Enhancing guided tissue regeneration of periodontal defects by using a novel perforated barrier membrane

Effects of intentional early dense-polytetrafluoroethylene membrane removal on vertical ridge augmentation

BACKGROUND

Vertical ridge augmentation (VRA) requires long healing times for bone maturation. This case study deals with the intentional early removal of a titanium-reinforced dense polytetrafluoroethylene (TR-dPTFE) membrane that allowed for treatment times reduction and improvement of bone quality.

METHODS

A TR-dPTFE membrane was used for VRA in the premolar region of the upper right maxilla. The defect was filled with a mix of particulate autogenous bone and porcine xenograft in a 1:1 ratio. After a 4-month uneventful healing period, the membrane was removed, and the thick keratinized palatal tissue was moved toward the buccal side via a pedicle flap. Implants insertion and healing abutments application were carried out 3 months later, when bone graft could have been revascularized and nourished by the periosteum.

RESULTS

The histologic evaluation of a bone sample harvested during implant bed preparation revealed a huge amount of mature newly formed bone even in the most coronal part. Two screw-retained crowns were delivered 2 months after implant insertion and the 3.5-year follow-up showed perfectly maintained hard and soft tissues.

CONCLUSIONS

Intentional early removal of TR-dPTFE membrane after a 4-month healing time, with simultaneous soft tissue augmentation via a buccally reposioned pedicle flap, allowed graft revascularization from the periosteum, and resulted in optimal quantity and quality of the regenerated bone. This process shortened the overall treatment times, taking only 9 months from VRA to prosthetic loading. Both augmented hard and soft tissues allowed for crestal bone maintenance around implants.

KEY POINTS

Titanium-reinforced dense polytetrafluoroethylene (TR-dPTFE) membranes, due to their closed structure, do not allow the passage of cells and vessels from the periosteum, and revascularization from the residual bone alone is not enough for proper graft maturation and long-term crestal bone maintenance. Early removal of TR-dPTFE membrane allows graft revascularization from the periosteum, and results in optimal quantity and quality of the regenerated bone. Increasing the thickness of the soft tissues, increasing the width of the keratinized mucosa, and repositioning the mucogingival line, via a free gingival graft or a pedicle flap, should be performed simultaneously in the membrane removal phase to reduce the number of surgical interventions, decrease patient morbidity, and shorten the total treatment time.

Nanoscale β-TCP-Laden GelMA/PCL Composite Membrane for Guided Bone Regeneration

Major advances in the field of periodontal tissue engineering have favored the fabrication of biodegradable membranes with tunable physical and biological properties for guided bone regeneration (GBR). Herein, we engineered innovative nanoscale beta-tricalcium phosphate (β-TCP)-laden gelatin methacryloyl/polycaprolactone (GelMA/PCL-TCP) photocrosslinkable composite fibrous membranes via electrospinning. Chemo-morphological findings showed that the composite microfibers had a uniform porous network and β-TCP particles successfully integrated within the fibers. Compared with pure PCL and GelMA/PCL, GelMA/PCL-TCP membranes led to increased cell attachment, proliferation, mineralization, and osteogenic gene expression in alveolar bone-derived mesenchymal stem cells (aBMSCs). Moreover, our GelMA/PCL-TCP membrane was able to promote robust bone regeneration in rat calvarial critical-size defects, showing remarkable osteogenesis compared to PCL and GelMA/PCL groups. Altogether, the GelMA/PCL-TCP composite fibrous membrane promoted osteogenic differentiation of aBMSCs in vitro and pronounced bone formation in vivo. Our data confirmed that the electrospun GelMA/PCL-TCP composite has a strong potential as a promising membrane for guided bone regeneration.

The impact of membrane perforation and L-PRF for vertical ridge augmentation with a xenogeneic block graft: an experimental study in a canine model

OBJECTIVES

This study evaluated clinically and histologically the efficacy of modified perforated collagen membrane (PCM) and/or leukocyte- and platelet-rich fibrin (L-PRF) in combination with xenogeneic block bone graft in the vertical alveolar ridge augmentation.

