Observations on a new collagen barrier membrane in 16 consecutively treated patients. Clinical and histological findings

BACKGROUND

Space-maintaining capacity, cell disclusive potential, and stability over time are crucial factors to achieving sufficient bone augmentation with membrane barriers. The case series presented here assessed a new collagen barrier used in bone augmentation. Clinically, the healing pattern, especially in cases of secondary healing, was studied.

METHODS

Soft tissue healing was documented by photographs, and the size of the dehiscences calculated by image analysis. The measurements were performed on digitized photographs. During reentry, barrier remnants were dissected and histologically evaluated.

RESULTS

The mean value for dehiscences was 35.5 mm2; all dehiscences healed within 4 weeks after the exposure became evident. The difference was statistically significant between the week 2 and week 6 visits (P = 0.008) for each previously exposed site. The histologic observation of barrier remnants revealed direct apposition of fibrous and bone tissues on the membrane surface.

CONCLUSION

In cases of membrane exposure, gingival dehiscences always disappeared in the following weeks without affecting the healing process. Histologic results showed barrier stability over a 6-month period, promoting bone regeneration.

Alveolar ridge augmentation with rhBMP-2 and bone-to-implant contact in induced bone

The objective of this study was to examine alveolar ridge augmentation following implantation of recombinant human bone morphogenetic protein (rhBMP-2) with an allogeneic freeze-dried demineralized bone matrix (DBM) mixed with autologous blood. A second objective was to evaluate bone-to-implant contact in induced bone. Bilateral surgically created supraalveolar ridge defects in five young adult beagle dogs were implanted with the rhBMP-2-DBM-blood device. Transmucosal dental implants were placed at weeks 8 and 16 postsurgery The animals were euthanized 24 weeks following ridge augmentation. Healing was uneventful in all animals. Radiographic observations indicated substantial bone formation, including regions of radiolucency, at week 8. At week 16, the radiolucencies were generally resolved, and the trabecular structure of the induced bone resembled that of the adjacent residual bone. There were no remarkable differences in radiographic observations between weeks 16 and 24 after ridge augmentation. Histologic analysis revealed dense woven and lamellar induced bone. Any residual DBM appeared remineralized, at least in part. A large portion of the dental implants (approximately 70%) were housed in induced bone with evidence of limited crestal resorption. There was no significant difference in bone density between induced and residual bone, and the levels of bone-to-implant contact were similar (approximately 55%). The rhBMP-2 construct used in this study has a potential to augment alveolar ridge defects. Also, no difference in levels of osseointegration may be expected in induced and residual bone following a two-stage procedure of rhBMP-2-induced ridge augmentation and dental implant placement.

Platelet concentration and its effect on bone formation in calvarial defects: an experimental study in rabbits

STATEMENT OF PROBLEM

The use of the platelet concentration technique is widespread in dental implant surgery. However, its effect or mechanism is not clearly understood.

PURPOSE

This study introduced an animal model for the platelet concentration technique and evaluated its effect on bone formation with natural cancellous bovine bone mineral.

MATERIAL AND METHODS

Adult New Zealand white rabbits were used as the animal model. A density gradient medium was used to obtain a constant platelet count for the preparation of platelet concentrates. In the experimental group, natural cancellous bovine bone mineral with added platelet concentrates was grafted onto critically sized bony defects of the rabbit calvarium. Bone formation in the tissue sections was evaluated with soft x-ray imaging and computer tomography.

RESULTS

The average platelet count of the rabbit platelet concentrates was 1487 x 10(3)/microL (287% concentrated). In all the tested parameters, greater bone densities were obtained in grafts that were combined with platelet concentrates.

CONCLUSION

This study showed that the rabbit is a useful animal model for studying the platelet concentration technique. When combined with grafts of natural cancellous bovine bone mineral, the technique increased bone formation.

