Effect of porous xenographic bone graft with collagen barrier membrane on periodontal regeneration

The purpose of this study was to investigate the effect of porous xenographic bone graft (Bio-Oss) with a collagen barrier membrane (Bio-Gide) on formation of new cementum and new bone in experimental intrabony defects of dogs. The intrabony defects were treated by either guided tissue regeneration with the collagen membrane (control group) or the collagen membrane with the porous bone mineral graft (experimental group). After 8 weeks, the animals were sacrificed and the tissues were histologically examined. New cementum with inserting collagen fibers was observed on the exposed surfaces in both groups. The amount of nevv bone was significantly greater in the group using the bone graft with the membrane than in the control group. The use of the collagen barrier membrane in combination with the porous bone graft material may enhance new bone and cementum formation.

Platelet-rich plasma and bovine porous bone mineral combined with guided tissue regeneration in the treatment of intrabony defects in humans

BACKGROUND

A combination of platelet-rich plasma (PRP), bovine porous bone mineral (BPBM) and guided tissue regeneration (GTR) has been shown to be effective in promoting clinical signs of periodontal regeneration in intrabony defects. As an initial attempt to clarify the role played by each of the three treatment components, this study was performed to compare the clinical effectiveness of two regenerative techniques for intrabony defects in humans: a combination of PRP/BPBM/GTR vs. GTR.

MATERIAL AND METHODS

Eighteen patients participated in the study. Using a split-mouth design, interproximal bony defects were surgically treated with either an absorbable membrane made of polylactic acid for GTR or a combination of PRP/BPBM/GTR. Changes in pocket depth, attachment level and defect fill as revealed by 6-month reentry surgeries were evaluated.

RESULTS

Both treatment modalities resulted in significant pocket depth reduction and clinical attachment gain as compared to baseline values. Pocket depth reduction was 4.98 +/- 0.96 mm on buccal and 4.93 +/- 0.92 mm on lingual sites of the PRP/BPBM/GTR group and 3.62 +/- 0.81 mm on buccal and 3.54 +/- 0.88 mm on lingual sites of the GTR group. The gain in clinical attachment observed was 4.37 +/- 1.31 mm on buccal and 4.28 +/- 1.33 mm on lingual sites of the PRP/BPBM/GTR group and 2.62 +/- 1.23 mm on buccal and 2.44 +/- 1.21 mm on lingual sites of the GTR group. The amount of defect fill observed was 4.78 +/- 1.26 mm on buccal and 4.66 +/- 1.32 mm on lingual sites of the PRP/BPBM/GTR group and 2.31 +/- 0.76 mm on buccal and 2.26 +/- 0.81 mm on lingual sites of the GTR group. All differences between the two groups were statistically significant in favor of the PRP/BPBM/GTR group.

CONCLUSIONS

The results of this study suggest that PRP and BPBM provide an added regenerative effect to GTR in promoting the clinical resolution of intrabony defects on patients with severe periodontitis.

Freeze-dried homogeneous and heterogeneous bone for sinus augmentation in sheep. Part I: histological findings

Freeze-dried bone has been reported to possess an osteogenetic potential, i.e. to be osteo-inductive or osteoconductive depending on the grafted site. In this animal study homogeneous demineralized freeze-dried bone from the sheep (s-DFDB) and heterogeneous human demineralized freeze-dried bone (h-DFDB) used for single-stage sinus elevation were examined for their potential to improve bone-to-implant bonding. In 72 sinuses of 36 adult female mountain sheep Schneider's membrane was elevated from the local bone through an extra-oral approach and two cylindrical plasma-flame sprayed titanium implants were inserted in the lateral wall of each sinus. At the same time 18 sinuses were reinforced with s-DFDB, another 18 with h-DFDB and yet another 18 with autogenous cancellous bone from the iliac crest. In 18 animals the subantral space remained ungrafted. At each follow-up date, i.e. at 12, 16 and 26 weeks, 12 animals were re-examined and one randomly selected implant from each sinus was analyzed histologically and histomorphometrically. With both s-DFDB and h-DFDB extensive fragmentation and disintegration were seen side by side with sporadic areas of remineralization. These were mainly located in the vicinity of the local host bone and coalesced over time to be ultimately replaced and consolidated by woven bone. But most of the h-DFDB/s-DFDB particles continued to be embedded in abundant collagenous connective tissue and were surrounded by mononucleated and multinucleated giant cells, ultimately causing extensive resorption. The mean bone-to-implant contact length was 16.4% of the implant surface for s-DFDB, 16.9% for h-DFDB, 32.8% for autogenous bone and 22.2% in ungrafted controls. In the autogenous bone group the mean bone-to-implant contact length progressively increased with increasing contact time. In the control group, by contrast, the mean bone-to-implant contact length initially increased in the first two follow-up periods, but dropped again at 26 weeks. Both in the h-DFDB and the s-DFDB group the percent bone contact area was lower at 16 weeks than at 12 weeks but increased again by 26 weeks. In apical implant sections, s-DFDB produced significantly less bone-to-implant contact than autogenous cancellous bone from the iliac crest. In basal implant sections, both DFDB-grafted groups did significantly less well than the two control groups. The results of this experimental study showed that DFDB homografts and heterografts cannot be recommended alone instead of cancellous autografts from the iliac crest for augmenting the maxillary sinus in single-stage sinus elevations. Longer follow-up times than in the present study may perhaps show better results at the bone-implant interface.

