Bacterial adhesion to antibiotic-loaded guided tissue regeneration membranes - a scanning electron microscopy study

A Novel Device for the Evaluation of In Vitro Bacterial Colonization in Membranes for Guided Tissue and Bone Regeneration

Purpose: To evaluate, in vitro, the efficiency of a novel apparatus to test the adherence and penetration of bacteria on different membranes for guided regeneration. Methodology: To create the 3D device, Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) systems were used. Three types of biomaterials were tested (n = 6): (DT) a collagen membrane; (DS) a polymer membrane; and (LP) a dense polytetrafluoroethylene barrier. The biomaterials were adapted to the apparatuses and challenged with two different monospecies bacterial culture of A. actinomycetemcomitans b and S. mutans. After 2 h, bacterial adherence and penetration were quantified by counting the number of colony-forming units (CFUs). Two specimens from each group were used for image analysis using Confocal Laser Scanning Microscopy. Statistical analysis was performed. Findings: The DS group had a higher adherence of S. mutans compared to A. actinomycetemcomitans b (p = 0.05). There was less adherence of A. actinomycetemcomitans b in the DS group, compared to the LP (p = 0.011) and DT (p < 0.001) groups. Only the membranes allowed penetration, which was blocked by barriers. The DT group allowed a greater penetration of S. mutans to occur compared to A. actinomycetemcomitans b (p = 0.009), which showed a higher penetration into the DS membranes compared to S. mutans (p = 0.016). The penetration of A. actinomycetemcomitans b through DS was higher compared to its penetration through DT and LP (p < 0.01 for both). DT and DS allowed a greater penetration of S. mutans to occur compared to LP, which prevented both bacterial species from penetrating. Conclusion: The apparatus allowed for the settlement and complete sealing of the biomaterials, enabling standardization.

Management of postoperative outcomes of polytetrafluoroethylene membranes in alveolar ridge reconstruction: a systematic review

Guided bone regeneration (GBR) is a validated technique with satisfactory outcomes during 30 years of follow-up. The use of polytetrafluoroethylene (PTFE) membrane for vertical augmentation has been studied extensively. However, studies have reported exposure rates of up to 31%, there is no consensus on the management of postoperative exposure. The objective of this study was to propose a management approach for postoperative exposure of polytetrafluoroethylene (PTFE) membranes in alveolar ridge reconstruction.

MATERIAL AND METHOD

An electronic search in PubMed Central's and additional electronic databases was performed. The search strategy was limited to human studies, full-text English or French articles published from 1990 until april 2023. The extracted data included defect location, membrane type, biomaterials, time to postoperative exposure, and Fontana classification stage. Protocol bias assessment was performed using an adaptation of the QUADAS-2 tool. This review has been registered on PROSPERO (ID: CRD42023445497).

RESULTS

A total of 43 articles were found to be eligible, and 11 of these met the predefined inclusion and exclusion criteria. Based on the results of this systematic review, an algorithm for the management of PTFE membrane exposure is proposed.

CONCLUSION

Postoperative membrane exposure is not a determining factor for the success of bone grafting. In cases with postoperative complications, the majority of cases still achieved adequate implant-prosthetic rehabilitation. Lastly, this series of 11 articles was insufficient to draw conclusions regarding good practice recommendations. A larger series is required to validate the specific management approaches.

Periodontal Guided Tissue Regeneration Membranes: Limitations and Possible Solutions for the Bottleneck Analysis

