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

Evaluation of a hydrogel membrane on bone regeneration in furcation periodontal defects in dogs

The aim of the study was to evaluate bone regeneration using a canine model with surgically created periodontal defects filled for 12 weeks using a stratified biomaterial consisting in a biphasic calcium phosphate (BCP) covered with a crosslinking hydrogel acting as polymer membrane of silated hydroxypropyl methylcellulose (Si-HPMC) as the tested new concept. Bilateral, critical-sized, defects were surgically created at the mandibular premolar teeth of six adult beagle dogs. The defects were randomly allocated and: (i) left empty for spontaneous healing or filled with: (ii) BCP and a collagen membrane; (iii) BCP and hydrogel Si-HPMC membrane. At 12 weeks, the experimental conditions resulted in significantly enhanced bone regeneration in the test BCP/Si-HPMC group. Within the limits of this study, we suggest that the hydrogel Si-HPMC may act as an occlusive barrier to protect bone area from soft connective tissue invasion and then effectively contribute to enhance bone regeneration.

Does Adding Silver Nanoparticles to Leukocyte- and Platelet-Rich Fibrin Improve Its Properties?

Objectives

Leucocyte- and platelet-rich fibrin (L-PRF) membrane can be used in various regenerative treatments. In the case of classical heterologous membrane exposure, microorganisms can be colonized on it and jeopardize the success of treatment. The aim of this study was to compare the antibacterial, mechanical, and histologic characteristics of the L-PRF membrane before and after the addition of silver nanoparticles (SNP).

Materials and Method

This study was performed on 10 volunteer men aged 25-35 years. 20 ml whole bloods were collected from each person and L-PRFs were made by routine and SNP modified method. Mechanical, antibacterial, and histological properties were evaluated.

Results

The antibacterial efficacy of L-PRF and nanosilver-modified L-PRF was presented as Klebsiella pneumonia had growth on the L-PRF membrane after 12 hours. After 24 hours, Klebsiella pneumonia and Streptococcus viridans had growth on L-PRF and only Klebsiella pneumonia had growth on SNP-L-PRF. The tensile strength and stiffness were significantly higher in the SNP-L-PRF. Precipitation of the SNPs was patchy in the outer layers and quite homogeneous in the inner core.

Conclusion

Modification of L-PRF with SNP improves the mechanical properties and antibacterial activity of the L-PRF. It can play an important role in regenerative procedures.

Bone-conditioned medium modulates the osteoconductive properties of collagen membranes in a rat calvaria defect model

OBJECTIVES

Collagen membranes are not limited to be occlusive barriers as they actively support bone regeneration. However, the impact of bone-derived growth factors on their osteoconductive competence has not been examined.

METHODS

Twenty adult Sprague Dawley rats were included in the study. Calvaria defects with a diameter of five millimeter were created. The defect was covered with one layer of a collagen membrane previously soaked in conditioned medium of porcine bone chips or in culture medium alone. After 4 weeks, microcomputed tomography was performed. Undecalcified thin-ground sections were subjected to light and scanning electron microscopy. Primary outcome parameter was the bone volume in the defect. Unit of analysis was the bone-conditioned medium (BCM).

RESULTS

In the central defect area of the control and the BCM group, median new bone connected to the host bone was 0.54 and 0.32 mm³, respectively (p = .10). In the ectocranial defect area, the control group showed significantly more bone than the BCM group (0.90 and 0.26 mm³; p = .02). Based on an exploratory interpretation, the control group had smaller bony islands than the BCM group. Scanning electron microscopy and histology indicate the formation of bone but also the collagen membrane to be mineralized in the defect site.

CONCLUSIONS

These results demonstrate that the commercial collagen membrane holds an osteoconductive competence in a rat calvaria defect model. Soaking collagen membranes with BCM shifts bone formation toward the formation of bony islands rather than new bone connected to the host bone.

Influence of autogenous platelet concentrate on combined GTR/graft therapy in intra-bony defects: A 13-year follow-up of a randomized controlled clinical split-mouth study

AIM

To investigate the clinical long-term outcomes 13 years following guided tissue regeneration (GTR) in deep intra-bony defects with and without additional application of autogenous platelet concentrate (APC).

METHODS

In 25 patients, two deep contra-lateral intra-bony defects were treated according to GTR using β-TCP and bio-resorbable membranes. In test defects, APC was applied additionally. After 13 years, clinical healing results were assessed and compared to results at baseline and after 1 year. Furthermore, a tooth survival analysis was carried out.

RESULTS

After 13 years, 22 patients were available for tooth survival analysis showing 81.8% of test and 86.4% of control teeth still in situ. Based on the 15 patients still available for split-mouth analysis, median CAL was 10.0 mm in test and 12.0 mm in control sites at baseline. After 1 year, both groups revealed significant CAL gains of 5.0 mm, followed by a new CAL loss of 1.0 mm in the following 12 years. There were no significant differences between test and control sites.

CONCLUSION

Within the limits of this study, the data show that most of the CAL gain following GTR can be maintained over 13 years. The additional use of APC had no positive influence on the long-term stability.

