Periodontal healing after application of enamel matrix derivative in surgical supra/infrabony periodontal defects in rats with streptozotocin-induced diabetes

BACKGROUND AND OBJECTIVE Epidemiologic and clinical studies have indicated that diabetes is a risk factor for periodontal disease progression and healing. The aim of the present study was to evaluate short-term healing after enamel matrix derivative (EMD) application in combined supra/infrabony periodontal defects in diabetic rats. MATERIAL AND METHODS Thirty male Wistar rats were initially divided into two groups, one with streptozotocin-induced diabetes and another one with healthy (non-diabetic) animals. Bony defects were surgically created on the mesial root of the first maxillary molars. After root surface planing and EDTA conditioning, EMD was applied to the roots at one side of the maxillae, while those on the contralateral sides were left untreated. Animals were killed 3 wk after surgery, and block sections were prepared for histologic and histomorphometric analysis. RESULTS There was statistically significant more gingival recession in diabetic animals than in non-diabetic animals. The length of the junctional epithelium was significantly shorter in the EMD-treated sites in both diabetic and normoglycemic rats. Sulcus depth and length of supracrestal soft connective tissue showed no statistically significant differences between groups. In all animals, new bone formation was observed. Although new bone occurred more frequently in healthy animals, the extent of new bone was not significantly different between groups. In none of the teeth, a layer of new cementum was detectable. EMD had no influence on bone or cementum regeneration. Adverse reactions such as excessive inflammation due to bacterial root colonization, ankylosis and bone fractures were exclusively observed in diabetic animals, irrespective of EMD treatment. CONCLUSION Within the limits of the present study, it can be concluded that periodontal healing was impaired in streptozotocin-induced diabetic rats. EMD had no beneficial effects on new bone and cementum formation during short-term healing in this defect model and could not ameliorate the adverse effects in the systemically compromised animals.

Effect of pulverized natural bone mineral on regeneration of three-wall intrabony defects. A preclinical study.

AIMS The objective of this study is to evaluate the effects of a paste-like bone substitute material with easy handling properties and improved mechanical stability on periodontal regeneration of intrabony defects in dogs. MATERIALS AND METHODS Mandibular and maxillary first and third premolars were extracted, and three-wall intrabony defects were created on second and fourth premolars. After a healing period of 3 months, acute type defects were filled with a paste-like formulation of deproteinized bovine bone mineral (DBBM) (particle size, 0.125-0.25 mm) in a collagenous carrier matrix (T1), pulverized DBBM (particle size, 0.125-0.25 mm) without the carrier (T2), or Bio-Oss® granules (particle size, 0.25-1.00 mm) as control (C). All defects were covered with a Bio-Gide® membrane. The dogs were sacrificed after 12 weeks, and the specimens were analyzed histologically and histometrically. RESULTS Postoperative healing of all defects was uneventful, and no histological signs of inflammation were observed in the augmented and gingival regions. New cementum, new periodontal ligament, and new bone were observed in all three groups. The mean vertical bone gain was 3.26 mm (T1), 3.60 mm (T2), and 3.81 mm (C). That of new cementum was 2.25 mm (T1), 3.88 mm (T2), and 3.53 mm (C). The differences did not reach statistical significance. The DBBM particles were both incorporated in new bone and embedded in immature bone marrow. CONCLUSIONS The results of this preclinical study showed that the 0.125-0.25-mm DBBM particles in a powder or paste formulation resulted in periodontal regeneration comparable to the commercially available DBBM. Osteoconductivity, in particular, was not affected by DBBM size or paste formulation. CLINICAL RELEVANCE The improved handling properties of the paste-like bone substitute consisting of small DBBM particles embedded in a collagen-based carrier hold promise for clinical applications.

Which biomaterials may promote periodontal regeneration in intrabony periodontal defects? A systematic review of preclinical studies.

