Periodontal tissue engineering by growth factors

Supra-Alveolar Bone Regeneration: Progress, Challenges, and Future Perspectives

Periodontitis is a highly prevalent disease that damages the supporting tissues of a tooth, including the alveolar bone. Alveolar bone loss owing to periodontitis is broadly categorized as supra-alveolar and intra-alveolar bone loss. In intra-alveolar bone loss, the defect has an angular or oblique orientation to the long axis of the tooth in an apical direction. In contrast, the defect is perpendicular to the long axis of the tooth in supra-alveolar bone loss. Unlike intra-alveolar bone defects, supra-alveolar bone defects lack supporting adjacent space, which makes supra-alveolar bone regeneration more challenging. In addition, the limited availability of resources in terms of vascularity and underlying tissues is another obstacle to supra-alveolar bone regeneration. Currently, supra-alveolar bone loss is the least predictable periodontal defect type in regenerative periodontal therapy. In addition, supra-alveolar bone loss is much more common than other alveolar bone loss. Despite its prevalence, research on supra-alveolar bone regeneration remains sparse, indicating an unmet need for significant research efforts in this area. This review summarize recent advances, obstacles, and future directions in the field of supra-alveolar bone regeneration. We discuss the biomaterials, bioactive molecules, and cells that have been tested for supra-alveolar bone regeneration, followed by pre-clinical and clinical approaches employed in this field. Additionally, we highlight obstacles and present future directions that will propel supra-alveolar bone research forward.

Twenty-five years of recombinant human growth factors rhPDGF-BB and rhBMP-2 in oral hard and soft tissue regeneration

Contemporary oral tissue engineering strategies involve recombinant human growth factor approaches to stimulate diverse cellular processes including cell differentiation, migration, recruitment, and proliferation at grafted areas. Recombinant human growth factor applications in oral hard and soft tissue regeneration have been progressively researched over the last 25 years. Growth factor-mediated surgical approaches aim to accelerate healing, tissue reconstruction, and patient recovery. Thus, regenerative approaches involving growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF-BB) and recombinant human bone morphogenetic proteins (rhBMPs) have shown certain advantages over invasive traditional surgical approaches in severe hard and soft tissue defects. Several clinical studies assessed the outcomes of rhBMP-2 in diverse clinical applications for implant site development and bone augmentation. Current evidence regarding the clinical benefits of rhBMP-2 compared to conventional therapies is inconclusive. Nevertheless, it seems that rhBMP-2 can promote faster wound healing processes and enhance de novo bone formation, which may be particularly favorable in patients with compromised bone healing capacity or limited donor sites. rhPDGF-BB has been extensively applied for periodontal regenerative procedures and for the treatment of gingival recessions, showing consistent and positive outcomes. Nevertheless, current evidence regarding its benefits at implant and edentulous sites is limited. The present review explores and depicts the current applications, outcomes, and evidence-based clinical recommendations of rhPDGF-BB and rhBMPs for oral tissue regeneration.

Current Progress of Platelet-Rich Derivatives in Cartilage and Joint Repairs

In recent years, several types of platelet concentrates have been investigated and applied in many fields, particularly in the musculoskeletal system. Platelet-rich fibrin (PRF) is an autologous biomaterial, a second-generation platelet concentrate containing platelets and growth factors in the form of fibrin membranes prepared from the blood of patients without additives. During tissue regeneration, platelet concentrates contain a higher percentage of leukocytes and a flexible fibrin net as a scaffold to improve cell migration in angiogenic, osteogenic, and antibacterial capacities during tissue regeneration. PRF enables the release of molecules over a longer period, which promotes tissue healing and regeneration. The potential of PRF to simulate the physiology and immunology of wound healing is also due to the high concentrations of released growth factors and anti-inflammatory cytokines that stimulate vessel formation, cell proliferation, and differentiation. These products have been used safely in clinical applications because of their autologous origin and minimally invasive nature. We focused on a narrative review of PRF therapy and its effects on musculoskeletal, oral, and maxillofacial surgeries and dermatology. We explored the components leading to the biological activity and the published preclinical and clinical research that supports its application in musculoskeletal therapy. The research generally supports the use of PRF as an adjuvant for various chronic muscle, cartilage, and tendon injuries. Further clinical trials are needed to prove the benefits of utilizing the potential of PRF.

The role of rhFGF-2 in periodontal defect bone fill: A systematic review of the literature

BACKGROUND

Growth factors have been used with success in periodontal regeneration, especially in intrabony defects. Among those, the recombined form of fibroblast growth factor-2 (rhFGF-2) has been also examined.

OBJECTIVE

To address the outcomes of periodontal regeneration using rhFGF-2 alone or in combination with bone substitutes primarily in terms of Radiographic Bone Fill (RBF%) and secondary Probing Pocket Depth (PPD), and Probing Attachment Levels (PAL).

MATERIAL AND METHODS

A search in MEDLINE and EMBASE using the Ovid interface was conducted from 2000 up to and including the 12th of November 2022. Starting from the initially identified 1289 articles, 34 studies were selected for further analysis. Following the full-text screening, 7 of the 34 studies met the inclusion criteria and thus were included in the systematic review after assessing their quality according to the Newcastle-Ottawa scale (NOS). Clinical and radiographic results (bone gain, pocket depth, and clinical attachment level) after the application of FGF-2 alone or in combination with different carriers were studied in patients with intrabony defects of at least one wall and pocket depth greater than 4 mm.

RESULTS

Primary outcomes: RBF% was higher in studies using a combination of rhFGF-2 and bone substitutes (74.6 ± 20.0%) compared to others using the specific growth factor alone or negative controls (22.7 ± 20.7%). In terms of secondary outcomes, the analysis failed to show an additional benefit from the use of the rhFGF-2 alone or in combination with bone substitutes.

CONCLUSION

rhFGF-2 can improve RBF% in the treatment of periodontal defects, especially when it is used in combination with a bone substitute.

Application of Biocompatible Scaffolds in Stem-Cell-Based Dental Tissue Engineering

Tissue engineering as an important field in regenerative medicine is a promising therapeutic approach to replace or regenerate injured tissues. It consists of three vital steps including the selection of suitable cells, formation of 3d scaffolds, and adding growth factors. Mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs) are mentioned as two main sources for this approach that have been used for the treatment of various types of disorders. However, the main focus of literature in the field of dental tissue engineering is on utilizing MSCs. On the other hand, biocompatible scaffolds play a notable role in this regenerative process which is mentioned to be harmless with acceptable osteoinductivity. Their ability in inhibiting inflammatory responses also makes them powerful tools. Indeed, stem cell functions should be supported by biomaterials acting as scaffolds incorporated with biological signals. Naturally derived polymeric scaffolds and synthetically engineered polymeric/ceramic scaffolds are two main types of scaffolds regarding their materials that are defined further in this review. Various strategies of tissue bioengineering can affect the regeneration of dentin-pulp complex, periodontium regeneration, and whole teeth bioengineering. In this regard, in vivo/ex vivo experimental models have been developed recently in order to perform preclinical studies of dental tissue engineering which make it more transferable to be used for clinic uses. This review summarizes dental tissue engineering through its different components. Also, strategies of tissue bioengineering and experimental models are introduced in order to provide a perspective of the potential roles of dental tissue engineering to be used for clinical aims.

