Collagen Fiber Exposure Research Articles

BMSC-HNC Interaction: Exploring Effects on Bone Integrity and Head and Neck Cancer Progression.

In recent research, the tumor microenvironment has been shown to attract mesenchymal stromal cells (MSCs), which is of particular interest due to its implications for cancer progression. The study focused on understanding the interaction between bone marrow-derived MSCs (BMSCs) and head and neck cancer (HNC) cells. This interaction was found to activate specific markers, notably the osteogenic marker alkaline phosphatase and the oncogene Runx2. These activations corresponded with the release of collagenase enzymes, MMP9 and MMP2. To gain insights into bone resorption related to this interaction, bovine bone slices were used, supporting the growth of "heterogeneous spheroids" that contained both BMSCs and HNC cells. Through scanning electron microscopy and energy-dispersive X-ray (EDX) analysis, it was observed that these mixed spheroids were linked to a notable increase in bone degradation and collagen fiber exposure, more so than spheroids of just BMSCs or HNC cells. Furthermore, the EDX results highlighted increased nitrogen content on bone surfaces with these mixed clusters. Overall, the findings underscore the significant role of BMSCs in tumor growth, emphasizing the need for further exploration in potential cancer treatment strategies.

Blood clot stabilization after different mechanical and chemical root treatments: a morphological evaluation using scanning electron microscopy.

PurposeThis in vitro study was conducted to evaluate the effects of different debridement techniques and conditioning procedures on root surface morphology and blood clot stabilization.MethodsTwo debridement techniques (curette [CU] vs. high-speed ultrasound [US]) and 2 conditioning procedures (ethylenediaminetetraacetic acid [EDTA] and phosphoric acid [PA]) were used for the study. Seven experimental groups were tested on root surfaces: 1) no treatment (C); 2) CU; 3) US; 4) CU+EDTA; 5) US+EDTA; 6) CU+PA; and 7) US+PA. Three specimens per group were observed under scanning electron microscopy (SEM) for surface characterization. Additional root slices received a blood drop, and clot formation was graded according to the blood element adhesion index by a single operator. Data were statistically analyzed, using a threshold of P<0.05 for statistical significance.ResultsThe C group displayed the most irregular surface among the tested groups with the complete absence of blood traces. The highest frequency of blood component adhesion was shown in the CU+EDTA group (P<0.05), while no differences were detected between the CU, US+EDTA, and CU+PA groups (P<0.05), which performed better than the US and US+PA groups (P<0.05).ConclusionsIn this SEM analysis, EDTA and conventional manual scaling were the most efficient procedures for enhancing smear layer removal, collagen fiber exposure, and clot stabilization on the root surface. This technique is imperative in periodontal healing and regenerative procedures.

EFFICACY OF NOVEL ROOT CANAL IRRTIGANT-MTAD AGAINST ROOT BIOMODIFIERS ON PERIODONTALLY INVOVLED TEETH IN PERIODONTAL REGENRATION- AN IN VITRO SCANNING ELECTRON MICROSCOPY STUDY.

Background: Smear layer removal and collagen fiber exposure may improve regeneration which can be accomplished by use of root biomodifiers. These enhance the degree of connective tissue attachment to denuded roots. The objective of this in vitro study was to evaluate and compare novel root canal irrigant and other root biomodifiers for smear layer removal on periodontally involved human teeth.&#x0D; Materials and Methods: Forty human teeth were collected and stored in saline. After scaling and root planing, two samples were obtained from each tooth. A total of 100 dentin blocks were randomly divided into four groups: Mixture of tetracycline, acid and detergent (MTAD), tetracycline hydrochloride (TTC HCl), citric acid (CA), and ethylenediaminetetraacetic acid (EDTA). The agents were applied for 3 min by active burnishing. Immediately following treatment, the specimens were rinsed, dehydrated, fixed and prepared for scanning electron microscope and were examined at × 3500 magnification. Sampaio’s index was evaluated by the previously trained blind examiner using photomicrographs. Groups were compared using analysis of variance followed by Tukey’s post?hoc test.&#x0D; Results: Mixture of tetracycline, acid, and detergent is most efficacious in removing the smear layer and showed statistically significant dentinal tubules opening, followed by EDTA, TTC HCl, and CA.&#x0D; Conclusion: Mixture of tetracycline, acid and detergent and conventional root biomodifiers used in the study alters the dentin surface by smear layer removal and exposure of dentinal tubules. Hence, MTAD as a root biomodifier may have a significant role in periodontal regeneration.&#x0D; Key words: Citric acid, ethylenediaminetetraacetic acid, MTAD, root biomodifier, scanning electron microscope study, tetracycline hydrochloride