OBJECTIVE To systematically analyze the regenerative effect of the available biomaterials either alone or in various combinations for the treatment of periodontal intrabony defects as evaluated in preclinical histologic studies. DATA SOURCES A protocol covered all aspects of the systematic review methodology. A literature search was performed in Medline, including hand searching. Combinations of searching terms and several criteria were applied for study identification, selection, and inclusion. The preliminary outcome variable was periodontal regeneration after reconstructive surgery obtained with the various regenerative materials, as demonstrated through histologic/ histomorphometric analysis. New periodontal ligament, new cementum, and new bone formation as a linear measurement in mm or as a percentage of the instrumented root length were recorded. Data were extracted based on the general characteristics, study characteristics, methodologic characteristics, and conclusions. Study selection was limited to preclinical studies involving histologic analysis, evaluating the use of potential regenerative materials (ie, barrier membranes, grafting materials, or growth factors/proteins) for the treatment of periodontal intrabony defects. Any type of biomaterial alone or in various combinations was considered. All studies reporting histologic outcome measures with a healing period of at least 6 weeks were included. A meta-analysis was not possible due to the heterogeneity of the data. CONCLUSION Flap surgery in conjunction with most of the evaluated biomaterials used either alone or in various combinations has been shown to promote periodontal regeneration to a greater extent than control therapy (flap surgery without biomaterials). Among the used biomaterials, autografts revealed the most favorable outcomes, whereas the use of most biologic factors showed inferior results compared to flap surgery.

Effect of enamel matrix derivative on periodontal wound healing and regeneration in an osteoporotic model.

BACKGROUND Despite the worldwide increased prevalence of osteoporosis, no data are available evaluating the effect of an enamel matrix derivative (EMD) on the healing of periodontal defects in patients with osteoporosis. This study aims to evaluate whether the regenerative potential of EMD may be suitable for osteoporosis-related periodontal defects. METHODS Forty female Wistar rats (mean body weight: 200 g) were used for this study. An osteoporosis animal model was carried out by bilateral ovariectomy (OVX) in 20 animals. Ten weeks after OVX, bilateral fenestration defects were created at the buccal aspect of the first mandibular molar. Animals were randomly assigned to four groups of 10 animals per group: 1) control animals with unfilled periodontal defects; 2) control animals with EMD-treated defects; 3) OVX animals with unfilled defects; and 4) OVX animals with EMD-treated defects. The animals were euthanized 28 days later, and the percentage of defect fill and thickness of newly formed bone and cementum were assessed by histomorphometry and microcomputed tomography (micro-CT) analysis. The number of osteoclasts was determined by tartrate-resistant acid phosphatase (TRAP), and angiogenesis was assessed by analyzing formation of blood vessels. RESULTS OVX animals demonstrated significantly reduced bone volume in unfilled defects compared with control defects (18.9% for OVX animals versus 27.2% for control animals) as assessed by micro-CT. The addition of EMD in both OVX and control animals resulted in significantly higher bone density (52.4% and 69.2%, respectively) and bone width (134 versus 165μm) compared with untreated defects; however, the healing in OVX animals treated with EMD was significantly lower than that in control animals treated with EMD. Animals treated with EMD also demonstrated significantly higher cementum formation in both control and OVX animals. The number of TRAP-positive osteoclasts did not vary between untreated and EMD-treated animals; however, a significant increase was observed in all OVX animals. The number of blood vessels and percentage of new vessel formation was significantly higher in EMD-treated samples. CONCLUSIONS The results from the present study suggest that: 1) an osteoporotic phenotype may decrease periodontal regeneration; and 2) EMD may support greater periodontal regeneration in patients suffering from the disease. Additional clinical studies are necessary to fully elucidate the possible beneficial effect of EMD for periodontal regeneration in patients suffering from osteoporosis.

Cell-to-cell communication--periodontal regeneration.