Efficacy of bone graft as monotherapy and in combination with platelet concentrates in grade II furcation defect - A systematic review and meta-analysis

Background

The use of autologous platelet concentrates (PC) in addition to bone graft (BG) in open flap debridement (OFD) has been investigated to improve the efficacy and outcomes of regenerative therapy for furcation defects. This systematic review evaluated efficacy of added benefits of PC to bone grafts in treatment of grade II furcation defects.

Methods

A thorough literature search on PubMed, Cochrane Library and Google Scholar databases was conducted. Data on outcomes were extracted only from randomized controlled clinical trials on humans with a minimum follow up of 6 months comparing BG alone and BG + PC in treatment of mandibular grade II furcation defect.

Results

36 of the 518 screened articles and abstracts were read in full-text, nine of which have been included in the meta-analysis. The addition of PC to BG has resulted in improvement in PD, GR (with smaller effect); V-DBD and H-DBD showed smaller change in experimental group whereas VCAL and HCAL exhibited overall larger changes with smaller effect.

Conclusion

Bone regeneration in terms of defect fill with the addition of platelet concentrates to bone graft remains debatable considering the minimal benefits in the treatment of grade II mandibular furcation defect.

Polymeric Nanotechnologies for the Treatment of Periodontitis: A Chronological Review

Periodontitis is a chronic infectious and inflammatory disease of periodontal tissues estimated to affect 70 - 80 % of all adults. At the same time, periodontium, the site of periodontal pathologies, is an extraordinarily complex plexus of soft and hard tissues, the regeneration of which using even the most advanced forms of tissue engineering continues to be a challenge. Nanotechnologies, meanwhile, have provided exquisite tools for producing biomaterials and pharmaceutical formulations capable of elevating the efficacies of standard pharmacotherapies and surgical approaches to whole new levels. A bibliographic analysis provided here demonstrates a continuously increasing research output of studies on the use of nanotechnologies in the management of periodontal disease, even when they are normalized to the total output of studies on periodontitis. The great majority of biomaterials used to tackle periodontitis, including those that pioneered this interesting field, have been polymeric. In this article, a chronological review of polymeric nanotechnologies for the treatment of periodontitis is provided, focusing on the major conceptual innovations since the late 1990s, when the first nanostructures for the treatment of periodontal diseases were fabricated. In the opening sections, the etiology and pathogenesis of periodontitis and the anatomical and histological characteristics of the periodontium are being described, along with the general clinical manifestations of the disease and the standard means of its therapy. The most prospective chemistries in the design of polymers for these applications are also elaborated. It is concluded that the amount of innovation in this field is on the rise, despite the fact that most studies are focused on the refinement of already established paradigms in tissue engineering rather than on the development of revolutionary new concepts.

Extracellular Matrix-Oriented Proteomic Analysis of Periodontal Ligament Under Mechanical Stress

The periodontal ligament (PDL) is a specialized connective tissue that provides structural support to the tooth and is crucial for oral functions. The mechanical properties of the PDL are mainly derived from the tissue-specific composition and structural characteristics of the extracellular matrix (ECM). The ECM also plays key roles in determining cell fate in the cellular microenvironment thus crucial in the PDL tissue homeostasis. In the present study, we determined the comprehensive ECM profile of mouse molar PDL using laser microdissection and mass spectrometry-based proteomic analysis with ECM-oriented data curation. Additionally, we evaluated changes in the ECM proteome under mechanical loading using a mouse orthodontic tooth movement (OTM) model and analyzed potential regulatory networks using a bioinformatics approach. Proteomic changes were evaluated in reference to the novel second harmonic generation (SHG)-based fiber characterization. Our ECM-oriented proteomics approach succeeded in illustrating the comprehensive ECM profile of the mouse molar PDL. We revealed the presence of type II collagen in PDL, possibly associated with the load-bearing function upon occlusal force. Mechanical loading induced unique architectural changes in collagen fibers along with dynamic compositional changes in the matrisome profile, particularly involving ECM glycoproteins and matrisome-associated proteins. We identified several unique matrisome proteins which responded to the different modes of mechanical loading in PDL. Notably, the proportion of type VI collagen significantly increased at the mesial side, contributing to collagen fibrogenesis. On the other hand, type XII collagen increased at the PDL-cementum boundary of the distal side. Furthermore, a multifaceted bioinformatics approach illustrated the potential molecular cues, including PDGF signaling, that maintain ECM homeostasis under mechanical loading. Our findings provide fundamental insights into the molecular network underlying ECM homeostasis in PDL, which is vital for clinical diagnosis and development of biomimetic tissue-regeneration strategies.

Periodontal Wound Healing and Regeneration: Insights for Engineering New Therapeutic Approaches

Periodontitis is a widespread inflammatory disease that leads to loss of the tooth supporting periodontal tissues. The few therapies available to regenerate periodontal tissues have high costs and inherent limitations, inspiring the development of new approaches. Studies have shown that periodontal tissues have an inherent capacity for regeneration, driven by multipotent cells residing in the periodontal ligament (PDL). The purpose of this review is to describe the current understanding of the mechanisms driving periodontal wound healing and regeneration that can inform the development of new treatment approaches. The biologic basis underlying established therapies such as guided tissue regeneration (GTR) and growth factor delivery are reviewed, along with examples of biomaterials that have been engineered to improve the effectiveness of these approaches. Emerging therapies such as those targeting Wnt signaling, periodontal cell delivery or recruitment, and tissue engineered scaffolds are described in the context of periodontal wound healing, using key in vivo studies to illustrate the impact these approaches can have on the formation of new cementum, alveolar bone, and PDL. Finally, design principles for engineering new therapies are suggested which build on current knowledge of periodontal wound healing and regeneration.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.

The effects of lyophilised platelet-rich plasma in third molar extraction sockets and its surrounding tissues

Objective

To determine the effects of repeated placement of quantified lyophilised platelet-rich plasma (LPRP) on the soft and hard tissue components.

