Ossification and Bone Regeneration in a Canine GBR Model, Part 2: Glycated Cross-Linked Collagenated Alloplastic Hydroxyapatite Scaffold vs Non-Cross-Linked Collagenated Xenographic Bone Hydroxyapatite.

PURPOSE: To compare bone substitutes composed of glycated collagen with synthetic micro-sized (1 to 10 µm) hydroxyapatite (OB) vs non-cross-linked collagen matrix with large-particle (250 to 1,000 µm) bovine-derived hydroxyapatite (BOC). MATERIALS AND METHODS: The P1 to P4 premolars were bilaterally extracted from the mandibles of 19 Beagle dogs. After 21 days, osteotomies were created in each dog that received OB or BOC and were covered with a collagen membrane or were left untreated. The animals were randomly divided into three groups based on sacrifice time (4, 12, or 24 weeks). The right and left hemimandibles were trimmed to facilitate imaging and histology, and all tissues were placed in 10% neutral-buffered formalin. Microcomputed tomography (MicroCT 40 Scanner, Scanco) was used to analyze bone sections. Bone volume, residual material volume, and bone mineral density were determined for each treatment site (OB and BOC) based on a volume of interest that encompassed the original defect. Additionally, blinded histopathologic assessment (based on the ISO 10993-6 scoring system) and histomorphometry were performed on sections ground to < 100 µm thick and stained with Stevenel's blue. RESULTS: No clinical side effects were noted. No statistical differences were observed for OB vs BOC regarding the mineral volume percentage. Compared to OB, BOC had significantly higher mean mineralization densities at 12 weeks (P < .01), but this difference did not extend to 24 weeks. For residual grafting material, bone maturation, alveolar ridge restoration, and inflammatory response, OB showed a residual amount of bone graft and no statistical differences compared to BOC. CONCLUSION: Both OB and BOC represent valid treatment options for critically sized bone defects. Both bone fillers outperformed the sham-operated, ungrafted (empty) control, demonstrating statistically improved bone growth and ridge restoration.

Ossification and Bone Regeneration in a Canine GBR Model, Part 1: Thick vs Thin Glycated Cross-Linked Collagen Devices.

Purpose: To compare glycated multilayered membranes (OV) to a commercially available thin-layer membrane (OP) in a lateral ridge augmentation model in dogs. Materials and Methods: This was designed as a three-arm study, where one negative control (empty defect) was compared to two test arms: alveolar bone defects grafted with a mixture of 90% deproteinized bovine bone mineral and 10% porcine collagen, then covered with either a thick- (OV) or thin-layered (OP) membrane. Animals were randomly divided into three groups corresponding to the final sacrifice times of 4 weeks, 12 weeks, and 24 weeks. Sections underwent microCT, histology, histopathology, and histomorphometry. Results: No statistical differences were observed for OV compared to OP regarding the percentage of mineral volume and mean mineral density, amount of bone maturation, percentage of bone graft and membrane remaining in the grafted area, alveolar ridge width measurements, membrane mineralization, or ossification. Test groups presented significantly higher values compared to the empty control for all the endpoints. Conclusions: Within its limitations, this in vivo study highlighted that multilayered thick glycated membranes can serve as effective occlusive barriers for up to 6 months.

Ossification of a collagen membrane cross-linked by sugar: a human case series.

BACKGROUND: Collagen membranes cross-linked by glycation (GLYM) for guided bone regeneration (GBR) and guided tissue regeneration (GTR) are used extensively with proven safety and efficacy. Complete GLYM ossification, when placed in contact with bone, was described in a canine jaw model, suggesting that GLYM may serve as an ossification substrate. The purpose of this case series was to histologically evaluate GLYM in GBR procedures in humans. METHODS: We retrospectively selected seven consecutive patients with implant-related bony defects who underwent GBR with GLYM. Six defects had bone grafts, and one had a barrier alone. Selection criteria were primary closure upon post-surgical examination and tissue that was 2- to 3-mm thick over the implant's cover screw. Tissue was removed when the implants were uncovered after 20 to 29 weeks. Decalcified sections were stained and analyzed under light microscopy. RESULTS: In five of seven specimens, GLYM was identified and preserved its barrier effect. The mean membrane thickness was 0.17 +/- 0.054 mm. In two cases, the bone grafts under the membrane were embedded in new bone, whereas in five cases, they were embedded in fibrous connective tissue. Formation of new dense bone was observed along the side of the membrane facing the original bone, and various degrees of membrane ossification were evident in all five cases. CONCLUSIONS: GLYM maintained its barrier effect in five of seven cases for 25 weeks and induced dense new bone along its interface with underlying tissues. To the best of our knowledge, this is the first report on GLYM ossification in humans with direct mineral apposition on glycated collagen and suggests a new concept of tissue-integrated active barriers.

Skin test hypersensitivity study of a cross-linked, porcine collagen implant for aesthetic surgery.

