Effects of chitosan nonwoven membrane on periodontal healing of surgically created one-wall intrabony defects in beagle dogs

Morphological Reconstruction of a Critical-Sized Bone Defect in the Maxillofacial Region Using Modified Chitosan in Rats with Sub-Compensated Type I Diabetes Mellitus

It is known that complexes based on natural polysaccharides are able to eliminate bone defects. Prolonged hyperglycemia leads to low bone regeneration and a chronic inflammatory response. The purpose of this study was to increase the efficiency of early bone formation in a cavity of critical size in diabetes mellitus in the experiment. The polyelectrolyte complex contains high-molecular ascorbate of chitosan, chondroitin sulfate, sodium hyaluronate, heparin, adgelon serum growth factor, sodium alginate and amorphous nanohydroxyapatite (CH-SA-HA). Studies were conducted on five groups of white female Wistar rats: group 1-regeneration of a bone defect in healthy animals under a blood clot; group 2-regeneration of a bone defect under a blood clot in animals with diabetes mellitus; group 3-bone regeneration in animals with diabetes mellitus after filling the bone cavity with a collagen sponge; group 4-filling of a bone defect with a CH-SA-HA construct in healthy animals; group 5-filling of a bone defect with a CH-SA-HA construct in animals with diabetes mellitus. Implantation of the CH-SA-HA construct into bone cavities in type I diabetic rats can accelerate the rate of bone tissue repair. The inclusion of modifying polysaccharides and apatite agents in the construction may be a prospect for further improvement of the properties of implants.

Experimental Early Stimulation of Bone Tissue Neo-Formation for Critical Size Elimination Defects in the Maxillofacial Region

A biomaterial is proposed for closing extensive bone defects in the maxillofacial region. The composition of the biomaterial includes high-molecular chitosan, chondroitin sulfate, hyaluronate, heparin, alginate, and inorganic nanostructured hydroxyapatite. The purpose of this study is to demonstrate morphological and histological early signs of reconstruction of a bone cavity of critical size. The studies were carried out on 84 white female rats weighing 200-250 g. The study group consisted of 84 animals in total, 40 in the experimental group and 44 in the control group. In all animals, three-walled bone defects measuring 0.5 × 0.4 × 0.5 cm3 were applied subperiosteally in the region of the angle of the lower jaw and filled in the experimental group using lyophilized gel mass of chitosan-alginate-hydroxyapatite (CH-SA-HA). In control animals, the bone cavities were filled with their own blood clots after bone trepanation and bleeding. The periods for monitoring bone regeneration were 3, 5, and 7 days and 2, 3, 4, 6, 8, and 10 weeks. The control of bone regeneration was carried out using multiple morphological and histological analyses. Results showed that the following process is an obligatory process and is accompanied by the binding and release of angiogenic implantation: the chitosan construct actively replaced early-stage defects with the formation of full-fledged new bone tissue compared to the control group. By the 7th day, morphological analysis showed that the formation of spongy bone tissue could be seen. After 2 weeks, there was a pronounced increase in bone volume (p < 0.01), and at 6 weeks after surgical intervention, the closure of the defect was 70-80%; after 8 weeks, it was 100% without violation of bone morphology with a high degree of mineralization. Thus, the use of modified chitosan after filling eliminates bone defects of critical size in the maxillofacial region, revealing early signs of bone regeneration, and serves as a promising material in reconstructive dentistry.

A Review of Tissue Engineering for Periodontal Tissue Regeneration

Periodontal disease is one of the most common diagnoses in small animal veterinary medicine. This infectious disease of the periodontium is characterized by the inflammation and destruction of the supporting structures of teeth, including periodontal ligament, cementum, and alveolar bone. Traditional periodontal repair techniques make use of open flap debridement, application of graft materials, and membranes to prevent epithelial downgrowth and formation of a long junctional epithelium, which inhibits regeneration and true healing. These techniques have variable efficacy and are made more challenging in veterinary patients due to the cost of treatment for clients, need for anesthesia for surgery and reevaluation, and difficulty in performing necessary diligent home care to maintain oral health. Tissue engineering focuses on methods to regenerate the periodontal apparatus and not simply to repair the tissue, with the possibility of restoring normal physiological functions and health to a previously diseased site. This paper examines tissue engineering applications in periodontal disease by discussing experimental studies that focus on dogs and other animal species where it could potentially be applied in veterinary medicine. The main areas of focus of tissue engineering are discussed, including scaffolds, signaling molecules, stem cells, and gene therapy. To date, although outcomes can still be unpredictable, tissue engineering has been proven to successfully regenerate lost periodontal tissues and this new possibility for treating veterinary patients is discussed.

