Initial pattern of angiogenesis and bone formation following lateral ridge augmentation using rhPDGF and guided bone regeneration: an immunohistochemical study in dogs

Objectives: To evaluate (i) the effects of rhPDGF‐BB on localized ridge augmentation using a natural bone mineral (NBM), and (ii) the influence of a collagen membrane (CM) on factor activity. Materials and methods: Chronic‐type alveolar ridge defects (n=4 dogs) were randomly allocated in a split‐mouth design as follows: upper jaw: NBM+rhPDGF‐BB+CM (test) vs. NBM+rhPDGF‐BB (control), and lower jaw: NBM+rhPDGF‐BB+CM (test) vs. NBM+CM (control). After 3 weeks, dissected blocks were prepared for immunohistochemical (angiogenesis – TG) and histomorphometrical analysis [e.g. augmented area (AA), mineralized – (MT), non‐mineralized tissue (NMT) (mm²)]. Results: Lower jaw: TG and mineralization of AA mainly originated from the defect borders. Test sites revealed a pronounced TG antigen reactivity and higher AA and MT values (mean and median). Upper jaw: control sites revealed a dislocation of AA in caudal direction, but also an improved vascularization in the peripheral wound area. While MT values (median) appeared to be comparable in both groups, AA, NMT, and NBM values (mean and median) tended to be higher at test sites. Conclusions: It was concluded that (i) rhPDGF‐BB soak‐loaded on NBM might have the potential to support bone formation at chronic‐type lateral ridge defects, and (ii) the application of CM did not seem to interfere with the factor activity, but ensured a stabilization of the graft particles. To cited this article:
Schwarz F, Ferrari D, Podolsky L, Mihatovic I, Becker J. Initial pattern of angiogenesis and bone formation following lateral ridge augmentation using rhPDGF and guided bone regeneration: an immunohistochemical study in dogs.
Clin. Oral Impl. Res. 21 , 2010; 90–99.     

The combination of purified recombinant human platelet-derived growth factor-BB and equine particulate bone graft for periodontal regeneration

Background: The objective of this study is to evaluate the potential for periodontal regeneration of a critical‐sized defect with the application of recombinant human platelet‐derived growth factor (rhPDGF‐BB) combined with either a particulate equine or a β‐tricalcium phosphate (β‐TCP) matrix. Methods: Critical‐sized intrabony 2‐wall defects were created bilaterally on the distal surface of the second premolar and the mesial surface of the first molar in nine hounds. Twelve defects received rhPDGF‐BB/equine treatment, 12 defects received rhPDGF‐BB/β‐TCP treatment, and the remaining 12 sites served as sham‐surgery controls. The animals were sacrificed after a 10‐week healing period. Results: Clinical healing was uneventful without obvious signs of overt gingival inflammation. Histologic and histomorphometric analyses revealed statistically that there were differences among the three groups in terms of new bone formation (P <0.001). The amount of test material for both rhPDGF‐BB/equine and rhPDGF‐BB/β‐TCP groups was comparable, but the amount of newly formed bone was significantly higher (P <0.01) in favor of the rhPDGF‐BB/equine group. The amount of new cementum formed for the rhPDGF‐BB/equine group (4.8 ± 1.3 mm) was significantly higher (P =0.001) than the sham‐surgery control group (1.7 ± 1.9 mm). Conclusion: Both rhPDGF‐BB/equine and rhPDGF‐BB/β‐TCP have the potential to support the regeneration of the periodontal attachment apparatus.     

Cortical tenting grafting technique in the severely atrophic alveolar ridge for implant site preparation

