Clinical evaluation of bioactive glass in the treatment of periodontal osseous defects in humans

The purpose of this study was to compare the use of bioactive glass to demineralized freeze-dried bone allograft (DFDBA) in the treatment of human periodontal osseous defects. Fifteen systemically healthy patients (6 males and 9 females, aged 30 to 63) with moderate to advanced adult periodontitis were selected for the study. All patients underwent initial therapy, which included scaling and root planing, oral hygiene instruction, and an occlusal adjustment when indicated, followed by re-evaluation 4 to 6 weeks later. Paired osseous defects in each subject were randomly selected to receive grafts of bioactive glass or DFDBA. Both soft and hard tissue measurements were taken the day of surgery (baseline) and at the 6-month re-entry surgery. The clinical examiner was calibrated and blinded to the surgical procedures, while the surgeon was masked to the clinical measurements. Statistical analysis was performed by using the paired Student's t test. The results indicated that probing depths were reduced by 3.07 +/- 0.80 mm with the bioactive glass and 2.60 +/- 1.40 mm with DFDBA. Sites grafted with bioactive glass resulted in 2.27 +/- 0.88 mm attachment level gain, while sites grafted with DFDBA had a 1.93 +/- 1.33 mm gain in attachment. Bioactive glass sites displayed 0.53 +/- 0.64 mm of crestal resorption and 2.73 mm bone fill. DFDBA-grafted sites experienced 0.80 +/- 0.56 mm of crestal resorption and 2.80 mm defect fill. The use of bioactive glass resulted in 61.8% bone fill and 73.33% defect resolution. DFDBA-grafted defects showed similar results, with 62.5% bone fill and 80.87% defect resolution. Both treatments provided soft and hard tissue improvements when compared to baseline (P < or = 0.0001). No statistical difference was found when comparing bioactive glass to DFDBA; however, studies with larger sample sizes may reveal true differences between the materials. This study suggests that bioactive glass is capable of producing results in the short term (6 months) similar to that of DFDBA when used in moderate to deep intrabony periodontal defects.

The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report

Alveolar ridge preservation following tooth extraction is important when implant-supported oral rehabilitation is considered. The ability to maintain the ridge allows implant placement in an ideal position, fulfilling both functional and esthetic demands. A deproteinized bovine bone mineral (DBBM) was used as a socket site filler material to maintain ridge configuration, without applying an occlusive membrane. The material was grafted and packed onto the socket sites immediately after extractions, and subsequently primary soft tissue closure was attempted. The ridge healed for 9 months before the second surgical procedure, in which the implant was placed. New bone formation was observed in all histological specimens. DBBM particles adhered to a highly osteocyte-rich woven and lamellar-type bone. Clinically and histologically, this report demonstrated DBBM particles to be an effective biocompatible filler agent in extraction sockets for ridge preservation prior to titanium fixture implantation. Randomized controlled clinical trials are needed to fully evaluate the usefulness of this material in ridge preservation after tooth extraction.

Effect of a calcium sulfate implant with calcium sulfate barrier on periodontal healing in 3-wall intrabony defects in dogs

This controlled, split-mouth, preclinical study was designed to evaluate outcome following surgical implantation of an allogeneic, freeze-dried demineralized bone matrix-calcium sulfate (DBM+CS) composite with a CS barrier in 3-wall intrabony periodontal defects in 4 dogs. Control conditions included surgical implantation of DBM or CS and gingival flap surgery (GFS) alone. Three-wall intrabony defects (4x4x4 mm) were surgically created at the mesial and distal aspect of the maxillary and mandibular first and third premolars, respectively. Maxillary and mandibular defects each received 1 of the 4 experimental conditions. Experimental conditions were rotated between defect sites in subsequent animals. Block sections of the defects were collected at sacrifice 8 weeks postsurgery and processed for histometric analysis. Histometric defect height (means +/- SD) for the DBM+CS, DBM, CS, and GFS groups amounted to 4.2 +/- 0.5, 4.3 +/- 0.7, 4.0 +/- 0.2, and 4.1 +/- 0.2 mm, respectively. Connective tissue adhesion (connective tissue contact to the root without apparent cementum formation) amounted to 0.4 +/- 0.3, 0.4 +/- 0.3, 0.5 +/- 0.2, and 1.6 +/- 0.5 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Cementum regeneration amounted to 3.0 +/- 0.3, 3.1 +/- 0.4, 2.5 +/- 0.4, and 1.6 +/- 0.3 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being significantly different from the GFS group (P < 0.05). Alveolar bone regeneration amounted to 2.7 +/- 0.4, 2.7 +/- 0.3, 1.8 +/- 0.5, and 0.7 +/- 0.1 mm for the DBM+CS, DBM, CS, and GFS groups, respectively; the DBM+CS, DBM, and CS groups being different from the GFS group (P < 0.05), and the DBM+CS and DBM groups being different from the CS group (P < 0.05). None of the DBM-containing implants provided evidence of bone metabolic activity. In summary, surgical implantation of DBM and CS, alone or in combination, may result in significantly improved regeneration of alveolar bone and cementum in this preclinical model. Observed regeneration is likely unrelated to a biologic activity inherent in DBM. Rather it appears that space-providing properties of the implants supported observed regeneration.

Report of the Sinus Consensus Conference of 1996

Retrospective data from sinus floor augmentation bone grafts were collected from 38 surgeons for 1007 sinus grafts that involved the placement of 2997 implants over a 10-year period, with the majority of the implants followed for 3 years or more postrestoration. There were 229 implant failures reported. Various root-form implants and grafting modalities were used. A consensus conference was organized to evaluate the data and reach a consensus on optimal treatment protocols. The complete database demonstrated a 90.0% success rate for implants placed in sinus grafts with at least 3 years of function. Differences in grafting materials, implant surfaces, and timing protocols were statistically analyzed. However, the database was so multivariate and multifactorial that it was difficult to draw definitive conclusions; these must await controlled prospective studies. The consensus conference therefore developed and voted on multiple consensus statements derived by committee review for bone graft materials, type of implants, timing for implant placement, failure analysis, radiographic analysis, indications/contraindications, prosthetics, and nomenclature. Several consensus statements were obtained, the most significant being that the sinus graft should now be considered a highly predictable and effective therapeutic modality.

Evaluation of a new bioresorbable barrier to facilitate guided bone regeneration around exposed implant threads. An experimental study in the monkey

The aim of this study was to evaluate the effectiveness of a new bioresorbable barrier alone or in combination with BioOss for guided bone regeneration around dental implants with exposed implant threads. Five adult Macaca fascicularis monkeys were used in this investigation. After extraction of all premolars and first molars, two endosteal oral implants were installed in each quadrant and the bony defects were randomly treated with either: 1) placement of the new bioresorbable device alone (group 1); 2) placement of the new bioresorbable barrier in combination with BioOss (group 2); 3) placement of an ePTFE barrier in combination with BioOss (group 3); or (4) control (group 4). After a period of six months the animals were killed and the histological processing was performed. There was a significant difference in the amount of new bone regeneration around the implants between the four groups (i.e. groups 1, 2, 3 and 4) (P=0.0122). There was no difference, however, between group 2 and group 3. It can be concluded that the new bioresorbable barrier in combination with BioOss appears to obtain the same results in this type of bony defects as the grafting material in combination with an ePTFE barrier.

