An update on bone substitutes for spinal fusion

With the current advances in spinal surgery, an understanding of the precise biological mechanism of each bone substitute is necessary for inducing successful spinal fusion. In this review, the categories of bone substitutes include allografts, ceramics, demineralized bone matrix, osteoinductive factors, autogenous platelet concentrate, mesenchymal stem cells, and gene therapy. Further, clinical studies have been evaluated by their levels of evidence in order to elucidate the precise effect of the bone substitute employed and to establish clinical guidance. This article will review both clinical studies based on evidence and basic research in current advances in order to avoid as far as possible any chances of failure in the future and to understand cellular biology in novel technologies.

Vertical ridge augmentation using xenogenous bone blocks: a histomorphometric study in dogs

PURPOSE

Because vertical ridge augmentation with autogenous bone blocks carries with it a risk of graft resorption and donor site morbidity, the aim of the present study was to compare histologically the healing following vertical ridge augmentation using screwable, xenogenous deproteinized blocks or autologous bone blocks in dogs.

MATERIALS AND METHODS

Standardized vertical mandibular defects were surgically created in edentulous ridges of six foxhounds. Two bone blocks (6 x 10 x 15 mm) were inserted on each mandibular side and fixed with both a titanium implant and an osteosynthetic screw. Three different therapies were tested: (1) xenogenous block alone; (2) xenogenous block, covered with a chemically cross-linked collagen membrane; and (3) autologous blocks, harvested during defect preparation. After 3 months of submerged healing, the miniscrews were removed and replaced by dental implants. Following an additional healing period of 3 months, the animals were sacrificed, and dissected blocks were prepared for histomorphometric analysis.

RESULTS

During the primary healing period, three of 12 hemimandibles (six blocks) had to be removed because of severe inflammatory reactions (two xenogenous block sites with collagen membrane, one autologous block site). In general, histologic analysis revealed that xenogenous blocks, used alone or combined with a collagen membrane, exhibited osteoconductive properties on a level equivalent to that of autologous blocks, resulting in means of 50% to 60% of ossification of the blocks. Some parts of the xenograft were encased in soft tissue, partly surrounded by multinuclear giant cells. However, all groups showed obvious signs of bone/graft resorption.

CONCLUSIONS

Within the limits of the present study, it was concluded that the examined screwable xenogenous bone block might be a useful scaffold for ridge augmentation procedures. However, the combination of xenogenous blocks with a cross-linked collagen membrane did not appear to improve outcomes.

Analysis of the healing process in sinus bone grafting using various grafting materials

OBJECTIVES

The purpose of this study was to compare differences in the healing process in the sinus bone grafting using various grafting materials.

STUDY DESIGN

Maxillary sinus bone grafts were divided into 4 groups according to the graft material used: group I, a mixture of autogenous bone and BioOss (Osteohealth Co., Shirley, NY); group II, a mixture of BioOss and Orthoblast II (Greencross; Isotis); group III, BioOss only; and group IV, synthetic bone, Osteon (Genoss, Korea), only. To evaluate the healing status of the graft surgery, bone specimens were collected from the lateral sinus using a 2.0-mm trephine bur at 4 and 6 months after surgery. Histology of the bone specimens was prepared, and the percentage of newly formed bone fraction, lamellar bone/woven bone ratio (LB/WB), and newly formed bone/graft material ratio (NB/GM) were measured to indicate the suitability of the materials and the healing of the grafts.

RESULTS

The LB/WB ratio and NB/GM ratio were markedly increased at 6 months compared with the values at 4 months. It was observed that good bone healing was achieved even for grafts of xenogeneic bone only or synthetic bone only. Cases grafted with a mixture of allogeneic and xenogeneic bone showed no great advantage regarding bone healing.

CONCLUSION

The results indicated that grafts of xenogeneic or synthetic bone can be effective for sinus bone grafting.

The effects of resorbable membrane on human maxillary sinus graft: a pilot study

PURPOSE

To investigate the effects of resorbable membrane on new bone formation in human maxillary sinus graft using anorganic bovine bone material histomorphometrically in a split-mouth study design.

