Regeneration of periodontal tissues: combinations of barrier membranes and grafting materials - biological foundation and preclinical evidence: A systematic review

Personalized drug-loaded 3D-printed scaffolds for periodontal bone repair: structural, mechanical, and controlled release properties

This study aimed to develop and evaluate personalized 3D-printed scaffolds (SCs) loaded with indomethacin (IND, a model non-steroidal anti-inflammatory drug) for periodontal bone regeneration, using polycaprolactone (PCL), hydroxyapatite (HA), and polyethylene glycol (PEG) as a SC matrix. SCs were fabricated via fused deposition modeling (FDM) 3D printing, following the production of hot melt extruded (HME) filaments (FILs) at varying PEG and IND concentrations. The structural and physicochemical properties were assessed through differential scanning calorimetry (DSC), X-ray diffraction (XRD) and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. Results indicated successful incorporation of PEG and HA within the PCL matrix and complete amorphous dispersion of IND within SCs, with the exception of minimal recrystallization in systems with high IND loading. Mechanical testing of FILs and SCs revealed that the first had the desired properties for FDM-3D printing while the second were suitable for application into the alveolar bone socket. In vitro drug release studies demonstrated a biphasic release profile, with initial rapid release followed by sustained delivery. SCs with higher PEG content exhibited more uniform and faster release than those with lower PEG. Stability tests over three months showed that all SCs maintained IND in its amorphous state, with FDM-printed SCs displaying enhanced stability compared to FILs. The findings of this study suggest that the proposed IND-loaded SCs provide controlled, localized drug release with structural properties tailored for periodontal applications, making them a promising low-cost approach to treat periodontal bone defects.

Biomaterials for Guided Tissue Regeneration and Guided Bone Regeneration: A Review

This review aims to provide an overview of the types of membranes, bone substitutes, and mucosal substitutes used for GTR and GBR and briefly explores recent innovations for tissue regeneration and their future perspectives. Since this is a narrative review, no systematic search, meta-analysis, or statistical analysis was conducted. Using biomaterials for GTR and GBR provides a reduction in postoperative morbidity, as it contributes to less invasive clinical procedures, serving as an alternative to autogenous grafts. Moreover, randomized clinical trials (RCTs) and systematic reviews are essential for the evaluation of new biomaterials. These studies provide more robust evidence and help guide clinical practice in the selection of safer and more effective biomaterials, allowing for the personalization of treatment protocols for each patient.

Customized Hydrogel System for the Spatiotemporal Sequential Treatment of Periodontitis Propelled by ZEB1

Advanced periodontitis initiates with Porphyromonas gingivalis (P. gingivalis) infection, which subsequently triggers chronic inflammation, immune imbalance, and ultimately causes alveolar bone resorption. Traditional periodontal treatment focuses on the elimination of triggering factors, but tend to ignore the improvement of the inflammatory microenvironment and the remodeling of the osteogenic mineralization space. Herein, zinc-aluminum layered double hydroxide nanosheets (LDHs) loaded with icariin (ICA) are encapsulated into a gallic acid (GA)-modified hydroxybutyl chitosan hydrogel (GA-HBC), giving rise to a customized hydrogel system named GA-HBC-LIC, which can sequentially actualize antibacterial, anti-inflammatory, and remineralization functions. A neutral chemical-humoral space is created for osteogenesis via means of sequential regulation by the smart hydrogel. Concomitantly, appropriate mechanical properties and degradation performance of the hydrogel provide a desirable physical space for remineralization. In the spatiotemporal modulation of the hydrogel, zinc finger E-box-binding homeobox 1 (ZEB1) target of released zinc ions (Zn2+) action promotes macrophage polarization from M1 to M2 phenotype, thereby remodeling the immune microenvironment and releasing cytokines conducive to tissue regeneration. In sum, this study highlights the critical role of sequential inflammation regulation and the maintenance of osteogenic space in the regeneration of periodontal tissues, offering new insights for the clinical management of periodontitis.

Chitosan-based dental barrier membrane for periodontal guided tissue regeneration and guided bone regeneration: A review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are two common dental regenerative procedures used to repair periodontal defects caused by periodontitis. In both procedures, a barrier membrane is placed at the interface between the soft tissue and the periodontal defect, serving to impede the infiltration of soft tissue while creating a secluded space for periodontal regeneration. Recently, barrier membranes based on chitosan (CS) have emerged as a promising avenue for these applications. However, despite numerous studies on the development of CS-based membranes, comprehensive review articles specifically addressing their progress in GTR/GBR applications remain scarce. Herein, we review recent research and advancements in the use of CS-based membranes for periodontal GTR and GBR. The review begins by highlighting the advantageous properties of CS that make it a suitable biomaterial for GTR/GBR applications. Next, the development of composite CS-based membranes, reinforced with various compositions like bioactive fillers and therapeutic agents, is discussed in detail based on recent literature, with a focus on their enhanced efficacy in promoting periodontal regeneration. Finally, the review explores the emergence of functionally graded CS-based membranes, emphasizing their potential to address specific challenges encountered in GTR/GBR procedures.

Negative feedback between PTH1R and IGF1 through the Hedgehog pathway in mediating craniofacial bone remodeling

Regeneration of orofacial bone defects caused by inflammation-related diseases or trauma remains an unmet challenge. Parathyroid hormone 1 receptor (PTH1R) signaling is a key mediator of bone remodeling whereas the regulatory mechanisms of PTH1R signaling in oral bone under homeostatic or inflammatory conditions have not been demonstrated by direct genetic evidence. Here, we observed that deletion of PTH1R in Gli1+ progenitors led to increased osteogenesis and osteoclastogenesis. Single-cell and bulk RNA-Seq analysis revealed that PTH1R suppressed the osteogenic potential of Gli1+ progenitors during inflammation. Moreover, we identified upregulated IGF1 expression upon PTH1R deletion. Dual deletion of IGF1 and PTH1R ameliorated the bone-remodeling phenotypes in PTH1R-deficient mice. Furthermore, in vivo evidence revealed an inverse relationship between PTH1R and Hedgehog signaling, which was responsible for the upregulated IGF1 production. Our work underscored the negative feedback between PTH1R and IGF1 in craniofacial bone turnover and revealed mechanisms modulating orofacial bone remodeling.

CALCIUM PHOSPHATE GRAFTS COMBINED WITH GUIDED TISSUE REGENERATION IN THE TREATMENT OF PERIODONTAL BONY DEFECTS- A SYSTEMATIC REVIEW AND META-ANALYSIS

BACKGROUND

The objective of this systematic review is to assess the clinical outcomes of intrabony and furcation defects treated using a regenerative approach with calcium phosphate (CP) grafts combined plus guided tissue regeneration (GTR) membrane in comparison to open flap debridement (OFD).

METHOD

A review protocol was created under PRISMA checklist to find randomized clinical trials (RCTs) in English that compared CPs plus GTR with OFD in humans with intrabony and/or furcation defects. Both electronic and manual searches were conducted. The studied outcomes were probing pocket depth (PD) and clinical attachment level (CAL). To evaluate the treatment effect, a random effects model using restricted maximum likelihood method was performed to estimate the pooled effect size and corresponding 95% confidence interval. The quality assessment of the included studies was performed using Cochrane risk of bias tools version 5.1.0.

RESULTS

Out of the 451 records identified, 7 studies were subjected to meta-analysis after discarding duplicates and excluding the studies that did not meet the inclusion criteria. While treated sites were intrabony defects in 5 papers, 2 studies focused on furcation defects. Based on the findings of the meta-analysis, the weighted mean difference (WMD) of 1.536 mm (95% CI -0.933 to 2.139) and 1.601 mm (95% CI -0.727 to 2.474) was obtained for CAL gain and PD reduction, respectively, in intrabony defects. The differences between CP grafts plus GTR groups and OFD groups for CAL gain and PD reduction were statistically significant. Similarly, for furcation defects, the application of CP grafts with GTR resulted in adjunctive advantages over OFD in terms of CAL gain (WMD of 1.807 mm; 95% CI 0.346-3.268), and PD reduction (WMD of 1.519 mm, 95% CI 1.215-4.253). The analysis on the limited number of study on furcation treatment revealed a statistically significant difference in CAL gain between CP grafts plus GTR groups and OFD groups, but a nonsignificant difference for PD reduction.

CONCLUSION

The results revealed that calcium phosphate grafts combined with GTR are superior to OFD in the healing of periodontal intrabony and furcation defects, considering the limitations of the present systematic review.

