GTR treatment of intrabony defects with PLA/PGA copolymer or collagen bioresorbable membranes in combination with deproteinized bovine bone (Bio-Oss)

Evaluation of PRF and PLA-PGA Membrane Along with Hydroxyapatite Crystal Collagen Fibers Bone Graft in the Treatment of Infrabony Defects

AIM

The present study was carried out to compare the effectiveness of leukocyte platelet-rich fibrin (L-PRF) membrane and polylactic acid-polyglycolic acid (PLA-PGA) membrane along with hydroxyapatite crystal collagen fibers bone graft in the treatment of human infrabony defects using cone beam computed tomography.

MATERIALS AND METHODS

A total of 28 systemically healthy patients was chosen which were found appropriate after initial therapy. Each group comprises of 14 defects, according to randomized parallel design. The group A was managed by hydroxyapatite crystal collagen fibers bone graft in conjunction with L-PRF membrane, while group B was treated by hydroxyapatite crystal collagen fibers bone graft in conjunction with PLA-PGA membrane. Clinical and radiographic measurements were recorded at baseline and 6 months postoperatively.

RESULTS

Statically significant difference was seen in mean probing pocket depth (PPD), mean R-CAL, and DD from baseline to 6 months in group A and group B but there was no statically significant difference in mean PPD reduction (0.35 ± 1.90 mm), mean R-CAL gain (0.28 ± 1.85 mm) and DD reduction (0.12 ± 1.42 mm) seen at 6 months when compared between both the groups.

CONCLUSION

At 6 months post-surgery both treatment modalities demonstrated statistically significant improvements with regards to CAL gains, PPD reduction, and reduction in radiographic defect depth.

CLINICAL SIGNIFICANCE

Platelet-rich fibrin (PRF) membrane and PLA-PGA membrane along with hydroxyapatite crystal collagen fibers bone graft are useful in the treatment of infrabony defect. Platelet-rich fibrin membrane with hydroxyapatite crystal collagen fibers bone graft have shown to be better in regeneration of bony defect as PRF membrane has growth factors which help in bone regeneration.

Physical Characteristics and Biocompatibility of 3D-Printed Polylactic-Co-Glycolic Acid Membranes Used for Guided Bone Regeneration

Bioresorbable polymeric membranes for guided bone regeneration (GBR) were fabricated using the three-dimensional printing technique. Membranes made of polylactic-co-glycolic acid (PLGA), which consist of lactic acid (LA) and glycolic acid in ratios of 10:90 (group A) and 70:30 (group B), were compared. Their physical characteristics including architecture, surface wettability, mechanical properties, and degradability were compared in vitro, and their biocompatibilities were compared in vitro and in vivo. The results demonstrated that the membranes of group B had mechanical strength and could support the proliferation of fibroblasts and osteoblasts significantly better than those of group A (p < 0.05). The degradation rate in Group B was significantly lower than that in Group A, but they significantly produced less acidic environment (p < 0.05). In vivo, the membranes of group B were compared with the commercially available collagen membranes (group C). The amount of newly formed bone of rat's calvarial defects covered with the membranes of group C was stable after week 2, whereas that of group B increased over time. At week 8, the new bone volumes in group B were greater than those in group C (p > 0.05). In conclusion, the physical and biological properties of the PLGA membrane (LA:GA, 70:30) were suitable for GBR.

Underestimated microbial infection of resorbable membranes on guided regeneration