Therapeutic effect of bone marrow mesenchymal stem cells pretreated with acetylsalicylic acid on experimental periodontitis in rats

Periodontitis is a local inflammatory environment with dysregulation of host responses, which results in destruction of periodontal tissues. Mesenchymal stem cells (MSCs) have been proven to play important roles in tissue regeneration by serving as progenitor cells, but its therapeutic outcomes are yet, evaluated variable and unpredictable because of the influence of local inflammation. Acetylsalicylic acid (ASA) has been reported to benefit for MSCs in terms of inflammation control and tissue regeneration. In this study, we aimed to explore the effect of bone marrow mesenchymal stem cells (BMMSCs) pretreated with ASA (ASA-BMMSCs) on periodontal bone repair in a ligature and bacteria-induced periodontitis model in rats. We show herein that, ASA-BMMSCs treatment reduced inflammatory infiltration and alveolar bone loss in periodontitis rats, reflected by immunohistochemistry staining of OPG/RANK-L and Micro-CT. Levels of TNF-α and IL-17 decreased while IL-10 increased after the treatment of ASA-BMMSCs in periodontitis rats. In addition, less osteoclasts number was detected in ASA-BMMSCs treated group. In vitro study showed that ASA facilitated BMMSCs proliferation and differentiation, which might explain the reduced bone loss in periodontitis. These results together suggest that local application of ASA-BMMSCs in periodontal lesion sites is capable of improving inflammatory microenvironment, promoting alveolar bone regeneration, thus leading to a recovery of periodontal homeostasis. Besides, this study also provides us a new idea that a combined application of ASA and BMMSCs may be a novel approach for periodontitis treatment and periodontal bone regeneration.

Bioprinting-Based PDLSC-ECM Screening for in Vivo Repair of Alveolar Bone Defect Using Cell-Laden, Injectable and Photocrosslinkable Hydrogels

Periodontitis is an inflammatory disease worldwide that may result in periodontal defect (especially alveolar bone defect) and even tooth loss. Stem-cell-based approach combined with injectable hydrogels has been proposed as a promising strategy in periodontal treatments. Stem cells fate closely depends on their extracellular matrix (ECM) characteristics. Hence, it is necessary to engineer an appropriate injectable hydrogel to deliver stem cells into the defect while serving as the ECM during healing. Therefore, stem cell-ECM interaction should be studied for better stem cell transplantation. In this study, we developed a bioprinting-based strategy to study stem cell-ECM interaction and thus screen an appropriate ECM for in vivo repair of alveolar bone defect. Periodontal ligament stem cells (PDLSCs) were encapsulated in injectable, photocrosslinkable composite hydrogels composed of gelatin methacrylate (GelMA) and poly(ethylene glycol) dimethacrylate (PEGDA). PDLSC-laden GelMA/PEGDA hydrogels with varying composition were efficiently fabricated via a 3D bioprinting platform by controlling the volume ratio of GelMA-to-PEGDA. PDLSC behavior and fate were found to be closely related to the engineered ECM composition. The 4/1 GelMA/PEGDA composite hydrogel was selected since the best performance in osteogenic differentiation in vitro. Finally, in vivo study indicated a maximal and robust new bone formation in the defects treated with the PDLSC-laden hydrogel with optimized composition as compared to the hydrogel alone and the saline ones. The developed approach would be useful for studying cell-ECM interaction in 3D and paving the way for regeneration of functional tissue.

Biological evaluation of silver nanoparticles incorporated into chitosan-based membranes

AIM

To evaluate the antibacterial potential and biological performance of silver nanoparticles in chitosan-based membranes.

MATERIALS & METHODS

Electrospun chitosan/poly(ethylene oxide) membranes with different amounts of silver nanoparticles were evaluated for antibacterial properties and cytotoxicity in vitro and for tissue response in a rabbit subcutaneous model.

RESULTS

The nanoparticles displayed dose-dependent antibacterial properties against Porphyromonas gingivalis and Fusobacterium nucleatum, without showing noticeable cytotoxicity. The membranes with silver nanoparticles evoked a similar inflammatory response compared with the membranes without silver nanoparticles.

CONCLUSION

The antibacterial effect, combined with the findings on cyto- and biocompatibility warrants further investigation to the usefulness of chitosan/poly(ethylene oxide) membranes with silver nanoparticles, for clinical applications like guided tissue regeneration.

Advanced Scaffolds for Dental Pulp and Periodontal Regeneration

No current therapy promotes root canal disinfection and regeneration of the pulp-dentin complex in cases of pulp necrosis. Antibiotic pastes used to eradicate canal infection negatively affect stem cell survival. Three-dimensional easy-to-fit antibiotic-eluting nanofibers, combined with injectable scaffolds, enriched or not with stem cells and/or growth factors, may increase the likelihood of achieving predictable dental pulp regeneration. Periodontitis is an aggressive disease that impairs the integrity of tooth-supporting structures and may lead to tooth loss. The latest advances in membrane biomodification to endow needed functionalities and technologies to engineer patient-specific membranes/constructs to amplify periodontal regeneration are presented.

A collagen membrane containing osteogenic protein-1 facilitates bone regeneration in a rat mandibular bone defect

OBJECTIVES

Osteogenic protein-1 (OP-1) has shown osteoinductive activities and is useful for clinical treatments, including bone regeneration. Regenerative procedures using a bioabsorbable collagen membrane (BCM) are well established in periodontal and implant dentistry. We evaluated the subsequent effects of the BCM in combination with OP-1 on bone regeneration in a rat mandibular circular critical-sized bone defect in vivo.

DESIGN

We used 8 rats that received surgery in both sides of the mandible, and created the total 16 defects which were divided into 4 groups: Group 1; no treatment, as a control, Group 2; BCM alone, Group 3; BCM containing low dose 0.5μg of OP-1 (L-OP-1), and Group 4; BCM containing high dose 2.0μg of OP-1 (H-OP-1). Newly formed bone was evaluated by micro computed tomography (micro-CT) and histological analyses at 8 weeks postoperatively. In quantitative and qualitative micro-CT analyses of the volume of new bone formation, bone density, and percentage of new bone area was evaluated.

RESULTS

BCM with rhOP-1 significantly increased and accelerated bone volume, bone mineral density, and percentage of new bone area compared to control and BCM alone at 8 weeks after surgery; these enhancements in bone regeneration in the OP-1-treated groups were dose-dependent.