Histological and clinical evaluation of 3 different grafting materials for sinus lifting procedure based on 8 cases

BACKGROUND

The reconstruction of edentulous patients with adequate bone volume and density by using dental implants has become a viable treatment option with high predictability. However, initial stabilization is difficult to achieve in the posterior maxillary regions where cortical bone is thin or absent due to severely resorbed alveolar ridges. Maxillary sinus lift procedures applied with various grafting materials enable clinicians to place implant-supported prostheses even in cases with increased pneumatization of the maxillary sinus.

METHODS

The purpose of this study was to evaluate histologically and clinically different grafting materials used in maxillary sinus floor augmentation. Deproteinized bovine bone granules (DBBG), demineralized freeze-dried bone powder (DFBP), and porous hydroxyapatite (PHA) were used as grafting materials. A total of 19 implants in 8 patients were placed into grafted sites. In 3 patients, a 2-stage approach was used wherein implants were inserted after a 6-month healing period following a sinus lift procedure. Specimens were taken with a trephine drill, and the site of the specimen was enlarged to accept an implant. For the remaining cases, a 1-stage approach, which included sinus lifting and implant placement, was used and bone biopsies were taken during the uncovering stage. After 6 months of healing, fixed prosthetic restorations were fabricated.

RESULTS

The healing period progressed without any complications, and all implants were loaded. The mean functioning time was 12 months, varying from 9 to 24 months.

CONCLUSION

The results indicate that DFBP resorbs earlier than PHA and DBBG in sinus lift procedures.

Periodontal healing in humans using anorganic bovine bone and bovine peritoneum-derived collagen membrane: a clinical and histologic case report

The authors report the clinical and histologic data on the healing of a severe periodontal lesion obtained in a one-walled intrabony defect using anorganic bovine bone under a bovine peritoneum-derived collagen membrane. Eight months after surgery, a bone-like tissue replaced the lost tissues. A biopsy of this tissue was carried out. In the part of the specimen closer to the residual bony wall of the original defect, anorganic bone particles (ABP) appeared to be surrounded by a layer of newly formed bone; its osteocyte lacunae were colonized by osteocytes from the host, and actively secreting osteoblasts were observed in many microscopic fields. No resorption phenomena were observed in the ABP Newly formed cementum with actively secreting cementoblasts was present on the tooth surface, and well-oriented fibers inserting in both newly formed cementum and bone were observed. In an area far from residual bone, all ABP did not appear to be surrounded by newly formed bone. Osteocytic lacunae appeared not to be colonized by cells, and ABP was surrounded by dense connective tissue without osteoblasts near the grafted particles. A very limited amount of newly formed bone, without relations with ABP, was observed close to the root surface. From a clinical point of view, anorganic bone in association with a collagen membrane can be effective in the treatment of bony defects characterized by an unfavorable architecture. From a histologic point of view, the clinical appearance of bone regeneration is not always confirmed in the part of the defect far from the bony walls.

Demineralized bone matrix, bone morphogenetic proteins, and animal models of spine fusion: an overview

Preclinical investigations on the use of bone morphogenetic proteins (BMP) in the spine have yielded promising results. This has led to the preliminary introduction of these growth factors in controlled clinical trials. Initial data made available suggest that these differentiating factors will play a major role in the treatment of spinal disorders in the future. This article reviews key preclinical studies and their results that formed the basis for introduction into clinical trials. Non-primate and non-human primate models of spine fusion with BMP are reviewed objectively, and important issues regarding carrier, dose, and site of implantation are discussed. Finally, exciting new gene therapy research is discussed, with comments made on its applicability for the future.

Combined implantation of particulate dentine, plaster of Paris, and a bone xenograft (Bio-Oss) for bone regeneration in rats

The purpose of this study is to assess the combination of particulate dentine and plaster as bone substitute material in calvarial bone defects in rats, and to compare it with a bone xenograft (Bio-Oss).

MATERIAL AND METHODS

Forty rats were assigned randomly to five groups and each group was further divided into two subgroups, 8 and 16 weeks after implantation. The defect was filled with different graft materials in each group: Group 1, defects were filled with particulate dentine and plaster using a 2:1 ratio; Group 2, defects were filled with particulate dentine; plaster, and Bio-Oss using a 2:1:1 ratio; Group 3, defects were filled with plaster and Bio-Oss using a 1:1 ratio; Group 4, defects were filled with Bio-Oss only; and Group 5, untreated control defects. Histological sections and histomorphometric analysis of defects were obtained at 8 and 16 weeks postoperatively.