Simvastatin loaded chitosan guided bone regeneration membranes stimulate bone healing

BACKGROUND AND OBJECTIVE

Electrospun chitosan membranes (ESCM) modified with short-chain fatty acids have the ability to control the release of simvastatin (SMV), an anti-cholesterol drug with osteogenic potential, for guided bone regeneration (GBR) applications. This study evaluated in vivo osteogenic effects of rapid short release of SMV (4 weeks) vs long sustained release (8 weeks) from acetic anhydride (AA)-and hexanoic anhydride (HA)-modified ESCMs, respectively.

METHODS

AA ESCMs loaded with 10 or 50 µg SMV and HA ESCMs loaded with 50 µg SMV were evaluated for biocompatibility and bone formation at 4 and 8 weeks, in 5 mm critical size rat calvarial defects, using histological evaluation and micro-CT analysis.

RESULTS

No severe inflammatory response was noticed around the ESCMs. Less hydrophobic AA membranes showed signs of resorption by week 4 and were almost completely resorbed by week 8 whereas the more hydrophobic HA membranes resorbed slowly, remaining intact over 8 weeks. In micro-CT analysis, 10 µg SMV-loaded AA membranes did not show significant bone formation as compared to non-loaded AA membranes at either evaluation time points. 50 µg SMV-loaded AA membranes stimulated significantly more bone formation than non-loaded AA membranes by week 4 (%bone = 31.0 ± 5.9% (AA50) vs 18.5 ± 13.7% (AA0)) but showed no difference at week 8. HA membranes with 50 µg SMV showed significantly more bone formation as compared to corresponding non-loaded membranes by week 8 (%bone = 61.7 ± 8.9% (HA50) vs 33.9 ± 29.7% (HA0)), though such an effect was not significant at week 4.

CONCLUSION

These results indicate that modified ESCMs may be used to control the release of SMV and promote bone healing in GBR applications.

Engineered scaffolds and cell-based therapy for periodontal regeneration

BACKGROUND

The main objective of regenerative periodontal therapy is to completely restore the periodontal tissues lost. This review summarizes the most recent evidence in support of scaffold- and cell-based tissue engineering, which are expected to play a relevant role in next-generation periodontal regenerative therapy.

METHODS

A literature search (PubMed database) was performed to analyze more recently updated articles regarding periodontal regeneration, scaffolds and cell-based technologies.

RESULTS

Evidence supports the importance of scaffold physical cues to promote periodontal regeneration, including scaffold multicompartmentalization and micropatterning. The in situ delivery of biological mediators and/or cell populations, both stem cells and already differentiated cells, has shown promising in vivo efficacy.

CONCLUSIONS

Porous scaffolds are pivotal for clot stabilization, wound compartmentalization, cell homing and cell nutrients delivery. Given the revolutionary introduction of rapid prototyping technique and cell-based therapies, the fabrication of custom-made scaffolds is not far from being achieved.

Natural graft tissues and synthetic biomaterials for periodontal and alveolar bone reconstructive applications: a review

Periodontal disease is categorized by the destruction of periodontal tissues. Over the years, there have been several clinical techniques and material options that been investigated for periodontal defect repair/regeneration. The development of improved biomaterials for periodontal tissue engineering has significantly improved the available treatment options and their clinical results. Bone replacement graft materials, barrier membranes, various growth factors and combination of these have been used. The available bone tissue replacement materials commonly used include autografts, allografts, xenografts and alloplasts. These graft materials mostly function as osteogenic, osteoinductive and/or osteoconductive scaffolds. Polymers (natural and synthetic) are more widely used as a barrier material in guided tissue regeneration (GTR) and guided bone regeneration (GBR) applications. They work on the principle of epithelial cell exclusion to allow periodontal ligament and alveolar bone cells to repopulate the defect before the normally faster epithelial cells. However, in an attempt to overcome complications related to the epithelial down-growth and/or collapse of the non-rigid barrier membrane and to maintain space, clinicians commonly use a combination of membranes with hard tissue grafts. This article aims to review various available natural tissues and biomaterial based bone replacement graft and membrane options used in periodontal regeneration applications.

