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The aim of this study is to evaluate the efficacy of the application of allogenous bone at the maxillomandibular reconstructions for future rehabilitation with dental implants. The patients were submitted to reconstruction of maxilla, using allogeneic bone grafts, in 3 different techniques: onlay grafts for lateral ridge augmentation, onlay and particulate bone for sinus lift grafting, and particulate alone for sinus lift grafts. Clinical and radiographic control was done at the postoperative phase for at least 8 months, until the patient could be submitted to the installation of dental implants. The results showed success in the majority of the cases, and dental implants could be installed. This can be considered an excellent alternative when compared with the use of autogenous grafts; because handling is easier, there is a great amount of material available and a possibility of using local anesthesia, and consequently there is a reduction of patient morbidity.
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J Oral Maxillofac Surg
66:2335-2338, 2008
Use of Allogeneic Bone Graft in Maxillary
Reconstruction for Installation of
Dental Implants
Kelston Ulbricht Gomes, DDS,* João Luiz Carlini, DDS, PhD,†
Cássia Biron, DDS,‡ Abrão Rapoport, MD, PhD,§ and
Rogério A. Dedivitis, MD, PhD
The aim of this study is to evaluate the efficacy of the application of allogenous bone at the maxillo-
mandibular reconstructions for future rehabilitation with dental implants. The patients were submitted
to reconstruction of maxilla, using allogeneic bone grafts, in 3 different techniques: onlay grafts for lateral
ridge augmentation, onlay and particulate bone for sinus lift grafting, and particulate alone for sinus lift
grafts. Clinical and radiographic control was done at the postoperative phase for at least 8 months, until
the patient could be submitted to the installation of dental implants. The results showed success in the
majority of the cases, and dental implants could be installed. This can be considered an excellent
alternative when compared with the use of autogenous grafts; because handling is easier, there is a great
amount of material available and a possibility of using local anesthesia, and consequently there is a
reduction of patient morbidity.
© 2008 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg 66:2335-2338, 2008
It is estimated that in the United States 40,000 persons
receive allogeneic grafts in the maxillomandibular re-
gion annually. Because of the development of special-
ized centers in the manipulation and processing of
skeletal tissues, the use of allogeneic grafts became an
alternative for the treatment of the atrophic maxilla
and mandible.
Osteogenesis is the most important basic principle
for total integration of bone grafts. The new bone
from the patient is produced by the osteoinduction
process, whereby mesenchymal cells differentiate
into osteoblast cells that produce new bone. This differ-
entiation process is coordinated by glycoproteins, such
as bone morphogenetic protein (BMP). BMPs are
present in both autogenous and allogeneic bone. The
process of osteoinduction determines the 3-dimensional
growth of capillary vessels, perivascular tissues, and os-
teoprogenitor cells from the patient to the graft.
The incorporation process of the graft happens
through the gradual replacement of bone until the
formation of new bone occurs, and this comprises 5
stages, beginning with the acute inflammatory pro-
cess, with gradual substitution by granulation tissue
and an increase in osteoclast activity.
The second and third stages are the incorporation
phase, which lasts several weeks and includes vascu-
*Postgraduation Student, Postgraduation Course on Health Sci-
ences, Heliopolis Hospital, São Paulo, and Maxillofacial Surgeon,
Center for Integral Assistance of Cleft Lip and Palate Patients,
Curitiba, Brazil.
†Professor, Maxillofacial Surgery Department, Federal University
of Paraná, and Head of Maxillofacial Surgery Service, Center for
Integral Assistance of Cleft Lip and Palate Patients, Curitiba, Brazil.
‡Maxillofacial Surgeon, Center for Integral Assistance of Cleft Lip
and Palate Patients, Curitiba, Brazil.
§Full Professor, Department of Surgery, University of São Paulo
Medicine School, and Coordinator, Postgraduation Course in
Health Sciences, Heliopolis Hospital, São Paulo, Brazil.