Barrier membranes are critical in creating tissuecompartmentalization for guided tissue (GTR) and bone regeneration (GBR) therapies. More recently, resorbable membranes have been widely used for tissue and bone regeneration due to their improved properties and the dispensable re-entry surgery for membrane removal. However, in cases with membrane exposure, this may lead to microbial contamination that will compromise the integrity of the membrane, surrounding tissue, and bone regeneration, resulting in treatment failure. Although the microbial infection can negatively influence the clinical outcomes of regenerative therapy, such as GBR and GTR, there is a lack of clinical investigations in this field, especially concerning the microbial colonization of different types of membranes. Importantly, a deeper understanding of the mechanisms of biofilm growth and composition and pathogenesis on exposed membranes is still missing, explaining the mechanisms by which bone regeneration is reduced during membrane exposure. This scoping review comprehensively screened and discussed the current in vivo evidence and possible new perspectives on the microbial contamination of resorbable membranes. Results from eligible in vivo studies suggested that different bacterial species colonized exposed membranes according to their composition (collagen, expanded polytetrafluoroethylene (non-resorbable), and polylactic acid), but in all cases, it negatively affected the attachment level and amount of bone gain. However, limited models and techniques have evaluated the newly developed materials, and evidence is scarce. Finally, new approaches to enhance the antimicrobial effect should consider changing the membrane surface or incorporating long-term released antimicrobials in an effort to achieve better clinical success.

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.

Comparative evaluation of coronally advanced flap with and without Biomesh® membrane for the treatment of localized gingival recession defects - a clinical study

Numerous surgical procedures are used to correct gingival recession, like free gingival graft, pedicle graft, and connective tissue graft. Our study aimed to compare and clinically evaluate root coverage using a coronally advanced flap (CAF) with and without Biomesh^® membrane to treat recession type 1 (RT₁) and type 2 (RT₂) defects. A total of 20 systemically stable patients, both males and females between the ages of 20 and 40, with bilateral recession defects in maxillary canines and premolars, were included in the study. Patients were divided into two groups: the control group: coronally advanced flap only and the test group: coronally advanced flap with Biomesh^® membrane. All clinical parameters showed significant reductions from baseline, 1 month, 3 months, and 6 months post-surgery. Gingival recession significantly reduced both in test and control groups with no intergroup difference. The exposed root was covered by 70% in the test group and 78% in the control group. Clinical attachment level, the width of keratinized tissue, recession height, and recession width was significantly increased in the case of coronally advanced flap alone with significant intragroup comparison. The results for both treatment techniques for recession coverage were compared. CAF displayed superior results than CAF along with Biomesh^® membrane in terms of clinical attachment level, root coverage percentage, and attached gingiva width.

Polymer-Based Bone Substitutes in Periodontal Infrabony Defects: A Systematic Evaluation of Clinical Studies

Background and Objectives: The aim was to systematically review the available literature regarding the use of polymers as a bone substitute for the treatment of periodontal infrabony defect. Materials and methods: Three databases (PubMed, Scopus and Web of Science) were searched to find all relevant studies published in English from inception until September 2021 using a combination of keywords. The inclusion criteria consisted of human clinical studies which reported the use of a polymer-based bone substitute in the treatment of infrabony defects. Results: 164 studies were provided from the databases. Of these, five articles were eligible and reported favorable outcome in terms of probing depth, clinical attachment gain and defect fill at the follow-up (3 months and 6 months). Conclusions: Polymer based-bone substitutes may represent a useful alternative in treating infrabony defects. Due to the limited number of studies, more research is needed to sustain the advantages of these products.

Effect of systemic antibiotics on the outcomes of regenerative periodontal surgery in intrabony defects: a randomized, controlled, clinical study

OBJECTIVES

To assess the potential influence of systemic antibiotic administration on the healing of periodontal intrabony defects treated with deproteinized bovine bone mineral (DBBM) and collagen membrane.

MATERIALS AND METHODS

Forty-one intrabony defects were treated by means of DBBM and collagen membrane (GTR). Postoperatively, the patients received either systemic antibiotics (i.e., 1 g of amoxicillin, twice daily for 7 days) (test) or no antibiotics (control). Clinical attachment level (CAL), probing depth (PD), and gingival recession (GR) were measured at baseline and at 1 year following regenerative surgery. The depth of the intrabony component (INTRA DD) and its width (INTRA DW) were measured during surgery and after 1 year at reentry. The depth (RxD) and width (RxW) of the intrabony defects were evaluated radiographically at baseline and at 1 year.

