Utilizing collagen membranes for guided tissue regeneration-based root coverage

A multifunctional collagen-base bilayer membrane integrated with a bimetallic/polydopamine network for enhanced guided bone regeneration

The guided bone regeneration (GBR) technique is an effective treatment for small and medium-sized bone defects in the oral and maxillofacial region. However, currently available collagen membranes have limited functionality and are inadequate for clinical requirements. To address this challenge, this study pioneeringly developed a multifunctional bilayer membrane. Specifically, a bimetallic/polydopamine network (BPN), consisting of silver, magnesium, and dopamine, was successfully synthesized for the first time and integrated with collagen and hydroxyapatite. The resulting material was characterized, and its physicochemical properties, along with its barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biosafety effects, were evaluated through both in vitro and in vivo studies. The results indicated that the BPN, composed of magnesium ions, silver nanoparticles (Ag NPs), and polydopamine (PDA), exhibited excellent thermal stability and slow release of silver and magnesium elements. The BPN/Col-HA membrane featured a bilayer structure with uniform distribution of silver and magnesium. It also demonstrated good hydrophilicity, suitable degradation and mechanical properties, as well as sustained release of silver and magnesium. In vitro experiments showed that the BPN/Col-HA membrane possessed desirable barrier, osteogenic, angiogenic, antibacterial, hemostatic, and biocompatible properties. In vivo results further confirmed its biosafety, hemostatic efficacy, and ability to effectively promote bone defect repair and angiogenesis. Thus, the BPN/Col-HA membrane emerges as a multifunctional GBR membrane with potential for clinical translation.

Collagen-based biocomposites inspired by bone hierarchical structures for advanced bone regeneration: ongoing research and perspectives

Bone is a hard-connective tissue composed of matrix, cells and bioactive factors with a hierarchical structure, where the matrix is mainly composed of type I collagen and hydroxyapatite. Collagen fibers assembled by collagen are the template for mineralization and make an important contribution to bone formation and the bone remodeling process. Therefore, collagen has been widely clinically used for bone/cartilage defect regeneration. However, pure collagen implants, such as collagen scaffolds or sponges, have limitations in the bone/cartilage regeneration process due to their poor mechanical properties and osteoinductivity. Different forms of collagen-based composites prepared by incorporating natural/artificial polymers or bioactive inorganic substances are characterized by their interconnected porous structure and promoting cell adhesion, while they improve the mechanical strength, structural stability and osteogenic activities of the collagen matrix. In this review, various forms of collagen-based biocomposites, such as scaffolds, sponges, microspheres/nanoparticles, films and microfibers/nanofibers prepared by natural/synthetic polymers, bioactive ceramics and carbon-based materials compounded with collagen are reviewed. In addition, the application of collagen-based biocomposites as cytokine, cell or drug (genes, proteins, peptides and chemosynthetic) delivery platforms for proangiogenesis and bone/cartilage tissue regeneration is also discussed. Finally, the potential application, research and development direction of collagen-based biocomposites in future bone/cartilage tissue regeneration are discussed.

Evaluation of Guided Bone Regeneration in Critical Defects Using Bovine and Porcine Collagen Membranes: Histomorphometric and Immunohistochemical Analyses

Guided bone regeneration (GBR) is a technique used to facilitate bone regeneration, which uses a biocompatible membrane acting as a physical barrier to prevent the adjacent connective tissue from invading the bone defect. The aim of this study was to evaluate and compare the effectiveness of bovine and porcine collagenous membranes as barriers to connective tissue invasion during the repair of critical bone defects in rat calvaria, using histological, histometric, and immunohistochemical analyses. For this study, 72 rats were divided into three groups: clot group (CG), bovine collagen group (BCG), and porcine collagen group (PCG). Analyses were performed on days 7, 15, 30, and 60. The histological results showed that the PCG exhibited bone neoformation starting from day 7, and after 30 days of repair, the surgical defect was completely filled in some animals. For the BCG, there was little bone neoformation activity in the initial periods, and from day 30 onwards, there was an increase in bone neoformation, with a greater increase on day 60. The data obtained in the histometric analysis reveal that, on day 30, the neoformed bone area did not vary greatly between the PCG and the BCG, though both varied from the CG. By day 60, the PCG presented a greater area of neoformation than the BCG. These results were corroborated by the immunohistochemistry results. In view of the results obtained, it can be concluded that all membranes studied in this research promoted GBR.