Postgraduation Course of Otorhinolaryngology and Head and
Neck Surgery, Federal University of São Paulo–Escola Paulista de
Medicina, and Professor, Postgraduation Course on Health Sci-
ences, Heliopolis Hospital, São Paulo, Brazil.
Address correspondence and reprint requests to Dr Gomes: De-
partment of Oral and Maxillofacial Surgery, Center for Integral Assis-
tance of Cleft Lip and Palate Patients, Rua Bruno Filgueira 369, Con-
junto 1402, CEP 80240-220 Bairro Batel, Curitiba, Paraná, Brazil;
©2008 American Association of Oral and Maxillofacial Surgeons
larity and osteoinduction. During this phase, the im-
munologic system of the patient becomes sensitive to
the donor antigenicity, going through remodeling and
ending with an efficient structure. At this phase, the
medullary bone is totally reabsorbed and substituted,
and the cortical bone may remain even if partially
The incorporation phase, characterized by osteoin-
duction and osteoconduction of allogeneic graft, is
slower than the same process when autogenous graft
is used, because of the immunologic response of the
patient. After 4 or 6 weeks, osteogenesis begins. After
1 year, the differences between allogeneic and autog-
enous grafts decrease.
The purpose of this study is to evaluate the appli-
cation of allogeneic bone for maxillary reconstruction
for future rehabilitation with dental implants.
Patients and Methods
We evaluated 28 patients who underwent allo-
graft surgery for maxillary reconstruction. The allo-
geneic bones used were obtained from the Bank of
Tissues and Bone of the Clinical Hospital of the
Federal University of Paraná, Brazil. The postoper-
ative follow-up ranged from 1 year to 6 years, with
implants and prostheses being functional through-
out the follow-up period.
The patients underwent reconstruction of maxilla,
by use of allogeneic bone grafts, via 3 different tech-
niques: onlay grafts for lateral ridge augmentation,
onlay and particulate bone for sinus lift grafting, and
particulate bone alone for sinus lift grafting (Fig 1).
Onlay Grafts
For onlay grafts, after the allogeneic bone had been
received from the Bank of Tissues and Bone, it was
manipulated with sterilized instruments. This phase
consists of preparation of the bone graft, usually har-
vested from a human femur, so that it fits the alveolar
defect. With the use of a reciprocating saw, the bone
was cut into block pieces (Fig 2); then it was safely
stored until it could be placed in the patient.
Particulate Grafts
For particulate bone grafts, the allogeneic bone was
cut into block pieces. Then, with the use of a specific
grinder instrument, the bone blocks were made into
particulate bone, and this was safely stored until it
could be used in the patient.
Onlay Grafts for Lateral Ridge Augmentation
The first technique was used when there was suf-
ficient bone height to receive a dental implant but the
alveolar ridge was not wide enough.
The patient underwent local anesthesia in the area
of the procedure; then, with the use of a scalpel, an
incision was made so that a mucoperiosteal flap could
be released from the bone below. The recipient area
was prepared, and by use of round burs, perforations
were made to improve blood supply to the graft. The
block bone grafts, which had been prepared previ-
ously, were then adjusted to the recipient area and
fixated with 2 titanium screws, 1.5 mm in diameter, in
each block bone. Sharp areas from the grafts were
removed with round burs. Sutures were made with
FIGURE 2. Allogeneic bone.
Gomes et al. Allogeneic Bone and Maxillary Reconstruction.
J Oral Maxillofac Surg 2008.
FIGURE 1. Preoperative radiograph.
Gomes et al. Allogeneic Bone and Maxillary Reconstruction.
J Oral Maxillofac Surg 2008.
Nylon No. 4 (Ethicon; Johnson & Johnson, Somerville,
NJ) and were kept in place for at least 14 days (Fig 3).
Onlay and Particulate Bone for Sinus
Lift Grafting
The second technique was used in the maxilla
when there was not enough height and width in the
area suggested to receive dental implants.
