RESUMO
BACKGROUND: Several types of bone grafts are used in ridge preservation procedures. PURPOSE: To compare the healing of allografts and xenografts applied for alveolar ridge preservation. MATERIALS AND METHODS: Twenty volunteers in need of extraction of a single-rooted tooth prior to implant installation were randomized into two groups. One group received a deproteinized cancellous bovine bone xenograft embedded in a 10% collagen matrix and the other a demineralized freeze-dried cortical bone allograft. A collagen membrane was used to cover the grafts, flaps were sutured. At baseline and 6 months later, clinical measurements including vertical and horizontal bone dimensions were taken. Histomorphometric analysis was performed. RESULTS: Both groups showed shrinkage of bone dimensions. At mesial, center and distal sites, the vertical changes in dimension were -0.6, 0.5, and -0.1 mm for the allograft and -1.1, -0.4, and -0.9 mm for the xenograft. The horizontal changes in dimensions were -1.4 mm for the allograft and -2.6 mm for the xenograft. New bone and residual graft material were 25.5 ± 10.1% and 33.8 ± 9.4% at the allograft and 35.3 ± 16.8% and 22.2 ± 13.4% at the xenograft sites. None of the differences was statistically significant. CONCLUSION: Both grafting materials are suitable for the preservation of the alveolar ridge.
Assuntos
Aumento do Rebordo Alveolar/métodos , Transplante Ósseo/métodos , Adulto , Aloenxertos/patologia , Processo Alveolar/patologia , Processo Alveolar/cirurgia , Animais , Bovinos , Feminino , Xenoenxertos/patologia , Humanos , MasculinoRESUMO
BACKGROUND: Severe alveolar atrophy often presents a challenge for the implant surgery. The significant lack of bone in the alveolar ridges may compromise the final restorations both from the aesthetic and functional standpoints. OBJECTIVES: To evaluate the behavior of bone block allografts for the maxillary augmentation and to investigate its incorporation, remodeling, and implant survival rates in two different healing time points. MATERIAL AND METHODS: Sixty-six consecutive patients (52 female/14 male, mean age: 57.95 ± 9.06 years old), presenting 113 atrophic alveolar ridges underwent maxillary augmentation with fresh-frozen allogeneic bone blocks from tibia. Patients were randomly assigned in two groups: Group 1-patients who would wait 4 months for implant placement after grafting, and Group 2-patients who would wait 6 months. Events of infection, suture dehiscence or mucosal perforation were recorded. Cone-beam computed tomography scans were compared volumetrically between the time of the grafting surgery and reentry procedure after incorporation. Biopsies were collected and subjected to histological, histomorphometric and immunehistochemical analysis. RESULTS: A total of 305 implants were placed in the reconstructed sites. The mean resorption rate in Group 1 (13.98% ± 5.59) was significantly lower than Group 2 (31.52% ± 6.31). The amount of calcified tissue, newly formed bone and remaining graft particles demonstrated no difference between groups. The samples showed evident immunolabeling for the podoplanin protein in both groups. The implants cumulative survival rate was 94.76%. CONCLUSIONS: The findings of the present study indicate that there is a significant difference regarding the resorption of the grafts when waiting 4 or 6 months before placing the implants, even though no difference was found in the histological, histomorphometric, and immunohistochemical features. Both 4-month and 6-months healing times are suitable for the implant placement.
Assuntos
Perda do Osso Alveolar/cirurgia , Remodelação Óssea/fisiologia , Transplante Ósseo/métodos , Implantação Dentária Endóssea/métodos , Maxila/cirurgia , Boca Edêntula/cirurgia , Osseointegração/fisiologia , Levantamento do Assoalho do Seio Maxilar/métodos , Adulto , Idoso , Perda do Osso Alveolar/patologia , Reabsorção Óssea , Tomografia Computadorizada de Feixe Cônico , Prótese Dentária Fixada por Implante/métodos , Feminino , Humanos , Imageamento Tridimensional , Masculino , Maxila/patologia , Maxila/fisiopatologia , Pessoa de Meia-Idade , Boca Edêntula/fisiopatologia , Osteócitos/patologia , Fatores de TempoRESUMO
BACKGROUND: Bone allografts have shown satisfactory clinical results in alveolar ridge reconstructions. However, the process of incorporation and the resorption rates of these grafts are not yet fully understood. PURPOSE: The aim of this study was to use computed tomography (CT), histology, and histomorphometry to assess the time-dependent rates of resorption and incorporation of fresh-frozen bone allografts. MATERIALS AND METHODS: Twenty-four patients underwent alveolar ridge reconstruction with bone block allografts and were randomly allocated to three groups with different graft healing periods (4, 6, or 8 months) before implant placement. To assess the resorption rates, CT scans were acquired within 7 days after bone graft surgery and at the end of the period. Graft samples were collected and sent for histological and histomorphometric analyses. RESULTS: The graft resorption mean rates were 50.78% ± 10.43, 32.77% ± 7.84, and 13.02% ± 3.86 for the 4-, 6-, and 8-month groups, respectively, and were significantly different among the three groups. Newly formed bone with osteocytes near the grafted bone was observed in all three groups. The number of osteocytes was significantly lower at 4 months. Grafted bone remains were significantly higher in the shortest period of time. All of the grafts showed large amounts of calcified tissue. CONCLUSIONS: All three groups showed new bone formation and different bone resorption rates. Graft healing periods of 4 months showed less graft resorption and seemed to be the most favorable for implant placement. Healing periods of 8 months showed the largest rate of graft resorption, which could render the grafts unfavorable for implant placement.