CONCLUSIONS

OP-1 delivered with a BCM may have effective osteoinductive potency and be a good combination for bone regeneration. The use of such a combination device for osteogenesis may result in safer and more predictable bone regenerative outcomes in the future.

The Mechanical Properties and Biometrical Effect of 3D Preformed Titanium Membrane for Guided Bone Regeneration on Alveolar Bone Defect

The purpose of this study is to evaluate the effect of three-dimensional preformed titanium membrane (3D-PFTM) to enhance mechanical properties and ability of bone regeneration on the peri-implant bone defect. 3D-PFTMs by new mechanically compressive molding technology and manually shaped- (MS-) PFTMs by hand manipulation were applied in artificial peri-implant bone defect model for static compressive load test and cyclic fatigue load test. In 12 implants installed in the mandibular of three beagle dogs, six 3D-PFTMs, and six collagen membranes (CM) randomly were applied to 2.5 mm peri-implant buccal bone defect with particulate bone graft materials for guided bone regeneration (GBR). The 3D-PFTM group showed about 7.4 times higher mechanical stiffness and 5 times higher fatigue resistance than the MS-PFTM group. The levels of the new bone area (NBA, %), the bone-to-implant contact (BIC, %), distance from the new bone to the old bone (NB-OB, %), and distance from the osseointegration to the old bone (OI-OB, %) were significantly higher in the 3D-PFTM group than the CM group (p < .001). It was verified that the 3D-PFTM increased mechanical properties which were effective in supporting the space maintenance ability and stabilizing the particulate bone grafts, which led to highly efficient bone regeneration.

Sandwich-type PLLA-nanosheets loaded with BMP-2 induce bone regeneration in critical-sized mouse calvarial defects

To overcome serious clinical problems caused by large bone defects, various approaches to bone regeneration have been researched, including tissue engineering, biomaterials, stem cells and drug screening. Previously, we developed a free-standing biodegradable polymer nanosheet composed of poly(L-lactic acid) (PLLA) using a simple fabrication process consisting of spin-coating and peeling techniques. Here, we loaded recombinant human bone morphogenetic protein-2 (rhBMP-2) between two 60-nm-thick PLLA nanosheets, and investigated these sandwich-type nanosheets in bone regeneration applications. The PLLA nanosheets displayed constant and sustained release of the loaded rhBMP-2 for over 2months in vitro. Moreover, we implanted the sandwich-type nanosheets with or without rhBMP-2 into critical-sized defects in mouse calvariae. Bone regeneration was evident 4weeks after implantation, and the size and robustness of the regenerated bone had increased by 8weeks after implantation in mice implanted with the rhBMP-2-loaded nanosheets, whereas no significant bone formation occurred over a period of 20weeks in mice implanted with blank nanosheets. The PLLA nanosheets loaded with rhBMP-2 may be useful in bone regenerative medicine; furthermore, the sandwich-type PLLA nanosheet structure may potentially be applied as a potent prolonged sustained-release carrier of other molecules or drugs.

STATEMENTS OF SIGNIFICANCE

Here we describe sandwich-type poly(L-lactic acid) (PLLA) nanosheets loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) as a novel method for bone regeneration. Biodegradable 60-nm-thick PLLA nanosheets display strong adhesion without any adhesive agent. The sandwich-type PLLA nanosheets displayed constant and sustained release of the loaded rhBMP-2 for over 2months in vitro. The nanosheets with rhBMP-2 markedly enhanced bone regeneration when they were implanted into critical-sized defects in mouse calvariae. In addition to their application for bone regeneration, PLLA nanosheets may be useful for various purposes in combination with various drugs or molecules, because they displays excellent capacity as a sustained-release carrier.

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

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

Poly(Lactic-co-Glycolic Acid): Applications and Future Prospects for Periodontal Tissue Regeneration

Periodontal tissue regeneration is the ultimate goal of the treatment for periodontitis-affected teeth. The success of regenerative modalities relies heavily on the utilization of appropriate biomaterials with specific properties. Poly (lactic-co-glycolic acid) (PLGA), a synthetic aliphatic polyester, has been actively investigated for periodontal therapy due to its favorable mechanical properties, tunable degradation rates, and high biocompatibility. Despite the attractive characteristics, certain constraints associated with PLGA, in terms of its hydrophobicity and limited bioactivity, have led to the introduction of modification strategies that aimed to improve the biological performance of the polymer. Here, we summarize the features of the polymer and update views on progress of its applications as barrier membranes, bone grafts, and drug delivery carriers, which indicate that PLGA can be a good candidate material in the field of periodontal regenerative medicine.

Pro-resolving mediators in the regulation of periodontal disease

Periodontitis is an inflammatory disease of the supporting structures of the dentition that is initiated by bacteria that form a biofilm on the surface of the teeth. The pathogenesis of the disease is a result of complex interactions between the biofilm and the host response that results in dysbiosis of the microbiome and dysregulation of the inflammatory response. Current data suggest that the excess inflammation associated with periodontitis is due to a failure of resolution of inflammation pathways. In this review, the relationship between inflammation and microbial dysbiosis is examined in the context of pro-inflammation and pro-resolution mediators and their ability to modify the course of disease. The impact of local oral inflammation on systemic inflammation and the relationship of periodontitis to other inflammatory diseases, including type 2 diabetes and cardiovascular disease is reviewed. Active resolvers of inflammation, including the lipoxins and resolvins, show great promise as therapeutics for the treatment of periodontitis and other inflammatory diseases.