Guided tissue regeneration (GTR) is an important surgical method for periodontal regeneration. By placing barrier membrane on the root surface of the tooth to guide the adhesion and proliferation of periodontal ligament cells, periodontal tissue regeneration can be achieved. This review intends to analyze the current limitations of GTR membranes and to propose possible solutions for developing new ones. Limitations of current GTR membranes include nonabsorbable membranes and absorbable synthetic polymer membranes exhibit weak biocompatibility; when applying to a large defect wound, the natural collagen membrane with fast degradation rate have limited mechanical strength, and the barrier function may not be maintained well. Although the degradation time can be prolonged after cross-linking, it may cause foreign body reaction and affect tissue integration; The clinical operation of current barrier membranes is inconvenient. In addition, most of the barrier membranes lack bioactivity and will not actively promote periodontal tissue regeneration. Possible solutions include using electrospinning (ELS) techniques, nanofiber scaffolds, or developing functional gradient membranes to improve their biocompatibility; adding Mg, Zn, and/or other metal alloys, or using 3D printing technology to improve their mechanical strength; increasing the concentration of nanoparticles or using directional arrangement of membrane fibers to control the fiber diameter and porosity of the membrane, which can improve their barrier function; mixing natural and synthetic polymers as well as other biomaterials with different degradation rates in proportion to change the degradation rate and maintain barrier function; to improve the convenience of clinical operation, barrier membranes that meets personalized adhesion to the wound defect can be manufactured; developing local controlled release drug delivery systems to improve their bioactivity. Impact statement This review provides an up-to-date summary of commonly commercial periodontal guided tissue regeneration membranes, and analyze their limitations in clinical use. Using studies published recently to explore possible solutions from several perspectives and to raise possible strategies in the future. Several strategies have tested in vivo/in vitro, which will guide the way to propel clinical translation, meeting clinical needs.

In vitro evaluation of membranes for regenerative procedures against oral bacteria

The current literature on guided bone regeneration (GBR) and guided tissue regeneration (GTR) membrane contamination reports that the physicochemical characteristics of these biomaterials might influence affinity to bacteria, which appears to be a major drawback for the clinical outcome of the regenerative procedures. Thus, this study aimed to evaluate, in vitro, a multispecies biofilm adherence and passage of bacteria through different types of commercially available membranes for GTR/GBR. Four types of membranes were tested (n=12): LC) Lumina Coat®; JS) Jason®; BG) Biogide®; and LP) Lumina PTFE®. Aluminum foil (AL) simulated an impermeable barrier and was used as the control. The membranes were adapted to specific apparatus and challenged with a mixed bacterial culture composed of A. actinomycetemcomitans b, S. mutans, S. mitis, and A. israelii. After 2 h or 7 days, bacterial adhesion and passage of bacteria were evaluated through CFU counting, which was analyzed by two-way ANOVA e post hoc Tukey, at a 5% significance level. Representative areas of two membranes of each group were analyzed through scanning electron microscopy (SEM) to assess the morphology and organization of the biofilm over the membrane fibers. LC and LP presented similar values of adhered bacterial cells (p > 0.05), significantly inferior when compared to the other groups, in both time points (p < 0.05). All the tested groups were permeable to bacterial cells, with no significant difference between the trial period of 2 h and 7 days (p > 0.05). SEM analyses demonstrated that adhered bacteria number increased throughout the time points (2 h < 7 days). Commercially available biological membranes demonstrated intense bacterial adherence and passage of bacteria, which increased throughout the trial period.

Underestimated microbial infection of resorbable membranes on guided regeneration

Barrier membranes are critical in creating tissuecompartmentalization for guided tissue (GTR) and bone regeneration (GBR) therapies. More recently, resorbable membranes have been widely used for tissue and bone regeneration due to their improved properties and the dispensable re-entry surgery for membrane removal. However, in cases with membrane exposure, this may lead to microbial contamination that will compromise the integrity of the membrane, surrounding tissue, and bone regeneration, resulting in treatment failure. Although the microbial infection can negatively influence the clinical outcomes of regenerative therapy, such as GBR and GTR, there is a lack of clinical investigations in this field, especially concerning the microbial colonization of different types of membranes. Importantly, a deeper understanding of the mechanisms of biofilm growth and composition and pathogenesis on exposed membranes is still missing, explaining the mechanisms by which bone regeneration is reduced during membrane exposure. This scoping review comprehensively screened and discussed the current in vivo evidence and possible new perspectives on the microbial contamination of resorbable membranes. Results from eligible in vivo studies suggested that different bacterial species colonized exposed membranes according to their composition (collagen, expanded polytetrafluoroethylene (non-resorbable), and polylactic acid), but in all cases, it negatively affected the attachment level and amount of bone gain. However, limited models and techniques have evaluated the newly developed materials, and evidence is scarce. Finally, new approaches to enhance the antimicrobial effect should consider changing the membrane surface or incorporating long-term released antimicrobials in an effort to achieve better clinical success.

