Subcutaneous reactions and degradation characteristics of collagenous and noncollagenous membranes in a macaque model

Modified membrane fixation technique in a severe continuous horizontal bone defect: A case report

BACKGROUND

Continuous severe horizontal bone defect is common in the aesthetic maxillary anterior area, and presents a major challenge in implant dentistry and requires predictable bone augmentation to increase the width of the alveolar bone.

CASE SUMMARY

A 24-year-old man, with a history of well-controlled IgA nephropathy, presented to the Dentistry Department of our hospital complaining of missing his right maxillary anterior teeth 1 mo ago. Severe horizontal alveolar bone defects at sites of teeth 12, 13 and 14 were diagnosed. A modified guided bone regeneration surgical approach stabilizing the absorbable collagen membrane and particulate graft materials by periosteal diagonal mattress suture (PDMS) combined with four corner pins was used for this severe continuous horizontal bone defect. The outcome revealed that the newly formed alveolar ridge dimension increased from 0.72 mm to 11.55 mm horizontally 10 mo postoperatively, with no adverse events. The implant surgery was successfully performed.

CONCLUSION

This case highlights that PDMS combined with four corner pins is feasible to maintain the space and stabilize the graft and membranes in severe continuous horizontal bone defect.

Calvaria Critical Size Defects Regeneration Using Collagen Membranes to Assess the Osteopromotive Principle: An Animal Study

Guided bone regeneration (GBR) is a common practice in implantology, and it is necessary to use membranes in this process. The present study aimed to evaluate the osteopromotive principle of two porcine collagen membranes in critical-size defects at rats calvaria. Ninety-six Albinus Wistar rats were divided into BG (positive control), JS, CS, and CG (negative control) groups and were sacrificed at 7, 15, 30, and 60 days postoperatively. The samples were assessed by histological, histometric, immunohistochemical, and microtomographic analyses. More intense inflammatory profile was seen in the JS and CS groups (p < 0.05). At 60 days, the JS group showed a satisfactory osteopromotive behavior compared to BG (p = 0.193), while CS did not demonstrate the capacity to promote bone formation. At the immunohistochemical analysis, the CS showed mild labeling for osteocalcin (OC) and osteopontin (OP), the JS demonstrated mild to moderate for OC and OP and the BG demonstrated moderate to intense for OC and OP. The tridimensional analysis found the lowest average for the total volume of newly formed bone in the CS (84,901 mm2), compared to the BG (319,834 mm2) (p < 0.05). We conclude that the different thicknesses and treatment techniques of each membrane may interfere with its biological behavior.

Optimizing the bio-degradability and biocompatibility of a biogenic collagen membrane through cross-linking and zinc-doped hydroxyapatite

Biogenic collagen membranes have been widely used as soft tissue barriers in guided bone regeneration (GBR) and guided tissue regeneration (GTR). Nevertheless, their clinical performance remains unsatisfactory because of their low mechanical strength and fast degradation rate in vivo. Although cross-linking with chemical agents is effective and reliable for prolonging the degradation time of collagen membranes, some adverse effects including potential cytotoxicity and undesirable tissue integration have been observed during this process. As a fundamental nutritional trace element, zinc plays an active role in promoting the growth of cells and regulating the degradation of the collagen matrix. Herein, a biogenic collagen membrane was cross-linked with glutaraldehyde-alendronate to prolong its degradation time. The physiochemical and biological properties were enhanced by the incorporation of zinc-doped nanohydroxyapatite (nZnHA), with the native structure of collagen preserved. Specifically, the cross-linking combined with the incorporation of 1% and 2% nZnHA seemed to endow the membrane with the most appropriate biocompatibility and tissue integration capability among the cross-linked membranes, as well as offering a degradation period of six weeks in a rat subcutaneous model. Thus, improving the clinical performance of biogenic collagen membranes by cross-linking together with the incorporation of nZnHA is a promising strategy for the improvement of biogenic collagen membranes. STATEMENT OF SIGNIFICANCE: The significance of this research includes.

[Biodegradation properties of multi-laminated small intestinal submucosa]

OBJECTIVE

To study the biodegradation properties of multi-laminated small intestinal submucosa (mSIS) through in vitro and in vivo experiments, comparing with Bio-Gide, the most widely used collagen membrane in guided bone regeneration (GBR) technique, for the purpose of providing basis to investigate whether mSIS meets the requirements of GBR in dental clinics.

METHODS

The degradation properties were evaluated in vitro and in vivo. In vitro degradation was performed using prepared collagenase solution. Morphology of mSIS and Bio-Gide in degradation solution were observed and the degradation rate was calculated at different time points. In in vivo experiments, nine New Zealand rabbits were used for subcutaneous implantation and were divided into three groups according to observation intervals. Six unconnected subcutaneous pouches were made on the back of each animal and were embedded with mSIS and Bio-Gide respectively. At the end of weeks 4, 8, and 12 after operation, gross observation and HE staining were used to evaluate the degree of degradation and histocompatibility.

