Devices for periodontal regeneration

Guided Bone Regeneration Using Barrier Membrane in Dental Applications

Guided bone regeneration (GBR) is a widely used technique in preclinical and clinical studies due to its predictability. Its main purpose is to prevent the migration of soft tissue into the osseous wound space, while allowing osseous cells to migrate to the site. GBR is classified into two main categories: resorbable and non-resorbable membranes. Resorbable membranes do not require a second surgery but tend to have a short resorption period. Conversely, non-resorbable membranes maintain their mechanical strength and prevent collapse. However, they require removal and are susceptible to membrane exposure. GBR is often used with bone substitute graft materials to fill the defect space and protect the bone graft. The membrane can also undergo various modifications, such as surface modification and biological factor loading, to improve barrier functions and bone regeneration. In addition, bone regeneration is largely related to osteoimmunology, a new field that focuses on the interactions between bone and the immune system. Understanding these interactions can help in developing new treatments for bone diseases and injuries. Overall, GBR has the potential to be a powerful tool in promoting bone regeneration. Further research in this area could lead to advancements in the field of bone healing. This review will highlight resorbable and non-resorbable membranes with cellular responses during bone regeneration, provide insights into immunological response during bone remodeling, and discuss antibacterial features.

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.

In Vitro Evaluation of the Permeability of Different Resorbable Xenogeneic Membranes after Collagenolytic Degradation

In this in vitro study, we compare the penetration of cells through different resorbable collagen membranes, which were collagenolytically degraded over different time periods. Three different resorbable collagen membranes were evaluated, including two non-cross-linked (NCL) membranes-namely, a porcine (NCL-P) and an equine (NCL-E) membrane-and an enzymatically cross-linked porcine (ECL-B) membrane. A special two-chamber model was fabricated, allowing for the placement of separating membranes, and a non-porous polyester membrane was used as a negative control (C), in order to verify the impermeability of the experimental chamber device. Round membrane samples with a diameter of 16 mm were fabricated. Eighteen membranes of each type were punched and placed on polyethylene nets as carriers. The membranes were then biodegraded-each on its carrier-in 12-well polystyrene plates: three samples of each membrane type were degraded for 1.5, 3, 6, or 12 h in 2 mL of a buffered collagenase solution, at 37 °C. For control purposes, three samples of each membrane type were not degraded, but only immersed in buffer solution for 1.5, 3, 6, or 12 h, at 37 °C. Another three samples of each type of membrane were degraded until complete dissolution, in order to determine the full hydroxyproline content for comparison. Liquid-preserved boar semen (containing at least 120 million sperm cells per milliliter) was used to test the cell occlusivity of the degraded membranes. At baseline and initial degradation, all tested membranes were tight, and no penetration was observed with up to 30 min of incubation time (results not shown). After 1.5 h, cells were partially capable of penetrating the NCL-E membrane only. One sample showed leakage, with a sperm volume of 1.7 million cells/mL over all samples. No penetration occurred in the test, NCL-P, and ECL-B groups. After a degradation time of 3 h, the NCL-P and ECL-B membranes remained occlusive to cells. All the membranes and measurements indicated leakage in the NCL-E group. After 6 h, four NCL-P measurements showed the first signs of cell penetration, as boar spermatozoa were detectable in the lower chamber (64 million cells/mL). The ECL-B membranes remained completely cell occlusive. After 12 h, four NCL-P measurements were cell penetration positive (14.6 million cells/mL), while the ECL-B group remained tight and showed no cell penetration. As the findings of our study are well in accordance with the results of several previous animal studies, it can be concluded that the surrogate model is capable of performing rapid and cheap screening of cell occlusivity for different collagen membranes in a very standardized manner. In particular, claims of long degradation resistance can be easily proven and compared. As the boar spermatozoa used in the present report had a size of 9 × 5 μm, smaller bacteria are probably also able to penetrate the leaking membranes; in this regard, our proposed study set-up may provide valuable information, although it must be acknowledged that sperm cells show active mobility and do not only translocate by growth.

Characterization of Immunogenicity Associated with the Biocompatibility of Type I Collagen from Tilapia Fish Skin

Collagen from fish has been proven to have a low antigenicity that has no difference in the genetic codes compared with mammalian-based collagen. This study was designed to investigate the impact of tilapia skin collagen on immunogenicity and biocompatibility in vivo and in vitro. The structural characteristics of both acid-soluble and pepsin-soluble collagen (ASC and PSC), determined using SDS-PAGE and atomic force microscopy imaging experiments, revealed that the collagen had the basic characteristics of type I collagen (COL-I). The in vitro biocompatibility of the collagens showed good cell proliferation against human foreskin fibroblast (HFF-1) cells. PSC and ASC were considered to be almost non-hemolytic biomaterials with favorable blood compatibility in hemolysis tests. The in vivo antigenicity of the collagen in an ICR mouse model evoked an acceptable specific inflammatory response compared to bovine collagen. The implant’s position had developed a complete granulation tissue and the sponge disappeared after 8 weeks. The level of cytokines produced by the COL-I immune response was much lower than bovine collagen, which indicated the appropriate implantable property and biodegradability of the collagens. In conclusion, the tilapia COL-I has a lower immunogenicity with better compatibility than bovine COL-I and is a potential alternative to conventional mammalian collagens in biomedical uses.