Recombinant human fibroblast growth factor and autogenous bone for periodontal regeneration: Alone or in combination? A randomized clinical trial

AIM

To compare the outcomes of therapy using recombinant human fibroblast growth factor (rhFGF)-2 combined with autologous bone grafting (ABG) therapy with those of rhFGF-2 alone and ABG alone in the treatment of periodontal intraosseous defects.

METHODS

Periodontal intraosseous defects were randomized to receive rhFGF-2 therapy + ABG, rhFGF-2 therapy alone, or ABG alone. Periodontal examination and periapical radiography were performed preoperatively and at 3, 6, and 12 months postoperatively.

RESULTS

At the 12 months follow-up, all three groups showed significant improvement in the clinical attachment level (CAL): 5.6 ± 1.6, 5.8 ± 1.7, and 5.2 ± 1.6 mm in the rhFGF-2 + ABG, rhFGF-2 alone, and ABG alone groups, respectively, with no significant inter-group differences (p < .05). rhFGF-2 therapy (alone or in combination) resulted in greater bone defect filling (BDF) (2.3 ± 1.2 mm and 2.6 ± 1.9 mm, respectively) than ABG therapy alone (1.2 ± 1.2 mm). Gingival recession was lesser in the ABG alone (1.2 ± 1.1 mm) and rhFGF-2 + ABG groups (1.4 ± 0.8 mm) than in the rhFGF-2 alone group (2.2 ± 1.2 mm).

CONCLUSION

The results of this study showed that at 12 months postoperatively, all treatments resulted in statistically significant clinical improvements compared to the baseline. From these results, it can be concluded that rhFGF-2 promotes hard tissue regeneration in intraosseous defects.

Janus sponge/electrospun fibre composite combined with EGF/bFGF/CHX promotes reconstruction in oral tissue regeneration

Guided bone regeneration (GBR) is currently the most widely used bone augmentation technique in oral clinics. However, infection and soft tissue management remain the greatest challenge. In this study, a Janus sponge/electrospun fibre membrane containing epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and chlorhexidine (CHX) were prepared to optimize its application as a barrier membrane for GBR. The loose sponge part was covalently bonded with the fiber part which has a dense structure. The composed scaffold exhibited superior biocompatibility and antibacterial activity verified by in vitro test. A rat model of unilateral skull bone injury was used to confirm the effectiveness on both hard and soft tissue regeneration. The chitosan sponge on the soft tissue side containing EGF, bFGF and CHX had a loose structure, promoting collagen and cell regeneration and exerting an antibacterial effect. Meanwhile, the dense PLGA/PCL layer on the hard tissue side prevented fibroblast entry into the bone defect, thereby facilitating bone regeneration. The Janus composite scaffold provides a promising strategy for oral tissue restoration.

Biomimetic Tissue Engineering Strategies for Craniofacial Applications

Biomimetics is the science of imitating nature's designs and processes to create innovative solutions for various fields, including dentistry and craniofacial reconstruction. In these areas, biomimetics involves drawing inspiration from living organisms/systems to develop new materials, techniques, and devices that closely resemble natural tissue structures and enhance functionality. This field has successfully demonstrated its potential to revolutionize craniofacial procedures, significantly improving patient outcomes. In dentistry, biomimetics offers exciting possibilities for the advancement of new dental materials, restorative techniques, and regenerative potential. By analyzing the structure/composition of natural teeth and the surrounding tissues, researchers have developed restorative materials that mimic the properties of teeth, as well as regenerative techniques that might assist in repairing enamel, dentin, pulp, cementum, periodontal ligament, and bone. In craniofacial reconstruction, biomimetics plays a vital role in developing innovative solutions for facial trauma, congenital defects, and various conditions affecting the maxillofacial region. By studying the intricate composition and mechanical properties of the skull and facial bones, clinicians and engineers have been able to replicate natural structures leveraging computer-aided design and manufacturing (CAD/CAM) and 3D printing. This has allowed for the creation of patient-specific scaffolds, implants, and prostheses that accurately fit a patient's anatomy. This review highlights the current evidence on the application of biomimetics in the fields of dentistry and craniofacial reconstruction.

Effects of vitamin K2 administration on guided bone regeneration in diabetic rats

AIM

The present study aimed to investigate the histomorphometric and immunohistochemical impacts of vitamin K2 on guided bone regeneration (GBR) in calvarial critical-size defects (CSDs) in diabetic rats.

METHODS

A total of 30 rats were used in this study, comprising 12 non-diabetic (control) rats and 18 with streptozotocin-nicotinamide-induced experimental Diabetes mellitus (DM). In all rats, two calvarial CSDs were created: one defect was left empty (E), the other was treated with bovine-derived bone graft and collagen-based resorbable membrane (GM). Study groups were as follows: control rats administered saline (n = 6, C-E and C-GM groups) or vitamin K2 (n = 6, CK-E and CK-GM groups) and diabetic rats administered saline (n = 6, DM-E and DM-GM groups) or vitamin K2 (n = 6, DMK-E and DMK-GM groups). After 4 weeks of saline or vitamin K2 administration, the rats were euthanized. Bone defect healing and new bone formation were assessed histomorphometrically, and osteocalcin and osteopontin levels were examined immunohistochemically.

RESULTS

Percentage of new bone formation was greater in CK-GM vs. CK-E and in DMK-GM vs. DMK-E [d = 3.86 (95% CI = 16.38-28.61), d = 1.86, (95% CI = 10.74-38.58), respectively, p < .05]. Bone defect healing scores were higher in CK-GM vs. CK-E and in DMK-GM vs. DMK-E [d = 2.69 (95% CI = -2.12 to -0.87), d = 3.28 (95% CI = 0.98-1.91), respectively, p < .05]. Osteocalcin expression levels were elevated in CK-GM vs. CK-E, in DMK-GM vs. DMK-E [d = 1.19 (95% CI = 0.08-1.41), d = 1.10 (95% CI = 0.02-1.22), respectively p < .05]. Vitamin K2 enhanced osteocalcin expression levels in DMK-E vs. DM-E [d = 2.78, (95% CI = 0.56-1.53), p < .05] and in DMK-GM vs. DM-GM [d = 2.43, (95% CI = 0.65-2.10), p < .05]. Osteopontin expression was enhanced in defects treated with GM vs. E defects [C-GM vs. C-E, d = 1.56 (95% CI = 0.38-2.01); CK-GM vs. CK-E, d = 1.91 (95% CI = 0.49-1.72); DM-GM vs. DM-E, d = 2.34 (95% CI = -1.12 to -0.50); DMK-GM vs. DMK-E, d = 2.00 (95% CI = 0.58-1.91), p < .05].

CONCLUSION

The research findings suggest that administering vitamin K2 in GBR for rats with DM favorably impacts bone healing in CSDs, presenting an adjunctive strategy for bone regeneration.

Treatment of Unfavorable Intrabony Defects with Autogenous Bone Graft in Combination with Leukocyte- and Platelet-Rich Fibrin or Collagen Membranes: A Non-Inferiority Study

Background and Objectives: Unfavorable intrabony defects (IBDs) are associated with the progression of periodontal disease and tooth loss. Growing scientific evidence has demonstrated the effectiveness of platelet concentrations in periodontal treatment. The aim of our study was to demonstrate the non-inferiority of an autogenous bone graft (ABG) associated with leukocyte- and platelet-rich fibrin (L-PRF) compared to ABG + Collagen Membrane in the treatment of IBDs. Material and Methods: Sixty-four patients with at least one IBD were randomly assigned to two groups: ABG+L-PRF and CM+ABG. Clinical and radiographic evaluations were performed at baseline and 12-month follow-up. Clinical attachment level (CAL), gingival recession (GR), probing pocket depth (PPD), and radiograph defect bone level (DBL) were compared between the two treatments. To evaluate the effectiveness of ABG+L-PRF, a non-inferiority margin of =1 mm (-1 mm for GR) was chosen; a second non-inferiority margin of =0.5 mm (-0.5 mm for GR) was set for clinical relevance. Results: At 12-month follow up, both treatments showed clinical and radiographic improvements. The 90% confidence intervals of the CM+ABG-L-PRF+ABG mean difference for CAL gain (-0.0564 mm [-0.316 to 0.203]), DBL gain (-0.433 mm [-0.721 to -0.145]), and PPD reduction (0.232 mm [0.015 to 0.449]) were below the 0.5 mm non-inferiority margin; the GR increase (0.255 mm [0.0645 to 0.445]) stayed above the -0.5 mm. Conclusions: the L-PRF+ABG treatment of unfavorable IBDs is non-inferior with respect to the CM+ABG therapy for CAL gain, but with a lower GR, a slightly higher PPD, and DBL gain.

