Soft Connective Tissues Research Articles

Review collagen-based biomaterials for wound healing.

With its wide distribution in soft and hard connective tissues, collagen is the most abundant of animal proteins. In vitro, natural collagen can be formed into highly organized, three-dimensional scaffolds that are intrinsically biocompatible, biodegradable, nontoxic upon exogenous application, and endowed with high tensile strength. These attributes make collagen the material of choice for wound healing and tissue engineering applications. In this article, we review the structure and molecular interactions of collagen in vivo; the recent use of natural collagen in sponges, injectables, films and membranes, dressings, and skin grafts; and the on-going development of synthetic collagen mimetic peptides as pylons to anchor cytoactive agents in wound beds.

Comparison of tetrachromic VOF stain to other histochemical staining techniques for characterizing stromal soft and hard tissue components

The components of hard tissues including dentin, enamel, cementum, bone and other calcified deposits, and mature and immature collagen pose problems for identification in routine hematoxylin and eosin (H & E) stained sections. Use of combinations of stains can demonstrate the components of hard tissues and soft tissues distinctly. We assessed the efficacy of the Verde Luz-orange G-acid fuchsin (VOF) stain for differentiating hard and soft connective tissues and compared results with other histochemical staining techniques. Eighty tissue sections comprising developing tooth (30), ossifying fibroma (30) and miscellaneous pathologies (20) expected to contain varying types of calcified tissues were stained with H & E, VOF, and Masson's trichrome (MT). In developing tooth, VOF demonstrated better differentiation of hard tissues, while it was comparable to MT for ossifying fibroma and miscellaneous pathologies. The intensity of staining was greater with VOF than with the other stains studied. VOF stains hard tissue components distinctly and gives good contrast with the surrounding connective tissue. VOF is comparable to MT, but has added advantages including single step staining, rapid and easy procedures, and it distinguishes the maturity of the tissues.

Alk2 Regulates Early Chondrogenic Fate in Fibrodysplasia Ossificans Progressiva Heterotopic Endochondral Ossification

Bone morphogenetic protein (BMP) signaling is a critical regulator of cartilage differentiation and endochondral ossification. Gain-of-function mutations in ALK2, a type I BMP receptor, cause the debilitating disorder fibrodysplasia ossificans progressiva (FOP) and result in progressive heterotopic (extraskeletal) endochondral ossification within soft connective tissues. Here, we used murine mesenchymal progenitor cells to investigate the contribution of Alk2 during chondrogenic differentiation and heterotopic endochondral ossification (HEO). Alk2(R206H/+) (gain-of-function), Alk2(CKO) (loss-of-function), and wild-type mouse embryonic fibroblasts were evaluated for chondrogenic potential. Chondrogenic differentiation was accelerated in Alk2(R206H/+) cells, due in part to enhanced sensitivity to BMP ligand. In vivo, Alk2(R206H/+) cells initiated robust HEO and recruited wild-type cell contribution. Despite expression of other type I BMP receptors (Alk3 and Alk6), chondrogenesis of Alk2(CKO) cells was severely impaired by absence of Alk2 during early differentiation. Alk2 is therefore a direct regulator of cartilage formation and mediates chondrogenic commitment of progenitor cells. These data establish that at least one effect of ALK2 gain-of-function mutations in FOP patients is enhanced chondrogenic differentiation which supports formation of heterotopic endochondral bone. This establishes ALK2 as a plausible therapeutic target during early chondrogenic stages of lesion formation for preventing heterotopic bone formation in FOP and other conditions.

Organ Repair, Hemostasis, and In Vivo Bonding of Medical Devices by Aqueous Solutions of Nanoparticles

AbstractSutures are traumatic to soft connective tissues, such as liver or lungs. Polymer tissue adhesives require complex in vivo control of polymerization or cross‐linking reactions and currently suffer from being toxic, weak, or inefficient within the wet conditions of the body. Herein, we demonstrate using Stöber silica or iron oxide nanoparticles that nanobridging, that is, adhesion by aqueous nanoparticle solutions, can be used in vivo in rats to achieve rapid and strong closure and healing of deep wounds in skin and liver. Nanoparticles were also used to fix polymer membranes to tissues even in the presence of blood flow, such as occurring after liver resection, yielding permanent hemostasis within a minute. Furthermore, medical devices and tissue engineering constructs were fixed to organs such as a beating heart. The simplicity, rapidity, and robustness of nanobridging bode well for clinical applications, surgery, and regenerative medicine.