Methods

Lyophilised platelet-rich plasma was topically placed, and later injected, into fresh sockets using the third molar surgical model, randomised according to the split-mouth approach. The control site received placebo. The application of LPRP was done intraoperatively, one month and two months postoperatively. The measured endpoints included post-operative pain, swelling, trismus, pocket depth at mid-distal adjacent second molar, soft tissue healing, and bone formation (which was assessed radiographically). Fifteen healthy young adults, aged between 21 and 35 years, visiting the Oral and Maxillofacial Surgery Clinic at the University of Malaya were recruited for this study.

Results

There was no significant difference in post-operative pain, swelling size, trismus, and bone healing within their specific timelines during this study. However, the LPRP group showed significant reduction in pocket depth at the two-month post-operative period, suggesting that LPRP improves soft tissue healing.

Conclusion

Soft tissue healing, measured as the change of periodontal pocket depth, showed significant reduction, suggesting the benefit of LPRP for soft tissue healing. However, bone regeneration and reduction of post-operative sequelae showed no improvement even after quantification and repeated LPRP application.

Chondrogenic Potential of Human Dental Pulp Stem Cells Cultured as Microtissues

Several tissue engineering stem cell-based procedures improve hyaline cartilage repair. In this work, the chondrogenic potential of dental pulp stem cell (DPSC) organoids or microtissues was studied. After several weeks of culture in proliferation or chondrogenic differentiation media, synthesis of aggrecan and type II and I collagen was immunodetected, and SOX9, ACAN, COL2A1, and COL1A1 gene expression was analysed by real-time RT-PCR. Whereas microtissues cultured in proliferation medium showed the synthesis of aggrecan and type II and I collagen at the 6^th week of culture, samples cultured in chondrogenic differentiation medium showed an earlier and important increase in the synthesis of these macromolecules after 4 weeks. Gene expression analysis showed a significant increase of COL2A1 after 3 days of culture in chondrogenic differentiation medium, while COL1A1 was highly expressed after 14 days. Cell-cell proximity promotes the chondrogenic differentiation of DPSCs and important synthesis of hyaline chondral macromolecules.

Recombinant Human Derived Growth and Differentiating Factors in treatment of periodontal intrabony defects: Systematic review and network meta-analysis

The introduction of recombinant human growth and differentiation factors (rhGFs) for intrabony defects regeneration has represented a considerable breakthrough in recent years. However, they have been used in different concentrations, doses and combined with various scaffolds, and there is no evidence on which the most effective formulation for periodontal regeneration is. Therefore, we aimed to evaluate and rank the various formulations of such bioactive agents through network meta-analysis of clinical studies. The protocol registration was done on PROSPERO with registration ID CRD42020213753. To report NMA, we followed PRISMA guidelines and searched PUBMED, Embase, Web of Science and Cochrane Central electronic databases. Studies were screened based on specific inclusion criteria. Primary outcomes extracted from included studies were the most common indexes for periodontal regeneration (PPD, CAL, %bone filling). The NMA analysis included network plots, contribution plots, inconsistency plots (if eligible to form the loop), predictive interval plots, SUCRA rankings and multidimensional scale ranking (MDS) plots. SUCRA would demonstrate the rankings of multiple competing bioactive agents based on their best performance. Twelve clinical studies for qualitative and quantitative analysis were considered. Network meta-analysis found that rhFGF + hydroxyapatite was ranked highest in PPD and CAL outcome. rhPDGF-BB+β-tricalcium phosphate was ranked highest in the percentage of bone filling. In addition, all bioactive agents performed better than control groups without rhGFs. Despite clear benefits deriving from rhGFs for periodontal regeneration, the present results should be interpreted with caution due to several confounding factors affecting the outcome. Nevertheless, further well designed randomized clinical trials will allow establishing guidelines for an appropriate indication of the use of rhGFs.

Biomaterials for Periodontal and Peri-Implant Regeneration

Periodontal and peri-implant regeneration is the technique that aims to restore the damaged tissue around teeth and implants. They are surrounded by a different apparatus, and according to it, the regenerative procedure can differ for both sites. During the last century, several biomaterials and biological mediators were proposed to achieve a complete restoration of the damaged tissues with less invasiveness and a tailored approach. Based on relevant systematic reviews and articles searched on PubMed, Scopus, and Cochrane databases, data regarding different biomaterials were extracted and summarized. Bone grafts of different origin, membranes for guided tissue regeneration, growth factors, and stem cells are currently the foundation of the routinary clinical practice. Moreover, a tailored approach, according to the patient and specific to the involved tooth or implant, is mandatory to achieve a better result and a reduction in patient morbidity and discomfort. The aim of this review is to summarize clinical findings and future developments regarding grafts, membranes, molecules, and emerging therapies. In conclusion, tissue engineering is constantly evolving; moreover, a tailor-made approach for each patient is essential to obtain a reliable result and the combination of several biomaterials is the elective choice in several conditions.

Regenerative periodontal therapy: I part

Introduction: Under the concept of regenerative periodontal therapy, there are two approaches: the first is the passive regeneration conceptthat includes bone substituents and guided periodontal regeneration by using of biomembranes and the second concept of active regeneration that impliesthe use of growth factors. The aim of the passive regeneration, by using of bone matrix (bone substituens) has been stabilization and bone defects management, preventing epithelial tissue growth, as well as saving space for the new tissue regeneration. This concept implies the use of autogenous transplantats, xenografts, allografts, as well as alloplastic materials. The carriers for active tissue regeneration, growth factors -GF are biological mediators that regulate cellular processes and that is crucial for the tissue regeneration. Aim:Presentation ofmodern approaches to periodontal therapy thatare focused on the attachment regeneration and complete reconstruction of periodontal tissue. Conclusion: In the future, periodontal regenerative therapy with periodontalligament progenitor cells should encourage repopulation of the areas that have been affected by periodontal disease.

Innovative use of increasing the width of attached gingiva using chorion membrane along with platelet rich fibrin membrane

Width of attached gingiva plays an important role in maintaining periodontal health, provides stabilization of the gingival margin against frictional forces and aids in dissipating physiological forces exerted by the muscular fibers of the alveolar mucosa on the gingival tissues. Inadequate width of attached gingiva leads to attachment loss, soft tissue recession, and impedes oral hygiene measures. Hence, procedures using autografts and allografts have been proposed to augment the attached gingiva. Allografts like chorionic membrane (CM) are known to enhance release of growth factors, promote neovascularization, healing and enhance biotype. To assess the efficacy of CM in increasing the width of attached gingiva, vestibular depth and gingival thickness. Fifteen patients with inadequate attached gingival width were included in the study. Patients were randomly allocated to each group: Control group, CM group and CM + platelet rich fibrin (PRF) group. Attached gingiva width, vestibular depth, and gingival thickness were measured at baseline and 4 weeks post procedure. The control, CM and CM + PRF groups showed an increase in all parameters from baseline to 4 weeks. The increase in the attached gingiva (p = 0.042) width, vestibular depth (p = 0.043) and gingival thickness (p = 0.034) were statistically significant at 4 weeks for CM group and CM + PRF group respectively. The CM + PRF group showed better results compared to other groups. CM and PRF can be effectively incorporated to increase the width of attached gingiva and depth of vestibule.

