Guided tissue regeneration update

Optimizing esthetic zone periodontal regeneration in a 1-2-wall infrabony defect using recombinant human platelet-derived growth factor BB and β-tricalcium phosphate: A case report

OBJECTIVE

Periodontitis is an inflammatory condition induced by subgingival bacterial dysbiosis, resulting in inflammatory-mediated destruction of tooth-supporting structures, potentially leading to the formation of infrabony defects. This case report describes the treatment of a patient who presented with a combination 1-2-wall defect on tooth 21. To maintain the residual periodontal attachment and minimize esthetic consequences, a regenerative approach was performed using recombinant human platelet-derived growth factor-BB (rh-PDGF-BB) and β-tricalcium phosphate (β-TCP).

MATERIALS AND METHODS

At the time of postscaling/root planing reevaluation, a 34-year-old Asian male initially diagnosed with molar/incisor pattern stage III grade C periodontitis exhibited a 6-mm residual probing depth on the mesiopalatal aspect of tooth 21. Periodontal regenerative surgery was performed using rh-PDGF-BB with β-TCP, without the use of a membrane.

RESULTS

At the 1-year follow-up, a significant reduction in probing depth and radiographic evidence of bone fill were observed. Additionally, re-entry surgery for implant placement at site tooth 23 confirmed bone fill in the defect on tooth 21.

CONCLUSION

These results demonstrate the efficacy of rh-PDGF-BB with β-TCP in enhancing periodontal regeneration and support its use as a treatment option when treating poorly contained infrabony defects in the esthetic zone.

The improvement of periodontal tissue regeneration using a 3D-printed carbon nanotube/chitosan/sodium alginate composite scaffold

Periodontal disease is a common disease in the oral field, and many researchers are studying periodontal disease and try to find some biological scaffold materials to make periodontal tissue regenerative. In this study, we attempted to construct a carbon nanotube/chitosan/sodium alginate (CNT/CS/AL) ternary composite hydrogel and then prepare porous scaffold by 3D printing technology. Subsequently, characterizing the materials and testing the mechanical properties of the scaffold. Additionally, its effect on the proliferation of human periodontal ligament cells (hPDLCs) and its antibacterial effect on Porphyromonas gingivalis were detected. We found that CNT/CS/AL porous composite scaffolds with uniform pores could be successfully prepared. Moreover, with increasing CNT concentration, the degradation rate and the swelling degree of scaffold showed a downward trend. The compressive strength test indicated the elastic modulus of composite scaffolds ranged from 18 to 80 kPa, and 1% CNT/CS/AL group had the highest quantitative value. Subsequently, cell experiments showed that the CNT/CS/AL scaffold had good biocompatibility and could promote the proliferation of hPDLCs. Among 0.1%-1% CNT/CS/AL groups, the biocompatibility of 0.5% CNT/CS/AL scaffold performed best. Meanwhile, in vitro antibacterial experiments showed that the CNT/CS/AL scaffold had a certain bacteriostatic effect on P. gingivalis. When the concentration of CNT was more than 0.5%, the antimicrobial activity of composite scaffold was significantly promoted, and about 30% bacteria were inactivated. In conclusion, this 3D-printed CNT/CS/AL composite scaffold, with good material properties, biocompatibility and bacteriostatic activity, may be used for periodontal tissue regeneration, providing a new avenue for the treatment of periodontal disease.

Periodontal ligament stem cell isolation protocol: A systematic review

Despite the plethora of literature regarding isolation and characterization of periodontal ligament stem cells (PDLSCs), due to the existence of controversies in the results, in this comprehensive review, we aimed to summarize and compare the effect of isolation methods on PDLSC properties, including clonogenicity, viability/proliferation, markers expression, cell morphology, differentiation, and regeneration. Moreover, the outcomes of included studies, considering various parameters such as teeth developmental stages, donor age, periodontal ligament health status, and part of the teeth root from which PDLSCs were derived, have been systematically discussed. It has been shown that from included studies PDLSCs can be isolated from teeth from any developmental stages, any health status condition, and any donor age. Also, a non-enzymatic digestion method, named as an explant or outgrowth technique, is a suitable protocol for of PDLSCs isolation.