Effect of Gelatin Content on Degradation Behavior of PLLA/Gelatin Hybrid Membranes

BACKGROUND

Poly(L-lactic acid) (PLLA) is a biodegradable polymer (BP) that replaces conventional petroleum-based polymers.  The hydrophobicity of biodegradable PLLA periodontal barrier membrane in wet state can be solved by alloying it with natural polymers. Alloying PLLA with gelatin imparts wet mechanical properties, hydrophilicity, shrinkage, degradability and biocompatibility to the polymeric matrix.

METHODS

To investigate membrane performance in the wet state, PLLA/gelatin membranes were synthesized by varying the gelatin concentration from 0 to 80 wt%. The membrane was prepared by electrospinning.

RESULTS

At the macroscopic scale, PLLA containing gelatin can tune the wet mechanical properties, hydrophilicity, water uptake capacity (WUC), degradability and biocompatibility of PLLA/gelatin membranes. As the gelatin content increased from 0 to 80 wt%, the dry tensile strength of the membranes increased from 6.4 to 38.9 MPa and the dry strain at break decreased from 1.7 to 0.19. PLLA/gelatin membranes with a gelatin content exceeding 40% showed excellent biocompatibility and hydrophilicity. However, dimensional change (37.5% after 7 days of soaking), poor tensile stress  in wet state (3.48 MPa) and rapid degradation rate (73.7%) were observed. The highest WUC, hydrophilicity, porosity, suitable mechanical properties and biocompatibility were observed for the PLLA/40% gelatin membrane.

CONCLUSION

PLLA/gelatin membranes with gelatin content less than 40% are suitable as barrier membranes for absorbable periodontal tissue regeneration due to their tunable wet mechanical properties, degradability, biocompatibility and lack of dimensional changes.

Insights and Advancements in Periodontal Tissue Engineering and Bone Regeneration

The regeneration of periodontal bone defects continues to be an essential therapeutic concern in dental biomaterials. Numerous biomaterials have been utilized in this sector so far. However, the immune response and vascularity in defect regions may be disregarded when evaluating the effectiveness of biomaterials for bone repair. Among several regenerative treatments, the most recent technique of in situ tissue engineering stands out for its ability to replicate endogenous restorative processes by combining scaffold with particular growth factors. Regenerative medicine solutions that combine biomaterials/scaffolds, cells, and bioactive substances have attracted significant interest, particularly for bone repair and regeneration. Dental stem cells (DSCs) share the same progenitor and immunomodulatory properties as other types of MSCs, and because they are easily isolable, they are regarded as desirable therapeutic agents in regenerative dentistry. Recent research has demonstrated that DSCs sown on newly designed synthetic bio-material scaffolds preserve their proliferative capacity while exhibiting increased differentiation and immuno-suppressive capabilities. As researchers discovered how short peptide sequences modify the adhesion and proliferative capacities of scaffolds by activating or inhibiting conventional osteogenic pathways, the scaffolds became more effective at priming MSCs. In this review, the many components of tissue engineering applied to bone engineering will be examined, and the impact of biomaterials on periodontal regeneration and bone cellular biology/molecular genetics will be addressed and updated.

Gelatin Enhances the Wet Mechanical Properties of Poly(D,L-Lactic Acid) Membranes

Biodegradable (BP) poly(D,L-lactic acid) (PDLLA) membranes are widely used in tissue engineering. Here, we investigate the effects of varying concentrations of PDLLA/gelatin membranes electrospun in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP; C3H2F6O) solvent on their mechanical and physical properties as well as their biocompatibility. Regardless of the environmental conditions, increasing the gelatin content resulted in elevated stress and reduced strain at membrane failure. There was a remarkable difference in strain-to-failure between dry and wet PDLLA/gelatin membranes, with wet strains consistently higher than those of the dry membranes because of the hydrophilic nature of gelatin. A similar wet strain (εw = 2.7-3.0) was observed in PDLLA/gelatin membranes with a gelatin content between 10 and 40%. Both dry and wet stresses increased with increasing gelatin content. The dry stress on PDLLA/gelatin membranes (σd = 6.7-9.7 MPa) consistently exceeded the wet stress (σw = 4.5-8.6 MPa). The water uptake capacity (WUC) improved, increasing from 57% to 624% with the addition of 40% gelatin to PDLLA. PDLLA/gelatin hybrid membranes containing 10 to 20 wt% gelatin exhibited favorable wet mechanical properties (σw = 5.4-6.3 MPa; εw = 2.9-3.0); WUC (337-571%), degradability (11.4-20.2%), and excellent biocompatibility.

Comparison of the clinical efficacy of bone grafting and bone grafting combined with guided tissue regeneration in periodontal regenerative therapy: a meta-analysis

OBJECTIVE

This study aims to compare the clinical efficacy of simple bone grafting and bone grafting combined with guided tissue regeneration (GTR) in periodontal regenerative therapy.

METHODS

The authors systematically searched PubMed, the Web of Science, The National Library of Medicine, the China National Knowledge Infrastructure database and the Wanfang database and collected randomized controlled trials relating to bone graft co-guided tissue regeneration. The retrieval was conducted between January 1990 and December 2022. This study included relevant literature about the clinical efficacy of bone grafting combined with GTR according to the population, intervention, control and outcomes principle and excluded studies using other materials in addition to bone graft and membrane materials. After independently screening the literature, extracting the data and evaluating the risk of bias in the included studies, data analysis was performed using RevMan 5.3 software.  Results: Eighteen studies met the inclusion criteria, and, after further evaluation, a total of 327 teeth that were featured in 15 articles were finally included for meta-analysis. The meta-analysis showed that there was no significant statistical difference in clinical attachment level, probing depth and bone gain between the test group (bone grafting with GTR) and the control group (bone grafting only) at 6 months after the operation (p > 0.05). In terms of gingival recession (GR), the use of non-resorbable membranes produced more recession in the test group compared with the control group (p < 0.05), whereas the use of resorbable membranes produced less recession (p < 0.05).

CONCLUSION

Both simple bone grafting and bone grafting combined with membrane materials have good clinical efficacy in periodontal regenerative therapy, and no significant difference in clinical efficacy is indicated between the two, with the exception of GR.

Preparation and optimization of an eggshell membrane-based biomaterial for GTR applications

OBJECTIVES

Guided Tissue Regeneration (GTR) is a popular clinical procedure for periodontal tissue regeneration. However, its key component, the barrier membrane, is largely collagen-based and is still quite expensive, posing a financial burden to the patients as well as healthcare systems and negatively impacting the patient's decision-making. Thus, our aim is to prepare a novel biomimetic GTR membrane utilizing a natural biomaterial, soluble eggshell membrane protein (SEP), which is economical as it comes from an abundant industrial waste from food and poultry industries, unlike collagen. Additive polymer, poly (lactic-co-glycolic acid) (PLGA), and a bioceramic, nano-hydroxyapatite (HAp), were added to improve its mechanical and biological properties.

METHODS

For this barrier membrane preparation, we initially screened the significant factors affecting its mechanical properties using Taguchi orthogonal array design and further optimized the significant factors using response surface methodology. Furthermore, this membrane was characterized using SEM, EDAX, and ATR-FTIR, and tested for proliferation activity of human periodontal ligament fibroblasts (HPLFs).

RESULTS

Optimization using response surface methodology predicted that the maximal tensile strength of 3.1 MPa and modulus of 39.9 MPa could be obtained at membrane composition of 8.9 wt% PLGA, 7.2 wt% of SEP, and 2 wt% HAp. Optimized PLGA/SEP/HAp membrane specimens that were electrospun on a static collector showed higher proliferation activity of HPLFs compared to tissue culture polystyrene and a commercial collagen membrane.

SIGNIFICANCE

From the results observed, we can conclude that SEP-based nanofibrous GTR membrane could be a promising, environment-friendly, and cost-effective alternative for commercial collagen-based GTR membrane products.

Recent Advances in Scaffolds for Guided Bone Regeneration

The rehabilitation of alveolar bone defects of moderate to severe size is often challenging. Currently, the therapeutic approaches used include, among others, the guided bone regeneration technique combined with various bone grafts. Although these techniques are widely applied, several limitations and complications have been reported such as morbidity, suboptimal graft/membrane resorption rate, low structural integrity, and dimensional stability. Thus, the development of biomimetic scaffolds with tailor-made characteristics that can modulate cell and tissue interaction may be a promising tool. This article presents a critical consideration in scaffold's design and development while also providing information on various fabrication methods of these nanosystems. Their utilization as delivery systems will also be mentioned.