OBJECTIVES: Alveolar ridge augmentation using intraoral autogenous block grafts to augment localized alveolar ridge defects before implant placement is a predictable method. However, large severely atrophic edentulous segments may require extraoral donor sites. The purpose of this study was to evaluate the effectiveness of using intraoral cortical block grafts in combination with particulate human mineralized allograft, in a "tenting" fashion, to augment large atrophic alveolar ridge defects for implant placement. MATERIALS: This prospective case study evaluated augmentation in 10 consecutive patients with severely resorbed alveolar ridges missing a minimum of 4 adjacent teeth. Before augmentation, all grafted sites were deemed inadequate for placement of a standard 4-mm-diameter implant. Horizontal ridge augmentation was performed using autologous membranous cortical bone grafts from an oral donor site to tent out the soft tissue matrix and periosteum for the adjacent particulate allograft. The ridges were clinically evaluated 4 to 5 months after augmentation, and 42 implants were placed at that time. RESULTS: Implants were successfully placed at all grafted sites 4 to 5 months after the original graft date. Clinical evaluation of the grafted sites upon re-entry revealed uniform ridge anatomy. All edentulous segments had at least 2 implants placed of at least 4.0 mm diameter. In all, 42 implants were placed into grafted sites in the 10 patients. Implants were checked for osseointegration by using a counter torque of 35 N.cm. One implant failed to integrate. Mean follow-up was 22 months after implant placement. All augmented ridges had retained their functional and esthetic integrity at 1 year after original augmentation. CONCLUSION: Tenting of the periosteum and soft tissue matrix using a cortical bone block maintains space and minimizes resorption of the particulate allograft volume. In addition, bridging the cortical blocks with particulate bone avoids unaesthetic ridge defects between cortical block grafts in larger ridge defects. The result was a more uniform and esthetic alveolar ridge, capable of maintaining an implant-supported prosthesis. The technique offers predictable functional and esthetic reconstruction of large-volume defects without extensive amounts of autogenous bone. This offers a superior functional and esthetic result than with either cortical or particulate grafting alone.     

Applicability of equine hydroxyapatite collagen (eHAC) bone blocks for lateral augmentation of the alveolar crest. A histological and histomorphometric analysis in rats

This study assessed the mechanical characteristics, biocompatibility and osteoconductive properties of an equine hydroxyapatite collagen (eHAC) bone block when applied as a bone substitute for lateral augmentation of rat mandible. 96 rats underwent lateral augmentation of the mandible, using two substitute bone blocks (eHAC or Bio-Oss^® spongiosa) or autologous bone grafts. Signs of inflammation, amount of bone formation and ingrowth of bone into the bone blocks were assessed at 1 and 3 months. eHAC blocks were mechanically rigid and could be fixed firmly and easily. Bio-Oss^® spongiosa blocks were brittle and fixation was difficult. eHAC and Bio-Oss^® spongiosa blocks were biocompatible and induced few or no signs of inflammation. Inflammation prevalence between the groups was not statistically different. Bone formation and bone growth into the blocks was significantly higher in eHAC than Bio-Oss^® spongiosa blocks, but lower than in autologous bone grafts (after 1 and 3 months). Regression analysis showed that the autologous bone graft predicted new bone formation at both time points. The eHAC block was only a predictor at 1 month; a trend was found at 3 months. The application of biodegradable membranes was not related to more bone ingrowth.     

Three-dimensional ridge augmentation with xenograft and recombinant human platelet-derived growth factor-BB in humans: report of two cases

The present paper reports on two patients who underwent three-dimensional ridge augmentation using a xenograft in combination with recombinant human platelet-derived growth factor-BB (rhPDGF-BB). Patient 1 received a deproteinized bovine block infused with PDGF and secured to the alveolar crest by two fixation screws to augment the crest horizontally. After 5 months, implants were successfully placed. Patient 2 underwent a vertical ridge augmentation procedure that combined deproteinized bovine bone particles embedded in a collagen matrix soaked in PDGF Three titanium dental implants were placed in each patient 5 months later. Clinical and histologic results showed excellent soft and hard tissue healing. Bone had regenerated throughout the whole area and the xenograft particles were embedded in bone, which presented resorption lacunae close to areas with ongoing bone formation. This indicated that, in augmented areas, intense physiologic remodeling was ongoing. No data exist concerning three-dimensional bone augmentation using PDGF and a xenograft in humans. This report suggests that the use of rhPDGF-BB in combination with a deproteinized bovine graft may have the potential to regenerate large three-dimensional alveolar defects in humans.     