Texturized P(VDF-TrFE)/BT membrane enhances bone neoformation in calvaria defects regardless of the association with photobiomodulation therapy in ovariectomized rats

OBJECTIVES

The purpose of this investigation was to evaluate in vivo the response of bone tissue to photobiomodulation when associated with texturized P(VDF-TrFE)/BT in calvaria defects of ovariectomized rats.

MATERIALS AND METHODS

Wistar Hannover rats were submitted to ovariectomy/control surgery. Calvaria bone defects of 5-mm diameter were performed after 90 days of ovariectomy. The animals were divided into OVX (without laser (L) and membrane), OVX + P(VDF-TrFE)/BT, OVX + P(VDF-TrFE)/BT + L, and OVX + PTFE + L. It was utilized a low-intensity gallium-aluminum-arsenide laser (GaAlAs) with 780-nm wavelength and 30-J/cm² energy density in 12 sessions (120 s). Thirty days after the bone defect the animals were euthanized for histological, microtomographic, and molecular evaluation. Quantitative analysis was analyzed by statistical software for p < 0.05.

RESULTS

Histological parameters showed bone tissue formation at the borders of all group defects. The association of photobiomodulation and texturized P(VDF-TrFE)/BT was not synergistic and did not show significant changes in morphometric analysis and biomarkers gene expression. Nevertheless, texturized P(VDF-TrFE)/BT membrane enhanced bone repair regardless of the association with photobiomodulation therapy, with an increase of connectivity density when compared to the OVX + PTFE + L group. The association of photobiomodulation therapy and PTFE was synergistic, increasing the expression of Runx2, Alp, Bsp, Bglap, Sp7, and Rankl, even though not enough to reflect significance in the morphometric parameters.

CONCLUSIONS

The utilization of texturized P (VDF-TrFE)/BT, regardless of the association with photobiomodulation therapy, enhanced bone repair in an experimental model of osteoporosis.

A Facile Synthesis Process and Evaluations of α-Calcium Sulfate Hemihydrate for Bone Substitute

Alpha-calcium sulfate hemihydrate (α-HH) has been used effectively in grafting through its desired features to support bone regeneration. In recent years, many synthetic methods have been proposed. Among them, the autoclave method for manufacturing α-HH is best suited for cost-savings due to its simple operation and limited use of additives. Despite these advantages, the synthesis of surgical grade products without the use of any additives has not yet been clearly discussed. In this study, surgical grade α-HH was successfully produced from calcium sulfate dihydrate (DH) using the autoclave method at an elevated temperature and pressure. The synthesized powder had a high purity of about 98.62% α-HH with a prismatic morphology (20.96 ± 8.83 µm in length and 1.30 ± 0.71 µm in diameter). The screening tests, in simulated body fluid (SBF) solution, for the product properties showed no bioactivity, and fast degradation accompanied by a slight decrease in pH. The lactate dehydrogenase (LDH) assay showed good biocompatibility of the material, however, its potential for cytotoxicity was also observed in NIH 3T3 cells. Briefly, despite some unfavorable properties, the autoclave-synthesized α-HH is a promising bone graft substitute that can be applied in orthopedic and maxillofacial surgeries.