Long-term evaluation of the use of coralline hydroxyapatite in orthognathic surgery

PURPOSE

This prospective study was designed to evaluate the long-term clinical and radiographic results of porous block hydroxyapatite (PBHA) used as a synthetic bone graft in orthognathic surgery and craniofacial augmentation.

PATIENTS AND MATERIALS

A total of 245 consecutive patients were treated initially. Inclusion criteria for this study included a minimum clinical and radiographic follow-up of 5 years. In addition, all patients with known implant failures were included regardless of whether they met the study criteria. There were 111 patients that met the criteria for inclusion in this study. All patients had undergone orthognathic surgery with rigid fixation and had had inlay or onlay PBHA implants placed. Ninety-six percent of the implants were placed through an intraoral approach. Long-term postoperative radiographs were visually compared with immediate postoperative radiographs for implant position, stability, resorption, and other significant radiographic changes. The clinical examination evaluated for signs and symptoms of infection, wound dehiscence, implant exposure, implant displacement, changes in the overlying mucosa, and development of oronasal or oroantral fistulae.

RESULTS

Four hundred seventy-one implants were placed: 403 in the maxilla, 44 in the mandible, and 24 in the periorbital region. There were 289 implants placed in direct communication with the maxillary sinus. The average follow-up time was 7.2 years (range, 5.0 to 10.3 years). Twenty-three implants (4.9%) were removed during the evaluation period. Lateral maxillary wall grafting had 95.7% success, with nine implants being lost in three patients. One chin implant was removed because of dissatisfaction with the aesthetics. Seven (14%) midpalatal implants used for maxillary expansion were lost, primarily because of exposure of the implant to the oral or nasal cavity at the time of surgery. When PBHA was used for alveolar cleft grafting, there was a 100% failure rate.

CONCLUSION

The use of PBHA as a bone graft substitute in orthognathic surgery and for facial augmentation showed a high percentage of success and efficacy. However, adequate soft tissue coverage in the nasal floor and on the palate are paramount for success of midpalatal implants. PBHA should not be used for alveolar cleft grafting. Rigid fixation for inlay implants in the maxilla is important to provide stress shielding of the material and minimize micromovement during the initial healing phase.

The effects of guided bone regeneration and grafting on implants placed into immediate extraction sockets. An experimental study in dogs

Guided bone regeneration (gbr) for the treatment of insufficient bone volume around implants can be performed using membranes with or without grafting materials (i.e., autogenous, allogenous, xenogenous, or alloplastic grafts). A possible way to evaluate the quality of implant osseointegration is the torque necessary to remove implants from their bony housing. The aim of this study was to compare the torques necessary to remove dental implants from implant beds reconstructed with different bone substitutes and GBR or GBR alone in 6 adult mongrel dogs. All mandibular premolars were extracted and 3 extraction sockets on each side were enlarged using a trephine bur. A 13 mm titanium screw-type dental implant (3.75 mm diameter) was placed in each enlarged extraction socket so that only the apical 3 to 4 mm were engaged in bone. The 3 defects were then randomly treated with either 1) canine demineralized freeze-dried bone allograft (DFDBA) plus GBR using an expanded polytetrafluoroethylene membrane (DFDBA+GTAM); 2) bioabsorbable hydroxyapatite and GBR (HA+GTAM); or 3) GBR (GTAM alone). After 6 months, the torque to remove the implants was measured in 4 animals and analyzed using ANOVA. There were no statistically significant differences between the 3 groups (GTAM alone: 46.37+/-16.41 Ncm; HA+GTAM: 46.00+/-16.59 Ncm; DFDBA+ GTAM: 52.15+/-29.24 Ncm). In addition, the influence of early removal of barriers on the torque values was evaluated with the t-test. Comparing exposed versus retained membranes by treatment modality, the only statistically significant difference was found in the DFDBA+GTAM group. When the torque values of all implants with exposed and retrieved membranes were compared to all those with retained membranes a significant difference could be detected. Histologic sections were prepared from the 2 dogs not included in the removal torque testing. In the histometric analysis the GTAM alone group showed a mean mineralized bone-to-implant-contact of 27.1%, the DFDBA+GTAM group of 34.6%, and the HA+GTAM of 39.3%. The mineralized bone-to-implant-contact of the HA+GTAM group was significantly higher than that of the GTAM alone group. In addition, the mineralized bone-to-implant-contact was divided into an apical and coronal part using the apical seventh thread as the dividing landmark. In the apical region, there was no significant difference between the groups regarding mineralized bone-to-implant-contact. In the coronal part the mineralized bone-to-implant-contact of the GTAM alone group was significantly lower compared to the other 2 groups. Within the limits of this investigation, it can be concluded that the type of grafting material will not influence torque removal values, but that early membrane exposure and removal will negatively influence the torque measurements. The combination of GBR with a bone substitute increased the mineralized bone-to-implant contact.

Cranioplasty performed with a new osteoconductive osteoinducing hydroxyapatite-derived material

OBJECT

Cranioplasty is required to protect underlying brain, correct major aesthetic deformities, or both. The ideal material for this purpose is autogenous bone. When this is not available, alloplastic or artificial materials may be used. These materials should be malleable, strong, lightweight, inert, noncarcinogenic, nonferromagnetic, and, if possible, inexpensive. The authors reviewed their surgical experience with a new bone substitute and discuss outcomes in patients in whom it was used.

METHODS

The 11 patients presented in this series had bone defects resulting from bone-involving tumor (eight cases), trauma (two cases), or aesthetic deformity due to repeated craniotomies (one case). The defects were repaired using Osprogel, a bone substitute that consists of calcium hydroxyapatite combined with synthetic, human bone-derived gelatin, glycerol, and water. Osprogel is not only a bioinert material but also an osteoconductive and osteoinducing substrate; when it is placed in contact with healthy cancellous bone, it induces osteogenesis and angiogenesis, thus permitting the regrowth of nearly normal bone. The sheet of Osprogel was modeled onto the cranial defect intraoperatively and was kept in place either by using a titanium micronet secured to surrounding bone with microscrews (first two cases) or by using a single- or double-layer titanium mesh secured with stitches. No complications due to the procedure were observed. The results, evaluated at least 6 months after surgery by using three-dimensional (3-D) reconstructed computerized tomography scans, were excellent in seven patients, good in three, and fair in one. In the patient with a fair result, the repair was unsatisfactory because there was lack of experience in using the material. In part of the area to be repaired, the Osprogel was used as filler; here it was washed out and resorbed. The cases deemed as having a good result had good bone replacement; however, the curvature was faulty.