Lateral ridge augmentation using equine‐ and bovine‐derived cancellous bone blocks: a feasibility study in dogs

Objectives: The aim of the present study was to histologically evaluate and compare a new prototype collagen type I/III‐containing equine‐ (EB) and a bovine‐ (BB) derived cancellous bone block in a dog model. Materials and methods: Four standardized box‐shaped defects were bilaterally created at the buccal aspect of the alveolar ridge in the lower jaws of five beagle dogs and randomly allocated to either EB or BB. Each experimental site was covered by a native (non‐crosslinked) collagen membrane and left to heal in a submerged position for 12 weeks. Dissected blocks were processed for semi‐/and quantitative analyses. Results: Both groups had no adverse clinical or histopathological events (i.e. inflammatory/foreign body reactions). BB specimens revealed no signs of biodegradation and were commonly embedded in a fibrous connective tissue. New bone formation and bony graft integration were minimal. In contrast, EB specimens were characterized by a significantly increased cell (i.e. osteoclasts and multinucleated giant cells)‐mediated degradation of the graft material (P<0.001). The amount and extent of bone ingrowth was consistently higher in all EB specimens, but failed to reach statistical significance in comparison with the BB group (P>0.05). Conclusions: It was concluded that the application of EB may not be associated with an improved bone formation than BB. To cite this article:
Schwarz F, Ferrari D, Balic E, Buser D, Becker J, Sager M. Lateral ridge augmentation using equine‐ and bovine‐derived cancellous bone blocks: a feasibility study in dogs.
Clin. Oral Impl. Res. 21 , 2010; 904–912.
doi: 10.1111/j.1600‐0501.2010.01951.x     

Platelet‐Derived Growth Factor Promotes Periodontal Regeneration in Localized Osseous Defects: 36‐Month Extension Results From a Randomized,Controlled, Double‐Masked Clinical Trial

Background: Recombinant human platelet‐derived growth factor (rhPDGF) is safe and effective for the treatment of periodontal defects in short‐term studies up to 6 months in duration. We now provide results from a 36‐month extension study of a multicenter, randomized, controlled clinical trial evaluating the effect and long‐term stability of PDGF‐BB treatment in patients with localized severe periodontal osseous defects. Methods: A total of 135 participants were enrolled from six clinical centers for an extension trial. Eighty‐three individuals completed the study at 36 months and were included in the analysis. The study investigated the local application of β‐tricalcium phosphate scaffold matrix with or without two different dose levels of PDGF (0.3 or 1.0 mg/mL PDGF‐BB) in patients possessing one localized periodontal osseous defect. Composite analysis for clinical and radiographic evidence of treatment success was defined as percentage of cases with clinical attachment level (CAL) ≥2.7 mm and linear bone growth (LBG) ≥1.1 mm. Results: The participants exceeding this composite outcome benchmark in the 0.3 mg/mL rhPDGF‐BB group went from 62.2% at 12 months, 75.9% at 24 months, to 87.0% at 36 months compared with 39.5%, 48.3%, and 53.8%, respectively, in the scaffold control group at these same time points (P <0.05). Although there were no significant increases in CAL and LBG at 36 months among all groups, there were continued increases in CAL gain, LBG, and percentage bone fill over time, suggesting overall stability of the regenerative response. Conclusion: PDGF‐BB in a synthetic scaffold matrix promotes long‐term stable clinical and radiographic improvements as measured by composite outcomes for CAL gain and LBG for patients possessing localized periodontal defects ( ClinicalTrials.gov no. CT01530126).     

Localized ridge augmentation using a block allograft with subsequent implant placement: a case series

The most significant local factors for successful implant placement are the quality and quantity of bone present. Bone loss occurs on a predictable basis following loss of the natural dentition, provided no interceptive therapies are carried out. Restoration of considerable hard tissue defects can be achieved using a variety of techniques, including autogenous blocks and newer methods such as corticocancellous allograft blocks. This report demonstrates successful ridge augmentation using an iliac crest monocortical allograft. Nine patients in need of ridge augmentation for the placement of 16 dental implants were included in this series. Histology from one case after the 6-month healing period demonstrated newly formed woven bone with vascular ingrowth, suggestive of osteoconduction. All grafted sites appeared integrated with clinically visible bleeding following removal of the fixation screw. The mean gain of ridge augmentation at the 6-month reentry was 3.0, 3.2, 3.1, and 3.0 mm, respectively, at the crest and 1, 3, and 5 mm apical to the crest, with individual gains up to 7 mm. Implants were successfully placed in all sites. This method represents an alternative source of block allograft bone for significant alveolar ridge augmentation.     