Fabrication and In Vitro Characterization of Bioactive Glass/Nano Hydroxyapatite Reinforced Electrospun Poly(ε-Caprolactone) Composite Membranes for Guided Tissue Regeneration

Background: Current resorbable and non-resorbable membranes act as a physical barrier to avoid connective and epithelial tissue downgrowth into the defect, favoring the regeneration of periodontal tissues. These conventional membranes possess many structural and bio-functional limitations. We hypothesized that the next-generation of guided tissue regeneration (GTR) membranes for periodontal tissue engineering will be a biologically active, spatially designed nanofibrous biomaterial that closely mimics the native extra-cellular matrix (ECM). Methods: GTR membranes made of poly(ε-Caprolactone) with a molecular weight of 80,000 reinforced with different weight concentrations of nano-Hydroxyapatite/Bioactive glass (2%, 5%, 10%, 15%) is fabricated by the method of electrospinning. After fabrication, in vitro properties are evaluated. Results: The electrospun nanofibrous membranes possessed excellent mechanical properties initially and after one month of degradation in phosphate buffer solution (PBS). Moreover, none of the fabricated membranes were found to be cytotoxic at lower concentrations and higher concentrations. Comparing the overall properties, PCL (poly(e-caprolactone)) + BG (Bioactive glass) 2% exhibited superior cell attachment and percentage of viable cells, increased fiber and pore diameter which satisfies the ideal properties needed for GTR membranes. Conclusion: Composite nanofibrous membranes prepared by electrospinning are suitable for use as a GTR membrane and are a useful prototype for further development of a final membrane for clinical use.

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.

The Effect of Resection Angle on Stress Distribution after Root-End Surgery

Introduction:

This study aimed to investigate the influence of the resection angle on the stress distribution of retrograde endodontic treated maxillary incisors under oblique-load application.

Methods and Materials:

A maxillary central incisor which was endodontically treated and restored with a fiber glass post was obtained in a 3-dimensional numerical model and distributed into three groups according to type of resection: control; restored with fiber post without retrograde obturation, R45 and R90 with 45º and 90º resection from tooth axial axis, respectively and restored with Fuji II LC (GC America). The numerical models received a 45^º occlusal load of 200 N/cm² on the middle of lingual surface. All materials and structures were considered linear elastic, homogeneous and isotropic. Numerical models were plotted and meshed with isoparametric elements, and the results were analyzed using maximum principal stress (MPS).

Results:

MPS showed greater stress values in the bone tissue for control group than the other groups. Groups with apicectomy showed acceptable stress distribution on the fiber post, cement layer and root dentin, presenting more improved values than control group.

Conclusion:

Apicectomy at 90^º promotes more homogeneity on stress distribution on the fiber post, cement layer and root dentin, which suggests less probability of failure. However, due to its facility and stress distribution also being better than control group, apicectomy at 45^° could be a good choice for clinicians.

Cytotoxicity and migration of fibroblasts on two types of calcium sulfate dihydrate

AIM

The aim of the present study was to compare cytotoxicity and migration ability of L929 on medical-grade calcium sulfate dihydrate (MCS) with commercial calcium sulfate dihydrate (CCS).

METHODS

Samples of both freshly-mixed and set states of MCS and CCS were extracted in culture medium and tested for cytotoxicity according to International Organization of Standardization 10993-5:2009. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used, and the percentage of cell viability was calculated. Thirty petri dishes were divided into three equal groups: polystyrene (control), CCS, and MCS. In each petri dish, triplicate wells were made on the agarose overlay on the material. The central well was occupied with L929 cell suspension, one well was filled with platelet-derived growth factor-BB, and the remaining well with Hanks' Balanced Salt Solution. After incubation, the migration distances were measured and the corrected migration distances were calculated. The final step involved scanning electron microscopy (SEM).

RESULTS

The CCS had significantly less cell viability than MCS at a high extracted concentration (P < 0.001) in both samples. The mean corrected migration of MCS was significantly greater than that of CCS (P < 0.05). SEM showed that L929 cells on MCS exhibited an elongated spindle shape.

CONCLUSION

MCS was less cytotoxic and provided greater migration of L929 fibroblasts compared with CCS.