Two uncommon uses of Bio-Oss for GTR and ridge augmentation following extractions: two case reports

Bio-Oss is natural bovine bone mineral, which has the property of bone conduction. It is recommended to be used in two- or three-walled bony defects with an ample supply of pleuripotential cells. Two cases are reported. The first was an intentional replantation, because of previous trauma, of a hopeless tooth affected with severe periodontitis. The tooth was replanted after complete elimination of granulation tissue. Bio-Oss, together with a guided tissue regeneration (GTR) membrane, was used to enhance periodontal regeneration. After 2 years of follow-up, the replanted tooth was quite stable. In the second case, Bio-Oss, together with bone taken from the retromolar area, was used in a sinus lift grafting procedure after the removal of two supernumerary teeth from the floor of the maxillary sinus. Four months after grafting, an orthodontic treatment was applied to move the two adjacent teeth through the grafted site and align them in the proper position. The clinical results of the two cases were satisfactory.

In vitro osteoclast resorption of bone substitute biomaterials used for implant site augmentation: a pilot study

PURPOSE

This observational study examined the resorptive behavior of normal neonatal rabbit osteoclasts grown on slices of bovine cortical bone as compared to samples of commercially available bone substitute biomaterials. It also examined the surface characteristics of these materials.

MATERIALS AND METHODS

The 11 materials tested fell into 3 groups: (1) bone-derived, including freeze-dried human rib block, human demineralized freeze-dried bone, and deproteinated bovine bone; (2) synthetic hydroxyapatites (HA); and (3) synthetic non-HA, including coated methacrylates and coated silica glass. After 4 days in culture, 1 group of samples of each material underwent scanning electron microscopy (SEM) to evaluate resorptive pitting versus controls, while another group underwent tartrate-resistant acid phosphatase staining and light microscopy to examine osteoclast numbers and morphology. The 2 bovine-derived HA materials also underwent immunohistochemical staining and surface chemistry analysis.

RESULTS

While most of these materials supported osteoclast attachment, some spreading, and survival in culture, only the bone-derived materials, with the exception of sintered deproteinated bovine bone, showed large scalloped-edged resorption pits with trails and exposed collagen when examined by SEM, although not to the same extent as unprocessed natural bone material. The HA materials and the sintered deproteinated bovine bone showed evidence of etching with smaller pits but no evidence of resorptive trail formation. The non-HA materials showed no evidence of pit formation or trails. Under immunohistochemical staining, Bio-Oss appeared to be positive for type I collagen after osteoclast activity on its surface, while Osteograf/N showed no positive staining. Surface chemistry analysis revealed nitrogen present in Bio-Oss specimens (0.17% to 0.47%), while there was no nitrogen detected in the Osteograf/N (0.00%); the percent nitrogen observed in normal bovine bone controls was 6.01% to 9.25%.

DISCUSSION

The bone-derived materials supported osteoclast activity on the material surface in a way that facilitated formation of the more complex resorption pits in vitro. Assuming the rate of pit formation observed in vitro mimics that observed in vivo, the quantity and type of osteoclastic remodeling seen on non-bone-derived materials--and perhaps sintered bone-derived materials--would be extremely slow to negligible. Physiologic removal of non-bone-derived bone substitutes in vivo may occur by methods other than osteoclast resorption.

CONCLUSIONS

Allogenous and xenogenous bone-derived materials that undergo delayed physiologic resorption may be more appropriately used with a staged surgical approach when used in sites intended to support osseointegrated dental implants. The combination of collagen staining and the presence of nitrogen suggest that there may be residual protein in Bio-Oss.

Bone and suture regeneration in calvarial defects by e-PTFE-membranes and demineralized bone matrix and the impact on calvarial growth: an experimental study in the rat

The aim of this study was to evaluate the effect of: guided tissue regeneration (GTR) alone, implantation of demineralized bone matrix (DBM) alone, and of the combined treatment on the healing of craniectomy defects involving the sagittal cranial suture, and to examine subsequent calvarial growth. Sixty four-week-old rats were used in the study. These animals were randomly assigned to five groups (A-E) of 12 animals. In four groups (A-D), a calvarial defect (5.0 mm) involving the sagittal suture was produced in each animal. Group A: The defect was left untreated. Group B: DBM was implanted into the defect. Group C: The cerebral and the galeal aspect of the defect was covered with an e-PTFE membrane. Group D: The defect was treated with the double membrane technique combined with implantation of DBM. Group E: The animals were sham-operated, no defect was created. In all groups, two gutta-percha points were placed to indicate the lateral borders of the parietal bones. Histological analysis 4 months following surgery showed that the untreated cranial defects (A) had healed with fibrous connective tissue in the midportion of the defect. The DBM grafted defects (B) healed either completely with bone containing DBM particles or partially with bone and connective tissue. The defects (D) treated with DBM combined with GTR healed completely with bone, while the defects (C) treated with membranes alone healed with bone but a suture-like tissue similar to the normal sagittal suture of the sham-operated controls (E) was always present in the midportion of the defect. Cephalometric radiography demonstrated that the membrane-treated (C) and the sham-operated animals (E) exhibited similar coronal growth of the cranial vault following treatment. Craniometric measurements on chemically defleshed specimens showed that sham-operated and membrane-treated animals presented significantly more biparietal width than the animals treated with DBM alone or DBM combined with GTR (P < 0.05). The results demonstrated that predictable osseous healing including the formation of a sagittal suture can be accomplished in craniectomy defects by GTR, and undisturbed cranial growth reestablished. The treatment of the defects with DBM alone or DBM combined with GTR resulted in craniosynostosis and reduced cranial growth.