MATERIALS AND METHODS

This prospective pilot study included six patients who required bilateral sinus augmentations prior to implant treatment. Each patient was grafted with anorganic bovine bone (Bio-Oss). The experimental side was covered with resorbable membrane (Bio-Gide) over the grafted sinus, and the control side was left uncovered. After 8 months of healing (range, 7 to 9 months), implants were placed. Biopsy samples were obtained from each side through the previously grafted sinus window and evaluated. Statistical analysis was performed using the Mann-Whitney U test at a significance level of alpha = .05.

RESULTS

The control side appeared to have a significantly greater amount of soft tissue than the experimental side (P = .026), whereas no significant differences in the amount of new bone were observed (P = .937).

CONCLUSION

Resorbable membranes significantly reduced the amount of soft tissue formed in the sinus grafted with anorganic bovine bone material but had no effect on new bone formation.

Efficacy of vascularized periosteal membranes in providing soft tissue closure at grafted human maxillary extraction sites

PURPOSE

Soft tissue closure is mandatory for optimal healing of extraction sites treated via guided bone regeneration. The objective of this study was to evaluate the efficacy of a flap design based on the extension of palatal tissues to obtain and maintain soft tissue coverage over grafted extraction sockets.

MATERIALS AND METHODS

Adult patients (n = 22) with at least two teeth indicated for extraction were treated. After atraumatic extraction, control sockets were filled with a composite graft (1:1) containing demineralized freeze-dried bone allografts and Bio-Oss. Experimental sockets were treated identically, except that an Atrisorb absorbable barrier membrane was also placed over the graft material before flap closure, which was obtained, in all sockets, by the coronal extension of a vascularized pedicle dissected from the periosteal aspect of the palate.

RESULTS

Primary tension-free wound closure was achieved at all treated sites. Exfoliation of the graft material during healing was not observed in either treatment group. High levels of soft tissue closure were maintained throughout the study period for both treatment groups, and membrane exposure was observed in only 7% of treated sites.

CONCLUSION

On the basis of this study it appears that the reported technique was an adequate method of achieving and maintaining complete soft tissue coverage and promoting healing by primary intention in grafted extraction sockets in humans.

[A preliminary study of high viscous chitosan/glycerol phosphate with demineralized bone matrix to repair cartilage defects in rabbits]

OBJECTIVE

To evaluate the effect of implantation of the complex of high viscous chitosan/glycerol phosphate with demineralized bone matrix (HV-C/GP-DBM) in repairing cartilage defects of rabbits.

METHODS

HV-C/GP-DBM was prepared by compounding HV-C/GP and DBM by 2:1 (W/W). Twenty-four 34-week-old New Zealand white adult rabbits, weighing 3.5-4.5 kg, were included. A bit with the diameter of 3.5 mm was used to drill 3-cm-deep holes in both sides of femoral condyle to make cartilage defects. The complex of HV-C/GP-DBM was then injected into the right holes as the experimental group and the left ones serve as the control group. The rabbits were killed at 4, 8 and 16 weeks after the operation, respectively. The obtained specimens were observed macroscopically, microscopically and histologically. According to the International Cartilage Repair Society Histological Scoring (ICRS), the effect of cartilage repair was assessed at 16 weeks postoperatively.

RESULTS

At 4-8 weeks postoperatively, in the experimental group, the defects were filled with hyaline cartilage-like tissues; the majority of chitosan degradated; and the DBM particles were partly absorbed. However, in the control group, there were small quantities of discontinuous fibrous tissues and maldistributed chondrocytes at the border and the bottom of the defects. At 16 weeks postoperatively, 6 joints in the experimental group had smooth surface, and the defects were basically repaired by hyaline cartilage-like tissues. The newly-formed tissues integrated well with the surrounding area. Under the cartilage, the new bone formation was still active and some DBM particles could be seen. However, the defects in the control group were repaired by fibrous tissues. The result of histological scoring of the specimens at 16 weeks showed that a total of 6 aspects including formation of chondrocytes and integration with the surrounding cartilages were superior in the experimental group to those in the control group, and there were significant differences between the two groups (P < 0.05).

CONCLUSION

The biodegradable and injectable complex of HV-C/GP-DBM with good histocompatibility and non-toxic side effects can repair cartilage defects and is a promising biomaterial for cartilage defect repair.