CONCLUSIONS

In the near future, this technique may be refined to achieve good or excellent results either without the use of supporting material or with the use of individual, computer-designed 3-D prostheses.

Maxillary sinus augmentation in the non-human primate: a comparative radiographic and histologic study between recombinant human osteogenic protein-1 and natural bone mineral

The posterior maxilla has traditionally been one of the most difficult areas to successfully place dental implants due to poor bone quality and close approximation to the maxillary sinus. Sinus augmentation procedures have become a viable means of assuring adequate bone for the placement of dental implants in this area. However, with the techniques currently employed, a considerable variation in the quality of bone attained with the sinus augmentation procedure exists. The purpose of this in vivo study was to evaluate the healing response and bone formation stimulated by 3 doses of recombinant human osteogenic protein-1 (rhOP-1), 0.25, 0.6, and 2.5 mg OP-1 per gram of collagen matrix; natural bone mineral; or collagen matrix alone (control) placed in the maxillary sinus of adult chimpanzees. Results were assessed using clinical, histologic, and radiographic techniques. Radiographic analysis of the computed tomography scans taken at 1 week, and 2.5, 4.5, and 6.5 months revealed a more rapid mineralization with the 2.5 mg OP-1/g collagen matrix and natural bone mineral treatment groups. The incremental bone mineral density (BMD) increase for these 2 treatments from 1 week to 2.5 months was over 2.5 times the increase found with the collagen matrix alone; these 2 treatments also had a higher BMD at the most superior slices evaluated when compared to the other 3 groups. Biopsy specimens were taken at 3.5, 5.5, and 7.5 months and for all 5 treatment groups bone formation was observed at all time points in the majority of the specimens. At 7.5 months the 2.5 and 0.6 mg OP-1/g collagen matrix treatment groups had an increase in the percent bone area when compared to the matrix alone control. In conclusion, these results demonstrate that sinus augmentation with natural bone mineral or 2.5 mg OP-1/g collagen matrix induce comparable radiographic and histologic evidence of bone formation and that both of these treatments performed superior to the control group of collagen matrix alone based upon all methods of evaluation.

Clinical, radiographic, and histologic evaluation of human periodontal defects treated with Bio-Oss and Bio-Gide

This study evaluated the clinical, radiographic, and histologic response to Bio-Oss porous bone mineral when used alone or in combination with Bio-Gide bilayer collagen membrane in human periodontal defects. Four intrabony periodontal defects were treated: two received Bio-Oss alone and two were treated with a combination of Bio-Oss and Bio-Gide. Radiographs, clinical probing depths and attachment levels were obtained preoperatively and 6 to 9 months postoperative, and teeth and surrounding tissues were biopsied. Both treatments significantly improved clinical probing depths and attachment levels, and the radiographic appearance suggested osseous fill. Histologic evaluation revealed that both treatments produced new cementum with inserting collagen fibers and new bone formation on the surface of the graft particles; this regenerative effect was more pronounced using the Bio-Oss/Bio-Gide combination, which resulted in 7 mm of new cementum and periodontal ligament and extensive new bone incorporating the graft. The membrane was intact at 7 months and partially degraded by 9 months after treatment. This human histologic study demonstrates that the porous bone mineral matrix used has the capacity to stimulate substantial new bone and cementum formation and that this capacity is further increased when the graft is used with a slowly resorbing collagen membrane.

[Powdered eggshell in the repair of cystic cavities of the jaw. Preliminary study]

This paper is a clinical report on the use of eggshell as a bone substitute in oral surgery. Five volunteers who presented with a cystic cavity of the jaw with a mean size of 2 x 1 cm, were enrolled in the study. After enucleation of the cyst, the cavity was packed with eggshell powder. The results were assessed by clinical examination and repeated radiological examination at 2, 4, and 6 weeks. Two operative sites were checked at 2 months for histological examination. Clinically, the eggshell implants were very well tolerated. In 3 out of 5 patients, a progressive opacification of the cavities with a centripetal ossification occurred within 6 weeks. In one patient, a generalized resorption was noticed. Histological examination confirmed that eggshell powder was not osteoinductive, but it enhanced the bone regeneration from the margins. In conclusions, eggshell powder is a worth-while bone substitute because it is a safe and easily available material. However, only a modest beneficial effect can be expected on bone regeneration.

Bone replacement grafts. The bone substitutes

Bone substitutes will play a pivotal role in the future of periodontal regeneration. They are synthetically derived or processed from exoskeletons of other species (xenograft) and are an alternative to autogenous or allogeneic bone replacement grafts. Bone substitutes do not provide the cellular elements necessary for osteogenesis, and they cannot be considered osteoinductive, but instead are osteoconductive, providing a scaffold for new bone deposition. Currently, significant decreases in clinical probing depth and attachment levels have been reported with bone substitutes when compared to flap debridement surgery alone for periodontal osseous defects. Reported differences among bone substitutes, autogenous grafts, and allograft materials, occur with respect to histologic outcomes. Overall, probing depth reduction and attachment level gains are similar for all bone replacement grafts.

Effect of calcium sulphate on the healing of periodontal intrabony defects

The purpose of this series of three studies was to evaluate the regenerative potential of calcium sulphate in the treatment of periodontal intrabony defects.

Multi-center clinical evaluation of combination anorganic bovine-derived hydroxyapatite matrix (ABM)/cell binding peptide (P-15) as a bone replacement graft material in human periodontal osseous defects. 6-month results

A synthetic cell-binding peptide (P-15) combined with anorganic bovine-derived hydroxyapatite bone matrix (ABM) was compared to demineralized freeze-dried bone allograft (DFDBA) and open flap debridement (DEBR) in human periodontal osseous defects in a controlled, monitored, multi-center trial. Following appropriate initial preparation procedures, flap surgery with defect and root debridement was performed. Three osseous defects per patient were treated randomly with one of three procedures after surgical preparation. Appropriate periodontal maintenance schedules were followed, and at 6 to 7 months re-entry flap surgery was performed for documentation and finalization of treatment. Analysis of variation (ANOVA) and t test analyses of patient mean values from 31 patients revealed that the combination ABM/P-15 grafts demonstrated significantly better mean defect fill of 2.8 +/- 1.2 mm (72.3%) versus a mean defect fill of 2.0 +/- 1.4 mm (51.4%) for defects treated with DFDBA (P <0.05) and a mean defect fill of 1.5 +/- 1.3 mm (40.3%) (P <0.05) for defects treated with DEBR. Other hard tissue findings showed similar clinically superior results with the use of ABM/P-15. Relative defect fill results showed 87% positive (50% to 100% defect fill) responses with ABM/P-15, 58% positive responses with DFDBA, and 41% positive responses with DEBR. There were 8 to 9 times more failures (minimal response) with DFDBA and DEBR (26% to 29% frequency) than with ABM/P-15. Soft tissue findings showed no significant differences among treatments except for greater clinical attachment level gain with ABM/P-15 compared to DEBR. These results suggest that the use of the P-15 synthetic cell-binding peptide combined with ABM yields better clinical results than either DFDBA or DEBR. Further studies are needed to determine the relative roles of the ABM and/or the P-15 in these improved results.

