Collagen Matrix Group Research Articles

Periimplant soft tissue volume changes after connective tissue grafting. The autologous connective tissue graft vs. the porcine collagen matrix. A clinical follow‐up case series

Background The thickness of peri-implant soft tissue is very important in the high risk esthetic area. Especially in advanced cases, i.e. high lip line, thin gingival biotype, loss of soft or hard tissues or bony atrophy, soft tissue grafting can be indicated in order to avoid gingival recession and periimplantitis. Gold standard is the autologous subepithelial connective tissue graft (SCTG) of the palate. To avoid tissue removal, porcine collagen matrices have been introduced as possible alternatives. Aim/Hypothesis This clinical study evaluates a porcine collagen matrix (CM) in comparison to the subepithelial connective tissue graft (SCTG) from the palate for soft tissue thickening around implants with a 3D follow- up. Material and Methods Patients (n = 12) were included after implant placement in the esthetic area with buccal tissue deficit. At the time point of implant exposure, buccal soft tissue were either thickened with the CM (n = 6) or the SCTG (n = 6). Impressions with a scan optimized vinylsiloxanether (Identium® Scan, Kettenbach GmbH, Eschenburg, Germany) were taken before augmentation (i), after surgery (ii), after 10 (iii), 30 (iv), 90 (v) and 180 days (vi). The impressions were optically scanned with a high precision scanner (Atos II Triple Scan, GOM GmbH, Braunschweig, Germany). The acquired data was visualized and superimposed with the ATOS Professional software (GOM GmbH, Braunschweig, Germany). The region of interest (ROI) was defined at the buccal area from the margin of the suprastructure to the mucogingival junction at the implant site and to the 2 adjacent teeth (primary outcome variable- volume increase in mm3+ secondary outcome variables- volume increase in%, mean and maximum thickness increases in mm. Results The evaluation of the region of interest at the different time points showed that there was a volume increase in both groups after surgery. After ten days, volume further increased in the SCTG group (183.88 mm3 = 139.03%) compared to the CM group (80.74 mm3 = 71.03%). This was a thickness increase (mm) of 2.31 mm in the SCT group and 1.12 mm in the CM group. Volume and thickness decreased in both groups over time (6 months- SCTG- 61.75 mm3 = 43.61%+ CM- 19.56 mm3 = 18.24%). This resulted in a thickness increase of 0.3 mm in the CM and 0.8 mm in the SCTG group with statistically significant difference after 6 months. Conclusions and Clinical Implications After 6 months, soft tissues thickness gain with the use of the porcine collagen matrix was significantly lower than with the use of the autologous subepithelial connective tissue graft. The SCTG still remains the gold standard for such procedures.

Osteogenic prospective of deriving human dental stem cells in collagen matrix boost.

Stem cells derived from oral tissue represent a highly attractive alternative source for clinical bone regeneration because they can be collected by non-invasive or minimally invasive procedures. Herein, we describe the human dental stem cells (DSCs) deriving from buccal fat pads (BFP), dental pulp (DP) of impacted teeth, and periodontal ligaments (PDL) to obtain BFPSCs, DPSCs, and PDLSCs, respectively. Cells were purified with selected medium and expanded through passages in stem cell culture medium. Purified cells were characterized for stemness by their growth rate, immunostaining, and multilineage differentiation ability. They showed plastic adherence, expression of stemness-specific markers, and multilineage differentiation potential. Immunocytochemistry analysis confirmed that DPSCs had more osteogenic potential than BFSCs and PDLSCs. Calcium-rich deposits, evaluated by von Kossa and Alizarin red staining, showed greater mineralization when DPSCs were cultured on collagen type I matrix than without collagen. Furthermore, DPSC-seeded collagen type I matrix maintained consistent osteogenesis and boosted mineral formation by 1-2 weeks over that in DPSCs cultured without collagen. Radiographic analysis of DPSC-seeded collagen type I matrix transplanted into rat cranial defects showed significant bone regeneration after 8 weeks. These results suggested that the redundant oral tissue can be used as a source of adult multipotent stem cells for clinical bone regeneration. Triple overlay images with biomarkers (red), nuclei (blue) and bright field morphology of DPSCs. The specifically osteo-differentiation shown by osteocalcin (left) expression and lack of sox9 (right) expressed in the images below which were cultured with collagen matrix, contrast with no collagen matrix group above.

Collagen matrix vs mitomycin-C in trabeculectomy and combined phacoemulsification and trabeculectomy: a randomized controlled trial.