Organ repair, hemostasis, and in vivo bonding of medical devices by aqueous solutions of nanoparticles.

Sutures are traumatic to soft connective tissues, such as liver or lungs. Polymer tissue adhesives require complex in vivo control of polymerization or cross-linking reactions and currently suffer from being toxic, weak, or inefficient within the wet conditions of the body. Herein, we demonstrate using Stöber silica or iron oxide nanoparticles that nanobridging, that is, adhesion by aqueous nanoparticle solutions, can be used in vivo in rats to achieve rapid and strong closure and healing of deep wounds in skin and liver. Nanoparticles were also used to fix polymer membranes to tissues even in the presence of blood flow, such as occurring after liver resection, yielding permanent hemostasis within a minute. Furthermore, medical devices and tissue engineering constructs were fixed to organs such as a beating heart. The simplicity, rapidity, and robustness of nanobridging bode well for clinical applications, surgery, and regenerative medicine.

Biology of soft tissue wound healing and regeneration – Consensus Report of Group 1 of the 10th European Workshop on Periodontology

The scope of this consensus was to review the biological processes of soft tissue wound healing in the oral cavity and to histologically evaluate soft tissue healing in clinical and pre-clinical models. To review the current knowledge regarding the biological processes of soft tissue wound healing at teeth, implants and on the edentulous ridge. Furthermore, to review soft tissue wound healing at these sites, when using barrier membranes, growth and differentiation factors and soft tissue substitutes. Searches of the literature with respect to recessions at teeth and soft tissue deficiencies at implants, augmentation of the area of keratinized tissue and soft tissue volume were conducted. The available evidence was collected, categorized and summarized. Oral mucosal and skin wound healing follow a similar pattern of the four phases of haemostasis, inflammation, proliferation and maturation/matrix remodelling. The soft connective tissue determines the characteristics of the overlaying oral epithelium. Within 7-14 days, epithelial healing of surgical wounds at teeth is completed. Soft tissue healing following surgery at implants requires 6-8 weeks for maturation. The resulting tissue resembles scar tissue. Well-designed pre-clinical studies providing histological data have been reported describing soft tissue wound healing, when using barrier membranes, growth and differentiation factors and soft tissue substitutes. Few controlled clinical studies with low numbers of patients are available for some of the treatments reviewed at teeth. Whereas, histological new attachment has been demonstrated in pre-clinical studies resulting from some of the treatments reviewed, human histological data commonly report a lack of new attachment but rather long junctional epithelial attachment and connective tissue adhesion. Regarding soft tissue healing at implants human data are very scarce. Oral soft tissue healing at teeth, implants and the edentulous ridge follows the same phases as skin wound healing. Histological studies in humans have not reported new attachment formation at teeth for the indications studied. Human histological data of soft tissue wound healing at implants are limited. The use of barriers membranes, growth and differentiation factors and soft tissue substitutes for the treatment of localized gingival/mucosal recessions, insufficient amount of keratinized tissue and insufficient soft tissue volume is at a developing stage.

Soft tissue wound healing around teeth and dental implants

To provide an overview on the biology and soft tissue wound healing around teeth and dental implants. This narrative review focuses on cell biology and histology of soft tissue wounds around natural teeth and dental implants. The available data indicate that: (a) Oral wounds follow a similar pattern. (b) The tissue specificities of the gingival, alveolar and palatal mucosa appear to be innately and not necessarily functionally determined. (c) The granulation tissue originating from the periodontal ligament or from connective tissue originally covered by keratinized epithelium has the potential to induce keratinization. However, it also appears that deep palatal connective tissue may not have the same potential to induce keratinization as the palatal connective tissue originating from an immediately subepithelial area. (d) Epithelial healing following non-surgical and surgical periodontal therapy appears to be completed after a period of 7–14 days. Structural integrity of a maturing wound between a denuded root surface and a soft tissue flap is achieved at approximately 14-days post-surgery. (e) The formation of the biological width and maturation of the barrier function around transmucosal implants requires 6–8 weeks of healing. (f) The established peri-implant soft connective tissue resembles a scar tissue in composition, fibre orientation, and vasculature. (g) The peri-implant junctional epithelium may reach a greater final length under certain conditions such as implants placed into fresh extraction sockets versus conventional implant procedures in healed sites.