BACKGROUND Although regenerative treatment options are available, periodontal regeneration is still regarded as insufficient and unpredictable. AIM This review article provides scientific background information on the animated 3D film Cell-to-Cell Communication - Periodontal Regeneration. RESULTS Periodontal regeneration is understood as a recapitulation of embryonic mechanisms. Therefore, a thorough understanding of cellular and molecular mechanisms regulating normal tooth root development is imperative to improve existing and develop new periodontal regenerative therapies. However, compared to tooth crown and earlier stages of tooth development, much less is known about the development of the tooth root. The formation of root cementum is considered the critical element in periodontal regeneration. Therefore, much research in recent years has focused on the origin and differentiation of cementoblasts. Evidence is accumulating that the Hertwig's epithelial root sheath (HERS) has a pivotal role in root formation and cementogenesis. Traditionally, ectomesenchymal cells in the dental follicle were thought to differentiate into cementoblasts. According to an alternative theory, however, cementoblasts originate from the HERS. What happens when the periodontal attachment system is traumatically compromised? Minor mechanical insults to the periodontium may spontaneously heal, and the tissues can structurally and functionally be restored. But what happens to the periodontium in case of periodontitis, an infectious disease, after periodontal treatment? A non-regenerative treatment of periodontitis normally results in periodontal repair (i.e., the formation of a long junctional epithelium) rather than regeneration. Thus, a regenerative treatment is indicated to restore the original architecture and function of the periodontium. Guided tissue regeneration or enamel matrix proteins are such regenerative therapies, but further improvement is required. As remnants of HERS persist as epithelial cell rests of Malassez in the periodontal ligament, these epithelial cells are regarded as a stem cell niche that can give rise to new cementoblasts. Enamel matrix proteins and members of the transforming growth factor beta (TGF-ß) superfamily have been implicated in cementoblast differentiation. CONCLUSION A better knowledge of cell-to-cell communication leading to cementoblast differentiation may be used to develop improved regenerative therapies to reconstitute periodontal tissues that were lost due to periodontitis.

Biomaterials for promoting periodontal regeneration in human intrabony defects: a systematic review

Intrabony periodontal defects are a frequent complication of periodontitis and, if left untreated, may negatively affect long-term tooth prognosis. The optimal outcome of treatment in intrabony defects is considered to be the absence of bleeding on probing, the presence of shallow pockets associated with periodontal regeneration (i.e. formation of new root cementum with functionally orientated inserting periodontal ligament fibers connected to new alveolar bone) and no soft-tissue recession. A plethora of different surgical techniques, often including implantation of various types of bone graft and/or bone substitutes, root surface demineralization, guided tissue regeneration, growth and differentiation factors, enamel matrix proteins or various combinations thereof, have been employed to achieve periodontal regeneration. Despite positive observations in animal models and successful outcomes reported for many of the available regenerative techniques and materials in patients, including histologic reports, robust information on the degree to which reported clinical improvements reflect true periodontal regeneration does not exist. Thus, the aim of this review was to summarize, in a systematic manner, the available histologic evidence on the effect of reconstructive periodontal surgery using various types of biomaterials to enhance periodontal wound healing/regeneration in human intrabony defects. In addition, the inherent problems associated with performing human histologic studies and in interpreting the results, as well as certain ethical considerations, are discussed. The results of the present systematic review indicate that periodontal regeneration in human intrabony defects can be achieved to a variable extent using a range of methods and materials. Periodontal regeneration has been observed following the use of a variety of bone grafts and substitutes, guided tissue regeneration, biological factors and combinations thereof. Combination approaches appear to provide the best outcomes, whilst implantation of alloplastic material alone demonstrated limited, to no, periodontal regeneration.

Clinical and Histological Evaluation of a Granular Bovine Bone Biomaterial Used as an Adjunct to Guided Tissue Regeneration With a Bioresorbable Bovine Pericardium Collagen Membrane in the Treatment of Intrabony Periodontal Defects

The aim of the present study is to evaluate the clinical and histologic healing of deep intrabony defects treated with guided tissue regeneration (GTR) with a collagen membrane from bovine pericardium and implantation of granular bovine bone biomaterial.