MATERIALS AND METHODS

Six adult mongrel dogs were enrolled in this randomized blinded study. After defect preparation, xenogeneic screw-fixed block graft was covered by an occlusive collagen membrane in group 1 that represented the control group (Block + CM). In group 2, L-PRF membrane was added first before top coverage by occlusive collagen membrane (Block + L-PRF + CM). Groups 3 (Block + PCM) and 4 (Block + L-PRF + PCM) were identical to the first two groups except that the occlusive collagen membrane was replaced by a perforated one. Following a healing period of 2 months, the dogs were submitted to the surgical reentry phase for clinical and histological evaluation.

RESULTS

Clinically, no significant differences were found among all groups regarding vertical and horizontal ridge dimensions (p = 0.155, 0.492, respectively). Histomorphometric analysis revealed that the percentage of the total bone area and mature bone was significantly higher in group 4 (69.36 ± 2.72, 33.11 ± 5.18) compared to the control group (59.17 ± 4.27, 21.94 ± 2.86) (p = 0. 027, p = 0.029).

CONCLUSION

The use of xenogenic block grafts in combination with a double-layered perforated collagen L-PRF membrane in vertical ridge augmentation appeared to improve the inductive power of this challenging defect type.

CLINICAL RELEVANCE

Size and number of perforations may affect the mechanical and handling properties of the membrane.

Predictability and Clinical Stability of Barrier Membranes in Treatment of Periodontal Intrabony Defects: A Systematic Review and Meta-Analysis

The adjunctive use of GTR membranes helps us to achieve predictable periodontal regeneration. The aim of this systematic review was to evaluate and compare the treatment efficacy of resorbable versus non-resorbable barrier membranes used in guided tissue regeneration in the treatment of intrabony defects in chronic periodontitis patients. The following databases were searched: Medline, the Cochrane Central Register of Controlled Trails (CENTRAL), SCOPUS, EMBASE. Randomized clinical trials (RCTs) published in English languages over the past 25 years were included. The primary outcomes assessed were: change of probing pocket depth (PD), change in clinical attachment level (CAL) and gingival recession coverage (GRC), and intrabony defect fill (IBDF). A total of eight RCTs were included for systematic review. The outcome of GR at a six-month interval revealed a significant difference in treatment effect with a mean difference of 0.42, 95% CI [0.02, 0.81]; Z = 2.09, (p = 0.04) favouring the resorbable membrane group. The intrabony defect depth fill at a 12-month interval revealed a significant difference in treatment effect with MD of 0.79, p = 0.00001; favoring the resorbable membrane group. The resorbable membrane showed a significant improvement in gingival recession coverage and intrabony defect fill, owing to its advantage of avoiding the second surgical intervention.

Hard and soft tissue augmentation of vertical ridge defects with the “hard top double membrane technique”: introduction of a new technique and a case report

<abstract> <p>Vertical ridge defects (VRD) of the jaws often require both bone and keratinized mucosa (KM) reconstruction. A new staged procedure is proposed to restore both hard and soft tissues in the VRD through a case report. A patient required the lower right second premolar and first molar rehabilitation. The first surgery aimed to restore the bone architecture through the use of a titanium reinforced dense-PTFE (TR-dPTFE) membrane, positioned and stabilized on top of tenting screws. This membrane didn't cover the whole defect, it just created an hard top that avoided the collapse of a collagen membrane that was placed over it. This resorbable membrane was stabilized with tacks and covered the whole defect, protecting a mixture of autogenous bone and porcine xenograft both lingually and buccally. The second surgery was performed after a 5 month healing time either to remove the tenting screws and the TR-dPTFE membrane, and to augment KM with a gingival graft harvested from the palate. Both regenerated hard and soft tissues were left to mature for 7 months before the third surgery. In this last stage implants insertion and healing abutments application were carried out in a straightforward way, since bone and KM had been previously restored. Two bone samples, harvested for histologic evaluation, stated a great amount of new bone formation. This new approach allowed inserting implants in matured and stable regenerated bone and augmented KM, avoiding the hard and soft tissue loss around implant neck that can affect the VRD treatments during healing.</p> </abstract>

Osteoconductive properties of upside-down bilayer collagen membranes in rat calvarial defects

Background

Bilayer collagen membranes are routinely used in guided bone/tissue regeneration to serve as osteoconductive scaffolds and prevent the invasion of soft tissues. It is recommended to place the membranes with their dense layer towards the soft tissue and their porous layer towards the bony defect area. However, evidence supporting this recommendation is lacking. This study aimed to determine whether the alignment of bilayer collagen membranes has an effect on bone regeneration.