Efficacy of stem cells on periodontal regeneration: Systematic review of pre-clinical studies

This systematic review aims to evaluate mesenchymal stem cells (MSC) periodontal regenerative potential in animal models. MEDLINE, EMBASE and LILACS databases were searched for quantitative pre-clinical controlled animal model studies that evaluated the effect of local administration of MSC on periodontal regeneration. The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Twenty-two studies met the inclusion criteria. Periodontal defects were surgically created in all studies. In seven studies, periodontal inflammation was experimentally induced following surgical defect creation. Differences in defect morphology were identified among the studies. Autogenous, alogenous and xenogenous MSC were used to promote periodontal regeneration. These included bone marrow-derived MSC, periodontal ligament (PDL)-derived MSC, dental pulp-derived MSC, gingival margin-derived MSC, foreskin-derived induced pluripotent stem cells, adipose tissue-derived MSC, cementum-derived MSC, periapical follicular MSC and alveolar periosteal cells. Meta-analysis was not possible due to heterogeneities in study designs. In most of the studies, local MSC implantation was not associated with adverse effects. The use of bone marrow-derived MSC for periodontal regeneration yielded conflicting results. In contrast, PDL-MSC consistently promoted increased PDL and cementum regeneration. Finally, the adjunct use of MSC improved the regenerative outcomes of periodontal defects treated with membranes or bone substitutes. Despite the quality level of the existing evidence, the current data indicate that the use of MSC may provide beneficial effects on periodontal regeneration. The various degrees of success of MSC in periodontal regeneration are likely to be related to the use of heterogeneous cells. Thus, future studies need to identify phenotypic profiles of highly regenerative MSC populations.

The Effect of Thickness of Resorbable Bacterial Cellulose Membrane on Guided Bone Regeneration

This study introduces the effect of the thickness of a bacterial cellulose membrane by comparing the bone regeneration effect on rat skulls when using a collagen membrane and different thicknesses of resorbable bacterial cellulose membranes for guided bone regeneration. Barrier membranes of 0.10 mm, 0.15 mm, and 0.20 mm in thickness were made using bacterial cellulose produced as microbial fermentation metabolites. Mechanical strength was investigated, and new bone formation was evaluated through animal experimental studies. Experimental animals were sacrificed after having 2 weeks and 8 weeks of recovery, and specimens were processed for histologic and histomorphometric analyses measuring the area of bone regeneration (%) using an image analysis program. In 2 weeks, bone-like materials and fibrous connective tissues were observed in histologic analysis. In 8 weeks, all experimental groups showed the arrangement of osteoblasts surrounding the supporting body on the margin and center of the bone defect region. However, the amount of new bone formation was significantly higher (p < 0.05) in bacterial cellulose membrane with 0.10 mm in thickness compared to the other experimental groups. Within the limitations of this study, a bacterial cellulose membrane with 0.10 mm thickness induced the most effective bone regeneration.

Comparison of Different Periodontal Healing of Critical Size Noncontained and Contained Intrabony Defects in Beagles

BACKGROUND

Regenerative techniques help promote the formation of new attachment and bone filling in periodontal defects. However, the dimensions of intraosseous defects are a key determinant of periodontal regeneration outcomes. In this study, we evaluated the efficacy of use of anorganic bovine bone (ABB) graft in combination with collagen membrane (CM), to facilitate healing of noncontained (1-wall) and contained (3-wall) critical size periodontal defects.

METHODS

The study began on March 2013, and was completed on May 2014. One-wall (7 mm × 4 mm) and 3-wall (5 mm × 4 mm) intrabony periodontal defects were surgically created bilaterally in the mandibular third premolars and first molars in eight beagles. The defects were treated with ABB in combination with CM (ABB + CM group) or open flap debridement (OFD group). The animals were euthanized at 8-week postsurgery for histological analysis. Two independent Student's t-tests (1-wall [ABB + CM] vs. 1-wall [OFD] and 3-wall [ABB + CM] vs. 3-wall [OFD]) were used to assess between-group differences.

RESULTS

The mean new bone height in both 1- and 3-wall intrabony defects in the ABB + CM group was significantly greater than that in the OFD group (1-wall: 4.99 ± 0.70 mm vs. 3.01 ± 0.37 mm, P < 0.05; 3-wall: 3.11 ± 0.59 mm vs. 2.08 ± 0.24 mm, P < 0.05). The mean new cementum in 1-wall intrabony defects in the ABB + CM group was significantly greater than that in their counterparts in the OFD group (5.08 ± 0.68 mm vs. 1.16 ± 0.38 mm; P < 0.05). Likewise, only the 1-wall intrabony defect model showed a significant difference with respect to junctional epithelium between ABB + CM and OFD groups (0.67 ± 0.23 mm vs. 1.12 ± 0.28 mm, P < 0.05).

CONCLUSIONS

One-wall intrabony defects treated with ABB and CM did not show less periodontal regeneration than that in 3-wall intrabony defect. The noncontained 1-wall intrabony defect might be a more discriminative defect model for further research into periodontal regeneration.

Treatment of a Developmental Groove and Supernumerary Root Using Guided Tissue Regeneration Technique

Introduction. The radicular groove is a developmental groove which is usually found on the palatal or lateral aspects of the maxillary incisor teeth. The present case is a maxillary lateral incisor with a small second root and a deep radicular groove. The developmental groove caused a combined periodontal-endodontic lesion. Methods. Case was managed using a combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal treatment. After completion of root canal treatment, guided tissue regeneration (GTR) was carried out using decalcified freeze dried bone allograft (DFDBA) and a bioabsorbable collagenous membrane. Tooth also was splinted for two months. Results. After 12 months the tooth was asymptomatic. The periapical radiolucency disappeared and probing depth did not exceed 3 mm. Conclusion. Combined treatment procedure involving nonsurgical root canal therapy and surgical periodontal regenerative treatment can be a predictable technique in treating combined endodontic-periodontal lesions caused by radicular groove.