Comparison of bioactive glass synthetic bone graft particles and open debridement in the treatment of human periodontal defects. A clinical study

The purpose of this study was to compare the repair response of bioactive glass synthetic bone graft particles and open debridement in the treatment of human periodontal osseous defects. Fifty-nine defects in 16 healthy adults were selected. Each patient had at least 2 sites with attachment loss of at least 6 mm with clinical and radiographic evidence of intrabony or furcation defects. One to 3 months after cause-related therapy (oral hygiene instructions, scaling and root planing), the following measurements were recorded prior to surgery: probing depths, clinical attachment level, and gingival recession. Each defect was surgically exposed and measurements made of the alveolar crest height and base of osseous defect. The test defects were implanted with bioactive glass. The other sites served as unimplanted controls. Flaps were sutured at or close to the presurgical level. Radiographs and soft tissue presurgical measurements were repeated at 6, 9, and 12 months. At 12 months all sites were surgically re-entered to record osseous measurements. At the 12-month evaluation, significantly greater mean probing depth reduction was noted in the bioactive glass group compared to the controls (4.26 mm versus 3.44 mm; P = 0.028). Clinical attachment level gain was significantly improved (P = 0.0004) in the bioactive glass sites (2.96 mm) compared to the control sites (1.54 mm). There was significantly less gingival recession in the bioactive glass sites (1.29 mm) compared to the control sites (1.87 mm). Defect fill was significantly greater in the bioactive glass sites (3.28 mm) compared to the control sites (1.45 mm). Defect depth reduction was significantly greater in the bioactive glass sites (4.36 mm) compared to the control sites (3.15 mm). In conclusion, bioactive glass showed significant improvement in clinical parameters compared to open flap debridement.

Surgical technique of onlay bone grafting

Different forms of bone grafting materials are alluded to in this paper. Autogenous graft is superior to other bone grafting materials but is many times not available or the patient is not willing to utilize cranial or iliac crest bone. Allografts, Xenografts and bone substitute materials are the most widely used today in dentistry and especially those patients wishing to use dental implants as abutment support. The technique discussed utilizing surgical tissue design, tissue closure over the graft material and the tissue barrier can be used to produce a successful final result using a graft material of choice. It is quite certain that in the near future, the use of bone graft enhancement materials (bone morphogenic protein-like substances) will be used to enhance a quicker result. It is anticipated that growth factors, stimulating factors, bone morphogenetic proteins, and osteogenetic proteins will cause a bone graft to vascularize, solidify, incorporate, and function optimally in a shorter period of time. These materials will reduce the disability time and enhance the outcome of bone grafting in the dental profession. It is also anticipated that advanced tissue surgical techniques will give better vascularization to the new graft. The described technique is predictable and should give the operator the desired result.

Ridge preservation: the new buzzword in dentistry

The viability of Ridge Preservation as achieved by practicing Advanced Extraction Therapy (AET) and Replacement Therapy (R.T.), will impact the future practice of Dentistry. With the availability of clinically proven materials such as implants (titanium) and synthetic bone substitutes (Bioplant HTR), a practical solution exists to solve a very old clinical problem. Treatment modalities are available today making the atrophic jaw-bone a malady of the past. Imagine no more "dental cripples," and no more inadequate bone situations for implant placements. Ridge Preservation and Replacement Therapy should be practiced regularly: "when we take something out, we should put something back." Our practices will grow. Our patients will thank us.

Augmentation genioplasty with hard tissue replacement implants

PURPOSE

This study assessed the soft tissue changes produced by the placement of hard tissue replacement (HTR) polymer chin implants for augmentation genioplasty and evaluated the dimensional stability as well as any bony changes associated with the implants.

PATIENTS AND METHODS

The study group consisted of 18 patients (3 males, 15 females) with an average follow-up of 21.5 months (range, 12 to 44 months). All implants were placed through an intraoral incision and stabilized to the symphysis with a single 2.0-mm diameter titanium screw. Preoperative, postoperative, and long-term cephalometric radiographs were analyzed for changes in soft tissue thickness in the chin region, implant stability, and the presence of bone resorption.

RESULTS

The net hard tissue chin augmentation achieved averaged 6.0 mm (range, 4.5 to 9 mm). Average preoperative soft tissue thickness was 12.1 mm (range, 11 to 14.5 mm) and postoperatively it was 10.6 mm (range, 10 to 13.5 mm). The average increase in soft tissue projection was 77.6% (range, 71.4% to 83.3%) of the implant thickness. There was no radiographic evidence of implant migration or bony resorption beneath the implant.

CONCLUSIONS

HTR implants appear to be a predictable means of augmenting the chin, providing the desired aesthetic change, without causing resorption of underlying bone.

Symptomatic monostotic fibrous dysplasia of the thoracic spine

STUDY DESIGN

A case report of monostotic fibrous dysplasia of the thoracic spine with symptoms of chest and back pain.

OBJECTIVE

To treat this lesion with surgery.

SUMMARY OF BACKGROUND DATA

Monostotic fibrous dysplasia of the thoracic spine is rarely seen. Few reports of this disorder appear in the literature. This is the fifth case of monostotic fibrous dysplasia of the thoracic spine presented to date.

METHODS

The patient was a 48-year-old woman with monostotic fibrous dysplasia involving the thoracic spine of the 10th vertebral body and the 10th left rib. Surgical removal of the tumor was carried out. The defect was packed with hydroxyapatite graft material. Arthrodesis or internal fixation was not made.

RESULTS

The diagnosis of fibrous dysplasia was made histologically. No obvious recurrence of the lesion has been seen for 3 years.

CONCLUSION

Surgical removal of the tumor and transplantation of hydroxyapatite was effective treatment for the reported patient.

Reversing the inhibitory effect of nicotine on spinal fusion using an osteoinductive protein extract

STUDY DESIGN

The effect on spinal fusion of an osteoinductive bone protein extract in the presence of a known inhibitor of spinal fusion (systemic nicotine) was studied prospectively in an animal model of posterolateral lumbar fusion.

OBJECTIVES

To evaluate the ability of a bovine-derived osteoinductive bone protein extract to overcome the inhibitory effect of nicotine in a rabbit spine fusion model.

SUMMARY OF BACKGROUND DATA

Multiple studies have demonstrated the ability of a variety of osteoinductive growth factors to serve as a bone graft substitute for lumbar spinal fusion under "normal" healing conditions.

METHODS

Forty-eight adult female New Zealand white rabbits underwent spine arthrodesis at L5-L6 while receiving systemic nicotine through a subcutaneous miniosmotic pump. Arthrodesis was performed using one of the following three graft materials: 1) autogenous iliac crest, 2) osteoinductive bone protein delivered in an allogeneic demineralized bone matrix/ collagen carrier, or 3) osteoinductive bone protein delivered with autogenous iliac crest. Fusions were assessed by blinded manual palpation, radiography, and biomechanical testing.