BackgroundAntifibrotic agents are commonly utilized to enhance the success rates of trabeculectomy. Novel approaches to further improve success rates and reduce the risks of complications are needed. The purpose of this study was to compare intraocular pressure (IOP)-lowering efficacy and safety of trabeculectomy or combined phacoemulsification and trabeculectomy with mitomycin-C (MMC) vs. Collagen Matrix (CM).MethodsA prospective, multicenter, randomized controlled trial was performed. Ninety-five eyes of 94 patients with uncontrolled glaucoma despite medical therapy, without previous incisional glaucoma surgery underwent trabeculectomy (85 eyes) or combined phacoemulsification and trabeculectomy (10 eyes) and were randomized to MMC or CM. One eye of each subject was analyzed. Patients were followed for 24 months. The criteria for complete success were IOP >5 and ≤21 mmHg with at least a 20% reduction below medicated baseline without additional glaucoma surgery or medications. The main outcome measures were complete success rates at 24 months with Kaplan-Meier analysis and incidence of adverse events.ResultsThe baseline IOPs were 20.4 ± 6.0 mmHg and 21.2 ± 6.1 (mean ± standard deviation, p = 0.49) on 3.2 ± 1.1 and 3.1 ± 1.0 medications (p = 0.53) compared to 11.8 ± 5.2 and 12.8 ± 3.7 (p = 0.36) on 0.5 ± 0.8 and 0.6 ± 1.0 medications (p = 0.63) at 2 years in the MMC and CM groups, respectively. Kaplan-Meier analysis demonstrated complete success rates were similar in both groups at 24 months: 38.4 ± 7.6% with MMC and 56.2 ± 7.9% with CM (mean ± standard error, p = 0.112, log rank test); however, a significantly higher incidence of failure due to persistent hypotony was observed with MMC (p = 0.002).ConclusionsUse of the CM implant at the time of trabeculectomy or combined phacoemulsification and trabeculectomy is associated with similar complete success rates compared to adjunctive MMC; however, the risk of persistent hypotony is higher with MMC.Trial registrationClinicalTrials.gov registration number NCT01440751.Registered 9/14/11Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-016-0393-z) contains supplementary material, which is available to authorized users.

Prospective Clinical and Radiographic Study of Alveolar Ridge Preservation Combining Freeze-Dried Bone Allograft With Two Xenogeneic Collagen Matrices.

Tooth extractions are followed by significant dimensional changes in the alveolar crest that may preclude implant placement. This randomized, controlled, prospective compares the preservation of soft and hard tissue dimensional changes after alveolar ridge preservation (ARP) using two membranes consisting of collagen matrix (CM) or extracellular matrix (ECM) as barriers over freeze-dried bone allograft (FDBA). Standardized clinical and radiographic measurements of soft and hard tissues were recorded by means of a stent before and 4 months after ARP. The surgery entailed sulcular incisions with minimal flap elevation and repositioning without advancement. Of 11 patients in the CM group and 12 in the ECM group who completed the study, gingival thickness (GT) increased from 0.1 to 0.2 mm for both groups along with a 0.5-mm decrease in the width of keratinized tissue after healing. Reductions in ridge width were most pronounced on the coronal aspect, 1.8 mm for CM and 2.0 mm for ECM, whereas vertical reduction was most pronounced on the buccal aspect, 0.7 to 1.0 mm. Differences between groups were not statistically significant. However, significant correlation for changes in GT (P = 0.001) and crestal bone width (P = 0.002) with preoperative buccal plate thickness (BPT) was observed. Both xenogeneic collagen matrices combined with FDBA were effective in maintaining soft tissues and minimizing ridge resorption in all dimensions after ARP. BPT was an important determinant for amount of change in crestal GT and ridge width.

Counting CD4(+) and CD8(+) T cells in the spleen: a novel in vivo method for assessing biomaterial immunotoxicity.

As immunotoxicity assessments of newly developed biomaterials are often restricted to use in assessment of local tissue response at the implantation site, they do not always show an immune response acceptable to qualify them for clinical use. We tested a new method to assess systemic toxicity: counting the CD4+ and CD8+ cells in the spleen. Three different biomaterials were subcutaneously implanted in three groups of rats for the same time period. After 31 days, their spleens were harvested, and CD4+ and CD8+ cells were counted. The mean CD4+/CD8+ cell counts were 24.5 ± 3.6/19.8 ± 4.0 (porous collagen matrix group), 25.5 ± 7.1/21.6 ± 3.8 [synthetic collagen matrix (Duragen®) group] and 28.1 ± 4.1/19.6 ± 3.7 (porcine dermis group). Differences in cell counts were not significant. The immunotoxic response generated against porous collagen matrix was comparable to that produced by a similar biomaterial already used clinically. This is, to the best of our knowledge, the first study on cytotoxic lymphocytes in the spleen to quantify systemic immune response to a biomaterial; however, such studies have been conducted with bacterial and viral antigens, and with vaccines. We believe that the present study provides a viable method for larger studies to confirm our current findings.

