Volume-stable Collagen Matrix Research Articles

Volumetric assessment of volume stable collagen matrix in maxillary single implant site development: A randomized controlled clinical trial.

The stability of soft tissue volume around dental implants is an important factor for the final esthetic outcome. The main objective of this study was to compare volume stable collagen matrix (VCMX) versus connective tissue graft (CTG) in the augmentation of soft tissue profiles in single implant sites with a class I Siebert ridge defect. Twenty patients (14 females and 6 males) were enrolled in the present study. After implant placement and augmentation of the buccal defect by VCMX or CTG, post-operative evaluation of the volumetric changes at the augmented implant site was carried out at 3, 6, and 9 months as primary outcome, clinical and radiographic soft tissue thickness were carried out at baseline and 9-month intervals, visual analog scale (VAS) and oral health impact profile-14 (OHIP14) were recorded 2 weeks after the surgery. A statistically significant difference in soft tissue volume was found between baseline and 3, 6, and 9 months postoperatively in both groups with the highest value at 9 months (136.33 ± 86.80) (mm3) in VCMX and (186.38 ± 57.52) (mm3) in CTG. Soft tissue thickness was significantly increased in both groups at 9 months in comparison to baseline. However, there was a significantly higher increase in soft tissue thickness at 9 months in CTG (3.87 ± 0.91) than in VCMX (2.94 ± 0.31). Regarding the radiographic soft tissue thickness, there was a statistically significant increase in both groups at 9 months in comparison to baseline. However, there was a statistically higher increase in the radiographic soft tissue thickness at 9 months in CTG (3.08 ± 0.97) than in VCMX (2.37 ± 0.29). VAS showed a statistically lower value in VCMX (0.4 ± 0.7) than CTG (2.8 ± 1.48). The OHIP recorded lower values in the VCMX group than the CTG group with no statistical significance. In addition, there was no difference in the PES between the two groups. The present study showed that CTG and VCMX were both effective in soft tissue augmentation around implants in the esthetic zone. However, CTG proved more efficient in increasing peri-implant soft tissue volume and mucosal thickness around single implants at a 9-month follow-up period. VCMX was associated with less pain or discomfort and reduced patient morbidity, as reflected by the significantly reduced VAS value in the VCMX group.

Effects of implant placement timingand type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical canine model.

To determine the effects of implant timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical model. Four implant placement protocols were randomly applied at the mesial root sites of the third and fourth mandibular premolars in 10 mongrel dogs: immediate placement (group IP), early placement (group EP), delayed placement with/without alveolar ridge preservation (groups ARP and DP, respectively). A connective-tissue graft (CTG) or porcine-derived volume-stable collagen matrix (VCMX) was applied to enhance the ridge profile (simultaneously with implant placement in group IP and staged for others), resulting in five sites for each combination. All dogs were sacrificed 3 months after soft-tissue grafting. Histological and histomorphometric analyses were performed, and the data were analysed descriptively. CTG and VCMX were difficult to differentiate from the augmented area. The median total tissue thickness on the buccal aspect of the implant was largest in group IP/CTG (between 2.78 and 3.87 mm). The soft-tissue thickness was generally favourable with CTG at all implant placement timings. Within the DP groups, CTG yielded statistically significantly larger total and soft-tissue thickness than VCMX (p < .05). Among the groups with VCMX, group EP/VCMX showed the largest soft-tissue thickness at apical levels to the implant shoulder. CTG generally led to greater tissue thickness than VCMX.

Soft-tissue volume augmentation using a connective tissue graft and a volume-stable collagen matrix with polydeoxyribonucleotide for immediate implant placement: a pilot study in a dog model.

The aims of this study were 1) to investigate the effects of a subepithelial connective tissue graft (SCTG) and a volume-stable collagen matrix (VCMX) on soft-tissue volume gain in the immediate implant placement protocol, and 2) to determine whether polydeoxyribonucleotide (PDRN) can enhance the effects of a VCMX. Dental implants were placed in 4 mongrel dogs immediately after extracting the distal roots of their third and fourth mandibular premolars. The gap between the implant and the buccal bone plate was filled with synthetic bone substitute particles. The following soft-tissue augmentation modalities were applied buccally: 1) control (no augmentation), 2) SCTG, 3) VCMX, and 4) VCMX/PDRN. After 4 months, histomorphometric analysis was performed. Tissue changes were evaluated using superimposed standard tessellation language (STL) files. Wound dehiscence was found in more than half of the test groups, but secondary wound healing was successfully achieved in all groups. Histomorphometrically, tissue thickness was favored in group SCTG at or above the implant platform level (IP), and group SCTG and the groups with VCMX presented similar tissue thickness below the IP. However, the differences in such thickness among the groups were minor. The keratinized tissue height was greater in group VCMX/PDRN than in groups SCTG and VCMX. Superimposing the STL files revealed a decrease in soft-tissue volume in all groups. Wound dehiscence after soft-tissue volume augmentation might be detrimental to obtaining the expected outcomes. PDRN appears not to have a positive effect on the soft-tissue volume gain.

