensibilização imunológica frente ao uso dos enxertos ósseos alógenos frescos congelados, com sensibilização da molécula HLA doador-específico. No entanto, há carência de trabalhos científicos que avaliem as possibilidades de sensibilização em humanos após transplante ósseo para fins de reconstrução, para posicionamento de implante dentário. Nosso grupo demonstrou em um trabalho recente a sensibilização para HLA em 33,3% dos pacientes receptores de transplante ósseo córtico-medular, porém, não existiu repercussão significativa da sensibilização na incorporação do enxerto, já que em todos os indivíduos da pesquisa os enxertos apresentaram boa incorporação e remodelação. Apesar da ausência de influência da sensibilização por HLA na incorporação dos enxertos ósseos, deve-se ponderar que uma parcela significativa dos pacientes (33,3%) foi sensibilizada, o que poderia acentuar a rejeição a futuros transplantes, como de fígado ou coração, portadores dos mesmos antígenos HLA (second-set rejection). Faz-se necessário o aprofundamento das investigações científicas sobre a possibilidade de sensibilização dos pacientes receptores de transplante ósseo para fins de reabilitação dentária por meio de implantes.
There is much controversy regarding the use of allogeneic bone in relation to the risk of immunogenic sensitization of the host. This could increase the chances of graft rejection, slow bone incorporation, osteolysis, bony erosions, joint degeneration, infection and fracture. Some studies have shown evidence of immunological sensitization, when using fresh frozen allogeneic bone grafts, against the donor-specific HLA molecule. However, there are only a few studies assessing the risk of sensitization in humans after bone grafting for bone reconstruction prior to dental implant placement. Our group has recently demonstrated a 33.3% rate of HLA sensitization in patients receiving a corticancellous bone graft, however, with no significant effect on graft incorporation, since all subjects in the study showed adequate incorporation and bone remodeling. Despite there being no influence of HLA sensitization in bone graft incorporation, it should be highlighted that a significant portion of patients (33.3%) was sensitized, which could jeopardize future transplants, such as liver or heart, from donors with the same HLA type (second-set rejection). Further investigation is necessary on the sensitization risk among patients receiving bone transplant for the purpose of dental rehabilitation using implants.