Synthetic Meshes and their Interaction with Biological Tissues in Laser Exposure

The interactions of different kind of synthetic meshes with tissuses and influence of low-intensive laser irradiation – LILI was studied in experiment. Vistar white rats were used. For morphological investigations light and scanning electron microscopy – SEM. SEM revealed the complex structure of synthetic meshes `especially of PTFE mesh. Light-optical studies have shown that the implantation of meshes cause, in the early period of observation, moderate inflammatory reaction. LILI help in reducing of the alterative inflammation phase and leads to concluding with formation of soft connective tissue capsule on the surface of the mesh.

General Anesthesia for Dental Procedures in Patients with Fibrodysplasia Ossificans Progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic condition characterized by progressive heterotopic ossification of skeletal muscle and soft connective tissues, leading to progressive ankylosis of all joints of the axial and appendicular skeleton. Cervical spine fusion, ankylosis of the temporomandibular joints, thoracic insufficiency syndrome, restrictive chest wall disease, and sensitivity to oral trauma complicate airway management and anesthesia and pose life-threatening risks. We conducted a retrospective chart review at 1 institution of patients with FOP who underwent general anesthesia (GA) for dental procedures. Thirty patients underwent 42 general anesthetics. In 35 of 42 cases, GA was induced after the airway was secured by an awake fiberoptic intubation. In 4 of 42 cases, all of them pediatric, GA was first induced with maintenance of spontaneous ventilation, and the trachea was then intubated using a fiberoptic scope. In 2 cases, 1 adult and 1 pediatric, GA was first induced, and the trachea was then intubated using a GlideScope. In 1 case, the patient had a cuffed tracheostomy device in place that was accessed for GA. In 36 of 42 cases, the patients were discharged home on the same day as their dental procedure. No significant postoperative complications were encountered. GA can be administered safely to patients with FOP for dental procedures with attention to perioperative and airway management using a multidisciplinary approach. An awake nasal fiberoptic intubation should be considered the first choice for airway management. Most patients can be discharged home on the same day as their dental procedure.

Fibroblasts from patients affected by Pseudoxanthoma elasticum exhibit an altered PPi metabolism and are more responsive to pro-calcifying stimuli

BackgroundPseudoxanthoma elasticum (PXE) is a genetic disorder characterized by progressive calcification of soft connective tissues. The pathogenesis is still hard to pin down. In PXE dermal fibroblasts, in addition to impaired carboxylation of the vitamin K-dependent inhibitor matrix Gla protein (MGP), we have also demonstrated an up-regulation of alkaline phosphatase activity. In the light of these data we have suggested that both calcium and phosphate metabolism might be locally altered, both pathways acting in synergy on the occurrence of matrix calcification. ObjectiveThis study aims to better explore if cultured PXE fibroblasts, compared to control cells, exhibit a modified inorganic pyrophosphate (PPi) metabolism and are more responsive to pro-calcifying stimuli. MethodsPrimary human dermal fibroblasts isolated from healthy individuals and from PXE patients were cultured for different time points in standard and in pro-calcifying media. The expression of ANKH/ANKH, ENPP1/PC1, ALPL/TNAP, SPP1/OPN was evaluated by qRT-PCR and Western blot, respectively. TNAP activity was measured by spectrophotometric analyses, whereas calcification was investigated by light and electron microscopy as well as by micro-analytical techniques. ResultsIn the presence of pro-calcifying stimuli, dermal fibroblasts alter their phenotype favouring matrix mineralization. In particular, ENPP1/PC1 and SPP1/OPN expression, as well as TNAP activity, was differently expressed in control and in PXE fibroblasts. Moreover, in pathologic cells the ratio between factors favouring and reducing PPi availability exhibits a more pronounced shift towards a pro-calcifying balance. ConclusionPXE fibroblasts are more susceptible to pro-calcifying stimuli and in these cells an altered PPi metabolism contributes to matrix calcification.