Healing of a xenogeneic collagen matrix for keratinized tissue augmentation.

To evaluate histologically the healing of a xenogeneic collagen matrix (CM) used to augment the width of keratinized tissue around teeth. The gingiva on the buccal aspect of mandibular and maxillary premolars was surgically excised on 12 minipigs. After 1 month of plaque accumulation, the resulting defects were randomly treated by a periosteal retention procedure (control site) or by placing a collagen matrix after an apically repositioned flap (CM) (test site). Clinical and histological outcomes were evaluated at 1, 4 and at 12 weeks. Clinically, no gain of keratinized tissue was noted in either group. Histometrically, the thickness of the gingival unit was significantly higher in the test group at 1 month, although these differences were not significant at 3 months. There was a tendency in the test group towards less bone resorption (0.7 mm) and apical displacement (0.5 mm) of the gingival margin at 3 months. The tested CM demonstrated uneventful healing, being resorbed within the surrounding tissues in absence of significant inflammation. When compared with periosteal retention alone, the CM group attained similar clinical and histological outcomes.

Vestibuloplasty: Porcine Collagen Matrix Versus Free Gingival Graft: A Clinical and Histologic Study

A free gingival graft (FGG) is currently the gold standard for augmenting small areas of keratinized mucosa. The porcine collagen matrix (CM) represents an alternative to autologous tissue harvesting. This study aims to compare the CM versus FGGs for augmenting keratinized peri-implant mucosa based on clinical and histologic evaluations. The study included 14 patients who underwent a vestibuloplasty with either a FGG from the palate (n = 7) or the CM (n = 7). An implant-fixed vestibular retention splint was inserted for 30 days. Follow-up examinations were performed at 4, 10, 30, and 90 days after surgery. Width of keratinized mucosa was measured in the region of each implant (days 10, 30, and 90). After 90 days, a biopsy was harvested for histologic and immunohistologic analyses. To characterize newly formed soft tissue, the authors stained for tissue-and differentiation-specific markers, cytokeratin (CK) 5/6, 13, and 14, to detect presence or absence of keratinization. The groups showed similar healing, with increased peri-implant keratinized mucosa. The CM group had overall significantly shorter operation times than the FGG group. Both groups showed similar overall shrinkage (32.98% CM versus 28.35% FGG). All biopsies showed a multilayered, keratinized, squamous epithelium. CKs 5/6 and 14 were detected in the basal and suprabasal layers, and spots of CK 13 were detected in the suprabasal layer. During the whole observation period, both groups showed comparable clinical and histologic outcomes. Within the limitations of the present study, CM seems to be a promising alternative for the regeneration of keratinized mucosa without tissue harvesting. Comparative long-term studies are needed to investigate changes over time.

Therapeutic Angiogenesis Using Basic Fibroblast Growth Factor in Combination with a Collagen Matrix in Chronic Hindlimb Ischemia

Although therapeutic angiogenesis by angiogenic cytokines is a feasible strategy to improve regional blood flow in ischemic regions, the optimal delivery mode needs to be established. Here we designed a complex of collagen matrix (CM) and basic fibroblast growth factor (bFGF) and evaluated its proangiogenic effect in ischemic hindlimbs. The bFGF-CM was prepared using lyophilization. The morphology, porosity and toxicity of CM were examined. The bFGF releasing profile and bioactivity of released bFGF were assessed. bFGF-CM was intramuscularly implanted into the rabbit ischemic hindlimb model. Oxygen saturation parameters (OSP) of ischemic hindlimbs was measured to evaluate the extremity perfusion at intervals. Histological examination was performed to evaluate the level of angiogenesis. The CM and bFGF-CM were of identical multiporous structure lacking cytotoxicity. The releasing profile lasted 10 days and the released bFGF remained bioactive. OSP in bFGF-CM group was significantly higher than that in CM, bFGF and ischemic groups at 2 and 4 weeks. The number of capillaries and mature vessels in bFGF-CM group were significantly greater than that in untreated control, CM and bFGF groups. Therefore, bFGF-CM enables the safe and effective long-term release of bFGF with improved angiogenesis in ischemic hindlimbs compared with CM devoid of bFGF.