A novel macrolide-Del-1 axis to regenerate bone in old age

Aging is associated with increased susceptibility to chronic inflammatory bone loss disorders, such as periodontitis, in large part due to the impaired regenerative potential of aging tissues. DEL-1 exerts osteogenic activity and promotes bone regeneration. However, DEL-1 expression declines with age. Here we show that systemically administered macrolide antibiotics and a non-antibiotic erythromycin derivative, EM-523, restore DEL-1 expression in 18-month-old ("aged") mice while promoting regeneration of bone lost due to naturally occurring age-related periodontitis. These compounds failed to induce bone regeneration in age-matched DEL-1-deficient mice. Consequently, these drugs promoted DEL-1-dependent functions, including alkaline phosphatase activity and osteogenic gene expression in the periodontal tissue while inhibiting osteoclastogenesis, leading to net bone growth. Macrolide-treated aged mice exhibited increased skeletal bone mass, suggesting that this treatment may be pertinent to systemic bone loss disorders. In conclusion, we identified a macrolide-DEL-1 axis that can regenerate bone lost due to aging-related disease.

Reconstructive Approach in Residual Periodontal Pockets with Biofunctionalized Heterografts-A Retrospective Comparison of 12-Month Data from Three Centers

The regenerative capacity of well-preserved blood clots may be enhanced by biologics like enamel matrix derivative (EMD). This retrospective analysis compares outcomes reported by three centers using different heterografts. Center 1 (C1) treated intrabony defects combining cross-linked high-molecular-weight hyaluronic acid (xHyA) with a xenograft; center 2 (C2) used EMD with an allograft combination to graft a residual pocket. Center 3 (C3) combined xHyA with the placement of a resorbable polymer membrane for defect cover. Clinical parameters, BoP reduction, and radiographically observed defect fill at 12-month examination are reported. The 12-month evaluation yielded significant improvements in PPD and CAL at each center (p < 0.001, respectively). Analyses of Covariance revealed significant improvements in all parameters, and a significantly greater CAL gain was revealed for C2 vs. C1 (p = 0.006). Radiographic defect fill presented significantly higher scores for C2 and C3 vs. C1 (p = 0.003 and = 0.014; C2 vs. C3 p = 1.00). Gingival recession increased in C1 and C3 (p = 1.00), while C2 reported no GR after 12 months (C2:C1 p = 0.002; C2:C3 p = 0.005). BoP tendency and pocket closure rate shared similar rates. Within the limitations of the study, a data comparison indicated that xHyA showed a similar capacity to enhance the regenerative response, as known for EMD. Radiographic follow-up underlined xHyA's unique role in new attachment formation.

Alveolar ridge splitting and simvastatin loaded xenograft for guided bone regeneration and simultaneous implant placement: randomized controlled clinical trial

OBJECTIVES

The present study goal was to assess clinically and radiographically using simvastatin (SMV) loaded xenograft for guided bone regeneration (GBR) around simultaneously placed implants with alveolar ridge splitting in patients with horizontally atrophic jaw defect.

MATERIALS AND METHODS

Randomized distribution of the twenty-two patients into two groups (11 patients each) was performed. Group I participants received alveolar ride splitting (ARS) with GBR using SMV gel mixed bone graft and a barrier membrane with simultaneous implant placement. Group II received the same treatment protocol without SMV gel. At the baseline, 6- and 9-months post-surgery, clinical and radiological alterations were assessed.

RESULTS

Six months after therapy, PES records of group I were statistically significantly improved than those of group II (P < .001). Group I exhibited statistically significant expansion of the alveolar ridge over group II after 6 and 9 months (P < .001). When compared to group II over the evaluation interval between 6 and 9 months, group I demonstrated statistically substantially minimal loss of the mean marginal bone level (P < .001). At the 6- and 9-month observation periods, bone density gain was considerably higher in group I than that in group II (P < .001).

CONCLUSION

Alveolar ridge splitting along with GBR-augmented SMV improve the clinical and radiographical outcomes around dental implant over GBR alone.

CLINICAL RELEVANCE

Augmenting GBR with SMV in alveolar ridge splitting could boost implant osseointegration and enhance peri-implant tissue changes.

CLINICAL TRIAL REGISTRATION

NCT05020405.

Electrospun Poly(L-Lactic Acid)/Gelatin Hybrid Polymer as a Barrier to Periodontal Tissue Regeneration

Poly(L-lactic acid) (PLLA) and PLLA/gelatin polymers were prepared via electrospinning to evaluate the effect of PLLA and gelatin content on the mechanical properties, water uptake capacity (WUC), water contact angle (WCA), degradation rate, cytotoxicity and cell proliferation of membranes. As the PLLA concentration increased from 1 wt% to 3 wt%, the tensile strength increased from 5.8 MPa to 9.1 MPa but decreased to 7.0 MPa with 4 wt% PLLA doping. The WUC decreased rapidly from 594% to 236% as the PLLA content increased from 1 to 4 wt% due to the increased hydrophobicity of PLLA. As the gelatin content was increased to 3 wt% PLLA, the strength, WUC and WCA of the PLLA/gelatin membrane changed from 9.1 ± 0.9 MPa to 13.3 ± 2.3 MPa, from 329% to 1248% and from 127 ± 1.2° to 0°, respectively, with increasing gelatin content from 0 to 40 wt%. However, the failure strain decreased from 3.0 to 0.5. The biodegradability of the PLLA/gelatin blend increased from 3 to 38% as the gelatin content increased to 40 wt%. The viability of L-929 and MG-63 cells in the PLLA/gelatin blend was over 95%, and the excellent cell proliferation and mechanical properties suggested that the tunable PLLA/gelatin barrier membrane was well suited for absorbable periodontal tissue regeneration.

Impact of local drug delivery and natural agents as new target strategies against periodontitis: new challenges for personalized therapeutic approach

Periodontitis is a persistent inflammation of the soft tissue around the teeth that affects 60% of the population in the globe. The self-maintenance of the inflammatory process can cause periodontal damage from the alveolar bone resorption to tooth loss in order to contrast the effects of periodontitis, the main therapy used is scaling and root planing (SRP). At the same time, studying the physiopathology of periodontitis has shown the possibility of using a local drug delivery system as an adjunctive therapy. Using local drug delivery devices in conjunction with SRP therapy for periodontitis is a potential tool since it increases drug efficacy and minimizes negative effects by managing drug release. This review emphasized how the use of local drug delivery agents and natural agents could be promising adjuvants for the treatment of periodontitis patients affected or not by cardiovascular disease, diabetes, and other system problems. Moreover, the review evidences the current issues and new ideas that can inspire potential later study for both basic research and clinical practice for a tailored approach.

Fabrication of hydroxyapatite reinforced polymeric hydrogel membrane for regeneration

Background

The regeneration of lost/damaged support tissue in the periodontium, including the alveolar bone, periodontal ligament, and cementum, is an ambitious purpose of periodontal regenerative therapy and might effectively reduce periodontitis-caused tooth loss. Guided tissue regeneration (GTR) is a technique currently used in dentistry for periodontal surgery, which allows osseous regeneration prior to soft tissue migration into the area of interest. Calcium phosphate-based bone grafts (mostly Tricalcium Phosphate or Hydroxyapatite) are bio ceramics that show the greatest similarity to the mineral found in the bone. Thereby, giving calcium-phosphate excellent biocompatibility, biodegradability and osteoconductivity. The aim of the study is to fabricate hydroxyapatite reinforced polymeric hydrogel membrane for regeneration.

Materials and Method

Pure alginate fabrication was done by cross linking sodium alginate with calcium chloride. Hydroxyapatite (HAP) alginate (Alg) was formulated by adding nanoparticles to the alginate mixture, which was then cross-linked with calcium chloride to formulate a HAP alginate polymeric membrane. The Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscope (SEM), and biocompatibility tests were performed to analyse the membrane characteristics.

Results

Fabricated Hydroxyapatite- alginate (Hap- Alg) membrane has longer durability, because of strong crystal structure which in turn might take a longer time to regenerate. The membrane was found to be biocompatible and HAp induces faster mineralisation which in turn will increase the tissue regeneration rate of the membrane.

Conclusion

The findings of our study suggests that the HAP-Alg hydro gel membrane is highly durable and hemocompatible and it has faster mineralisation capability thus making it superior from the clinically available membranes for GTR. Further analyses needs to be conducted to evaluate the potential of this membrane to be used for regeneration.