Preparation and mechanical properties of poly(p-phenylene sulfide) nanofiber sheets obtained by CO2 laser supersonic multi-drawing

In this study, poly(p-phenylene sulfide) (PPS) nanofiber sheets were fabricated by winding PPS nanofibers onto a spool. Previously, PPS nanofibers have been prepared by irradiating a PPS fiber with a CO2 laser while drawing it at supersonic speeds by single-fiber injection through an orifice. Here, we incorporated the nanofibers obtained into large nanofiber sheets and determined their mechanical properties. Supersonic air was introduced into a vacuum chamber through eight fiber injection orifices to obtain large PPS nanofiber sheets. The nanofibers were collected for 10 min, producing a rectangle sheet with dimensions of 17 cm×18 cm, a thickness of 70 μm, and an average fiber diameter of 700 nm. The dependence of the sheet’s mechanical properties on winding speed was investigated in the machine direction (MD) and traverse direction (TD) at four winding speeds.

Synthesis of piroxicam loaded novel electrospun biodegradable nanocomposite scaffolds for periodontal regeneration

Development of biodegradable composites having the ability to suppress or eliminate the pathogenic micro-biota or modulate the inflammatory response has attracted great interest in order to limit/repair periodontal tissue destruction. The present report includes the development of non-steroidal anti-inflammatory drug encapsulated novel biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) electro-spun (e-spun) composite nanofibrous mats and films and study of the effect of heat treatment on fibers and films morphology. It also describes comparative in-vitro drug release profiles from heat treated and control (non-heat treated) nanofibrous mats and films containing varying concentrations of piroxicam (PX). Electrospinning was used to obtain drug loaded ultrafine fibrous mats. The physical/chemical interactions were evaluated by Fourier Transform Infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). The thermal behavior of the materials was investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Control (not heat treated) and heat treated e-spun fibers mats and films were tested for in vitro drug release studies at physiological pH7.4 and initially, as per requirement burst release patterns were observed from both fibers and films and later sustained release profiles were noted. In vitro cytocompatibility was performed using VERO cell line of epithelial cells and all the synthesized materials were found to be non-cytotoxic. The current observations suggested that these materials are potential candidates for periodontal regeneration.

Periodontal tissue regeneration using enzymatically solidified chitosan hydrogels with or without cell loading

This study is aimed to evaluate the in vivo biocompatibility and periodontal regenerative potential of enzymatically solidified chitosan hydrogels with or without incorporated periodontal ligament cells (PDLCs). To this end, chitosan hydrogels, with (n=8; CHIT+CELL) or without (n=8; CHIT) fluorescently labeled PDLCs, were prepared and transplanted into rat intrabony periodontal defects; untreated defects were used as empty controls (n=8; EMPTY). After 4 weeks, maxillae were harvested, decalcified, and used for histological, histomorphometrical, and immunohistochemical assessments. The results showed that PDLCs remained viable upon encapsulation within chitosan hydrogels before transplantation. Histological analysis demonstrated that the chitosan hydrogels were largely degraded after 4 weeks of implantation, without any adverse reaction in the surrounding tissue. In terms of periodontal regeneration, alveolar bone height, alveolar bone area, and epithelial downgrowth were comparable for CHIT, CHIT+CELL, as well as EMPTY groups. In contrast, both CHIT and CHIT+CELL showed a significant increase in functional ligament length compared with EMPTY. From a cellular perspective, the contribution of chitosan hydrogel-incorporated cells to the periodontal regeneration could not be ascertained, as no signal from transplanted PDLCs could be detected at 4 weeks posttransplantation. The results demonstrated that enzymatically solidified chitosan hydrogels are highly biocompatible and biodegradable. Moreover, chitosan hydrogels without cell loading can improve periodontal regeneration in terms of functional ligament length, indicating the great potential of this hydrogel in clinical applications. Further work on the use of chitosan hydrogels as cell carriers is required.

Antibacterial Activity of a Chitosan-PVA-Ag+-Tobermorite Composite for Periodontal Repair

A polymer-mineral composite was prepared by solvent casting a mixture of chitosan, poly(vinyl alcohol), and Ag+-exchanged tobermorite in dilute acetic acid and characterised by scanning electron microscopy and Fourier transform infrared spectroscopy. The in vitro bioactivity of the CPTAg membrane was confirmed by the formation of hydroxyapatite on its surface in simulated body fluid. The alkaline dissolution products of the tobermorite lattice buffered the acidic breakdown products of the chitosan polymer and the presence of silver ions resulted in marked antimicrobial action against S. aureus, P. aeruginosa, and E. coli. The in vitro cytocompatibility of the CPTAg membrane was confirmed using MG63 osteosarcoma cells. The findings of this preliminary study have indicated that chitosan-poly(vinyl alcohol)-Ag+-tobermorite composites may be suitable materials for guided tissue regeneration applications.