BACKGROUND: The use of bovine collagen implants for dermal contour correction is associated with a 3% to 5% incidence of hypersensitivity, which necessitates pretreatment screening by an intradermal skin test. OBJECTIVE: The objective was to determine the incidence of hypersensitivity with the recently developed cross-linked, porcine collagen implant, EVOLENCE (ColBar LifeScience Ltd.), which is used intradermally for correction of rhytids and scars. MATERIALS AND METHODS: Enrolled subjects (n=530) received an intradermal injection of 0.1 mL EVOLENCE implant in the left forearm and a second injection in the right forearm after 2 weeks. Injection sites were assessed clinically at 30 minutes and 72 hours after each injection and at 30 days after the second injection. Serum anticollagen antibody determinations were performed at screening and at the end of the study. RESULTS: Study assessments were completed by 519 subjects. No significant erythematous reactions suggestive of positive hypersensitivity were observed. Most subjects did not display antibodies against porcine Type I collagen at any time, and those who did showed no changes in levels during the study. The single-sided 95% upper confidence limit for the possibility of moderate-to-severe erythematous reactions with the EVOLENCE implant was determined as 0.58% of subjects. CONCLUSION: Because the EVOLENCE implant has a low potential for hypersensitivity, intradermal skin testing before its use appears unnecessary.

Long-term efficacy of a novel ribose-cross-linked collagen dermal filler: a histologic and histomorphometric study in an animal model.

BACKGROUND: Degradation and loss of the three-dimensional shape are the major causes of limited functional longevity of dermal fillers made of natural polymers as collagen and hyaluronic acid. OBJECTIVE: This study assessed the functional longevity of a new ribose-cross-linked collagen filler during 24 months in an animal model. METHODS: Ribose-cross-linked collagen (Evolence, Colbar Life Sciences Ltd), glutaraldehyde-cross-linked collagen (Zyplast, Inamed Inc.), and non-cross-linked collagen (Zyderm, Inamed Inc.) were injected in the rabbit ear dermis. Biopsies obtained at 1, 6, 12, and 24 months were histomorphometrically assessed for shape preservation and cell repopulation. RESULT: The three-dimensional shape of Evolence remained stable during 24 months. Zyderm and Zyplast lost their three-dimensional shape after 6 months. Although the cell density in Evolence remained stable over time, that in Zyplast and Zyderm decreased significantly at 12 and 24 months. CONCLUSION: Ribose-cross-linked collagen is endowed with a higher functional longevity as assessed in an animal model when compared with the most used collagen-based dermal fillers.

A two-stage phase I trial of Evolence30 collagen for soft-tissue contour correction.

BACKGROUND: The ideal dermal filler should be nonpermanent but with a durable effect lasting between 1 and 2 years, which is not the case with the resorbable fillers that are currently available. Evolence30 is a new, porcine-derived collagen gel based on the Glymatrix cross-linking technology, which results in a more natural and longer-lasting collagen product. METHODS: In this first clinical trial of Evolence30 (30 mg/ml), the safety and efficacy of this new filler were tested and compared with those of Zyplast (bovine cross-linked) collagen, after treatment of nasolabial folds in 12 volunteers. Safety assessments included two hypersensitivity tests, physical examination of injections sites, punch biopsies for histopathology, adverse events, and blood sample analysis. The seven-grade, validated Modified Fitzpatrick Wrinkle Scale was used by three independent blinded assessors to evaluate efficacy. RESULTS: No treatment-related adverse events were reported. Only transient erythema was observed in both treated sides, and there were no abnormal laboratory findings. None of the sera contained immunoglobulin (Ig) M, IgA, or IgE antibodies against porcine collagen at any time during the study. Initially, Evolence30 and Zyplast improved wrinkle severity to a similar extent. However, in an average follow-up of 18 months, assessment by the blinded assessors showed that the treatment effect on the Evolence30-treated side was superior in 9 of the 11 participants who were treated (p = 0.022). CONCLUSIONS: Evolence30 is a new, porcine-derived collagen product based on the Glymatrix cross-linking technology that enables a safe and effective correction of the nasolabial folds. This correction lasts significantly longer than that with Zyplast.

Ossification of a novel cross-linked porcine collagen barrier in guided bone regeneration in dogs.

BACKGROUND: Collagen membranes for guided bone regeneration (GBR) and guided tissue regeneration (GTR) are used extensively as bioabsorbable barriers. Cross-linking of collagen increases its biodurability and enables the control of its degradation kinetics and barrier function. A novel cross-linking technology was used to produce a porcine type I collagen membrane (GLYM). The purpose of this study was to evaluate the safety, efficacy, and degradation kinetics of GLYM compared to a non-cross-linked bilayer type I and III porcine collagen membrane (BCM) in surgically created defects in dogs. METHODS: After tooth extraction, two mandibular bilateral critical size defects were created in 12 beagle dogs that were randomly assigned to one of five groups: GLYM + bovine bone mineral (BBM), BCM + BBM, BBM alone, sham-operated, or GLYM alone. Dogs were euthanized after 8, 16, and 24 weeks, and sites were prepared for qualitative, semiquantitative, and quantitative light microscopy analyses. RESULTS: Membrane-protected sites displayed bone filling between the BBM particles with almost complete restoration of the original ridge morphology that increased with time up to 16 weeks and remained unchanged at 24 weeks. Both membranes showed marked degradation within 16 to 24 weeks, with BCM inconsistency that was undetectable in one of four sites at 8, 16, and 24 weeks. Membrane ossification was observed in all GLYM sites and in only one BCM site, which progressed with time to 24 weeks. Bone increased by approximately 1 mm on the lingual side, where the GLYM membrane was in direct contact with bone. CONCLUSIONS: Both membranes were safe and effective in supporting bone regeneration in critical size alveolar ridge defects in dogs and completely degraded within 24 weeks with marked BCM inconsistency. In areas of direct contact with bone, all GLYM sites were progressively ossified with time and augmented the original alveolar ridge. To the best of our knowledge, this is the first report of complete ossification of a collagen barrier membrane in GBR procedures.