Objective: To histologically evaluate the effects of a novel human recombinant amelogenin (rAmelX) on periodontal wound healing/regeneration in intrabony defects. Method and materials: Intrabony defects were surgically created in the mandible of three minipigs. Twelve defects were randomly treated with either rAmelX and carrier (test group) or with the carrier only (control group). At 3 months following reconstructive surgery, the animals were euthanized, and the tissues histologically processed. Thereafter, descriptive histology, histometry, and statistical analyses were performed. Results: Postoperative clinical healing was uneventful. At the defect level, no adverse reactions (eg, suppuration, abscess formation, unusual inflammatory reaction) were observed with a good biocompatibility of the tested products. The test group yielded higher values for new cementum formation (4.81 ± 1.17 mm) compared to the control group (4.39 ± 1.71 mm) without reaching statistical significance (P = .937). Moreover, regrowth of new bone was greater in the test compared to the control group (3.51 mm and 2.97 mm, respectively, P = .309). Conclusions: The present results provided for the first-time histologic evidence for periodontal regeneration following the use of rAmelX in intrabony defects, thus pointing to the potential of this novel recombinant amelogenin as a possible alternative to regenerative materials from animal origins. Keywords: amelogenin, enamel matrix derivative, intrabony defects, periodontal regeneration, recombinant, wound healing

Bone exostosis is defined as a benign overgrowth of bone tissue of unclear origin. Rarely, bone exostosis might develop following soft tissue graft procedures like mucogingival surgical interventions (eg, FGG or subepithelial CTG). This aberration has been mainly associated with surgical trauma or fenestration of the periosteum but is still a matter of debate. The present paper (1) presents a clinical case with clinical, radiographic, and histologic findings at 30 years following application of an FGG to increase the gingival width and (2) provides a short literature review on this particular clinical condition. At the clinical examination, the FGG was firm to palpation, and the 3D images showed an area of increased radiopacity. Histologic analysis revealed localized thickening of the bone with an overlaying connective tissue covered by keratinized epithelium. The bony tissue was vital, had a convex shape, and contained many osteocytes and resting lines, demonstrating some moderate signs of bone remodeling. The connective tissue and keratinized epithelium displayed a regular thickness without any signs of inflammation. Taken together, the histologic findings failed to reveal any pathologic signs except for the presence of vital bone formed outside the bony envelope. It can be concluded that: (1) the development of a bone exostosis following a mucogingival procedure is a rare clinical sequela of uncertain etiology, and (2) surgical removal of the exostosis may be indicated accordingly with patient symptoms.

Bovine-derived bone mineral demonstrated good osteoconductive properties as grating material for maxillary sinus floor elevation, but the long-term behavior of this material has not been reported. The purpose of this report was to analyze and compare histomorphometric measurements of new bone, bone graft, and medullar spaces 6 months, 12 months, and 20 years after grafting. In the grafted area, the amount of mineralized bone was 16.96% at 6 months, 22.53% at 12 months, and 22.05% at 20 years, respectively. The amount of bovine-derived bone mineral ranged from 35.87% to 4.85% in the same period. The volume of the newly formed mineralized bone does not increase over time, conversely to nonmineralized bone. Keywords: bovine bone, histomorphometry, long term, maxillary sinus grafting

Background: Due to its advantageous physical, biological, and esthetic properties as well as its resistance to corrosion, zirconia as a biomaterial to replace missing tooth roots has been the focus of great interest and may become a reliable alternative to titanium implants. Aim: To present and discuss the preclinical data available on osseointegration of zirconia implants placed in the jawbone. Results: A great number of preclinical studies on zirconia implants with histologic and histomorphometric data are available. Zirconia implants were tested with different implant dimensions and designs, different surface treatments (e.g. machined, sandblasted, acid-etched, alkaline-etched, fusion-sputtered, selective infiltration-etched, powder injection molding, laser-treated, plasma-treated, microgrooved), in different species (i.e., rabbit, monkey, sheep, miniature pig, rat, dog) and different anatomical locations (i.e. tibia, femur, pelvis, maxilla, mandible), under different loading conditions, and with different observation periods (i.e. 1-56 weeks). Taken together, the boneto- implant (BIC) values reported in the literature for zirconia implants placed in the jawbone range from 18% to 89% with many values in the order of 50%-75%. All in all, most preclinical studies and reviews concluded that the BIC values did not reveal statistically significant differences between zirconia and titanium implants. Furthermore, most studies and most reviews come to the conclusion that modified zirconia surfaces have higher BIC values than machined ones. Conclusions: Most preclinical studies and reviews conclude that zirconia and titanium implants have similar BIC values. Nevertheless, the survival and success rates of zirconia implants documented in clinical studies are dependent on the implant type/system and somewhat inferior to those of titanium implants. More solid, long-term clinical data on zirconia implants are needed and differences between implant systems and surgical procedures need to be evaluated. Keywords: Zirconia, dental implant, osseointegration, bone-to-implant contact