Biomaterials for periodontal regeneration: a review of ceramics and polymers

Periodontal disease is characterized by the destruction of periodontal tissues. Various methods of regenerative periodontal therapy, including the use of barrier membranes, bone replacement grafts, growth factors and the combination of these procedures have been investigated. The development of biomaterials for tissue engineering has considerably improved the available treatment options above. They fall into two broad classes: ceramics and polymers. The available ceramic-based materials include calcium phosphate (eg, tricalcium phosphate and hydroxyapatite), calcium sulfate and bioactive glass. The bioactive glass bonds to the bone with the formation of a layer of carbonated hydroxyapatite in situ. The natural polymers include modified polysaccharides (eg, chitosan,) and polypeptides (collagen and gelatin). Synthetic polymers [eg, poly(glycolic acid), poly(L-lactic acid)] provide a platform for exhibiting the biomechanical properties of scaffolds in tissue engineering. The materials usually work as osteogenic, osteoconductive and osteoinductive scaffolds. Polymers are more widely used as a barrier material in guided tissue regeneration (GTR). They are shown to exclude epithelial downgrowth and allow periodontal ligament and alveolar bone cells to repopulate the defect. An attempt to overcome the problems related to a collapse of the barrier membrane in GTR or epithelial downgrowth is the use of a combination of barrier membranes and grafting materials. This article reviews various biomaterials including scaffolds and membranes used for periodontal treatment and their impacts on the experimental or clinical management of periodontal defect.

Fabrication of a chitosan/bioglass three-dimensional porous scaffold for bone tissue engineering applications

A chitosan/bioglass three-dimensional porous scaffold with excellent biocompatibility and mechanical properties has been developed for the treatment of bone defects.

Evaluation of biocompatibility and degradation of chitosan nanofiber membrane crosslinked with genipin

Chitosan, a natural polysaccharide, has demonstrated potential as a degradable biocompatible guided bone regeneration membrane. This study aimed to evaluate the in vivo biocompatibility and degradation of chitosan nanofiber membranes, with and without genipin crosslinking as compared with a commercial collagen membrane in rat model. Chitosan nanofiber membranes, with and without genipin crosslinking, and collagen membrane (control) were implanted subcutaneously in the backs of 30 rats. The membranes were analyzed histologically at 2, 4, 8, 12, 16, and 20 weeks. Sections were viewed and graded by a blinded pathologist using a 4-point scoring system (0 = absent, 1 = mild, 2 = moderate, and 3 = severe) to determine the tissue reaction to the membranes and to observe membrane degradation. There was no statistically significant difference in histological scores among chitosan and collagen membranes at different time points. Absence or minimal inflammation was observed in 57-74% of the membranes across all groups. Most chitosan membranes persisted for 16-20 weeks, whereas most collagen membranes disappeared by resorption at 12-16 weeks. The general tissue response to chitosan nanofiber membranes with and without genipin crosslinking, was similar to that of control commercial collagen membrane. However, the chitosan membranes exhibited slower degradation rates than collagen membranes.

Comparison of treatment effects of guided tissue regeneration on infrabony lesions between animal and human studies: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

For ethical reasons it is becoming increasingly more difficult to obtain, from clinical studies, histological data on infrabony defects treated with guided tissue regeneration (GTR) techniques. The aim of this systematic review was to find the value of extrapolating animal data on treatment of periodontal infrabony lesions, using GTR only or GTR + bone grafts, to human clinical results.

MATERIAL AND METHODS

Searches of the PubMed and Cochrane databases were combined with hand searching of articles published from 1 January 1969 to 1 August 2012. The search included any type of barrier membrane, with or without grafted materials, used to treat periodontal infrabony lesions. All studies with histological or re-entry methodology outcome parameters that evaluated bone-filling and/or new-cementum-formation ratios from a defect depth were collected. When comparing animal and human outcomes, a meta-analysis was used to evaluate the bone-filling ratio, but only a descriptive analysis of the histological studies was performed.

