Laminin-5 gamma2-chain and collagenase-2 (MMP-8) in human peri-implant sulcular fluid

Laminin-5 (LN-5) is an important epithelial cell-derived structural and adhesive component in hemidesmosomes and basement membranes (BM). In peri-implant tissue, gingival BM underlies the junctional epithelium (JE) and reflects the peri-implant health. Matrix metalloproteinase-8 (MMP-8 or collagenase-2) is one of the key mediators of periodontal tissue destruction. Western immunoblotting with image analysis was used to quantitate the molecular forms of LN-5 gamma2-chain and MMP-8 in peri-implant sulcular fluid (PISF) from healthy and diseased implants. These observations were related to the recorded gingival (GI) and bone resorption (BR) indices of the studied sites. Altogether, 72 PISF samples from osseointegrated dental implants were examined. Significantly elevated levels of fragmented LN-5 gamma2-chain species (45 and 70 kDa) and MMP-8 immunoreactivities were observed in diseased PISF in relation to healthy PISF. The elevated levels of both LN-5 gamma2-chain 45 and 70 kDa fragments and MMP-8 in diseased PISF from peri-mucositis (BR = 0) and peri-implantitis (BR >/= 1) lesions strongly correlated with elevated GI. Low levels - almost comparable to those seen in healthy control PISF - were seen in PISF from peri-implantitis lesions (BR >/= 1) with no GI. Activation of 75 kDa neutrophil (PMN)-type proMMP-8 to 10 kDa lower-molecular-size active forms was especially detected in PISF from peri-implantitis with elevated GI. These cross-sectional findings indicate that elevated MMP-8 and LN-5 gamma2-chain fragment levels in PISF can reflect the active phase of the inflammatory peri-implant disease. Longitudinal studies are required to assess their use, either alone or in combination as molecular biochemical PISF markers, to predict the risk of progression of peri-implantitis, as well as to monitor the impact of treatment of the disease.     

Effect of platelet-rich plasma on the healing of intrabony defects treated with an enamel matrix protein derivative and a natural bone mineral

Background: Regenerative periodontal surgery utilizing a combination of an enamel matrix protein derivative (EMD) and a natural bone mineral (NBM) and platelet‐rich plasma (PRP) has been shown to enhance the outcomes of regenerative surgery significantly. At present, it is unknown whether root conditioning with EMD, followed by defect fill with a combination of NBM+PRP may additionally enhance the clinical results obtained with EMD+NBM. Aim: To compare clinically the treatment of deep intrabony defects with either EMD+NBM+PRP or EMD+NBM. Material and Methods: Twenty‐six patients suffering from advanced chronic periodontitis, and each of whom displayed one advanced intrabony defect were randomly treated with either EMD+NBM+PRP (test) or EMD+NBM (control). The following clinical parameters were evaluated at baseline and at 1 year after treatment: plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR) and clinical attachment level (CAL). The primary outcome variable was CAL. Results: Healing was uneventful in all patients. At 1 year after therapy, the test sites showed a reduction in mean PD from 8.8±1.9 mm to 3.1±0.9 mm ( p<0.001) and a change in mean CAL from 10.8±2.0 mm to 6.0±1.5 mm ( p<0.001). In the control group the mean PD was reduced from 8.8±2.0 mm to 2.8±1.6 mm ( p<0.001) and the mean CAL changed from 10.5±1.6 mm to 5.5±1.4 mm ( p<0.001). CAL gains of 4 mm were measured in 77% (i.e. in 10 out of 13 defects) of the cases treated with EMD+NBM+PRP and in 100% (i.e. in all 13 defects) treated with EMD+NBM. No statistically significant differences in any of the investigated parameters were observed between the two groups. Conclusions: Within its limits, the present study has shown that (i) 1 year after regenerative surgery, both treatments resulted in statistically significant PD reductions and CAL gains and (ii) the use of PRP failed to enhance the results obtained with EMD+NBM.     