The "HAT-TRICK" technique: A modification of soft tissue grafting using volume stable collagen matrix and cross-linked hyaluronic acid. Part A: The pontic site

Vertical soft tissue augmentation between implants can be clinically challenging and burdensome for patients when employing conventional techniques. Recently, with the introduction of xenogenic collagen matrices, the principle of single-site surgery has become more common. However, some issues persist regarding graft stability and tissue integration. In the present technical note, the authors introduce the “HAT-TRICK” technique to address these observed difficulties. As the name suggests, this technique is believed to provide improved stability, volumetric gain, and histological integration of the implanted matrix by shaping it appropriately resembling a hat over the crest with apical bevels, stabilized with fixation pins and infused with cross-linked hyaluronic acid (xHya). A two-month observation of a bi-maxillary case is presented with detailed description of the technique and digitalized comparison methods for an easier explanation of the introduced technique.

Treatment of single gingival recessions using biofunctionalized collagen matrix: A case series.

Connective tissue graft substitutes have been used widely to overcome autogenous graft limitations. Nevertheless, they do not provide comparable results in the treatment of periodontal and peri-implant soft tissue defects. Based on the principles of tissue-engineered materials, injectable platelet-rich fibrin (i-PRF) has been combined with collagen matrices (CMs) to enhance their clinical efficacy. To the best of our knowledge, this is the first case series demonstrating the use of i-PRF for the biofunctionalization of a volume-stable collagen matrix (VCMX) as an adjunct to coronally advanced flap (CAF) to treat single gingival recession (GR) defects. The study included 10 patients. Bleeding on probing, probing depth, GR height, clinical attachment level, esthetics, and dentin hypersensitivity were evaluated. After 6 months, a significant GR reduction (RecRed: 2.15 ± 0.7mm; p = 0.005) and percentage of root coverage (% RC) of 81.13% were observed. Additionally, 40% of the sites showed complete root coverage. Gingival thickness increased 0.64mm. Patient-centered evaluations demonstrated dentin hypersensitivity and esthetics improvements by the end of follow-up. VCMX biofunctionalized with i-PRF associated with CAF technique showed promising clinical outcomes in the treatment of single RT1 GR defects.

Harvest graft substitute for soft tissue volume augmentation around existing implants: A randomized, controlled and blinded multicenter trial.

Using a single-blind, randomized, controlled, multicenter, practice-based clinical trial, a volume-stable collagen matrix (VCMX) was compared with connective tissue graft (CTG) for soft tissue augmentation around existing dental implants. Sixty patients (31 VCMX and 31 CTG) were included. The primary outcome was a soft tissue thickness change 3mm below the gingival margin (GM). Secondary outcomes included clinical measures, such as keratinized tissue widths (KTw), probing pocket depths, and pink esthetic scores, and patient-reported outcomes (PRO). There were no significant differences between test and control patient demographics or clinical measures throughout the 1-year study. VCMX "grafts" were by design larger than CTG, and surgery time was less (27% less, p=0.0005). Three millimeters below the GM (primary endpoint), tissue thickness increase was noninferior for VCMX compared with CTG (0.93±0.80mm vs. 1.10±0.51mm, respectively), inferior (by 0.25mm) at 1mm, and noninferior at 5mm. Postoperative pain was significantly less for VCMX patients (p<0.0001), but all other PRO measures, including esthetics and satisfaction, improved similarly for both therapies. Given the inclusion criteria for this study, namely soft tissue augmentation around existing implants with some evidence of KTw and minimal recession, VCMX provided soft tissue thickness and volume increases similar (noninferior) to CTG. Clinical measures and PRO were similar between therapies-site sensitivity and esthetics improved similarly for both therapies-but surgery time and pain following surgery were significantly less for VCMX.