RESULTS

In total, 22 studies were selected for the meta-analysis. In the GTR + bone graft groups the weighted-average bone-filling ratios were 52% (95% CI: 18-85%) in animals and 57% (95% CI: 30-83%) in humans, which were not statistically significantly different (p = 0.825). Similar results were found in the GTR-only groups, in which the weighted-average bone-filling ratios were 54% (95% CI: 37-72%) in animals and 59% (95% CI: 42-77%) in humans (p = 0.703). New-cementum formation of GTR only and GTR + bone grafts showed comparable ratio outcomes, and both were superior to the control group in animals only (p = 0.042).

CONCLUSION

Although quality assessments differed between animal and human studies, our analysis indicated that animal models and human results showed similar bone-filling ratios in infrabony defects treated with GTR only or with GTR + bone grafting.

Advanced reconstructive technologies for periodontal tissue repair

Reconstructive therapies to promote the regeneration of lost periodontal support have been investigated through both preclinical and clinical studies. Advanced regenerative technologies using new barrier-membrane techniques, cell-growth-stimulating proteins or gene-delivery applications have entered the clinical arena. Wound-healing approaches using growth factors to target the restoration of tooth-supporting bone, periodontal ligament and cementum are shown to significantly advance the field of periodontal-regenerative medicine. Topical delivery of growth factors, such as platelet-derived growth factor, fibroblast growth factor or bone morphogenetic proteins, to periodontal wounds has demonstrated promising results. Future directions in the delivery of growth factors or other signaling models involve the development of innovative scaffolding matrices, cell therapy and gene transfer, and these issues are discussed in this paper.

Chitosan as a barrier membrane material in periodontal tissue regeneration

Periodontal regeneration is defined as regeneration of the tooth-supporting tissues including cementum, periodontal ligament, and alveolar bone. Guided tissue regeneration (GTR) has been demonstrated to be an effective technique to achieve periodontal regeneration. In the GTR procedures, various kinds of membranes play important roles. Chitosan, a deacetylated derivative of chitin, is biocompatible, biodegradable, and antimicrobial. It acts as hydrating agent and possesses tissue healing and osteoinducing effect. Chitosan can be easily processed into membranes, gels, nanofibers, beads, nanoparticles, scaffolds, and sponges forms and can be used in drug delivery systems. Here, we review the bioproperties of chitosan and report the progress of application of chitosan as membranes in GTR and guided bone regeneration (GBR), which indicates that chitosan could be a good substrate candidate as the materials for the GTR/GBR membranes.

Scaffolds based bone tissue engineering: the role of chitosan

As life expectancy increases, malfunction or loss of tissue caused by injury or disease leads to reduced quality of life in many patients at significant socioeconomic cost. Even though major progress has been made in the field of bone tissue engineering, present therapies, such as bone grafts, still have limitations. Current research on biodegradable polymers is emerging, combining these structures with osteogenic cells, as an alternative to autologous bone grafts. Different types of biodegradable materials have been proposed for the preparation of three-dimensional porous scaffolds for bone tissue engineering. Among them, natural polymers are one of the most attractive options, mainly due to their similarities with extracellular matrix, chemical versatility, good biological performance, and inherent cellular interactions. In this review, special attention is given to chitosan as a biomaterial for bone tissue engineering applications. An extensive literature survey was performed on the preparation of chitosan scaffolds and their in vitro biological performance as well as their potential to facilitate in vivo bone regeneration. The present review also aims to offer the reader a general overview of all components needed to engineer new bone tissue. It gives a brief background on bone biology, followed by an explanation of all components in bone tissue engineering, as well as describing different tissue engineering strategies. Moreover, also discussed are the typical models used to evaluate in vitro functionality of a tissue-engineered construct and in vivo models to assess the potential to regenerate bone tissue are discussed.

Interproximal periodontal defect model in dogs: a pilot study

OBJECTIVE

This study aimed to evaluate the validity of a surgically created interproximal periodontal defect in dogs.

MATERIALS AND METHODS

Surgery was performed in the interproximal area between the maxillary second and third premolars in two beagle dogs. Following an incision and reflection of the gingival flap, a 3-mm wide and 5-mm high defect was prepared surgically at the interproximal area. A thorough root planing was performed and the flap was coronally positioned and sutured. The contra-lateral area was served as the control with no surgical intervention. After 8 weeks of healing, the animals were killed and the defect was analysed histometrically and radiographically.

RESULTS

The interproximal periodontal defect resembled a naturally occurring defect and mimicked a clinical situation. After healing, the defect showed limited bone (0.89±0.02mm) and cementum regeneration (1.50± 0.48mm).