Recent Advances in Using Natural Antibacterial Additives in Bioactive Wound Dressings

Wound care is a global health issue with a financial burden of up to US $96.8 billion annually in the USA alone. Chronic non-healing wounds which show delayed and incomplete healing are especially problematic. Although there are more than 3000 dressing types in the wound management market, new developments in more efficient wound dressings will require innovative approaches such as embedding antibacterial additives into wound-dressing materials. The lack of novel antibacterial agents and the misuse of current antibiotics have caused an increase in antimicrobial resistance (AMR) which is estimated to cause 10 million deaths by 2050 worldwide. These ongoing challenges clearly indicate an urgent need for developing new antibacterial additives in wound dressings targeting microbial pathogens. Natural products and their derivatives have long been a significant source of pharmaceuticals against AMR. Scrutinising the data of newly approved drugs has identified plants as one of the biggest and most important sources in the development of novel antibacterial drugs. Some of the plant-based antibacterial additives, such as essential oils and plant extracts, have been previously used in wound dressings; however, there is another source of plant-derived antibacterial additives, i.e., those produced by symbiotic endophytic fungi, that show great potential in wound dressing applications. Endophytes represent a novel, natural, and sustainable source of bioactive compounds for therapeutic applications, including as efficient antibacterial additives for chronic wound dressings. This review examines and appraises recent developments in bioactive wound dressings that incorporate natural products as antibacterial agents as well as advances in endophyte research that show great potential in treating chronic wounds.

SIS membrane modification to improve antimicrobial and osteogenic properties for guide bone regeneration

The guided bone regeneration (GBR) technique is the most common and durable approach to repairing bone defects in periodontal surgery. However, membrane exposure causes bacterial infiltration, which lowers the functional integrity of the barrier membrane and destroys bone repair. Here, an antibacterial peptide-modified small intestinal submucosa (SIS) membrane is used as a new GBR membrane for effective bone regeneration. The peptide JH8194 was placed into chitosan microspheres to preserve its stability and allow for sustained release, which realizes rapid and efficient functional modification of the SIS membrane. Biocompatibility and certain antibacterial activities were found in the modified SIS membrane (SIS@CS-JH8194). Additionally, in vitro experiments showed that SIS@CS-JH8194 promoted the expression of osteogenic-related factors and decreased the secretion of inflammatory factors in rat bone mesenchymal stem cells. In vivo experiments showed that SIS@CS-JH8194 could effectively promote bone regeneration in rat skull defects. In this work, we created a new antibacterial GBR membrane to help avoid postoperative infection and improve bone tissue regeneration.

Role of Biomaterials Used for Periodontal Tissue Regeneration-A Concise Evidence-Based Review

Periodontal infections are noncommunicable chronic inflammatory diseases of multifactorial origin that can induce destruction of both soft and hard tissues of the periodontium. The standard remedial modalities for periodontal regeneration include nonsurgical followed by surgical therapy with the adjunctive use of various biomaterials to achieve restoration of the lost tissues. Lately, there has been substantial development in the field of biomaterial, which includes the sole or combined use of osseous grafts, barrier membranes, growth factors and autogenic substitutes to achieve tissue and bone regeneration. Of these, bone replacement grafts have been widely explored for their osteogenic potential with varied outcomes. Osseous grafts are derived from either human, bovine or synthetic sources. Though the biologic response from autogenic biomaterials may be better, the use of bone replacement synthetic substitutes could be practical for clinical practice. This comprehensive review focuses initially on bone graft replacement substitutes, namely ceramic-based (calcium phosphate derivatives, bioactive glass) and autologous platelet concentrates, which assist in alveolar bone regeneration. Further literature compilations emphasize the innovations of biomaterials used as bone substitutes, barrier membranes and complex scaffold fabrication techniques that can mimic the histologically vital tissues required for the regeneration of periodontal apparatus.