In Vitro Investigation of Gelatin/Polycaprolactone Nanofibers in Modulating Human Gingival Mesenchymal Stromal Cells.

The aesthetic constancy and functional stability of periodontium largely depend on the presence of healthy mucogingival tissue. Soft tissue management is crucial to the success of periodontal surgery. Recently, synthetic substitute materials have been proposed to be used for soft tissue augmentation, but the tissue compatibility of these materials needs to be further investigated. This study aims to assess the in vitro responses of human gingival mesenchymal stromal cells (hG-MSCs) cultured on a Gelatin/Polycaprolactone prototype (GPP) and volume-stable collagen matrix (VSCM). hG-MSCs were cultured onto the GPP, VSCM, or plastic for 3, 7, and 14 days. The proliferation and/or viability were measured by cell counting kit-8 assay and resazurin-based toxicity assay. Cell morphology and adhesion were evaluated by microscopy. The gene expression of collagen type I, alpha1 (COL1A1), α-smooth muscle actin (α-SMA), fibroblast growth factor (FGF-2), vascular endothelial growth factor A (VEGF-A), transforming growth factor beta-1 (TGF-β1), focal adhesion kinase (FAK), integrin beta-1 (ITG-β1), and interleukin 8 (IL-8) was investigated by RT-qPCR. The levels of VEGF-A, TGF-β1, and IL-8 proteins in conditioned media were tested by ELISA. GPP improved both cell proliferation and viability compared to VSCM. The cells grown on GPP exhibited a distinct morphology and attachment performance. COL1A1, α-SMA, VEGF-A, FGF-2, and FAK were positively modulated in hG-MSCs on GPP at different investigation times. GPP increased the gene expression of TGF-β1 but had no effect on protein production. The level of ITG-β1 had no significant changes in cells seeded on GPP at 7 days. At 3 days, notable differences in VEGF-A, TGF-β1, and α-SMA expression levels were observed between cells seeded on GPP and those on VSCM. Meanwhile, GPP showed higher COL1A1 expression compared to VSCM after 14 days, whereas VSCM demonstrated a more significant upregulation in the production of IL-8. Taken together, our data suggest that GPP electrospun nanofibers have great potential as substitutes for soft tissue regeneration in successful periodontal surgery.

Treatment of Maxillary Gingival Recessions Using the Modified Coronally Advanced Tunnel Technique in Combination with a Volume-Stable Collagen Matrix: A Prospective Case Series with a 12-Month Follow-up

The aim of this case series was to evaluate the clinical performance of a new volume-stable collagen matrix (VCMX) in combination with the modified coronally advanced tunnel technique (MCAT) for the treatment of gingival recessions. Thirteen patients with a total of 33 maxillary RT1 single and multiple gingival recessions were included in the study. Probing pocket depth (PPD), recession width (RECW), recession depth (REC), height of keratinized tissue (HKT), and gingival thickness (GT) were assessed at baseline and at the 12-month follow-up. Postoperative healing was uneventful in all cases without any complications. At 12 months, mean root coverage (MRC) was 92.88%, with complete root coverage (CRC) in 87.88% of treated sites. The present findings suggest that VCMX in combination with MCAT results in predictable coverage of maxillary RT1 gingival recessions. Further studies with larger sample sizes and control groups are needed to support these preliminary outcomes.

A new volume-stable collagen matrix (VCMX) to treat single gingival recession associated with partially restored non-carious cervical lesions: a case series.

Collagen matrixes have been developed as possible connective tissue graft substitutes to overcome patient discomfort, undesired palatal healing, and the limited amount of donor tissue. The aim of this case series is to assess a coronally advanced flap (CAF) with a new volume-stable collagen matrix (VCMX) to treat single gingival recession (GR) associated with partially restored non-carious cervical lesions (NCCL). Twelve patients diagnosed with single GR RT1 + NCCL (B+) were included in this study and received a restorative - partial resin composite with apical margin 1 mm beyond the estimated cementoenamel junction (CEJ) - and a surgical approach - CAF+VCMX. Clinical and patient-centered assessments were recorded at baseline and 6 months postoperatively from ten patients. Significant recession reduction (RecRed:2.1mm), clinical attachment level gain (CAL:1.34mm), and combined defect coverage (CDC) of 51.67% were observed at 6 months. The estimate root coverage (RC) was 69.48%, obtained using the estimated CEJ. No difference in keratinized-tissue width (KTW) was observed over time. A gain in gingival thickness (GT) of 0.42 mm was observed after 6 months (p=.002) and an improvement in patient satisfaction due to better esthetics (p<.001). Within the present study's limits, CAF plus VCMX provided significant improvement in treating single GR combined with partially restored NCCL (B+).