RESULTS

New bone formation was highest in Group 4, followed by Group 3, than Group 2, Group 1, and finally the control group.

CONCLUSION

The combination of particulate dentine and plaster is an alternative bone substitute, although it is less effective than Bio-Oss.

Clinical applications of bone graft substitutes in spine surgery: consideration of mineralized and demineralized preparations and growth factor supplementation

Bone graft substitutes may be broadly classified as mineralized and demineralized preparations. This article reviews the basic science and biology underlying each preparation. A review of the clinical and experimental applications of each preparation follows. The text concludes with a review of growth factors as biological supplements.

Mandibular reconstruction with a prefabricated vascularized bone graft using recombinant human osteogenic protein-1: an experimental study in miniature pigs. Part I: Prefabrication

Osteogenic protein-1 (rhOP-1), also called bone morphogenetic protein-7 (BMP-7), is osteoinductive. It may be possible to reconstruct a mandible by local application of rhOP-1. However, in tumour patients this can be impossible due to scars or preceding radiotherapy. Usually vascularized bone grafts are indicated. The aim of this study was to prefabricate a vascularized bone graft in the latissimus dorsi muscle for microsurgical transplantation. In nine minipigs 600 microgram rhOP-1 were used with 8 ml xenogenic bone mineral (BioOss, Geistlich, Waldenburg, Germany) as a carrier and inserted into a pouch prepared in the M. latissimus dorsi. After 6, 12, and 24 weeks the grafts were harvested. The results were evaluated using computed tomography, histology, macro- and microangiography. A high yield of newly formed bone was obtained on the osteoconductive scaffold of the xenogenic bone. It was possible to create a vascularized osseous graft in the given shape of the BioOss blocks. In cross-sections, 68% of the scaffold was coated with new bone. The amount of new bone did not differ between the prefabrication times. Bone overgrowth was 2.1% of the graft volume. In conclusion, this study has shown that it can be possible to prefabricate a neomandible within a muscle graft, which then could be transferred for microvascular reconstruction of the mandible. Further research is required before this technique can be refined for clinical use.

Evaluation following functional loading of titanium fixtures placed in ridges augmented by deproteinized bone mineral. A human case study

The aim of this investigation was to clinically evaluate the periimplant tissues of titanium fixtures, placed in regions augmented using deproteinized bone mineral, after initial functional loading. The original material included 18 individuals (mean age 71+/-9 years) treated using a graft material, Bio-Oss (6 Patients), or Bio-Oss+autogenous bone mixture (12 patients) for alveolar ridge augmentation. 6 titanium fixtures were placed at the time of ridge augmentation. 46 fixtures were placed at a second surgical stage, median 9.5 months after augmentation. Augmentation included crest width (26 fixtures), crest height and width (12 fixtures) and sinus floor lift (14 fixtures) procedures. In addition, 16 fixtures were placed in regions of adequate bone volume. Reconstructions were placed and patients were recalled on a yearly basis. After 4-6.5 years of functional loading, the reconstructions were removed and assessments of fixture stability and periimplant mucosal conditions were made. At this time, 3 patients (13 fixtures) were lost to follow-up (1 deceased, 1 declined to participate, and 1 too ill to attend). In the remaining 15 patients, 7 fixtures were lost due to osseo-disintegration, 2 in one patient in the mandible, and 5 in a second patient in the maxilla. Both individuals were smokers. The remaining 32 fixtures were clinically stable. Periimplant mucosa was healthy with a mean modified sulcular bleeding index of 0.1+/-0.2 and a mean probing depth of 1.5+/-1.1 mm. Radiographic evaluation showed alveolar bone levels at or above the level of the first fixture thread. There were no perifixtural radiolucencies. The survival rate, which coincided with success rate, for fixtures placed in conjunction with ridge augmentation using deproteinized bone mineral was 100% for non-smokers and 43% for smokers after 4-6.5 years of functional loading. No fixture loss occurred in non-augmented areas.