Methods

In two groups of ten male Sprague-Dawley rats each, a 5-mm calvarial defect was created. Thereafter, the defect was randomly covered with a bilayer, resorbable, pure type I and III collagen membrane placed either regularly or upside-down (i.e., dense layer towards bone defect). After 4 weeks of healing, micro-computed tomography (μCT), histology, and histomorphometry of the inner cylindrical region of interest (4.5 mm in diameter) were performed to assess new bone formation and the consolidation of the collagen membrane in the defect area.

Results

Quantitative μCT showed similar bone volume (median 8.0 mm³, interquartile range 7.0–10.0 vs. 6.2 mm³, 4.3–9.4, p = 0.06) and trabecular thickness (0.21 mm, 0.19–0.23 vs. 0.18 mm, 0.17–0.20, p = 0.03) between upside-down and regular placement, both leading to an almost complete bony coverage. Histomorphometry showed comparable new bone areas between the upside-down and regularly placed membranes, 3.9 mm² (2.7–5.4) vs. 3.8 mm² (2.2–4.0, p = 0.31), respectively. Both treatment groups revealed the same regeneration patterns and spatial distribution of bone with and without collagen fibers, as well as residual collagen fibers.

Conclusions

Our data support the osteoconductive properties of collagen membranes and suggest that bone regeneration is facilitated regardless of membrane layer alignment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-021-00333-y.

Comparison of the Migration Potential through Microperforated Membranes of CD146+ GMSC Population versus Heterogeneous GMSC Population

Background

Guided tissue regeneration (GTR) is a powerful modality for periodontal regeneration, but it blocks the periosteum and gingival stem cells (GMSCs), from supporting periodontal wound by the nutrients, growth factors, and regenerative cells. The microperforated membrane considered a rewarding solution for this major drawback; GMSCs can migrate through a GTR microperforated membrane toward a chemoattractant, with the blocking of other unfavorable epithelial cells and fibroblasts. In the absence of a sole marker for MSC, a homogeneous population of GMSC is difficult to isolate; using CD146 as confirmatory markers for MSC identification, testing the behaviour of such homogeneous population in migration dynamics was the question to answer in this study.

Materials and Methods

GMSCs from healthy crown lengthening tissue was isolated (n = 3), its stem cell nature was confirmed, CD146 and CD271 markers were confirmatory markers to confirm homogenous stem cell population, and magnetic sorting was used to isolate GMSC with CD146 markers. A homogenous CD146 population was compared to heterogeneous GMSCs of origin; the population doubling time and MTT test of the two populations were compared. Migration dynamics were examined in a transwell migration chamber through 8 μm perforated polycarbonic acid membrane, and 0.4 μm and 3 μm perforated collagen-coated polytetrafluoroethylene membrane (PTFE) and 10% fetal bovine serum (FBS) were the chemoattractants used in the lower compartment to induce cell migration, were incubated in a humidified environment for 24 hours, then migrated the cell in the lower compartment examined by a light and electron microscope.

Results

GMSCs fulfilled all the minimal criteria of stem cells and showed low signal 10% for CD146 on average and extremely low signal 2% for CD271 on average. Magnetic sorting optimized the signal of CD146 marker to 55%. GMSC CD146 population showed nonstatistically significant shorter population doubling time. CD146 homogeneous population migrated cell numbers were statistically significant compared to the heterogeneous population, through 0.4 μm and 3 μm perforated collagen membrane and 8 μm perforated polycarbonate membrane. Scanning electron microscopy proved the migration of the cells.

Conclusions

A subset of the isolated GMSC showed a CD146 marker, which is considered a dependable confirmatory marker for the stem cells. In terms of GMSC migration through the microperforated membrane, a homogeneous CD146 population migrates more statistically significant than a heterogeneous GMSC population.

Regenerative potential of cultured gingival fibroblasts in treatment of periodontal intrabony defects (randomized clinical and biochemical trial)

BACKGROUND

Defective cellular elements constitute an important challenge to achieve predictable periodontal regeneration. In an attempt to improve the cellularity of periodontal defects, gingival fibroblasts were implanted without their associated extracellular elements in periodontal defects to expose them to periodontal tissue mediators. In order to investigate the regenerative potential of gingival fibroblasts translocated into periodontal defects, the present study was designed to clinically and biochemically investigate the use of gingival fibroblasts (GF) and their associated mesenchymal stem cells (GMSC) in the treatment of intrabony periodontal defects.