Overview of the Effect of Different Regenerative Materials in Class II Furcation Defects in Periodontal Patients

The aim of this review was to give an overview of the outcomes of the use of different regenerative materials to treat molars with class II furcation defects in patients with periodontitis in comparison with open flap debridement (OFD). A search of five databases (PubMed-Medline, Embase, Cochrane, Scopus and Web of Science) was conducted up to and including January 2022. According to the PICOS guidelines, only randomized control trials (S) considering periodontal patients with at least one molar with a class II furcation involvement (P) treated with regenerative materials (I) in comparison to OFD as control treatment (C) and a minimum follow-up period of 6 months were included. Vertical clinical attachment level (VCAL) was considered as the primary outcome (O), while horizontal clinical attachment level (HCAL), horizontal probing depth (HPD) and vertical probing depth (VPD) were considered as secondary outcomes. The search through the databases initially identified 1315 articles. Only 25 of them met the eligibility criteria and were included. The studies were grouped in four macro-categories according to the material used: absorbable and non-absorbable membranes, blood derivatives and a combination of different materials. The greater part of the included studies reported a statistically significant difference in using regenerative materials when compared to OFD. The blood derivatives groups reported a range of mean changes in VCAL of 0.86–4.6 mm, absorbable membrane groups reported −0.6–3.75 mm, non-absorbable membranes groups reported −2.47–4.1 mm, multiple materials groups reported −1.5–4.87 mm and enamel matrix derivatives reported a mean change in VCAL of 1.45 mm. OFD showed a range of mean VCAL changes of −1.86–2.81 mm. Although no statistical analysis was performed, the use of regenerative materials may be considered moderately beneficial in the treatment of molars with grade II furcation involvement. However, the substantial heterogeneity in the protocols’ design does not allow us to draw definitive conclusions. In addition, low levels of evidence for morbidity and patient-centered outcomes were reported.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

A novel lamellar structural biomaterial and its effect on bone regeneration

To evaluate a novel lamellar structural biomaterial as a potential biomaterial for guided bone regeneration, we describe the preparation of a collagen membrane with high mechanical strength and anti-enzyme degradation ability by using the multi-level structure of Ctenopharyngodon idella scales. The physical and chemical properties, in vitro degradation, biocompatibility, and in vivo osteogenic activity were preliminarily evaluated. In conclusion, it was shown that the multi-layered collagen structure material had sufficient mechanical properties, biocompatibility, and osteogenic ability. Meanwhile, it is also shown that there is a gap in current clinical needs, between the guided tissue regeneration membrane and the one being used. Therefore, this study provides useful insights into the efforts being made to design and adjust the microstructure to balance its mechanical properties, degradation rate, and osteogenic activity.

To evaluate a novel lamellar structural biomaterial for guided bone regeneration, we describe the preparation of a collagen membrane with high mechanical strength and anti-enzyme degradation ability using Ctenopharyngodon idella scales.

Bioresorbable magnesium-reinforced PLA membrane for guided bone/tissue regeneration

Considering the inferior mechanical properties of the current bioresorbable polymers, a novel bioresorbable magnesium-reinforced polylactide (PLA) membrane was designed for the application in critical defect sites in guided bone/tissue regeneration. The PLA-FAZ91 membrane was fabricated by combining two PLA membranes with a fluoride-coated AZ91 (9 wt% Al, 1 wt% Zn) (FAZ91) magnesium alloy core by hot pressing. A combined double-layered PLA membrane was used as the control group. A three-point bending test was performed to compare their maximum load and stiffness. Samples were immersed in the HBSS for 20 weeks, and their weight loss percentages were recorded, and a three-point bending test was performed after immersion. An ion release test was performed by immersing samples in the HBSS for 4 weeks and determining the pH and ion concentrations of the HBSS. Cell viability was tested by culturing pre-osteoblast cells with sample extracts in the culture medium obtained from degraded samples. As a result, PLA-FAZ91 showed a significantly higher maximum load and stiffness than those of the non-reinforced PLA membrane. The weight loss of PLA-FAZ91 was much faster, as FAZ91 showed major degradation and was completely degraded after 16-20 weeks of immersion. The degradation of the PLA wrap was accelerated by FAZ91. The mechanical superiority of PLA-FAZ91 over PLA endured for at least 3 weeks during immersion. The pH, magnesium- and fluoride-ion concentration in the PLA-FAZ91 group increased at an appropriate rate. The cell viability was not adversely affected by the addition of FAZ91 to PLA. Therefore, the bioresorbable magnesium-reinforced PLA membrane has the potential to be used as a good alternative to pure PLA membrane in guided bone/tissue regeneration.

A pure zinc membrane with degradability and osteogenesis promotion for guided bone regeneration: In vitro and in vivo studies

Selection of an appropriate membrane material for guided bone regeneration (GBR) is still ongoing among resorbable and nonresorbable membranes with different characteristics. The major problem with nonresorbable membranes is the inevitable secondary surgery, while resorbable polymer membranes have limitations in providing sufficient mechanical support during the bone repair period due to premature loss of mechanical strength. Pure magnesium foil has been evaluated to explore its feasibility as a resorbable GBR membrane. It exhibited better mechanical properties, whereas poor formability and fast degradation rate were noted. In light of this, pure zinc membrane was developed as a pilot research in this paper. We designed three types of pure zinc membranes: pure Zn without pores, pure Zn with 300 µm diameter and 1000 µm diameter pores, and pure titanium without pores as a control. The mechanical property, in vitro immersion tests, and MC3T3-E1 cell viability assays were tested. Moreover, in vivo behaviors of three type zinc membranes were evaluated by using a rat calvarial critical-sized bone defect model. The experimental results indicated that pure Zn membrane with 300 µm pores showed the most favorable osteogenic capability, comparable to that of titanium membrane without pores. Therefore, considering appropriate degradation rate, adequate mechanical maintenance, and profitable osteogenic capacity, metallic pure zinc is believed to be a promising candidate for barrier membranes in GBR therapy for bone regeneration, and its mechanical property can be enhanced with further alloying. STATEMENT OF SIGNIFICANCE: Metallic element zinc plays a pivotal role in the growth and mineralization of bone tissues. As a pilot research, three type of guided bone regeneration (GBR) membranes were developed in the present work: pure Zn without pores, pure Zn with 300 µm-diameter and 1000 µm-diameter pores respectively. The mechanical property, in vitro immersion tests and MC3T3-E1 cell viability assays were tested, with pure titanium without pores as a control, thereafter the in vivo performance were evaluated by using a rat calvarial critical-sized bone defect model. It indicated that pure Zn membrane with 300 µm pores showed the most favorable osteogenic capability, comparable to that of titanium membrane control, and is believed to be a promising material candidate as barrier membrane in GBR therapy for bone regeneration.