Sinus floor elevation using a bovine bone mineral (Bio-Oss) with or without the concomitant use of a bilayered collagen barrier (Bio-Gide): a clinical report of immediate and delayed implant placement

Xenografts have been used extensively, either alone or in combination with autogenous bone, in sinus floor elevation techniques. However, controversy exists regarding the need to cover the lateral osteotomy site with a membrane. Also, the healing period before loading remains undefined when machined-surface implants are placed. Twenty-nine patients showing reduced bone volume in the posterior maxilla had 61 Brånemark System implants placed in 30 sinuses augmented with a lateral osteotomy approach. Sinuses grafted with Bio-Oss and covered with a collagen membrane Bio-Gide (M+) received 29 implants, while grafted but uncovered sites (M-) received 32 implants. An immediate procedure was followed to place 41 implants and a staged procedure was used for 20 implants. Abutment connection was made in 2 distinct postoperative periods: 6 to 9 months and over 9 months. The patients were followed for an average of 22.4 months. The survival rate of the implants was dependent on the postoperative healing time and membrane presence. In case of the immediate procedure and in M- sites, when residual bone height was less than 5 mm, more failures occurred when the loading was done at 6 to 9 months than after 9 months. No failures occurred in the M- series when a staged approach was followed. The overall survival rate was 78.1% for the M- sites and 93.1% for the M+ sites. No failures occurred (0/35) in the control implants placed in adjacent native bone. Implant survival rate was related to the quality of the reconstructed cortical plate and to implant length. The concomitant use of a collagen barrier to cover the osteotomy site, when machined-surface implants were used in sinus grafting, seemed to improve the quality of the graft healing and survival rate of the implants loaded between 6 and 9 months after placement.

Absorbable versus nonabsorbable membranes and bone grafts in the treatment of ligature-induced peri-implantitis defects in dogs: a histometric investigation

The purpose of this study was to histometrically evaluate an absorbable collagen membrane (Bio-Gide) and a nonabsorbable polytetrafluoroethylene membrane (PTFE), associated with or without bone grafts, regarding "re-osseointegration" after treating ligature-induced peri-implantitis defects in dogs. All mandibular premolars were removed from five 2-year-old mongrel dogs. After 3 months of healing, 3 titanium implants were placed on each side of the mandible. Experimental peri-implantitis was induced with ligatures after abutment connection. Ligatures and abutments were removed after 1 month and the bone defects were randomly assigned to one of the following treatments; debridement alone (DB), debridement plus PTFE membrane associated with mineralized bone graft (Bio-Oss) (GBR+BG-I), debridement plus collagen membrane (Bio-Gide) associated with mineralized bone graft (GBR+BG-II), debridement plus PTFE membrane (GBR-I), debridement plus collagen membrane (GBR-II), or debridement plus mineralized-bone graft (BG). The dogs were sacrificed after 5 months. Data analysis did not reveal significant differences among the treatments regarding the percentage of bone-to-implant contact ("re-osseointegration") within the limits of the threads of the implant (P = .997). Thus, in the treatment of peri-implantitis, debridement alone as well as grafting alone had the same effect as did either membrane.

The use of plasma-rich growth factors (PRGF) in oral surgery

The therapeutic objective of utilizing growth factors in oral surgery is to improve upon the body's regenerative capacity. In many situations, the unaided regeneration process is insufficient to allow complete repair of both bone and soft tissues. This article presents two clinical cases that describe different applications of growth-factor preparation applied at the surgical site in order to stimulate regeneration of osseous and epithelial tissues. Both clinical cases demonstrate the therapeutic effectiveness of utilizing the described technique for the incorporation of plasma-rich growth factors as an adjuvant in regenerative procedure.

An unexpected outcome during testing of commercially available demineralized bone graft materials: how safe are the nonallograft components?

STUDY DESIGN

Radiographic and histologic analyses of commercially available bone graft materials were performed.