Effectiveness of bovine-derived xenograft versus bioactive glass with periodontally accelerated osteogenic orthodontics in adults: a randomized, controlled clinical trial

Background

Periodontally accelerated osteogenic orthodontics (PAOO) combines periodontal therapy with orthodontic therapy, which minimises treatment time. This study compared the effectiveness of a bovine-derived xenograft with that of bioactive glass when combined with PAOO for the treatment of adult patients with moderate crowding of the teeth.

Methods

In this prospective, single-masked clinical trial, 33 orthodontic patients (20 women, 13 men; mean age 21.2 ± 1.43 [18 − 27] years), were randomly allocated to one of three groups. Group 1 underwent a modified corticotomy technique on the labial side only, whereas group 2 was treated with the same technique combined with PAOO using a bovine-derived xenograft and group 3 was treated in the same way but combining PAOO with bioactive glass. The total treatment duration was recorded from the start of active orthodontic treatment, immediately after corticotomy, and at the time of debonding. Probing depth was evaluated clinically and bone density and root length were evaluated radiographically on the day of surgery (baseline, T1), post-treatment at debonding (T2), and 9 months post-treatment (T3).

Results

The duration of orthodontic treatment was markedly reduced to an average of 11.4 ± 0.14 weeks in all groups. All probing depths were < 3 mm, the interdental papillae were well preserved, there was no loss of tooth vitality, and there was no evidence of significant apical root resorption at any time interval. All groups showed a decrease in mean bone density at T2 followed by an increase at T3. The net percentage change that occurred between baseline and 9 months post-treatment was significantly different between the three groups. Groups 2 and 3, where grafts were incorporated, demonstrated a statistically significant greater increase in bone density than group 1 at T3.

Conclusion

Combination of orthodontic treatment and periodontal surgery is an effective treatment for adult patients that decreases the duration of active treatment and reduces the risk of root resorption. Use of a bovine-derived xenograft with modified corticotomy provided superior benefits in terms of increased bone density than did the use of bioactive glass.

Trial registration

The study was retrospectively registered at ClinicalTrials.gov under Clinical Trial Registration Number: NCT02796911.

The influence of root surface distance to alveolar bone and periodontal ligament on periodontal wound healing

PURPOSE

The purpose of this animal study was to perform a 3-dimensional micro-computed tomography (micro-CT) analysis in order to investigate the influence of root surface distance to the alveolar bone and the periodontal ligament on periodontal wound healing after a guided tissue regeneration (GTR) procedure.

METHODS

Three adult Sus scrofa domesticus specimens were used. The study sample included 6 teeth, corresponding to 2 third mandibular incisors from each animal. After coronectomy, a circumferential bone defect was created in each tooth by means of calibrated piezoelectric inserts. The experimental defects had depths of 3 mm, 5 mm, 7 mm, 9 mm, and 11 mm, with a constant width of 2 mm. One tooth with no defect was used as a control. The defects were covered with a bioresorbable membrane and protected with a flap. After 6 months, the animals were euthanised and tissue blocks were harvested and preserved for micro-CT analysis.

RESULTS

New alveolar bone was consistently present in all experimental defects. Signs of root resorption were observed in all samples, with the extent of resorption directly correlated to the vertical extent of the defect; the medial third of the root was the most commonly affected area. Signs of ankylosis were recorded in the defects that were 3 mm and 7 mm in depth. Density and other indicators of bone quality decreased with increasing defect depth.

CONCLUSIONS

After a GTR procedure, the periodontal ligament and the alveolar bone appeared to compete in periodontal wound healing. Moreover, the observed decrease in bone quality indicators suggests that intrabony defects beyond a critical size cannot be regenerated. This finding may be relevant for the clinical application of periodontal regeneration, since it implies that GTR has a dimensional limit.

Periodontal regeneration in swine after cell injection and cell sheet transplantation of human dental pulp stem cells following good manufacturing practice

Background

Periodontitis, one of the most prevalent infectious diseases in humans, results in the destruction of tooth-supporting tissues. The purpose of the present study is to evaluate the effect of cell injection and cell sheet transplantation on periodontal regeneration in a swine model.

Methods

In the present study, human dental pulp stem cells (hDPSCs) were transplanted into a swine model for periodontal regeneration. Twelve miniature pigs were used to generate periodontitis with bone defects of 5 mm in width, 7 mm in length, and 3 mm in depth. hDPSCs were obtained for bone regeneration using cell injection or cell sheet transplantation. After 12 weeks, clinical, radiological, and histological assessments of regenerated periodontal tissues were performed to compare periodontal regeneration treated with xenogeneic cell injection and cell sheet implantation.

Results

Our study showed that translating hDPSCs into this large animal model could significantly improve periodontal bone regeneration and soft tissue healing. After 12 weeks, both the hDPSC sheet treatment and hDPSC injection significantly improved periodontal tissue healing clinically in comparison with the control group. The volume of regenerative bone in the hDPSC sheet group (52.7 ± 4.1 mm³) was significantly larger than in the hDPSC injection group (32.4 ± 5.1 mm³) (P < 0.05). The percentage of bone in the periodontium in the hDPSC injection group was 12.8 ± 4.4 %, while it was 17.4 ± 5.3 % in the hDPSC sheet group (P < 0.05).

Conclusion

Both hDPSC injection and cell sheet transplantation significantly regenerated periodontal bone in swine. The hDPSC sheet had more bone regeneration capacity compared with hDPSC injection.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0362-8) contains supplementary material, which is available to authorized users.

Nanomaterials for Tissue Engineering In Dentistry

The tissue engineering (TE) of dental oral tissue is facing significant changes in clinical treatments in dentistry. TE is based on a stem cell, signaling molecule, and scaffold triad that must be known and calibrated with attention to specific sectors in dentistry. This review article shows a summary of micro- and nanomorphological characteristics of dental tissues, of stem cells available in the oral region, of signaling molecules usable in TE, and of scaffolds available to guide partial or total reconstruction of hard, soft, periodontal, and bone tissues. Some scaffoldless techniques used in TE are also presented. Then actual and future roles of nanotechnologies about TE in dentistry are presented.