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

The effect of local application of thymoquinone, Nigella sativa’s bioactive component, on bone healing in experimental bone defects infected with Porphyromonas gingivalis

Purpose

This study was performed to evaluate the influence of local application of thymoquinone (TQ) on bone healing in experimental bone defects infected with Porphyromonas gingivalis (PG).

Methods

Forty-two female rats were randomly divided into 6 groups. A bone defect was created on the right tibia of all animals. The PG, PG/collagen membrane (COL) and PG/TQ/COL groups were infected with PG. In the COL and PG/COL groups, the defects were covered with a COL; in the TQ/COL and PG/TQ/COL groups, the defects were covered with a TQ-containing COL. After 28 days, all animals were sacrificed. Quantitative measurements of new bone formation and osteoblast lining, as well as semiquantitative measurements of capillary density and tissue response, were analyzed. Furthermore, the presence of bacterial infections in defect areas was evaluated.

Results

The new bone formation, osteoblast number, and capillary density were significantly higher in the TQ groups than in the control groups (P<0.001, P<0.001, and P<0.01, respectively). In a comparison between the TQ/COL group, with a TQ-containing COL (TQ/COL), and the PG–infected TQ-containing COL (PG/TQ/COL) group, the newly formed bone and capillary density were higher in the TQ/COL group (P<0.01). When the control group was compared to the PG, PG/COL, and PG/TQ/COL groups in terms of tissue response, the differences were statistically significant (P<0.001, P=0.02, and P=0.041, respectively). The intensity of the inflammatory cell reaction was higher in the PG, PG/COL, and PG/TQ/COL groups (P<0.05).

Conclusions

Within the limitations of this study, the local application of a TQ-containing COL positively affected bone healing even if the bone defects were infected. The results suggest that TQ increased angiogenesis and showed promise for accelerating bone defect healing. Further research is warranted to support these findings and reach more definitive conclusions.

Synthesis and Incorporation of Quaternary Ammonium Silane Antimicrobial into Self-Crosslinked Type I Collagen Scaffold: A Hybrid Formulation for 3D Printing

Novel 3D-biomaterial scaffold is constructed having a combination of a new quaternary ammonium silane (k21) antimicrobial impregnated in 3D collagen printed scaffolds cross linked with Riboflavin in presence of d-alpha-tocopheryl poly(ethyleneglycol)-1000-succinate. Groups of "0.1% and 0.2% k21", and "0.1% and 0.2% Chlorhexidine (CHX)" are prepared. k21/CHX with neutralized collagen is printed with BioX. Riboflavin is photo-activated and examined using epifluorescence for Aggregatibacter actinomycetemcomitans (7-days). Collagen is examined using TEM and measured for porosity, and shape-fitting. Raman and tandem mass/solid-state are performed with molecular-docking and circular-dichroism. X-ray diffractions, rheological tests, contact angle, and ninhydrin assay are conducted. k21 samples demonstrated collagen aggregates while 0.1% CHX and 0.2% CHX showed irregularities. Porosity of control and "0.1% and 0.2% k21" scaffolds show no differences. Low contact angle, improved elastic-modulus, rigidity, and smaller strain in k21 groups are seen. Bacteria are reduced and strong organic intensities are seen in k21 scaffolds. Simulation shows hydrophobicity/electrostatic interaction. Crosslinking is observed in 0.2% CHX/79% and 0.2% k21/80%. Circular dichroism for k21 are suggestive of triple helix. XRD patterns appear at d = 5.97, 3.03, 2.78, 2.1, and 2.90 A°. 3D-printing of collagen impregnated with quaternary ammonium silane produces a promising scaffold with antimicrobial potency and structural stability.