RESULTS

No adverse events were observed in any of the two groups throughout the entire study period. In the test group, mean CAL changed from 8.7 ± 1.4 mm at baseline to 5.0 ± 1.7 mm at 1 year (p < 0.0001), while PD decreased from 7.8 ± 1.5 mm at baseline to 4.0 ± 0.9 mm at 1 year (p < 0.0001). In the control group, mean CAL changed from 8.6 ± 1.9 mm to 5.9 ± 1.6 mm (p < 0.001) and mean PD improved from 7.4 ± 1.3 mm to 4.1 ± 1.3 mm (p < 0.001). Mean CAL gain measured 3.6 ± 1.6 mm in the test and 2.7 ± 1.6 mm in the control group, respectively. Defect fill (i.e., INTRA DD gain) at re-entry measured 3.7 ± 1.8 mm in the test and 2.7 ± 2.1 mm in the control group. A CAL gain of ≥ 3 mm was measured in 76% of the defects in the test group and in 40% of the defects in the control group, respectively. In both groups, all evaluated clinical and radiographic parameters improved statistically significantly compared with baseline, but no statistically significant differences were found between the two groups.

CONCLUSIONS

Within their limits, the present study has failed to show any substantial added clinical benefits following the postoperative administration of amoxicillin in conjunction with regenerative periodontal surgery using DBBM and GTR.

CLINICAL RELEVANCE

The post-surgically administration of systemic antibiotics does not seem to be necessary following regenerative periodontal surgery.

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.

Clinical Evaluation of Insulin like Growth Factor-I and Vascular Endothelial Growth Factor with Alloplastic Bone Graft Material in the Management of Human Two Wall Intra-Osseous Defects

INTRODUCTION

In recent years, emphasis on the use of growth factors for periodontal healing is gaining great momentum. Several growth factors showed promising results in periodontal regeneration.

AIM

This study was designed to compare the clinical outcomes of 0.8μg recombinant human Vascular Endothelial Growth Factor (rh-VEGF) and 10μg recombinant human Insulin Like Growth Factor-I (rh-IGF-I) with β-Tricalcium Phosphate (β-TCP) and Polylactide-Polyglycolide Acid (PLGA) membrane in two wall intra-osseous defects.

MATERIALS AND METHODS

A total of 29 intra-osseous defects in 27 subjects were randomly divided into 3 test and 1 control group. Test group I (n=8) received rh-VEGF+ rh-IGF-I, Test group II (n=7) rh-VEGF, Test group III (n=7) rh-IGF-I and control group (n=7) with no growth factor, β-TCP and PLGA membrane was used in all the groups. Baseline soft tissue parameters including Probing Pocket Depth (PPD), Clinical Attachment Level (CAL), and Gingival Recession (GR) at selected sites were recorded at baseline and at 6 months. Intrasurgically, intra-osseous component was calculated as a) Cemento-Enamel Junction to Bone Crest (CEJ to BC), b) Bone Crest to Base of the Defect (BC to BD) at baseline and at re-entry. The mean changes at baseline and after 6 months within each group were compared using Wilcoxon Signed Rank Test. The mean changes for each parameter between groups were compared using Mann-Whitney U test.

RESULTS

After 6 months, maximum mean PPD reduction occurred in test group I followed by test group II, III and control group. Similar trend was observed in CAL gain. Non-significant GR was present in test group I and control group whereas in test group II and III GR was absent. The use of rh-VEGF+ rhIGF-I exhibited 95.8% osseous fill as compared to 54.8% in test group II, 52.7% in test group III and 41.1 % in the control group.

CONCLUSION

Within the limitations of this study, it can be concluded that, rh-IGF-I+rh-VEGF treated sites resulted in greater improvement in PPD reduction, CAL gain as well as in osseous fill after 6 months when compared with rh-VEGF, rh-IGF-I and control sites.

Current Uses of Poly(lactic-co-glycolic acid) in the Dental Field: A Comprehensive Review

Poly(lactic-co-glycolic acid) or PLGA is a biodegradable polymer used in a wide range of medical applications. Specifically PLGA materials are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA membranes have been studied with promising results, either alone or combined with other materials in bone healing procedures. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence that the development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in the dental field.