Biocompatibility and manageability of a new fixable bone graft for the treatment of localized bone defects: preliminary study in a dog model

The present investigation was performed to compare the biocompatibility, safety, and manageability of a newly developed bone block and a deproteinized bovine bone block (Bio-Oss) for the treatment of localized bone defects in a dog model. Two male beagle dogs were used for this study. The mandibular premolars were extracted and two saddle-type defects were created bilaterally in the edentulous area. The defects were filled according to a randomized design with Bio-Oss bone block or with an equine hydroxyapatite plus collagen bone block (eHAC). Most control and test sites developed dehiscences during healing. After 4 weeks, the animals were euthanized and each hemimandible was prepared for histologic examination. No significant difference in terms of local tolerance was observed between test and control sites, and test and control sites showed similar histologic findings. However, a significant difference was noticed between the Bio-Oss block and the new bone block in terms of manageability.

Clinical and histologic evaluation of allogeneic bone matrix versus autogenous bone chips associated with titanium-reinforced e-PTFE membrane for vertical ridge augmentation: a prospective pilot study

PURPOSE

To compare clinically and histologically an allogeneic bone matrix to autogenous bone chips in the vertical ridge augmentation technique using titanium-reinforced e-PTFE membranes.

MATERIALS AND METHODS

The study protocol was designed to include patients with bilateral posterior mandibular partial edentulism. Patients were treated with a split-mouth design approach: each side was randomly assigned to the test group (titanium-reinforced e-PTFE membrane and allogeneic bone matrix) or to the control group (titanium-reinforced e-PTFE membrane and autogenous bone chips). Different clinical parameters including the amount of vertically regenerated bone (DSB) and biologic complications were recorded. Histomorphometric analysis and the bone-implant contact percentage were performed.

RESULTS

Five female patients were enrolled in the study. Ten edentulous sites were vertically augmented and 25 implants were inserted (13 test group, 12 control group) with a staged approach. In the test group no membrane was exposed. The mean bone regeneration was 4.70 mm (SD 0.48 mm). All 13 implants appeared clinically stable. In the control group, 1 membrane was exposed after 2 months. The mean crestal bone regeneration was 4.10 mm (SD 0.88 mm). All 12 implants were stable at the abutment connection. Nine biopsy specimens from the regenerated areas were evaluated. Vertical bone regeneration was evident in both groups since all the samples demonstrated trabecular bone with different degrees of maturation and mineralization in the regenerated area.

CONCLUSION

Within the limits of this study based on 5 patients, it appears that the behavior of the allogeneic bone matrix is similar to that of autogenous bone chips when used for vertical ridge augmentation by means of guided bone regeneration techniques. Both grafts demonstrated analogous histologic characteristics. Nevertheless, long-term clinical studies are needed to confirm these preliminary results.

Immediate versus early nonocclusal loading of dental implants placed with a flapless procedure in partially edentulous patients: preliminary results from a randomized controlled clinical trial

The aim of this randomized controlled clinical trial was to compare the efficacy of implants placed with a flapless procedure and restored immediately (test group) or early (6 weeks) (control group) in partially edentulous patients up to 1 year after loading. Both groups were nonocclusally loaded. Ten patients were included in each group. No patients dropped out and no failures were recorded. Two complications occurred in the early loading group, but both were resolved. It can be concluded that the use of a flapless technique for placing implants in conjunction with nonocclusal immediate loading in select patients can provide excellent clinical results. These preliminary findings should be confirmed by larger randomized clinical trials.

[Treatment of traumatic bone defect with graft material of allogenic cancellous combined with autologous red marrow]

OBJECTIVE

To study clinical effects of the graft material of allogenic cancellous combined with autologous red marrow in the treatment of traumatic bone defect.