An Insight into Nano Silver Fluoride-Coated Silk Fibroin Bioinspired Membrane Properties for Guided Tissue Regeneration

The current work focuses on the development of a novel electrospun silk fibroin (SF) nonwoven mat as a GTR membrane with antibacterial, biomineralization and biocompatible properties. The γ-poly glutamic acid (γ-PGA)-capped nano silver fluoride (NSF) and silver diamine fluoride (SDF) were first synthesized, which were dip-coated onto electrospun silk fibroin mats (NSF-SF and SDF-SF). UV-Vis spectroscopy and TEM depicted the formation of silver nanoparticles. NSF-SF and SDF-SF demonstrated antibacterial properties (against Porphyromonas gingivalis) with 3.1 and 6.7 folds higher relative to SF, respectively. Post-mineralization in simulated body fluid, the NSF-SF effectively promoted apatite precipitation (Ca/P ~1.67), while the SDF-SF depicted deposition of silver nanoparticles, assessed by SEM-EDS. According to the FTIR-ATR deconvolution analysis, NSF-SF portrayed ~75% estimated hydroxyapatite crystallinity index (CI), whereas pure SF and SDF-SF demonstrated ~60%. The biocompatibility of NSF-SF was ~82% when compared to the control, while SDF-coated samples revealed in vitro cytotoxicity, further needing in vivo studies for a definite conclusion. Furthermore, the NSF-SF revealed the highest tensile strength of 0.32 N/mm and 1.76% elongation at break. Therefore, it is substantiated that the novel bioactive and antibacterial NSF-SF membranes can serve as a potential candidate, shedding light on further in-depth analysis for GTR applications.

Preventive antibiotic therapy in bone augmentation procedures in oral implantology: A systematic review

INTRODUCTION

Since the beginning of Oral Implantology, preventive antibiotic therapy has been routinely prescribed. However, at present, due to the growing appearance of antimicrobial resistance, its use has been questioned, generating a great debate and an emerging controversy. The present systematic review aims to analyze the scientific literature to determine whether the preventive prescription of antibiotics in augmentation procedures with the insertion of implants in one or two phases decreases the incidence of postoperative infections and/or the survival rate of the implants.

MATERIAL AND METHODS

The MEDLINE database was searched (via PubMed) with the following keywords: (bone grafting OR alveolar ridge augmentation OR bone graft augmentation OR guided bone regeneration OR bone block) AND (dental implants OR dental implant OR oral implantology) AND (antibiotic prophylaxis OR antibiotics). The criteria used were those described by the PRISMA® Statement. The search was limited to randomised clinical trials, systematic reviews and meta-analyses published in the last 15 years (2005-2020).

RESULTS

After reading the titles and abstracts of the resulting articles, only one systematic review meeting the described criteria and 4 randomised clinical trials were included.

CONCLUSIONS

Prescription of 2 or 3 g of amoxicillin one hour before surgery is recommended to reduce the early failure rate of one-stage implants and to decrease the bacterial load of grafted bone particles in bone augmentation procedures with one or two-stage implants.

The treatment response of barrier membrane with amoxicillin-loaded nanofibers in experimental periodontitis

BACKGROUND

Infection control is a major determinant of guided tissue regeneration (GTR). This study aims to develop an antibiotic-loaded membrane to assist periodontal repair.

METHODS

Poly(D,L-lactic acid) (PDLLA) nanofibers encapsulating amoxicillin (PDLLA-AMX) were fabricated using the electrospinning technique, and their structures, drug encapsulation efficiency, and release characteristics were assessed. The viability and behaviors of periodontal ligament (PDL) cells on nanofibers, and antibacterial capabilities of nanofibers were evaluated in vitro. Early therapeutic efficiency of the antibiotic-loaded membranes was investigated in rats with ligature-induced experimental periodontitis, and the outcomes were evaluated by gene expression, microcomputed tomography imaging, and histology within 7 days of membrane placement.