OBJECTIVE

To compare the osteoinductive efficacy of commercially available demineralized bone matrix material.

SUMMARY OF BACKGROUND DATA

The relative in vivo bone formation and toxicology of the nonallograft components the make up various commercially available demineralized bone matrix products are not known.

METHODS

An in vivo bone formation model was used in 30 athymic rats. Six different bone grafting materials were tested in subcutaneous and intermuscular locations. After 4 weeks, radiographic and histologic testing of bone formation was performed.

RESULTS

Eight of nine rats implanted with Grafton demineralized bone matrix products died 1 to 4 days after implantation of the bone graft material. None of the remaining 10 animals implanted with the four other grafting materials died. The experiment was modified and completed with a lower dose of bone graft material. Pathologic analysis indicated that the cause of death was hemorrhagic necrosis of the kidneys, most likely caused by a toxic effect on the glomeruli and tubules. A possible causative factor may have been the glycerol in the graft material.

CONCLUSIONS

Although the volume of Grafton product per kilogram of body weight used in this study was approximately eight times the maximum volume used in humans, the authors believe that this data must be reported because this product is used substantially in clinical settings. In addition, the osteoinductive performance and relative safety of the nonallograft components in all commercially available demineralized bone grafts are not known.

Dose-dependent toxicity of a commercially available demineralized bone matrix material

STUDY DESIGN

A relative risk assessment was performed to determine the safety of three commercially available Grafton demineralized bone matrix quantities used in athymic rats.

OBJECTIVE

To evaluate the possible dose-dependent adverse effects of a commercially available demineralized bone matrix containing glycerol.

SUMMARY OF BACKGROUND DATA

Commercially available Grafton demineralized bone matrix contains glycerol. The toxic effects of glycerol leading to acute renal failure have been documented. The toxicity of this glycerol-containing substance in higher doses has not been reported.

METHODS

Three doses of Grafton putty were implanted in the upper hind limb muscles of athymic nude rats. The rats were observed for adverse effects and early death. Histologic studies were performed.

RESULTS

All eight of the rats implanted with the highest dose of Grafton putty (0.008 mL/g) died, five of them within 12 hours of implantation and three in 48 to 72 hours. One rat with the intermediate dose (0.004 mL/g) died within 12 hours of implantation. By 72 hours after implantation, three of the six rats (50%) with the intermediate dose had died. All six of the rats receiving the lowest dose (0.002cc/g) survived. The median lethal dose of Grafton putty in athymic rats was estimated to be 0.00469 mL/g body weight. Histologic analysis of the animals that received the high dose showed acute tubular necrosis, probably secondary to rhabdomyolysis.

CONCLUSIONS

In athymic rats, large amounts of Grafton putty lead to death in a dose-dependent manner. Because the median lethal doses of Grafton putty (0.00469 mL/g) and glycerol (0.00442 mL/g) are comparable, a potential source of toxicity is the glycerol contained in the material. The results of this study suggest that high doses have the potential to cause acute renal failure. The authors suggest that clinical usage of Grafton putty in humans should be limited to no more than 2 mL/kg body weight of this material.

Human histologic and histomorphometric analysis comparing OsteoGraf/N with PepGen P-15 in the maxillary sinus elevation procedure: a case report

The use of the anorganic bovine bone mineral OsteoGraf/N combined with demineralized freeze-dried bone allograft has received widespread use in sinus elevations. This composite graft material has proven to be suitable, predictable, and successful for the placement and integration of endosseous implants in the edentulous, atrophic maxilla. In this case study, the current materials and accepted methodology were compared with the latest tissue-engineered bone replacement graft material, PepGen P-15. PepGen P-15 is a combination of OsteoGraf/N and a synthetic peptide (P-15) that mimics the cell-binding domain of Type-I collagen responsible for cell migration, differentiation, and proliferation. The radiographic, histologic, and histomorphometric evaluations of the sinus grafted with PepGen P-15 showed enhanced bone formation within a shorter time interval compared with the composite graft material of OsteoGraf/N and demineralized freeze-dried bone allograft.