METHODS

From February 2002 to April 2006, 38 patients of traumatic bone defect, 25 males and 13 females, aged 21-68 years old (38 on average), were treated with allogenic cancellous combined with autologous red marrow. Among them, there were 11 cases of bone nonunion caused by failure of internal fixation, 13 of serious comminuted fracture, 9 of bone defect caused by open fractures or bone infection, 5 of old fracture in need of graft. Of these fractures, there were 8 cases of shaft of humerus, 4 of intercondylar comminuted fracture of humerus, 8 of intercondylar comminuted fracture of femur, 5 of shaft of femur, 4 of open tibia fracture (Gustilo I, II type) and 9 of tibial plateau fracture. They included 17 cases of fresh fracture and 21 of old fracture. There were 23 cases of limitations of bone defect, and the range was 3 cm x 3 cm x 2 cm - 7 cm x 4 cm x 3 cm; and the range of the large bone defect was less than 3 cm in 15 cases. According to AO/ASIF classification, there were 5 cases of type B2, 10 of type B3, 16 of type C2 and 7 of type C3. The time from fresh fracture to operation was 5-17 days (8 days on average), and the time from old fracture to operation was 5-13 months (7.5 months on average). The amount of the allograft implantation was 20-50 g (28 g on average).

RESULTS

The wounds in all 38 cases obtained healing by first intention. All the patients were followed up for 8 months to 4 years (3.2 years on average). The X-ray films at reexamination showed that 36 patients had bone healing, with fresh fracture healing time of 2-6 months (4 months on average) and old fracture healing time of 3-10 months (7 months on average). The allogenic cancellous particles began to be fused with autogenous bone through creeping substitution 6-8 weeks after operation. One case, which had delayed infection, had bone union by removing internal fixation, placing irrigating tube and grafting after local stability. During the follow-up of 25 months, no relapse was found. Another case had nonunion because of plate loosening. According to the Mankin and Komender standard evaluation, there were 36 cases with satisfaction (94.7%) and 2 with dissatisfaction (5.3%).

CONCLUSION

The composite graft material of allogenic cancellous combined with autologous red marrow is safe and effective for repairing fractures and bone defect.

Guided bone regeneration using an allograft material: review and case presentations

Post extraction sites may have residual ridge deformities with insufficient bone present for future implant placement. This presents a challenge to the clinician attempting to obtain optimum results. To predictably augment these areas and obtain aesthetically pleasing results, bone grafting may be required. Guided bone regeneration with an allograft material is a predictable means by which to solve this challenge. This article describes three case presentations utilizing on allograft material for bone regeneration prior to implant placement.

Zirconia for teeth and implants: a case series

This case series reports on the use of nonsilica-based high-strength full ceramics for different prosthetic indications. Fifty-two consecutive patients received tooth- or implant-supported zirconia reconstructions during a 2-year period. The observation period for reexamination was 12 to 30 months. The most frequent indications were single crowns and short-span fixed partial dentures. A few implant superstructures were screw-retained, whereas all remaining restorations were cemented on natural teeth or zirconia implant abutments. Clinical examination included biologic (probing depths, bleeding on probing) and esthetic (Papilla Index) parameters, as well as technical complications. No implant was lost or caused any problems, but two teeth were lost after horizontal fracture. Overall, the periodontal parameters were favorable. Fractures of frameworks or implant abutments were not observed. Abutment-screw loosening occurred once for one premolar single crown. Furthermore, five implant crowns in the posterior region exhibited chipping of the porcelain veneering material. With regard to esthetics, no reconstructions were considered unacceptable, but three crowns were remade shortly after delivery. In this short-term study, it was observed that biologic, esthetic, and mechanical properties of zirconia were favorable, and the material could be used in various prosthetic indications on teeth or implants.

[Three-tunnels core decompression with implantation of bone marrow stromal cells (bMSCs) and decalcified bone matrix (DBM) for the treatment of early femoral head necrosis]

OBJECTIVE

To analyse retrospectively 3-tunnels core decompression with implantation of bone marrow stromal cells(bMSCs) and decalcified bone matrix (DBM) for treatment of femoral head necrosis in early stages, and to study its therapeutic results and indications.

METHODS

According to the University of Pennsyvania system of classification and staging,to treat the patients with 3-tunnels core decompression with implantation of bone marrow stromal cells (bMSCs) and decalcified bone matrix (DBM) for treatment of early femoral head necrosis. Among the total 87 patients (103 hips), the male was 71 (86 hips) and the female 16 (17 hips) with the average age of 47 years old. The average course of disease was 1.3 year. The effect was evaluated by the clinical symptoms, the Harris' scores and the manifestations of radiology before and after operation.