METHODS

A total of 20 subjects were randomly divided into two groups (n = 20). Group I: ten patients were included with ten intrabony periodontal defects that received β-calcium triphosphate (β-TCP) followed by collagen membrane defect coverage, while group II: (10 patients) ten periodontal defects received cultured gingival fibroblasts (GF) on the β-TCP scaffold and covered by a collagen membrane. The clinical evaluation was carried out at the beginning and at 6 months. Gingival crevicular fluid (GCF) samples were collected directly from the test sites for the quantitative measurement of PDGF-BB and BMP-2 using the ELISA kit at 1, 7, 14, and 21 days after surgery.

RESULTS

Group II reported a significantly greater reduction in vertical pocket depth (VPD) and CAL gain compared with group I after 6 months. Radiographic bone gain was statistically higher in group II compared with group I. A significantly higher concentration of PDGF-BB was observed in group II on days 1, 3, and 7 compared with group I.

CONCLUSIONS

Translocation of gingival fibroblasts from gingival tissue to periodontal defects could be a promising option that increases cellular elements with regeneration potential. The concept of total isolation of gingival fibroblasts using occlusive membranes must be re-evaluated.

Effect of Inflammation on Gingival Mesenchymal Stem/Progenitor Cells' Proliferation and Migration through Microperforated Membranes: An In Vitro Study

Background

In the field of periodontal guided tissue regeneration, microperforated membranes have recently proved to be very promising periodontal regenerative tissue engineering tools. Regenerative periodontal approaches, employing gingival mesenchymal stem/progenitor cells in combination with these novel membranes, would occur mostly in inflamed microenvironmental conditions intraorally. This in turn entails the investigation into how inflammation would affect the proliferation as well as the migration dynamics of gingival mesenchymal stem/progenitor cells. Materials and Methods. Clones of human gingival mesenchymal stem/progenitor cells (GMSCs) from inflamed gingival tissues were characterized for stem/progenitor cells' characteristics and compared to clones of healthy human GMSCs (n = 3), to be subsequently seeded on perforated collagen-coated poly-tetra-floro-ethylene (PTFE) membranes with a pore size 0.4 and 3 microns and polycarbonic acid membranes of 8 microns pore size in Transwell systems. The population doubling time and the MTT test of both populations were determined. Fetal bovine serum (FBS) was used as a chemoattractant in the culturing systems, and both groups were compared to their negative controls without FBS. Following 24 hours of incubation period, migrating cells were determined on the undersurface of microperforated membranes and the membrane-seeded cells were examined by scanning electron microscopy.

Results

GMSCs demonstrated all predefined stem/progenitor cell characteristics. GMSCs from inflamed gingival tissues showed significantly shorter population doubling times. GMSCs of inflamed and healthy tissues did not show significant differences in their migration abilities towards the chemoattractant, with no cellular migration observed in the absence of FBS. GMSCs from healthy gingival tissue migrated significantly better through larger micropores (8 microns). Scanning electron microscopic images proved the migratory activity of the cells through the membrane pores.

Conclusions

Inflammation appears to boost the proliferative abilities of GMSCs. In terms of migration through membrane pores, GMSCs from healthy as well as inflamed gingival tissues do not demonstrate a difference in their migration abilities through smaller pore sizes, whereas GMSCs from healthy gingival tissues appear to migrate significantly better through larger micropores.

Guided tissue regeneration of intrabony defects with perforated barrier membranes, simvastatin, and EDTA root surface modification: A clinical and biochemical study

BACKGROUND

Perforated barrier membranes (PBM) were suggested to enhance periodontal regeneration by allowing positive charity of wanted elements from the gingival tissue side. The present study was designed to evaluate clinically and biochemically the use of PBM combined with simvastatin (SMV) gel with and without an associated EDTA gel root surface etching as a suggested option that could improve SMV availability and clinical outcomes of PBM.