Comparing Properties of Variable Pore-Sized 3D-Printed PLA Membrane with Conventional PLA Membrane for Guided Bone/Tissue Regeneration

The aim of this study was to fabricate bioresorbable polylactide (PLA) membranes by 3D printing and compare their properties to those of the membranes fabricated by the conventional method and compare the effect of different pore sizes on the properties of the 3D-printed membranes. PLA membranes with three different pore sizes (large pore-479 μm, small pore-273 μm, and no pore) were 3D printed, and membranes fabricated using the conventional solvent casting method were used as the control group. Scanning electron microscopy (SEM) and micro-computed tomography (µ-CT) were taken to observe the morphology and obtain the porosity of the four groups. A tensile test was performed to compare the tensile strength, elastic modulus, and elongation at break of the membranes. Preosteoblast cells were cultured on the membranes for 1, 3 and 7 days, followed by a WST assay and SEM, to examine the cell proliferation on different groups. As a result, the 3D-printed membranes showed superior mechanical properties to those of the solvent cast membranes, and the 3D-printed membranes exhibited different advantageous mechanical properties depending on the different pore sizes. The various fabrication methods and pore sizes did not have significantly different effects on cell growth. It is proven that 3D printing is a promising method for the fabrication of customized barrier membranes used in GBR/GTR.

Comparison of Different Bone Filling Materials and Resorbable Membranes by Means of Micro-Tomography. A Preliminary Study in Rabbits

The purpose of this work was to evaluate the behavior of different membranes and bone filling materials used to fill critical defects in rabbit calvaria. Four defects were prepared in the cranial calvaria of female rabbits. They were randomly divided into three subgroups according to the type of barrier membrane to be used. Four animals carried cross-linked bovine collagen membranes (Mem-Lok, Bio-Horizons, Birmingham, AL, USA)), four human fascia lata membranes (Tissue, Inbiomed SA, Córdoba, Argentina) and four human chorioamniotic membranes (Tissue. Inbiomed SA, Córdoba, Argentina). The defects were filled with the deproteinized bovine bone particulate Bio­Oss® (Geistlich­Pharma AG, Wolhusen, Switzerland), with particulate human hydroxyapatite MinerOss® (Bio-Horizons, Birmingham, AL, USA), with particulate dental material (Tissue Bank Foundation, Inbiomed S.A., Córdoba, Argentina), and the last one was left without the addition of filler material. In the first group of four specimens, a resorbable cross-linked bovine collagen membrane was placed over the skull and defects, without additional fixing. In the second group, a human fascia lata membrane was placed, without additional fixing. In the third group, a human chorioamniotic membrane was placed, without additional fixing. The animals were sacrificed at 4 and 8 weeks. The highest percentages of relative radiological density (average) were recorded considering the amnio-chorionic membranes (83.63%) followed by collagen (81.44%) and finally the fascia lata membranes (80.63%), but the differences were not statistically significant (p > 0.05). The sites grafted with a decellularized tooth (96.83%) and Bio­Oss (88.42%), recorded the highest percentages of radiological density but did not differ significantly from each other (subset 2). The three membranes used did not show statistical differences between them, in any of the two time periods used. There were statistical differences between the filling materials evidencing the presence of a large quantity of calcified material in the defects treated with particulate tooth and deproteinized bovine bone and while smaller amounts of calcified material were registered in the case of defects treated with human hydroxyapatite and those that were not treated.

Increasing the tissue thickness at implant sites using guided bone regeneration and an additional collagen matrix: Histologic observations in beagle dogs

OBJECTIVES

To histologically determine the alteration in horizontal mucosal thickness at sites that received guided bone regeneration (GBR) with additional use of collagen matrix and to assess whether bone formation is affected by adding collagen matrix at GBR sites at 8 weeks of healing.

MATERIALS AND METHODS

Eight weeks after bilateral extraction of maxillary premolars, standardized defects were created on buccal side of edentulous ridges in four beagle dogs. One side was randomly allocated as control (biphasic calcium phosphate plus collagen membrane; GBR only), while contralateral side was allocated as test (biphasic calcium phosphate plus collagen membrane plus an additional layer of collagen matrix). Histologic observations, histomorphometric and micro-computed tomography analyses were performed after 8 weeks.

RESULTS

Membrane complex comprising residual collagen membrane and adjacent dense connective tissue was observed at both control and test sites. The thickness in the histologic analysis were 1.69 ± 0.23 mm (control) and 1.76 ± 0.07 mm (test) in histologic analysis and were 2.03 ± 0.26 mm (control) and 2.14 ± 0.24 mm (test) in radiographic analysis. The thickness of the membrane complex in soft-tissue layer were 723.0 ± 241.6 μm (control) and 984.6 ± 334.4 μm (test). The percentage of new bone formation were 22.30 ± 5.92% (control) and 25.50 ± 8.08% (test). All measured outcome did not show significant differences between control and test groups.

CONCLUSION

The addition of collagen matrix on top of standard GBR procedure did not increase the soft tissue thickness and dense connective tissue formation at 8 weeks of healing. Bone regeneration was not affected by the addition of collagen matrix. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 741-749, 2019.

An overview of periodontal regenerative procedures for the general dental practitioner

The complete regeneration of the periodontal tissues following periodontal disease remains an unmet challenge, and has presented clinicians with a remarkably difficult clinical challenge to solve given the extensive research in this area and our current understanding of the biology of the periodontal tissues. In particular as clinicians we look for treatments that will improve the predictability of the procedure, improve the magnitude of the effect of treatment, and perhaps most importantly in the long term would extend the indications for treatment beyond the need for single enclosed bony defects to allow for suprabony regeneration, preferably with beneficial effects on the gingival soft tissues. A rapid development in both innovative methods and products for the correction of periodontal deficiencies have been reported during the last three decades. For example, guided tissue regeneration with or without the use of bone supplements has been a well-proven treatment modality for the reconstruction of bony defects prior to the tissue engineering era. Active biomaterials have been subsequently introduced to the periodontal community with supporting dental literature suggesting that certain factors should be taken into consideration when undertaking periodontal regenerative procedures. These factors as well as a number of other translational research issues will need to be addressed, and ultimately it is vital that we do not extrapolate results from pre-clinical and animal studies without conducting extensive randomized clinical trials to substantiate outcomes from these procedures. Whatever the outcomes, the pursuit of regeneration of the periodontal tissues remains a goal worth pursuing for our patients. The aim of the review, therefore is to update clinicians on the recent advances in both materials and techniques in periodontal regenerative procedures and to highlight the importance of both patient factors and the technical aspects of regenerative procedures.