RESULTS

All the patients were followed up more than 2 years (average 26 months). The average Harris' scores increased from preoperation 47.3 to postoperation 74.0. The average rate of excellent and good results was 75.7%. The rate of excellent and good was 88% (22/25) in type I, 78.7% (37/47) in type II and 61.3% (19/31) in type III. No severe complications were observed.

CONCLUSION

Three-tunnels core decompression with implantation of bMSCs and DBM not only removal the focus of disease, but also use DBM the induction of bone and autologous hone marrow stem cells to differentiate the functions of the femoral head can be resumed loading structure, eliminate pain,improve joint function. It is an effective method for early femoral head necrosis.

Healing patterns of critical size bony defects in rat following bone graft

PURPOSE

The aim of the present study was to evaluate the healing patterns of critical size calvarial bony defects treated with different bone substitutes and to compare them to an autogenous graft and an ungrafted control group.

MATERIALS AND METHODS

Thirty-six Sprague-Dawley rats (200-230 g) were used. A periosteal flap was raised and an 8 mm defect was trephined. Rats were divided into six groups and treated as follows: group 1 was treated with a deproteinized bovine xenograft (XO), group 2 was treated with a bovine xenograft and covered with a resorbable membrane (XOCM), defects in group 3 were filled with a decalcified freeze-dried bone allograft (DFDBA), group 4 was treated with a composite bone substitute made of bovine xenograft and collagen (XOC), group 5 was filled with autogenous bone (AUTO), and group 6 was left untreated (control). The animals were euthanized at 2 months.

RESULTS

Mean bone formation was 2.97 +/- 1.82 mm2 in group 5 (AUTO) followed by 2.93 +/- 1.93 mm2 in group 3 (DFDBA) and 2.25 +/- 1.94 mm2 in group 4 (XOC). Groups 1, 2, and 6 (XO, XOCM, and control, respectively) were not significantly different (p > 0.05) with a mean bone formation of 1.97 +/- 1.64, 1.87 +/- 1.07, and 1.85 +/- 1.04 mm2, respectively.

CONCLUSIONS

This work confirmed the superiority of autogenous bone when it comes to bone grafting. Nevertheless, some bone substitutes can improve bone formation when compared to the control. New bone substitutes with growth factors to improve their abilities to induce bone formation should be experimented.

Simplified osteotome sinus augmentation technique with simultaneous implant placement: a clinical study

The aim of this study was to describe and evaluate a modified maxillary sinus floor augmentation technique: the simplified osteotome technique. The study consisted of 26 patients treated with 39 Brånemark implants (Nobel Biocare) placed using the simplified osteotome technique between September 1997 and November 2004 (87 months). Implant length ranged from 10 to 15 mm, while the loading time ranged from 5 to 74 months (mean: 35.2 months). The success rate was 97.4% according to Albrektsson's criteria. These preliminary data indicate that the simplified osteotome technique is effective and safe, though long-term, multicenter studies are still needed.

Three-dimensional alveolar bone reconstruction with a combination of recombinant human platelet-derived growth factor BB and guided bone regeneration: a case report

A report of a patient who presented with severe disfigurement of the maxillary left lateral incisor and canine area following oncologic surgery is presented. The bone defect extended 20 mm from the cervical line of adjacent teeth up to and including the nasal cavity. Treatment was performed with a 1:1 ratio of autogenous bone graft (harvested from the retromolar region) and deproteinized bovine bone particles. The composite graft was hydrolyzed with recombinant human platelet-derived growth factor BB and covered with a titanium-reinforced nonresorbable membrane. Second-stage surgery was performed at 6 months, at which point the membrane was removed and two titanium dental implants were successfully placed. The elapsed time from initial surgery to definitive prosthesis placement was 14 months.