The effect of a fibrin glue on the integration of Bio-Oss with bone tissue. A experimental study in labrador dogs

BACKGROUND

Bio-Oss is a deproteinized bovine mineral used in bone augmentation procedures. The particles are often mixed with a protein product (Tisseel) to form a mouldable graft material.

AIM

The aim of the present experiment was to study the healing of self-contained bone defects after the placement of Bio-Oss particles alone or mixed with Tisseel in cylindrical defects in the edentulous mandibular ridge of dogs.

MATERIAL AND METHODS

In 4 labrador dogs, the 2nd, 3rd and 4th mandibular premolars were extracted bilaterally. 3 months later, 3 cylindrical bone defects, 4 mm in diameter and 8 mm in depth, were produced in the right side of the mandible. Following a crestal incision, full thickness flaps were raised and the bone defects were prepared with a trephine drill. The defects were filled with Bio-Oss (Geistlich Biomaterials, Wolhuser, Switzerland) particles alone or mixed with Tisseel (Immuno AG, Vienna, Austria), or left "untreated". A collagen membrane (Bio-Gide, Geistlich Biomaterials, Wolhuser, Switzerland) was placed to cover all defects and the flaps were sutured. 2 months later, the defect preparation and grafting procedures were repeated in the left side of the mandible. After another month, the animals were sacrificed and biopsies obtained from the defect sites.

RESULTS

Bio-Oss-treated defects revealed a higher percentage of contact between graft particles and bone tissue than defects treated with Bio-Oss+ Tisseel (15% and 30% at 1 and 3 months versus 0.4% and 8%, respectively). Further, the volume of connective tissue in the Bio-Oss treated defects decreased from the 1 to the 3 month interval (from 44% to 30%). This soft tissue was replaced with newly formed bone. In the Bio-Oss+ Tisseel treated defects, however, the proportion of connective tissue remained unchanged between 1 and 3 months.

CONCLUSION

The adjunct of Tisseel may jeopardize the integration of Bio-Oss particles with bone tissue.

Bone grafting alternatives in spinal surgery

BACKGROUND CONTEXT

Bone grafting is used to augment bone healing and provide stability after spinal surgery. Autologous bone graft is limited in quantity and unfortunately associated with increased surgical time and donor-site morbidity. Alternatives to bone grafting in spinal surgery include the use of allografts, osteoinductive growth factors such as bone morphogenetic proteins and various synthetic osteoconductive carriers.

PURPOSE

Recent research has provided insight into methods that may modulate the bone healing process at the cellular level in addition to reversing the effects of symptomatic disc degeneration, which is a potentially disabling condition, managed frequently with various fusion procedures. With many adjuncts and alternatives available for use in spinal surgery, a concise review of the current bone grafting alternatives in spinal surgery is necessary.

STUDY DESIGN/SETTING

A systematic review of the contemporary English literature on bone grafting in spinal surgery, including abstract information presented at national meetings.

METHODS

Bone grafting alternatives were reviewed as to their efficacy in extending or replacing autologous bone graft sources in spinal applications.

RESULTS

Alternatives to autologous bone graft include allograft bone, demineralized bone matrix, recombinant growth factors and synthetic implants. Each of these alternatives could possibly be combined with autologous bone marrow or various growth factors. Although none of the presently available substitutes provides all three of the fundamental properties of autograft bone (osteogenicity, osteoconductivity and osteoinductivity), there are a number of situations in which they have proven clinically useful.

CONCLUSIONS

Alternatives to autogenous bone grafting find their greatest appeal when autograft bone is limited in supply or when acceptable rates of fusion may be achieved with these substitutes (or extenders) despite the absence of one or more of the properties of autologous bone graft. In these clinical situations, the morbidity of autograft harvest is reasonably avoided. Future research may discover that combinations of materials may cumulatively result in the expression of osteogenesis, osteoinductivity and osteoconductivity found in autogenous sources.

Human segmental mandibular defects treated with naturally derived bone morphogenetic proteins

Bone induction with extracted and partially purified, naturally derived bone morphogenetic proteins (BMPs) has been demonstrated repeatedly in heterotopic and orthotopic sites of non-human primates. This spawned the investigation of bone regeneration in mandibular defects of human patients with naturally derived BMPs and was compared with osteogenesis in patients treated with autologous bone grafts (ABGs). The osteogenic device (OD) was formulated as a combination of human demineralized bone matrix as delivery system reconstituted with naturally derived BMPs. BMPs were extracted from bovine bone with chaotropic agents and purified by sequential chromatography. Thirteen patients with segmental mandibular defects were enrolled in the trial, 6 of whom received the OD and 7 the ABGs. Defects were reconstructed with a preformed titanium mesh. The OD was combined with sterile saline and applied to the defects as a paste. Autologous bone from the iliac crest was prepared as a cortico-cancellous bone graft and loaded into the titanium mesh. Patients were followed-up clinically and radiographically at 1 and 6 weeks, 3, 6, and 12-month post-implantation. A trephine biopsy of the implants was performed at 3 months post-implantation and the specimens examined on serial undecalcified sections. Histological examination showed that the OD induced bone in 2 of 6 patients treated. Histological examination of successful implanted OD exhibited mineralized bone trabeculae with copious osteoid seams lined by contiguous osteoblasts. Bone deposition directly onto non-vital matrix provided unequivocal evidence of osteoinduction. Of the 7 patients grafted with ABGs, 5 had histological evidence of osteogenesis. Morphometric analysis of the histological sections showed that, when successful, OD-treated defects had highly active osteogenesis compared with ABGs. Whilst this trial provides valuable insights for the use of BMPs in mandibular reconstruction further work is required to produce an OD that will perform reliably in clinical contexts.