Biodegradability of Amniotic Membrane as Potential Scaffold for Periodontal Regeneration

Background In the periodontal regenerative procedure, the membrane used should possess good mechanical stability with suitable resorption time to allow restoration of the lost periodontium. Amniotic membrane (AM) has regenerative potential as a scaffold or barrier membrane due to its various beneficial properties. However, its degradation rate is not clearly reported. Methodology This study aimed to evaluate the resorption capacity of AM and its surface architecture after being subjected to hydrolytic degradation analysis in phosphate buffer solution (PBS). AM was cut into sizes of 10 × 10 mm2 for three replicates. The membranes were weighed before and at different time intervals (days 7, 14, 21, and 28) after immersion in PBS. The degradation rate was determined by the percentage of mean weight loss from the initial weight at different time intervals. The AM surface profile was observed under scanning electron microscopy (SEM) before and after 28 days of immersion. Results The result shows a 92% loss of weight over 28 days with the highest attained in the first seven days (67%), followed by 7%, 17%, and 1% after days 14, 21, and 28, respectively. SEM of the AM surface before the degradation test showed a polygonal shape forming a well-arranged mosaic pattern covered with microvilli. At day 28, the remaining AM appears as porous surface architecture, irregularly arranged fibers, and no microvilli seen. Conclusions This study demonstrated that over four weeks of degradation analysis, AM was not entirely degraded but had lost some of the microstructure. The biodegradability of AM should be further evaluated to elucidate its stability within adequate time parallel with the tissue healing process in periodontal tissue regeneration.

Inhibition of Mertk Signaling Enhances Bone Healing after Tooth Extraction

Regeneration of alveolar bone is an essential step in restoring healthy function following tooth extraction. Growth of new bone in the healing extraction socket can be variable and often unpredictable when systemic comorbidities are present, leading to the need for additional therapeutic targets to accelerate the regenerative process. One such target is the TAM family (Tyro3, Axl, Mertk) of receptor tyrosine kinases. These proteins have been shown to help resolve inflammation and maintain bone homeostasis and thus may have therapeutic benefits in bone regeneration following extraction. Treatment of mice with a pan-TAM inhibitor (RXDX-106) led to accelerated alveolar bone fill following first molar extraction in a mouse model without changing immune infiltrate. Treatment of human alveolar bone mesenchymal stem cells with RXDX-106 upregulated Wnt signaling and primed the cells for osteogenic differentiation. Differentiation of human alveolar bone mesenchymal stem cells with osteogenic media and TAM-targeted inhibitor RXDX-106 (pan-TAM), ASP-2215 (Axl specific), or MRX-2843 (Mertk specific) showed enhanced mineralization with pan-TAM or Mertk-specific inhibitors and no change with Axl-specific inhibitor. First molar extractions in Mertk-/- mice had increased alveolar bone regeneration in the extraction socket relative to wild type controls 7 d postextraction. Flow cytometry of 7-d extraction sockets showed no difference in immune cell numbers between Mertk-/- and wild type mice. RNAseq of day 7 extraction sockets showed increased innate immune-related pathways and genes associated with bone differentiation in Mertk-/- mice. Together, these results indicate that TAM receptor signaling, specifically through Mertk, can be targeted to enhance bone regeneration after injury.

Guided Tissue and Bone Regeneration Membranes: A Review of Biomaterials and Techniques for Periodontal Treatments

This comprehensive review provides an in-depth analysis of the use of biomaterials in the processes of guided tissue and bone regeneration, and their indispensable role in dental therapeutic interventions. These interventions serve the critical function of restoring both structural integrity and functionality to the dentition that has been lost or damaged. The basis for this review is laid through the exploration of various relevant scientific databases such as Scopus, PubMed, Web of science and MEDLINE. From a meticulous selection, relevant literature was chosen. This review commences by examining the different types of membranes used in guided bone regeneration procedures and the spectrum of biomaterials employed in these operations. It then explores the manufacturing technologies for the scaffold, delving into their significant impact on tissue and bone regenerations. At the core of this review is the method of guided bone regeneration, which is a crucial technique for counteracting bone loss induced by tooth extraction or periodontal disease. The discussion advances by underscoring the latest innovations and strategies in the field of tissue regeneration. One key observation is the critical role that membranes play in guided reconstruction; they serve as a barrier, preventing the entry of non-ossifying cells, thereby promoting the successful growth and regeneration of bone and tissue. By reviewing the existing literature on biomaterials, membranes, and scaffold manufacturing technologies, this paper illustrates the vast potential for innovation and growth within the field of dental therapeutic interventions, particularly in guided tissue and bone regeneration.

Preparation of co-electrospinning membrane loaded with simvastatin and substance P to accelerate bone regeneration by promoting cell homing, angiogenesis and osteogenesis

Bone regeneration is a complex process that requires the coordination of various biological events. Developing a tissue regeneration membrane that can regulate this cascade of events is challenging. In this study, we aimed to fabricate a membrane that can enrich the damaged area with mesenchymal stem cells, improve angiogenesis, and continuously induce osteogenesis. Our approach involved creating a hierarchical polycaprolactone/gelatin (PCL/GEL) co-electrospinning membrane that incorporated substance P (SP)-loaded GEL fibers and simvastatin (SIM)-loaded PCL fibers. The membrane could initiate a burst release of SP and a slow/sustained release of SIM for over a month. In vitro experiments, including those related to angiogenesis and osteogenesis (e.g., migration, endothelial network formation, alkaline phosphatase activity, mineralization, and gene expression), clearly demonstrated the membrane's superior ability to improve cell homing, revascularization, and osteogenic differentiation. Furthermore, a series of in vivo studies, including immunofluorescence of CD29⁺/CD90⁺ double-positive cells and immunohistochemical staining for CD34 and vWF, confirmed the co-electrospinning membrane's ability to enhance MSC migration and revascularization response after five days of implantation. After one month, the Micro-CT and histological (Masson and H&E) results showed accelerated bone regeneration. Our findings suggest that a co-electrospinning membrane with time-tunable drug delivery could advance the development of tissue engineering therapeutic strategies and potentially improve patient outcomes.

Calcium Trimetaphosphate-Loaded Electrospun Poly(Ester Urea) Nanofibers for Periodontal Tissue Engineering

The objective of this research was to create and appraise biodegradable polymer-based nanofibers containing distinct concentrations of calcium trimetaphosphate (Ca-TMP) for periodontal tissue engineering. Poly(ester urea) (PEU) (5% w/v) solutions containing Ca-TMP (15%, 30%, 45% w/w) were electrospun into fibrous scaffolds. The fibers were evaluated using SEM, EDS, TGA, FTIR, XRD, and mechanical tests. Degradation rate, swelling ratio, and calcium release were also evaluated. Cell/Ca-TMP and cell/scaffold interaction were assessed using stem cells from human exfoliated deciduous teeth (SHEDs) for cell viability, adhesion, and alkaline phosphatase (ALP) activity. Analysis of variance (ANOVA) and post-hoc tests were used (α = 0.05). The PEU and PEU/Ca-TMP-based membranes presented fiber diameters at 469 nm and 414-672 nm, respectively. Chemical characterization attested to the Ca-TMP incorporation into the fibers. Adding Ca-TMP led to higher degradation stability and lower dimensional variation than the pure PEU fibers; however, similar mechanical characteristics were observed. Minimal calcium was released after 21 days of incubation in a lipase-enriched solution. Ca-TMP extracts enhanced cell viability and ALP activity, although no differences were found between the scaffold groups. Overall, Ca-TMP was effectively incorporated into the PEU fibers without compromising the morphological properties but did not promote significant cell function.

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.

ZnO nanoparticles-modified polycaprolactone-gelatin membranes for guided/bone tissue regeneration, antibacterial and osteogenic differentiation properties

Periodontitis is a highly prevalent infectious disease that causes the progressive destruction of the periodontal supporting tissues. If left untreated, it can lead to tooth loss impairing oral function, aesthetics, and the patient's overall quality of life. Guided and Bone Tissue Regeneration (GTR/BTR) are surgical therapies based on the placement of a membrane that prevents epithelial growth into the defect, allowing the periodontal/bone cells (including stem cells) to regenerate or restore the affected tissues. The success of these therapies is commonly affected by the local bacterial colonization of the membrane area and its fast biodegradation, causing postoperative infections and a premature rupture of the membrane limiting the regeneration process. This study presents the antibacterial and osteogenic differentiation properties of polycaprolactone-gelatin (PCL-G) electrospun membranes modified with ZnO nanoparticles (ZnO-NPs). The membranes´ chemical composition, surface roughness, biodegradation, water wettability, and mechanical properties under simulated physiological conditions, were analyzed by the close relationship with their biological properties. The PCL-G membranes modified with 1, 3, and 6% w/w of ZnO-NPs showed a significant reduction in the planktonic and biofilm formation of four clinically relevant bacteria;A. actinomycetemcomitansserotype b, P. gingivalis,E. coli, andS. epidermidis. Additionally, the membranes presented appropriate mechanical properties and biodegradation rates to be potentially used in clinical treatments. Notably, the membranes modified with the lowest concentration of ZnO-NPs (1% w/w) stimulated the production of osteoblast markers and calcium deposits in human bone marrow-derived mesenchymal stem cells (BM-MSC) and were biocompatible to human osteoblasts cells (hFOB). These results suggest that the PCL-G membranes with 1% w/w of ZnO-NPs are high-potential candidates for GTR/BTR treatments, as they were the most effective in terms of better antibacterial effectiveness at a lower NPs-concentration while creating a favorable cellular microenvironment for bone growth.