RESULTS

In vitro degradation experiments showed that mSIS membrane was completely degraded at the end of 12 days, while Bio-Gide was degraded at the end of 7 days. Besides, mSIS maintained its shape for longer time in the degradation solution than Bio-Gide, indicating that mSIS possessed longer degradation time, and had better ability to maintain space than Bio-Gide. In vivo biodegradation indicated that after 4 weeks of implantation, mSIS remained intact. Microscopic observation showed that collagen fibers were continuous with a few inflammatory cells that infiltrated around the membrane. Bio-Gide was basically intact and partially adhered with the surrounding tissues. HE staining showed that collagen fibers were partly fused with surrounding tissues with a small amount of inflammatory cells that infiltrated as well. Eight weeks after operation, mSIS was still intact, and was partly integrated with connective tissues, whereas Bio-Gide membrane was mostly broken and only a few residual fibers could be found under microscope. Only a small amount of mSIS debris could be observed 12 weeks after surgery, and Bio-Gide could hardly be found by naked eye and microscopic observation at the same time.

CONCLUSION

In vitro degradation time of mSIS is longer than that of Bio-Gide, and the space-maintenance ability of mSIS is better. The in vivo biodegradation time of subcutaneous implantation of mSIS is about 12 weeks and Bio-Gide is about 8 weeks, both of which possess good biocompatibility.

Single-staged implant placement using the bone ring technique with and without membrane placement: Micro-CT analysis in a preclinical in vivo study

OBJECTIVES

To assess the impact of collagen membrane application on bone formation surrounding implants placed simultaneously with the bone ring technique.

MATERIAL AND METHODS

Dental implants were inserted simultaneously with the bone ring technique in standardized, vertical alveolar bony defects in the mandible of dogs. On one side of the mandible, the augmented sites were covered with a collagen membrane (M-Group). On the contralateral side, no membranes were used (NM-Group). Implants were left to heal with osseointegration for three and six months. The harvested samples were analyzed by means of micro-CT.

RESULTS

A nonparametric analysis of data revealed that the membranes were not a significant negative factor for bone volume (BV), but for bone-to-implant contact (BIC, p = .04). Absence of healing caps impaired BV (p = .04) and BIC (p = .02) as well. Furthermore, loss of healing caps and exposure to the oral environment significantly and negatively affected BV (p < .001) and bone mineral density (p < .05) within 2 mm below the implant shoulder. Implant exposure and healing time had a negative interaction effect on both BV (p = .01) and BIC (p = .01).

CONCLUSIONS

Within its limitations, the present study revealed no benefit of membrane application to implant placement simultaneous with the bone ring technique. Disruption of soft tissue healing was identified as a risk factor for decrease in BV and BIC.

Examination of Local Periosteal Microcirculation After Application of Absorbable and Nonabsorbable Membranes

The use of different membranes is common in dentoalveolar surgery. Absorbable and nonabsorbable membranes are used, often beneath the periosteum, to fulfil different functions (as barriers, patches, or spacers). It is still unclear to what extent such membranes affect the biology of the periosteum and what role is played by piezoelectric devices during preparation of the periosteum. We placed two different membranes (absorbable and nonabsorbable) underneath the periosteum of rat calvaria. We prepared the periosteum using different methods (piezoelectric device vs mechanical device). We then examined and analyzed periosteal microcirculation over a period of 28 days. A clear difference was observed between the two methods when used with absorbable membranes: The piezoelectric device offered advantages. Absorbable membranes maintain considerably more local periosteal microcirculation and should be given preference. In addition, we observed an advantage to using a piezoelectric device for periosteal dissection. Therefore, this method should also be used more widely.

Effects of collagen membrane application and cortical bone perforation on de novo bone formation in periosteal distraction: an experimental study in a rabbit calvaria

OBJECTIVES

The aim of the present study was to assess the impact of collagen membrane application and cortical bone perforations in periosteal distraction osteogenesis.

STUDY DESIGN

A total of 32 New Zealand rabbits were randomized into four experimental groups, considering two treatment modalities. Calvarial bone was perforated or left intact (P+/-). In half the animals, the distraction mesh was covered with a collagen membrane (M+/-). All animals were subjected to a 7-day latency period and a 10-day distraction period. The samples were harvested after 4-week and 8-week consolidation periods and analyzed histologically and by means of micro-computed tomography.

RESULTS

Primary, woven bone observed at the 4-week consolidation period was gradually replaced by lamellar bone at the 8-week consolidation period. Significant increase in bone volume was found in all groups (P < .001) and in bone mineral density in groups I (P-/M-; P < .001), III (P+/M-; P < .001), and IV (P+/M+; P = .013). Group III (P+/M-) showed significantly more new bone at the 8-week consolidation period compared with the other three groups (P = .001), with no differences observed in bone mineral density between groups at a given time-point.

CONCLUSIONS

In the present model, cortical bone perforations have more impact on the osteogenic process compared with the application of a collagen membrane.

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

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