Tissue engineering with recombinant human platelet-derived growth factor BB for implant site development

Currently, PDGF-BB is FDA-approved for periodontal regeneration as part of a dental bone-filling device only. Although this device uses beta-TCP as the scaffold carrier, there has been considerable clinical interest in combining this growth factor with other bone replacement grafts, particularly bone allografts. This article reports on clinical experiences using rhPDGF-BB with bone allografts for implant site development. After careful evaluation of clinical parameters and consideration of current and emerging evidence, the off-label use of rhPDGF-BB was determined in the following case reports to be consistent with good clinical practice and in the patient's best interest. Clinical, radiographic, and histologic observations from the following selected cases are presented to illustrate treatment outcomes achieved using this combination strategy: ridge preservation for extraction sockets with alveolar wall defects; ridge preservation for extraction sockets minimally invasive techniques; lateral ridge augmentation; and sinus augmentation. All of the cases presented and reviewed were surgically managed using 0.5 ml of 0.3 mg/ml of rhPDGF delivered using a particulate bone allograft (FDBA or DFDBA) as a scaffold. Controlled clinical trials are necessary to establish the relative effectiveness of rhPDGF-BB combined with different mammalian scaffolds for alveolar augmentation.     

Effects of Recombinant Human Bone Morphogenetic Protein‐2 on Vertical Bone Augmentation in a Canine Model

Background: Vertical bone augmentation (VBA) remains unpredictable and challenging for most clinicians. This study aims to compare hard tissue outcomes of VBA, with and without recombinant human bone morphogenetic protein (rhBMP)‐2, under space‐making titanium mesh in a canine model. Methods: Eleven male beagle dogs were used in the study. Experimental ridge defects were created to form atrophic ridges. VBA was performed via guided bone regeneration using titanium mesh and allografts. In experimental hemimandibles, rhBMP‐2/absorbable collagen sponge was well mixed with allografts prior to procedures, whereas a control buffer was applied within controls. Dogs were euthanized after a 4‐month healing period. Clinical and radiographic examinations were performed to assess ridge dimensional changes. In addition, specimens were used for microcomputed tomography (micro‐CT) assessment and histologic analysis. Results: Membrane exposure was found on five of 11 (45.5%) rhBMP‐2–treated sites, whereas it was found on nine of 11 (81.8%) non–rhBMP‐2–treated sites. Within 4 months of healing, rhBMP‐2–treated sites showed better radiographic bone density, greater defect fill, and significantly more bone gain in ridge height (P <0.05) than controls. Experimental hemimandibles exhibited lower rates of membrane exposure and a noteworthy, ectopic bone formation above the mesh in 72% of sites. Results from micro‐CT also suggested a trend of less vertical bone gain and bone mineral density in controls (P >0.05). Under light microscope, predominant lamellar patterns were found in the specimen obtained from rhBMP‐2 sites. Conclusion: With inherent limitations of the canine model and the concern of such a demanding surgical technique, current findings suggest that the presence of rhBMP‐2 in a composite graft allows an increase of vertical gain, with formation of ectopic bone over the titanium mesh in comparison with non–rhBMP‐2 sites.     

Lateral ridge augmentation using an equine flex bone block infused with recombinant human platelet-derived growth factor BB: a clinical and histologic study

This paper reports on a patient who underwent horizontal ridge augmentation using recombinant human platelet-derived growth factor BB (rhPDGF-BB) in combination with a collagenate equine block. Ninety days after the first surgery, 8 mm of new bone was noted on a computed tomography scan, and three 5-mm implants were placed. Histology, performed using confocal laser scanning microscopy, showed a large amount of newly formed bone well characterized with osteon and resorption lacunae, which demonstrated the intense bone remodeling. This study supports the use of rhPDGF-BB in combination with allograft blocks.     

Preservation of ridge dimensions following grafting with coral granules of 48 post-traumatic and post-extraction dento-alveolar defects