METHODS

Forty patients having moderate-to-severe chronic periodontitis with 40 intrabony defects were randomly divided into four treatment groups (10 sites each). Patients in group 1 received 1.2% SMV gel and covering the defect with occlusive membrane (OM). Patients in group 2 received 1.2% SMV gel and covering the defect with PBM. Group 3 received 24% EDTA root surface etching, 1.2% SMV gel, and defect coverage with OM (eOM). Patients in group 4 were treated as in group 3 but the defect was covered with PBM (ePBM). Clinical parameters were recorded at baseline before surgical procedures and were reassessed at 6 and 9 months after therapy. The mean concentration of SMV in gingival crevicular fluid (GCF) was estimated by reverse-phase high-performance liquid chromatography at days 1, 7, 14, 21, and 30.

RESULTS

At 6- and 9-month observation periods, groups 3 and 4 showed a statistically significant improvement in PD reduction and CAL gain compared with groups 1 and 2. Group 4 showed a statistically significant more defect fill compared with groups 1, 2, and 3 (P ≤ .05). Group 2 showed statistically significant higher defect fill compared with group 1 and group 3 (P < .05). Bone density was significantly increased with no significant difference between the four groups at 6- and 9-month observation periods. SMV-GCF concentration in group 4 showed the highest mean concentration with no significant difference than that of group 3.

CONCLUSION

The use of perforated barrier membranes in association with SMV enhances the clinical hard tissue parameters compared with occlusive ones in treating intrabony periodontal defects. Moreover, EDTA root surface treatment could enhance SMV availability in the defect area.

A bioactive collagen membrane that enhances bone regeneration

Membranes are an integral component of guided bone regeneration protocols. This pre-clinical study was aimed at enhancing the bioactivity of collagen membranes by incorporating plasmid DNA (pDNA) or chemically modified RNA (cmRNA) encoding bone morphogenetic protein-9 (BMP-9). In addition, we also endeavored to harness the regenerative potential of the periosteum by creating perforations in the membrane. Nanoplexes of polyethylenimine (PEI)-nucleic acids (PEI-pDNA or PEI-cmRNA encoding BMP-9) were incorporated into commercially obtained and perforated collagen membranes (PCM) to produce PCM-pDNA(BMP-9) or PCM-cmRNA(BMP-9). After structural characterization, the biodegradation kinetics of PCM, PCM-pDNA(BMP-9) and PCM-cmRNA(BMP-9) were assessed in simulated body fluid in vitro. Using a 24-well transwell plate system with bone marrow stromal cells (BMSCs) in the lower chamber and the PCM to be tested in the upper chamber, the in vitro bioactivity of different PCMs was evaluated by measuring various markers for osteogenesis in BMSCs. Alkaline phosphatase activity was assessed in BMSCs, after 7 and 11 days of exposure to PCM, PCM-pDNA(BMP-9), or PCM-cmRNA(BMP-9). Similarly, calcium deposition and Alizarin red staining in BMSCs were assessed after 14 days of exposure to the three different types of PCM. PCMs were then tested in vivo using the calvarial defect model in rats. After 4 weeks, animals were euthanized and bone specimens were harvested for micro-computed tomography and histological assessments. Incorporation of pDNA or cmRNA did not alter the biodegradation profile of PCMs. Alkaline phosphatase activity trended toward being higher in BMSCs exposed to PCM-cmRNA(BMP-9) or PCM-pDNA(BMP-9), when compared to BMSCs alone. Similar trends were observed when calcium deposition and alizarin red staining was evaluated. Calvarial bone defects treated with PCM-cmRNA(BMP-9) resulted in significantly higher bone volume/total volume % (BV/TV%), when compared to empty defects and trended toward being higher than defects treated with PCM-pDNA(BMP-9) and PCM alone. We demonstrate for the first time that resorbable PCM can be utilized to efficiently deliver pDNA and cmRNA of interest. The released pDNA and cmRNA encoding BMP-9 in this assessment was shown to be functional in vitro as well as in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1824-1832, 2019.

Treatment of intrabony defects with modified perforated membranes in aggressive periodontitis: a 4-year follow-up of a randomized controlled trial

OBJECTIVE

(1) To assess long-term outcomes 4 years following guided tissue regeneration (GTR) of intrabony defects in patients diagnosed with aggressive periodontitis (AgP) and (2) to identify predictors of clinical attachment level (CAL) gain and bone/graft density gain.