Riboflavin-mediated photooxidation to improve the characteristics of decellularized human arterial small diameter vascular grafts

Vascular grafts with a diameter of less than 6 mm are made from a variety of materials and techniques to provide alternatives to autologous vascular grafts. Decellularized materials have been proposed as a possible approach to create extracellular matrix (ECM) vascular prostheses as they are naturally derived and inherently support various cell functions. However, these desirable graft characteristics may be limited by alterations of the ECM during the decellularization process leading to decreased biomechanical properties and hemocompatibility. In this study, arteries from the human placenta chorion were decellularized using two distinct detergents (Triton X-100 or SDS), which differently affect ECM ultrastructure. To overcome biomechanical strength loss and collagen fiber exposure after decellularization, riboflavin-mediated UV (RUV) crosslinking was used to uniformly crosslink the collagenous ECM of the grafts. Graft characteristics and biocompatibility with and without RUV crosslinking were studied in vitro and in vivo. RUV-crosslinked ECM grafts showed significantly improved mechanical strength and smoothening of the luminal graft surfaces. Cell seeding using human endothelial cells revealed no cytotoxic effects of the RUV treatment. Short-term aortic implants in rats showed cell migration and differentiation of host cells. Functional graft remodeling was evident in all grafts. Thus, RUV crosslinking is a preferable tool to improve graft characteristics of decellularized matrix conduits.

Effect of medicaments used in endodontic regeneration on the morphological characteristics of bovine radicular dentin: Experimental immature tooth model.

The purpose of this study was to evaluate the effect of different combinations of irrigating solutions and intracanal dressings in the pretreatment of bovine radicular dentin, using an experimental immature tooth model. Eighty healthy bovine teeth, simulated with incomplete rhizogenesis, were randomly distributed according to the protocols of root canal dentin pretreatment for a regenerative endodontic procedure (n = 10): Control (irrigation with distilled water); SH (irrigation with 1.5% Sodium Hypochlorite); EDTA (irrigation with 17% EDTA); SH/EDTA (irrigation with 1.5% SH + 17% EDTA); SH/CH/EDTA (irrigation with 1.5% SH + calcium hydroxide paste +17% EDTA); SH/MTAP/EDTA (irrigation with 1.5% SH + modified triple antibiotic paste + EDTA 17%); SH/TAP/EDTA (irrigation with 1.5% SH + triple antibiotic paste +17% EDTA) and SH/DAP/EDTA (irrigation with 1.5% SH + double antibiotic paste + EDTA 17%). After the completion of the protocol, the demineralization, the exposure of collagen fibers, and the dentin erosion was evaluated under scanning electron microscopy (SEM), by applying a score system (1-3) to classify the observed features. Statistical analysis was performed (Kruskal-Wallis and Dunn Multiple Comparison tests-p < .05). SH/TAP/EDTA and SH/DAP/EDTA groups presented the highest rates of demineralization in both the coronal and middle thirds of the root (p < .05). In the SH/MTAP/EDTA group, the samples presented moderate demineralization. The samples from the SH/CH/EDTA group presented similar findings to the control group (p < .05). Conventional triple antibiotic (TAP) and double antibiotic (DAP) pastes promoted more pronounced morphological changes on the dentin surface.

EDTA Treatment for Sodium Hypochlorite–treated Dentin Recovers Disturbed Attachment and Induces Differentiation of Mouse Dental Papilla Cells

IntroductionThe disturbance of cellular attachment to dentin by sodium hypochlorite (NaOCl) may hamper pulp tissue regeneration. The aims of this study were to examine the recovering effect of EDTA on the attachment/differentiation of stemlike cells and to address the mechanisms of EDTA-induced recovery under the hypothesis that attachment to the exposed dentin matrix and the subsequent activation of integrin/phosphatidylinositol 3-kinase (PI3K) signaling play a crucial role. MethodsMouse dental papilla (MDP) cells were cultured on bovine dentin disks treated with NaOCl (0%, 1.5%, or 6%) followed by EDTA (0%, 3%, or 17%). Cell attachment was evaluated by cell density, viability, and scanning and transmission electron microscopy. Odonto-/osteoblastic gene expression in attached MDP cells was analyzed with or without a pan-PI3K inhibitor (LY294002) using real-time polymerase chain reaction. ResultsNaOCl treatment (1.5%, 10 minutes) significantly diminished attached MDP cells (P < .00001), but EDTA treatment (3% and 17%, ≥10 minutes) of NaOCl-pretreated dentin induced a significant increase in attached cells (P < .05). Ultrastructurally, MDP cells on EDTA-treated dentin showed attachment to exposed collagen fibers. MDP cells cultured on EDTA-treated disks (with or without 1.5% NaOCl pretreatment) showed significant up-regulation of alkaline phosphatase, dentin matrix protein 1, and dentin sialophosphoprotein messenger RNAs (P < .05). Alkaline phosphatase expression was down-regulated by LY294002 (P < .05). ConclusionsUnder the present experimental conditions, 10 minutes of EDTA treatment was sufficient to recover attachment/differentiation of MDP cells on 1.5% NaOCl-pretreated dentin. EDTA-induced exposure of collagen fibers and subsequent activation of integrin/PI3K signaling may contribute, at least partly, to the recovery.