The patient received the same preparation with
local anesthesia. A mucoperiosteal flap was made, and
by use of a round bur, access to the maxillary sinus
was established. A specific instrument was used to
undermine and detach the sinus membrane so that it
could be lifted and allowed for loading with particu-
late bone, which had been prepared previously. This
procedure would recover the height of the area that
would receive the dental implants.
To promote the augmentation of the alveolar ridge,
especially at the anterior portion of the maxilla, the
bone blocks were used, in the same manner as de-
scribed previously.
The mucoperiosteal flap was released to cover the
surgical area without tension, by making relaxing in-
cisions and scoring the periosteum.
Particulate Bone Alone for Sinus Lift Grafting
The third technique was used every time there was
an intention to recover only the bone height at the
area that would receive the dental implants.
After preparation of the patient and allogeneic
bone as described previously, the maxillary sinuses
were filled with particulate bone at the area that
needed to recover its height.
A period of at least 8 months was planned before
the patient could be submitted to the installation of
dental implants.
Clinical and radiographic examination was done
during the postoperative phase.
Eight cases of maxillary reconstruction, for lateral
ridge augmentation, were performed by use of onlay
grafts only. All cases were successful, and the dental
implants were installed (Table 1). In 7 cases, sinus
lifting with bone grafting was done, but dental im-
plants could only be installed in 5 patients. The other
2 patients underwent new reconstruction surgery. In
another 13 patients sinus lift bone grafting with allo-
geneic onlay and particulate bone grafts was done. It
was not possible to install dental implants in 2 cases.
Some authors believe that the principal concern
regarding, and disadvantage of, allografts is risk of
infectious disease transmission, such as acquired im-
munodeficiency syndrome.
On the other hand, it is
FIGURE 3. Allogeneic bone grafts placed on the alveolar ridge of
the maxilla.
Gomes et al. Allogeneic Bone and Maxillary Reconstruction.
J Oral Maxillofac Surg 2008.
No. of
Cases Male Female
Success (Installation
of Dental Implants)
Shortest Time
of Follow-up
Longest Time
of Follow-up
Lateral ridge augmentation
with allogeneic onlay
grafts 8 3 5 8 1 yr 4 yr
Sinus lift bone grafts with
allogeneic particulate
bone grafts only 7 3 4 5 1 yr 6 yr
Sinus lift bone grafts with
allogeneic onlay grafts
and particulate bone
grafts 13 3 10 11 1 yr 5 yr
Total 28 6 19 24
Gomes et al. Allogeneic Bone and Maxillary Reconstruction. J Oral Maxillofac Surg 2008.
also stated that adequate material processing, includ-
ing freezing, demineralization, and lyophilization, can
decrease the risk of infection transmission.
Allograft has some advantages, such as easy manip-
ulation, great amount of material available, possibility
of local anesthesia for the procedure, cost reduction,
and morbidity reduction, because the use of another
donor site is not necessary.
When allograft is com-
pared with autogenous grafts, differences cannot be
observed at the final stage of incorporation with re-
gard to histology.
Research to evaluate the immunologic response,
performed in patients undergoing allograft surgery,
has shown no presence of antibodies in blood sam-
ples. Use of local anesthesia, the great amount of
material available, no need for a donor site, and cost
reduction are pointed to as the advantages of alloge-
neic grafts. However, the potential for infectious dis-
ease transmission is a disadvantage.
However, the
possibility of disease transmission with lyophilized
allograft and frozen cartilage was evaluated. Three
forms of virus were considered— human immunode-
ficiency virus, the viruses associated with Creutzfeldt-
Jakob disease, and the viruses associated with hepati-
tis B and C; up to 1993, no case had been found.
When allogeneic bone grafts are used for recon-
struction, the amount of time required for revascular-
ization is longer than that with reconstruction with
autogenous bone.