Dehydrothermally Cross-Linked Collagen Membrane with a Bone Graft Improves Bone Regeneration in a Rat Calvarial Defect Model

In this study, the bone regeneration efficacy of dehydrothermally (DHT) cross-linked collagen membrane with or without a bone graft (BG) material was evaluated in a critical-sized rat model. An 8-mm-diameter defect was created in the calvaria of 40 rats, which were randomized into four groups: (1) control; (2) DHT; (3) BG; and, (4) DHT + BG. Evaluations were made at 2 and 8 weeks after surgery using micro-computed tomographic (micro-CT), histological, and histomorphometric analyses. Micro-CT analysis showed an increase in the new bone volume (NBV) of the BG and DHT + BG groups at 2 weeks after surgery, representing a significant difference (p < 0.05). At 8 weeks after surgery, the NBV increased in all four groups. However, larger NBVs were observed in the BG and DHT + BG groups, and a significant difference was no longer observed between the two groups. Histologic analysis demonstrated that the graft materials sustained the center of the defect in the BG and DHT + BG groups, which was shown in histomorphometric analysis as well. These results suggest that DHT membrane is a safe biomaterial with adequate tissue integration, and has a positive effect on new bone formation. Moreover, the best effects were achieved when DHT was used in conjunction with BG materials.

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

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

Structural determinants of hydration, mechanics and fluid flow in freeze-dried collagen scaffolds

Freeze-dried scaffolds provide regeneration templates for a wide range of tissues, due to their flexibility in physical and biological properties. Control of structure is crucial for tuning such properties, and therefore scaffold functionality. However, the common approach of modeling these scaffolds as open-cell foams does not fully account for their structural complexity. Here, the validity of the open-cell model is examined across a range of physical characteristics, rigorously linking morphology to hydration and mechanical properties. Collagen scaffolds with systematic changes in relative density were characterized using Scanning Electron Microscopy, X-ray Micro-Computed Tomography and spherical indentation analyzed in a time-dependent poroelastic framework. Morphologically, all scaffolds were mid-way between the open- and closed-cell models, approaching the closed-cell model as relative density increased. Although pore size remained constant, transport pathway diameter decreased. Larger collagen fractions also produced greater volume swelling on hydration, although the change in pore diameter was constant, and relatively small at ∼6%. Mechanically, the dry and hydrated scaffold moduli varied quadratically with relative density, as expected of open-cell materials. However, the increasing pore wall closure was found to determine the time-dependent nature of the hydrated scaffold response, with a decrease in permeability producing increasingly elastic rather than viscoelastic behavior. These results demonstrate that characterizing the deviation from the open-cell model is vital to gain a full understanding of scaffold biophysical properties, and provide a template for structural studies of other freeze-dried biomaterials.

STATEMENT OF SIGNIFICANCE

Freeze-dried collagen sponges are three-dimensional microporous scaffolds that have been used for a number of exploratory tissue engineering applications. The characterization of the structure-properties relationships of these scaffolds is necessary to understand their biophysical behavior in vivo. In this work, the relationship between morphology and physical properties in the dry and hydrated states was investigated across a range of solid concentrations in the scaffolds. The quantitative results provided can aid the design of scaffolds with a target trade-off between mechanical properties and structural features important for their biological activity.

Sequential healing of onlay bone grafts using combining biomaterials with cross-linked collagen in dogs

OBJECTIVES

The aim of this study was to observe the sequential healing of onlay grafts in terms of the volumetric and histologic changes using different bone substances and absorbable membranes according to the presence of collagen cross-linking.

MATERIAL AND METHODS

Four groups involving onlay grafting with different materials were randomly assigned to both sides of the maxillae of 15 beagle dogs: (i) control group without any treatment; (ii) group NN, bovine hydroxyapatite incorporated into a non-cross-linked collagen matrix (BHC) + non-cross-linked collagen membrane (NCCM); (iii) group NC, BHC + cross-linked collagen membrane (CCM); and (iv) group CC, porcine hydroxyapatite incorporated into a cross-linked collagen matrix + CCM. Radiographic and histological analyses were performed after three different healing periods: 4, 8 and 12 weeks.

RESULTS

At week 4, the bone substances were well localized under the barrier membrane in groups NC and CC, while the bone substances became spread out and flattened in group NN. Similarly, the augmented height was significantly greater in groups NC and CC (2.55 and 2.51 mm, respectively; median) than in group NN (1.96 mm, P < 0.001, both). The percentages of newly formed bone were significantly higher at week 12 than at weeks 4 and 8 in all of the groups. The NCCM showed an earlier angiogenesis pattern than the CCM; however, earlier degradation was observed at week 12.

CONCLUSION

Combining biomaterials with cross-linked collagen might contribute to maintaining its initial morphology with excellent biocompatibility in early healing period of lateral onlay grafts.

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

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

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

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

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

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

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

Soft Tissue Augmentation with Silk Composite Graft

PURPOSE

The objective of this study was to evaluate the interaction between 4-hexylresorcinol (4HR) and antibody as that affects the performance of a silk-4HR combination graft for soft tissue augmentation in an animal model.