CONCLUSIONS

Within the limitations of this pilot study, the interproximal periodontal defect showed limited bone and cementum regeneration. Thus, it can be considered as a standardized, reproducible defect model for testing new biomaterials.

Biological effects of a porcine-derived collagen membrane on intrabony defects

Purpose

To prolong the degradation time of collagen membranes, various cross-linking techniques have been developed. For cross-linking, chemicals such as formaldehyde and glutaraldehyde are added to collagen membranes, but these chemicals could adversely affect surrounding tissues. The aim of this study is to evaluate the ability of porous non-chemical cross-linking porcine-derived collagen nanofibrous membrane to enhance bone and associated tissue regeneration in one-wall intrabony defects in beagle dogs.

Methods

The second and third mandibular premolars and the first molars of 2 adult beagles were extracted bilaterally and the extraction sites were allowed to heal for 10 weeks. One-wall intrabony defects were prepared bilaterally on the mesial and distal side of the fourth mandibular premolars. Among eight defects, four defects were not covered with membrane as controls and the other four defects were covered with membrane as the experimental group. The animals were sacrificed 10 weeks after surgery.

Results

Wound healing was generally uneventful. For all parameters evaluating bone regeneration, the experimental group showed significantly superior results compared to the control. In new bone height (NBh), the experimental group exhibited a greater mean value than the control (3.04 ± 0.23 mm/1.57 ± 0.59, P = 0.003). Also, in new bone area (NBa) and new bone volume (NBv), the experimental group showed superior results compared to the control (NBa, 34.48 ± 10.21% vs. 5.09 ± 5.76%, P = 0.014; and NBv, 28.04 ± 12.96 vs. 1.55 ± 0.57, P = 0.041). On the other hand, for parameters evaluating periodontal tissue regeneration, including junctional epithelium migration and new cementum height, there were no statistically significant differences between two groups.

Conclusions

Within the limitations of this study, this collagen membrane enhanced bone regeneration at one-wall intrabony defects. On the other hand, no influence of this membrane on periodontal tissue regeneration could be ascertained in this study.

Periodontal wound healing/regeneration following implantation of recombinant human growth/differentiation factor-5 in a beta-tricalcium phosphate carrier into one-wall intrabony defects in dogs

OBJECTIVE

Recombinant human growth/differentiation factor-5 (rhGDF-5) is being evaluated as a candidate therapy in support of periodontal regeneration. The objective of this study was to evaluate periodontal wound healing/regeneration following the application of rhGDF-5 on a particulate beta-tricalcium phosphate (beta-TCP) carrier using an established defect model.

MATERIALS AND METHODS

Bilateral 4 x 5 mm (width x depth), one-wall, critical-size, intrabony periodontal defects were surgically created at the mandibular second and fourth pre-molar teeth in 15 Beagle dogs. Unilateral defects in five animals received rhGDF-5/beta-TCP (Scil Technology GmbH); five animals received beta-TCP solo; and five animals served as sham-surgery controls. Contralateral sites received treatments reported elsewhere. The animals were sacrificed following an 8-week healing interval for histological examination.

RESULTS

Clinical healing was generally uneventful. Sites implanted with rhGDF-5/beta-TCP exhibited greater enhanced cementum and bone formation compared with beta-TCP and sham-surgery controls; cementum regeneration averaged (+/- SD) 3.83 +/- 0.73 versus 1.65 +/- 0.82 and 2.48 +/- 1.28 mm for the controls (p<0.05). Corresponding values for bone regeneration height averaged 3.26 +/- 0.30 versus 1.70 +/- 0.66 and 1.68 +/- 0.49 mm (p<0.05), and bone area 10.45 +/- 2.26 versus 6.31 +/- 2.41 and 3.00 +/- 1.97 mm(2) (p<0.05). Cementum regeneration included cellular/acellular cementum with or without a functionally oriented periodontal ligament. A non-specific connective tissue attachment was evident in the sham-surgery control. Controls exhibited mostly woven bone with primary osteons, whereas rhGDF-5/beta-TCP sites showed a noticeable extent of lamellar bone. Sites receiving rhGDF-5/beta-TCP or beta-TCP showed some residual beta-TCP granules apparently undergoing biodegradation without obvious differences between the sites. Sites receiving beta-TCP alone commonly showed residual beta-TCP granules sequestered in the connective tissue or fibrovascular marrow.