RESULTS

Of the 44 rabbits manually tested by blinded observers, all 14 in the osteoinductive bone protein plus autogenous iliac crest bone group had solid fusions (14 of 14), whereas the fusion rate was less in the osteoinductive bone protein plus demineralized bone matrix group (nine of 14, 64%; P = 0.02), and there were no fusions in the autogenous iliac crest only group (0 of 16, 0%; P = 0.000001). The use of osteoinductive bone protein with autogenous bone produced stronger and stiffer fusions compared with those using autogenous bone alone or osteoinductive bone protein with allograft bone.

CONCLUSIONS

Cigarette smoking and nicotine are inhibitory factors in the healing of fractures and spine fusions. This study shows that the inhibitory effect of nicotine can be overcome with an osteoinductive bone growth factor in an animal model.

[Bone substitute with growth factor. Preliminary clinical cases for cranio- and maxillo-facial indications]

Several biological materials have been analyzed in combination with osteo-inductive growths factors to determine whether such a system can replace bone grafting in surgical practice. Efforts have been aimed at the discovery of the best carriers and delivery systems. We present the results of the surgical treatment of 11 cranio-maxillo-facial defects in 9 patients using a combination of natural coral skeleton (NCS in blocks or granules), human fibrin glue and transforming growth factor beta-1 (TGF-beta 1) as a composite bone substitute. Three patients were initially excluded because of early extrusion of the materials due to a technical error. Clinical and radiological evaluation was performed in all cases, with the patient acting as his own control. Clinical firmness and radiological mineralization occurred in three quarters of cases. New bone formation was confirmed histologically in two of these patients. Clinically the initial results remained stable over a three years follow-up with staged surgical procedures performed on a number of patients. None of the patients suffered any detrimental effect from implantation of the bone substitute. Although the numbers in these series are limited, the association of TGF-beta 1, human fibrin glue and NCS represented an interesting step, although the clinical results could be improved. Important factors in the success of this technique appeared to be stabilisation of the biological materials, quality and asepsis of the surrounding tissue and the dose of growth factor.

Histological evaluation of Bio-Oss in a 2-stage sinus floor elevation and implantation procedure. A human case report

Deproteinized cancellous bovine bone (Bio-Oss) was placed as a grafting material for sinus floor elevation in the right posterior maxilla. After 6 months of healing, 3 cylindrical titanium-plasma coated implants were inserted. Six months later at the abutment connection, it was realized that 1 of the implants could not be reconstructed due to unfavorable positioning. This implant was removed along with a small portion of the surrounding peri-implant tissues. The specimen was processed according to standard techniques for hard tissue histology. In both the grafted area and the previously existing area of the sinus floor the bone was primarily of lamellar structure. Intimate contact between newly formed bone and the particles of the graft was present. No overt signs of resorption of the graft particles were visible. Histomorphometric analysis revealed 63% of implant-bone contact in the zone of pre-existing bone, and 73% in the grafted zone. The area density of bone amounted to 27% in the non-grafted as compared to 28% in the grafted area. In conclusion, this case report documented that deproteinized bovine bone, when used as a grafting material for augmentation of the sinus floor, may lead to proper osseointegration of a dental implant.

Synthetic porous ceramic compared with autograft in scoliosis surgery. A prospective, randomized study of 341 patients

We have evaluated the use of a synthetic porous ceramic (Triosite) as a substitute for bone graft in posterior spinal fusion for idiopathic scoliosis. In a prospective, randomised study 341 patients at five hospitals in the UK and France were randomly allocated either to autograft from the iliac crest or rib segments (171) or to receive Triosite blocks (170). All patients were assessed after operation and at 3, 6, 12 and 18 months. The two groups were similar with regard to all demographic and baseline variables, but the 184 treated in France (54%) had Cotrel-Dubouset instrumentation and the 157 treated in the UK usually had Harrington-Luque implants. In the Triosite group the average Cobb angle of the upper curve was 56 degrees, corrected to 24 degrees (57%). At 18 months, the average was 26 degrees (3% loss). In the autograft group the average preoperative upper curve of 53 degrees was corrected to 21 degrees (60%). At 18 months the mean curve was 25 degrees (8% loss). Pain levels after operation were similar in the two groups, being mild in most cases. In the Triosite group only three patients had problems of wound healing, but in the autograft group, 14 patients had delayed healing, infection or haematoma in the spinal wound. In addition, 15 autograft patients had pain at the donor site at three months. Seven had infections, two had haematoma and four had delayed healing. The haematological and serum biochemistry results showed no abnormal trends and no significant differences between the groups. There were no adverse events related to the graft material and no evidence of allergenicity. Our results suggest that Triosite synthetic porous ceramic is a safe and effective substitute for autograft in these patients. Histological findings on biopsy indicate that Triosite provides a favourable scaffolding for the formation of new bone and is gradually incorporated into the fusion mass.

Future directions. Augmentation of osteoporotic vertebral bodies

Because current medical and surgical treatments of vertebral body fractures are less than adequate, there is a need for interventions that decrease the likelihood of occurrence of these fractures and improve the treatment options once they have occurred. One such broad category of intervention involves the fortification or augmentation of the vertebral bodies. In addition to prophylactically stabilizing osteoporotic vertebral bodies at risk for fracture, augmentation of vertebral bodies that have already fractured may prove to be useful by reducing pain, improving function, and preventing further collapse and deformity. Vertebral body augmentation can also be used as an adjunct to fixation of internal hardware--for example, pedicle screws-in osteoporotic spines. A number of products are now available or are in clinical trials. The most promising products are injectable materials-polymethylmethacrylate or mineral bone cement. The early clinical results using polymethylmethacrylate in percutaneous vertebroplasty for fractured vertebral bodies and the results in vitro using an injectable mineral cement for vertebral body fortification are encouraging. Although the principle of vertebral body augmentation remains encouraging, data to support the widespread use of these techniques remain sparse, and the indications for their use should be more clearly defined.

BIO-OSS--a resorbable bone substitute?

BIO-OSS is an allergen-free bone substitute material of bovine origin, used to fill bone defects or to reconstruct ridge configurations. Seventy one patients (39 female, 32 male) received 126 BIO-OSS implantations. Some health parameters or habits were documented to eliminate possible risk factors of influence. The diameter of jaw defects filled with BIO-OSS was measured. There was a significant influence of the defect size on the healing result. In X-ray controls, BIO-OSS served to identify the surrounding native bone. The density of the BIO-OSS areas was higher than in control sites. These radiological results were supported by bone biopsies. Histologically, the permanency of the BIO-OSS was still recognizable after 6 years and longer. The ingrowth of newly formed bone in the BIO-OSS scaffold explained the increased density of the implanted regions. There were no clinical signs of BIO-OSS resorption. Therefore, we can assume that form corrections achieved by BIO-OSS insertions will last.