Clinical Outcomes Following Treatment of Non-contained Intrabony Defects with Enamel Matrix Derivative (EMD) or Guided Tissue Regeneration (GTR). A 12-month Randomized Controlled Clinical trial

The purpose of this study is to compare the healing of deep, non-contained intrabony defects (i.e., with a ?80% 1-wall component and a residual 2- to 3-wall component in the most apical part) treated with either an enamel matrix derivative (EMD) or guided tissue regeneration (GTR) after 12 months.

Clinical and histologic evaluation of granular Beta-tricalcium phosphate for the treatment of human intrabony periodontal defects: a report on five cases

BACKGROUND: The aim of the study is to clinically and histologically evaluate the healing of advanced intrabony defects treated with open flap debridement and the adjunct implantation of granular beta tricalcium phosphate (beta-TCP). METHODS: Five patients, each displaying advanced combined 1- and 2-wall intrabony defects around teeth scheduled for extraction or root resection, were recruited. Approximately 6 months after surgery, the teeth or roots were removed together with a portion of their surrounding soft and hard tissues and processed for histologic evaluation. RESULTS: The mean probing depth (PD) was reduced from 10.8 +/- 2.3 mm presurgically to 4.6 +/- 2.1 mm, whereas a mean clinical attachment level (CAL) gain of 5.0 +/- 0.7 mm was observed. The increase in gingival recession was 1.2 +/- 3.2 mm. The histologic evaluation indicated the formation of new cellular cementum with inserting collagen fibers to a varying extent (mean: 1.9 +/- 0.7 mm; range: 1.2 to 3.03 mm) coronal to the most apical extent of the root instrumentation. The mean new bone formation was 1.0 +/- 0.7 mm (range: 0.0 to 1.9 mm). In most specimens, beta-TCP particles were embedded in the connective tissue, whereas the formation of a mineralized bone-like or cementum-like tissue around the particles was only occasionally observed. CONCLUSION: The present data indicates that treatment of intrabony periodontal defects with this beta-TCP may result in substantial clinical improvements such as PD reduction and CAL gain, but this beta-TCP does not seem to enhance the regeneration of cementum, periodontal ligament, and bone.

Percutaneous collagen induction-regeneration in place of cicatrisation?

Ablative procedures that are used for the improvement of a degenerative process that leads to a loss of skin elasticity and integrity, injure or destroy the epidermis and its basement membrane and lead to fibrosis of the papillary dermis. It was recently shown in clinical and laboratory trials that percutaneous collagen induction (PCI) by multiple needle application is a method for safely treating wrinkles and scars and smoothening the skin without the risk of dyspigmentation. In our study, we describe the effect of PCI on epidermal thickness and the induction of genes relevant for regenerative processes in the skin in a small animal model.

Premature Osteoblast Clustering by Enamel Matrix Proteins Induces Osteoblast Differentiation through Up-Regulation of Connexin 43 and N-Cadherin