Comparative in vitro SEM study of a novel root canal irrigant-MTAD and conventional root biomodifiers on periodontally involved human teeth.

Background:Smear layer removal and collagen fiber exposure may improve regeneration which can be accomplished by use of root biomodifiers. These enhance the degree of connective tissue attachment to denuded roots. The objective of this in vitro study was to evaluate and compare novel root canal irrigant and other root biomodifiers for smear layer removal on periodontally involved human teeth.Materials and Methods:Forty human teeth were collected and stored in saline. After scaling and root planing, two samples were obtained from each tooth. Thus, a total of 80 dentin blocks were randomly divided into four groups: Mixture of tetracycline, acid and detergent (MTAD), tetracycline hydrochloride (TTC HCl), citric acid (CA), and ethylenediaminetetraacetic acid (EDTA). The agents were applied for 3 min by active burnishing. Immediately following treatment, the specimens were rinsed, dehydrated, fixed and prepared for scanning electron microscope and were examined at × 3500 magnification. Sampaio's index was evaluated by the previously trained blind examiner using photomicrographs. Groups were compared using analysis of variance followed by Tukey's post-hoc test.Results:Mixture of tetracycline, acid, and detergent is most efficacious in removing the smear layer and showed statistically significant dentinal tubules opening, followed by EDTA, TTC HCl, and CA.Conclusion:Mixture of tetracycline, acid and detergent and conventional root biomodifiers used in the study alters the dentin surface by smear layer removal and exposure of dentinal tubules. Hence, MTAD as a root biomodifier may have a significant role in periodontal regeneration.

An in vitro scanning electron microscopic study comparing MTAD (intracanal irrigant) and various root biomodifiers on periodontally involved human teeth

Background: Smear layer removal and collagen fiber exposure may improve regeneration outcome, which can be accomplished by use of root biomodifiers. These enhance the degree of connective tissue attachment to denuded roots. The objective of this in vitro scanning electron microscopic study was to comparatively evaluate mixture of tetracycline (TTC) and acid and detergent (MTAD) and other root biomodifiers for smear layer removal on periodontally involved human teeth. Materials and Methods: Forty human teeth were collected and stored in saline. After scaling and root planning, two samples were obtained from each tooth. A total of 80 dentin blocks were randomly divided into four groups: MTAD, TTC hydrochloride (TTC HCl), citric acid (CA), and normal saline. The agents were applied for 3 min by active burnishing. Immediately following treatment, the specimens were rinsed, dehydrated, fixed and prepared for scanning electron microscope and was examined at Χ3500 magnification. Previously trained blind examiners evaluated photomicrographs using Sampaio's index (2005). Statistical analysis was performed. Results: MTAD is most efficacious in removing smear layer and showed statistically significant dentinal tubules opening, followed by TTC HCl and CA. Conclusion: MTAD and conventional root biomodifiers used in the study alters the dentin surface by smear layer removal and exposure of dentinal tubules. Hence, MTAD as a root biomodifier may have a significant role in periodontal regeneration .

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

ObjectiveThe aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. Material and MethodsA total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. ResultsBrushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. ConclusionDespite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning.

Blood Cells Attachment after Root Conditioning and PRP Application: An in vitro Study

Root conditioning is aimed at smear layer removal and at dental matrix collagen exposure, which may promote periodontal regeneration. This in vitro study assessed smear layer removal, collagen fiber exposure and the influence of PRP (platelet-rich plasma) application on adhesion of blood cells to the root surface using scanning electron microscopy (SEM). Scaled root samples (n = 160) were set in five groups and conditioned with: group I - control group (saline solution); group II (EDTA 24%); group III (citric acid 25%); group IV (tetracycline hydrochloride 50 mg/ml); group V (sodium citrate 30%). Eighty samples were assessed using the root surface modification index (RSMI). The other eighty samples were set in two groups. The first group (n = 40) received PRP gel application with a soft brush and the second group (n = 40) received PRP application and then a blood drop. The fibrin clot formation was assessed in the first group and the blood cells adhesion was assessed in the second group using the BEAI (blood elements adhesion index). A previously trained, calibrated, and blind examiner evaluated photomicrographs. Statistical analysis was performed using the Kruskal-Wallis's and Dunn's tests. Group III attained the best results for RSMI and BEAI. Moreover, it was the only group showing fibrin clot formation. Citric acid was the most efficient conditioner for smear layer removal, collagen fiber exposure and blood cell adhesion. Moreover, it was the only group showing fibrin clot formation after PRP application. This study demonstrated that root conditioning followed by PRP application may favor blood cell adhesion on root surface which may optimize periodontal healing.