This is likely due in part to the
immunologic response. Fresh bone presents a better
immunologic response. Freezing and lyophilization
preserve properties to improve the chance of graft
On the basis of an analysis of the literature, as
described previously, many advantages of the use of
allogeneic grafts for maxillomandibular reconstruc-
tion can be listed, especially when it is compared
with the use of autogenous grafts. Handling is easier,
there is a great amount of material available, and there
is a possibility of using local anesthesia; consequently,
there is a reduction of patient morbidity. After all, it
was found in this study that in most of the patients,
dental implants could be installed, so the use of allo-
geneic bone graft can be considered a good alterna-
tive in this type of treatment.
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facial deformities. Ann Surg 194:366, 1981
3. Köndell PA, Mattsson T, Astrand P: Immunological responses
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4. Perrott DH, Smith RA, Kaban LB: The use of fresh frozen
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5. Marx RE, Carlson ER: Tissue banking safety: Caveats and pre-
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7. Maletta JA, Gasser JA, Fonseca RJ, et al: Comparison of the
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Maxillofac Surg 41:487, 1983
8. Urist MR: Bone: Formation by autoinduction. Science 150:893,
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... Indeed, the reported morbidity rate for the donor site is approximately 20% in all cases [10,11]. Furthermore, the amount of graft material is restricted, and sufficient amounts of autografts are often not available for massive grafts [12,13]. ...
... HR-MS: calc. EM + Na: 441.1520 g/mol; found: 441.1517 g/mol. 1 13 ...
... • C. HR-MS: calc. EM + Na: 233.0784 g/mol; found: 233.0718 g/mol. 1 13 In the last step of the synthesis for ArMA, photopolymerizable groups were attached. Therefore, MB5 (1.7 g, 8.1 mmol), MEHQ (1000 ppm), phenothiazine (300 ppm) and triethylamine (2.46 g, 24.3 mmol) were dissolved in dry THF (200 mL), cooled with an ice bath in a three-necked round bottomed flask and purged with argon. ...
In tissue engineering (TE), artificial biomaterials have emerged over the past decade as an alternative to autotransplants. The main characteristics of these materials include good biocompatibility as well as biodegradability. Up to now, most materials used in TE are based on polyesters, which are limited in their scope of application, especially as scaffolds, due to their undesirably slow degradation behavior under acidic conditions present, e.g. during the process of hydroxyapatite resorption during bone regeneration. Furthermore, the formation of acidic degradation products can lead to tissue inflammation or even necrosis. Therefore, alternatives to ester functionalities, which show enhanced degradability under acidic conditions, are of interest. Herein, we present the synthesis of linear and cyclic acetal-based monomers for photopolymerizable materials. The reactivity and mechanical properties of polymer networks derived from these monomers were investigated. Moreover, their degradation behavior compared to ester-based polymer networks was explored. Degradation studies of the model compounds showed that the synthesized acetals degrade 80 to 200 times faster than their ester counterparts. A subsequent in vitro degradation study of polymer networks based on these compounds confirmed the potential of acetals moieties in polymeric biomaterials for bone regeneration.
... Different intraoral donor sites are widely used as bone blocks or particulate bone. The most common intraoral sites are the symphysis and ramus/retromolar area [18][19][20][21][22], they have different degrees of morbidities and complications [23][24][25][26][27]. Non-autogenous bone grafts such as allografts, xenografts, and synthetic bone substitutes are widely used either alone or in combinations [28][29][30][31][32][33][34]. They eliminate the potential complications associated with autogenous donor sites and their availability is unlimited, however, they have osteoconductive characteristics and lack of osteoprogenitor cells. ...