A clinical comparison of a bovine-derived xenograft used alone and in combination with enamel matrix derivative for the treatment of periodontal osseous defects in humans

BACKGROUND

Enamel matrix protein derivative (EMD) and particulate anorganic cancellous bovine-derived bone xenograft (BDX) have both shown favorable clinical results in reducing intrabony periodontal defects as compared to open flap debridement alone. These materials have shown results comparable to those obtained with guided tissue regeneration. The primary aim of the present study was to evaluate the effectiveness of EMD combined with BDX as compared to BDX alone, with a secondary aim to compare the treatment outcomes of the 2 modalities.

METHODS

Seventeen patients with paired intrabony defects and probing depths measuring > or = 5 mm who were being treated for chronic periodontitis were selected for this controlled, blinded, split-mouth study. Following non-surgical periodontal therapy, sites were randomly selected to receive either a combination of EMD and BDX (test group) or BDX alone (positive control group). Baseline and 6-month surgical reentry measurements were taken by a calibrated examiner blinded to the treatment. A paired Student t test was utilized to evaluate differences between baseline and post-treatment and between the treatment groups.

RESULTS

Favorable clinical outcomes for both hard and soft tissue measurements were achieved for both treatment groups when compared to baseline (P < 0.001). There was no statistically significant difference for any of the measured clinical parameters. Probing depth reduction for the test group and control group was 4.2 +/- 1.1 mm and 3.9 +/- 1.3 mm, respectively (P > 0.8). Mean gain in clinical attachment levels for the test and control groups was 3.8 +/- 0.9 mm and 3.7 +/- 1.5 mm, respectively (P > 0.6). Hard tissue measurements obtained at surgical reentry were used to calculate the bone fill (BF) and percent bone fill (%BF). The BF was 3.2 +/- 1.4 mm and 3.0 +/- 1.2 mm (P > 0.6), and the %BF was 63.3 +/- 16.3% and 67.0 +/- 19.0% (P > 0.4) for the EMD + BDX and BDX groups, respectively.

CONCLUSIONS

In summary, both the particulate anorganic cancellous bovine-derived bone xenograft used alone and in combination with enamel matrix derivative are effective for the treatment of human intrabony periodontal lesions.

Orthodontic movement into bone defects augmented with bovine bone mineral and fibrin sealer: a reentry case report

Periodontal disease can lead to migration of anterior teeth with the presence of infrabony defects. This creates the opportunity for treating such patients with a combined orthodontic-periodontic treatment. In the presented clinical case, an adult periodontal patient with extrusion of the maxillary central incisors and an infrabony defect on their lingual aspects was treated. During the surgical procedure, the bone defects were augmented with a combination of porous bovine bone mineral (Bio-Oss) and a fibrin-fibronectin sealing system (Tissucol). Ten days after surgery, the active orthodontic treatment started, and the teeth were intruded and realigned, moving the roots into the defects. After 6 months, the orthodontic appliances were removed and the teeth were retained by means of a resin-bonded splint. At this time, reduction in probing pocket depth and gingival recession was detected. Twelve months after the initial surgery, a reentry procedure was performed, showing complete filling of the predisposing defects with the presence of bone-like hard tissue. These clinical results suggest that teeth can be successfully moved and intruded into bone defects previously augmented with bovine bone substitute and fibrin glue. During the orthodontic treatment, this combined augmentation material was able to be replaced by bone-like hard tissue. At the end of the therapy, an improvement in esthetics and periodontal health status was registered.

Clinical comparison of an enamel matrix derivative used alone or in combination with a bovine-derived xenograft for the treatment of periodontal osseous defects in humans

BACKGROUND

The combination of bone replacement graft materials has been suggested for the treatment of periodontal osseous defects. The purpose of this study was to evaluate the effectiveness of enamel matrix derivative (EMD) combined with a bovine-derived xenograft (BDX) as compared to EMD alone in the treatment of intraosseous defects in patients with moderate to advanced periodontitis.

METHODS

Sixteen adult patients with at least 2 intrabony defects were entered in this split-mouth design study. Defects were treated with EMD alone or EMD + BDX. Reentries were performed 6 to 8 months after initial surgery. The following soft and hard tissue measurements were recorded prior to initial surgery and at reentry: probing depth (PD), gingival margin location, clinical attachment level (CAL), depth of defect, and crestal bone level. Statistical analyses were performed to determine changes in PD, CAL, fill of osseous defect, and crestal resorption. Percentages of bone fill (%BF) and defect resolution (%DR) were also calculated.