3D-Printed Soft Membrane for Periodontal Guided Tissue Regeneration

OBJECTIVES

The current study aimed to perform an in vivo examination using a critical-size periodontal canine model to investigate the capability of a 3D-printed soft membrane for guided tissue regeneration (GTR). This membrane is made of a specific composition of gelatin, elastin, and sodium hyaluronate that was fine-tuned and fully characterized in vitro in our previous study. The value of this composition is its potential to be employed as a suitable replacement for collagen, which is the main component of conventional GTR membranes, to overcome the cost issue with collagen.

METHODS

Critical-size dehiscence defects were surgically created on the buccal surface of the roots of canine bilateral mandibular teeth. GTR treatment was performed with the 3D-printed membrane and two commercially available collagen membranes (Botiss Jason® and Smartbrane-Regedent membranes) and a group without any membrane placement was considered as the control group. The defects were submerged with tension-free closure of the gingival flaps. Histologic and histometric analyses were employed to assess the periodontal healing over an 8-week experimental period.

RESULTS

Histometric evaluations confirmed higher levels of new bone formation in the 3D-printed membrane group. Moreover, in all defects treated with the membranes, the formation of periodontal tissues, bone, periodontal ligaments, and cementum was observed after 8 weeks, while in the control group, only connective tissue was found in the defect sites. There was no clinical sign of inflammation or recession of gingiva in any of the groups.

SIGNIFICANCE

The 3D-printed gelatin/elastin/sodium hyaluronate membrane can be safe and effective for use in GTR for periodontal tissue regeneration therapies, with better or comparable results to the commercial collagen membranes.

The clinical efficacy of periodontally accelerated osteogenic orthodontics in patients with bone fenestration and dehiscence: a retrospective study

PURPOSE

The objective of the study was to explore the effect of periodontally accelerated osteogenic orthodontics (PAOO) in orthodontic patients with bone dehiscence and fenestration in the anterior alveolar region of the mandible.

METHODS

A retrospective study was performed in 42 patients with bone dehiscence and fenestrations in the anterior alveolar region of the mandible who underwent the PAOO technique. The bleeding index (BI), probing depth (PD), keratinized gingiva width (KGW), gingival recession level (GRL), and gingival phenotype were recorded and assessed at baseline and 6 and 12 months postoperatively. Cone-beam computerized tomography was used to measure bone volume in terms of root length (RL), horizontal bone thickness at different levels, and vertical bone height at baseline and 6 months and 12 months after surgery.

RESULTS

The sample was composed of 42 patients (22 males and 20 females; mean age, aged 25.6 ± 4.8 years) with 81 teeth showing dehiscence/fenestrations and 36 sites presenting gingival recessions. There was no significant difference in BI, PD, or KGW (between baseline and 6 or 12 months postoperatively) based on the clinical evaluations (P > 0.05). Gingival recession sites demonstrated a significant reduction in the GRL after surgery (P < 0.05). Furthermore, the proportion of teeth with a thick gingival phenotype increased from 33.61% at baseline to 53.13% at the end of the follow-up. In addition, the bone thickness measurements at the mid-root and crestal levels were markedly increased compared with the baseline values (P < 0.05), although the increase in thickness at the apical level was not statistically significant (P > 0.05).

CONCLUSIONS

Within the limitations of the study, the results show that the PAOO technique is beneficial to periodontal conditions in terms of soft and hard tissue augmentation. The PAOO procedure may represent a safe and efficient treatment for orthodontic patients with bone dehiscence and fenestration.

TRIAL REGISTRATION

This study was approved by the ethics committee of the stomatological hospital affiliated with Xi'an Jiaotong University (xjkqll [2019] No. 016) and registered in the Chinese Clinical Trial Registry (ChiCTR2100053092).

Periodontal Regenerative Therapy Using rhFGF-2 and Deproteinized Bovine Bone Mineral versus rhFGF-2 Alone: 4-Year Extended Follow-Up of a Randomized Controlled Trial

The aim of this study was to evaluate longitudinal outcomes of recombinant human fibroblast growth factor (rhFGF)-2 plus deproteinized bovine bone mineral (DBBM) therapy in comparison with rhFGF-2 alone for treating periodontal intrabony defects. This study describes 4-year follow-up outcomes of the original randomized controlled trial. Intrabony defects in periodontitis patients were treated with rhFGF-2 (control) or rhFGF-2 plus DBBM (test). Clinical, radiographic, and patient-reported outcome (PRO) measures were used to evaluate the outcomes. Thirty-two sites were able to be followed up. At 4 years postoperatively, clinical attachment level (CAL) gains in the test and control groups were 3.5 ± 1.4 mm and 2.7 ± 1.4 mm, respectively, showing significant improvement from preoperative values but no difference between groups. Both groups showed an increase in radiographic bone fill (RBF) over time. At 4 years, the mean value for RBF in the test group (62%) was significantly greater than that in the control group (42%). In 1-2-wall defects, the test treatment yielded significantly greater RBF than the control treatment. No significant difference in PRO scores was noted between the groups. Although no significant difference in CAL gain was found between the groups at the 4-year follow-up, the combination treatment significantly enhanced RBF. Favorable clinical, radiographic outcomes, and PRO in both groups can be maintained for at least 4 years.

Periodontal Therapy Using Bioactive Glasses: A Review

This paper reviews the use of bioactive glasses as materials for periodontal repair. Periodontal disease causes bone loss, resulting in tooth loosening and eventual tooth loss. However, it can be reversed using bioactive glass, typically the original 45S5 formulation (Bioglass®) at the defect site. This is done either by plcing bioactive glass granules or a bioactive glass putty at the defect. This stimulates bone repair and causes the defect to disappear. Another use of bioactive glass in periodontics is to repair so-called furcation defects, i.e., bone loss due to infection at the intersection of the roots in multi-rooted teeth. This treatment also gives good clinical outcomes. Finally, bioactive glass has been used to improve outcomes with metallic implants. This involves either placing bioactive glass granules into the defect prior to inserting the metal implant, or coating the implant with bioactive glass to improve the likelihood of osseointegration. This needs the glass to be formulated so that it does not crack or debond from the metal. This approach has been very successful, and bioactive glass coatings perform better than those made from hydroxyapatite.

Cross-linked hyaluronic acid gel with or without a collagen matrix in the treatment of class III furcation defects: A histologic and histomorphometric study in dogs

AIM

To histologically evaluate the effects of cross-linked hyaluronic acid (xHyA) with or without a collagen matrix (CM) on periodontal wound healing/regeneration in class III furcation defects in dogs.

MATERIALS AND METHODS

Class III furcation defects were surgically created in the mandibular premolars in six beagle dogs. The defects were randomly treated as follows: open flap debridement (OFD) + CM (CM), OFD + xHyA (xHyA), OFD + xHyA + CM (xHyA/CM) and OFD alone (OFD). At 10 weeks, the animals were euthanized for histological evaluation.

RESULTS

The newly formed bone areas in the xHyA (4.04 ± 1.51 mm² ) and xHyA/CM (4.32 ± 1.14 mm² ) groups were larger than those in the OFD (3.25 ± 0.81 mm² ) and CM (3.31 ± 2.26 mm² ) groups. The xHyA (6.25 ± 1.45 mm) and xHyA/CM (6.40 ± 1.35 mm) groups yielded statistically significantly (p < .05) greater formation of new connective tissue attachment (i.e., new cementum, with inserting connective tissue fibres) compared with the OFD (1.47 ± 0.85 mm) group. No significant differences were observed in any of the histomorphometric parameters between the xHyA and xHyA/CM groups. Complete furcation closure was not observed in any of the four treatment modalities.

CONCLUSIONS

Within their limits, the present results suggest that the use of xHyA with or without CM positively influences periodontal wound healing in surgically created, acute-type class III furcation defects.