Biocompatibility and cytotoxic evaluation of drug-loaded biodegradable guided tissue regeneration membranes

BACKGROUND

In periodontology, Guided Tissue Regeneration (GTR) is based on the concept of providing a space for entry of cells with regenerative potential into the wound environment to initiate the regeneration of structures lost due to periodontal disease. First generation GTR membranes were primarily non-absorbable membranes like expanded polytetrafluorethylene which required a second surgery for its removal. This led researchers to explore absorbable materials like collagen and synthetic biodegradable polymers to fabricate GTR membranes. In the present study, biodegradable Polylactic acid (PLA) is used to fabricate membranes with the potential to be used for GTR therapy.

MATERIALS AND METHODS

Biocompatibility of the PLA membranes were evaluated in a subcutaneous guinea pig model. Antimicrobial effect of the drug-loaded PLA membranes were assessed against a drug-resistant Staphylococcus aureus bacterial isolate. The cytocompatibility of the drug-loaded membranes were evaluated using HeLa cell lines.

RESULTS

The PLA membranes were shown to be biocompatible. The drug-loaded PLA membranes showed significant activity against the bacterial isolate. Among the drug-loaded membranes, tetracycline-loaded membrane showed minimal cellular toxicity.

CONCLUSION

The results of this study indicate that biodegradable drug-releasing polylactide membranes have the potential to be used for periodontal regeneration. It has the necessary characteristics of a GTR membrane like biocompatibility, space maintaining ability, and tissue integration. Among the various antimicrobial agents loaded in the PLA membranes, tetracycline-loaded membranes exhibited minimal cellular toxicity against HeLa cells; at the same time showing significant activity against a pathogenic bacterium.

Chitosan/bioactive glass nanoparticle composite membranes for periodontal regeneration

Barrier membranes are used in periodontal applications with the aim of supporting periodontal regeneration by physically blocking migration of epithelial cells. The present work proposes a combination of chitosan (CHT) with bioactive glass nanoparticles (BG-NPs) in order to produce a novel guided tissue and bone regeneration membrane, fabricated by solvent casting. The CHT/BG-NP nanocomposite membranes are characterized in terms of water uptake, in mechanical tests, under simulated physiological conditions and in in vitro bioactivity tests. The addition of BG-NPs to CHT membranes decreased the mechanical potential of these membranes, but on the other hand the bioactivity improved. The membranes containing the BG-NPs induced the precipitation of bone-like apatite in simulated body fluid (SBF). Biological tests were carried out using human periodontal ligament cells and human bone marrow stromal cells. CHT/BG-NP composite membranes promoted cell metabolic activity and mineralization. The results indicate that the CHT/BG-NP composite membrane could potentially be used as a temporary guided tissue regeneration membrane in periodontal regeneration, with the possibility to induce bone regeneration.

Advanced reconstructive technologies for periodontal tissue repair

Reconstructive therapies to promote the regeneration of lost periodontal support have been investigated through both preclinical and clinical studies. Advanced regenerative technologies using new barrier-membrane techniques, cell-growth-stimulating proteins or gene-delivery applications have entered the clinical arena. Wound-healing approaches using growth factors to target the restoration of tooth-supporting bone, periodontal ligament and cementum are shown to significantly advance the field of periodontal-regenerative medicine. Topical delivery of growth factors, such as platelet-derived growth factor, fibroblast growth factor or bone morphogenetic proteins, to periodontal wounds has demonstrated promising results. Future directions in the delivery of growth factors or other signaling models involve the development of innovative scaffolding matrices, cell therapy and gene transfer, and these issues are discussed in this paper.

An evaluation of a resorbable (semirigid) GTR membrane in human periodontal intraosseous defects: A clinicoradiological re-entry study

AIM

To evaluate the effectiveness of a resorbable, semi rigid guided tissue regeneration (GTR) membrane in the treatment of periodontal intraosseous defects.

SETTINGS AND DESIGN

Randomized controlled clinicoradiological re-entry study.

MATERIALS AND METHODS

Eight patients with bilateral, identical intraosseous defects were selected. The sides for test and control group were randomly allocated to treat either with bioresorbable semi rigid membrane (test group) or open flap debridement (control group). Radiographic analysis was done by comparing intraoral peri apical radiographs taken at baseline and at six months. Extended cone paralleling device with grid was used to standardize radiographs. Auto CAD software was used for the analysis.