Repair of craniofacial defects with hydroxyapatite cement

PURPOSE

The objective of this study was to evaluate the course of healing of craniofacial bone defects when filled with hydroxyapatite cement and to determine whether adding various percentages by weight of demineralized bone powder to the cement will result in enhanced bone formation.

MATERIALS AND METHODS

The model for the study was the canine calvarium. The implants were placed into cranial defects and harvested at 3 or 6 months for qualitative evaluation by light microscopy, microradiography, and quantitative histomorphometry.

RESULTS

The implantation of hydroxyapatite cement resulted in characteristic replacement of the material with new bone ingrowth. The addition of demineralized bone powder to the hydroxyapatite cement appeared to improve the handling characteristics of the cement; however, improvement in the replacement of the material by bone was not observed. The implantation of only allogeneic demineralized bone showed limited new bone formation within the defect site.

CONCLUSIONS

Hydroxyapatite cement formed an effective osseoconductive scaffold for bone replacement. The addition of demineralized bone powder to the cement to serve as a carrier of osseoinductive factors did not result in additional bone being formed.

Evaluation of Bioglass/PerioGlas (Consil) synthetic bone graft particulate in the dog and cat

This paper describes the use of Bioglass synthetic bone graft particulate (PerioGlas/Consil) in the treatment of osseous periodontal defects, and in post-extraction sites to maintain the vertical height and width of the alveolar ridge. The material is easy to use, inhibits epithelial down-growth, and acts as a mechanical hemostatic agent. Radiographic follow up in 36 dogs and 5 cats demonstrated significant bone fill. In the osseous periodontal defect treatment group, clinical probing depths decreased significantly, and there was an apparent gain in attachment level.

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part I. Evaluation of anorganic bovine-derived bone matrix

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.

Sinus augmentation for dental implants: the use of autogenous bone

Autogenous bone has been the material of choice at our institution since 1983. The criteria for a successful graft in the sinus have been fulfilled based on functional stability in patients followed-up over 10 years in selected cases. Of 173 implants placed into autogenous bone grafted sinuses, 20 have been lost in four patients. Long-term follow-up is recommended for all graft materials used to support posterior maxillary restorations.

Comparison of porous bone mineral and biologically active glass in critical-sized defects

Several materials have been proposed as therapies to augment alveolar bone and to promote periodontal regeneration. However, there are an insufficient number of studies that effectively evaluated these therapies. Consequently, the purpose of this study was to compare bone regeneration promoted by porous bone mineral and biologically active glass. Unilateral critical-sized defects (CSDs) were prepared in the radii of 24 rabbits, divided evenly between 2 time periods (4 and 8 weeks) and between 2 treatment groups (porous bone mineral and biologically active glass). Evaluations consisted of clinical examinations, standardized radiography at baseline and every 2 weeks thereafter, as well as histology and histomorphometry. Data were analyzed by an unpaired Student t-test with significance established at P < or = 0.05. We determined that CSDs treated with porous bone mineral were significantly more radiopaque than biologically active glass-treated sites at both 4 and 8 weeks. Moreover, the amount of new bone was significantly greater at both 4 and 8 weeks in the porous bone mineral groups than in the biologically active glass groups. We concluded that in the rabbit radius CSD wound model, porous bone mineral appears to be more effective than biologically active glass in regenerating bone.

Resorbable versus nonresorbable membranes in combination with Bio-Oss for guided bone regeneration

The purpose of this clinical investigation was to compare the new resorbable collagen membrane, Bio-Gide, to the conventional expanded polytetrafluoroethylene material (Gore-Tex) for guided bone regeneration in situations involving exposed implant surfaces. Over a 2-year period, 25 split-mouth patients were treated randomly: one defect site was treated with Bio-Gide and the other defect site with Gore-Tex; all 84 defects were filled with Bio-Oss and covered with the respective membrane. The defect types, their dimensions, and their morphology were measured in detail initially and at re-entry to allow for calculation of the exposed implant surface. Changes in defect surface for both types of membranes were statistically significant (P < .0001); however, no statistical significance (P > .94) could be detected between the two membranes. The mean average percentage of bone fill was 92% for Bio-Gide and 78% for Gore-Tex sites. In the latter group, 44% wound dehiscences and/or premature membrane removal occurred. The resorbable membrane, Bio-Gide, in combination with a bone graft, can be a useful alternative to the well-established expanded polytetrafluoroethylene membranes.

Simultaneous hard and soft tissue augmentation for implant-supported single-tooth restorations

The replication of nature in the rehabilitation of a single missing anterior tooth is primarily a surgical challenge, as hard and soft tissue deficiencies compromise the achievement of functional and aesthetic implant-supported restorations. Bone defects can be treated using guided bone regeneration (GBR), with or without bone graft materials. The successful application of the GBR technique has been documented in several experimental and clinical studies; the primary challenge associated with single tooth replacement is the creation of an adequate soft tissue recipient site. However, the increased morbidity and prolonged healing period involved in performing hard and soft tissue grafting procedures in two consecutive appointments do not achieve patient expectations. The learning objective of this article is to master a single-tooth replacement technique that allows surgical treatment of bony and soft tissue deficiencies in a single procedure, during either an immediate or delayed implant placement.

Sinus augmentation for dental implants: the use of alloplastic materials

The ability to augment the sinus floor has dramatically expanded the scope of implant dentistry. Clinical and scientific studies abound as to the efficacy of this procedure. The debate still ensues as to the best material to use for this augmentation, with autogenous bone, freeze-dried bone, xenografts, and alloplasts all being advocated. This article will substantiate through scientific and clinical studies, how the use of allplastic materials in sinus augmentation techniques can greatly reduce the morbidity and the expense of the procedure while predictably producing bone that has been shown to support dental implants in function for extended periods of time.

Effect(s) of the demineralization process on the osteoinductivity of demineralized bone matrix

The relationships between residual calcium levels and particle size of ground demineralized bone matrix and its osteoinductive potential were investigated using in vitro and in vivo assays. The effects of variable residual calcium levels, variable particle sizes, and donor age and gender were studied using a tissue culture-based bioassay (in vitro) as well as an athymic mouse (in vivo) bioassay. The osteoinductive potential of the bone-derived biomaterial was assessed by measuring the degree of new bone formation (change in percent calcium content after 4 weeks of implantation) in the in vivo assay and levels of alkaline phosphatase activity associated with cultures of human periosteal cells (HPO cells) in the in vitro assay, respectively. Slightly demineralized bone matrix and overly demineralized bone matrix possessed a degree of osteoinductive potential whereas bone demineralized to levels of approximately 2% residual calcium provided for maximum osteoinductive potential in both assay systems. The osteoinductive potential of ground demineralized bone varied relative to the particle size such that DBM particles ranging from 500 to 710 microns provided for the highest level of calcium deposition (increase of 8.1 weight percent calcium) after 4 weeks of implantation in muscle pouches of an athymic mouse, whereas explanted particles less than 250 microns showed the lowest level of calcium deposition (increase of only 2.8 weight percent calcium). In the donor age and gender study, DBM from different donors were divided into 5 age groups for both female and male donor derived bone: less than 20, 21 to 30, 31 to 40, 41 to 50, and 51 to 60 year old age groups. This study indicated that DBM from female donors in the 31 to 40 years old age group and male donors in the 41 to 50 year age group possess the highest osteoinductive potential, whereas DBM derived from donor bone from both female and male donors in the 51 to 60 year age group presented the lowest osteoinductive potential. DBM derived from male and female donors did not in general show significant differences in osteoinductive potential.