Synergetic effect of growth factor and topography on fibroblast proliferation

An innovative basic fibroblast growth factor (bFGF)-loaded polycaprolactone (PCL) fibrous membrane with highly aligned structure is developed for guided tissue regeneration (GTR). The aligned membrane is fabricated by electrospinning. In order to make efficient use of bFGF, PCL electrospun fibrous membrane is firstly surface-coated by self-polymerization of dopamine, and followed by immobilization of heparin via covalent conjugation to the polydopamine (PDA) layer. Subsequently, bFGF is loaded by binding to heparin. The loading yield of bFGF on heparin-immobilized PDA-coated PCL membrane significantly increases to around 7 times as compared with that of pure PCL membrane. NIH-3T3 cells show an enhanced proliferation and exhibit a stretched morphology aligned along the direction of the fibers on the aligned membranes. However, aligned bFGF-loaded PCL membrane exhibit a similar morphology but a highest cell density prolonged till 9 days. The synergetic effect of growth factor and topography would effectively regulate cell proliferation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Biologics-based regenerative technologies for periodontal soft tissue engineering

This manuscript provides a state-of-the-art review on the efficacy of biologics in root coverage procedures, including enamel matrix derivative, platelet-derived growth factor, platelet concentrates, and fibroblast-growth factor-2. The mechanism of action and the rationale for using biologics in periodontal plastic surgery, as well as their anticipated benefits when compared with conventional approaches are discussed. Although the clinical significance is still under investigation, preclinical data and histologic evidence demonstrate that biologic-based techniques are able to promote periodontal regeneration coupled with the provision of tooth root coverage.

Supplemental periodontal regeneration by vertical ridge augmentation around dental implants. A preclinical in vivo experimental study

OBJECTIVES

To evaluate the supplemental periodontal regeneration on adjacent teeth by vertical ridge augmentation around dental implants.

MATERIAL AND METHODS

The second premolar and the fourth premolar were extracted from both sides of the mandible in four beagle dogs. After 2 months, defects of 3 mm and 5 mm deep were formed. In the test group, vertical ridge augmentation was performed around a dental implant, and in the control group, vertical ridge augmentation was performed without implant placement. The animals were euthanized 3 months after the procedure, and radiographic and histomorphometric analyses were performed.

RESULTS

Overall, the test group showed better results than the control group. The presence of new cementum in the histological examination of the test group confirmed that vertical ridge augmentation with proper space maintaining could contribute to periodontal regeneration of adjacent teeth. Statistically significant difference in new bone height (%) was found in group I (5-mm defect depth and implant placement, GBR) when compared with group III (5-mm defect depth, GBR) and IV (3-mm defect depth, GBR). New bone area (%) was statistically different between groups I and IV.

CONCLUSIONS

In conclusion, within the limitation of this study using mandibular residual ridges after extraction of a single tooth in dogs, grafted space was maintained by dental implants better in the deep defect (5-mm depth) than the shallow defect (3-mm depth). Vertical ridge augmentation around dental implants also promoted neighboring periodontal regeneration.

Coronally Advanced Flap with Amniotic Membrane in the Treatment of Gingival Recession: Three Case Reports

Gingival recession is defined as an apical displacement of soft tissues to the cementoenamel junction. Various treatment options for the management of gingival recessions include laterally positioned flap, double papillae flap, coronally advanced flap (CAF) with or without guided tissue regeneration, free gingival autografts, and autogenous subepithelial connective tissue grafts. Three patients with multiple adjacent gingival recessions in the upper jaw were treated utilizing amniotic membrane (Tata memorial) with CAF. The results of this procedure show that amniotic membrane can be used in the treatment of gingival recession defects with significant root coverage and to increase the thickness of keratinized gingiva. There was an increase in height and thickness of keratinized gingiva from 3 to 3.5 mm and 1.5 to 2 mm, respectively. The present results suggest that the combined approach of CAF and amniotic membrane can be considered as a treatment option for multiple adjacent gingival recessions.