STATISTICAL ANALYSIS USED

Paired-t test.

RESULTS

On surgical reentry at six months, the mean reduction in depth of the defect at the test site was 2.63 mm. The mean gain in Relative attachment level was 1.75 mm. The control sites showed a statistically insignificant gain. The mean percentage defect fill assessed on radiographs using auto CAD software was 15.54%.

CONCLUSION

The resorbable, semi-rigid GTR membrane can be effectively used for the treatment of human one-walled angular defects.

Osteoanagenesis after transplantation of bone marrow-derived mesenchymal stem cells using polyvinylidene chloride film as a scaffold

The aim of this study was to develop a new cell transplantation technique for osteoanagenesis at bone defect sites. Polyvinylidene chloride (PVDC) film was evaluated because of its good biocompatibility and flexibility. We used this film as both a cell scaffold and a barrier membrane. Initially, the cell compatibility of the PVDC film for fibroblast-like cells and osteoblast-like cells was confirmed. Subsequently, bone marrow cells were obtained from rats and cultured on PVDC films in two kinds of medium. The PVDC films with bone marrow-derived mesenchymal stem cells (MSCs) were then applied to critical-sized bone defects in the calvarial bone of rats. After the transplantation, the surgical sites were dissected out and evaluated by soft X-ray radiography, micro-CT analysis and histological examinations. The bone marrow-derived MSC-transplanted rats showed greater bone regeneration than the control rats. Therefore, PVDC film is considered to be useful as a scaffold for bone regeneration.

The Application of Microencapsulation Techniques in the Treatment of Endodontic and Periodontal Diseases

In the treatment of intracanal and periodontal infections, the local application of antibiotics and other therapeutic agents in the root canal or in periodontal pockets may be a promising approach to achieve sustained drug release, high antimicrobial activity and low systemic side effects. Microparticles made from biodegradable polymers have been reported to be an effective means of delivering antibacterial drugs in endodontic and periodontal therapy. The aim of this review article is to assess recent therapeutic strategies in which biocompatible microparticles are used for effective management of periodontal and endodontic diseases. In vitro and in vivo studies that have investigated the biocompatibility or efficacy of certain microparticle formulations and devices are presented. Future directions in the application of microencapsulation techniques in endodontic and periodontal therapies are discussed.

Long-term stability of adipose tissue generated from a vascularized pedicled fat flap inside a chamber

BACKGROUND

Numerous studies demonstrate the generation and short-term survival of adipose tissue; however, long-term persistence remains elusive. This study evaluates long-term survival and transferability of de novo adipose constructs based on a ligated vascular pedicle and tissue engineering chamber combination.

METHODS

Defined adipose tissue flaps were implanted into rats in either intact or perforated domed chambers. In half of the groups, the chambers were removed after 10 weeks and the constructs transferred on their vascular pedicle to a new site, where they were observed for a further 10 weeks. In the remaining groups, the tissue construct was observed for 20 weeks inside the chamber. Tissue volume was assessed using magnetic resonance imaging and histologic measures, and constructs were assessed for stability and necrosis. Sections were assessed histologically and for proliferation using Ki-67.

RESULTS

At 20 weeks, volume analysis revealed an increase in adipose volume from 0.04 ± 0.001 ml at the time of insertion into the chambers to 0.27 ± 0.004 ml in the closed and 0.44 ± 0.014 ml in the perforated chambers. There was an additional increase of approximately 10 to 15 percent in tissue volume in flaps that remained in chambers for 20 weeks, whereas the volume of the transferred tissue not in chambers remained unaltered. Histomorphometric assessment of the tissues documented no signs of hypertrophy, fat necrosis, or atypical changes of the newly generated tissue.

CONCLUSION

This study presents a promising new method of generating significant amounts of mature, vascularized, stable, and transferable adipose tissue for permanent autologous soft-tissue replacement.

Periodontal regeneration: a challenge for the tissue engineer?