Combination of Bioactive Polymeric Membranes and Stem Cells for Periodontal Regeneration: In Vitro and In Vivo Analyses

Regeneration of periodontal tissues requires a concerted effort to obtain consistent and predictable results in vivo. The aim of the present study was to test a new family of bioactive polymeric membranes in combination with stem cell therapy for periodontal regeneration. In particular, the novel polyester poly(isosorbide succinate-co-L-lactide) (PisPLLA) was compared with poly(L-lactide) (PLLA). Both polymers were combined with collagen (COL), hydroxyapatite (HA) and the growth factor bone morphogenetic protein-7 (BMP7), and their osteoinductive capacity was evaluated via in vitro and in vivo experiments. Membranes composed of PLLA/COL/HA or PisPLLA/COL/HA were able to promote periodontal regeneration and new bone formation in fenestration defects in rat jaws. According to quantitative real-time polymerase chain reaction (qRT-PCR) and Alizarin Red assays, better osteoconductive capacity and increased extracellular mineralization were observed for PLLA/COL/HA, whereas better osteoinductive properties were associated with PisPLLA/COL/HA. We concluded that membranes composed of either PisPLLA/COL/HA or PLLA/COL/HA present promising results in vitro as well as in vivo and that these materials could be potentially applied in periodontal regeneration.

Advanced Engineering Strategies for Periodontal Complex Regeneration

The regeneration and integration of multiple tissue types is critical for efforts to restore the function of musculoskeletal complex. In particular, the neogenesis of periodontal constructs for systematic tooth-supporting functions is a current challenge due to micron-scaled tissue compartmentalization, oblique/perpendicular orientations of fibrous connective tissues to the tooth root surface and the orchestration of multiple regenerated tissues. Although there have been various biological and biochemical achievements, periodontal tissue regeneration remains limited and unpredictable. The purpose of this paper is to discuss current advanced engineering approaches for periodontal complex formations; computer-designed, customized scaffolding architectures; cell sheet technology-based multi-phasic approaches; and patient-specific constructs using bioresorbable polymeric material and 3-D printing technology for clinical application. The review covers various advanced technologies for periodontal complex regeneration and state-of-the-art therapeutic avenues in periodontal tissue engineering.

The effect of bacterial cellulose membrane compared with collagen membrane on guided bone regeneration

PURPOSE

This study was to evaluate the effects of bacterial cellulose (BC) membranes as a barrier membrane on guided bone regeneration (GBR) in comparison with those of the resorbable collagen membranes.

MATERIALS AND METHODS

BC membranes were fabricated using biomimetic technology. Surface properties were analyzed, Mechanical properties were measured, in vitro cell proliferation test were performed with NIH3T3 cells and in vivo study were performed with rat calvarial defect and histomorphometric analysis was done. The Mann-Whitney U test and the Wilcoxon signed rank test was used (α<.05).

RESULTS

BC membrane showed significantly higher mechanical properties such as wet tensile strength than collagen membrane and represented a three-dimensional multilayered structure cross-linked by nano-fibers with 60 % porosity. In vitro study, cell adhesion and proliferation were observed on BC membrane. However, morphology of the cells was found to be less differentiated, and the cell proliferation rate was lower than those of the cells on collagen membrane. In vivo study, the grafted BC membrane did not induce inflammatory response, and maintained adequate space for bone regeneration. An amount of new bone formation in defect region loaded with BC membrane was significantly similar to that of collagen membrane application.

CONCLUSION

BC membrane has potential to be used as a barrier membrane, and efficacy of the membrane on GBR is comparable to that of collagen membrane.

Evaluation of an Osseous Allograft Membrane for Guided Tissue Regeneration in the Dog

Clinical application of a demineralized freeze-dried cortical bone membrane allograft (DFBMA) for treatment of intra(infra)bony periodontal pockets in dogs was evaluated. The mean pre-treatment periodontal probing depth equaled 7.2-mm. Post-treatment probing depths in all 11 cases were normal, with a mean periodontal probing gain of 5.4-mm. Guided tissue regeneration using a commercially available veterinary canine DFBMA and canine demineralized freeze-dried bone allograft (DFDBA) resulted in clinically significant periodontal attachment gains. The gain of new periodontal tissue attachment was statistically significant (P < 0.0001). The commercially available veterinary allograft products predictably increased new periodontal attachment without any identified membrane sequelae in these 11 cases.

Induced Pluripotent Stem Cells and Periodontal Regeneration

Periodontitis is a chronic inflammatory disease which leads to destruction of both the soft and hard tissues of the periodontium. Tissue engineering is a therapeutic approach in regenerative medicine that aims to induce new functional tissue regeneration via the synergistic combination of cells, biomaterials, and/or growth factors. Advances in our understanding of the biology of stem cells, including embryonic stem cells and mesenchymal stem cells, have provided opportunities for periodontal tissue engineering. However, there remain a number of limitations affecting their therapeutic efficiency. Due to the considerable proliferation and differentiation capacities, recently described induced pluripotent stem cells (iPSCs) provide a new way for cell-based therapies for periodontal regeneration. This review outlines the latest status of periodontal tissue engineering and highlights the potential use of iPSCs in periodontal tissue regeneration.

Demineralized Dentin as a Semi-Rigid Barrier for Guiding Periodontal Tissue Regeneration

BACKGROUND

Guided tissue regeneration (GTR) is an accepted approach in the correction of periodontal bone loss. Nonetheless, the deficiencies of commonly applied absorbable membrane, such as flexibility and limited osteoconductive and osteoinductive capability, still leave much room for improvement. Thus, the feasibility of applying demineralized dentin tissue to improve the therapeutic effect of GTR in periodontal regeneration was explored.