Coronally Advanced Flap with Xenogeneic Collagen Matrix for the Treatment of Gingival Recessions at Sites Presenting with Cervical Restorations or Noncarious Cervical Lesions: A Clinical and Ultrasonographic Study.

The aim of this prospective study was to evaluate the efficacy of a cross-linked xenogeneic volume-stable collagen matrix (CCM) in treating gingival recessions (GRs) at teeth presenting with cervical restorations or noncarious cervical lesions (NCCLs). Fifteen patients with esthetic concerns for multiple sites with GRs and cervical restorations were consecutively enrolled. The sites were treated with a coronally advanced flap (CAF) design in combination with a CCM. When present, the previous restoration was removed, and the cementoenamel junction was reconstructed with a composite material. The CCM was stabilized on the root surface(s) previously occupied by the restoration. The CAF was sutured to completely cover the graft. Clinical measurements and intraoral digital and ultrasonographic scans were collected at baseline and at 3 and 6 months postsurgery. Limited postoperative discomfort was reported by patients during the healing. The mean root coverage at 6 months was 74.81%. Average increases in gingival thickness of 0.43 mm and 0.52 mm were observed when measured with ultrasonography 1.5 mm and 3 mm apical to the gingival margin, respectively (P < .05). Relatively high patient-reported satisfaction and esthetics were associated with the treatment outcomes. The treatment resulted in a significant reduction in dental hypersensitivity (mean: 33 VAS points). The present study demonstrated that CAF + CCM is an effective approach for treating GRs at sites with cervical restorations or NCCLs. Int J Periodontics Restorative Dent 2023;43:147-154. doi: 10.11607/prd.6448.

Stromal Cells Associated with Soft Tissue Augmentation by a Volume-Stable Collagen Matrix (VCMX) Are Predominated by Anti-inflammatory/Reparative Macrophages.

This article defines immunophenotypes of stromal inflammatory and endothelial cells and fibroblasts 3 months after augmentation of the peri-implant soft tissue using a porcine cross-linked collagen matrix (VCMX). Peri-implant soft tissue samples were obtained from 12 patients at the lining mucosa (LM)-masticatory mucosa (MM) junction before (1) and 3 months after (2) augmentation. Immu- nohistochemical stains were performed to identify inflammatory cells (T [CD3] and B [CD20] lym- phocytes, plasma cells [CD138]), macrophages (CD68-proinflammatory, CD163-anti-inflammatory/ reparative), endothelial cells (CD31, CD34), and fibroblasts (CD90, TE-7). Differences in the mean positively stained cells pre- and postaugmentation were analyzed by Wilcoxon signed-rank test. CD31&#43; endothelial cells showed increased mean numbers in MM2 compared to MM1 (P &#61; .025) and in LM2 compared to LM1 (P &#61; .047). CD163&#43; anti-inflammatory macrophages showed higher mean numbers in MM2 than in MM1 (P &#61; .021) and in LM2 than in LM1 (P &#61; .012). All other cell phenotypes showed nonsignificant changes between pre- and postaugmentation. This molecular study provides novel insight on the frequency of stromal cell phenotypes in the wound healing process at 3 months postaugmentation with VCMX, with anti-inflammatory CD163&#43; macrophages being predominant. This should be further investigated to help find novel therapeutic approaches to modulate and promote the VCMX-related healing process.

Soft tissue augmentation with a volume-stable collagen matrix or an autogenous connective tissue graft at implant sites: Five-year results of a randomized controlled trial post implant loading.