Expression of Vascular Endothelial Growth Factor Using Platelet Rich Fibrin (PRF) and Nanohydroxyapatite (nano-HA) in Treatment of Periodontal Intra-Bony Defects - A Randomized Controlled Trial

The study aims to assess the concentration of vascular endothelial growth factors (VEGF) with platelet rich fibrin (PRF) biomaterial, while using it separately or in combination with nanohydroxyapatite (nano-HA) for treating intra-bony defects (IBDs) using radiographic evaluation (DBS-Win software). Sixty patients with IBD (one site/patient) and chronic periodontitis were recruited randomly to test either autologous PRF platelet concentrate, nano-HA bone graft, a combination of PRF platelet concentrate and nano-HA, or alone conventional open flap debridement (OFD). Recordings of clinical parameters including probing depth (PD), gingival index (GI), and clinical attachment level (CAL) were obtained at baseline and 6 months, post-operatively. One-way analysis of variance (ANOVA) was used to compare four groups; whereas, multiple comparisons were done through Tukey’s post hoc test. The results showed that CAL at baseline changed from 6.67 ± 1.23 to 4.5 ± 1.42 in group I, 6.6 ± 2.51 to 4.9 ± 1.48 in group II, 5.2 ± 2.17 to 3.1 ± 1.27 in group III, and 4.7 ± 2.22 to 3.7 ± 2.35 in group IV after 6 months. The most significant increase in bone density and fill was observed for IBD depth in group III that was recorded as 62.82 ± 24.6 and 2.31 ± 0.75 mm, respectively. VEGF concentrations were significantly increased at 3, 7, and 14 days in all groups. The use of PRF with nano-HA was successful regenerative periodontal therapy to manage periodontal IBDs, unlike using PRF alone. Increase in VEGF concentrations in all group confirmed its role in angiogenesis and osteogenesis in the early stages of bone defect healing.

Adsorption and Release of Growth Factors from Four Different Porcine-Derived Collagen Matrices

Xenogeneic acellular collagen matrices represent a safe alternative to autologous soft tissue transplants in periodontology and implant dentistry. Here, we aimed to investigate the adsorption and release of growth factors from four porcine-derived collagen matrices using enzyme-linked immunosorbent assay. Non-crosslinked collagen matrix (NCM), crosslinked collagen matrix (CCM), dried acellular dermal matrix (DADM), and hydrated acellular dermal matrix (HADM) adsorbed each of the following growth factors, TGF-β1, FGF-2, PDGF-BB, GDF-5 and BMP-2, with an efficiency close to 100%. Growth factor release for a 13-day period was in the range of 10-50% of the adsorbed protein, except for the BMP-2 release that was in the range of 5-7%. Generally, protein release occurred in two phases. Phase I was arbitrary defined by the highest release from the matrices, usually within 24 h. Phase II, spanning the period immediately after the peak release until day 13, corresponded to the delayed release of the growth factors from the deeper layers of the matrices. HADM showed significantly (P < 0.001) higher TGF-β1, FGF-2, and PDGF-BB release in phase II, compared to the rest of the matrices. NCM exhibited significantly (P < 0.001) higher FGF-2 release in phase II, compared to CCM and DADM as well as a characteristic second peak in PDGF-BB release towards the middle of the tested period. In contrast to NCM and HADM, CCM and DADM showed a gradual and significantly higher release of GDF-5 in the second phase. Several burst releases of BMP-2 were characteristic for all matrices. The efficient adsorption and sustained protein release in the first 13 days, and the kinetics seen for HADM, with a burst release within hours and high amount of released growth factor within a secondary phase, may be beneficial for the long-term tissue regeneration following reconstructive periodontal surgery.

Platelet derived growth factor-BB levels in gingival crevicular fluid of localized intrabony defect sites treated with platelet rich fibrin membrane or collagen membrane containing recombinant human platelet derived growth factor-BB: A randomized clinical and biochemical study

BACKGROUND

Development of autologous and recombinant growth factor/matrix combination products represent a new emerging trend in regenerative therapeutics and have gained increasing attention as a strategy to optimize tissue regeneration. The aim of the present study was to evaluate the levels of platelet derived growth factor-BB (PDGF-BB) in gingival crevicular fluid (GCF) during early healing period after the regenerative treatment of intrabony defects using beta tricalcium phosphate (β-TCP) as a bone regeneration material with either platelet rich fibrin (PRF) membrane or collagen membrane (CM) treated with recombinant human PDGF-BB (rhPDGF-BB).

METHODS

Twenty patients (13 males and 7 females) with chronic periodontitis participated in this prospective, randomized clinical and biochemical study. Each patient was randomly assigned to PRF membrane (group A) or CM incorporated with rhPDGF-BB (group B). GCF samples were obtained on days 3, 7, 14, and 30 for evaluation of PDGF-BB levels and alkaline phosphatase (ALP) levels.

RESULTS

On days 3 and 7 following surgery, mean levels of PDGF-BB at sites treated with PRF membrane or CM incorporated with rhPDGF-BB as a barrier membrane were not significantly different. PDGF-BB levels decreased significantly in samples collected on days 14 and 30 with significant differences between both the groups. ALP levels significantly increased from day 3 to day 30 but there was no difference between two groups.

CONCLUSION

Within the limitations of the study, both PRF membrane and CM incorporated with rhPDGF-BB showed comparable GCF levels of PDGF-BB initially with PRF showing more sustained levels throughout the study period.

Biomaterials, Current Strategies, and Novel Nano-Technological Approaches for Periodontal Regeneration

Periodontal diseases involve injuries to the supporting structures of the tooth and, if left untreated, can lead to the loss of the tooth. Regenerative periodontal therapies aim, ideally, at healing all the damaged periodontal tissues and represent a significant clinical and societal challenge for the current ageing population. This review provides a picture of the currently-used biomaterials for periodontal regeneration, including natural and synthetic polymers, bioceramics (e.g., calcium phosphates and bioactive glasses), and composites. Bioactive materials aim at promoting the regeneration of new healthy tissue. Polymers are often used as barrier materials in guided tissue regeneration strategies and are suitable both to exclude epithelial down-growth and to allow periodontal ligament and alveolar bone cells to repopulate the defect. The problems related to the barrier postoperative collapse can be solved by using a combination of polymeric membranes and grafting materials. Advantages and drawbacks associated with the incorporation of growth factors and nanomaterials in periodontal scaffolds are also discussed, along with the development of multifunctional and multilayer implants. Tissue-engineering strategies based on functionally-graded scaffolds are expected to play an ever-increasing role in the management of periodontal defects.