A quantitative assessment of osteoinductivity of human demineralized bone matrix

Demineralized bone matrix (DBM) is widely used in the repair of pathologies associated with skeletal defects and periodontal diseases. The present study was directed at establishing in vivo and in vitro models for a quantitative assessment of the osteoinductivity of DBM before clinical use. Athymic mice were used in an in vivo assay to overcome the species limitations (for human DBM) found in xenogeneic animal models. Calcium contents of explants, as an indicator of new bone formation, were assayed and expressed as a change in the weight percent calcium in the explant as compared to the weight percent of calcium in the implanted material. A total of 82 mice (2 implants per mouse) were used in this study. Significant amounts of new bone were induced in this animal model in response to implantation of DBM. Muscular implantation was found to be more osteoinductive (increases of 10.0 +/- 0.4 calcium weight percent of explant) than subcutaneous implantation (increases of 1.62 +/- 0.27 calcium weight percent of explant) and new bone formation in muscular implantation sites of athymic mice mimics endochondral bone formation. Between weeks 1 to 4, the weight of explanted materials did not significantly differ from the weight of the implanted material; however, by week 5 the explant weight began to increase. Calcium deposition over the 5 weeks of implantation increased in a nearly linear fashion. Consequently week 4 was chosen as the optimum time for explantation in the in vivo assay in that sufficient calcium levels had been achieved without a significant increase in explant dry weight. Aliquots of 10, 20, 30, and 40 mg per implantation site were used in dose response studies in the in vivo bioassay. Dose response curves with DBM exhibited maximal activity at the 20 mg DBM implant dose in the in vivo bioassay. An in vitro bioassay was also developed where human periosteal (HPO) cells were chosen because osteoprogenitor cells found in bone repair typically come from periosteal tissue. Alkaline phosphatase (ALP) activity in confluent cell cultures of HPO cells exposed to DBM, as an indicator of osteoblast induction, reached its highest level on day 5 of DBM treatment. Aliquots of 2, 5, 10, 20, 30, and 40 mg DBM per flask were chosen in dose response studies using the in vitro bioassay. These dose response studies with DBM revealed that quantities approximating 5 to 10 mg DBM in the in vitro model provided for maximal levels of ALP in cell extracts. A linear correlation (R2 = 0.7397) was demonstrated between the in vivo calcium remineralization assay and the in vitro ALP assay of osteoinductivity of DBM, suggesting that the in vitro assay can be used to quantitatively assess the osteoinductive potential of DBM where production and distribution of clinically usable DBM dictates rapid analysis.

Six-year clinical evaluation of HTR synthetic bone grafts in human grade II molar furcations

A biocompatible microporous composite of PMMA (poly-methyl-methacrylate), PHEMA (poly-hydroxy-ethyl-methacrylate) and calcium hydroxide bone replacement graft material (Bioplant HTR Synthetic Bone) was evaluated in 16 maxillary molar and 10 mandibular molar Grade II furcations in 13 patients. Following initial preparation, full thickness flaps were raised to gain access to the furcations; mechanical hand and ultrasonic root and defect debridement and chemical tetracycline root preparation were performed; furcation and adjacent osseous defects in each patient were grafted with HTR Synthetic Bone; and the host flaps replaced or slightly coronally positioned. Weekly, then monthly deplaquing was performed until surgical re-entry at 6-12 months. Patients were then followed on approximate 3-month recalls for > or = 6 yr. Evaluation of the primary clinical outcome of furcation grade change showed that in the maxilla 5/16 furcations were clinically closed, 9/16 were Grade I, and 2/16 remained Grade II; while in the mandible 3/10 were clinically closed, 5/10 were Grade I, and 2/10 remained Grade II. Other significant clinical changes included decrease in mean horizontal furcation probing attachment level from 4.4 mm at surgery to 2.2 mm at re-entry to 2.0 mm at 6 yr, decrease in probing pocket depth from 5.4 mm at surgery to 3.0 mm at re-entry to 3.2 mm at 6 yr, and improvement in vertical clinical probing attachment level from 5.4 mm at surgery to 4.2 mm at re-entry to 4.1 mm at 6 yr (all p < 0.05 from surgery to re-entry and surgery to 6 yr, n.s. from re-entry to 6 yr via ANOVA). These favorable results with HTR polymer are similar to several reports with other graft materials and with GTR barriers, and suggest that HTR polymer may have a beneficial effect in the clinical management of Grade II molar furcations.

Hydroxyapatite paste (BoneSource) used as an onlay implant for supraorbital and malar augmentation

This study was designed to evaluate hydroxyapatite paste (BoneSource; Leibinger Corp., Dallas, TX) as an alloplastic implant for supraorbital and malar augmentation. Ten male Sprague-Dawley rats had cylindrical onlay implants made of the hydroxyapatite cement placed above their left orbits on the supraorbital rim. Size-matched Medpor implants were placed similarly on the right side. To test the utility of this new material in the midface, hydroxyapatite paste and Medpor implants were also placed in the right malar regions of a different set of rats. The implants were left in situ for 6 months and examined for evidence of bone ingrowth, infection, migration, resorption, and detrimental effects on the surrounding tissue. All hydroxyapatite cement implants provided excellent soft tissue projection and demonstrated steadfast adherence to the adjacent bone. The surface of the hydroxyapatite implant in contact with the native bone demonstrated evidence of native bony ingrowth into approximately 12% of the implant. There was no evidence of implant migration or gross infection. There was no bony resorption below the hydroxyapatite paste, but four of the Medpor implants showed evidence of this in the underlying bone. Only one negative aspect to the use of hydroxyapatite cement paste as an onlay implant was identified. Two of the supraorbital and one of the malar hydroxyapatite implants had approximately 20 to 25% volume loss during the experimental period (P = 0.05). Overall, the vast majority of the implants retained their original form. We concluded that hydroxyapatite paste may possibly be used to effectively augment bone in the supraorbital and malar regions. Its biocompatibility, excellent bony adherence, and tendency to be replaced by natural bone may make it suitable for the aesthetic patient. The possible resorptive aspects of the material need to be evaluated further.