RESULTS

AMX was successfully encapsulated in the PDLLA nanofibers and released in a sustained manner. After initial attachment was achieved, cells stretched out along with the directions of nanofibers. The viability and expression of migration-associated gene of PDL cells were significantly improved, and the growth of Streptococcus sanguinis and Porphyromonas gingivalis was significantly reduced in the PDLLA-AMX group compared with the controls. On PDLLA-AMX-treated sites, wound dehiscence and sulcular inflammation were reduced. Collagen fiber matrix deposition was accelerated with upregulated type I collagen and interleukin-1β, and downregulated matrix metalloproteinase-8, whereas periodontal bone level and the expressions of vascular endothelial growth factor and core-binding factor subunit alpha-1 were equivalent to conventional membrane treatment.

CONCLUSIONS

PDLLA-AMX nanofibers inhibited bacterial growth and promoted the viability and mobility of PDL cells after initial cell attachment. Membranes with PDLLA-AMX nanofibers reduced inflammation and accelerated periodontal repair at an early stage, providing good prospects for the further development of GTR membranes.

Which substances loaded onto collagen scaffolds influence oral tissue regeneration?-an overview of the last 15 years

BACKGROUND

Collagen scaffolds are widely used for guided bone or tissue regeneration. Aiming to enhance their regenerative properties, studies have loaded various substances onto these scaffolds. This review aims to provide an overview of existing literature which conducted in vitro, in vivo, and clinical testing of drug-loaded collagen scaffolds and analyze their outcome of promoting oral regeneration.

MATERIALS AND METHODS

PubMed, Scopus, and Ovid Medline® were systematically searched for publications from 2005 to 2019. Journal articles assessing the effect of substances on oral hard or soft tissue regeneration, while using collagen carriers, were screened and qualitatively analyzed. Studies were grouped according to their used substance type-biological medical products, pharmaceuticals, and tissue-, cell-, and matrix-derived products.

RESULTS

A total of 77 publications, applying 36 different substances, were included. Collagen scaffolds were demonstrating favorable adsorption behavior and release kinetics which could even be modified. BMP-2 was investigated most frequently, showing positive effects on oral tissue regeneration. BMP-9 showed comparable results at lower concentrations. Also, FGF2 enhanced bone and periodontal healing. Antibiotics improved the scaffold's anti-microbial activity and reduced the penetrability for bacteria.

CONCLUSION

Growth factors showed promising results for oral tissue regeneration, while other substances were investigated less frequently. Found effects of investigated substances as well as adsorption and release properties of collagen scaffolds should be considered for further investigation.

CLINICAL RELEVANCE

Collagen scaffolds are reliable carriers for any of the applied substances. BMP-2, BMP-9, and FGF2 showed enhanced bone and periodontal healing. Antibiotics improved anti-microbial properties of the scaffolds.

In-vitro antibiofilm activity of chlorhexidine digluconate on polylactide-based and collagen-based membranes

Background

In Guided Tissue Regeneration (GTR), barrier membranes are used to allow selective cell populations to multiply and to promote periodontal regeneration. A frequent complication is membrane exposure to the oral cavity followed by bacterial colonization. The purpose of this in-vitro-study was to elucidate, if rinsing with a chlorhexidine digluconate solution (CHX) prevents bacterial adhesion, and whether it interferes with attachment of periodontal ligament (PDL) fibroblasts and epithelial cells to membrane surfaces.

Methods

Firstly, two bioresorbable membranes (polylactide-based and collagen-based) were dipped into 0.06% CHX and 0.12% CHX, before biofilms (2-species representing periodontal health, 6-species representing a periodontitis) were formed for 2 h and 8 h. Subsequently, colony forming units (cfu) were counted. Secondly, the membranes were treated with CHX and inoculated in bacteria suspension two-time per day for 3 d before cfu were determined. In additional series, the influence of CHX and bacterial lysates on attachment of epithelial cells and PDL fibroblasts was determined. Parameter-free tests were applied for statistical analysis.