Periodontitis affects around 15 per cent of human adult populations. While periodontal treatment aimed at removing the bacterial cause of the disease is generally very successful, the ability predictably to regenerate the damaged tissues remains a major unmet objective for new treatment strategies. Existing treatments include the use of space-maintaining barrier membranes (guided tissue regeneration), use of graft materials, and application of bioactive molecules to induce regeneration, but their overall effects are relatively modest and restricted in application. The periodontal ligament is rich in mesenchymal stem cells, and the understanding of the signalling molecules that may regulate their differentation has increased enormously in recent years. Applying these principles for the development of new tissue engineering strategies for periodontal regeneration will require further work to determine the efficacy of current experimental preclinical treatments, including pharmacological application of growth factors such as bone morphogenetic proteins (BMPs) or Wnts, use of autologous stem cell reimplantation strategies, and development of improved biomaterial scaffolds. This article describes the background to this problem, addresses the current status of periodontal regeneration, including the background biology, and discusses the potential for some of these experimental therapies to achieve the goal of clinically predictable periodontal regeneration.

Clinical and histologic evaluation of a granular bovine bone biomaterial used as an adjunct to GTR with a bioresorbable bovine pericardium collagen membrane in the treatment of intrabony defects

BACKGROUND

The aim of the present study is to evaluate the clinical and histologic healing of deep intrabony defects treated with guided tissue regeneration (GTR) with a collagen membrane from bovine pericardium and implantation of granular bovine bone biomaterial.

METHODS

Thirty patients with one deep, combined 1- and 2-wall intrabony defect exhibiting a probing depth ≥6 mm and an associated intrabony defect ≥3 mm were treated with GTR with a bioresorbable collagen membrane from bovine pericardium and adjunct implantation of a granular bovine bone biomaterial. The clinical results were evaluated 1 and 3 years after surgery. In addition, five teeth fulfilling the inclusion criteria but scheduled for extraction because of advanced periodontitis or restorative considerations were treated similarly and then extracted along with a portion of their surrounding periodontal tissues for histologic evaluation 6 months after surgery.

RESULTS

Healing was uneventful in all patients. Significant clinical improvements were observed at 1 and 3 years postoperatively (P <0.01; probing depth averaged 4.4 ± 1.6 and 4.7 ± 1.4 mm and clinical attachment level gain was 3.9 ± 1.4 and 3.5 ± 1.3 mm, respectively). The histologic evaluation revealed formation of new cellular cementum and new periodontal ligament in four of the five cases. In general, the xenograft particles seemed to be mostly embedded in connective tissue without any evidence of new bone formation.

CONCLUSION

GTR treatment of intrabony defects with the collagen membrane from bovine pericardium and adjunct implantation of the new bovine bone biomaterial may result in significant clinical improvements that can be maintained over a period of 3 years, and regeneration of cementum and periodontal ligament, but without bone formation.

Use of bovine hydroxyapatite with or without biomembrane in sinus lift in rabbits: histopathologic analysis and immune expression of core binding factor 1 and vascular endothelium growth factor

PURPOSE

Considering the clinical discussion on the necessity of using a barrier membrane in the osteotomy area of sinus lift procedures to prevent fibrous tissue formation in this area and as a physical limit, the aim of this study was to analyze and compare the use of bovine hydroxyapatite (HA) with and without a biologic membrane by histopathologic analysis and immune expression of core binding factor 1 and vascular endothelium growth factor in the sinus lift in rabbits.

MATERIALS AND METHODS

Sixteen male rabbits underwent bilateral sinus lift procedures and were divided into 2 groups according to the sinus filling material: group 1 received bovine HA (Bio-Oss; Geistlich Pharma AG, Wohlhusen, Switzerland) and group 2 received bovine HA and a nonporous polytetrafluorethylene membrane. All groups were sacrificed after 7, 14, 30, and 60 days for microscopic, histomorphometric, and immunohistochemical analyses.

RESULTS

Microscopic analysis showed a similar bone repair pattern between the tested groups. New bone formation, soft tissue, and the remaining material were analyzed by histomorphometric analysis. No statistically significant differences (P > .05) were detected between groups for all periods analyzed. In addition, no remarkable differences were noticed in core binding factor 1 or vascular endothelium growth factor immune expression.