RESULTS

The most significant results were that gingival recession was greater for the group treated with EMD alone (0.8 +/- 0.8 mm) compared to EMD + BDX (0.3 +/- 0.6 mm) (P = 0.04) and bone fill was greater for EMD + BDX (4.0 +/- 0.8 mm) compared to EMD alone (3.1 +/- 1.0 mm) (P = 0.02). The measures for PD reduction, attachment level gain, crestal resorption, %BF, and %DR did not present a statistically significant difference (P > 0.10).

CONCLUSIONS

This study evaluated the performance of EMD + BDX and EMD alone. The results demonstrated that a significant improvement in clinical parameters was observed. When comparing both modalities, a statistically significant difference was only found for gingival recession and bone fill, yielding a more favorable outcome towards the combined approach.

Histomorphometrical analysis of bone formed after maxillary sinus floor augmentation by grafting with a combination of autogenous bone and demineralized freeze-dried bone allograft or hydroxyapatite

BACKGROUND

Maxillary sinus floor augmentation procedures are currently the treatment of choice when the alveolar crest of the posterior maxilla is insufficient for dental implant anchorage. This procedure aims to obtain enough bone with biomaterial association with the autogenous bone graft to create volume and allow osteoconduction. The objective of this study was to histologically and histometrically evaluate the bone formed after maxillary sinus floor augmentation by grafting with a combination of autogenous bone, from the symphyseal area mixed with DFDBA or hydroxyapatite.

METHODS

Ten biopsies were taken from 10 patients 10 months after sinus floor augmentation using a combination of 50% autogenous bone plus 50% demineralized freeze-dried bone allograft (DFDBA group) or 50% autogenous bone plus 50% hydroxyapatite (HA group). Routine histological processing and staining with hematoxylin and eosin and Masson's trichrome were performed.

RESULTS

The histomorphometrical analysis indicated good regenerative results in both groups for the bone tissue mean in the grafted area (50.46+/-16.29% for the DFDBA group and 46.79+/-8.56% for the HA group). Histological evaluation revealed the presence of mature bone with compact and cancellous areas in both groups. The inflammatory infiltrate was on average nonsignificant and of mononuclear prevalence. Some biopsies showed blocks of the biomaterial in the medullary spaces close to the bone wall, with absence of osteogenic activity.

CONCLUSIONS

The results indicated that both DFDBA and HA associated with an autogenous bone graft were biocompatible and promoted osteoconduction, acting as a matrix for bone formation. However, both materials were still present after 10 months.

The modified trephine/osteotome sinus augmentation technique: technical considerations and discussion of indications

A technique is presented, which uses trephines of various external diameters followed by an osteotome to implode a core of maxillary posterior alveolar bone before placement of regenerative materials, in anticipation of subsequent implant placement. A mathematical formula is presented, which relates the depth of core displacement to the apico-occlusal dimension of alveolar bone coronal to the floor of the sinus presurgically. Seventy-one sites have been treated. All sites exhibited sufficient regeneration for implant placement. Two of the sites required additional augmentation at the time of implant placement. Fifty-one of the implants have been restored and are in function for up to 3 years. All are functioning successfully, as defined by the Albrektsson criteria. The technique and its indications and contraindications are described in detail.

Deproteinized bovine bone used as an adjunct to guided bone augmentation: an experimental study in the rat

BACKGROUND

Promising results have been reported following treatment of periodontal and peri-implant bone defects with deproteinized bovine bone grafts, but their influence on bone formation has not been clarified.

PURPOSE

The goal of this study was to examine whether implantation of deproteinized bovine bone (Bio-Oss, Geistlich AG, Wolhusen, Switzerland) influences bone formation when used as an adjunct to guided bone augmentation (GBA).

MATERIALS AND METHODS

A rigid, hemispherical, Teflon capsule was loosely packed with a standardized quantity of Bio-Oss and placed with its open part facing the lateral surface of the mandibular ramus (test) in 30 rats. At the contralateral side of the jaw, an empty capsule was placed (control). Groups of 10 animals were sacrificed after 1, 2, and 4 months. The volumes of the space created by the capsule and of the (1) newly formed bone, (2) remaining Bio-Oss particles, (3) soft connective tissue, and (4) acellular space in the capsule were estimated by a point-counting technique in three or four histologic sections, taken by uniformly random sampling.

RESULTS

Bone formation at 1 month was limited in both tests and controls. After 2 months, the mean volume of the newly formed bone occupied 9.0% of the space created by the capsule in the test specimens compared with 23.8% in the control specimens (p < .01). After 4 months, the respective figures were 11.6% (tests) versus 38.7% (controls) (p < .01).

CONCLUSION

It can be concluded that Bio-Oss, used as an adjunct to GBA, interferes with bone formation.

Comparison of platelet-rich plasma, bovine porous bone mineral, and guided tissue regeneration versus platelet-rich plasma and bovine porous bone mineral in the treatment of intrabony defects: a reentry study

BACKGROUND

A combination of platelet-rich plasma (PRP), bovine porous bone mineral (BPBM), and guided tissue regeneration (GTR) has been shown to be effective in promoting reduction in probing depth, gain in clinical attachment, and defect fill in intrabony periodontal lesions. The individual role played by PRP, BPBM, and GTR in this combined therapy is unclear and needs to be elucidated. The purpose of this study was to compare the clinical effectiveness of 2 regenerative techniques for intrabony defects in humans: a combination of PRP/BPBM/GTR versus a combination of PRP/BPBM.