Results

Cfu in “healthy” biofilms did not differ between the two membranes, more cfu were counted in “periodontitis” biofilm on collagen than on polylactide membranes. One-time dipping of membranes into CHX solutions did not markedly influence the cfu counts of both biofilms on polylactide membrane; those on collagen-based membrane were significantly reduced with being 0.12% CHX more active than 0.06% CHX. More-fold CHX dipping of membranes reduced concentration-dependent the cfu counts of both biofilms on both membranes. In general, the number of attached gingival epithelial cells and PDL fibroblasts was higher on collagen than on polylactide membrane. Lysates of the periodontopathogenic bacteria inhibited attachment of PDL fibroblasts to membranes. CHX decreased in a concentration-dependend manner the number of attached gingival epithelial cells and PDL fibroblasts.

Conclusions

The present in-vitro results appear to indicate that membranes in GTR should only be used when bacteria being associated with periodontal disease have been eliminated. An exposure of the membrane should be avoided. Rinsing with CHX may prevent or at least retard bacterial colonization on membrane exposed to the oral activity. However, a certain negative effect on wound healing cannot be excluded.

Guided Bone Regeneration Using BioGlue As a Barrier Material With and Without Biphasic Calcium Phosphate

The aim of this study was to investigate the effects of Bioglue as a mechanical barrier with or without biphasic calcium phosphate (BCP) in a rat tibia model. Sixty Sprague Dawley male rats weighing 250 ± 20 g and 10 to 12 weeks of age were studied. Unicortical defects were created on the right tibia of all rats. Subjects were randomly divided into 3 groups. BioGlue group (24 rats); BioGlue alone, Graft group (24 rats); BioGlue + BCP and Control group; unfilled and uncovered (12 rats). Animals were euthanized at 7th, 21st, and 45th days postoperatively for histological and histomorphometric analyses. BioGlue material exhibited no adverse effects until the end of observation period. Bone-healing scores did not differ statistically between Control and BioGlue group, but found to be lower in Graft group on 21st and 45th days, (P < 0.001 and P < 0.01 on the 21st day and P < 0.01 and P < 0.05 on the 45th day, respectively). New bone formation in Graft group was found to be statistically different from Control group on the 7th and 21st days (P < 0.01 and P < 0.05 respectively), whereas no statistical difference was observed between BioGlue and Control group at all times. The present analysis indicates that BioGlue functioned well as a mechanical barrier allowing new bone formation. No additional benefit of combination treatment was detected in this study design and BCP did not offer any advantage for bone regeneration, thus it can serve as only a space maintainer.

Early wound healing outcomes after regenerative periodontal surgery with enamel matrix derivatives or guided tissue regeneration: a systematic review

BACKGROUND

Proper wound healing after regenerative surgical procedures is an essential issue for clinical success. Guided tissue regeneration (GTR) and application of enamel matrix derivatives (EMD) are common means to regenerate periodontal tissues. Both methods bear considerable advantages due to their special characteristics, but also go along with certain disadvantages. Today, there is no consensus in the literature whether GTR or EMD show better results regarding early wound healing, which is considered a crucial stage in periodontal regeneration. Therefore, the aim of the present systematic review was to compare the early wound healing after regenerative periodontal surgery with either EMD or GTR treatment.

METHODS

An electronic literature search in PubMed was performed to identify randomized clinical trials (RCTs) or clinical trials (CTs) comparing regenerative surgery employing EMD and/or GTR in patients with chronic periodontitis. Among the finally included studies, a qualitative and quantitative data extraction regarding early wound healing parameters was performed. Primary outcome parameters were early wound healing index (EWH), flap dehiscence, membrane exposure, suppuration and abscess formation during the first 6 weeks. As secondary parameters, swelling and allergic reactions were assessed.