METHODS

The silk graft materials consisted of four types: silk+10% tricalcium phosphate (TCP) (ST0), silk+10% TCP+1% 4HR (ST1), silk+10% TCP+3% 4HR (ST3), and silk+10% TCP+6% 4-HR (ST6). The antibody binding assay tested the 4HR effect and scanning electron microscopic (SEM) exam was done for silk grafts. The animal experiment used a subcutaneous pocket mouse model. The graft - SH0 or SH1 or SH3 or SH6 - was placed in a subcutaneous pocket. The animals were killed at one, two, and four weeks, postoperatively. The specimens were subjected to histological analysis and lysozyme assay.

RESULTS

Groups with 4HR applied showed lower antibody binding affinity to antigen compared to groups without 4HR. In the SEM examination, there was no significant difference among groups. Histological examinations revealed many foreign body giant cells in ST0 and ST1 group at four weeks postoperatively. Both ST3 and ST6 groups developed significantly lower levels of giant cell values compared to ST0 and ST1 groups (P <0.001) at four weeks postoperatively. In the lysozyme assay, the ST1 and ST3 groups showed denser signals than the other groups.

CONCLUSION

4HR combined silk implants resulted in high levels of vascular and connective tissue regeneration.

Comparison of ADM and Connective Tissue Graft as the Membrane in Class II Furcation Defect Regeneration: A Randomized Clinical Trial

Background and aims. Furcally-involved teeth present unique challenges to the success of periodontal therapy and influence treatment outcomes. This study aimed to assess to compare use of ADM and connective tissue membrane in class II furcation defect regeneration.

Materials and methods. 10 patient with 2 bilaterally class II furcation defects in first and/or second maxilla or man-dibular molar without interproximal furcation involvement, were selected. Four weeks after initial phase of treatment, before and thorough the surgery pocket depth (PD), clinical attachment level to stent (CAL-S), free gingival margin to stent(FGM-S) , crestal bone to stent (Crest-S), horizontal defect depth to stent (HDD-S) and vertical defect depth to stent (VDD-S) and crestal bone to defect depth measured from stent margin. Thereafter, one side randomly treated using connective tissue and DFDBA (study group) and opposite side received ADM and DFDBA (control group). After 6 months, soft and hard tissue parameters measured again in re-entry.

Results. Both groups presented improvements after therapies (P & 0.05). No inter-group differences were seen in PD re-duction (P = 0.275), CAL gain (P = 0.156), free gingival margin (P = 0.146), crest of the bone (P = 0.248), reduction in horizontal defects depth (P = 0.139) and reduction in vertical defects depth (P = 0.149).

Conclusion. Both treatments modalities have potential of regeneration without any adverse effect on healing process. Connective tissue grafts did not have significant higher bone fill compared to that of ADM.

Periosteum as a barrier membrane in the treatment of intrabony defect: A new technique

OBJECTIVE

The purpose of the study was to evaluate the clinical effectiveness of periosteum as a barrier membrane for the treatment of intrabony defects.

MATERIALS AND METHODS

The study was conducted in patients having bilateral intrabony defects. A total of 20 intrabony defects in 10 patients were treated, out of which 10 defects received periosteal barrier and the other 10 defects received conventional open flap debridement procedure. The efficacy of the treatment was assessed using clinical parameters and dentascan.

RESULTS

Statistically significant gain in clinical attachment level (CAL) was found in the test group (2.00 ± 0.26 mm) as compared to the control group (0.60 ± 0.22 mm). In both the treatment modalities (test and control groups), a significant decrease in probing pocket depth of 3.90 ± 0.35 mm and 2.90 ± 0.31 mm was observed, respectively. The difference between the two groups was not statistically significant. Bone defect fill was 1.40 ± 0.16 mm for the test group and 0.90 ± 0.18 mm for the control group, but the difference observed was not statistically significant.

CONCLUSION

The results of this study show that periosteal barrier membrane can be a better alternative of barrier membranes for the treatment of intrabony defects.

Biodegradation pattern and tissue integration of native and cross-linked porcine collagen soft tissue augmentation matrices - an experimental study in the rat

INTRODUCTION

Within the last decades, collagen types I and III have been established as a sufficient biomaterial for GBR and GTR procedures. They might also be an adequate matrix for soft tissue augmentations. However, collagen materials differ significantly regarding resorption time, biodegradation pattern and the invasion of inflammatory cells.The aim of the present study was to compare the biodegradation and tissue integration of native, differently processed and cross-linked collagen scaffolds in rats.

METHODS

Four experimental porcine collagen matrices of 1.0 mm thickness, developed for soft tissue augmentation procedures, were tested. Based on the same native dermal Type I and III collagen, native (ND, Mucoderm prototype), specifically defatted (DD), ethylene dioxide cross-linked (ECL) and dehydrothermally cross-linked (DCL) dermis collagen (AAP/Botiss Biomaterials, Berlin, Germany) were evaluated. Two specimens of 1 × 1 cm were fixed around a non-absorbable spacer using non-absorbable sutures. After rehydration, specimens (N = 8) were randomly allocated in unconnected subcutaneous pouches on the back of 40 Wistar rats. Rats were divided into five groups (1, 2, 4, 8 and 12 weeks), including eight animals each. After each period, eight rats were sacrificed and explanted specimens were prepared for histological analysis. The following parameters were evaluated: membrane thickness as a sign of biodegradation and volume stability, cell ingrowth, vascularization, tissue integration and foreign body reaction.

RESULTS

Biodegradation pattern of the non cross-linked collagen scaffolds differed only slightly in terms of presence of inflammatory cells and cell invasion into the matrix. In terms of biodegradation, ECL displayed a considerable slower resorption than ND, DCL and DD. Chemical cross-linking using ethylene dioxide showed a significant higher invasion of inflammatory cells.

CONCLUSION

Within the limits of the present study it was concluded that the processing techniques influenced the collagen properties in a different intensity. Dehydrothermal cross-linking and special defatting did not notably change the biodegradation pattern, whereas cross-linking using ethylene dioxide led to significant higher volume stability of the matrix. However, ECL showed an increased inflammatory response and compromised tissue integration. Therefore, ethylene dioxide seems to be not suitable for stabilization of collagen matrices for soft tissue augmentation procedures.