Cone-beam computerized tomography as a novel noninvasive method to determine the palatal grafts thickness

Aim: The aim of this study was to apply a novel noninvasive method to obtain high quality images by cone-beam computerized tomography (CBCT) that consistently allowed the determination of the dimensions of palatal masticatory mucosa, which is the main donor area for soft tissue and connective tissue grafts used in periodontics, implant dentistry, and oral surgery. Materials and Methods: A total of 20 patients requiring palatal surgery participated. Thickness of the palatal tissue was measured at various points radiographically. At the time of the CBCT scanning, the patients wore acrylic measurement stent guides with radio-opaque markers at the measurement points. Results: The average thickness of the palatal mucosa was 2.96 mm in the canine area, 3.55 mm at the first premolar, 3.92 mm at the second premolar and 3.20 mm at the first molar. Statistically significant differences were observed as the distance from the gingival margin increased and the tissue over the premolars was found to be thicker than the other teeth. Conclusion: Cone-beam computerized tomography can be used as a noninvasive method accurately and consistently to determine the soft tissue thickness of the palatal masticatory mucosa at different locations on the palate.

Characterization of Mechanotransensitivity of Articular Chondrocytes

Articular cartilage is a protective soft connective tissue lining the ends of bones in weight-bearing joints. It sustains numerous cycles of mechanical loading during normal joint activity. Recent studies showed that mechanical factors not only play a critical role in the pathology of cartilage, e.g. initiation of degenerative joint disease such as osteoarthritis (OA); but also influence the metabolic response of chondrocytes, the only cellular element of cartilage. One of the early events implicated in chondrocyte mechanotransduction is a transient increase of the intracellular Ca2+ ions. Our ultimate goal is to elucidate mechanotransduction mechanisms of chondrocytes both in healthy cartilage and in cartilage damaged by OA. Our objective of this study is to characterize the mechanical loading induced Ca2+ influx of chondrocytes, and to verify the key components contributing to chondrocytes' mechanosensitivity by using selected chemical compounds (Thapsigargin, GSK205, Ruthenium red, FM1-43, Cytochalasin-D, dynasore). Methodologically, we employ ratiometric calcium imaging, Atomic Force Microscope (AFM) and electrophysiology techniques. Our result reveals that chondrocytes are mechanosensitive cells. Typically, we observe individual chondrocytes taking up Ca2+ at ∼600 nM, where basal level of ∼100 nM Ca2+, in response to mechanical loading of ∼300 nN. The Ca2+ influx is mostly from extracellular rather than internal sources. In this meeting, we will introduce our combined measurement platform of AFM and Ca2+ imaging, and present detailed data of the molecular mechanisms governing mechanically-induced transient Ca2+ influx of chondrocytes.

Three dimensional visualization of engineered bone and soft tissue by combined x-ray micro-diffraction and phase contrast tomography

Computed x-ray phase contrast micro-tomography is the most valuable tool for a three dimensional (3D) and non destructive analysis of the tissue engineered bone morphology. We used a Talbot interferometer installed at SYRMEP beamline of the ELETTRA synchrotron (Trieste, Italy) for a precise 3D reconstruction of both bone and soft connective tissue, regenerated in vivo within a porous scaffold. For the first time the x-ray tomographic reconstructions have been combined with x-ray scanning micro-diffraction measurement on the same sample, in order to give an exhaustive identification of the different tissues participating to the biomineralization process. As a result, we were able to investigate in detail the different densities in the tissues, distinguishing the 3D organization of the amorphous calcium phosphate from the collagen matrix. Our experimental approach allows for a deeper understanding of the role of collagen matrix in the organic-mineral transition, which is a crucial issue for the development of new bio-inspired composites.