Smear Layer Removal for Collagen Fiber Exposure after Citric Acid Conditionings

The aim of the present study was to compare the removal of the smear layer and exposure of collagen fibers of the root surface following the application of five citric acid solution concentrations. Two hundred seventy (270) samples were equally divided into six groups (n=45) for treatment with saline solution (control) and five different concentrations of citric acid (0.5, 1, 2, 15, and 25 percent). Three acid application methods were used (passive, brushing, and burnishing) as well as three application periods (1, 2, and 3 minutes). A previously trained, calibrated (kappa score = 0.93), and blind examiner subsequently scored scanning electron micrographs (SEMs) of the samples. Statistical analyses were performed by using Kruskal-Wallis and Dunn's post-hoc tests. According to the results obtained and within the limitations of the methodology used, the citric acid applications were more effective than the control treatment of applying saline solution (p<0.05). However, no statistically significant differences were observed among the three application methods and three application periods. Descriptive analyses showed that best results for exposure of collagen fibers were obtained with the application of citric acid at 25 percent by brushing for 1 or 3 minutes. The best results for exposure of collagen fibers in this study were obtained with application of citric acid at 25 percent by brushing for 1 or 3 minutes, even though there were no statistically significant differences among the groups. The best results for exposure of collagen fibers on root surfaces noted in this study were obtained with application of citric acid at 25 percent by brushing for 1 or 3 minutes.

The effect of chemical and/or mechanical conditioning on the Er:YAG laser‐treated root cementum: Analysis of surface morphology and periodontal ligament fibroblast attachment

This study compared the surface morphology as well as the biocompatibility of dental root cementum treated with Er:YAG laser irradiation alone and with the laser irradiation followed by chemical and/or mechanical conditioning. Healthy cementum plates were randomly assigned to the following control and treatment groups: (1) untreated control (C), (2) Er:YAG laser irradiation (L), (3) laser plus tetracycline HCl (TC) placement (L+TP), (4) laser plus TC burnishing (L+TB), (5) laser plus EDTA gel placement (L+EP), (6) laser plus EDTA gel burnishing (L+EB), (7) laser plus saline solution burnishing (L+SB), and (8) laser plus minocycline-HCl paste placement (L+MP). Specimens were subjected to scanning electron microscopy (SEM), histological observation and attachment assay using periodontal ligament (PDL) fibroblasts. The laser irradiation produced a thin affected layer (5.7 microm thickness) with a superficial microstructure on the cementum surface. The characteristic microstructures of the lased surface were fragile and could be removed by chemical and/or mechanical conditioning treatments. The L+TB group exhibited marked exposure of collagen fibers after removal of the microstructures on the lased surface. The L+EP group presented a peculiar, smooth surface without exposure of collagen fibers and a uniform arrangement of spherical microparticles on the ultra-high magnification of SEM. In cell attachment assay, the L+TB group exhibited the greatest number of attached cells among all the groups, followed by the L+EP, L+SB and control group. The laser alone group exhibited the lowest number of cells. The characteristic microstructure of the root cementum surface after Er:YAG laser irradiation has a tendency to hinder the early attachment of PDL cells. However, chemical and/or mechanical root conditioning treatment may improve and increase the biocompatibility of the Er:YAG laser-treated root cementum by removing the microstructures of the surface and/or further exposing the collagen fibers.