In recent years, enamel matrix derivative (EMD) has garnered much interest in the dental field for its apparent bioactivity that stimulates regeneration of periodontal tissues including periodontal ligament, cementum and alveolar bone. Despite its widespread use, the underlying cellular mechanisms remain unclear and an understanding of its biological interactions could identify new strategies for tissue engineering. Previous in vitro research has demonstrated that EMD promotes premature osteoblast clustering at early time points. The aim of the present study was to evaluate the influence of cell clustering on vital osteoblast cell-cell communication and adhesion molecules, connexin 43 (cx43) and N-cadherin (N-cad) as assessed by immunofluorescence imaging, real-time PCR and Western blot analysis. In addition, differentiation markers of osteoblasts were quantified using alkaline phosphatase, osteocalcin and von Kossa staining. EMD significantly increased the expression of connexin 43 and N-cadherin at early time points ranging from 2 to 5 days. Protein expression was localized to cell membranes when compared to control groups. Alkaline phosphatase activity was also significantly increased on EMD-coated samples at 3, 5 and 7 days post seeding. Interestingly, higher activity was localized to cell cluster regions. There was a 3 fold increase in osteocalcin and bone sialoprotein mRNA levels for osteoblasts cultured on EMD-coated culture dishes. Moreover, EMD significantly increased extracellular mineral deposition in cell clusters as assessed through von Kossa staining at 5, 7, 10 and 14 days post seeding. We conclude that EMD up-regulates the expression of vital osteoblast cell-cell communication and adhesion molecules, which enhances the differentiation and mineralization activity of osteoblasts. These findings provide further support for the clinical evidence that EMD increases the speed and quality of new bone formation in vivo.

Morphology and Hemodynamics during Vascular Regeneration in Critically Ischemic Murine Skin Studied by Intravital Microscopy Techniques

With the understanding of angiogenesis and arteriogenesis, new theories about the orchestration of these processes have emerged. The aim of this study was to develop an in vivo model that enables visualization of vascular regenerating mechanisms by intravital microscopy techniques in collateral arteriolar flap vascularity.

A phase IIa randomized controlled clinical and histological pilot study evaluating rhGDF-5/?-TCP for periodontal regeneration

The primary objective of this study was to clinically and histologically evaluate periodontal wound healing/regeneration following surgical implantation of recombinant human growth/differentiation factor-5 (rhGDF-5) adsorbed onto a particulate ?-tricalcium phosphate (?-TCP) carrier rhGDF-5/?-TCP into periodontal defects in man.

Effect of sorafenib on murine liver regeneration

Hepatocellular carcinoma (HCC) is a common cause of cancer-related death. Sorafenib prolongs survival of patients with advanced disease and is approved for the systemic treatment of unresectable HCC. It possesses antiangiogenic and antiproliferative properties by way of inhibition of the receptor tyrosine kinases vascular endothelial growth factor receptor 2 (VEGFR-2) and platelet-derived growth factor receptor-beta 1/2 (PDGFR-β) and the kinase RAF. Sorafenib represents a candidate compound for adjuvant therapy in HCC patients. The aim of our study was to investigate whether sorafenib affects liver regeneration. C57BL6 mice received sorafenib orally at 30 mg/kg/day or its vehicle either for 14 days until the day before hepatectomy or starting the day after surgery or both. Animals were sacrificed 24, 72, and 120 hours after hepatectomy. Liver regeneration was calculated as a percent of initial liver weight. Bromodeoxyuridine (BrdU) incorporation and phospho-extracellular signal-regulated kinase (pERK1/2) were determined by immunohistochemistry on liver sections. VEGF-A, PDGF-BB, and hepatocyte growth factor (HGF) levels were measured in liver tissue homogenates. Histological analysis of scar tissue was performed. Treatment stopped 1 day before surgery had no impact on liver regeneration. Continuous sorafenib treatment and treatment started 1 day after surgery had statistically significant effects on liver regeneration at 120 hours compared to vehicle-treated control animals (72% ± 12 versus control 88% ± 15 and 70% ± 13 versus control 86% ± 5 at 120 hours, both P ≤ 0.02). BrdU incorporation showed decreased numbers of positive nuclei in both groups receiving sorafenib after surgery. Phospho-ERK levels were reduced in sorafenib-treated animals. An increase of VEGF-A levels was observed in mice receiving sorafenib. Wound-healing complications were observed in animals receiving sorafenib after surgery and confirmed on histological sections. CONCLUSION: This preclinical study shows that sorafenib did not impact on liver regeneration when ceased before surgery; however, administration after hepatectomy affected late liver regeneration.