The Combined Effect of Bioactive Glass and Platelet-Rich Fibrin in Treating Human Periodontal Intrabony Defects - A Clinicoradiographic Study

Background:

Platelets are richest source for cytokine and growth factors which are two important components for the re-establishment of bone and maturation of the soft tissue.

Aims and Objective:

The additive effect of PRF along with a synthetic bone graft material in treating human intrabony periodontal defects has been evaluated in this study. The appropriate use of platelet-rich fibrin (PRF) as an alternate comfortable graft material to restore the lost periodontal tissues has been well documented and has given clinically promising outcome.

Materials and Method:

Platelet-rich fibrin (PRF) is prepared from patient's own blood which is autologous in nature. Perio Glas (PG) is an easy to use synthetic absorbable osteostimulative as well as osteoconductive bone graft material. The selected 30 sites were randomly divided into two groups such as Test (15 sites using PRF) and Control (15 sites without PRF).

Results:

At the end of Six months, the post-operative evaluations revealed significant reduction in PPD and gain in CAL. Radiographic evidence of bone formation was also noticed. The incorporation of PRF with synthetic bone graft (perioglas) produces effective and rapid periodontal regeneration with improved healing in intrabony osseous defects. The PRF group showed a mean Radiographic Defect Fill (RDL) of 1.24 ± 0.04 compared with 0.79 ± 0.07 of control group which is statistically significant.

Conclusion:

This combination technique can be used as an alternate grafting modality for the treatment of intrabony periodontal defects with satisfactory clinical consequences.

Maxillary Sinus Augmentation for Dental Implant Rehabilitation of the Edentulous Ridge: A Comprehensive Overview of Systematic Reviews

OBJECTIVES

The objective of this systemic review was to perform a comprehensive overview of systematic reviews and meta-analyses of the maxillary sinus augmentation procedure for implant rehabilitation in humans. The following were evaluated in this overview: (1) anatomic variables affecting sinus augmentation, (2) histomorphometric analysis of the grafted sinus, (3) volumetric changes after sinus grafting, and (4) implant survival beyond 1 year.

MATERIAL AND METHODS

Electronic databases were searched for systematic reviews and meta-analyses of implant-related sinus augmentation published from 1976 to September 2015. The studies selected must identify itself as a systemic review or meta-analysis in the title or abstract and must pertain to sinus augmentation.

RESULTS

Thirty-three publications fulfilled the review criteria. The AMSTAR ratings for the 33 chosen reviews scored greater than 3 of 11, with 8 reviews scoring greater or equal to 8 of 11.

CONCLUSION

The outcome of this overview suggested that the following will increase the success of sinus augmentation and survival of implants placed in the grafted sinus: (1) the use of barrier membranes over the lateral window when using a lateral approach to graft the sinus, (2) the use of particulate autogenous bone with or without other substitute graft materials, (3) sinus augmentation without the use of grafting materials may be considered provided that the space between the sinus membrane and floor can be maintained, (4) the use of rough-surfaced implants, (5) simultaneous implant placement with residual bone height greater than 4 mm, and (6) the cessation of smoking.

Platelet-rich Fibrin: A Paradigm in Periodontal Therapy - A Systematic Review

Periodontal tissue regeneration has always been a challenge for the periodontists owing to its structural complexity. Although with tissue engineering as a growing multidisciplinary field, this aim has partially been fulfilled. In recent years, platelet-rich fibrin (PRF) has gained wide attention for its utilization as a biocompatible regenerative material not only in dental but also in medical fields. The following systematic review has gathered all the currently available in vitro, animal, and clinical studies utilizing PubMed electronic database from January 2006 to August 2016 highlighting PRF for soft and hard tissue regeneration and/or wound healing. Although results are encouraging but require further validation from clinical studies to justify the potential role of PRF in periodontal regeneration so that this relatively inexpensive autologous biomaterial can be utilized at a wider scale.

Additive Effect of Plasma Rich in Growth Factors With Guided Tissue Regeneration in Treatment of Intrabony Defects in Patients With Chronic Periodontitis: A Split-Mouth Randomized Controlled Clinical Trial

BACKGROUND

Periodontal regeneration can be defined as complete restoration of lost periodontal tissues to their original architecture and function. A variety of treatment modalities have been proposed to achieve it. Plasma rich in growth factors (PRGF) is a concentrated suspension of growth factors that promotes restoration of lost periodontal tissues. The objective of the present study is to assess the effect of PRGF associated with guided tissue regeneration (GTR) versus GTR only in the treatment of intrabony defects (IBDs) in patients with chronic periodontitis (CP).

METHODS

Patients with CP (n = 14) with 42 contralateral 2- and 3-walled defects were randomly assigned to test (PRGF+GTR) and control (GTR alone) treatment groups. Clinical and radiographic assessments performed at baseline and after 6 months were: 1) gingival index (GI), 2) probing depth (PD), 3) clinical attachment level (CAL), 4) radiologic defect depth, and 5) bone fill.

RESULTS

Comparison of parameters measured at baseline and after 6 months showed mean PD reduction of 3.37 ± 1.62 mm in the control group (P <0.001) and 4.13 ± 1.59 mm in the test group (P <0.001). There was a significant difference in mean change in CAL (P <0.001) in the control group (5.42 ± 1.99) and the test group (5.99 ± 1.77). Mean change in GI was 1.89 ± 0.32 and 1.68 ± 0.58 in the control group and test group, respectively, and the difference was statistically significant (P <0.001). When compared between groups, clinical parameters did not show any statistically significant variations. Mean radiographic bone fill was 1.06 ± 0.81 and 1.0 ± 0.97 in the control group and test group, respectively. However, the difference was not statistically significant.

CONCLUSIONS

PRGF with GTR, as well as GTR alone, was effective in improving clinical and radiographic parameters of patients with CP at the 6-month follow-up. There was no additive effect of PRGF when used along with GTR in the treatment of IBDs in patients with CP in terms of both clinical and radiologic outcomes.

Analysis of gene expression profiles between apical papilla tissues, stem cells from apical papilla and cell sheet to identify the key modulators in MSCs niche

OBJECTIVES

The microenvironmental niche plays the key role for maintaining the cell functions. The stem cells from apical papilla (SCAPs) are important for tooth development and regeneration. However, there is limited knowledge about the key factors in niche for maintaining the function of SCAPs. In this study, we analyse the gene expression profiles between apical papilla tissues, SCAPs and SCAPs cell sheet to identify the key genes in SCAPs niche.