Abstract – This prospective clinical analysis reports on the use of coral granules in alveolar ridge preservation procedures in a population of young, growing patients. The sample consisted of 21 patients, 12 females and 9 males, with a mean age of 13.6 years. These 21 patients had 48 dento‐alveolar defects suitable for augmentation with coral granules, and were followed clinically and radiographically for 3–7 years after augmentation. There were two areas of augmentation: 17 defects in the anterior maxilla resulted from traumatic tooth loss, and 31 defects in the posterior maxilla and mandible resulted from the extraction of ankylosed retained primary molars with no permanent succedaneous teeth. Between 1–2 ml of coral granules were implanted into the alveolar bone defects left by the extraction of teeth in both the areas. This was in order to preserve the remaining edentulous ridge from further alveolar ridge resorption. The goal of the procedure was to preserve the alveolus so that in the future, a dental implant could be placed to replace the missing tooth, after jaw growth had stopped, without the need for a bone graft. The coral granules appeared to be totally replaced by the host bone on follow‐up clinical and radiographic examinations. The two areas of the jaws behaved quite differently. In the anterior maxilla, where tooth loss was secondary to trauma, the coral granules restored the alveolar ridges temporarily. However, over the years of follow‐up in this study, the coral granules failed to provide sufficient bone to support the placement of a dental implant without using a bone graft in 14 of the 17 defects or 82.4% of sites. In the posterior maxilla and mandible, where tooth loss was due to the elective removal of ankylosed primary molars, 29 of the 31 defects or 93.5% of sites were successful as they were able to support the placement of an osseo‐integrated dental implant without the use of a bone graft. The alveolar sparing technique was more successful in maintaining an alveolar ridge sufficient for the placement of a dental implant without bone grafting in the posterior maxilla and mandible, where tooth loss was secondary to the elective removal of ankylosed deciduous molars than in the anterior maxilla, where tooth loss was secondary to trauma. Coral granules seem to be more suitable in the posterior maxilla and mandible where there were ankylosed deciduous teeth and congenitally absent permanent teeth than in the traumatized anterior maxilla. In successful sites, coral granules can spare the alveolus from residual ridge atrophy or resorption, obviating the need for a bone graft. This reduces patient morbidity, as a second surgical donor site is avoided because bone graft harvesting is made unnecessary.     

Vertical ridge augmentation by means of deproteinized bovine bone block and recombinant human platelet-derived growth factor-BB: a histologic study in a dog model

The primary objective of this proof-of-principle study was to evaluate the outcome of vertical ridge augmentation in a standardized dog model by combining purified recombinant platelet-derived growth factor (rhPDGF-BB) and a block of deproteinized cancellous bovine bone. The secondary objective was to determine the value of a resorbable barrier membrane to improve the efficacy of the procedure. Six adult foxhounds were committed to bilateral surgical extraction of all four mandibular premolars. A vertical alveolar ridge defect was created at the time of the extractions. Three months later, the artificially created defects were grafted: Group A used a deproteinized bovine bone block in combination with a collagen barrier membrane, group B used a deproteinized bovine bone block infused with rhPDGF-BB only, and group C included a deproteinized bovine bone block infused with rhPDGF-BB, plus a collagen resorbable barrier membrane. After 4 months, the animals were sacrificed. Histologic examination of group B revealed a large amount of newly formed bone, and a large amount of bone-to-implant contact was visible in the areas of bone regeneration extending over the top of the implant cover screw. The results of this preclinical canine study provide proof-of-principle that rhPDGF-BB, used in combination with a deproteinized bovine block without placement of a barrier membrane, has the potential to regenerate significant amounts of new bone in severe mandibular ridge defects. In addition, the results seem to point to the importance of the periosteum as a source of osteoprogenitor cells in growth factor-mediated regenerative procedures.     

Clinical assessment of 40 patients subjected to alveolar distraction osteogenesis

Alveolar bone distraction is a technique used to restore vertical defects in the edentulous alveolar ridge. The gradual growth of bone tissue has a predictable result, allowing the placement of an osseointegrated implant in an ideal position. In this study, the effectiveness of the alveolar distraction technique was verified, using an extraosseous device. The bone augmentation average was 9.5 mm in 40 patients, showing a 92.5% success rate.     