Full-text available
Autogenous bone is still considered the gold standard in bone augmentation for implant insertion in atrophic ridges. However, augmentation of multiple edentulous atrophic segments usually necessitates the use of extraoral donor sites. This chapter introduces the Wedge Technique, as a new bone augmentation method that can augment multiple edentulous ridges with intraoral cortical bone grafts. Patients with moderate to severe ridge atrophy in different regions of the jaws were treated with the wedge technique (WT). Patients received a panoramic radiograph immediately after the surgery, and they were examined clinically and radiographically (periapical radiograph) every 2 weeks. At four months, CBCT was performed to evaluate the bone gain. Reentry was performed after 4 to 5 months to evaluate the new bone volume and quality and to insert implants. The follow-up period ranged from 30 to 120 months. The healing process was uneventful, with minimal morbidity. The success rate was 95%, the bone gain average was 3–6 mm vertically and 3–9 mm horizontally. The wedge technique can augment multiple segments of atrophic ridges with a small amount of autogenous graft. The achieved bone volume was satisfying, especially that the majority of the augmented areas were at posterior mandibular defects.
... Allogeneic bone grafts, whether fresh, frozen, or freeze-dried, have several advantages, including reduced surgical morbidity, shorter operating times, and greater availability and quantity per autogenic bone [1,2]. Histological and histomorphometric results show that allogeneic bone has osteoconductive properties like autogenic bone [3]. ...
... Compared to autografts, allografts provide a great means to restore bone with stable occlusion, require less maintenance (donor site morbidity), and result in great patient satisfaction. 5,6 Conclusion Preoperative information on the patient's presenting condition ensures a successful treatment outcome with longterm uneventful functionality. Osseous augmentation for bone volume and quality is essential. ...
Full-text available
Kavish A Gurjar State of the Art Dental Group, Rockville, MD, 20850, USACorrespondence: Kavish A GurjarState of the Art Dental Group, Rockville, MD, 20855, USATel +1 8187465914Email Drkavishagurjar@gmail.comAbstract: A deficient maxillary edentulous ridge volume can be augmented by onlay grafting technique for implant placement to support fixed hybrid screw retained prosthesis. Various techniques have been used to correct defective bone. These augmentation techniques include inlay and onlay grafts, bone splitting osteotomy, and distraction osteogenesis, among others. Successful reconstruction depends on multiple biological factors as well as patient compliance. Here, I report a case of ridge augmentation using onlay cortico-cancellous particulate bone grafting, resorbable collagen membrane, and bone tac pins, followed by surgical implant placement with multiunit abutments to support the fixed prosthesis.Keywords: atrophy, medullary bleeding, dental implant, ridge augmentation, bone grafting, guided bone regeneration, GBR, collagen membrane
... The safety of allogeneic, sterilized bone transplants regarding disease transmission, the biological tolerance, potential graft rejection and allosensitization is well known since allogeneic bone transplants (e.g. bone chips, bone blocks) are widely used in regenerative, maxillofacial and orthopedic medicine [4][5][6][7]. ...
Full-text available
Introduction The allogeneic bone screw transplant is a new osteosynthesis device making the use of foreign fixation material obsolete for various kinds of indications. Moreover, it is integrated into the recipient bone by natural bone remodeling without harming the surrounding tissue. The aim of this study was to determine the efficacy and safety of the transplant for osteotomy and arthrodesis in hand and foot surgery and to evaluate the clinical importance of the device. Materials and methods A single-surgeon case series of 32 patients who had undergone hand or foot surgery with the application of an allogeneic bone screw with an average follow-up time of 1 year is reported. Clinical data were reviewed to evaluate the pain levels and satisfaction of the patients and the frequency and type of complications occurring during the healing process. Routine radiography and computed tomography were reviewed to determine the fusion rate, the ingrowth behavior of the transplant and the possible occurrence of transplant failure. Results High patient satisfaction was paired with low postoperative pain levels and a low complication rate. 97% of the patients were free of pain at the timepoint of the second follow-up examination, the mean time of recovery of full mobility was 50.1 ± 26.1 days after surgery. Wound healing disturbance occurred only in two cases. Bony consolidation of the osteotomy or arthrodesis gap as well as osseointegration of the transplant was seen in all cases. No transplant failure or transplant loosening occurred. Conclusions The application of the allogeneic bone screw resulted in a 100% fusion rate while the patient burden was low. The transplant is safe and suited for various kinds of osteosynthesis in hand and foot surgery.