METHODS

Twenty-one patients participated in the study. Using a split-mouth design, interproximal bony defects were surgically treated with either a combination of PRP/BPBM/GTR or PRP/BPBM. The primary outcomes of the study included changes in probing depth, attachment level, and defect fill as revealed by reentry surgeries at 6 months post-treatment.

RESULTS

At 6 months postoperatively, clinical examination of the treated defects revealed that both treatment modalities resulted in significant probing depth reduction and clinical attachment gain compared to baseline values. Probing depth improvement was 3.98 +/- 1.02 mm on buccal and 3.94 +/- 0.94 mm on lingual sites for the PRP/BPBM group and 4.19 +/- 0.88 mm on buccal and 4.21 +/- 0.92 mm on lingual sites for the PRP/BPBM/GTR group. Gain in clinical attachment was 3.78 +/- 0.72 mm on buccal and 3.84 +/- 0.76 mm on lingual sites for the PRP/BPBM group and 4.12 +/- 0.78 mm on buccal and 4.16 +/- 0.83 mm on lingual sites for the PRP/BPBM/GTR group. Reentry surgeries revealed similar defect fill for both treatment groups (PRP/BPBM group: 4.82 +/- 1.34 mm on buccal and 4.74 +/- 1.30 mm on lingual sites; PRP/BPBM/GTR group: 4.96 +/- 1.28 mm on buccal and 4.78 +/- 1.32 mm on lingual sites). None of the differences between the 2 treatment groups was statistically significant.

CONCLUSIONS

The results of this study show that both combinations of PRP/BPBM/GTR and PRP/BPBM are effective in the treatment of intrabony defects present in patients with advanced chronic periodontitis. The results also suggest that GTR adds no clinical benefit to PRP/BPBM. Further studies are necessary to assess the individual role played by PRP and BPBM in the clinical outcome achieved with their combination.

Closure of critical sized defects with allogenic and alloplastic bone substitutes

PURPOSE

This study evaluates bone regeneration of critical sized cranial vault defects in New Zealand white rabbits using four commercially available bone substitutes: OsteoSet (calcium sulphate pellets), DynaGraft Putty (demineralized bone matrix delivered in a poloxmer excipient), Norian CRS, and Bone Source (two commercially available calcium phosphate cements).

MATERIALS AND METHODS

Critical sized defects 15 mm in diameter were created bilaterally in the parietal bones of 30 adult male New Zealand White rabbits. They were divided into three groups with ten animals in each. Bone healing was assessed clinically, radiographically, and histomorphometrically. Group 1 had calcium sulfate bioimplant on one side of the calvarium and an unfilled defect on the contralateral side. Group 2 had DBM putty on one side and Poloxamer gel on the contralateral side. Group 3, the Calcium phosphate cements (CPC), had Norian CRS on one side and Bone Source on the contralateral side. Five animals in each group were killed at 6 weeks and 12 weeks post operatively.

RESULTS

All unfilled defects healed with fibrous scar, as did the Plaster of Paris and the poloxamer gel defects. Defects reconstructed with the demineralized bone matrix putty healed with bone throughout the entire defect. This was obvious clinically and radiographically where the defects appeared completely filled with a dense radiopaque tissue. The six-week group displayed new bone formation (87.1%) surrounding the remaining allogeneic particles. Resorption was evidenced by the presence of osteoclastic activity and by the significant decrease in the size of the demineralized bone particles. By 12 weeks, the demineralized bone putty bioimplant was almost completely replaced by new bone (95.5%). Both calcium phosphate cement groups (Norian CRS and Bone Source) had identical patterns of healing. They clinically were visible and firm and uniformly radiopaque with little evidence of new bone formation. Histologically the cement remained unresorbed with little new bone with in the defect at 12 weeks.

CONCLUSIONS

The utilization of a demineralized bone matrix putty appeared to allow for complete closure of critical sized calvarial defects in New Zealand white rabbits with viable new bone at 12 weeks.

Thirty-six month follow-up of 25 patients treated with combination anorganic bovine-derived hydroxyapatite matrix (ABM)/cell-binding peptide (P-15) bone replacement grafts in human infrabony defects. I. Clinical findings

BACKGROUND

Long-term evaluation of periodontal therapy is important for clinical decision making.

METHODS

A synthetic cell-binding peptide (P-15) combined with anorganic bovine-derived hydroxyapatite bone matrix (ABM) was evaluated as a bone replacement graft in human periodontal osseous defects. Following initial preparation and reevaluation, flap surgery was performed. A variety of 1-, 2-, 3-wall bony defects were curetted and root surfaces subjected to mechanical debridement only. The bone defects were grafted with ABM/P-15, and the host flaps replaced or slightly coronally positioned. Weekly, then monthly deplaquing was performed until surgical reentry at 6 to 7 months. Patients were then followed on approximate 3-month recalls for 3 years. Twenty-five of the original 31 patients qualified for long-term evaluation in that their ABM/P-15 treated sites did not receive any additional therapy at the time of reentry.