Practical skills of harmonic scalpel in laparoscopic gastrointestinal surgery

Harmonic scalpel, one of the most commonly used energy tools, have been recognized as an important revolutionary development in surgical device. Due to its convenience in cutting, coagulating, and dissecting harmonic scalpel has been increasingly used to performed surgery by more and more surgeons. In gastrointestinal surgeries, however, many manipulationssuch as dissecting soft connective tissues off the stomach or colon, isolating and cutting particular vessels, would require proper techniques in handling harmonic scalpels. Thus, based on our experiences of using harmonic scalpel in laparoscopic gastrointestinal surgeries, we summarized a "nine-word tactics", which may be helpful for beginners to use harmonic scalpels in a proper and efficient manner.

Information generation and processing systems that regulate periodontal structure and function

The periodontium is a very dynamic organ that responds rapidly to mechanical and chemical stimuli. It is very complex in that it is composed of two hard tissues (cementum and bone) and two soft connective tissues (periodontal ligament and gingiva). Together these tissues are defined by the molecules expressed by the resident periodontal cells in each compartment and this determines not only the structure and function of the periodontium but also how it responds to infection and inflammation. The biological activity of these molecules is tightly regulated in time and space to preserve tissue homeostasis, influence inflammatory responses and participate in tissue regeneration. In this issue of Periodontology 2000 we explore new experimental approaches and data sets which help to understand the molecules and cells that regulate tissue form and structure in health, disease and regeneration.

Matrix mechanics and regulation of the fibroblast phenotype

The oral cavity hosts a variety of different fibroblast populations that are generally responsible for maintaining homeostasis of the soft connective tissue. In addition to regulating the turnover and structural arrangement of collagen and other proteins of the extracellular matrix, fibroblasts perform a number of specialized functions. Certain fibroblast subpopulations in the gingiva, oral mucosa and periodontal ligament serve as progenitor cells with multilineage differentiation and self-renewal characteristics. In the periodontal ligament, fibroblasts further appear to function as mechanosensing entities that regulate collagen-secretory and collagen-remodeling activities according to the level of strain in the ligament. Mechanical challenge also plays an important role during the activation of periodontal fibroblasts in response to injury. Dysregulation of this activation process can lead either to poor healing and chronic wounds or to overly healed wounds with fibrosis. This review will elaborate on the roles of mechanical factors and mechanoperception in fibroblast activation, the molecular features of activated fibroblasts and the regulation mechanisms of fibroblast contraction. Pharmacological interference at each level is currently being pursued to improve the outcome of healing of injured periodontal tissue.

A review on research on development of ligament constitutive relations on macro, meso, and micro levels

Ligaments are densely connective soft tissues capable of maintaining stability and function of knee joint. As an important factor, the constitutive relation of ligament would affect its biomechanics and further play an essential role in the research on ligament injury, healing and treatment. The objective of this paper is to provide an overview of the current research on ligament constitutive relations on the macro, meso, and micro levels as well as the anatomy and histological structure of ligament. Some studies of biomechanical behaviors during ligament injury and healing periods have also been investigated. Based on the research on ligament constitutive relation in the past three decades, a discussion of some research perspectives is also presented, such as a validated accurate measuring method of in situ strain in ligament, a new constitutive relation involving the distribution of ultra-structural properties, and a rational estimation of ligament injury and healing process by the change of its ultra-structural or histological characteristics.

Ectopic calcification in β-thalassemia patients is associated with increased oxidative stress and lower MGP carboxylation

A number of beta-thalassemia (β-thal) patients in the course of the disease exhibit ectopic calcification affecting skin, eyes and the cardiovascular system. Clinical and histopathological features have been described similar to those in pseudoxanthoma elasticum (PXE), although different genes are affected in the two diseases. Cultured dermal fibroblasts from β-thal patients with and without PXE-like clinical manifestations have been compared for parameters of redox balance and for the expression of proteins, which have been already associated with the pathologic mineralisation of soft connective tissues. Even though oxidative stress is a well-known condition of β-thal patients, our results indicate that the occurrence of mineralized elastin is associated with a more pronounced redox disequilibrium, as demonstrated by the intracellular increase of anion superoxide and of oxidized proteins and lipids. Moreover, fibroblasts from β-thal PXE-like patients are characterized by decreased availability of carboxylated matrix Gla protein (MGP), as well as by altered expression of proteins involved in the vitamin K-dependent carboxylation process. Results demonstrate that elastic fibre calcification is promoted when redox balance threshold levels are exceeded and the vitamin K-dependent carboxylation process is affected decreasing the activity of MGP, a well-known inhibitor of ectopic calcification. Furthermore, independently from the primary gene defect, these pathways are similarly involved in fibroblasts from PXE and from β-thal PXE-like patients as well as in other diseases leading to ectopic calcification, thus suggesting that can be used as markers of pathologic mineralisation.