Bone graft materials have mixed effects of bone repair in the field of oral maxillofacial surgery. The qualitative analyses performed by previous studies imply that autogenous odontogenic materials and autogenous bone have similar effects on bone repair in clinical jaw bone transplantation. This retrospective systematic assessment and network meta-analysis aimed to analyze the best effect of clinical application of autogenous odontogenic materials and autogenous, allogeneic, and xenogeneic bone grafts in bone defect repair. A systematic review was performed by searching the PubMed, Cochrane Library, and other journal databases using selected keywords and Medical Subject Headings search terms. 10 Papers (n = 466) that met the inclusion criteria were selected. The assessment of heterogeneity did not reveal any overall statistical difference or heterogeneity (P = 0.051 > 0.05), whereas the comparison between autogenous and allogeneic bone grafts revealed local heterogeneity (P = 0.071 < 0.1). Risk of bias revealed nine unclear studies and one high-risk study. The overall consistency was good (P = 0.065 > 0.05), and the local inconsistency test did not reveal any inconsistency. The publication bias was good. The confidence regarding the ranking of bone graft materials after GRADE classification was moderate. The effects on bone repair in the descending order were as follows: autogenous odontogenic materials, xenogeneic bone, autogenous bone, and allogeneic bone. This result indicates that the autogenous odontogenic materials displayed stronger effects on bone repair compared to other bone graft materials. Autogenous odontogenic materials have broad development prospects in oral maxillofacial surgery.
Bone is a rigid, highly vascularized connective tissue that forms our skeleton. It is a dynamic composite material that is constantly being resorbed, redeposited, and remodeled to accommodate the mechanical and biological demands on the body. While bone has a remarkable innate capacity for repair and regeneration, the process of healing fractures can take months or years, thereby disrupting function and quality of life for patients. Moreover, several mechanical, pathological, and nutritional factors can further impair the bone healing process and present major clinical challenges for treating and ensuring robust healing of bone injuries and defects. The current standard of treatment involves stabilizing fractures and defects with artificial implants and fixation devices, typically composed of metals or ceramic materials. Bone grafts such as autografts and allografts offer improved osteoconductivity, biocompatibility, and host-implant osseointegration compared to the traditional implant materials. However, these grafts are limited in their availability and consistency between patients and donors. Bone tissue engineering promises new, diverse, and versatile strategies for encouraging bone repair and regeneration. The core components of tissue engineering approaches are cells, growth factors, scaffolds, and biophysical signals. These components may be employed individually or in combination with one another. Cell therapies for bone tissue engineering include the injection or delivery of stem cells (e.g., mesenchymal stem cells) to the fracture site, in order to assist nearby cells in the bone repair process. Growth factors such as BMP-2, IGF, and VEGF can be administered or released into bone defects at supraphysiological doses to promote native or implanted cells to accelerate bone repair. Bone tissue engineering scaffolds are often polymeric or ceramic materials which provide a framework for bone healing and can harbor cells at the defect site. The mechanical, chemical, topographical, and degradative properties of scaffolds can be engineered to encourage cell attachment, proliferation, and differentiation or perform controlled growth factor delivery. In addition, advances in scaffold fabrication techniques, such as 3D printing, have made the design of patient-specific scaffolds more feasible. Beyond the use of cells, growth factors, and scaffolds in bone tissue engineering, new approaches have recently been developed which utilize physical or mechanical stimulation to facilitate bone repair and regeneration. Bone is one of the several musculoskeletal tissues that are capable of adapting and responding to mechanical signals. Numerous studies have evaluated the in vitro and in vivo effects of several kinds of mechanical stimulation on bone, including cyclic tensile and compressive strain, pulsatile and oscillatory fluid flow, and low-intensity pulsed ultrasound. Variations in the intensity, frequency, and duration of these stimuli can elicit different cellular responses related to osteogenesis, bone matrix deposition, and mineralization. In these stimuli-based tissue engineering approaches, stem cells are implanted in nontraditional scaffolds, such as soft, deformable, biopolymer hydrogels, through which mechanical forces can propagate and be transmitted to cells. Overall, tissue engineering provides new strategies for enhancing the repair and regeneration of bone, which may translate to improved clinical outcomes for patients suffering from bone fractures and defects.