Clinical efficacy of a xenogeneic collagen matrix in augmenting keratinized mucosa around implants: a randomized controlled prospective clinical trial

The aim of this controlled randomized clinical trial was to evaluate the efficacy of a xenogeneic collagen matrix (CM) to augment the keratinized tissue around implants supporting prosthetic restorations at 6months when compared with the standard treatment, the connective tissue autograft, CTG). This randomized longitudinal parallel controlled clinical trial studied 24 patients with at least one location with minimal keratinized tissue (≤1mm). The 6-month width of keratinized tissue. As secondary outcomes the esthetic outlook, the maintenance of peri-implant mucosal health and the patient morbidity were assessed pre-operatively and 1, 3, and 6months post-operatively. At 6months, Group CTG attained a mean width of keratinized tissue of 2.75 (1.5)mm, while the corresponding figure in Group CM was 2.8 (0.4)mm, the inter-group differences not being statistically significant. The surgical procedure in both groups did not alter significantly the mucosal health in the affected abutments. There was a similar esthetic result and significant increase in the vestibular depth in both groups as a result of the surgery. In the CM group it changed from 2.2 (3.3) to 5.1 (2.5)mm at 6months. The patients treated with the CM referred less pain, needed less pain medication, and the surgical time was shorter, although these differences were not statistically significant when compared with the CTG group. These results prove that this new CM was as effective and predictable as the CTG for attaining a band of keratinized tissue.

Ex vivo bone morphogenetic protein‐2 gene delivery using gingival fibroblasts promotes bone regeneration in rats

The aim of the present study was to investigate bone regeneration following ex vivo bone morphogenetic protein-2 (BMP-2) gene delivery using human gingival fibroblasts (HGFs) in rat calvarial defects. An 8 mm craniotomy defect was created in Sprague-Dawley rats. The animals were divided into four groups: (1) non-grafted group, the defect was left empty; (2) collagen matrix group, the defect was filled with collagen matrix only; (3) HGF group, the defect was filled with non-transduced HGFs on collagen matrix; (4) BMP-2/HGF group, the defect was filled with BMP-2 gene-transduced HGFs on collagen matrix. Animals were sacrificed at 2 and 4 weeks after surgery, and micro-computed tomographic and histologic observations were performed. The BMP-2/HGF group showed promoted osseous healing of calvarial defects, as compared with the other groups. At both 2 and 4 weeks, regenerated bone area was significantly greater in the BMP-2/HGF group than the other three groups. Quite a few number of transplanted HGFs were observed within the regenerated bone tissues. The results of this study suggest that ex vivo BMP-2 gene delivery induces prominent bone regeneration in vivo and HGFs may be useful as target cells for ex vivo gene therapy.

Clinical evaluation of a new collagen matrix (Mucograft® prototype) to enhance the width of keratinized tissue in patients with fixed prosthetic restorations: a randomized prospective clinical trial

The aim of this study was to test a new collagen matrix (CM) aimed to increase keratinized gingiva/mucosa when compared with the free connective tissue graft (CTG). This randomized longitudinal parallel controlled clinical trial studied 20 patients with at least one location with minimal keratinized tissue (<or=1 mm). The 6-month width of keratinized tissue. As secondary outcomes, the aesthetic outlook, the maintenance of periodontal health and the patient morbidity were assessed pre-operatively at 1, 3 and 6 months. At 6 months, the CTG attained a mean width of keratinized tissue of 2.6 (0.9) mm, while the CM was 2.5 (0.9) mm, these differences being insignificant. In both groups, there was a marked contraction (60% and 67%, respectively) although the periodontal parameters were not affected. The CM group had a significantly lower patient morbidity (pain and medication intake) as well as reduced surgery time. These results prove that this new CM was as effective and predictable as the CTG for attaining a band of keratinized tissue, but its use was associated with a significantly lower patient morbidity.

Histologic and Ultrastructural Study on Statin Graft in Rabbit Skulls

To study the early healing pattern of statin-induced osteogenesis, we examined the early histologic and ultrastructural pictures of bone defect healing with and without statin. Twenty-eight bone defects were created in the parietal bone of 14 New Zealand White rabbits. In the Statin Group of 7 rabbits, the defects were grafted with collagen matrix carriers mixed with statin solution. In the Collagen Matrix Group of 7 rabbits, the defects were grafted with collagen matrix carriers mixed with water for injection. The Statin Group and the Collagen Matrix Group were killed on day 1, 2, 3, 4, 5, 6, or 14 after surgery. Bone defects with surrounding tissues were prepared for histologic assessment. Bone defects of day 14 were also prepared for ultrastructural assessment. New bone was formed on day 5 in the defects grafted with statin. No cartilage intermediate stage was detected. This occurred 1 day earlier than for those grafted with the carrier alone. The bone defects of day 14 showed that an abundance of bone was formed in the Statin Group and osteocytes were identified ultrastructurally. This study supported statin-induced and accelerated bone formation locally.