RESULTS

Significant clinical changes for the overall group of bony defects included improvement in mean clinical attachment level from 5.4 mm at surgery to 4.5 mm at the 6-month reentry to 3.8 mm at 3 years. There was also a decrease in mean probing depth from 5.3 mm at surgery to 3.1 mm at the 6-month reentry to 2.9 mm at 3 years. The mean gingival recession changed from +0.1 mm at surgery to 1.4 mm at the 6-month reentry to 0.9 mm at 3 years. All of these differences were at least P <0.05 from surgery to the 6-month reentry, and surgery to 3 years, but were not significant from reentry to 3 years via repeated measures analysis of variance.

CONCLUSIONS

These favorable 3-year results with ABM/P-15 suggest that it may have a beneficial effect in the long-term clinical management of infrabony defects. Further long-term randomized controlled studies are needed to better assess the role of ABM/P-15 in long-term healing of periodontal osseous defects.

[Experimental study on subcutaneous bone formation by marrow stromal osteoblast-cancellous bone matrix compound artificial bone]

OBJECTIVE

To investigate the feasibility of using marrow stromal osteoblast (MSO) as bone derived cell and using cancellous bone matrix (CBM) as scaffold for bone tissue engineering, the subcutaneous osteogenesis of MSO-CBM compound artificial bone (MCCAB) was observed in the experiment.

METHODS

The marrow stromal cells of adult New Zealand rabbits cultivated and induced in vitro were used to form MCCAB by mixing, seeding and solidifying methods assisted by alginate. The MCCABs were auto-transplanted subcutaneously into the rabbits for 4 to 8 weeks. The alginate-cancellous bone matrix composites or the cancellous bone matrix alone were implanted as control. The effectiveness of bone formation was assessed by means of roentgenography, histology and computerized histomorphometry.

RESULTS

The osteogenesis of MCCABs was better than that of the alginate-cancellous bone matrix composites and of the cancellous bone matrixes. In the MCCABs, both intramembranous and cartilaginous osteogeneses were seen but the former was obvious. In the control, only slight cartilaginous osteogeneses were seen.

CONCLUSIONS

The osteogeneses of the MCCABs constructed by using tissue engineering method were obvious when transplanted subcutaneously. The MSO and CBM can be used as good bone-derived cell and scaffold material respectively for tissue-engineered bone construction.

Sinus floor augmentation at the time of maxillary molar extraction: success and failure rates of 137 implants in function for up to 3 years

BACKGROUND

Implant restoration of the posterior maxilla poses significant challenges to the clinician. In an effort to increase the apical occlusal dimension of available bone for implant placement, a number of sinus augmentation approaches have been suggested. This paper describes a simplified technique for predictable sinus augmentation at the time of maxillary molar extraction.

METHODS

A modified trephine and osteotome technique was utilized to implode the interradicular bone following maxillary molar extraction. Particulate material and a membrane were then placed to maximize regeneration of alveolar bone.

RESULTS

One hundred sixty-seven (167) implants were subsequently placed in regenerated bone following the above technique. One hundred thirty-seven (137) of these implants were restored and in function for up to 3 years at the time of statistical compilation, and 136 of the 137 implants were functioning successfully by the Albrekteson criteria for a cumulative success rate of 97.8%.

CONCLUSIONS

The technique presented for simultaneous sinus augmentation at the time of molar extraction, followed by subsequent implant placement after maturation of regenerating tissues, demonstrates a high success rate for up to 3 years in function. Long-term studies may be useful in evaluating the continual efficacy of such an approach.

Mandibular reconstruction with prefabricated vascularized bone grafts using recombinant human osteogenic protein-1: an experimental study in miniature pigs. Part II: transplantation

Osteogenic Protein-1 (rhOP-1), also called bone morphogenetic protein-7 (BMP-7), is osteoinductive. The aim of this study was to present a new surgical technique: the prefabrication of a vascularized bone graft using rhOP-1 and its microsurgical transplantation. During 6 weeks, osteomuscular grafts were prefabricated in the latissimus dorsi muscle of five adult minipigs. Six hundred micrograms rhOP-1 on a carrier of xenogenic bone mineral in block form were used. The grafts were transplanted into defects of the mandibular angles performing a microsurgical anastomosis and using miniplates for fixation. Identical defects of the contralateral side were treated by direct application of 600 microg rhOP-1 and xenogenic bone mineral. A polychrome sequential labelling was applied. After transplantation the bone stayed viable, demonstrated by continuous apposition of fluorochromes (non-decalcified histologic sections) and bone scintigraphy. The reconstructive result was significantly superior in the prefabrication technique, assessed by histology and computerized tomography (CT). In conclusion, the method has a potential to become a clinical alternative for conventional vascularized bone grafts.

[Preparation of decalcified bone matrix, bone cement and bone morphogenetic protein composite]

OBJECTIVE

To investigate the most excellent composite proportion and the most convenient composite method of decalcified bone matrix (DBM), bone cement (BC) and bovine bone morphogenetic protein (bBMP) composite.

METHODS

The canine DBM and the bBMP were prepared beforehand. First mix the bBMP and DBM together with the proportion of 1:25 with adsorption and directly, then add BC with different weight proportion and finally the complex material was examined by biomechanics, scan electron microscope, determination of bone inductive activity and implanted into the canine femoral defect caused by microwave-induced hyperthermia.

