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

AIM 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. MATERIALS AND METHODS 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 12 weeks 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. RESULTS Both MM and LM areas demonstrated an increase in mean RPL following augmentation, 382.6 µm ± 95.1 vs. 290.5 µm ± 79.3 and 335.6 µm ± 94.2 vs. 292.9 µm ± 77.0, respectively (p < .05). There was a significant difference in the numbers of RP per 1 mm 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. CONCLUSION Augmentation with VCMX did not alter the composition of lining and masticatory mucosa at implant sites. CLINICAL RELEVANCE 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

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

Stromal cells associated with soft tissue augmentation by a volume stable collagen matrix (VCMX) are predominated by anti-inflammatory/reparative macrophages

Aim: To define immunophenotypes of stromal inflammatory and endothelial cells and fibroblasts 3-months post-augmentation of the peri-implant soft tissue using a porcine cross-linked collagen matrix (VCMX). Methods: Peri-implant soft tissue samples were obtained from 12 patients at the lining mucosa (LM) - masticatory mucosa (MM) junction, before and at 3-months post-augmentation. Immunohistochemical stains for identification of inflammatory cells [T (CD3) and B (CD20) lymphocytes, plasma cells (CD138)], macrophages (CD68-pro-inflammatory, CD163-anti-inflammatory/reparative), endothelial cells (CD31, CD34) and fibroblasts (CD90, TE-7), were performed. Differences in the mean positively-stained cells pre- and post-augmentation was analyzed by Wilcoxon Signed-Rank Test. Results: CD31+ endothelial cells showed increased mean numbers in MM2 compared to MM1 (p=0.025) and in LM2 compared to LM1 (p=0.047). CD163+ anti-inflammatory macrophages showed mean numbers in MM2 higher than MM1 (p=0.021) and in LM2 than LM1 (p=0.012). All other cell phenotypes showed insignificant changes between pre- and post-augmentation. Conclusion: This molecular study provided novel insight on the frequency of phenotypes of stromal cells in the wound healing process 3-months post-augmentation with VCMX, with anti-inflammatory CD163+ macrophages being predominant. This should be further investigated in order to find novel therapeutic approaches to modulate and promote the VCMX-related healing process