METHODS

Demineralized dentin was harvested after acid treatment, and its physiochemical properties were assessed in terms of mineralization density, contact angle, three-point test, and cell attachment. Because of its similar characteristics with bone tissue, dentin that had been acid-treated for 6 hours was chosen to repair a periodontal defect using an induced-periodontitis canine model. Histologic measurements were taken to compare its therapeutic effects to an absorbable membrane group and an untreated group.

RESULTS

The demineralized dentin displayed continually decreased hardness and density as the acid etching time was prolonged. Enhanced attachment and spreading of bone marrow mesenchymal stem cells were observed on the 6-hour processed dentin. Furthermore, in the demineralized dentin group, more periodontal tissues were newly formed compared with the biomembrane and untreated groups.

CONCLUSION

Acid etching represents an easy and promising approach to obtain demineralized dentin with desirable properties, similar to bone, for clinical application to promote periodontal tissue regeneration.

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

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

Combination of bone allograft, barrier membrane and doxycycline in the treatment of infrabony periodontal defects: A comparative trial

Aim

The purpose of the present study was to compare the regenerative potential of noncontained periodontal infrabony defects treated with decalcified freeze-dried bone allograft (DFDBA) and barrier membrane with or without local doxycycline.

Methods

This study included 48 one- or two-wall infrabony defects from 24 patients (age: 30–65 years) seeking treatment for chronic periodontitis. Defects were randomly divided into two groups and were treated with a combination of DFDBA and barrier membrane, either alone (combined treatment group) or with local doxycycline (combined treatment + doxycycline group). At baseline (before surgery) and 3 and 6 months after surgery, the pocket probing depth (PPD), clinical attachment level (CAL), radiological bone fill (RBF), and alveolar height reduction (AHR) were recorded. Analysis of variance and the Newman–Keuls post hoc test were used for statistical analysis. A two-tailed p-value of less than 0.05 was considered to be statistically significant.

Results

In the combined treatment group, the PPD reduction was 2.00 ± 0.38 mm (32%), CAL gain was 1.25 ± 0.31 mm (17.9%), and RBF was 0.75 ± 0.31 mm (20.7%) after 6 months. In the combined treatment + doxycycline group, these values were 2.75 ± 0.37 mm (44%), 1.5 ± 0.27 mm (21.1%), and 1.13 ± 0.23 mm (28.1%), respectively. AHR values for the groups without and with doxycycline were 12.5% and 9.4%, respectively.

Conclusion

There was no significant difference in the regeneration of noncontained periodontal infrabony defects between groups treated with DFDBA and barrier membrane with or without doxycycline.

Clinical and radiographic evaluation of nanocrystalline hydroxyapatite with or without platelet-rich fibrin membrane in the treatment of periodontal intrabony defects

Background:

Nano-sized ceramics may represent a promising class of bone graft substitutes due to their improved osseointegrative properties. Nanocrystalline hydroxyapatite (NcHA) binds to bone and stimulate bone healing by stimulation of osteoblast activity. Platelet-rich fibrin (PRF), an intimate assembly of cytokines, glycan chains, and structural glycoproteins enmeshed within a slowly polymerized fibrin network, has the potential to accelerate soft and hard tissue healing. The present study aims to explore the clinical and radiographical outcome of NcHA bone graft with or without PRF, in the treatment of intrabony periodontal defects.

Materials and Methods:

In a split-mouth study design, 20 patients having two almost identical intrabony defects with clinical probing depth of at least 6 mm were selected for the study. Selected sites were randomly divided into two groups. In Group I, mucoperiosteal flap elevation followed by the placement of NcHA was done. In Group II, mucoperiosteal flap elevation, followed by the placement of NcHA with PRF was done. Clinical and radiographic parameters were recorded at baseline and at 6-month postoperatively.

Results:

Both treatment groups showed a significant probing pocket depth (PPD) reduction, clinical attachment gain, increase bone density 6-month after surgery compared with baseline. However, there was a significantly greater PPD reduction and clinical attachment gain when PRF was added to NcHA.

Conclusion:

The NcHA bone graft in combination with PRF demonstrated clinical advantages beyond that achieved by the NcHA alone.

Effects of azithromycin, metronidazole, amoxicillin, and metronidazole plus amoxicillin on an in vitro polymicrobial subgingival biofilm model

Chronic periodontitis is one of the most prevalent human diseases and is caused by dysbiosis of the subgingival microbiota. Treatment involves primarily mechanical disruption of subgingival biofilms and, in certain cases, adjunctive use of systemic antibiotic therapy. In vitro biofilm models have been developed to study antimicrobial agents targeting subgingival species. However, these models accommodate a limited number of taxa, lack reproducibility, and have low throughput. We aimed to develop an in vitro multispecies biofilm model that mimics subgingival plaque, to test antimicrobial agents. Biofilms were cultivated using the Calgary Biofilm Device and were exposed to amoxicillin (AMX), metronidazole (MTZ), azithromycin (AZM), and AMX-MTZ at four different concentrations for 12, 24, or 36 h. Chlorhexidine (CHX) (0.12%) was used as the positive control. The compositions of the biofilms were analyzed by checkerboard DNA-DNA hybridization, and the percent reduction in biofilm metabolic activity was determined using 2,3,5-triphenyltetrazolium chloride and spectrophotometry. Thirty-five of the 40 species used in the inoculum were consistently recovered from the resulting in vitro biofilms. After 36 h of exposure at the 1:27 dilution, AMX-MTZ reduced metabolic activity 11% less than CHX (q = 0.0207) but 54% more than AMX (q = 0.0031), 72% more than MTZ (q = 0.0031), and 67% more than AZM (q = 0.0008). Preliminary evidence of a synergistic interaction between AMX and MTZ was also observed. In summary, we developed reproducible biofilms with 35 subgingival bacterial species, and our results suggested that the combination of AMX and MTZ had greater antimicrobial effects on these in vitro multispecies biofilms than expected on the basis of the independent effects of the drugs.