Mechanical & cell culture properties of elastin-like polypeptide, collagen, bioglass, and carbon nanosphere composites

Collagen, the most commonly used extra-cellular matrix protein for tissue engineering applications, displays poor mechanical properties. Here, we report on the preparation and characterization of novel multi-component composite systems that incorporate a genetically engineered, biocompatible polymer (elastin-like polypeptide, ELP), biodegradable ceramic (45S5 bioglass), carbon nanosphere chains (CNSC), and minimal amount (~25% w/w) of collagen. We hypothesized that incorporation of bioglass and CNSC would improve mechanical properties of the composites. Our results showed that the tensile strength and elastic modulus nearly doubled after addition of the bioglass and CNSC compared to the control ELP-collagen hydrogels. Further, MC3T3-E1 pre-osteoblasts were cultured within the composite hydrogels and a thorough biochemical and morphological characterization was performed. Live/dead assay confirmed high cell viability (>95%) for all hydrogels by day 21 of culture. Alkaline phosphatase (ALP) activity and osteocalcin (OCN) production assessed the pre-osteoblast differentiation. Normalized ALP activity was highest for the cells cultured within ELP-bioglass-collagen hydrogels, while normalized OCN production was equivalent for all hydrogels. Alizarin red staining confirmed the mineral deposition by the cells within all hydrogels. Thus, the multi-component composite hydrogels displayed improved mechanical and cell culture properties and may be suitable scaffold materials for bone tissue engineering.

Gore-tex(®) versus resolut adapt(®) GTR membranes with perioglas(®) in periodontal regeneration

Background:

Successful reconstruction of periodontal tissues destroyed due to periodontitis has been an evasive goal for the periodontists. Several GTR materials and bone grafts have been tried with varied success rates.

Aims and Objectives:

The aim of the present study was to evaluate and compare the efficacy of non-resorbable (GoreTex^®) and bioabsorbable (Resolut Adapt^®) membranes in combination with bioactive glass (PerioGlas^®) in the treatment of periodontal intrabony defects.

Materials and Methods:

Ten chronic periodontitis patients having bilateral matched intrabony defects were treated with non-resorbable membrane (GoreTex^®) and bioactive glass or the bioresorbable membrane (Resolut Adapt^®) and bioactive glass in split mouth design. Clinical parameters like plaque index, gingival index, probing pocket depth, clinical attachment level, and gingival recession were recorded at baseline and 9 months post-operatively. Similarly, radiographic (linear CADIA) and intra-surgical (re-entry) measurements were evaluated at baseline and 9 months post-operatively).

Results:

Both the membrane groups showed clinically and statistically significant improvement in clinical parameters i.e., reduction in probing depth (4.6 ± 1.4 mm) vs. 3.7 ± 1.3 mm) and gain in clinical attachment level (4.6 + 1.6 vs. 3.2 ± 1.5 mm) for non-resorbable and bioresorbable membrane groups, respectively. Similar trend was observed when radiographical and intra-surgical (re-entry) measurements were evaluated and compared, pre- and post-operatively at 9 months. However, on comparison between the two groups, the difference was statistically not significant.

Conclusion:

Both the barrier membranes i.e., non-resorbable (Gore-Tex^®) and bioabsorbable (Resolut Adapt^®) membranes in combination with bioactive glass (PerioGlas^®) were equally effective in enhancing the periodontal regeneration.

Non-cross-linked porcine-based collagen I-III membranes do not require high vascularization rates for their integration within the implantation bed: a paradigm shift

There are conflicting reports concerning the tissue reaction of small animals to porcine-based, non-cross-linked collagen I-III membranes/matrices for use in guided tissue/bone regeneration. The fast degradation of these membranes/matrices combined with transmembrane vascularization within 4 weeks has been observed in rats compared with the slow vascularization and continuous integration observed in mice. The aim of the present study was to analyze the tissue reaction to a porcine-based non-cross-linked collagen I-III membrane in mice. Using a subcutaneous implantation model, the membrane was implanted subcutaneously in mice for up to 60 days. The extent of scaffold vascularization, tissue integration and scaffold thickness were assessed using general and specialized histological methods, together with a unique histomorphometrical analysis technique. A dense Bombyx mori-derived silk fibroin membrane was used as a positive control, whilst a polytetrafluoroethylene (PTFE) membrane served as a negative control. Within the observation period, the collagen membrane induced a mononuclear cellular tissue response, including anti-inflammatory macrophages and the absence of multinucleated giant cells within its implantation bed. Transmembrane scaffold vascularization was not observed, whereas a mild scaffold vascularization was generated through microvessels located at both scaffold surfaces. However, the silk fibroin induced a mononuclear and multinucleated cell-based tissue response, in which pro-inflammatory macrophages and multinucleated giant cells were associated with an increasing transmembrane scaffold vascularization and a breakdown of the membrane within the experimental period. The PTFE membrane remained as a stable barrier throughout the study, and visible cellular degradation was not observed. However, multinucleated giant cells were located on both interfaces. The present study demonstrated that the tested non-cross-linked collagen membrane remained as a stable barrier membrane throughout the study period. The membrane integrated into the subcutaneous connective tissue and exhibited only a mild peripheral vascularization without experiencing breakdown. The silk fibroin, in contrast, induced granulation tissue formation, which resulted in its high vascularization and the breakdown of the material over time. The presence of multinucleated giant cells at both interfaces of the PFTE membrane is a sign of its slow cellular biodegradation and might lead to adhesions between the membrane and its surrounding tissue. This hypothesis could explain the observed clinical complications associated with the retrieval of these materials after guided tissue regeneration.