Vertical ridge augmentation by expanded-polytetrafluoroethylene membrane and a combination of intraoral autogenous bone graft and deproteinized anorganic bovine bone (Bio Oss)

Objective: To evaluate, from a histological and histomorphometrical perspective, the efficacy of a 1 : 1 mixture of deproteinized bovine bone mineral (DBBM) and autogenous bone graft associated with an expanded‐polytetrafluoroethylene (e‐PTFE) membrane for vertical ridge augmentation in the human. Material and methods: Seven patients with 10 surgical sites requiring vertical ridge augmentation of partially edentulous lower jaws were included in the study. The vertical augmentation procedure was performed combining a titanium‐reinforced e‐PTFE Gore‐Tex membrane with a composite graft consisting of a 1 : 1 ratio of DBBM (Bio‐Oss) and autogenous bone. Twenty‐seven Branemark implants have been inserted. Eleven biopsies from the regenerated area were analyzed histologically and histomorphometrically. Results: The healing period was uneventful in nine surgical sites. In one site the membrane showed an exposure after 3 months. At the abutment connection, all implants appeared stable and submerged by a hard regenerated tissue clinically similar to bone. The histological analysis showed new bone formation and ongoing remodelling of the autogenous bone and the DBBM particles. Conclusions: The findings from the present clinical and histological study support the use of a 1 : 1 combination of DBBM and autogenous bone chips for vertical ridge augmentation by means of guided bone regeneration techniques. The regenerated bone may lead to proper osseointegration of a dental implant inserted at the time of the regenerative procedure or after a healing period of at least 6 months. DBBM undergoes very slow resorption and substitution with new bone. Furthermore, long‐term clinical studies are needed to confirm the positive effect of DBBM in enhancing the lasting stability of the vertically augmented bone.     

Jawbone enlargement using immediate implant placement associated with a split-crest technique and guided tissue regeneration.

Five patients with sufficient vertical bone height but insufficient bone width for implant placement were chosen for treatment with a split-crest technique combined with guided tissue regeneration. The surgical technique involved splitting the alveolar ridge longitudinally in two parts, provoking a greenstick fracture. A chisel was then used to make a fine cut and spread apart the two cortical plates. Implants were then placed. Implants and defects were covered with expanded polytetrafluoroethylene membranes. Biometrical examination showed a gain in bone width, varying between 1 and 4 mm; maxillary sites showed greater ridge enlargement. Histologic examination showed regeneration of bone tissue between the two portions of the split crest. This membrane technique could be effective and predictable for horizontal ridge augmentation associated with immediate implant placement.     

Efficacy of Cancellous Block Allograft Augmentation Prior to Implant Placement in the Posterior Atrophic Mandible

Background: The present study evaluated the outcome of ridge augmentation with cancellous freeze‐dried block bone allografts in the posterior atrophic mandible followed by placement of dental implants. Materials and Methods: A bony deficiency of at least 3 mm, horizontally, vertically, or both, according to computerized tomography (CT) para‐axial reconstruction served as inclusion criteria. Implants were inserted after a healing period of 6 months. Bone measurements were taken prior to bone augmentation, during implant placement, and at second‐stage surgery. Marginal bone loss and crown‐to‐implant ratio were also measured. Results: Twenty‐nine cancellous allogeneic bone blocks were placed in 21 patients. The mean follow‐up was 37 months. Bone block survival rate was 79.3%. Mean horizontal and vertical bone gains were 5.6 and 4.3 mm, respectively. Mean buccal bone resorption was 0.5 mm at implant placement and 0.2 mm at second‐stage surgery. A total of 85 implants were placed. Mean bone thickness buccal to the implant neck was 2.5 mm at implant placement and 2.3 mm at second‐stage surgery. There was no evidence of vertical bone loss between implant placement and second‐stage surgery. Implant survival rate was 95.3%. All patients received a fixed implant‐supported prosthesis. At the last follow‐up, the mean marginal bone loss was 0.5 mm. The mean crown‐to‐implant ratio was 0.96. Conclusion: Implant placement in the posterior atrophic mandible following augmentation with cancellous freeze‐dried bone block allografts may be regarded as a viable treatment alternative.     

The outcome of intraoral onlay block bone grafts on alveolar ridge augmentations: A systematic review