Early healing pattern of statin-induced osteogenesis

We examined the early histological expressions of vascular endothelial growth factor (VEGF), bone morphogenetic protein (BMP)-2 and core binding factor (Cbfa1) in healing bones with and without a statin (simvastatin). Thirty bone defects were created in the parietal bones of 15 New Zealand white rabbits. In the statin group (n=9), the defects were grafted with carriers of collagen matrix mixed with simvastatin solution, and the animals were killed on days 1 (n=1), 2 (n=1), 3 (n=2), 4 (n=2), 5 (n=2) and 6 (n=1) after operation. In the collagen matrix group, the defects were grafted with carriers of collagen matrix mixed with water for injection, and killed on days 1-6 postoperatively. Immunolocalisation studies of the defects grafted with statin showed that VEGF was expressed on day 3 postoperatively, BMP-2 on day 4, Cbfa1 on day 5 and that new bone was formed by day 5. These events occurred one day earlier than in the group grafted with the carrier alone. The statin induced and accelerated formation of bone locally, and triggered the early expression of growth factors that regulate angiogenesis, differentiation of bone cells, and osteogenesis.

Effect of recombinant human osteogenic protein-1 on the healing of a freshly closed diaphyseal fracture

Osteogenic protein-1 (OP-1), or bone morphogenetic protein-7, is an osteoinductive morphogen that is involved in embryonic skeletogenesis and in bone repair. In bone defect models without spontaneous healing, local administration of recombinant human OP-1 (rhOP-1) induces complete healing. To investigate the ability of rhOP-1 to accelerate normal physiologic fracture healing, an experimental study was performed. In 40 adult female goats a closed tibial fracture was made, stabilized with an external fixator, and treated as follows: (1) no injection; (2) injection of 1 mg rhOP-1 dissolved in aqueous buffer; (3) injection of collagen matrix; and (4) injection of 1 mg rhOP-1 bound to collagen matrix. The test substances were injected in the fracture gap under fluoroscopic control. At 2 and 4 weeks, fracture healing was evaluated with radiographs, three-dimensional computed tomography (CT), dual-energy X-ray absorptiometry, biomechanical tests, and histology. At 2 weeks, callus diameter, callus volume, and bone mineral content at the fracture site were significantly increased in both rhOP-1 groups compared with the no-injection group. As signs of accelerated callus maturation, bending and torsional stiffness were higher and bony bridging of the fracture gap was observed more often in the group with rhOP-1 dissolved in aqueous buffer than in uninjected fractures. Treatment with rhOP-1 plus collagen matrix did not result in improved biomechanical properties or bony bridging of the fracture gap at 2 weeks. At 4 weeks there were no differences between groups, except for a larger callus volume in the rhOP-1 plus collagen matrix group compared with the control groups. All fractures showed an advanced stage of healing at 4 weeks. In conclusion, the healing of a closed fracture in a goat model can be accelerated by a single local administration of rhOP-1. The use of a carrier material does not seem to be crucial in this application of rhOP-1.

Osteogenic protein 1 device stimulates bone healing to hydroxyapaptite-coated and titanium implants

This study evaluated the effects of osteogenic protein 1 (OP-1) placed in a gap around uncoated and hydroxyapatite (HA)-coated implants. Unloaded cylindrical titanium alloy implants were inserted in the femoral condyles of 16 skeletally mature dogs surrounded by a 3-mm gap. The gap around the implants was filled with 325 μg OP-1 in 130 mg bovine collagen type I as carrier (OP-1 device) or collagen carrier alone or left empty. All groups were tested with both HA-coated and uncoated implants, and the animals were sacrificed after 6 weeks. Implant fixation was determined by push-out test. Bone ongrowth and bone formation were evaluated by quantitative histomorphometry. OP-1 device enhanced mechanical fixation of uncoated and HA-coated implants, resulting in a higher shear strength than implants with collagen matrix and control implants. Bone ongrowth and bone formation in the gap were also stimulated 3-fold for OP-1 groups when compared with empty controls, but no difference was found between OP-1 groups and collagen matrix groups. This study suggests that the OP-1 device placed in a gap around uncoated and HA-coated implants is capable of enhancing mechanical fixation and periimplant bone formation. The collagen carrier alone also enhanced bone ongrowth and fixation significantly.