Effect of dental materials calcium hydroxide-containing cement, mineral trioxide aggregate, and enamel matrix derivative on proliferation and differentiation of human tooth germ stem cells

Introduction

Biocompatibility of pulp capping materials is important for successful use in dentistry. These materials should be nontoxic and permissive for proliferation and induction of odontogenic differentiation of pulp cells. The aim of our study was to evaluate the effects of enamel matrix derivative (EMD), mineral trioxide aggregate (MTA), and calcium hydroxide-containing cement (DYCAL) on proliferation and odontogenic differentiation of human tooth germ stem cells (hTGSCs) in which cells belonging to both pulp tissue and dental follicle exist.

Methods

The 96-well plates, 24-well plates, and special chamber slides were coated with biomaterials for cell proliferation, differentiation, and scanning electron microscopy analysis. Odontogenic differentiation of hTGSCs was evaluated by analyzing mRNA expression of dentin sialophosphoprotein (DSPP) by real-time polymerase chain reaction expression analysis, measurement of alkaline phosphatase activity, and visualization of calcium depositions by von Kossa staining.

Results

Our results demonstrate that EMD is the best material in terms of inducing differentiation and proliferation of hTGSCs. DYCAL was found to be toxic to hTGSCs; however, EMD-coated DYCAL showed less toxicity. EMD-coated MTA was not efficient at inducing proliferation and differentiation.

Conclusions

Pulp capping materials come in direct contact with dental pulp cells; thus, they require comprehensive evaluation of interactions between cells and biomaterials. Therefore, we cultured hTGSCs, capable of odontogenic differentiation, on pulp capping materials directly. Our results suggest that combination of capping materials with EMD would increase the quality of capping by increasing biocompatibility of capping materials.     

Proanthocyanidin encapsulation for sustained bioactivity in dentin bioadhesion: A two-year study

ObjectivesTo determine the long-term effect on the stability of dentin-resin interfaces after the addition of polylactide (PLA) capsules containing proanthocyanidin (PAC) to adhesive resin.MethodsSub-micron (SM) and micron (M) size capsules containing PACs were produced using a combination of emulsification and solvent evaporation techniques and characterized. Human dentin surfaces (n = 8) were etched (35% glycolic acid) and primed (15% enriched Vitis vinifera extract solution - VV_e), followed by the application of an experimental adhesive containing 0 (control), 1.5 wt% of SM or M PAC-filled PLA capsules light cured for 40 s. A crown was built using commercial composite. After 24 h-immersion (37 °C) in simulated body fluid, specimens were serially sectioned into resin-dentin beams. Microtensile bond strength (TBS), micro-permeability and fracture pattern were assessed immediately and after 1 and 2 years. Data were statistically analyzed using two-way ANOVA and post-hoc test (α = 0.05).ResultsPolydisperse capsules were manufactured with average diameter of 0.36 µm and 1.08 µm for SM and M, respectively. The addition of capsules did not affect TBS (p = 0.889). After 2 years, TBS significantly decreased in SM (p = 0.006), whereas M showed similar initial values (p = 0.291). Overall, less micro-permeability was found in M than the control and SM group (p < 0.001). After 2 years, fractured surfaces from capsule-containing groups failed within the adhesive layer while control fractured at the bottom of the hybrid layer.SignificanceThe addition of PAC-filled PLA microcapsules in a dental adhesive did not affect the bond strength while increased and sustained the protection against micro-permeability in the interface, likely due to release of PACs.     