Aim: The purpose of this study was to systematically review clinical studies examining the survival and success rates of implants placed with intraoral onlay autogenous bone grafts to answer the following question: do ridge augmentations procedures with intraoral onlay block bone grafts in conjunction with or prior to implant placement influence implant outcome when compared with a control group (guided bone regeneration, alveolar distraction, native bone or short dental implants.)? Material and Method: An electronic data banks and hand searching were used to find relevant articles on vertical and lateral augmentation procedures performed with intraoral onlay block bone grafts for dental implant therapy published up to October 2013. Publications in English, on human subjects, with a controlled study design –involving at least one group with defects treated with intraoral onlay block bone grafts, more than five patients and a minimum follow-up of 12 months after prosthetic loading were included. Two reviewers extracted the data. Results: A total of 6 studies met the inclusion criteria: 4 studies on horizontal augmentation and 2 studies on vertical augmentation. Intraoperative complications were not reported. Most common postsurgical complications included mainly mucosal dehiscences (4 studies), bone graft or membrane exposures (3 studies), complete failures of block grafts (2 studies) and neurosensory alterations (4 studies). For lateral augmentation procedures, implant survival rates ranged from 96.9% to 100%, while for vertical augmentation they ranged from 89.5% to 100%. None article studied the soft tissues healing. Conclusions: Survival and success rates of implants placed in horizontally and vertically resorbed edentulous ridges reconstructed with block bone grafts are similar to those of implants placed in native bone, in distracted sites or with guided bone regeneration. More surgical challenges and morbidity arise from vertical augmentations, thus short implants may be a feasible option. Key words:Alveolar ridge augmentation, intraoral bone grafts, onlay grafts, block grafts, dental implants.     

Periodontal regeneration in humans using recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and allogenic bone

BACKGROUND: Purified recombinant human platelet-derived growth factor BB (rhPDGF-BB) is a potent wound healing growth factor and stimulator of the proliferation and recruitment of both periodontal ligament (PDL) and bone cells. The hypothesis tested in this study was that application of rhPDGF-BB incorporated in bone allograft would induce regeneration of a complete new attachment apparatus, including bone, periodontal ligament, and cementum in human interproximal intrabony defects and molar Class II furcation lesions. METHODS: Nine adult patients (15 sites) with advanced periodontitis exhibiting at least one tooth requiring extraction due to an extensive interproximal intrabony and/or molar Class II furcation defect were entered into the study. Eleven defects were randomly selected to receive rhPDGF-BB. Following full-thickness flap reflection and initial debridement, the tooth roots were notched at the apical extent of the calculus, the osseous defects were thoroughly debrided, and the tooth root(s) were planed/prepared. The osseous defects were then filled with demineralized freeze-dried bone allograft (DFDBA) saturated with one of three concentrations of rhPDGF-BB (0.5 mg/ml, 1.0 mg/ml, or 5.0 mg/ml). Concurrently, four interproximal defects were treated with a well accepted commercially available graft (anorganic bovine bone in collagen, ABB-C) and a bilayer collagen membrane. Radiographs, clinical probing depths, and attachment levels were obtained preoperatively (at baseline) and 9 months later. At 9 months postoperatively, the study tooth and surrounding tissues were removed en bloc. Clinical and radiographic data were analyzed for change from baseline by defect type and PDGF concentration. The histologic specimens were analyzed for the presence of regeneration of a complete new attachment apparatus coronal to the reference notch. RESULTS: The post-surgical wound rapidly healed and was characterized by firm, pink gingivae within 7 to 10 days of surgery. There were no unfavorable tissue reactions or other safety concerns associated with the treatments throughout the course of the study. In rhPDGF/allograft sites, the vertical probing depth (vPD) reduction for interproximal defects was 6.42 +/- 1.69 mm (mean +/- SD) and clinical attachment level (CAL) gain was 6.17 +/- 1.94 mm (both P < 0.01). Radiographic fill was 2.14 +/- 0.85 mm. Sites filled with ABB-C had a PD reduction and CAL gain of 5.75 +/- 0.5 and 5.25 +/- 1.71, respectively. Furcation defects treated with rhPDGF/allograft exhibited a mean horizontal and vertical PD reduction of 3.40 +/- 0.55 mm (P < 0.001) and 4.00 +/- 1.58 mm (P < 0.005), respectively. The CAL gain for furcation defects was 3.2 +/- 2.17 mm (P < 0.030). Histologic evaluation revealed regeneration of a complete periodontal attachment apparatus, including new cementum, PDL, and bone coronal to the root notch in four of the six interproximal defects and all evaluable (four of four) furcation defects treated with PDGF. Two of the four interproximal intrabony defects treated with ABB-C and membrane exhibited regeneration. CONCLUSIONS: Use of purified rhPDGF-BB mixed with bone allograft results in robust periodontal regeneration in both Class II furcations and interproximal intrabony defects. This is the first report of periodontal regeneration demonstrated histologically in human Class II furcation defects.