Interventions to augment the mucosal thickness around dental implants are indicated to optimize esthetics and maintain peri-implant health. However, there is a lack of clinical data on the long-term performance of soft tissue substitutes, such as volume-stable collagen matrix (VCMX), compared to autogenous grafts, such as subepithelial connective tissue grafts (SCTGs). This randomized controlled trial aimed to assess 5-year data on clinical and radiographic outcomes at implant sites previously augmented with VCMX or SCTG. Twenty patients were randomly assigned for soft tissue augmentation with VCMX or SCTG at single implant sites. Following abutment connection, final restorations were inserted (baseline; BL) and patients were reexamined up to 5 years (FU-5). Measurements included clinical data, marginal bone levels, mucosal thickness, and ridge contour changes. Nonparametric tests and estimates were applied for the statistical analysis. The median buccal mucosal thickness increased by 0.3mm (Q1: -0.8; Q3: 1.0) in the VCMX group (P=0.656) and 0.3mm (Q1: 0.0; Q3: 1.0) in the SCTG group (P=0.188) between BL and FU-5 (intergroup P=0.752), while the ridge contour decreased by a median of -0.3mm (-0.9; -0.1) (P=0.078) for VCMX and -0.3mm (-0.4; -0.2) (P=0.039) for SCTG (intergroup P=0.817). Peri-implant health was maintained in both groups with stable clinical and radiographic outcomes and without significant differences between the treatments. Despite the limited power and considerable dropout rate in the present study, soft tissue augmentation at implant sites with either VCMX or SCTG resulted in similar stable peri-implant tissues, favorable esthetics, and clinically negligible contour changes at 5 years post loading.

Contour Changes Following Implant Placement and Concomitant Soft Tissue Augmentation Applying a Volume-Stable Collagen Matrix.

The objective of this study was to assess volumetric and linear changes of buccal mucosal thickness at implant sites following soft tissue augmentation with a volume-stable collagen matrix (VCMX). Soft tissue augmentation using a VCMX was performed in 12 patients at the time of implant placement. Hydrocolloid impressions were taken prior to surgery and at 1 and 6 months postsurgery. Stone cast models were scanned, and stereolithography (STL) files from the three time points were uploaded to an image-analysis software. At all time points, linear and volumetric measurements of the contour changes up to 3 mm apical to the mucosal margin were performed and were analyzed statistically. At 1 mm apical to the mucosal margin, the change in soft tissue thickness between presurgery (T1) and 1 month (T2) amounted to 0.21 ± 1.22 mm, and the change between T1 and 6 months (T3) was 0.08 ± 1.47 mm. At 3 mm apical to the mucosal margin, the change in soft tissue thickness was 1.92 ± 1.70 mm between T1 and T2 and 0.31 ± 1.26 mm between T1 and T3. Contour (volumetric) changes revealed an increase of 0.58 ± 0.73 mm between T1 and T2 and an overall gain of 0.55 ± 0.73 mm between T1 and T3. Soft tissue augmentation with VCMX increased the ridge profile. The increase in ridge width was greater at 3 mm below the ridge crest than at 1 mm below the ridge crest. Remodeling processes during healing showed a decrease in the ridge contour between 1 and 6 months.

A Minimally Invasive Approach for the Treatment of Multiple Adjacent Gingival Recessions with a Volume-Stable Collagen Matrix: A Case Series

Several soft tissue graft materials have been utilized over the years as alternatives to the autogenous connective tissue graft for reducing patient morbidity. In particular, a novel volume-stable xenogeneic collagen matrix (VXCM) has recently been introduced for soft tissue augmentation at implant sites. The VXCM is porous in nature, and its mechanical properties suggest utilizing a specific flap approach when treating multiple adjacent gingival recessions (MAGRs). Herewith, a minimally invasive surgical technique is described in combination with VXCM for treatment of MAGRs. Five patients with 16 MAGRs were treated with this approach. All sites healed uneventfully, and patients reported minimal discomfort. At 6 months, the technique resulted in a mean root coverage of 94.73%, and complete root coverage was achieved in 13 sites (81.25%). The proposed minimally invasive approach may have potential to enhance flap blood supply and graft vascularization, promoting rapid healing with minimal postoperative discomfort. In addition, this approach can result in satisfactory clinical, esthetic, and patient-reported outcomes. Future adequately powered clinical trials are needed to validate the findings of this preliminary report.

Clinical and patient-reported outcomes after recession coverage using modified vestibular incision subperiosteal tunnel access with a volume-stable collagen matrix as compared to a coronally advanced flap with a subepithelial connective tissue graft.