Smear Layer Removal and Collagen Fiber Exposure Using Tetracycline Hydrochloride Conditioning

Smear layer removal and collagen fiber exposure may improve periodontal treatment and regeneration. This in vitro study assessed smear layer removal and collagen fiber exposure after tetracycline hydrochloride (TTC) application on root surfaces using scanning electron microscopy (SEM). Root cementum was removed with diamond burs followed by scaling and root planning. Four hundred fifty samples were divided into ten groups: a control (saline application) and nine different TTC concentrations were applied at doses of 10, 25, 50, 75, 100, 125, 150, 200, and 250 mg/ml. The TTC application was performed in all groups in three different ways (passive, brushing, and burnishing) and at three different periods of conditioning (1, 2, and 3 minutes). A previously trained, calibrated, and blind examiner evaluated photomicrographs of the samples using Sampaio's index (2005). Statistical analysis was performed using the Kruskal-Wallis' and Dunn's tests. The concentrations of 50 mg/mL and 75 mg/mL applied by burnishing were the most effective in smear layer removal and collagen fiber exposure. Both the passive mode of application (p=0.0001) and 1 minute period of application (p=0.002) were the least effective. The concentrations of 50 mg/mL and 75 mg/mL applied by burnishing during 2 or 3 minutes were the most effective. These parameters may be applied in periodontal procedures involving TTC root conditioning to optimize results.

Cloning and Analysis of the Thrombopoietin-induced Megakaryocyte-specific Glycoprotein VI Promoter and Its Regulation by GATA-1, Fli-1, and Sp1

The exposure of collagen fibers at sites of vascular injury results in the adherence of platelets and their subsequent activation. The platelet collagen receptor glycoprotein (GP)(1) VI plays a crucial role in platelet activation and thrombus formation and decreased levels or defective GPVI may lead to excessive bleeding. In addition, elevated levels of collagen receptors may predispose individuals to coronary heart disease or strokes. GPVI expression is restricted to platelets and their precursor cell, the megakaryocyte. In this study we investigate the regulation of GPVI expression and show that thrombopoietin induces its expression in the megakaryocytic cell line UT-7/TPO. A 5'-region flanking the transcription start point of the GPVI gene was cloned (-694 to +29) and we report that this putative GPVI promoter bestows megakaryocye-specific expression. Deletion analyses and site-directed mutagenesis identified Sp1(227), GATA(177), and Ets(48) sites as essential for GPVI expression. We show that transcription factors GATA-1, Fli-1, and Sp1 can bind to and activate this promoter. Finally, GPVI mRNA was detected only in megakaryocytic cell lines expressing both Fli-1 and GATA-1, and we show that overexpression of Fli-1 in a stable cell line (which expresses endogenous GATA-1 and Sp1) results in expression of the endogenous GPVI gene.

Scanning electron microscopic evaluation of the arthritis in MRL/lpr mice.

The articular surfaces of disarticulated knee joints from MRL/lpr and MRL/n mice, aged 4-33 weeks were examined by light microscopy (LM) and scanning electron microscopy (SEM). Light microscopy did not reliably predict SEM findings. Most of the abnormalities detected by SEM were related to surface disruption of articular cartilage. However, areas of articular cartilage covered by tightly adherent non-confluent monolayers of stellate-shaped cells with intertwining cytoplasmic processes were observed. In these areas the integrity of the underlying cartilage matrix was disrupted, with exposure of collagen fibers. These findings suggested that outgrowth of proliferating synovial cells in the joints of arthritic MRL/lpr mice may lead to cartilage destruction.

Attachment of cementum on different hydroxylapatite ceramic (HAC) substrata in vivo. A light and electron microscopic study.

The role of substrate surface characteristics for periodontal regeneration was studied in rats. Cementogenesis was initiated by dental follicle cells retained after dissecting out a molar tooth germ in 5-day-old rats. The tooth germ was substituted by a bone replacement material, namely HAC granules of porous consistency. Tissue blocks were removed after 24 weeks and processed for light and electron microscopic examination. On all HAC surfaces a new cementum-like tissue developed, similar to that of natural root surfaces. The results strongly indicate that the exposure of collagen fibers is not essential in order to achieve new periodontal attachment.

The Influence of Chemically-induced Modifications of Root Surfaces on Cell Migration, Attachment, and Orientation

Surface demineralization of tooth root surfaces has been shown to improve re-attachment of cells and to promote tissue reconstruction following periodontal surgery. Exposure of collagen fibers has been thought to facilitate migration, attachment, and orientation of fibroblasts on the root surface. However, using an in vitro assay, we have found that both attachment and orientation of human gingival fibroblasts on demineralized dentin surfaces are further improved following digestion of the exposed collagen with bacterial collagenase. In contrast, pronase and trypsin digestion of the surface collagen had no significant effect, whereas heat denaturation had an inhibitory effect. Dissociative extraction of the demineralized dentin slices with 4 mol/L guanidine hydrochloride (GuHCl) also improved attachment and orientation, and when undemineralized dentin was subjected to dissociative extraction, cell attachment was comparable and orientation superior to that on demineralized surfaces. These studies indicate that demineralization is not a prerequisite for facilitating attachment, and that enhanced attachment and orientation of cells are not dependent upon a collagenous substratum.