CONCLUSION

Taken together, these results show that using a biologic membrane does not improve bone repair induced by bovine HA, as shown by histopathologic and immunohistochemical analyses.

A new method for inducing bone tissue regeneration: negative pressure membrane technology

With the advances of medical molecular biology in recent years, our understanding of the process of fracture healing has deepened and the development of new technologies for guided bone regeneration has emerged. Here, with the recent discoveries of membrane-based as well as negative pressure-induced tissue regeneration, we suggest an innovative method of bone regeneration using negative pressure membrane technology. Polymeric membrane materials are implanted around the fracture site using in vitro devices. The container of the membrane between the fracture ends can induce effective negative pressure in order to attain both membrane and negative pressure-induced bone regeneration. The key to this technology is the use of semi-permeable membranes, which prevent the collapse of membranous structures and the loss of a variety of bone marrow cells and larger proteins during the induction of negative pressure.

Histological analysis of induced cartilage on the biodegradable or nonbiodegradable membranes from immature muscular tissue in vitro

Successful tissue engineering relies on a combination of cells, cytokines, and appropriate scaffolds. Here, we tried to induce the formation of cartilage in vitro using immature muscular tissue, crude bone morphogenetic protein (BMP) as a source of the cytokine, and biodegradable membranes (BioMend; BM and GC-membrane; GC-M) or a nonbiodegradable membrane (GORE-TEX; GT) as scaffolds. Crude BMP was extracted from bovine cortical bones, dried, and dissolved in 1M urea before it was added to immature muscular tissue from the forelimbs of fetal Sprague Dawley rats at 20 days of pregnancy. The tissue was then cultured for 2 weeks in a carbon dioxide incubator. Complete cartilage was observed only when GT was used as a scaffold. In addition, cartilage-like tissue formation was observed when BM was used, and partial cartilage formation was observed for GC-M. Therefore, these results show that immature muscular tissue differentiated into cartilage and GORE-TEX is the most effective material for use as a scaffold in this model of tissue engineering.

Surgical guided tissue regeneration treatment of advanced periodontal defects: a 5-year follow-up study

OBJECTIVES

To study the 5-year outcome of combined use of guided tissue regeneration (GTR) barriers and bovine bone in advanced periodontal defects.

MATERIAL AND METHODS

In each of 24 patients, one defect was surgically exposed, debrided, filled with bovine bone, and covered with a bioresorbable barrier. Re-examinations were made after 1, 3, and 5 years.

RESULTS

Average full-mouth plaque scores (FMPS) were 14.5% at baseline and 10.7%, 9.8%, and 18.9% after 1, 3, and 5 years, respectively. Mean probing pocket depth (PPD) was 10.0 mm at baseline. Mean PPD reduction was 5.2 mm after 1 year, 5.6 mm after 3 years, and 5.3 mm after 5 years. Mean gingival recession was 1.0 mm after 1 year, 1.6 mm after 3 years, and 1.3 mm after 5 years. Mean gain in clinical attachment level (CAL) was 4.2 mm at the 1-year, 4.1 mm at the 3-year, and 4.3 mm at the 5-year examination. Smoking significantly influenced CAL change at all re-examinations. FMPS were significantly correlated with radiographic defect depth at the 5-year examination and CAL with smoking and FMPS at the 3-year examination.

CONCLUSION

Advanced periodontal defects can be successfully treated with the combined use of GTR barriers and bovine bone to substantially reduce PPD and achieve a stable, long-term gain of CAL.