Histomorphometric comparison of a biphasic bone ceramic to anorganic bovine bone for sinus augmentation: 6- to 8-month postsurgical assessment of vital bone formation. A pilot study

This blinded, randomized, controlled pilot investigation is the first to histomorphometrically compare vital bone formation following bilateral sinus grafting with a biphasic calcium phosphate (BCP) (Straumann Bone Ceramic) to an anorganic bovine bone matrix (ABBM) (Bio-Oss) 6 to 8 months following graft placement. Twelve patients were selected. Following elevation of the lateral sinus walls, one material was placed in the right sinus and the other material was placed in the left sinus, as determined by randomization. Six to 8 months after grafting (with the same time frame used for each patient), a trephine core was taken from the grafted area and sent for histomorphometric analysis. Cores were obtained from 21 healed sinuses in 12 patients. Nine patients provided bilateral cores. Histomorphometric analysis of 10 BCP cores and 11 ABBM cores revealed an average vital bone content of 28.35% and 22.27%, respectively. The average percentage of residual graft particles was 28.4% in the BCP cores and 26.0% in the ABBM cores. The difference in vital bone formation was not significantly different (n = 9 patients, paired t test) between bilateral sinuses treated with the BCP and those treated with the ABBM. Histologically, both materials appeared to be osteoconductive and support new bone formation. Future studies are needed to confirm the ability of this regenerated bone to support dental implant maintenance over time.

Efficacy of guided tissue regeneration in the management of through-and-through lesions following surgical endodontics: a preliminary study

The purpose of this prospective study was to assess the outcome of periradicular surgery with or without guided tissue regeneration (GTR) for the treatment of through-and-through lesions. Thirty-four teeth were included according to specific selection criteria. In the test group (using GTR), after root-end filling, the defects were filled with anorganic bovine bone and covered with a resorbable collagen membrane. Healing was assessed according to specific criteria and graded as successful, doubtful, or failed. In the control group, neither grafts nor membranes were used. After 1 year, 31 teeth were evaluated. Of these, 22 (71%) healed successfully, 6 (19%) showed doubtful healing, and 2 were recorded as failures. The outcomes of the defects treated with GTR (88% successful) were significantly better than those of the control group (57% successful). The present study showed that the use of GTR associated with anorganic bovine bone in the treatment of through-and-through lesions may positively affect the healing process.

Sinus bone grafting procedures using ultrasonic bone surgery: 5-year experience

Ultrasonic bone surgery was recently introduced as an osteotomic technique; however, documentation is scarce. This article reports on the application of ultrasonic bone surgery for 53 bone-augmentation procedures in the posterior maxilla in 34 patients over 5 years. The initial residual bone height under the sinus varied between 1 and 9 mm (mean: 3.7 mm). Distribution according to residual bone height classes was 7.7% for Class B, 39.3% for Class C, and 53.0% for Class D. The procedures included bony window opening of the sinus, cortical and cancellous bone harvesting, and activation of the sinus wall. During the sinus approach, 2 of 53 membranes (3.8%) were perforated and covered with a membrane made of platelet-poor plasma. Bone grafting was carried out with autologous bone at 22 implant sites (18.8%), with a mixture of autologous bone and anorganic bovine bone mineral (Bio-Oss) at 29 sites (24.8%), and with Bio-Oss alone at 66 sites (56.4%). The perforated membranes healed uneventfully. At second-stage surgery, four implants failed. The survival rate of the 117 placed implants was 96.6%. No implant failed after loading. Performing the sinus grafting procedure with ultrasonic bone surgery limited the occurrence of membrane perforation; by changing the tips, all surgical steps were performed safely and comfortably.

Regenerative therapy of deep peri-implant infrabony defects after CO2 laser implant surface decontamination

The treatment of a peri-implant infrabony defect is difficult because of contamination of the implant surface and adjacent tissues. This case series addresses the ability of a carbon dioxide (CO2) laser to decontaminate failing implants in 15 patients. Clinical and radiologic data are presented with regard to using the laser in combination with bone grafting and a barrier. Augmentation with autogenous bone grafting material (n = 10) or a xenogenic bone grafting material (BioOss) (n = 9) was used, and bone grafts were covered with a collagen membrane. Clinical and radiologic parameters were evaluated postoperatively. After an observation period of 27 months (+/- 17.83), almost complete bone fill in the peri-implant defect was accomplished. These preliminary clinical and radiologic findings suggest that decontamination of the implant surfaces with the CO2 laser in combination with augmentative techniques can be an effective treatment method for peri-implantitis.

Healing of critical-size cranial defects in guinea pigs using a bovine bone-derived resorbable membrane

PURPOSE

To investigate the healing of critical-size cranial bone defects (9-mm-diameter) in guinea pigs treated with a bovine bone-derived resorbable membrane.