In Vitro Evaluation of the Permeability of Different Resorbable Xenogeneic Membranes after Collagenolytic Degradation

In this in vitro study, we compare the penetration of cells through different resorbable collagen membranes, which were collagenolytically degraded over different time periods. Three different resorbable collagen membranes were evaluated, including two non-cross-linked (NCL) membranes-namely, a porcine (NCL-P) and an equine (NCL-E) membrane-and an enzymatically cross-linked porcine (ECL-B) membrane. A special two-chamber model was fabricated, allowing for the placement of separating membranes, and a non-porous polyester membrane was used as a negative control (C), in order to verify the impermeability of the experimental chamber device. Round membrane samples with a diameter of 16 mm were fabricated. Eighteen membranes of each type were punched and placed on polyethylene nets as carriers. The membranes were then biodegraded-each on its carrier-in 12-well polystyrene plates: three samples of each membrane type were degraded for 1.5, 3, 6, or 12 h in 2 mL of a buffered collagenase solution, at 37 °C. For control purposes, three samples of each membrane type were not degraded, but only immersed in buffer solution for 1.5, 3, 6, or 12 h, at 37 °C. Another three samples of each type of membrane were degraded until complete dissolution, in order to determine the full hydroxyproline content for comparison. Liquid-preserved boar semen (containing at least 120 million sperm cells per milliliter) was used to test the cell occlusivity of the degraded membranes. At baseline and initial degradation, all tested membranes were tight, and no penetration was observed with up to 30 min of incubation time (results not shown). After 1.5 h, cells were partially capable of penetrating the NCL-E membrane only. One sample showed leakage, with a sperm volume of 1.7 million cells/mL over all samples. No penetration occurred in the test, NCL-P, and ECL-B groups. After a degradation time of 3 h, the NCL-P and ECL-B membranes remained occlusive to cells. All the membranes and measurements indicated leakage in the NCL-E group. After 6 h, four NCL-P measurements showed the first signs of cell penetration, as boar spermatozoa were detectable in the lower chamber (64 million cells/mL). The ECL-B membranes remained completely cell occlusive. After 12 h, four NCL-P measurements were cell penetration positive (14.6 million cells/mL), while the ECL-B group remained tight and showed no cell penetration. As the findings of our study are well in accordance with the results of several previous animal studies, it can be concluded that the surrogate model is capable of performing rapid and cheap screening of cell occlusivity for different collagen membranes in a very standardized manner. In particular, claims of long degradation resistance can be easily proven and compared. As the boar spermatozoa used in the present report had a size of 9 × 5 μm, smaller bacteria are probably also able to penetrate the leaking membranes; in this regard, our proposed study set-up may provide valuable information, although it must be acknowledged that sperm cells show active mobility and do not only translocate by growth.

Parameter Screening and Optimization for a Polycaprolactone-Based GTR/GBR Membrane Using Taguchi Design

Our objective was to determine and optimize the significant parameters affecting mechanical properties and mean fiber diameter (MFD) of a novel GTR/GBR membrane composed of polycaprolactone (PCL) and chicken eggshell membrane (ESM). For this, we prepared electrospun membrane specimens (n = 16) with varying concentrations of PCL, ESM, nano-hydroxyapatite (HAp), and altered electrospinning parameters as generated by DOE++ software. After the determination of MFD and mechanical properties for all specimens, Taguchi orthogonal array L8 design was used to screen significant factors affecting the MFD and mechanical properties. PCL wt%, ESM wt%, HAp wt%, applied voltage (AV), flow rate (FR), and spinneret-collector distance (SCD) were the independent variables investigated. The response variables analyzed were MFD, tensile strength (TS), and elastic modulus. ANOVA outlined ESM wt%, HAp wt%, AV, FR, SCD, and an interactive effect between PCL wt% and AV to be the significant factors affecting modulus values of an electrospun PCL/ESM membrane (p < 0.05). Furthermore, concentrations of PCL and ESM were the significant factors affecting MFD (p < 0.05) and there were no significant factors affecting the TS values. Optimization using DOE++ software predicted that the maximal TS of 3.125 MPa, modulus of 278.168 MPa, and MFD of 882.75 nm could be achieved.

In Vivo Evaluation of Permeable and Impermeable Membranes for Guided Bone Regeneration

Background: The degree of biodegradation and the inflammatory response of membranes employed for guided bone regeneration directly impact the outcome of this technique. This study aimed to evaluate four different experimental versions of Poly (L-lactate-co-Trimethylene Carbonate) (PTMC) + Poly (L-lactate-co-glycolate) (PLGA) membranes, implanted in mouse subcutaneous tissue, compared to a commercially available membrane and a Sham group. Methods: Sixty Balb-C mice were randomly divided into six experimental groups and subdivided into 1, 3, 6 and 12 weeks (n = 5 groups/period). The membranes (1 cm²) were implanted in the subcutaneous back tissue of the animals. The samples were obtained for descriptive and semiquantitative histological evaluation (ISO 10993-6). Results: G1 and G4 allowed tissue adhesion and the permeation of inflammatory cells over time and showed greater phagocytic activity and permeability. G2 and G3 detached from the tissue in one and three weeks; however, in the more extended periods, they presented a rectilinear and homogeneous aspect and were not absorbed. G2 had a major inflammatory reaction. G5 was almost completely absorbed after 12 weeks. Conclusions: The membranes are considered biocompatible. G5 showed a higher degree of biosorption, followed by G1 and G4. G2 and G3 are considered non-absorbable in the studied periods.

Fabrication of oxidized sodium alginate-collagen heterogeneous bilayer barrier membrane with osteogenesis-promoting ability

Guided bone regeneration technique is an effective approach to repair bone defects, in which a barrier membrane is essential. However, the collagen barrier membranes commonly used lose stability quickly, leading to connective tissue invasion and failure of osteogenesis. Herein, we presented an oxidized sodium alginate (OSA)-collagen heterogeneous bilayer barrier membrane with well-controlled pore size and osteogenesis-promoting ability. The OSA crosslinking significantly improved the structural stability, compressive strength, swelling behavior, and slowed down the biodegradation rate of collagen membranes. Meanwhile, the collagen-based membranes exhibited superior cytocompatibility, osteogenesis-promotion, and barrier function against fibroblasts. Especially, the osteogenic differentiation was most promoted on the membrane with a large pore size (240-310 μm), while the barrier function was most improved on the membrane with a small pore size (30-60 μm). Then the above two membranes were combined together to obtain a heterogeneous bilayer membrane. This bilayer barrier membrane showed excellent osteogenesis-promoting ability in rats.

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.

The anti-inflammatory and osteogenic activity of chitosan/polyvinyl alcohol/graphene oxide/astaxanthin nanofibers membranes in vitro study

Anti-inflammation and bone regeneration are the two major goals of periodontal therapy. We have demonstrated that chitosan (CS)/polyvinyl alcohol (PVA)/graphene oxide (GO)/astaxanthin (ASTA) nanofibers membranes prepared by electrospinning had favorable micro-morphology, good mechanical properties, and no cytotoxicity. In this study, CS/PVA/GO/ASTA nanofibers membranes were prepared to modulate both inflammatory response and osteogenic induction in vitro study. When the nanofibers membranes were co-cultured with RAW264.7 cells, glycoprotein nonmetastatic melanoma protein in the cells was highly expressed and RAW264.7 cells were polarized to M2 phenotype at the same time. In addition, following stimulation with nanofibers membranes, the messenger RNA (mRNA) and protein levels of Osteocalcin (OCN) and Runx2 in Bone marrow mesenchymal stem cells (BMSCs) were highly expressed. Taken together, these results suggested CS/PVA/GO/ASTA nanofibers membranes may promote the dissipation of inflammation and stimulate the differentiation of BMSCs into osteoblasts.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

A Hierarchical-Structured Mineralized Nanofiber Scaffold with Osteoimmunomodulatory and Osteoinductive Functions for Enhanced Alveolar Bone Regeneration

Alveolar bone resorption is a major cause of teeth loss and jeopardizes the osseointegration of dental implants, greatly affecting patient's quality of life and health. It is still a great challenge to completely regenerate the alveolar bone defect through traditional guided bone regeneration (GBR) membranes due to their limited bioactivity and regeneration potential. Herein, a new hierarchical-structured mineralized nanofiber (HMF) scaffold, which is combined with both anisotropic and isotropic nanofibrous surface topography and the mineralized particles, is fabricated via a simple template-assisted electrospinning technology and in situ mineralization method. This HMF scaffold can not only directly induce osteogenic differentiation of bone mesenchymal stem cells (osteoinduction), but also stimulate macrophage toward pro-healing (M2) phenotype-polarization with an elevated secretion of the pro-healing cytokines, eventually enhancing the osteogenesis (osteoimmunomodulation). The results of in vivo rat alveolar bone defect repair experiments demonstrate that as compared with the combination of commercial Bio-Gide and Bio-Oss, the single HMF scaffold shows comparable or even superior bone repair effect, with better tissue-integration and more suitable degradation time and accompanied by a simplified operation.