MATERIALS AND METHODS

Microarray assays and bioinformatic analysis were performed to screen the differential genes between apical papilla tissues and SCAPs, and SCAPs and SCAPs cell sheet. Recombinant human BMP6 protein was used in SCAPs. Then CCK-8 assay, CFSE assay, alkaline phosphatase activity, alizarin red staining, quantitative calcium analysis and real-time reverse transcriptase-polymerase chain reaction were performed to investigate the cell proliferation and differentiation potentials of SCAPs.

RESULTS

Microarray analysis found that 846 genes were up-regulated and 1203 genes were down-regulated in SCAPs compared with apical papilla tissues. While 240 genes were up-regulated and 50 genes were down-regulated in SCAPs compared to in SCAPs cell sheet. Moreover, only 31 gene expressions in apical papilla tissues were recovered in cell sheet compared with SCAPs. Bioinformatic analysis identified that TGF-β, WNT and MAPK signalling pathways may play an important role in SCAPs niche. Based on the analysis, we identified one key growth factor in niche, BMP6, which could enhance the cell proliferation, the osteo/dentinogenic, neurogenic and angiogenic differentiation potentials of SCAPs.

CONCLUSIONS

Our results provided insight into the mechanisms of the microenvironmental niche which regulate the function of SCAPs, and identified the key candidate genes in niche to promote mesenchymal stem cells-mediated dental tissue regeneration.

Three-dimensional structure and cytokine distribution of platelet-rich fibrin

OBJECTIVES:

Previous reports have revealed that several cytokines (including platelet-derived growth factor-BB, transforming growth factors-β1 and insulin-like growth factor-1) can enhance the rate of bone formation and synthesis of extracellular matrix in orthopaedics or periodontology. This study aimed to determine the concentration of cytokines within platelet-rich fibrin microstructures and investigate whether there are differences in the different portions of platelet-rich fibrin, which has implications for proper clinical use of platelet-rich fibrin gel.

METHODS:

Whole blood was obtained from six New Zealand rabbits (male, 7 to 39 weeks old, weight 2.7-4 kg); it was then centrifuged for preparation of platelet-rich fibrin gels and harvest of plasma. The resultant platelet-rich fibrin gels were used for cytokine determination, histological analyses and scanning electron microscopy. All plasmas obtained were subject to the same cytokine determination assays for the purpose of comparison.

RESULTS:

Cytokines platelet-derived growth factor-BB and transforming growth factor-β1 formed concentration gradients from high at the red blood cell end of the platelet-rich fibrin gel (p=1.88×10-5) to low at the plasma end (p=0.19). Insulin-like growth factor-1 concentrations were similar at the red blood cell and plasma ends. The porosities of the platelet-rich fibrin samples taken in sequence from the red blood cell end to the plasma end were 6.5% ± 4.9%, 24.8% ± 7.5%, 30.3% ± 8.5%, 41.4% ± 12.3%, and 40.3% ± 11.7%, respectively, showing a gradual decrease in the compactness of the platelet-rich fibrin network.

CONCLUSION:

Cytokine concentrations are positively associated with platelet-rich fibrin microstructure and portion in a rabbit model. As platelet-rich fibrin is the main entity currently used in regenerative medicine, assessing cytokine concentration and the most valuable portion of PRF gels is essential and recommended to all physicians.

Autologous blood preparations rich in platelets, fibrin and growth factors

OBJECTIVES

Bone regeneration is often needed prior to dental implant treatment due to the lack of adequate quantity and quality after infectious diseases. The greatest regenerative power was obtained with autologous tissue, primarily the bone alive, taken from the same site or adjacent sites, up to the use centrifugation of blood with the selection of the parts with the greatest potential regenerative. In fact, various techniques and technologies were chronologically successive to cope with an ever better preparation of these concentrates of blood. Our aim is to review these advances and discuss the ways in which platelet concentrates may provide such unexpected beneficial therapeutic effects.

METHODS

The research has been carried out in the MEDLINE and Cochrane Central Register of Controlled Trials database by choosing keywords as "platelet rich plasma", "platelet rich fibrin", "platelet growth factors", and "bone regeneration" and "dentistry".

RESULTS

Autologous platelet rich plasma is a safe and low cost procedure to deliver growth factors for bone and soft tissue healing.

CONCLUSION

The great heterogeneity of clinical outcomes can be explained by the different PRP products with qualitative and quantitative difference among substance.

Vascular endothelial growth factor and biphasic calcium phosphate in the endosseous healing of femoral defects: An experimental rat study

Background/purpose

The presence of adequate bone volume is a critical factor in rehabilitative dentistry. Despite the use of many promising alloplasts, success in stimulating bone formation has been limited, mostly due to poor local biological response. Growth factors have been introduced to stimulate angiogenesis and new bone formation. This histologic and histomorphometric study aimed to evaluate the effect of vascular endothelial growth factor (VEGF) and a biphasic alloplastic graft material (BA) on the healing of endosseous defects in rats.

Materials and methods

Twenty male Wistar rats were used. Two critical-sized bone defects were created in both the right and left femurs of each rat. Each defect was randomly assigned to be treated with VEGF, BA, or VEGF + BA, or to be left empty as a control. Half of the animals were sacrificed after 1 week, and the remaining half were sacrificed after 2 weeks. Inflammation, necrosis, and new bone areas were evaluated by means of histologic and histomorphometric analyses.

Results

Compared to the control group, defects treated with VEGF alone or in combination with BA showed higher rates of bone formation (33.10–46.60%) on Day 7. Additionally, VEGF significantly reduced inflammation and necrosis (P < 0.001). However, the differences were no longer discernable on Day 14.

Conclusion

VEGF makes a significant contribution to angiogenesis and osteogenesis in the early stages of bone defect healing, and its combination with an osteoconductive grafting material (BA) may further enhance new bone formation.

Mandibular Class II Furcation Defect Treatment: Effects of the Addition of Platelet Concentrates to Open Flap: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

BACKGROUND

To improve the efficacy and outcomes of regenerative therapy for furcation defects, the use of platelet concentrates (PCs) in addition to open flap debridement (OFD) has been investigated. The aim of this systematic review is to evaluate whether mandibular Class II furcation defects treated with the addition of PC to OFD heal with a significant improvement in the following: 1) horizontal clinical attachment level (HCAL); 2) vertical clinical attachment level (VCAL); 3) probing depth (PD); and 4) level of gingival margin (LGM).