CONCLUSION

rhGDF-5/beta-TCP has a greater potential to support the regeneration of the periodontal attachment. Long-term studies are necessary to confirm the uneventful maturation of the regenerated tissues.

Effects of chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 on bone formation in femoral condyle-contained bone defects

Calcium sulfate has a rapid degradation rate and little osteoinductive capability. Chitosan-coated pressed calcium sulfate pellets combined with recombinant human bone morphogenetic protein 2 (rhBMP-2) have been developed that exhibit decreased resorption speed and increased compressive strength and osteoinduction. A rabbit femoral condyle-contained bone defect model was used to study the restoration of the defects treated with chitosan-coated pressed calcium sulfate pellets combined with rhBMP-2, chitosan-coated pressed calcium sulfate pellets, and uncoated pressed calcium sulfate pellets. No pellets were implanted in the control group. After 3 and 13 weeks, the results indicated that chitosan-coated pressed calcium sulfate pellets exhibited relatively slower resorption that closely coincides with the growth rate of new bone and enhanced osteogenesis when combined with rhBMP-2.

Periodontal regeneration in experimentally-induced alveolar bone dehiscence by an improved porous biphasic calcium phosphate ceramic in beagle dogs

Regeneration of lost periodontium is the focus of periodontal therapy. To achieve the effective regeneration, a number of bone graft substitute materials have been developed. This study aimed to investigate the histological response in alveolar bone dehiscences which were filled with an improved biphasic calcium phosphate (BCP) ceramic with more reasonable pore diameter, pore wall thickness and porosity. Twenty-four alveolar bone dehiscences were made surgically in twelve beagle dogs by reflecting mucoperiosteal flaps on the buccal aspect of bilateral lower second premolars and removing alveolar bone. The left dehiscences were treated with BCP ceramic and the contralaterals were cured with the open flap debridement (OFD) as controls. Three dogs were used at week 4, 12, and 24 respectively. Histological observations were processed through three-dimensional micro-computed tomographic imaging, fluorescence and light microscopy. The histological study indicated that the biphasic ceramic was biocompatible, and regeneration was achieved more effectively through the BCP treatment. There were also arrest of epithelial migration apically and formation of new bone and cementum, as well as proliferation of fibrous connective tissues that became attached to the newly formed cementum at week 24, while there was no significant periodontal regeneration in the OFD group only with epithelial tissue migrating into the dehiscence regions. Clinically speaking, though the surgical location formed a limitation to the application of the improved BCP on the periodontal regeneration, the actual result was positive. It proved that the BCP had biocompatibility and was able to act as a stable scaffold to induce periodontal regeneration effectively.

Antibacterial activity of chitosan-based matrices on oral pathogens

Chitosan is a well sought-after polysaccharide in biomedical applications due to its biocompatibility, biodegradability to non-toxic substances, and ease of fabrication into various configurations. However, alterations in the anti-bacterial properties of chitosan in various forms is not completely understood. The objective of this study was to evaluate the anti-bacterial properties of chitosan matrices in different configurations against two pathogens-Gram-positive Streptococcus mutans and Gram-negative Actinobacillus actinomycetemcomitans. Two-dimensional (2-D) membranes and three-dimensional (3-D) porous scaffolds were synthesized by air drying and controlled-rate freeze drying. Matrices were suspended in bacterial broths with or without lysozyme (enzyme that degrades chitosan). Influences of pore size, blending with Polycaprolactone (PCL, a synthetic polymer), and neutralization process on bacterial proliferation were studied. Transient changes in optical density of the broth, adhesion characteristics, viability, and contact-dependent bacterial activity were assessed. 3-D porous scaffolds were more effective in reducing the proliferation of S. mutans in suspension than 2-D membranes. However, no significant differences were observed on the proliferation of A. actinomycetemcomitans. Presence of lysozyme significantly increased the antibacterial activity of chitosan against A. actinomycetemcomitans. Pore size did not affect the proliferation kinetics of either species, with or without lysozyme. NaOH neutralization of chitosan increased bacterial adhesion whereas ethanol neutralization inhibited adhesion without lowering proliferation. Mat culture tests indicated that chitosan does not allow proliferation on its surface and it loses antibacterial activity upon blending with PCL. Results suggest that the chemical and structural characteristics of chitosan-based matrices can be manipulated to influence the interaction of different bacterial species.