Repair of bone defect in primate mandible using a bone morphogenetic protein (BMP)-hydroxyapatite-collagen composite

The purpose of this study was to evaluate a hydroxyapatite (HA)-collagen (Col)-bone morphogenetic protein (BMP) composite as an osteoinductive bone substitute. Partially-purified BMP from bovine bone was mechanically mixed with highly purified type I collagen from calf dermis and then subsequently mixed with pure synthetic hydroxyapatite granules or block. The HA-Col-BMP composite, or the HA-Col composite as a control, was implanted in a surgically-induced mandible bone defect (6 x 7 x 10 mm) in an adult Japanese monkey. The mandible was excised three months after implantation and studied histologically. The BMP-containing implant induced much more new bone than the control implant in all experimental animals of each group, with either HA granules or HA block. Newly formed bone was attached tightly to HA and infiltrated deeply into the pores of the HA of the BMP-containing implant, while fibrous tissue existed between the host bone and HA in the control implant. Thus, we conclude that an HA-Col-BMP composite could be a superior biomaterial for a bone substitute.

Mandibular fracture after endosseous implant placement in conjunction with inferior alveolar nerve transposition: a patient treatment report

A patient with a severely atrophic right posterior mandible had three endosseous implants placed in conjunction with transposition of the inferior alveolar nerve. Three weeks following implant placement surgery, the patient experienced a spontaneous fracture of the mandible involving the two anterior implants. The two implants were removed, and the fracture was treated with open reduction and fixation with titanium mesh. The fracture healed, and the posterior implant integrated. This report suggests that the buccolingual and superior-inferior position of the mandibular canal can increase the possibility of mandibular fracture by increasing the size of the buccal cortical plate that is removed to expose the nerve during surgery.

Tri-calcium phosphate ceramics and allografts as bone substitutes for spinal fusion in idiopathic scoliosis as bone substitutes for spinal fusion in idiopathic scoliosis: comparative clinical results at four years

The authors present the results of a comparative study of two series of posterolateral arthrodeses for scoliosis performed using COTREL DUBOUSSET instrumentation. Fifty-four consecutive patients underwent surgery for idiopathic scoliosis using the same technique. Thirty received a graft consisting of a mixture of corticocancellous autologous and allogenic bone frozen at -80 degrees, and 24 patients were grafted with a mixture of cortico-cancellous autologous bone and sticks of tricalcium phosphate (TCP, Biosorb, SBM, Lourdes, France). All patients were seen at three, six and twelve months, then once a year for at least four years with clinical and radiological evaluation at each visit. At the final follow up visit, no radiologic signs of pseudoarthrosis were found in either group with a minimum follow-up of 4 years. The appearance of bone callus was considered satisfactory at 6 months in all cases; moreover callus seemed to be more important in the TCP series, although this assessment was subjective. TCP resorption was total after 2 years, while allograft fragments were visible on x-rays after 2 years. Minor mechanical complications occurred but did not influence the results. Loss of correction was 8% of that initially obtained in the allograft group and 2% in the TCP group. Loss of correction did not progress after 6 months in the TCP group and after 2 years in the allograft group. Based upon this experience, the use of synthetic bone substitutes such as TCP would appear to be a valuable alternative to allografts in posterolateral spinal arthrodesis for idiopathic scoliosis, and it would eliminate the risk of viral contamination inherent to allograft implantation. To our knowledge, there have been no previous comparative studies concerning the use of tricalcium phosphate versus allograft in the literature.

Tooth eruption through autogenous and xenogenous bone transplants: a histological and radiographic evaluation in beagle dogs

The effect of implanting autogenous and xenogenous (Bio-Oss) bone transplants into metabolically active sites within beagle dog mandibles during permanent premolar tooth eruption was examined. Ten 14-week-old beagles were used. Before commencing the radiographic experiments, metal bone markers were placed in the caudal margin of the mandible at the age of 10 weeks. The deciduous first and third molar teeth were extracted and their sockets over the permanent second and fourth premolars were implanted with autogenous particulate enchondral iliac crest bone, autogenous particulate membraneous mandibular body bone, xenogenous bovine anorganic bone mineral spongiosa granules (1-2mm3) (Bio-Oss, Geistlich Pharma, Switzerland) of left empty. The third premolar served as control site. Standardized oblique lateral radiographs were taken once a week. A number of coordinates of defined points and structures were determined by means of a coordinate digitizing system. Animals were killed 4, 10 and 16 weeks after bone transplantation for histological examination of the transplantation sites. All premolars showed no delay in eruption or disruption of crown and root development. On histology, the Bio-Oss particles were not resorbed or integrated in the alveolar bone but were pushed forward into the gingiva. We have demonstrated that there is on difference in the eruption curve of the permanent premolars in the four groups (ANOVA P > 0.5) and that bone transplantation has no inhibitory effect on eruption (ANOVA P > 0.3) and crown development of the underlying permanent premolar but that Bio-Oss does not have the same resorbable or integrating capability as autogenous bone grafts.

[A biomechanical study on the bone repairing ability of recombinant human bone morphogenetic protein-2-coral composited artificial bone]

To improve bone repairing ability of coral, recombinant human bone morphogenetic protein-2 (rhBMP-2)-coral composited artificial bone was obtained by combining coral with rhBMP-2 in this experiment. The composite was implanted into rabbit calvarial critical-size defects and coral alone was implanted as control. The bone repairing ability was assessed by radiography, histology and biomechanics. The results showed that implants were absorbed gradually after they was implanted into the defects. In the meantime, the new bone was formed and the mechanical strength was reinforced uninterruptedly in bone defect regions. At 12 weeks, the implants were replaced completely by bone, and the mechanical strength was entirely restored. These suggest that the composite possess a superior bone repairing ability and may be one of the most perfect bone graft substitutes currently available.

[Early observation of healing of rabbit mandibular defects with porous blocks consisting of polylactic acid and recombinant human bone morphogenetic protein-2]

The effects of bone morphogenetic protein (BMP) which can induce bone formation have been surely proved, Porous polylactic-acid blocks were prepared by a freeze-drying method. During preparation of the blocks, recombinant human bone morphogenetic protein-2(rhBMP-2) was mixed with the polylactic-acid(4 mg per block). PLA-rhBMP-2 was implanted in the mandibular defects of rabbit and retrieved after 2 or 4 weeks. The results showed that: with the PLA-rhBMP-2 blocks, new bone formation was observed in 2 weeks after implantation, and plain PLA blocks produced a little of new bone formation in the edges of defect even in 4 weeks after implantation. Calcium content of the retrieved PLA-rhBMP-2 block was statistically higher than that of plain PLA blocks. These results suggest that PLA may be effective delivery system for BMP and the PLA/rhBMP-2 block may potentially have usefulness as a bone graft substitute.

Barrier membrane techniques in endodontic microsurgery

The ultimate goal in endodontic microsurgery is the predictable regeneration of periapical tissues. One of the main concerns in treating an endodontically treated tooth which has a through-and-through osseous defect is that incomplete bone healing may be inevitable. This article reviews the use of different barrier membranes for bone regeneration. In addition, the indications, techniques, and prognosis of calcium sulfate in guided bone regeneration are presented.