Electrospun microfiber membranes embedded with drug-loaded clay nanotubes for sustained antimicrobial protection

Guided tissue regeneration/guided bone regeneration membranes with sustained drug delivery were developed by electrospinning drug-loaded halloysite clay nanotubes doped into poly(caprolactone)/gelatin microfibers. Use of 20 wt % nanotube content in fiber membranes allowed for 25 wt % metronidazole drug loading in the membrane. Nanotubes with a diameter of 50 nm and a length of 600 nm were aligned within the 400 nm diameter electrospun fibers, resulting in membranes with doubling of tensile strength along the collector rotating direction. The halloysite-doped membranes acted as barriers against cell ingrows and have good biocompatibility. The metronidazole-loaded halloysite nanotubes incorporated in the microfibers allowed for extended release of the drugs over 20 days, compared to 4 days when directly admixed into the microfibers. The sustained release of metronidazole from the membranes prevented the colonization of anaerobic Fusobacteria, while eukaryotic cells could still adhere to and proliferate on the drug-loaded composite membranes. This indicates the potential of halloysite clay nanotubes as drug containers that can be incorporated into electrospun membranes for clinical applications.

Evaluation of metronidazole-loaded poly(3-hydroxybutyrate) membranes to potential application in periodontitis treatment

Guided tissue regeneration is a technique used for periodontium reconstruction. This technique uses barrier membranes, which prevent epithelial growth in the wound site and may also be used to release antibiotics, to protect the wound against opportunistic infections. Periodontal poly(3-hydroxybutyrate) membranes containing metronidazole (a drug used to help in infection control) were produced and characterized. The kinetic mechanism of the metronidazole delivery of leached and nonleached membrane as well as its cytotoxicity and structural integrity were evaluated. Poly(3-hydroxybutyrate) membranes containing 0.5-2 wt % of the drug and 20 wt % of the plasticizer were manufactured via compression molding. Based on morphological analysis, membranes loaded with 2% metronidazole were considered for detailed studies. The results revealed that metronidazole delivery by the leached membranes seemed to follow the Fick's law. Membranes were noncytotoxic. The amount of metronidazole delivered was in the range of the minimal inhibitory concentration for Porphyromonas gingivalis, and the membranes inhibited the proliferation of these bacteria. Besides, they maintained their mechanical resistance after 30 days of immersion in phosphate buffer at pH 7.4.

Efficacy of Connective Tissue with and without Periosteum in Regeneration of Intrabony Defects

Background and aims. Connective tissue grafts with and without periosteum is used in regenerative treatments of bone and has demonstrated successful outcomes in previous investigations. The aim of present study was to evaluate the effectiveness of connective tissue graft with and without periosteum in regeneration of intrabony defects.

Materials and methods. In this single-blind randomized split-mouth clinical trial, 15 pairs of intrabony defects in 15 patients with moderate to advanced periodontitis were treated by periosteal connective tissue graft + ABBM (test group) or non-periosteal connective tissue graft + ABBM (control group). Probing pocket depth, clinical attachment level, free gingival margin position, bone crestal position, crest defect depth and defect depth to stent were measured at baseline and after six months by surgical re-entry. Data was analyzed by Student’s t-test and paired t-tests (α=0.05).

Results. Changes in clinical parameters after 6 months in the test and control groups were as follows: mean of PPD reduction: 3.1±0.6 (P<0.0001); 2.5±1.0 mm (P<0.0001), CAL gain: 2.3±0.9 (P<0.0001); 2.2±1.0 mm (P<0.0001), bone fill: 2.2±0.7 mm (P<0.0001); 2.2±0.7 mm (P<0.0001), respectively. No significant differences in the position of free gingival margin were observed during 6 months compared to baseline in both groups.

Conclusion. Combinations of periosteal connective tissue graft + ABBM and non-periosteal connective tissue graft + ABBM were similarly effective in treating intrabony defects without any favor for any group. Connective tissue and perio-steum can be equally effective in regeneration of intrabony defects.

Functionalized PCL/HA nanocomposites as microporous membranes for bone regeneration

In the present work, microporous membranes based on poly(ε-caprolactone) (PCL) and PCL functionalized with amine (PCL-DMAEA) or anhydride groups (PCL-MAGMA) were realized by solvent-non solvent phase inversion and proposed for use in Guided Tissue Regeneration (GTR). Nanowhiskers of hydroxyapatite (HA) were also incorporated in the polymer matrix to realize nanocomposite membranes. Scanning Electron Microscopy (SEM) showed improved interfacial adhesion with HA for functionalized polymers, and highlighted substantial differences in the porosity. A relationship between the developed porous structure of the membrane and the chemical nature of grafted groups was proposed. Compared to virgin PCL, hydrophilicity increases for functionalized PCL, while the addition of HA influences significantly the hydrophilic characteristics only in the case of virgin polymer. A significant increase of in vitro degradation rate was found for PCL-MAGMA based membranes, and at lower extent of PCL-DMAEA membranes. The novel materials were investigated regarding their potential as support for cell growth in bone repair using multipotent mesenchymal stromal cells (MSC) as a model. MSC plated onto the various membranes were analyzed in terms of adhesion, proliferation and osteogenic capacity that resulted to be related to chemical as well as porous structure. In particular, PCL-DMAEA and the relative nanocomposite membranes are the most promising in terms of cell-biomaterial interactions.