MATERIALS AND METHODS

In 15 patients, two deep intrabony defects were randomly treated with xenogenic graft plus modified perforated membranes (MPM, tests) or xenogenic graft plus standard collagen membranes (CM, controls). After 4 years, clinical and radiographic outcomes were evaluated and compared with outcomes at baseline and after 1 year.

RESULTS

After 4 years, 14 test sites and 13 control sites were available for analysis. One tooth was lost as a result of root fracture. There were significant improvements in all evaluated parameters after 1 and 4 years in relation to baseline, but no differences were observed between tests and controls. However, some non-significant changes were found between 1 and 4 years. Regression analyses showed that recurrence of periodontitis was a significant predictor for CAL gain (p = 0.001) and bone/graft density gain (p = 0.024) from 1 to 4 years.

CONCLUSIONS

GTR of intrabony defects in AgP with either standard or modified CM yielded similarly successful and maintainable clinical benefits for compromised teeth 4 years following the surgery. The use of MPM showed no additional benefit.

CLINICAL RELEVANCE

This study demonstrates that most of the positive outcomes of GTR in AgP may be preserved over 4 years. Periodontitis recurrence might influence long-term outcomes.

Thermal annealed silk fibroin membranes for periodontal guided tissue regeneration

Guided tissue regeneration (GTR) is a surgical procedure applied in the reconstruction of periodontal defects, where an occlusive membrane is used to prevent the fast-growing connective tissue from migrating into the defect. In this work, silk fibroin (SF) membranes were developed for periodontal guided tissue regeneration. Solutions of SF with glycerol (GLY) or polyvinyl alcohol (PVA) where prepared at several weight ratios up to 30%, followed by solvent casting and thermal annealing at 85 °C for periods of 6 and 12 h to produce high flexible and stable membranes. These were characterized in terms of their morphology, physical integrity, chemical structure, mechanical and thermal properties, swelling capability and in vitro degradation behavior. The developed blended membranes exhibited high ductility, which is particular relevant considering the need for physical handling and adaptability to the defect. Moreover, the membranes were cultured with human periodontal ligament fibroblast cells (hPDLs) up to 7 days. Also, the higher hydrophilicity and consequent in vitro proteolytic degradability of these blends was superior to pure silk fibroin membranes. In particular SF/GLY blends demonstrated to support high cell adhesion and viability with an adequate hPDLs' morphology, make them excellent candidates for applications in periodontal regeneration.

Treatment of intrabony defects with modified perforated membranes in aggressive periodontitis: subtraction radiography outcomes, prognostic variables, and patient morbidity

Objectives

The main objectives of this study were (1) to evaluate bone/graft density alterations by digital subtraction radiography; (2) to determine factors associated with favorable clinical and radiographic outcomes, and (3) to report on patient morbidity after guided tissue regeneration (GTR) in aggressive periodontitis (AgP) patients.

Materials and methods

Adapting a split-mouth design, 30 comparative intrabony defects in 15 patients were randomly treated with xenogenic graft plus modified perforated membranes (MPM, tests) or xenogenic graft plus standard collagen membranes (CM, controls). The time period of observation was 12 months.

Results

There were significant improvements in clinical and radiographic parameters within each group, without intergroup differences. However, higher PPD reduction for three-wall defects was noted in MPM sites (5.22 versus 3.62 mm; p = 0.033). Moreover, a significant gain in bone/graft density of 4.9% from 6 to 12 months post-operatively was observed in test sites. Multivariate analysis demonstrated that morphology of intrabony defects was a predictor of CAL gain (p = 0.06), while independent prognostic variables effecting changes in bone/graft density were radiographic defect depth (p = 0.025) and radiographic angle (p = 0.033). The majority of patients reported some discomfort, pain, and edema with mild intensity without any significant differences between treatment modalities.

Conclusions

This study demonstrated enhanced bone/graft density gain after GTR with MPM, which may indicate greater area of new bone formation. Independent variables effecting treatment outcomes were intrabony defect morphology, radiographic defect depth, and radiographic angle.

Clinical relevance

This study supports the regenerative treatment of intrabony defects in AgP patients and identifies some variables with prognostic value.