Purpose: Collagen barrier membranes were first introduced to regenerative periodontal and oral surgery to prevent fast ingrowing soft tissues (ie, epithelium and connective tissue) into the defect space. More recent attempts have aimed at combining collagen membranes with various biologics/growth factors to speed up the healing process and improve the quality of regenerated tissues. Recently, a new formulation of enamel matrix derivative in a liquid carrier system (Osteogain) has demonstrated improved physico-chemical properties for the adsorption of enamel matrix derivative to facilitate protein adsorption to biomaterials. The aim of this pioneering study was to investigate the use of enamel matrix derivative in a liquid carrier system in combination with collagen barrier membranes for its ability to promote osteoblast cell behavior in vitro. Materials and Methods: Undifferentiated mouse ST2 stromal bone marrow cells were seeded onto porcine-derived collagen membranes alone (control) or porcine membranes + enamel matrix derivative in a liquid carrier system. Control and enamel matrix derivative- coated membranes were compared for cell recruitment and cell adhesion at 8 hours; cell proliferation at 1, 3, and 5 days; and real-time polymerase chain reaction (PCR) at 3 and 14 days for genes encoding Runx2, collagen1alpha2, alkaline phosphatase, and bone sialoprotein. Furthermore, alizarin red staining was used to investigate mineralization. Results: A significant increase in cell adhesion was observed at 8 hours for barrier membranes coated with enamel matrix derivative in a liquid carrier system, whereas no significant difference could be observed for cell proliferation or cell recruitment. Enamel matrix derivative in a liquid carrier system significantly increased alkaline phosphatase mRNA levels 2.5-fold and collagen1alpha2 levels 1.7-fold at 3 days, as well as bone sialoprotein levels twofold at 14 days postseeding. Furthermore, collagen membranes coated with enamel matrix derivative in a liquid carrier system demonstrated a sixfold increase in alizarin red staining at 14 days when compared with collagen membrane alone. Conclusion: The combination of enamel matrix derivative in a liquid carrier system with a barrier membrane significantly increased cell attachment, differentiation, and mineralization of osteoblasts in vitro. Future animal testing is required to fully characterize the additional benefits of combining enamel matrix derivative in a liquid carrier system with a barrier membrane for guided bone or tissue regeneration. Keywords: bone graft, emdogain, enamel matrix derivative, enamel matrix proteins, periodontal regeneration

Reducing the need for a connective tissue graft by using an efficacious biomaterial is an important task for dental professionals and patients. This experimental study aimed to test the soft tissue response to a volume-stable new collagen matrix. The device demonstrated good stability during six different time points ranging from 0 to 90 days of healing with no alteration of the wound-healing processes. The 90-day histologic specimen demonstrates eventual replacement of most of the matrix with new connective tissue fibers.

Purpose: Autologous bone is used for augmentation in the course of oral implant placement. Bone grafts release paracrine signals that can modulate mesenchymal cell differentiation in vitro. The detailed genetic response of the bone-derived fibroblasts to these paracrine signals has remained elusive. Paracrine signals accumulate in bone-conditioned medium (BCM) prepared from porcine cortical bone chips. Materials and Methods: In this study, bone-derived fibroblasts were exposed to BCM followed by a whole genome expression profiling and downstream quantitative reverse transciptase polymerase chain reaction of the most strongly regulated genes. Results: The data show that ADM, IL11, IL33, NOX4, PRG4, and PTX3 were differentially expressed in response to BCM in bone-derived fibroblasts. The transforming growth factor beta (TGF-β) receptor 1 antagonist SB431542 blocked the effect of BCM on the expression of the gene panel, except for IL33. Conclusion: These in vitro results extend existing evidence that cortical bone chips release paracrine signals that provoke a robust genetic response in mesenchymal cells that is not exclusively mediated via the TGF-β receptor. The present data provide further insights into the process of graft consolidation. Keywords: ADM, bone-conditioned medium, bone supernatant, IL11, IL33, NOX4, PRG4, PTX3, SB431542