A new sinus lift technique in conjunction with placement of 265 implants: a 6-year retrospective study

A new surgical crestal approach for implant placement in deficient alveolar ridges is presented. Drills of different and increasing lengths allow the surgeon to approach the membrane without risk of tearing it. The study is supported by 265 cases and a 6-year follow-up period (1994-1999). Implants that were 13 and 15 mm in length were inserted, respectively, in 205 and 60 cases. The alveolar ridge height varied between 4 and 10 mm. All implants were HA-coated and had a 3.25-mm diameter. The results of this investigation suggest that this is a reliable and predictable technique for the prosthetic rehabilitation of the maxillary posterior regions in the presence of anatomical restrictions for implant placement.

Postextraction ridge preservation using a synthetic alloplast

Ridge preservation is the prevention of the 40% to 60% jaw-bone atrophy that normally takes place 2 to 3 years postextraction and continues at a rate of 0.25% to 0.5% per year until death. It is achieved by the immediate grafting of the extraction socket with or without the use of an immediate implant. It offers the dentist the ability to preserve the alveolar ridge for future implant and restorative dentistry, to achieve anterior esthetics, and to prevent postoperative pain and bleeding. The practice of ridge preservation involves advanced extraction therapy and replacement therapy.

Effects of single-dose versus fractionated irradiation on the suppression of heterotopic bone formation--an animal model-based follow-up study in rats

The histological and enzymatic effects of single-dose irradiation of 7 Gray (Gy) versus fractionated irradiation of 5 x 2 Gy on the suppression of heterotopic ossification were examined over a period of 60 days in adult male Wistar rats (n = 57). The standardized osteogenesis model system in rats 19, 10, 11, 16, 19] was used for this purpose. The course of developing ossifications was documented quantitatively and qualitatively by means of quantitative computed tomography/osteodensitometry and digital luminescence radiography. Assessment of the activities of the enzymes alkaline and acid phosphatase throughout the experiment as well as characterization of the isoenzyme of alkaline phosphatase (AP) in connection with histological observations displayed a metaplasia of the ingrowing connective tissue into bone-typical cells during osteoinduction. Thus, the increase of AP is the first sign of a functional transformation of mesenchymal stem cells into chondroid bone cells. The increase in the acid phosphatase level with a maximum of activity between the 15th and 30th day (according to the respective treatment group) is highly suggestive of a remodeling process paralleling incipient chondroclast and osteoclast activity. In the animal groups undergoing irradiation, the above-mentioned increase of enzymes occurred after a delay. Furthermore, the maximum values observed were lower than those in the group not undergoing irradiation. Both findings were more manifest in the animal group which underwent 5 x 2 Gy of radiation than in the group which underwent single-dose irradiation of 7 Gy. Radiation suppresses matrix-induced osteogenesis. The histological and enzymatic course of this process was unchanged in the animals which did not undergo irradiation. However, it was quantitatively reduced and accompanied by a retardation of osteogenesis. Both effects were again reduced with fractionated irradiation of 5 x 2 Gy, which is theoretically dose-equivalent to a 1 x 7 Gy application. Histological examinations revealed damage to the migratory, proliferating mesenchymal stem cell population by irradiation doses which had relatively small effects on preosteoblasts, osteoblasts, chondroblasts and other specialized cell forms. Therefore, it may be concluded that the smaller degree of heterotopic ossification in the irradiated groups was due to damage of and a decrease in the number of mesenchymal stem cells at the implant site. Our results stress the necessity of instituting postoperative irradiation therapy as early as possible to prevent heterotopic ossification. In view of experimentally proven better effects, fractionated irradiation has to be preferred to a dose-equivalent single-dose radiation, especially considering the fewer side-effects noted with fractionated irradiation.