Comparison of Attachment and Proliferation of Human Gingival Fibroblasts on Different Collagen Membranes

Background and Aim

Human gingival fibroblasts cultured on collagen membrane as an alternative treatment method used in tissue regeneration can lead to improved results in root coverage. The aim of this study was to evaluate the human gingival fibroblast proliferation and adhesion cultured on three types of collagen membranes.

Materials and Methods

In this in vitro study, first-line human gingival fibroblast cells (HGF1-RT1) prepared and cultured on three membranes, including porcine pericardium (PP) (Jason, Botiss dental), human pericardium (HP) (Regen, Faravardeh Baft Iranian), and glutaraldehyde cross-linked (GC) (BioMend Extend, Zimmer Dental). Cell survival was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) after 24, 48, and 72 h and 7 days. Furthermore, morphology and adhesion of cells on the membrane were evaluated after 1 and 7 days by electron microscopy (scanning electron microscopy [SEM]). Statistical analysis was performed using two-way ANOVA with a significance level of 0.05.

Results

Based on the results of MTT, cell survival on HP and PP membranes after 7 days significantly increased (P < 0.001), but for the GC membrane, it was reduced after 7 days (P = 0.031). Cell survival on HP and PP membranes did not differ (P = 1) and was more than GC (P < 0.001). SEM images showed that the adhesion of cells was better on HP and PP membranes than GC.

Conclusion

The results of this study showed that natural collagen membranes (HP and PP) similarly support proliferation and adhesion of gingival fibroblasts. Survival and adhesion of gingival fibroblasts on cross-linked collagen membrane was less than two other membranes.

Evaluation of efficacy of a novel resorbable collagen membrane for root coverage of Miller's Class I and Class II recession in the maxillary anteriors and premolars

Background:

There are several surgical techniques in literature that have been used to perform root coverage (RC). Currently, the use of a resorbable collagen membrane (RCM) as a guided tissue regenerative material is one of the highly sought treatment modalities. The present study aimed at evaluating the clinical outcome of RC in the treatment of Miller's Class I and II recession defects in maxillary anteriors and premolars by coronally advanced flap (CAF) with and without RCM.

Materials and Methods:

This split-mouth study (bilateral buccal recession defects) was randomized to include 15 test (CAF + membrane) and 15 control (CAF alone) sites. Clinical parameters included gingival recession depth (RD), probing pocket depth (PPD), clinical attachment level (CAL), and keratinized tissue height (KTH) measured at baseline and 9 months postoperatively.

Results:

Both test and control groups showed statistically significant (P < 0.05) reductions in RD (1.54 ± 0.46 mm and 1.60 ± 0.07 mm), PPD (0.53 ± 0.15 mm and 0.94 ± 0.10 mm), increase in KTH (0.67 ± 0.90 mm and 0.73 ± 0.14 mm) and CAL (1.94 ± 0.27 mm and 2.60 ± 0.19 mm) when comparing the 9-month data from baseline. The present study showed that mean improvement in RD was 1.60 ± 0.507 and 1.53 ± 0.64 mm in both test and control groups, respectively. Mean percent RC was 58.33% ±12.19% and 56.22% ±10.22% for test and control groups, respectively. However, there were no statistically significant differences between groups for RD, PPD, KTH, and CAL.

Conclusion:

The results of this study suggest that both the groups CAF (control) and CAF and RCM (test) could be successfully used to treat Miller's Class I and II gingival recession defects and also demonstrated an overall significant improvement in all the assessed clinical parameters. However, there was a greater reduction of gingival RD with the use of RCM when compared with the group of CAF alone.

