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.

Oral manifestations associated with inherited hyperhomocysteinemia: A first case description.

Hyperhomocysteinemia is a rare disease caused by nutritional deficiencies or genetic impairment of cysteine metabolism. To date, no oral manifestations of hyperhomocysteinemia have been described in humans. Therefore, to our knowledge, the present case report is the first description of a hyperhomocysteinemic patient showing oral tissue alterations leading to both early tooth loss and failed implant osseointegration. The patient presented with a methylenetetrahydrofolate reductase gene mutation (677T polymorphism) leading to mild hyperhomocysteinemia. The radiologic analysis showed hyperdense lesions scattered in the maxillae. The histologic observations indicated alterations in both collagen and elastic networks in the gingiva and dermis. Interestingly, the presence of ectopic mineralized inclusions was noted in both periodontal ligament and gingiva. Strong osteoclastic activity was associated with abnormal calcification of trabecular spaces. Uneven oral tissue remodeling due to high tissue levels of homocysteine could explain the pathologic manifestations observed in this case.

Poor Biointegration of Porcine Acellular Dermal Matrix Associated with Unfavorable Gingival Healing: A Report of Three Cases.

AIM: The aim of the present work was to explain the poor biointegration of acellular dermal xenogeneic matrix, leading to an unfavorable gingival healing following a grafting procedure for the treatment of soft tissue deficiencies. BACKGROUND: Numerous works have demonstrated the successful use of acellular dermal matrix (ADM) in soft tissue augmentation procedures. However, spare human investigations reported adverse healing outcomes at microscopic level. CASE DESCRIPTION: Three patients showing various soft tissue deficiencies (recession, gingival thickening) requiring a gingival augmentation were grafted using an ADM porcine acellular dermal matrices (pADM) as a soft tissue substitute. For this purpose, appropriate soft tissue augmentation surgeries were performed and the grafted pADM was left for proper healing. Biopsies were harvested from two out of the three patients, respectively, at 11 and 27 weeks in order to conduct a histological evaluation of the pADM's doubtful biointegration. Moreover, the ultrastructural analysis of pADM was performed using scanning electron microscopy, and additional histological procedures were used to assess its ability to support human gingival fibroblast cultures. Signs of gingival inflammation persisted several months postoperatively. Histologically, numerous inflammatory cells characterized the grafted site. Indeed, the high number of foreign body giant cell granulomas and the very densified newly formed collagen fibers highlighted a fibrotic process within gingival connective tissue. The ultrastructural and histological analysis showed that pADM was characterized by very thick and dense collagen bundles demonstrating a nonphysiological collagen network organization. Cell culture experiments showed fibroblasts proliferating on the matrix surface, sparing its deeper part, even though the collagen matrix degradation seemed to occur following a gradient from the pADM surface inward. CONCLUSION: The unfavorable clinical results may be caused by the poor colonization of matrix cells and poor angiogenesis leading to the inadequate biointegration of pADM. Hence, the pADM structure in terms of porosity and degradability should be further investigated. CLINICAL SIGNIFICANCE: The present cases highlighted a poor integration of pADM following soft tissue grafting procedures, which was caused by the inadequate ultrastructure of the used pADM. Therefore, despite the utility of such tissue substitutes, their manufacturing improvement could be required to obtain a better biointegration.

Clinical, histological, and histomorphometrical analysis of maxillary sinus augmentation using inorganic bovine in humans: preliminary results.

The aim of the present study was to evaluate bone formation after maxillary sinus augmentation using bovine bone substitute material Bio-Oss alone by means of clinical, histological, and histomorphometrical examination of human biopsies. Deproteinized bovine bone (DPBB, Bio-Oss) was used to fill cavities after elevation of the sinus mucosa following major sinus pneumatization. Twenty patients with edentulous posterior maxillae were treated with 20 sinus augmentation procedures using a 2-stage technique. Residual lateral maxillary bone height was less than 3 mm. Forty-nine Straumann endosseous implants were used to complete the implant-prosthetic rehabilitation. Forty cylinder-shaped bone biopsies were taken from the augmented maxillary region 8 months after grafting during the second-stage surgery before implant placement. All implants were loaded 3 months after insertion, and no failures were recorded. Histomorphometrical analysis showed an average percentage of newly formed bone of 17.6% (± 2.8%) and a proportion of residual bone substitute material of 29.9% (± 4.9%) of the total biopsy area. Intimate contact between newly formed bone and Bio-Oss was detected along 28.2% (± 6.8%) of the particle surfaces. The results also showed that in all cases, the DPBB granules had been interconnected by bridges of vital newly formed bone. Inorganic bovine bone appears to be biocompatible and osteoconductive, and it can be used with success as a bone substitute in maxillary sinus augmentation procedures.