Histologic analysis of implant sites after grafting with demineralized bone matrix putty and sheets

Grafting to restore lost alveolar bone is frequently used to enable placement of endosseous implants and improve cosmesis. Conflicting reports concerning the osteoinductivity of demineralized bone matrix (DBM) and historical use of synthetic bone graft substitutes has limited the use of DBM in oral and maxillofacial applications. Implant placement after bone grafting provides the unique opportunity to biopsy and histologically evaluate new bone formation. Bone grafting of the mandible or maxilla was performed to fill extraction sockets and restore ridge structures in a consecutive series of eight patients. DBM prepared as malleable putty (Grafton DBM Putty) or flexible sheets (Grafton DBM Flex) was used. Biopsies were taken at reentry, and histologic analysis determined the amount and quality of regenerated bone. Extensive new bone formation and minimal residual bone graft matrix were observed at an average of 5 months postoperative. The pattern of new bone maturity and remodeling varied by patient and the time in situ. Putty and Flex regenerated excellent bone height and width for the placement of dental implants, were easy to handle intraoperatively, and readily conformed to bony defects.

Alveolar ridge augmentation with Bio-Oss: a histologic study in humans

The aim of the present study was to investigate the healing of alveolar ridge defects augmented with cancellous bovine bone mineral. In six partially edentulous patients, bone augmentation was necessary prior to implant placement because of severe alveolar ridge resorption. The defect sites, all located in the maxilla, were filled with Bio-Oss and covered with the resorbable collagen membrane Bio-Gide. Biopsies were obtained from the defect sites 6 to 7 months following grafting and were processed for ground sectioning. The histologic analysis revealed that the Bio-Oss particles occupied 31% of the total biopsy area. An intimate contact between woven bone and Bio-Oss was detected along 37% of the particle surfaces. A mixed type of bone was found; it contained woven bone and parallel-fibered bone, which demonstrates features of remodeling activity. Signs of resorption of the grafting material were observed in the histologic sections, which indicates that the material takes part in the remodeling process. It is suggested that Bio-Oss may be a very suitable material for staged localized ridge augmentation in humans.

A comparative study on the use of Bio-Oss and enamel matrix derivative (Emdogain) in the treatment of periodontal bone defects

The aim of the study was to evaluate the clinical and radiographic outcome following two different techniques of periodontal bone defects treatment. The study included 24 generally healthy subjects with advanced periodontitis. The patients were divided into two equal groups, according to the method applied. In the first group, a bovine-derived hydroxyapatite xenograft (Bio-Oss) combined with a resorbable collagen membrane (Bio-Gide) was used. The other group was treated with enamel matrix derivative (Emdogain). Clinical and radiographic examinations were performed prior to and 1 yr after surgery. The following parameters were evaluated: plaque index, gingival index, probing pocket depth, clinical attachment level, gingival recession, radiographic defect depth, and defect width. All clinical and radiographic parameters (except plaque index and gingival recession) were significantly reduced after treatment in both groups. No differences were revealed between the two groups of patients in examined parameters after treatment. The results demonstrated that the treatment of periodontal bone defects with both techniques leads to similar and significant improvements in clinical and radiographic parameters.

Efficacy of implant placement after bone grafting for three-dimensional reconstruction of the posterior jaw

A series of 21 men and 41 women received grafts resulting in mean faciolingual augmentation of 5.1 mm and mean vertical augmentation of 3.9 mm. In most patients, bone was obtained from the iliac crest. At the time of implant placement, the bone at the site was restored anatomically to type B in 50 patients and to type C in 12. The patients received from one to ten posterior implants, which were placed simultaneously with (n = 5) or approximately 6 months after grafting. All of the implants were loaded, with the follow-up ranging from 12 to 96 months (mean 37.3 months). Ceramometal restorations were ultimately used in all patients. Five patients suffered partial graft loss at a total of 21 implants, of which five (24%) failed. The total failure rate for implants placed in patients who received sinus + veneer grafts was 4% (9/222). In patients who received sinus and J grafts, the final implant failure rate was 2%. All implants placed in anteroposterior J grafts and mandibular grafts were successful. Overall, including replacement implants, the failure rate was 7% (23/329). Posterior implants can be placed after graft reconstruction with a success rate similar to that obtained without grafting, thereby improving the function and esthetic outcome.