A periodontal tissue regeneration strategy via biphasic release of zeolitic imidazolate framework-8 and FK506 using a uniaxial electrospun Janus nanofiber

Guided tissue regeneration (GTR) strategies are an effective approach to repair periodontal defects by using GTR membranes. However, commercial GTR membranes still have limitations in periodontal tissue regeneration owing to lack of antibacterial and osteogenic properties. The development of novel Janus nanofibers with biphasic release characteristics based on the therapeutic needs of GTR is essential to tackle this issue. Here, we developed a multifunctional Janus nanofiber via uniaxial electrospinning, with zeolitic imidazolate framework-8 nanoparticle (ZIF-8 NP) loading in the hydrophilic polyvinylpyrrolidone (PVP) part and FK506 embedding in the hydrophobic polycaprolactone (PCL) part. The release of Zn²⁺ conformed to the Ritger-Peppas kinetics which could effectively prevent bacterial infection, and the release profile of FK506 was fitted to a first-order equation which could provide persistent osteogenic stimulation for osteogenesis. The periodontal tissue regeneration data from a rat periodontitis model revealed that the multifunctional electrospun Janus nanofibers could be used as an effective bioplatform to restore alveolar bone impairment, compared with the control group. In summary, the Janus nanofibers with biphasic release characteristics quickly exert antibacterial function as well as continuously provide a microenvironment beneficial to the osteogenesis process, demonstrating its great potential for GTR treatment in dental clinic applications.

The Aesthetic Contour Graft - Enhancing peri-implant soft tissue contours and pontic sites with guided bone regeneration

Objective

In this article, we will discuss strategies for enhancing peri‐implant soft tissue contours and pontic sites with hard tissue augmentation.

Clinical consideration

One of the keys to the esthetic illusion of an implant‐supported restoration is to create an ideal emergence profile. A critical part of any emergence profile is based on the height and thickness of the tissue surrounding the restoration and whether there are any defects in this tissue. Even when there is adequate bone in which to place implants, if any irregular ridge anatomy that supports this tissue is not corrected, then an unesthetic appearance of the restoration can result due to the lack of soft tissue with which to develop a proper emergence profile.

Conclusion

Most peri‐implant soft tissue deficiencies represent an underlying bony defect that can be corrected or enhanced through bone augmentation.

Clinical significance

Traditional methods of enhancing soft tissue emergence profiles around implants and pontic sites mostly involve the use of soft tissue augmentation techniques. Although there are few reports of the use of bone augmentation for this purpose, soft tissue contours can be enhanced by augmenting the underlying bone contours and, in many instances, may obviate the need for subsequent soft tissue augmentation.

Effects of baicalin on the proliferation and expression of OPG and RANKL in human cementoblast-lineage cells

Background/purpose

Baicalin, a natural bioactive flavonoid extracted from Scutellaria baicalensis Georgi, mediates bone metabolism, and recent studies have revealed that it has cell signaling properties. However, its biological functions in cementoblasts still remain unclear. This study therefore aimed to investigate the effects of baicalin on bone resorption markers, including osteoprotegerin (OPG) and receptor activator of nuclear factor-κβ ligand (RANKL), in human cementoblast-lineage cells, as well as their proliferation ability.

Materials and methods

Human cementoblast cell line (HCEM) cells were cultured and treated with 0, 0.01, 0.1, or 1 μM of baicalin. The proliferative capacity of cultured HCEM cells was analyzed using bromodeoxyuridine immunoassay and cell counting. The baicalin effect on OPG and RANKL expression was determined using quantitative polymerase chain reaction (qPCR) and western blotting. Furthermore, OPG expression was measured in 1 μM baicalin-treated HCEM cells in the presence or absence of the Wnt signaling pathway inhibitor, Dickkopf (Dkk)-1, using qPCR and western blotting.

Results

The addition of 0.01, 0.1, and 1 μM of baicalin did not significantly change the proliferative capacity of cultured HCEM cells. Compared with the non-supplemented group, baicalin increased and suppressed OPG and RANKL gene and protein expression, respectively, in a concentration-dependent manner. OPG mRNA and protein expression levels were increased by 1 μM baicalin, which was suppressed by Dkk-1 addition.

Conclusion

Baicalin enhanced OPG expression in HCEM cells through the Wnt/beta-catenin signaling pathway, which could contribute to periodontal tissue regeneration.

The added benefit of L-PRF to autogenous bone grafts in the treatment of degree II furcation involvement in mandibular molars

BACKGROUND

Tissue regeneration within the periodontally involved furcation area is one of the most challenging aspects of periodontal surgery. The aim of this study was to evaluate the additional benefit of leukocyte and platelet-rich fibrin (L-PRF) to autogenous bone grafts (ABGs) in the treatment of mandibular molar degree II furcation involvement, comparing the clinical outcomes with those from open flap debridement (OFD)+ABG and OFD alone treatments.

METHODS

Fifty-four patients, exhibiting one buccal or lingual mandibular molar furcation defect, were randomly assigned to three treatment groups: OFD+ABG+L-PRF(n = 18); OFD+ABG (n = 18); and OFD (n = 18). Clinical [probing pocket depth (PPD), horizontal clinical attachment level (HCAL), vertical clinical attachment level (VCAL), gingival recession (GR)] and radiographic [vertical bone level (VBL)] parameters were evaluated at baseline and 6 months after treatment. HCAL change was the primary outcome.

RESULTS

No significant differences within each group were reported for GR changes, but statistically significant improvements in HCAL, VCAL, PPD and VBL were observed in all groups, except for VBL in the OFD group. At 6 months, the mean HCAL gain was 2.29±0.18 mm in the OFD+ABG+L-PRF group, which was significantly greater than that in the OFD+ABG (1.61±0.18 mm) and OFD (0.86±0.18 mm) groups. Both OFD+ABG+L-PRF and OFD+ABG therapies produced a significantly greater clinical and radiographic improvement than OFD.

CONCLUSION

The addition of L-PRF to ABG produces a significantly greater HCAL gain and PPD reduction as compared to OFD+ABG treatment in mandibular degree II furcation involvements. This article is protected by copyright. All rights reserved.

Nanocrystalline hydroxyapatite in regeneration of periodontal intrabony defects: A systematic review and meta-analysis

BACKGROUND

Alveolar bone loss and mobility of teeth is commonly observed in periodontitis patients. Regeneration of periodontal intrabony defects is indicated to restore the lost bone and periodontal tissues. The aim of the present study was to evaluate the clinical outcomes of periodontal intrabony lesions by using nanocrystalline hydroxyapatite (NHA) graft and comparing it with open flap debridement (OFD) alone.

MATERIALS AND METHODS

The eligibility criteria encompassed randomized (RCTs) and controlled clinical trials (CCTs). Weighted mean differences were calculated for clinical attachment level (CAL) gain, probing pocket depth (PPD) reduction and gingival recession (REC) change, demonstrated as forest plots. The revised Cochrane Risk of Bias tool for randomized trials (RoB2) and Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool were used for quality assessment of RCTs and non-randomized trials respectively.

RESULTS

From 22 full-text articles identified, three RCTs, one CCT and one retrospective follow-up of RCT were included. All the five papers comprised the quantitative evaluation. The use of NHA graft provided additional CAL gain of 0.96 mm (p = 0.0009) and PPD reduction of 0.97 mm (p < 0.00001) when compared to OFD alone. However, in terms of REC changes, no considerable benefits of NHA graft were demonstrated than OFD alone (p = 0.48).

CONCLUSIONS

The bioactive NHA graft showed promising results clinically in regenerative periodontology and can be considered for the management of periodontal intrabony defects. The use of NHA graft considerably provided better clinical outcomes in intrabony defects compared to using the OFD alone. Future research investigating NHA graft against other regenerative materials including specific BGs, at longer follow-up periods and bigger sample sizes and in furcation defects warranted.

Porous membranes of quaternized chitosan composited with strontium-based nanobioceramic for periodontal tissue regeneration

This report demonstrates the development of a degradable quaternary ammonium derivative of chitosan (QC) composited with strontium-containing nanoapatite (SA) for bioactivity. The material was made as porous membrane by solution casting and freeze drying, for guided tissue regeneration (GTR) applications. The micromorphology, tensile strength, suture pull-out strength, degradation (in vitro, in phosphate buffered saline), and cytocompatibility (using human periodontal ligament cells) were tested to investigate the effect of derivatization and SA addition. The porosity of the membranes increased with increasing SA content and so did the tensile strength and the degradation. The suture pull-out strength, however, showed a decrease. The cell culture evaluation endorsed biocompatibility. The composite with 1.5 mg SA per 1 mL QC was found to have optimal qualities for GTR applications.