Human bone marrow-derived cells: an attractive source to populate dermal substitutes.

We have previously shown the importance of dermal fibroblasts within skin substitutes for promoting the emergence of a functional neodermis after grafting in humans. However, the use of fibroblasts from sources other than the dermis needs to be evaluated for patients with extensive skin loss. Here we examined the capacity of human bone marrow-derived cells (BMDCs), selected for their ability to adhere to plastic culture dishes, to behave like human dermal fibroblasts when incorporated within a 3D in vitro reconstructed tissue that promotes dermal fibroblast differentiation. Like dermal fibroblasts, BMDCs contracted a collagen matrix and were growth regulated by the matrix environment. They had the same shape and their nuclei had the same form factor as dermal fibroblasts. In addition, both cell types expressed desmin and vimentin but not alpha-smooth muscle actin. BMDCs deposited collagen types I and III, and fibrillin-1 with similar efficiency to dermal fibroblasts. In addition, BMDCs have the potential to regulate this deposition, as they produced metalloproteinases (MMP1, MMP2, and MMP9) and metalloproteinase inhibitors (TIMP1) very similarly to dermal fibroblasts. BMDCs can thus be induced to express functions resembling those of dermal fibroblasts, including those involved in the wound healing process.

Comparison of extracellular matrix in skin and saphenous veins from patients with varicose veins: does the skin reflect venous matrix changes?

Varicose vein disease is a frequently occurring pathology with multifactorial causes and a genetic component. An intense remodelling of the varicose vein wall has been described and could be at the origin of its weakness and altered elasticity. We have described previously a dysregulation of collagen synthesis in cultured smooth muscle cells from saphenous veins and in dermal fibroblasts from the skin of patients with varicose veins, suggesting a systemic defect in their connective tissue. The present study describes comparative morphological and immunohistochemical data in both the skin and saphenous veins of eight control subjects (undergoing coronary bypass surgery) and eight patients with varicose veins. Histological staining of glycoproteins, the elastic fibre network and collagen bundles showed that the remodelling and fragmentation of elastic fibres observed in varicose veins were also present in the skin of the patients. When compared with control subjects, we observed in both the veins and skin of patients with varicose veins (i) an increase in the elastic network, as quantified by image analysis; (ii) an accumulation of collagen type I, fibrillin-1 and laminin; and (iii) an overproduction of MMP (matrix metalloproteinase)-1, MMP-2 and MMP-3, analysed by immunohistochemistry, but normal levels of other MMPs (MMP-7 and MMP-9) and their inhibitors (TIMP-1, TIMP-2 and TIMP-3). An imbalance of extracellular matrix production/degradation was thus observed in veins as well as in the skin of the patients with varicose veins and, taken together, these findings show that remodelling is present in different organs, confirming systemic alterations of connective tissues.

Are cytokines linked to collagen breakdown during periodontal disease progression?

BACKGROUND: Evidence of the role of cytokines produced by resident and inflammatory cells during inflammation is well established. The aim of this study was to quantify in healthy and diseased human gingiva the area fraction (AA%) occupied by collagen fibers and the amount of cytokines such as interleukin (IL)-1beta, IL-4, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and epidermal growth factor (EGF) to investigate a possible correlation between such cytokines, collagen degradation, and the gingival index. METHODS: Gingival tissue specimens from 6 healthy controls (group 1), 6 patients with mild gingival inflammation (group 2), 6 patients with moderate gingival inflammation (group 3), and 6 patients with severe gingival inflammation (group 4) were cultured for 72 hours, and the cytokines present in the culture media were quantified using an enzyme-linked immunosorbent assay (ELISA). Paraffin gingival sections from the 24 subjects were stained with sirius red F3Ba for visualization of collagen fibers, then the area fraction (AA%) occupied by the gingival fibers was determined by automated image analysis. RESULTS: The present study revealed significant differences (P < 0.05) between means of AA% in group 1 (53%), group 2 (41%), group 3 (39.5%), and group 4 (35%) for collagen fibers. Compared to controls, there were significant increases of IL-1beta (groups 3 and 4), IL-6, and TNF-alpha (group 3); a significant decrease of IL-4 (groups 2, 3, and 4) and TGF-beta (groups-2 and, 3); and no change of EGF. The collagen AA% was significantly correlated with the amounts of IL-4 and TGF-beta, and significantly inversely correlated with the amounts of IL-1beta for all 3 inflamed groups and IL-6 and TNF-alpha for groups 2 and 3. CONCLUSION: The present study showed that EGF was not changed in inflamed gingival tissue and that IL-1beta and IL-4 were particularly and intensively correlated with collagen loss. These 2 cytokines could be markers of clinical severity during active periodontitis.