Treatment of periodontal defects in dogs using an injectable composite hydrogel/biphasic calcium phosphate

An injectable composite silanized hydroxypropyl methyl cellulose/biphasic calcium phosphate (Si-HPMC/BCP) has been investigated in humans with promising results. The aim of this study was to evaluate his efficacy for treating periodontal defects (canine fenestration and premolar furcation) in dog models. At 3 months, we observed that bone formation around BCP particles in furcation model is more discernible but not statistically significant in defects filled with Si-HPMC/BCP compared to healing in control. We suggest that BCP particles sustain the bone healing process by osteoconduction, while the Si-HPMC hydrogel enhances intergranular cohesion and acts as an exclusion barrier. Furthermore, bone ingrowth is not so distinctive in superficial defects where the biomaterial appears unstable. These results with Si-HPMC/BCP are encouraging. In addition, this biomaterial is easy to use and simplifies the process of filling periodontal lesions. However, more researches are needed to improve the viscosity and hardness to adjust the material to the specificities of periodontal defects.

Porcine peritoneum as source of biocompatible collagen in mice

PURPOSE: To investigate the biocompatibility and biodegradability of a membrane made from porcine peritoneum. METHODS: The membrane (5x5 mm) was inserted in the subcutaneous tissue on the back of 15 mice, which were killed after 1, 3 and 9 weeks (ISO 10993-6). The cellular components of the inflammatory response and degradation of the membrane were analyzed in hematoxylin-eosin-stained histological sections. RESULTS: After one week, mononuclear cells were observed inside the membrane. After three weeks, the material was almost completely absorbed. After nine weeks, there was no presence of material and there were signs of tissue remodeling. There was neither a foreign body reaction nor signs of tissue necrosis. CONCLUSION: The collagen membrane derived from porcine peritoneum is biocompatible and bioabsorbable when implanted in the subcutaneous tissue of mice.

Bio-degradation of a resorbable collagen membrane (Bio-Gide) applied in a double-layer technique in rats

OBJECTIVE

The aim of this study was to evaluate histologically the bio-degradation of two layers of Bio-Gide((R)) (BG) membrane, as compared with that of a single layer.

MATERIAL AND METHODS

Two circular calvarial bony defects, 5 mm in diameter, were made in 24 Wistar rats. BG membrane, labeled with biotin, was cut into 5-mm-diameter disks, and placed in defects either as a mono-layer membrane (MLM) or as a double-layer membrane (DLM). Rats were sacrificed after 4 or 9 weeks and histology was performed. Membranes were stained with horseradish peroxidase-conjugated streptavidin and aminoethyl carbazole as a substrate for detection of biotinylated collagen. The area of collagen and thickness of the residual membranes were measured by image analysis software. Statistical analysis was performed using the non-parametric Wilcoxon's signed-ranks test.

RESULTS

At 4-week collagen area per measurement window within the DLM sites (0.09+/-0.05 mm(2)) was significantly greater (P<0.01) than that in the MLM sites (0.047+/-0.034 mm(2)). At 9 weeks, the collagen area was also greater in the DLM sites (0.037+/-0.026 mm(2)) compared with that of the MLM sites (0.025+/-0.016 mm(2)); however, this difference did not reach statistical significance. The rate of membrane degradation, calculated as percent membrane lost compared with baseline, was similar for the DLM and MLM at both time points ( approximately 60% at 4 weeks and approximately 80% at 9 weeks). In addition, the residual DLM thickness at 4 weeks (475.5+/-73.77 mum) was significantly (P<0.01) greater than that of MLM (262.38+/-48.01 mum). At 9 weeks, membrane thickness was also greater in the DLM sites (318.22+/-70.45 mum) compared with that of the MLM sites (183.32+/-26.72 mum); however, this difference did not reach statistical significance. The reduction in thickness between 4 and 9 weeks was 30% for MLM and 33% for DLM.

DISCUSSION

The use of a double layer of BG membrane results in a barrier of increased collagen area and thickness, compared with application of a single layer.

In vitro evaluation of various bioabsorbable and nonresorbable barrier membranes for guided tissue regeneration

BACKGROUND

Different types of bioabsorbable and nonresorbable membranes have been widely used for guided tissue regeneration (GTR) with its ultimate goal of regenerating lost periodontal structures. The purpose of the present study was to evaluate the biological effects of various bioabsorbable and nonresorbable membranes in cultures of primary human gingival fibroblasts (HGF), periodontal ligament fibroblasts (PDLF) and human osteoblast-like (HOB) cells in vitro.

METHODS

Three commercially available collagen membranes [TutoDent (TD), Resodont (RD) and BioGide (BG)] as well as three nonresorbable polytetrafluoroethylene (PTFE) membranes [ACE (AC), Cytoplast (CT) and TefGen-FD (TG)] were tested. Cells plated on culture dishes (CD) served as positive controls. The effect of the barrier membranes on HGF, PDLF as well as HOB cells was assessed by the Alamar Blue fluorometric proliferation assay after 1, 2.5, 4, 24 and 48 h time periods. The structural and morphological properties of the membranes were evaluated by scanning electron microscopy (SEM).

RESULTS

The results showed that of the six barriers tested, TD and RD demonstrated the highest rate of HGF proliferation at both earlier (1 h) and later (48 h) time periods (P < 0.001) compared to all other tested barriers and CD. Similarly, TD, RD and BG had significantly higher numbers of cells at all time periods when compared with the positive control in PDLF culture (P < or = 0.001). In HOB cell culture, the highest rate of cell proliferation was also calculated for TD at all time periods (P < 0.001). SEM observations demonstrated a microporous structure of all collagen membranes, with a compact top surface and a porous bottom surface, whereas the nonresorbable PTFE membranes demonstrated a homogenous structure with a symmetric dense skin layer.

CONCLUSION

Results from the present study suggested that GTR membrane materials, per se, may influence cell proliferation in the process of periodontal tissue/bone regeneration. Among the six membranes examined, the bioabsorbable membranes demonstrated to be more suitable to stimulate cellular proliferation compared to nonresorbable PTFE membranes.

Efficacy of xenogeneic bone grafting with guided tissue regeneration in the management of bone defects after surgical endodontics

PURPOSE

The purpose of this prospective clinical trial was to monitor the outcomes of periradicular surgery in large periapical lesions with or without guided tissue regeneration (GTR) and anorganic bovine bone.