Management of large preiapical lesion with the combination of second generation platelet extract and hydroxyapatite bone graft: a report of three cases

The pulp tissue necrosis and extensive periodontal diseases leads to the development of the inflammatory periapical lesion which causes a local response of bone around the apex of the tooth. Depends upon the nature of wound and available biological growth factors the outcome will be either regeneration or repair. Being a rich source of growth factors, platelet rich fibrin (PRF) posses many advantages in bone regeneration. The purpose of this case report is to present an attempt to evaluate the healing potential of the combination of PRF and Hydroxyapatite bone graft as opposed to using these materials alone. A periapical endodontic surgery was performed on three patients with a large periapical inflammatory lesion and a large bony defect. The defect was then filled with a combination of PRF and Hydroxyapatite bone graft crystals. Clinical examination exhibited uneventful wound healing. The HA crystals have been replaced by new bone radiographically at the end of two years in Case 1 and Case 2, Case 3 were followed upto one year. On the basis of our cases outcome, we conclude the use of PRF in combination with HA crystals might have accelerate the bone regeneration.

Poly(vinylidene-trifluoroethylene)/barium titanate composite for in vivo support of bone formation

In this study, we evaluated the effect of poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane on in vivo bone formation. Rat calvarial bone defects were implanted with P(VDF-TrFE)/BT and polytetrafluoroethylene (PTFE) membranes, and at 4 and 8 weeks, histomorphometric and gene expression analyses were performed. A higher amount of bone formation was noticed on P(VDF-TrFE)/BT compared with PTFE. The gene expression of RUNX2, bone sialoprotein, osteocalcin, receptor activator of nuclear factor-kappa B ligand, and osteoprotegerin indicates that P(VDF-TrFE)/BT favored the osteoblast differentiation compared with PTFE. These results evidenced the benefits of using P(VDF-TrFE)/BT to promote new bone formation, which may represent a promising alternative to be employed in guided bone regeneration.

Combination of platelet rich fibrin, hydroxyapatite and PRF membrane in the management of large inflammatory periapical lesion

Periapical inflammatory lesion is the local response of bone around the apex of tooth that develops after the necrosis of the pulp tissue or extensive periodontal disease. The final outcome of the nature of wound healing after endodontic surgery can be repair or regeneration depending on the nature of the wound; the availability of progenitor cells; signaling molecules; and micro-environmental cues such as adhesion molecules, extracellular matrix, and associated non-collagenous protein molecules. The purpose of this case report is to add knowledge to the existing literature about the combined use of graft material [platelet rich fibrin (PRF) and hydroxyapatite (HA)] and barrier membrane in the treatment of large periapical lesion. A periapical endodontic surgery was performed on a 45 year old male patient with a swelling in the upper front teeth region and a large bony defect radiologically. The surgical defect was filled with a combination of PRF and HA bone graft crystals. The defect was covered by PRF membrane and sutured. Clinical examination revealed uneventful wound healing. Radiologically the HA crystals have been completely replaced by new bone at the end of 2 years. On the basis of the results obtained in our case report, we hypothesize that the use of PRF in conjunction with HA crystals might have accelerated the resorption of the graft crystals and would have induced the rapid rate of bone formation.

Response of human alveolar bone-derived cells to a novel poly(vinylidene fluoride-trifluoroethylene)/barium titanate membrane