RESULTS

Seven studies reporting 220 intrabony periodontal defects in 199 patients were analysed. Flap dehiscence was observed in two studies in 12% of the GTR treated sites and in 10.3% of those treated with EMD. Membrane exposure was evaluated in five studies and was registered in the 28.8% of the defects, while no dehiscence was reported on the EMD group. Swelling was reported only in one study in 8/16 GTR sites and 7/16 EMD sites. Due to considerable heterogeneity of parameters no meta-analysis was possible.

CONCLUSIONS

Due to considerable heterogeneity of the published studies a clear beneficial effect of the EMD on the early wound healing outcomes after surgical treatment of periodontal intrabony defects cannot be confirmed. Standardized RCT studies are needed in order to allow for proper comparison of early wound healing after both types of surgical approaches.

Advanced smart biomaterials and constructs for hard tissue engineering and regeneration

Hard tissue repair and regeneration cost hundreds of billions of dollars annually worldwide, and the need has substantially increased as the population has aged. Hard tissues include bone and tooth structures that contain calcium phosphate minerals. Smart biomaterial-based tissue engineering and regenerative medicine methods have the exciting potential to meet this urgent need. Smart biomaterials and constructs refer to biomaterials and constructs that possess instructive/inductive or triggering/stimulating effects on cells and tissues by engineering the material's responsiveness to internal or external stimuli or have intelligently tailored properties and functions that can promote tissue repair and regeneration. The smart material-based approaches include smart scaffolds and stem cell constructs for bone tissue engineering; smart drug delivery systems to enhance bone regeneration; smart dental resins that respond to pH to protect tooth structures; smart pH-sensitive dental materials to selectively inhibit acid-producing bacteria; smart polymers to modulate biofilm species away from a pathogenic composition and shift towards a healthy composition; and smart materials to suppress biofilms and avoid drug resistance. These smart biomaterials can not only deliver and guide stem cells to improve tissue regeneration and deliver drugs and bioactive agents with spatially and temporarily controlled releases but can also modulate/suppress biofilms and combat infections in wound sites. The new generation of smart biomaterials provides exciting potential and is a promising opportunity to substantially enhance hard tissue engineering and regenerative medicine efficacy.

Synthesis and characterization of CaO-loaded electrospun matrices for bone tissue engineering

OBJECTIVES

This study aims to synthesize and characterize biodegradable polymer-based matrices loaded with CaO nanoparticles for osteomyelitis treatment and bone tissue engineering.

MATERIALS AND METHODS

Poly(ε-caprolactone) (PCL) and PCL/gelatin (1:1, w/w) solutions containing CaO nanoparticles were electrospun into fibrous matrices. Scanning (SEM) and transmission (TEM) electron microscopy, Fourier transformed infrared (FTIR), energy dispersive X-ray spectroscopy (EDS), contact angle (CA), tensile testing, and antibacterial activity (agar diffusion assay) against Staphylococcus aureus were performed. Osteoprecursor cell (MC3T3-E1) response (i.e., viability and alkaline phosphatase expression/ALP) and infiltration into the matrices were evaluated.

RESULTS

CaO nanoparticles were successfully incorporated into the fibers, with the median fiber diameter decreasing after CaO incorporation. The CA decreased with the addition of CaO, and the presence of gelatin made the matrix very hydrophilic (CA = 0°). Increasing CaO concentrations progressively reduced the mechanical properties (p ≤ 0.030). CaO-loaded matrices did not display consistent antibacterial activity. MC3T3-E1 cell viability demonstrated the highest levels for CaO-loaded matrices containing gelatin after 7 days in culture. An increased ALP expression was consistently seen for PCL/CaO matrices when compared to PCL and gelatin-containing counterparts.

CONCLUSIONS

Despite inconsistent antibacterial activity, CaO nanoparticles can be effectively loaded into PCL or PCL/gelatin fibers without negatively affecting the overall performance of the matrices. More importantly, CaO incorporation enhanced cell viability as well as differentiation capacity, as demonstrated by an increased ALP expression.

CLINICAL SIGNIFICANCE

CaO-loaded electrospun matrices show potential for applications in bone tissue engineering.