Dental implant surface technology has evolved from a relatively smooth machined implant surface for osseointegration to more roughened osteoconductive surfaces. Recent studies suggest that peri-implant soft tissue inflammation with progressive bone loss (ie, peri-implantitis) is becoming a prevalent condition. One possibility that could explain such a finding is that more bacterial plaque forms on the roughened implant and abutment surfaces, which may result in the peri-implant inflammation in the soft tissues. This study compared 36 tissue-level implants with a machined transmucosal collar to 36 implants with a relatively roughened (SLActive) transmucosal surface in the dog. The implants were evaluated histologically and histomorphometrically after 3 and 12 months of loading. The results demonstrated that the connective tissue contact was similar between the two implant types but that the junctional epithelium and biologic width dimensions were greater around the implants with the machined collars. Interestingly, the amount of inflammation was similar between the two implant types. Slightly more bone formation and more mature collagen formation occurred around the implants with the roughened collars compared to the implants with machined collars. These results suggested that even if more plaque biofilm forms on the implants with the roughened SLActive surface compared to the machined surface, there is no biologic consequence related to the amount of inflammation or bone loss. In fact, the roughened surface promoted bone formation (was more osteoconductive) and more mature soft collagenous connective tissue.

Purpose: Autografts are considered to support bone regeneration. Paracrine factors released from cortical bone might contribute to the overall process of graft consolidation. The aim of this study was to characterize the paracrine factors by means of proteomic analysis. Materials and Methods: Bone-conditioned medium (BCM) was prepared from fresh bone chips of porcine mandibles and subjected to proteomic analysis. Proteins were categorized and clustered using the bioinformatic tools UNIPROT and PANTHER, respectively. Results: Proteomic analysis showed that BCM contains more than 150 proteins, of which 43 were categorized into "secreted" and "extracellular matrix." Growth factors that are not only detectable in BCM, but potentially also target cellular processes involved in bone regeneration, eg, pleiotrophin, galectin-1, transforming growth factor beta (TGF-β)-induced gene (TGFBI), lactotransferrin, insulin-like growth factor (IGF)-binding protein 5, latency-associated peptide forming a complex with TGF-β1, and TGF-β2, were discovered. Conclusion: The present results demonstrate that cortical bone chips release a large spectrum of proteins with the possibility of modulating cellular aspects of bone regeneration. The data provide the basis for future studies to understand how these paracrine factors may contribute to the complex process of graft consolidation. Keywords: autograft, bone regeneration, conditioned medium, paracrine, proteomics, secretome, supernatant

The aim of this study was to evaluate in humans the amount of new bone after sinus floor elevation with a synthetic bone substitute material consisting of nanocrystalline hydroxyapatite embedded in a highly porous silica gel matrix. The lateral approach was applied in eight patients requiring sinus floor elevation to place dental implants. After elevation of the sinus membrane, the cavities were filled with 0.6-mm granules of nanocrystalline hydroxyapatite mixed with the patient's blood. A collagen membrane (group 1) or a platelet-rich fibrin (PRF) membrane (group 2) was placed over the bony window. After healing periods between 7 and 11 months (in one case after 24 months), 16 biopsy specimens were harvested with a trephine bur during implant bed preparation. The percentage of new bone, residual filler material, and soft tissue was determined histomorphometrically. Four specimens were excluded from the analysis because of incomplete biopsy removal. In all other specimens, new bone was observed in the augmented region. For group 1, the amount of new bone, residual graft material, and soft tissue was 28.7% ± 5.4%, 25.5% ± 7.6%, and 45.8% ± 3.2%, respectively. For group 2, the values were 28.6% ± 6.90%, 25.7% ± 8.8%, and 45.7% ± 9.3%, respectively. All differences between groups 1 and 2 were not statistically significant. The lowest and highest values of new bone were 21.2% and 34.1% for group 1 and 17.4% and 37.8% for group 2, respectively. The amount of new bone after the use of nanocrystalline hydroxyapatite for sinus floor elevation in humans is comparable to values found in the literature for other synthetic or xenogeneic bone substitute materials. There was no additional beneficial effect of the PRF membrane over the non-cross-linked collagen membrane. (Int J Periodontics Restorative Dent 2014;34:259-267. doi: 10.11607/prd.1419)