METHODS

Electronic databases (MEDLINE, EBSCO Library, Cochrane Database of Systematic Reviews, and SCOPUS) were searched for randomized clinical trials to address the use of PCs in combination with OFD compared with a control group without PCs for the treatment of mandibular Class II furcation defects in humans and to provide data on the above reported outcome measures. The results of selected studies were converted to mean difference and standard error and interpolated using the inverse of variance test. Heterogeneity was investigated using both the Higgins index and the Q test.

RESULTS

Of 254 articles screened, only 11 were read in full text, and three of these were included in the meta-analysis. The addition of PCs to OFD revealed a small improvement in the following: 1) HCAL (mean difference, 1.36 mm; 95% confidence interval [CI] = 1.07 to 1.65); 2) VCAL (mean difference, 1.54 mm; 95% CI = 1.23 to 1.85); and 3) PD (mean difference, 1.83 mm; 95% CI = 1.36 to 2.29). No differences were found for the LGM. Heterogeneity across the studies was high, and all the three included studies were performed in one country.

CONCLUSIONS

Adding PCs to OFD for the treatment of mandibular Class II furcation defects may lead to slight improvements in clinical parameters. Nonetheless, because of the high heterogeneity of the very small number of reported studies and the small effect size, no definitive conclusion can be achieved about the clinical application of such a treatment option.

Evaluation of platelet-rich plasma alone or in combination with demineralized freeze dried bone allograft in treatment of periodontal infrabony defects: A comparative clinical trial

Aims:

The use of platelet-rich plasma (PRP) alone in periodontal defects has been controversial and inconclusive. Hence, the present study was designed with the aim to assess the clinical and radiographic effectiveness of PRP alone in infrabony defects.

Materials and Methods:

Thirty infrabony defects were treated with either autologous PRP with open flap debridement (OFD) or autologous PRP + demineralized freeze dried bone graft (DFDBA) with OFD or OFD alone. Clinical parameters recorded were gingival index, plaque index, probing depth (PD), clinical attachment level (CAL), and gingival recession (REC). Radiographic parameters included defect depth reduction, defect resolution, and crestal bone level. All the parameters were recorded at baseline and 12 months postoperatively.

Results:

Mean PD reduction and CAL gain were greater in PRP + DFDBA (4.88 ± 1.12 mm and 4.26 ± 1.85 mm) and PRP (4.86 ± 2.12 mm and 4.10 ± 1.47 mm) groups than the control group (2.69 ± 1.37 mm and 1.27 ± 0.89 mm).

Conclusions:

Within the limits of the study, all the three groups showed significant improvement in clinical parameters from baseline to postoperative 12 months. The amount of defect depth reduction and defect resolution treated with PRP alone group were significantly < PRP + DFDBA. The results pertaining to these parameters were significantly better than the control group.

Periodontal tissue regeneration with PRP incorporated gelatin hydrogel sponges

Gelatin hydrogels have been designed and prepared for the controlled release of the transforming growth factor (TGF-b1) and the platelet-derived growth factor (PDGF-BB). PRP (Platelet rich plasma) contains many growth factors including the PDGF and TGF-b1. The objective of this study was to evaluate the regeneration of periodontal tissue following the controlled release of growth factors in PRP. For the periodontal ligament cells and osteoblast, PRP of different concentrations was added. The assessment of DNA, mitochondrial activity and ALP activity were measured. To evaluate the TGF-β1 release from PRP incorporated gelatin sponge, amounts of TGF-β1 in each supernatant sample were determined by the ELISA. Transplantation experiments to prepare a bone defect in a rat alveolar bone were an implanted gelatin sponge incorporated with different concentration PRP. In DNA assay and MTT assay, after the addition of PRP to the periodontal ligament cells and osteoblast, the cell count and mitochondrial activity had increased the most in the group with the addition of 5  ×  PRP. In the ALP assay, after the addition of PRP to the periodontal ligament cells, the cell activity had increased the most in the group with the addition of 3  ×  PRP. In the transplantation, the size of the bone regenerated in the defect with 3  ×  PRP incorporated gelatin sponge was larger than that of the other group.

Periodontal Specific Differentiation of Dental Follicle Stem Cells into Osteoblast, Fibroblast, and Cementoblast

The dental follicle is a source of dental follicle stem cells (DFCs), which have the potential to differentiate into the periodontal lineage. DFCs therefore are of value in dental tissue engineering. The purpose of this study was to evaluate the effect of growth factor type and concentration on DFC differentiation into periodontal specific lineages. DFCs were isolated from the human dental follicle and characterized for the expression of mesenchymal markers. The cells were positive for CD-73, CD-44, and CD-90; and negative for CD-33, CD-34, and CD-45. The expression of CD-29 and CD-31 was almost negligible. The cells also expressed periodontal ligament and cementum markers such as periodontal ligament-associated protein-1 (PLAP-1), fibroblast growth factor-2 (FGF-2), and cementum protein-1 (CEMP-1), however, the expression of osteoblast markers was absent. Further, the DFCs were cultured in three different induction medium to analyze the osteoblastic, fibroblastic, and cementoblastic differentiation. Runt-related transcription factor 2 (RUNX-2), alkaline phosphatase (ALP) activity, alizarin staining, calcium quantification, collagen type-1 (Col-1), and osteopontin (OPN) expression confirmed the osteoblastic differentiation of DFCs. DFCs cultured in recombinant human FGF-2 (rhFGF-2) containing medium showed enhanced PLAP-1, FGF-2, and COL-1 expression with increasing concentration of rhFGF-2 which thereby confirmed periodontal ligament fibroblastic differentiation. Similarly, DFCs cultured in recombinant human cementum protein-1 (rhCEMP-1) containing medium showed enhanced bone sialoprotein-2 (BSP-2), CEMP-1, and COL-1 expression with respect to rhCEMP-1 which confirmed cementoblastic differentiation. The expression of osteoblast, fibroblast, and cementoblast-related genes of DFCs cultured in induction medium was enhanced in comparison to DFCs cultured in noninduction medium. Thus, growth factor-dependent differentiation of DFCs into periodontal specific lineages was proved by quantitative analysis.

Enamel matrix proteins exhibit growth factor activity: A review of evidence at the cellular and molecular levels

Enamel matrix derivative (EMD) is a commercially available protein extract, mainly comprising amelogenins. A number of other polypeptides have been identified in EMD, mostly growth factors, which promote cementogenesis and osteogenesis during the regeneration processes through the regulation of cell proliferation, differentiation and activity; however, not all of their functions are clear. Enamel extracts have been proposed to have numerous activities such as bone morphogenetic protein- and transforming growth factor β (TGF-β)-like activity, and activities similar to those of insulin-like growth factor, fibroblast growth factor, platelet-derived growth factor, vascular endothelial growth factor and epidermal growth factor. These activities have been observed at the molecular and cellular levels and in numerous animal models. Furthermore, it has been suggested that EMD contains an unidentified biologically active factor that acts in combination with TGF-β1, and several studies have reported functional similarities between growth factors and TGF-β in cellular processes. The effects of enamel extracts on the cell cycle and biology are summarized and discussed in this review.