Treatment of intrabony defects with modified perforated membranes in aggressive periodontitis: a 12-month randomized controlled trial

OBJECTIVE

The aim of this study was to compare the clinical and radiographic efficacy of guided tissue regeneration with a modified perforated collagen membrane (MPM) or standard collagen membrane (CM) in the treatment of intrabony defects in patients with aggressive periodontitis (AgP).

MATERIALS AND METHODS

Fifteen AgP patients were included in the study. Two single intrabony defects of at least 3 mm depth with ≥ 6 mm probing pocket depth (PPD) from each patient were randomly assigned to either xenogenic graft plus MPM (test group) or xenogenic graft plus CM (control group). PPD, clinical attachment level (CAL), and gingival recession (GR) were recorded at baseline and at 12 months. The radiographic assessments included the measurements of defect depth (DD), change in alveolar crest position (ACP), linear defect fill (LDF), and percentage defect fill (%DF).

RESULTS

After treatment, PPD, CAL, DD, and ACP values improved significantly in both groups, without statistical differences between them. However, with respect to LDF and %DF, the 12-month radiographic analysis at MPM-treated sites showed a significant improvement compared to the 6-month outcomes, that was not observed at control sites (additional LDF of 0.4 ± 0.5 mm, p = 0.010 and %DF of 6.4 ± 7.6%, p = 0.025).

CONCLUSIONS

Both strategies proved effective in the treatment of intrabony defects in patients with AgP. Nonetheless, enhanced LDF and %DF 12 months postoperatively at MPM-treated sites may stem from cellular and molecular migration from the periosteum and overlying gingival connective tissue through barrier's pores.

CLINICAL RELEVANCE

Modification of CM may have positive ramifications on periodontal regeneration.

Regenerative Medicine for Periodontal and Peri-implant Diseases

The balance between bone resorption and bone formation is vital for maintenance and regeneration of alveolar bone and supporting structures around teeth and dental implants. Tissue regeneration in the oral cavity is regulated by multiple cell types, signaling mechanisms, and matrix interactions. A goal for periodontal tissue engineering/regenerative medicine is to restore oral soft and hard tissues through cell, scaffold, and/or signaling approaches to functional and aesthetic oral tissues. Bony defects in the oral cavity can vary significantly, ranging from smaller intrabony lesions resulting from periodontal or peri-implant diseases to large osseous defects that extend through the jaws as a result of trauma, tumor resection, or congenital defects. The disparity in size and location of these alveolar defects is compounded further by patient-specific and environmental factors that contribute to the challenges in periodontal regeneration, peri-implant tissue regeneration, and alveolar ridge reconstruction. Efforts have been made over the last few decades to produce reliable and predictable methods to stimulate bone regeneration in alveolar bone defects. Tissue engineering/regenerative medicine provide new avenues to enhance tissue regeneration by introducing bioactive models or constructing patient-specific substitutes. This review presents an overview of therapies (e.g., protein, gene, and cell based) and biomaterials (e.g., resorbable, nonresorbable, and 3-dimensionally printed) used for alveolar bone engineering around teeth and implants and for implant site development, with emphasis on most recent findings and future directions.

Gingival crevicular fluid vascular endothelial cell growth factor and platelet-derived growth factor-BB release profile following the use of perforated barrier membranes during treatment of intrabony defects: a randomized clinical trial

BACKGROUND AND OBJECTIVE

Perforated barrier membranes open channels between the suprabony and intrabony compartments of the defect, which could allow for more physiologic cellular interactions between different components of the periodontium during guided tissue regeneration surgery. To test this assumption, this study was designed to evaluate levels of vascular endothelial cell growth factor (VEGF) and platelet-derived growth factor (PDGF)-BB in gingival crevicular fluid during the early stages of healing of localized intrabony defects treated with perforated membranes (PMs) or non-PMs, as compared with open flap debridement.

MATERIAL AND METHODS

Thirty non-smoking patients with severe chronic periodontitis participated in this prospective, randomized and single blinded trial. Each patient contributed one interproximal defect that was randomly assigned to the PM group (n = 10), occlusive membrane (OM) group (n = 10) or open flap debridement (OFD) group (n = 10). Plaque index, gingival index, probing depth, clinical attachment level and the intrabony depth of the defect were measured at baseline and reassessed at 6 and 9 mo after therapy. Gingival crevicular fluid samples were collected on days 1, 3, 7, 14, 21 and 30 d after therapy for the changes in VEGF and PDGF-BB levels.