Matrices and scaffolds for drug delivery in dental, oral and craniofacial tissue engineering

Current treatments for diseases and trauma of dental, oral and craniofacial (DOC) structures rely on durable materials such as amalgam and synthetic materials, or autologous tissue grafts. A paradigm shift has taken place to utilize tissue engineering and drug delivery approaches towards the regeneration of these structures. Several prototypes of DOC structures have been regenerated such as temporomandibular joint (TMJ) condyle, cranial sutures, tooth structures and periodontium components. However, many challenges remain when taking in consideration the high demand for esthetics of DOC structures, the complex environment and yet minimal scar formation in the oral cavity, and the need for accommodating multiple tissue phenotypes. This review highlights recent advances in the regeneration of DOC structures, including the tooth, periodontium, TMJ, cranial sutures and implant dentistry, with specific emphasis on controlled release of signaling cues for stem cells, biomaterial matrices and scaffolds, and integrated tissue engineering approaches.

Comparison of the proliferative activity in gingival epithelium after surgical treatments of intrabony defects with bioactive glass and bioabsorbable membrane

Guided tissue regeneration is based on preventing the more rapidly proliferating epithelium from growing into the periodontal defect after surgical procedures incorporating barrier membranes. The aim of this study was to compare the proliferative activity of gingival epithelium using proliferating cell nuclear antigen (PCNA) as a marker of cell proliferation after surgical treatments with bioactive glass graft material and bioabsorbable membrane. Using split mouth design, 20 intrabony defects were randomly assigned treatments with bioactive glass (BG group) or bioabsorbable membrane (BM group). Gingival biopsies were taken at preoperative and postoperative 12 weeks. After histological processing, the number of the inflammatory cells was measured in hematoxylin and eosin-stained sections; PCNA expression was determined in immunohistochemically-stained sections. At postoperative 12 weeks, the number of the inflammatory cells was significantly decreased (p < 0.01), PCNA expression was significantly increased (p < 0.001) in both treatment groups compared to baseline data. There was no significant difference in PCNA expression between baseline values of two groups (p > 0.05), while at postoperative 12 weeks, increase in BG group was significantly greater than that in BM group (p < 0.001). These results suggest that epithelial cell proliferation is more prominent after treatment of intrabony defects with bioactive glass compared to the treatment with bioabsorbable membrane.

Implantation of a scaffold following bulbectomy induces laminar organization of regenerating olfactory axons

Primary olfactory axons expressing different odorant receptors are interspersed within the olfactory nerve. However, upon reaching the outer nerve fiber layer of the olfactory bulb they defasciculate, sort out, and refasciculate prior to targeting glomeruli in fixed topographic positions. While odorant receptors are crucial for the final targeting of axons to glomeruli, it is unclear what directs the formation of the nerve fiber and glomerular layers of the olfactory bulb. While the olfactory bulb itself may provide instructive cues for the development of these layers, it is also possible that the incoming axons may simply require the presence of a physical scaffold to establish the outer laminar cytoarchitecture. In order to begin to understand the underlying role of the olfactory bulb in development of the outer layers of the olfactory bulb, we physically ablated the olfactory bulbs in OMP-IRES-LacZ and P2-IRES-tau-LacZ neonatal mice and replaced them with artificial biological scaffolds molded into the shape of an olfactory bulb. Regenerating axons projected around the edge of the cranial cavity at the periphery of the artificial scaffold and were able to form an olfactory nerve fiber layer and, to some extent, a glomerular layer. Our results reveal that olfactory axons are able to form rudimentary cytoarchitectonic layers if they are provided with an appropriately shaped biological scaffold. Thus, the olfactory bulb does not appear to provide any tropic substance that either attracts regenerating olfactory axons into the cranial cavity or induces these axons to form a plexus around its outer surface.

Gene therapeutics for periodontal regenerative medicine

There has been significant advancement in the field of periodontal tissue engineering over the past decade for the repair of tooth-supporting structures. Although encouraging results for periodontal tissue regeneration have been found in numerous clinical investigations using recombinant growth factors, limitations exist with topical protein delivery. Newer approaches seek to develop methodologies that optimize growth factor targeting to maximize the therapeutic outcome of periodontal regenerative procedures. Genetic approaches in periodontal tissue engineering show early progress in achieving delivery of growth factor genes, such as platelet-derived growth factor or bone morphogenetic protein, to periodontal lesions. Ongoing investigations in ex vivo and in vivo gene transfer to periodontia seek to examine the extent of the potential effects in stimulating periodontal tissue engineering.