MATERIALS AND METHODS

All teeth in the study revealed a periradicular lesion measuring at least 10 mm. A total of 63 teeth in 44 patients were included according to specific selection criteria. In the test group, after root end filling was completed, the defect was filled with anorganic bovine bone and was covered with a resorbable collagen membrane. In the control group, neither graft nor membrane was used.

RESULTS

A total of 59 teeth in 41 patients were evaluable at 1-year follow-up. Of these, 24 teeth belonged to the test group and 35 to the control group. Overall, 46 teeth (78%) had successfully healed, 10 (16.9%) demonstrated uncertain healing, and 3 exhibited treatment failure. Investigators found no statistically significant differences in outcome between test and control groups.

CONCLUSIONS

The present study showed that the use of GTR in association with anorganic bovine bone in the treatment of patients with large periradicular lesions of strictly endodontic origin has no beneficial effect on outcome.

Combined use of platelet-rich plasma and bone grafting with or without guided tissue regeneration in the treatment of anterior interproximal defects

BACKGROUND

The aim of periodontal therapy is to prevent tissue destruction while achieving the regeneration of damaged tissues. Platelet-rich plasma (PRP) is used to generate new bone, periodontal ligament, and new attachment with a strategy based on the modulation and enhancement of wound healing through an autologous source for growth factors obtained from the patient's own blood. The purpose of the present study was to evaluate the efficacy of PRP when used in combination with beta-tricalcium phosphate (beta-TCP) alloplastic graft material and collagen barrier membrane in the treatment of anterior interproximal intrabony defects.

METHODS

Thirty interproximal intrabony defects in 25 systemically healthy patients were selected for the study. Defects were distributed randomly and equally into three groups: graft alone (beta-TCP), graft + PRP, and graft + PRP + membrane. The plaque index, gingival index, periodontal probing depth, relative attachment level, transgingival probing measurement, and radiographic analyses were performed at baseline and repeated after 6, 9, and 12 months.

RESULTS

At the end of 12 months, relative attachment gain was 2.4, 2.1, and 2.5 mm in the three treatment groups, respectively. No statistically significant differences in clinical and radiographic measurements were observed among the groups.

CONCLUSIONS

All options were effective in the treatment of anterior interproximal intrabony defects. The results also suggested that PRP added no clinical benefit to beta-TCP alloplastic graft material used alone or in combination with GTR.

Guided bone augmentation around a titanium bone-anchored hearing aid implant in canine calvarium: an initial comparison of two barrier membranes

BACKGROUND

The placement of a bone-anchored hearing aid (BAHA) implant in young children may be hampered by the presence of thin, poor-quality calvarial bone. The use of extraskeletal guided skull bone augmentation around the titanium implant is one potential solution.

PURPOSE

To compare the effectiveness of a collagen membrane BioSISt (Cook Biotech Inc., Lafayette, IN, USA) and a PGA/PLA barrier membrane, Osseoquest (W.L. Gore & Associates, Flagstaff, AZ, USA) in promoting extraskeletal bone formation, when combined with cancellous bone graft, around a titanium implant in the canine calvarium. The quality and quantity of bone tissue was compared.

MATERIALS AND METHODS

A 4-mm titanium BAHA implant was placed in the cranial parietal bone of 11 dogs. The implant protruded from the bone surface by a measured distance. Two groups, each of three dogs, received an implant, cancellous bone graft, and either a BioSISt or Osseoquest membrane. Three dogs received implant and bone graft (positive controls), and two received an implant only (negative controls). Samples were retrieved at 3, 6, and 9 months after placement. Undecalcified histologic and histomorphometric assessments were made of the augmented bone thickness, and bone gain factors were calculated for each sample group.

RESULTS

The process of osseointegration of the implants was ongoing and increased over time. Bone generation occurred with both test membranes and the early trabecular bone that formed, matured, and remodelled to compact bone at 9 months. BioSISt membrane samples showed superior quality and quantity of augmented bone compared with Osseoquest samples that exhibited thinner bone with persistent inflammation. Quantitatively, the BioSISt samples showed statistically greater new bone contact and bone area than both the positive and negative controls, whereas Osseoquest samples did not. The bone gain factor was statistically greater for BioSiSt samples when compared to the positive and negative controls whereas the Osseoquest samples were not.

CONCLUSIONS

In this study, the collagen BioSISt membrane promoted bone formation of superior quality and quantity compared with the polyglycolic/polylactic acid-based Osseoquest membrane and positive and negative controls over 9 months. Further investigation of the use of the collagen BioSISt membrane for cranial bone augmentation is warranted.

Healing of intrabony peri-implantitis defects following application of a nanocrystalline hydroxyapatite (Ostimtm) or a bovine-derived xenograft (Bio-Osstm) in combination with a collagen membrane (Bio-Gidetm). A case series

OBJECTIVES

The aim of the present case series was to evaluate the healing of intrabony peri-implantitis defects following application of a nanocrystalline hydroxyapatite (NHA) or a bovine-derived xenograft in combination with a collagen membrane (BDX+BG).

MATERIAL AND METHODS

Twenty-two patients having moderate peri-implantitis (n=22 intrabony defects) were randomly treated with (i) access flap surgery (AFS) and the application of NHA, or with AFS and the application of BDX+BG. Clinical parameters were recorded at baseline and after 6 months of non-submerged healing.

RESULTS

Post-operative wound healing revealed that NHA compromized initial adhesion of the mucoperiosteal flaps in all patients. At 6 months after therapy, NHA showed a reduction in the mean PD from 7.0+/-0.6 to 4.9+/-0.6 mm and a change in the mean clinical attachment loss (CAL) from 7.5+/-0.8 to 5.7+/-1.0 mm. In the BDX+BC group, the mean PD was reduced from 7.1+/-0.8 to 4.5+/-0.7 mm and the mean CAL changed from 7.5+/-1.0 to 5.2+/-0.8 mm.

CONCLUSION

Within the limits of the present case series, it can be concluded that at 6 months after surgery both therapies resulted in clinically important PD reductions and CAL gains.