RESULTS

During the early stages of healing (1, 3 and 7 d), the mean VEGF and PDGF-BB concentrations at sites treated with PMs and OFD peaked with a statistically significant difference as compared with the OM-treated group. VEGF and PDGF-BB levels at sites treated with PMs and OFD were not statistically different. Growth factor levels decreased sharply in the samples obtained at days 21 and 30 with non-significant differences between the three groups. Nine months after therapy, the PM-treated group showed a statistically significant improvement in probing depth, clinical attachment level and intrabony defect compared to the OM and OFD groups.

CONCLUSIONS

Within the limits of the present study, one can conclude that PM coverage of periodontal defects is associated with initial gingival crevicular fluid growth factor upregulation that could improve the clinical outcomes of guided tissue regeneration surgery.

Porcine Dermis-Derived Collagen Membranes Induce Implantation Bed Vascularization Via Multinucleated Giant Cells: A Physiological Reaction?

In this study, the tissue reactions to 2 new porcine dermis-derived collagen membranes of different thickness were analyzed. The thicker material (Mucoderm) contained sporadically preexisting vessel skeletons and fatty islands. The thinner membrane (Collprotect) had a bilayered structure (porous and occlusive side) without any preexisting structures. These materials were implanted subcutaneously in mice to analyze the tissue reactions and potential transmembranous vascularization. Histological and histomorphometrical methodologies were performed at 4 time points (3, 10, 15, and 30 days). Both materials permitted stepwise connective tissue ingrowth into their central regions. In the Mucoderm matrix, newly built microvessels were found within the preexisting vessel and fatty island skeletons after 30 days. This vascularization was independent of the inflammation-related vascularization on both material surfaces. The Collprotect membrane underwent material disintegration by connective tissue strands in combination with vessels and multinucleated giant cells. The histomorphometric analyses revealed that the thickness of Mucoderm did not decrease significantly, while an initial significant decrease of membrane thickness in the case of Collprotect was found at day 15. The present results demonstrate that the 2 analyzed collagen membranes underwent a multinucleated giant cell-associated vascularization. Neither of the materials underwent transmembraneous vascularization. The microvessels were found within the preexisting vessel and fatty island skeletons. Additional long-term studies and clinical studies are necessary to determine how the observed foreign body giant cells affect tissue regeneration.

Periosteal thickness and cellularity in mid-diaphyseal cross-sections from human femora and tibiae of aged donors

Due to lack of access in healthy patients, the structural properties underlying the inherent regenerative power and advanced material properties of the human periosteum are not well understood. Periosteum comprises a cellular cambium layer directly apposing the outer surface of bone and an outer fibrous layer encompassed by the surrounding soft tissues. As a first step to elucidating the structural and cellular characteristics of periosteum in human bone, the current study aims to measure cambium and fibrous layer thickness as well as cambium cellularity in human femora and tibiae of aged donors. The major and minor centroidal axes (CA) serve as automated reference points in cross-sections of cadaveric mid-diaphyseal femora and tibiae. Based on the results of this study, within a given individual, the cambium layer of the major CA of the tibia is significantly thicker and more cellular than the respective layer of the femur. These significant intraindividual differences do not translate to significant interindividual differences. Further, mid-diaphyseal periosteal measures including cambium and fibrous layer thickness and cellularity do not correlate significantly with age or body mass. Finally, qualitative observations of periosteum in amputated and contralateral or proximal long bones of the lower extremity show stark changes in layer organization, thickness, and cellularity. In a translational context, these novel data, though inherently limited by availability and accessibility of human mid-diaphyseal periosteum tissue, provide important reference values for the use of periosteum in the context of facilitated healing and regeneration of tissue.

Surgical Approaches Based on Biological Objectives: GTR versus GBR Techniques

Guided tissue regenerative (GTR) therapies are performed to regenerate the previously lost tooth supporting structure, thus maintaining the aesthetics and masticatory function of the available dentition. Alveolar ridge augmentation procedures (GBR) intend to regain the alveolar bone lost following tooth extraction and/or periodontal disease. Several biomaterials and surgical approaches have been proposed. In this paper we report biomaterials and surgical techniques used for periodontal and bone regenerative procedures. Particular attention will be adopted to highlight the biological basis for the different therapeutic approaches.