Coronally advanced split-or full-thickness (CAST or CAFT) flaps in combination with subepithelial connective tissue grafts (SCTGs) are commonly used in root-coverage procedures despite postoperative pain and bleeding from the graft donor site. Therefore, the modified vestibular incision subperiosteal tunnel access procedure (VISTAX) uses a novel collagen matrix (VCMX) instead of autogenous tissue to address the limitations associated with autogenous tissue grafting. This retrospective study compared the clinical outcomes of VISTAX to the results obtained after using a CAST or CAFT flap in combination with SCTG for root coverage. Patients with single or multiple adjacent recession I/II defects were included, with 10 subjects each in the VISTAX, CAFT, and CAST groups. Defect coverage, keratinized tissue width, esthetic scores, and patients' perceived pain and dentinal hypersensitivity (visual analogue scale [VAS]) were assessed at baseline, 3 months, and 6 months. All surgical techniques significantly reduced gingival recession (P<0.0001). Defect coverage, esthetic appearance, and the reduction in dentinal hypersensitivity were comparable. However, the VAS scores for pain were significantly lower in the VISTAX group than in the CAFT and CAST groups, which had similar scores (P<0.05). Furthermore, the clinical results of VISTAX and CAFT/CAST generally remained stable at 6 months. The clinical outcomes of VISTAX, CAFT, and CAST were comparable. However, patients perceived significantly less pain after VISTAX, indicating a potentially higher patient acceptance of the procedure. A prospective trial with a longer follow-up period and a larger sample size should therefore evaluate VISTAX further.

Efficacy of a harvest graft substitute for recession coverage and soft tissue volume augmentation: A randomized controlled trial.

The autogenous connective tissue graft (CTG) with coronally advanced flap (CTG+CAF) is the "gold standard" for recession defect coverage; however, researchers continue to pursue lower morbidity, more convenient and unlimited supply harvest graft substitutes, including those that could provide soft tissue volume augmentation. A randomized, controlled, double-masked comparison of a volume-stable collagen matrix (VCMX) versus CTG was conducted at four clinical investigation sites. Single, contralateral, within patient matched-pair, RT1 recession defects were treated with VCMX+CAF (test) and CTG+CAF (control). The primary efficacy end point was percent root coverage at 6 months. Secondary efficacy end points included clinical measures such as soft tissue volume, attachment level, and keratinized tissue width. Patient-reported outcomes included measures such as discomfort, esthetics, and overall satisfaction; 6-month end point results were followed for 1 year. Thirty patients received control and test therapies, and all patients were available for follow-up measures. Average percent root coverage for CTG+CAF was 90.5% ± 14.87%versus 70.7% ± 28.26% for VCMX+CAF, P<0.0001. Both therapies produced significant soft tissue volume increases (84.8 ± 47.43 mm3 control versus 48.90 ± 35.58 mm3 test, P=0.0006). The test, harvest graft substitute produced less postoperative pain and was preferred by patients at the 6-month end point. All other end point measures were not significantly different. VCMX+CAF root coverage was inferior to CTG+CAF but produced less morbidity and was preferred by patients. Case/patient selection and surgical technique appear key to achieving successful results with the harvest graft alternative.

Peri-implant tissue augmentation by volume-stable collagen matrix transplantation: a study of dog mandibles.

The aim of this study was to investigate histologically the amount of peri-implant tissue augmentation after volume-stable porcine collagen matrix transplantation. Six male beagle dogs were used in the experiment. P2, P4, and M1 distal roots were extracted under general anesthesia. After 6months, implants were placed in the same sites, and volume-stable porcine collagen matrix transplantation was performed. Impressions were taken at 1 and 2weeks and at 1, 2, and 3months after transplantation. The dogs were euthanized at 3months, and their mandibles were removed and scanned using micro-computed tomography. Standard Triangulated Language data were also obtained. Using preoperative models as a reference, the data for all time points were compared, and changes in the thickness of the cross-section of the implant sites were measured. The model created at 3months was then compared with the mandible data, and the thickness of collected peri-implant soft tissue was measured under optical microscopy. Increased thickness was found at some of the sites on the buccal side. Regarding the peri-implant soft tissue, the thickness of the measured sites on the buccal side was significantly increased at 3months in the experimental group. Histological observations of the internal structures of the tissue in the experimental group revealed irregular collagen fibers and a remnant collagen matrix. Endogenous tissue was observed within the collagen matrix, indicating good fusion with the surrounding autologous tissue. These results suggest that volume-stable porcine collagen matrix transplantation promotes peri-implant tissue augmentation on the buccal side.

Osteoconductive Properties of a Volume-Stable Collagen Matrix in Rat Calvaria Defects: A Pilot Study.