English

Introduction Treatment of soft and hard connective tissues, especially those associated with massive tissue loss, is technically demanding. Both tendon and cartilage have low healing capability. Massive bone injures are often associated with non-union or malunion and other complications. Treatment of a tendon-bone junction is challenging, and treatment of osteoarthritis is more palliative than curative. Tissue engineering, which is composed of three elements including scaffolds, healing promotive factors such as growth factors, and stem cells, is an option. In recent times, stem cellbased therapy has become very popular due to encouraging results that have been reported. This review introduces stem cells and discusses their potential application and roles in tissue regenerative medicine. We have focused on the effectiveness of stem cell-based therapy for different tissue injuries, including tendon, tendon-bone junction, bone, cartilage and osteoarthritis. In vitro clinical evidences have been discussed in detail with the aim to conclude whether stem cell-based therapy is a clinically accepted method. Conclusion This review showed that despite exploring several sources for stem cells, the adult mesenchymal stem cells are still the only reliable stem cells in tissue regenerative medicine. In addition, despite significant improvement in tissue engineering, cell seeding is technically demanding, and direct injection of the stem cells is the only reliable method for cell delivery at the injured site. Because of controversial results and lack of well-designed clinical trials, this review also showed that despite several animal studies and application of stem cells on various tissue injuries, it is still too soon to suggest stem cell therapy as an effective method in restoring morphology and functionality of the injured tissues. Introduction Treatment of injured tendon, ligament, cartilage and bone has often been faced with some difficulties1-3. Such tissues tolerate different types of forces such as stress, torsion and bending during healing, which affects their healing; if not properly managed, ideal healing cannot be expected4-8. In addition, such soft and hard connective tissues have a low healing capability because their circulation is often impaired due to the injury2. Some tissue injuries can be directly repaired through surgery9,10. For example, simple tendon ruptures could be sutured and anastomosed11. Simple fractures could be fixed with a variety of external and internal fixation techniques and devices. However, some tissue injuries are engaged with significant tissue loss and cannot be retrieved by routine surgical methods2. In large, massive tendon injuries, the gap should be reconstructed by autografts or allografts2. In large, massive bone fractures or other types of bone injuries such as osteosarcoma, there is a need to resect the diseased bone, and despite intensive fixation of the bony ends, large gaps are produced. In such conditions, the gap area should be reconstructed by a cancellous bone graft or other types of graft based on the experience and preference of the surgeon12-21. Tissue transplantation has its own limitations, and it is widely accepted that there is a need for alternative solutions2. There are also some other orthopaedic injuries that could not be solved with grafting methods. For example, in anterior cruciate ligament (ACL) reconstruction, although a torn ACL is replaced by an autograft or allograft, major concerns exist in the ligament to bone healing22,23. Most of the failures occur at this site, and this is a major problem24. Healing of cartilage is also extremely slow and if osteoarthritis (OA) happens, the condition becomes more complicated and there is no well-accepted method for retrieving such conditions25-29. Most of the gold standard methods are palliative, and if they are effective, they can only reduce the rate of OA progression30-32. Therefore, there is a need to find a new way with the hope that such injuries will heal with minimal complications and be functional after the healing period. Tissue engineering is one of these new approaches2,33. In the last decade, several advancements have been achieved, and tissue engineering technologies and tissue engineering based products have been developed and produced33. The initial tests have shown encouraging results, however, the results are still primitive and several animal and clinical studies St em C el ls , M ec ha ni cs &

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

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. 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 3wk after surgery, and block sections were prepared for histologic and histomorphometric analysis. 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. 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.