Regeneration of rabbit calvarial defects using biphasic calcium phosphate and a strontium hydroxyapatite-containing collagen membrane

OBJECTIVES

Biphasic calcium phosphate (BCP) composed of 10% hydroxyapatite (HA) and 90% beta-tricalcium phosphate has been developed. Recently, a strontium hydroxyapatite-containing collagen membrane (Sr) was shown to stimulate early bone formation in rat calvarial defects at 4 weeks postoperatively, as compared with a cross-linked collagen membrane, for guided bone regeneration (GBR). The objective of this study was to evaluate these novel biomaterials for GBR in relation to a non-cross-linked collagen membrane (BG) and deproteinized bovine bone mineral (BO).

MATERIALS AND METHODS

Twenty New Zealand rabbits were used in this study. Four defects of 7 mm in diameter were created in each rabbit, and three of the defects were treated with BG/BO, Sr/BO, and Sr/BCP. Ten rabbits were sacrificed at 12 and 24 weeks, respectively. Histological and histomorphometric analyses were conducted. Volumetric densities of mineralized new bone (MNB), bone marrow (BM), residual grafting material (RG), and non-mineralized connective tissue (NCT) were determined for each group.

RESULTS

After 12 weeks, Sr/BCP yielded more MNB than BG/BO and Sr/BO with no significant difference among the three groups. After 24 weeks, however, Sr/BCP demonstrated significantly more MNB than BG/BO and Sr/BO. Both after 12 and 24 weeks, Sr/BCP showed significantly less RG than BG/BO and Sr/BO. There was a significant increase in MNB in Sr/BCP from 12 to 24 weeks.

CONCLUSIONS

In defects grafted with BCP, more MNB was formed while less RG remained, than in defects grafted with BO. The Sr membrane was as effective as BG when comparing Sr/BO with BG/BO.

Multidisciplinary Treatment of a Fenestration-type Defect

The case report aimed at treating a fenestration-type defect with multidisciplinary conventional and advanced surgical techniques. Fenestrations are isolated areas in which the exposed root surface is covered only by the periosteum and gingiva, but the remaining cortical bone remains intact. Root coverage is indicated in cases of root hypersensitivity, treatment of shallow caries lesions, cervical abrasions, and esthetic and cosmetic needs. In this case report, after proper hygiene instruction and dental biofilm control, a fenestration-type defect was treated using guided tissue regeneration (anorganic bovine matrix and resorbable membrane) and a connective tissue grafts, associated to an endodontic apicoectomy. After reevaluation, the remaining gingival recession was treated with a second gingival connective tissue graft covered with q double papillae type in order to reconstruct the periodontal tissues of the involved tooth. In this clinical case, the interaction between the different areas of dentistry has made it possible to correct a fenestration-type defect, following procedures based on scientific evidence, restoring periodontal health, esthetics, self-esteem, and meeting the patient's expectations regarding her initial complaint. This case report shows the important role of interdisciplinary approach to treating a patient with a complex periodontal defect that required different types of knowledge and abilities to achieve the best results based on the current status of dentistry possibilities.

Critical issues in clinical periodontal research

As periodontal researchers and clinicians, we are challenged every day to make decisions relating to the clinical management of our patients and about how best to conduct clinical periodontal research. This volume of Periodontology 2000 addresses some of the critical issues in contemporary clinical periodontics and periodontal research that are of direct relevance to clinicians, researchers, teachers and students. The 11 review articles in this volume of Periodontology 2000 focus on aspects of periodontal research methodology and clinical periodontology. In terms of research methodology, the articles aim to inform the reader on topics relating to randomized controlled trials in periodontal research, evidence-based dentistry, calibration of clinical examiners and statistics relevant to periodontal research. The clinical periodontology articles address issues relating to decisions on retaining periodontally compromised teeth or replacing them with implants, periodontal management in the patient with osteoporosis, surgical approaches for root coverage and the emerging science of advanced regenerative technologies, including the use of stem cells, for periodontal regeneration. It is hoped that these critical reviews will address many of the dilemmas that confront us on a regular basis and provide practical guidance to those engaged in both clinical periodontology and clinical periodontal research.