Autogenous odontogenic materials are a new, highly biocompatible option for jaw restoration. The inorganic component of autogenous teeth acts as a scaffold to maintain the volume and enable donor cell attachment and proliferation; the organic component contains various growth factors that promote bone reconstruction and repair. The composition of dentin is similar to that of bone, which can be a rationale for promoting bone reconstruction. Recent advances have been made in the field of autogenous odontogenic materials, and studies have confirmed their safety and feasibility after successful clinical application. Autogenous odontogenic materials have unique characteristics compared with other bone-repair materials, such as the conventional autogenous, allogeneic, xenogeneic, and alloplastic bone substitutes. To encourage further research into odontogenic bone grafts, we compared the composition, osteogenesis, and development of autogenous odontogenic materials with those of other bone grafts. In conclusion, odontogenic bone grafts should be classified as a novel bone substitute.
The healing and revascularization of onlayed autologous and lyophilized allogeneic rib grafts to the edentulous maxilla in the Macaca fascicularis monkey were studied using clinical, histologic, and microangiographic methods at varying intervals of up to eight months. Results indicated that healing and revascularization were similar but resorption of the allografts occurred approximately three months later than resorption of the autografts. Both grafting systems appeared to have minimal osteogenic potential. Osteoinduction and the final bony augmentation obtained were less than were seen with comparable autologous and allogeneic interpositional grafts.
A method for mandibular bone grafting that uses a combination of SDAB and particulate autologous cancellous bone and marrow is presented. The results of this treatment in four patients are described. Two additional maxillary bone grafts that use only SDAB are also reported. Grafts that are a combination of SDAB and cancellous autologous bone and marrow are biocompatible, anatomically contoured, easily adapted at surgery, and the allogeneic component is biodegradable. They do not require elaborate internal metallic devices for structural support.
The use of fresh frozen bone (FFB) alone, or in combination with autogenous bone (AB), for bony augmentation of the maxilla and mandible in preparation for dental reconstruction with endosseous implants has been studied. Ten patients received FFB +/- AB for augmentation of a severely atrophic mandible (n = 6) or for reconstruction of a jaw defect secondary to trauma or tumor resection (n = 4). Average follow-up was 26.3 +/- 5.4 months. At the time of implant placement, the bone grafts were found to be firm in consistency, well incorporated, and well vascularized in all 10 patients. Twenty-nine endosseous implants were placed an average of 8.3 +/- 3.1 months following bone grafting. One implant failed and was replaced, and one implant remains buried as a nonfunctional unit. All patients have been restored prosthetically by means of 28 of the 29 implants. This preliminary study indicates that FFB may be used alone or in combination with autogenous bone for augmentation or reconstruction of the atrophic maxilla and mandible. The resultant ridge is adequate to support loaded endosseous implants. A potential disadvantage is the minimal risk of disease transmission.
This study demonstrates by a virologic culture method that human immunodeficiency virus (HIV) resides in bone. After freezing, some initially positive specimens no longer yielded virus, but those that continued to yield virus were not further altered by subsequent washing, which removed essentially all marrow, or by freeze-drying. The safeguards against potential transmission of HIV by a bone allograft are principally the screening and testing methods previously described, although there may be a further reduction of the remote residual risk by the freezing step in the usual technical sequence for tissue banking by sterile techniques.