Histological analysis of the effect of accelerated portland cement as a bone graft substitute on experimentally-created three-walled intrabony defects in dogs

BACKGROUND AND AIMS

Recent literature shows that accelerated Portland cement (APC) is a non-toxic material that may have potential to promote bone healing. The objective of this study was to histologically evaluate periodontal healing focusing on new bone regeneration following implantation of APC into intra-bony defects in dogs.

MATERIALS AND METHODS

Three-wall intra-bony periodontal defects were surgically created at the mesial aspect of the first molar in both sides of mandible in six dogs. One side was randomly filled with the material and other received a flap operation only. The animals were euthanized eight weeks post-surgery when block sections of the defect sites were collected and prepared for qualitative histological analysis.

RESULTS

Compared to control group, stimulation of growth of new bone tissue in the cavity con-taining APC was significantly prominent in three of six cases, showing osteoid formation with osteoblastic rimming and new bone trabeculla. New bone formation was observed just close to cavity containing APC. Connective tissue proliferation and downgrowth of epithelium were signif-icantly less than those of control group.

CONCLUSION

Our results are encouraging for the use of APC as a bone substitute, but more comprehensive study are necessary before warranting clinical use.

The integration of chitosan-coated titanium in bone: an in vivo study in rabbits

PROCEDURE

Much research is directed at surface modifications to enhance osseointegration of implants. A new potential coating is the biopolymer, chitosan, the deacetylated derivative of the natural polysaccharide, chitin. Chitosan is biocompatible, degradable, nontoxic, and exhibits osteogenic properties. The aim of this research was to investigate the hypothesis that chitosan-coated titanium supports bone formation and osseointegration.

MATERIALS AND METHODS

Chitosan (1 wt% of 92.3% deacetylated chitosan in 1% acetic acid) was solution cast and bonded to rough ground titanium pins (2-mm diameterx4-mm long) via silane reactions. Calcium phosphate sputter-coated titanium and uncoated titanium pins were used as controls. Two chitosan-coated pins, and 1 each of calcium phosphate coated and uncoated pins were implanted unilaterally in the tibia of 16 adult male New Zealand white rabbits. At 2, 4, 8, and 12 weeks, undecalcified sections were histologically evaluated for healing and bone formation.

RESULTS

Histological evaluations of tissues in contact with the chitosan-coated pins indicated minimal inflammatory response and a typical healing sequence of fibrous, woven bone formation, followed by development of lamellar bone. These observations were similar to those for tissues interfacing the control calcium phosphate-coated and uncoated titanium implants. Quantitative comparisons of the bone-implant interface were not possible since 31% of the implants migrated into the tibial marrow space after implantation due to insufficient cortical bone thickness to hold pins in place during healing.

CONCLUSION

These data support the hypothesis that chitosan-coatings are able to develop a close bony apposition or the osseointegration of dental/craniofacial and orthopedic implants.

Favorable Periodontal Healing of 1-Wall Infrabony Defects After Application of Calcium Phosphate Cement Wall Alone or in Combination With Enamel Matrix Derivative: A Pilot Study With Canine Mandibles

BACKGROUND

Although various periodontal regenerative therapies are used, their effects on non-contained infrabony defects are unpredictable. Our previous studies showed that injectable, moldable, fast-setting calcium phosphate cement (CPC) promoted histocompatible periodontal healing in 3-wall intrabony defects. The present study evaluated healing patterns after surgical application of CPC walls with and without an enamel matrix derivative (EMD) in 1-wall infrabony defects in dogs.

METHODS

One-wall infrabony defects (5 x 5 x 4 mm) were created surgically on the mesial and distal sides of bilateral mandibular fourth premolars in four beagle dogs. After elevating a full-thickness flap, exposed root surfaces were planed thoroughly. The 16 defects were assigned randomly to one of the following experimental conditions: CPC, CPC+EMD, EMD, and open flap debridement (OFD). Ten weeks post-surgery, the animals were sacrificed, and histologic specimens were prepared for histomorphometric evaluation.

RESULTS

Defect sites treated with EMD only exhibited varying degrees of new cementum and new bone formation, whereas the OFD group presented only limited new cementum and bone formation. Defect sites where a CPC wall was implanted (CPC and CPC+EMD groups) revealed significantly greater regeneration of new bone and new cementum than in the EMD and OFD groups. No significant differences were observed between the CPC and CPC+EMD groups.

CONCLUSIONS

CPC walls with and without EMD promoted regeneration of alveolar bone and cementum in 1-wall infrabony defects. Space and stable wound healing are believed to be crucial for periodontal regeneration in non-contained infrabony defects.