Volume-stable collagen matrices (VSCM) are conductive for the connective tissue upon soft tissue augmentation. Considering that collagen has osteoconductive properties, we have investigated the possibility that the VSCM also consolidates with the newly formed bone. To this end, we covered nine rat calvaria circular defects with a VSCM. After four weeks, histology, histomorphometry, quantitative backscattered electron imaging, and microcomputed tomography were performed. We report that the overall pattern of mineralization inside the VSCM was heterogeneous. Histology revealed, apart from the characteristic woven bone formation, areas of round-shaped hypertrophic chondrocyte-like cells surrounded by a mineralized extracellular matrix. Quantitative backscattered electron imaging confirmed the heterogenous mineralization occurring within the VSCM. Histomorphometry found new bone to be 0.7 mm2 (0.01 min; 2.4 max), similar to the chondrogenic mineralized extracellular matrix with 0.7 mm2 (0.0 min; 4.2 max). Microcomputed tomography showed the overall mineralized tissue in the defect to be 1.6 mm3 (min 0.0; max 13.3). These findings suggest that in a rat cranial defect, VSCM has a limited and heterogeneous capacity to support intramembranous bone formation but may allow the formation of bone via the endochondral route.

Histologic composition of marginal mucosal tissue augmented by a resorbable volume-stable collagen matrix in soft tissue thickening procedures in humans: a morphometric observational study.

This study aims to examine the composition of lining and masticatory mucosa at the pre- and post-soft tissue augmentation procedures with a volume-stable cross-linking collagen matrix (VCMX) in humans. In 12 patients, single implant sites were augmented with a VCMX. Biopsies were obtained including masticatory (MM) and lining (LM) mucosa before augmentation and at 12weeks post-augmentation procedures. Rete pegs density (RPD), length (RPL), and blood vessel density (BVD) were histomorphometrically analyzed at both time points. Picrosirius red staining under polarized light microscopy was used to evaluate collagen fiber organization. The effects of time and tissue type were evaluated by ANOVA with repeated measures. Both MM and LM areas demonstrated an increase in mean RPL following augmentation, 382.6µm ± 95.1 vs. 290.5µm ± 79.3 and 335.6µm ± 94.2 vs. 292.9µm ± 77.0, respectively (p < .05). There was a significant difference in the numbers of RP per 1mm length (RPD) between the MM (9.2 ± 1.7) and LM (6.1 ± 2.8) mucosa but not between the pre- and post-VCMX augmentation time points. The mean BVD in the LM was greater than in the MM (5.5 ± 2.4 and 6.3 ± 2.4 vs. 3.4 ± 3.3 and 3.7 ± 1.8, respectively, p < .05) but not between time points. The collagen fiber arrangements pre- and post-augmentation were not significantly different. Augmentation with VCMX did not alter the composition of lining and masticatory mucosa at implant sites. A thick soft tissue phenotype around the implant neck is an important factor to maintain peri-implant health. A non-autogenous cross-linking collagen matrix is proposed as an alternate graft substitute in soft tissue augmentation procedures in order to improve implant soft tissue phenotype.

Buccal Pedicle Flap Combined With Porcine Collagen Matrix: A Follow‐Up of 2 Years on 40 Consecutive Cases

A thick peri-implant mucosa is of importance to prevent recession, color alterations, bone remodeling and promote "creeping attachment." A volume stable porcine cross-linked collagen matrix has been recently introduced for soft tissue regeneration and volume maintenance. The aim of this study was to investigate peri-implant soft tissue healing and stability on 40 consecutive patients treated with buccal pedicle flap combined with the use of the collagen matrix. The buccal pedicle flap combined with a volume stable collagen matrix was executed at second stage surgery. The average initial mucosa thickness was 1.32 mm whereas the average band of keratinized mucosa was 1.65 mm and the height 1.3 mm. Four months after surgical procedure and before delivering the final restoration, the peri-implant soft tissue measurements were significantly increased: the average band of keratinized mucosa was 5.10 mm, the mucosa thickness was 3.27 mm, and the mucosa height was 3.32 mm. After 2 years of follow-up, the superimposition of 3D models described an overall volumetric stability of the augmented mucosa with no signs of soft tissue collapse. The proposed modified buccal pedicle flap was demonstrated to perform well in terms of decreased morbidity, maintenance of blood supply, stabilization of the pedicle, superior haemostasis, and speed of treatment. No significant variations of the keratinized tissue were registered when the buccal pedicle flap was executed in conjunction with the collagen matrix that however provided color match with the surrounding tissue as well as an increased mucosa thickness.