RESULTS

The bBMP had strong bone inductive activity and had no affect for this function when combined with DBM with different method. There were irregular gaps in the composite and most of them with diameter less than 100 microns and the porosity of the composite was less than 20% when the proportion of DBM was 40%. So it was unfavorable for the new bone to form and the new blood vessels to reconstruct. The DBM and BC could not be combined together when the proportion of DBM was 80%. While the biomechanical intensity of the composite decreased and the qualities of the new bone forming and new blood vessels reconstructing improved successively when the proportion of DBM was from 50% to 75%.

CONCLUSION

It is the most convenient that bBMP is combined with DBM directly while its bone inductive activity could not be affected. The composite material not only has high biomechanical intensity, but also is favorable for new bone to form and new blood vessels to reconstruct when the proportion of DBM is 50% and 60%. So it is favorable for bone repair in the places where need to bear a load. However it is also favorable for bone repair in the places where do not need to bear a load when the proportion of DBM is 75%.

Rabbit bone marrow response to bovine osteoinductive proteins and anorganic bovine bone

The effects caused by the implantation of bioabsorbable hydroxyapatite (HA) bound to a pool of bone morphogenetic proteins (BMPs) and other bone noncollagenous hydrophobic proteins mixed with anorganic bovine bone inside rabbit bone marrow were assessed. Within the interior of hollow cylindric titanium prototypes, the following biomaterials were inserted: (1) test group: HA containing a pool of BMPs and noncollagenous hydrophobic proteins mixed with anorganic bovine bone; (2) control group: HA without any protein mixed with anorganic bovine bone; and (3) negative control group: blood clot. The cylinders were placed surgically into the medial portion of the tibiae of 7 rabbits in a manner that allowed the biomaterials to contact just the bone marrow. Morphometric analysis showed that: (1) the biomaterials containing the protein mixture resulted in significantly less new bone than the biomaterials without such a mixture; (2) the group without the protein pool formed larger amounts of bone within the cylinder when compared to the negative control (blood clot only); and (3) the biomaterials containing the protein pool did not show any difference in relation to the negative control. It was concluded that a pool of BMPs and other bone noncollagenous hydrophobic proteins had an inhibitory effect on osteogenesis, and that the biomaterials without a protein pool formed a favorable substrate to bone formation.

The effectiveness of enamel matrix proteins used in combination with bovine porous bone mineral in the treatment of intrabony defects in humans

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of enamel matrix proteins (EMPs) used in combination with bovine porous bone mineral (BPBM), compared to open flap debridement (OFD) in the treatment of intrabony defects in humans.

MATERIAL AND METHODS

Using a split-mouth design, 24 paired intrabony defects were surgically treated and re-entered 6 months later. Experimental sites were treated with EMPs and grafted with BPBM. Control sites were treated with an OFD. The primary outcomes evaluated in the study were changes in pocket depth, clinical attachment level and defect bone fill.

RESULTS

Preoperative pocket depths, attachment levels and intra-operative bone measurements were similar for control and experimental sites. 6-month post surgical measurements revealed a significantly greater reduction in pocket depth (differences of 2.35+/-0.86 mm on buccal and 2.28+/-0.90 mm on lingual measurements) and more gain in clinical attachment (differences of 2.04+/-0.28 mm on buccal and 1.99+/-0.26 mm on lingual measurements) in the experimental sites. Surgical reentry of the defects revealed a significantly greater amount of defect fill in favor of the experimental sites (differences of 2.85+/-0.28 mm on buccal and 2.67+/-0.33 mm on lingual measurements).

CONCLUSIONS

The results of this study suggest that combining EMPs and BPBM as a regenerative technique for intraosseous defects results in statistically and clinically significant more favorable results than OFD. The nature of the attachment between the newly regenerated tissue and the root surfaces needs to be evaluated histologically to confirm the presence of new attachment.

Demineralized bone matrix as an alternative for mastoid obliteration and posterior canal wall reconstruction: results in an animal model

HYPOTHESIS

This study was conducted to evaluate the use of Grafton human demineralized bone matrix as a graft material for mastoid cavity obliteration and canal wall reconstruction in an animal model.

BACKGROUND

Canal wall down procedures in the treatment of cholesteatoma may result in a problematic mastoid cavity. Elimination of the mastoid cavity by obliteration or canal wall reconstruction can prevent or correct this problem. Many techniques and implant materials have been used for this application, yet no single material has proven to be ideal.

METHODS

Athymic rats received tympanic bulla obliteration and lateral bulla wall reconstruction utilizing the Grafton Putty and Flex formulations, respectively. Wound healing was monitored twice a week. Auditory brainstem evoked responses were obtained 8 weeks after implantation. Nine weeks after implantation, the animals were killed, and histologic sections were prepared. A histologic bone formation score (range 0-4) was determined for each implant.

RESULTS

Wound healing occurred without complication. Auditory brainstem response thresholds (average 23.5) fell within the normal range for all ears tested. The average histologic bone formation score for all implants was 3.7. The average scores for obliteration implants and wall reconstruction implants were 3.5 and 3.9, respectively. All wall reconstruction implants underwent partial or total collapse into the bulla.

CONCLUSIONS

The high level of bone formation obtained by the use of Grafton implants in this study makes this material a promising resource for use in mastoid obliteration. The use of the material for canal wall reconstruction will likely require a sturdier preparation to prevent collapse into the mastoid cavity.