This study investigated the response of human alveolar bone-derived cells to a novel poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane. Osteoblastic cells were cultured in osteogenic conditions either on P(VDF-TrFE)/BT or polytetrafluoroethylene (PTFE) for up to 14 days. At 7 and 14 days, the mRNA expression of Runt-related transcription factor 2 (RUNX2), Type I collagen (COL I), Osteopontin (OPN), Alkaline phosphatase (ALP), Bone sialoprotein (BSP), and Osteocalcin (OC), key markers of the osteoblastic phenotype, and of Bcl2-associated X protein (Bax), B-cell CLL/lymphoma 2 (Bcl-2), and Survivin (SUR), associated with the control of the apoptotic cell death, was assayed by real-time PCR. In situ ALP activity was qualitatively evaluated by means of Fast red staining. Surface characterization was also qualitatively and quantitatively assayed in terms of topography, roughness, and wettability. Cells grown on P(VDF-TrFE)/BT exhibited a significantly higher mRNA expression for all markers compared to the ones on PTFE, except for Bcl-2, which was not detected for both groups. Additionally, Fast red staining was noticeably stronger in cultures on P(VDF-TrFE)/BT at 7 and 14 days. At micron- and submicron scale, SEM images and roughness analysis revealed that PTFE and P(VDF-TrFE)/BT exhibited a smooth topography and a similar roughness, respectively. PTFE membrane displayed higher contact angles compared with P(VDF-TrFE)/BT, as indicated by wettability assay. The novel P(VDF-TrFE)/BT membrane supports the acquisition of the osteoblastic phenotype in vitro, while up-regulating the expression of apoptotic markers. Further in vivo experiments should be carried out to confirm the capacity of P(VDF-TrFE)/BT membrane in promoting bone formation in guided bone regeneration.

Ovine periodontal ligament stem cells: isolation, characterization, and differentiation potential

Periodontal disease leads to destruction of the connective tissues responsible for restraining teeth within the jaw. To date, various conventional therapies for periodontal regeneration have shown limited and variable clinical outcomes. Recent studies have suggested that newly identified human periodontal ligament stem cells (PDLSCs) may offer an alternate and more reliable strategy for the treatment of periodontal disease using a cell-based tissue engineering approach. In the present study, we generated enriched preparations of PDLSCs derived from ovine periodontal ligament using immunomagnetic bead selection, based on expression of the mesenchymal stem cell-associated antigen CD106 (vascular cell adhesion molecule 1). These CD106+ ovine PDLSCs demonstrated the capacity to form adherent clonogenic clusters of fibroblast-like cells when plated at low densities in vitro. Ex vivo-expanded ovine PDLSCs exhibited a high proliferation rate in vitro and expressed a phenotype (CD44+, CD166+, CBFA-1+, collagen-I+, bone sialoprotein+) consistent with human-derived PDLSCs. Furthermore, cultured ovine PDLSCs expressed high transcript levels of the ligament/tendon-specific early transcription factor scleraxis. Importantly, ex vivo-expanded ovine PDLSCs demonstrated the capacity to regenerate both cementum-like mineral and periodontal ligament when transplanted into NOD/SCID mice. The results from the present study suggest that ovine PDLSCs may potentially be used as a novel cellular therapy to facilitate successful and more predictable regeneration of periodontal tissue using an ovine preclinical model of periodontal disease as a prelude to human clinical studies.

Periosteal grafts as barriers in periradicular surgery: report of two cases

AIM

To describe the usefulness of periosteal grafts as barriers for bone regeneration in periradicular surgery when advanced periodontal breakdown occurs.

SUMMARY

The treatment of advanced periodontal breakdown as a result of an associated endodontic lesion constitutes a multifaceted challenge to the clinician. If the source of the irritation cannot be removed by orthograde endodontic treatment, nonsurgical and surgical endodontic/periodontal intervention may be required. Two cases with suppurative chronic apical periodontitis with apicomarginal communication are described. Clinical and radiological evaluations were completed immediately prior to surgery, a week later and every 2 months after surgery for 10 months. Both patients were treated using split-thickness flaps and lateral displacement of the periosteum prior to suturing, in order to close the communication between the oral and the periapical surroundings. A remission of the clinical signs and symptoms, and successful healing in the short-term were achieved in these cases.

KEY LEARNING POINTS

Periapical and periodontal lesions are closely related through pathways of communication. Disruption of the cortical plate and the presence of dentoalveolar sinus tracts can have a deleterious effect on the regeneration process after periradicular surgery. The adoption of supplementary periodontal surgical techniques may help to solve some of the difficulties in the healing process in periradicular surgery. Periosteal grafts have been shown to have the potential to stimulate bone formation when used as a graft material.