MATERIALS AND METHODS

A sample of 42 guinea pigs was divided into test (n = 20), control (n = 20), and standard (n = 2) groups. A full-thickness trephine defect was made in the fronto-parietal bone of each animal. In the test group, the internal and external openings of the defect were each closed with a separate membrane, and the space between them was filled with blood clot and a central spacer. In the control group, the defect was filled only with the blood clot and spacer. At 1, 3, 6, and 9 months later, the calvarias (5 per period) for both the test and control groups were collected, fixed, radiographed, and histologically processed. The standard-group animals were sacrificed immediately after surgery and used to determine the initial size of defect radiographically. The areas of defects in the radiographs were measured with image-analysis software and were compared between groups and periods by multiple regression analysis with the Bonferroni correction.

RESULTS

At 1 and 3 months, newly formed woven bone was histologically observed in both test and control groups. Radiographically, this new bone occupied an average of 32% of the defect area at 1 month and 60% at 3 months in the test group. In the control group, 21% of the defect was filled at 1 month and 39% at 3 months. However, the differences between treatments were not statistically significant (P > .05). At 6 and 9 months, a significant increase in newly formed lamellar bone was seen histologically in both groups. Radiographically, for the test group, the new bone occupied an average of 82% of the defect area at 6 months and 96% at 9 months. For the control group, new bone composed an average of 45% of the defect area at 6 months and 40% at 9 months. The differences between the test and control groups were statistically significant at 6 and 9 months (P < .05). Complete or almost complete filling of the defect was observed in several cases.

CONCLUSION

It was concluded that the bovine bone-derived membrane is highly biocompatible and is able to promote good healing of critical-size defects in calvaria of guinea pig.

Five-year clinical and histologic results following treatment of human intrabony defects with an enamel matrix derivative combined with a natural bone mineral

Treatment of intrabony periodontal defects with a combination of an enamel matrix derivative (EMD) and a natural bone mineral (NBM) has been demonstrated to significantly improve clinical parameters such as probing depth (PD) and clinical attachment level (CAL). However, long-term clinical and histologic data on treatment with this approach are limited. The aim of the present study was to present the 5-year clinical and histologic results following treatment of intrabony defects with a combination of EMD + NBM. Eleven healthy patients, all with advanced chronic periodontitis and one deep intrabony defect each, were consecutively treated with a combination of EMD + NBM. PD, recession of the gingival margin (GR), and CAL were measured just before and at 1 and 5 years after treatment. The primary outcome variable was CAL. No adverse healing responses were observed. Mean PD, GR, and CAL were significantly reduced at 1 year and at 5 years versus baseline values. Histologic analysis of a mandibular second molar, extracted 5 years after treatment with EMD + NBM, demonstrated bone formation around the NBM particles. Regenerative surgery with the combination of EMD + NBM may result in bone formation, and the obtained clinical results can be maintained over a period of 5 years.

Experimental application of a biomaterial in bifocal transport osteogenesis for craniofacial reconstruction

PURPOSE

Bifocal transport osteogenesis is an alternative technique of callus distraction, in which movement of a transport segment results in the formation of new bone in order to close a continuity defect. The aim of this experimental pilot study was to replace a bone graft by a biomaterial as a transport segment.

MATERIAL AND METHODS

Critical size defects of the calvaria in four adult sheep were treated with transport segments consisting either of an autogenous free bone graft of the calvaria (n=2) or of the biomaterial (deproteinized bovine cancellous bone; n=2). Latency period was 5 days; the rate of distraction was 1mm per day and was planned for 40 days. The consolidation period was 28 days. Specimens were investigated by conventional radiography, CT-scans and histologically, including immunofluorescence.

RESULTS

In both groups, transport osteogenesis resulted in a "de novo" formation of bone, indicating that this biomaterial may contribute successfully to bone formation in bifocal transport osteogenesis. However, volume and thickness of the newly formed bone at the defect site were smaller when using the biomaterial than when using autogenous bone grafts.

CONCLUSION

The application of a biomaterial as transport segments in bifocal transport osteogenesis in cranial critical size defects resulted in the formation of new bone thus excluding bone graft donor site morbidity.