The clinical outcome of bone grafting procedures depends on many factors, including type and fixation of the bone graft as well as the site and status of the host bed. Bone grafts serve one or both of two main functions, as a source of osteogenetic cells and as a mechanical support. Autografts, both cancellous and cortical, are usually implanted fresh and are often osteogenetic, whether by providing a source of osteoprogenitor cells or by being osteoinductive. The latter is a process whereby the transplanted tissue induces mesenchymal cells of the recipient to differentiate into osteoblastic cells. Cortical grafts, whether autogeneic or allogeneic, at least initially act as weight-bearing space fillers or struts. All bone grafts are initially resorbed, but cancellous grafts are completely replaced in time by creeping substitution, while cortical grafts remain an admixture of necrotic and viable bone for a prolonged period of time. The three-dimensional framework, which supports invasion of the bone grafts by capillaries and osteoprogenitor cells, termed "osteoconduction", is another important function of both autografts and allografts. Fresh allografts are more slowly and less completely replaced by host bones because they invoke both local and systemic immune responses that diminish or destroy the osteoinductive and conductive processes. Although freezing or freeze-drying of allografts improves acceptance, their failure rate is still too high. These processes are also influenced by the vascularity and composition of the host bed. Thus, the interaction of the host and the bone graft determines the success of these procedures, which ultimately is to provide a mechanically efficient support structure.
Wandering histiocytes, foreign body giant cells, and inflammatory connective-tissue cells are stimulated by degradation products of dead matrix to grow in and repopulate the area of an implant of decalcified bone. Histiocytes are more numerous than any other cell form and may transfer collagenolytic activity to the substrate to cause dissolution of the matrix. The process is followed immediately by new-bone formation by autoinduction in which both the inductor cells and the induced cells are derived from ingrowing cells of the host bed. The inductor cell is a descendant of a wandering histiocyte; the induced cell is a fixed histiocyte or perivascular young connective-tissue cell. Differentiation of the osteoprogenitor cell is elicited by local alterations in cell metabolic cycles that are as yet uncharacterized.
The biomechanical properties of allograft bone can be altered by the methods chosen for its preservation and storage. These effects are minimal with deep-freezing or low-level radiation. Freeze-drying, however, markedly diminishes the torsional and bending strength of bone allografts but does not deleteriously affect the compressive or tensile strength. Irradiation of bone with more than 3.0 megarad or irradiation combined with freeze-drying appears to cause a significant reduction in breaking strength. These factors should be considered when choosing freeze-dried or irradiated allogeneic bone that will be subjected to significant loads following implantation.
Two major problems in maxillocraniofacial surgery are the limited amount of fresh autogenous bone, the standard material for bone grafting, and the resorption of the grafted bone. Experimental studies with demineralized, devitalized bone matrix have shown induction of endochondral ossification. Fifty-five demineralized allogeneic implants have been used in 44 patients over the past two years for a variety of congenital (n = 37) and acquired (n = 7) defects. The allogeneic bone was obtained from cadavers, prepared as powders, chips or blocks, and was demineralized. After having been sterilized by irradiation, they were used to augment contour, fill defects, or construct bone within soft tissue. Of implanted sites that could be evaluated by physical examination, 31 of 31 were solid by three months. By radiographic examination three of 19 were healed by three months, and an additional 11 were positive by six months. Induced bone was seen in four of four biopsy specimens. Infection occurred in four of 44 patients (9%), comparable with conventional grafts. Implant resorption occurred in four instances. Allogeneic demineralized implants offer several advantages over conventional bone grafting, such as avoidance of a harvesting operation, ease of manipulation, and potentially unlimited material in banked form. In addition, healing by induced osteogenesis may bypass the resorption seen with healing of mineral-containing grafts.
Oral and maxillofacial reconstructive surgeons using allogeneic tissues have expressed justifiable concern over the safety of these tissues as they relate to the transmission of infectious disease. This report reviews cases of infectious disease transmission from inadequately screened donors of allogeneic tissues, as well as those related to improper sterilization and cataloging of these tissues. It is concluded that good judgment and attention to good science on the part of the tissue bank as well as the surgeon can maximize the ability to place contamination-free specimens, thereby avoiding complications similar to those described.