Effect of GBR and fixture installation on gingiva and bone levels at adjacent teeth

Guided bone regeneration (GBR) is frequently used in oral implantology. It is unclear to what extent GBR affects the periodontium of adjacent teeth. Therefore, the present study quantifies changes in the proximal gingiva and bone levels at these teeth in 30 patients. Staged surgery involved a standard GBR treatment, randomly using resorbable membranes with a bone substitute or non-resorbable membranes with or without a bone substitute, followed by fixture installation at 6 months and abutment connection a further 6 months later. The data were sampled at each surgery and analysed using MANOVA. Twelve months after GBR, there was on average a small but statistically significant amount of proximal gingival recession (0.75 mm) and bone resorption (0.34 mm) observed, of which 50% was the result of GBR surgery. No significant differences were found between the different GBR treatment modalities. It is concluded that GBR treatment may have a small negative effect on the levels of the free gingival margin and alveolar bone at adjacent teeth, which is in most patients not clinically relevant.

In vitro effect of platelet-derived growth factor-BB on collagen synthesis and proliferation of human periodontal ligament cells

OBJECTIVES

Platelet-derived growth factor (PDGF)-BB is a polypeptide growth factor which has been shown to stimulate periodontal regeneration. In this study, we investigated the time- and dose-dependent effect of PDGF-BB on the proliferation and collagen synthesis of human periodontal ligament (PDL) cells.

MATERIALS AND METHODS

For the proliferation assay, PDL cells were cultured in 0.01-10 ng ml(-1) of PDGF-BB for 12 or 24 h, and cell numbers were counted. For the collagen synthesis assay, PDL cells were cultured in 0.1-10 ng ml(-1) of PDGF-BB for 1 to 24 h. The ratio of collagen content in total protein was evaluated, and the gene expression of type I collagen was assessed quantitatively by Northern blotting analysis.

RESULT AND CONCLUSIONS

PDGF-BB stimulated the proliferation of PDL cells in a time- and dose-dependent manner with the maximum effect at 10 ng ml(-1). PDGF-BB induced the collagen synthesis of PDL cells with the maximum effect for 24-h treatment, and 1 ng ml(-1) of PDGF-BB. PDGF-BB exhibits an inverse dose-dependent effect on proliferation and collagen synthesis by PDL cells. These findings suggest that PDGF-BB is one of the important regulators of the maintenance of the extracellular matrix in PDL, and may play an important role in the regeneration of PDL.

Comparison between a conventional technique and two bone regeneration techniques in periradicular surgery

AIM

The aim was to demonstrate the efficacy of two materials for bone regeneration during periradicular surgery and their effects on the healing of periapical tissues.

METHODOLOGY

Twenty-eight patients (30 surgical sites) were selected and distributed into three groups:group A, conventional technique; group B, conventional technique plus nonbioabsorbable GoreTex R Augmentation membrane; and group C, conventional technique plus the same membrane placed over a synthetic bioactive resorbable graft of a hydroxylapatite (OsteoGen) product in the bony defect. Clinical and radiological evaluations were completed immediately prior to surgery, a week later and every 3 months after surgery up to 12 months. Two histological evaluations were performed (at the beginning and at 12 months).

RESULTS

The results showed complete clinical and radiographic healing (eight cases) for group C, with histologic evidence of trabecular bone in all cases. For group B, six out of nine cases showed complete radiographic healing, incomplete in one case and uncertain in two cases, with histologic evidence of trabecular bone in five out of eight cases, scar tissue in one case and granuloma in two cases. For group A, there was complete radiographic healing in four out of nine cases, incomplete in four and unsuccessful in one case, with evidence of granuloma in four out of eight, scar tissue in two cases and trabecular bone in two cases.

CONCLUSIONS

It was concluded that the conventional technique was less predictable in its healing response during the 12 months of this study. The use of bone regeneration materials, such as nonbioabsorbablemembranes and resorbable hydroxylapatite improved the predictability of clinical, radiographic and histological healing.