Evaluation of osteoblastic activity in extraction sockets treated with platelet-rich fibrin

OBJECTIVE

The aim of this study was to determine whether the use of platelet rich fibrin (PRF) improved the healing of extraction sockets.

STUDY DESIGN

A total of 20 patients with bilateral soft tissue impacted mandibular third molars were included in this study. The left and right third molars were extracted during the same session. Subsequently, the PRF membrane was randomly administered to one of the extraction sockets, whereas the contralateral sockets were left without treatment. On postoperative 30. and 90. days, panoramic images and bone scintigrams were taken to evaluate the bone healing between PRF-treated and non-PRF-treated sockets. Also, periodontal evaluation was performed in the same control sessions. Dependent group t test for paired samples was used for statistical analysis.

RESULTS

The average increase in technetium-99m methylene diphosphonate uptake as an indication of enhanced bone healing did not differ significantly between PRF-treated and non-PRF-treated sockets 30 and 90 days postoperatively. Radio-opacity that can show the bone healing on panoramic images were measured by Image J programme and they did not differ significantly. Also periodontal values did not differ significantly.

CONCLUSIONS

PRF might not lead to enhanced bone healing in impacted mandibular third molar extraction sockets 30 and 90 days after surgery. It is thought that PRF has the potential characteristics of an autologous fibrin matrix and can accelerate the healing. To better understand the effects of PRF on healing, further research is warranted with larger sample sizes.

Insulin-like growth factor 1 can promote proliferation and osteogenic differentiation of human dental pulp stem cells via mTOR pathway

Insulin-like growth factor 1 (IGF-1) is a multifunctional peptide that can enhance osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs). However, it remains unclear whether IGF-1 can promote osteogenic differentiation of human dental pulp stem cells (DPSCs). In our study, DPSCs were isolated from the impacted third molars, and treated with IGF-1. Osteogenic differentiation abilities were investigated. We found that IGF-1 activated the mTOR signaling pathway during osteogenic differentiation of DPSCs. IGF-1 also increased the expression of runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), osterix (OSX) and collagen type I (COL I) during this process. Rapamycin, an mTOR inhibitor, blocked osteogenic differentiation induced by IGF-1. Meanwhile, CCK-8 assay and flow cytometry results demonstrated that 10-200 ng/mL IGF-1 could enhance proliferation ability of DPSCs and 100 ng/mL was the optimal concentration. In summary, IGF-1 could promote proliferation and osteogenic differentiation of DPSCs via mTOR pathways, which might have clinical implications for osteoporosis.

Today prospects for tissue engineering therapeutic approach in dentistry

In dental practice there is an increasing need for predictable therapeutic protocols able to regenerate tissues that, due to inflammatory or traumatic events, may suffer from loss of their function. One of the topics arising major interest in the research applied to regenerative medicine is represented by tissue engineering and, in particular, by stem cells. The study of stem cells in dentistry over the years has shown an exponential increase in literature. Adult mesenchymal stem cells have recently been isolated and characterized from tooth-related tissues and they might represent, in the near future, a new gold standard in the regeneration of all oral tissues. The aim of our review is to provide an overview on the topic reporting the current knowledge for each class of dental stem cells and to identify their potential clinical applications as therapeutic tool in various branches of dentistry.

Improvement of bone regeneration capability of ceramic scaffolds by accelerated release of their calcium ions

To regenerate the bone tissue, the fabrication of scaffolds for better tissue regeneration has attracted a great deal of attention. In fact, growth factors are already used in clinical practice and are being investigated for enhancing the capacity for bone tissue regeneration. However, despite their strong osteoinductive activity, these growth factors have several limitations: safety issues, high treatment costs, and the potential for ectopic bone formation. The aim of this study was therefore to develop ceramic scaffolds that could promote the capacity for bone regeneration without growth factors. Three-dimensional ceramic scaffolds were successfully fabricated from hydroxyapatite (HA) and tricalcium phosphate (TCP) using projection-based microstereolithography, which is an additive manufacturing technology. The effects of calcium ions released from ceramic scaffolds on osteogenic differentiation and bone regeneration were evaluated in vitro and in vivo. The osteogenesis-related gene expression and area of new bone formation in the HA/TCP scaffolds was higher than those in the HA scaffolds. Moreover, regenerated bone tissue in HA/TCP scaffolds were more matured than that in HA scaffolds. Through this study, we were able to enhance the bone regeneration capacity of scaffolds not by growth factors but by calcium ions released from the scaffolds. Ceramic scaffolds developed in this study might be useful for enhancing the capacity for regeneration in complex bone defects.

Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre-absorbed with the growth factor. nHA-PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA-PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules.

Human periodontal ligament fibroblast response to rhPDGF-BB application on periodontally diseased root surfaces-in vitro

The aim of the present study was to evaluate the influence of recombinant platelet derived growth factor-BB (rhPDGF-BB) on the cellular proliferation, morphology and adherence of human periodontal ligament fibroblasts (PLFs) to the root surfaces of periodontally diseased and healthy human teeth roots at two different time periods. Primary cell cultures of PLFs were obtained from clinically healthy premolar or mandibular third molar teeth. 11 scaffolds were prepared from healthy teeth for group-1 (Healthy Substrates), 33 scaffolds were prepared from periodontally diseased teeth, which were further divided in Group-2 - Periodontally diseased substrates, Group-3 - Scaled and Root planed (SRP) substrates, Group-4 - SRP + rhPDGF-BB (50 ng/ml). Groups were further subdivided into two groups (n = 5 scaffolds per subgroup) and PLFs were incubated on the scaffolds for three and seven days, topographical assessment was done on the remaining substrate. Cell morphology and counting was assessed under a scanning electron microscope at 350× on day three and seven and statistically compared with the Mann-Whitney U test and the Kruskal-Wallis test. On day three, Group 1 showed least number of cells attached, whereas maximum number of cells were attached on Group 3 (SRP only) substrates. For day 7, Group 1 and Group 4 showed increase in the number of cells from day 3 to 7, while number of cells attached/substrate reduced drastically for Group 2 and 3 substrates. Group 3 and 4 showed better adhesion and proliferation of PLFs as compared to Group 1 and 2. Group-1 and Group-4 showed predominantly spindle cells with flat appearance, Group-3 showed stellate cells and Group-2 showed predominantly distorted spindle shaped cells. The results of this in-vitro study indicates that rhPDGF-BB plays a significant role as an adjunct to periodontal therapy in influencing maturity, attachment and proliferation of PLFs.