Healing of experimental gingival recession defects treated with amnion allograft: Histologic and histometric analysis in dogs

ObjectivesThis study was conducted to compare the healing response of localized gingival recession defects treated with a coronally advanced flap (CAF) and either an amnion allograft membrane (AM) or a connective tissue graft (CTG).MethodsGingival recession defects were surgically created in six healthy mongrel dogs at the labial root surface of the maxillary canines, bilaterally. Using a split mouth design, the defects were treated with CAF and either AM (CAF/AM) or CTG (CAF/CTG). Three animals for each group were scarified at 1 and 3 months. Segments containing the defects were prepared for histological and histometric analysis.ResultsBoth techniques showed similar clinical findings with adequate root coverage. Histologically, healing was characterized by the formation of new cementum and new connective tissue attachment in the CAF/AM group; in the CAF/CTG group, healing was characterized by junctional epithelium, coronally, and connective tissue fibers parallel to the root surface, apically. Histometrically, the CAF/AM group revealed a substantially shorter epithelial length and a longer, new cementum compared with those of the CAF/CTG group after a healing period of 3 months.ConclusionsWithin the limits of this study, we concluded that the AM allograft could promote periodontal healing in gingival recession defects.     

Adipokines in dental pulp: Physiological,pathological, and potential therapeutic roles

BackgroundHundreds of adipokines have been identified, and their extensive range of endocrine functions—regulating distant organs such as oral tissues—and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.HighlightsThe most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.ConclusionAdipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.     

Calvarial bone regeneration by a combination of natural anorganic bovine-derived hydroxyapatite matrix coupled with a synthetic cell-binding peptide (PepGen): an experimental study in rats

Objectives: The aim of this study was to evaluate histologically the effect of natural anorganic bovine‐derived hydroxyapatite matrix (ABM) coupled with a synthetic cell‐binding peptide on the healing of critical size calvarial defects in rats. Material and methods: Sixteen 4‐month‐old rats were used in the study. A 5 mm trephine defect was created in each parietal bone of every animal. One defect was left untreated (control) while the contralateral defect was treated with a natural ABM coupled with a synthetic cell‐binding peptide (test). At 60 and 120 days post‐operatively, groups of eight animals were sacrificed and 7–10‐μm‐thick decalcified sections were produced from both test and control sides. Three sections, 100 μm apart, representing the central area of each defect were selected for the histometric analysis. Results: Histological analysis showed limited bone formation in both control and test defects at both observation periods. The control defects healed with fibrous connective tissue occupying the midportion of the defect and minimal new bone formation at the periphery. In the test defects, the major part of the defect was occupied by graft particles embedded in connective tissue. After 60 days of healing the residual defects accounted up to 94.6% of the original defect dimensions in the control specimens and 90.6% in the test specimens. The differences between test and control defects were not statistically significant (P=0.06). After 120 days of healing, the residual defects accounted up 89.9% of the original defect dimensions in the control specimens and 85% in the test specimens. The difference was not statistically significant (P=0.33). Conclusion: The ABM coupled with a synthetic cell‐binding peptide failed to substantially promote new bone formation in rat calvarial defects.     

Cloning of hamster osteopontin and expression distribution in normal tissues and experimentally induced oral squamous-cell carcinoma

Osteopontin (OPN) is a non-collagenous extracellular matrix (ECM) protein expressed and secreted by several human cancers. This study investigated the expression pattern of OPN during development of oral squamous-cell carcinoma by using 7,12-dimethylbenz[a]anthracene (DMBA)-induced squamous-cell carcinomas in buccal pouch of syrian golden hamsters. We first identified the hamster OPN cDNA sequence by screening of a hamster calvariae cDNA library with a rat OPN cDNA probe. The resulting 1,449 bp of hamster OPN cDNA led to a deduced protein sequence of 305 amino acids containing several putative binding sites to integrins, CD44 receptors, calcium ions and hydroxyapatite, as well as multiple sites for phosphorylation, glycosylation and sulphation. Hamster OPN cDNA was then used as a probe to analyze the expression of OPN mRNA by Northern blot and in situ hybridization analyses of normal and malignant tissues. OPN mRNA was detected in several non-mineralized tissues as well as in mineralized tissues, but was not present in normal hamster buccal epithelium. DMBA-treated hamster buccal pouches expressed OPN mRNA as early as 4 weeks and displayed the highest level of expression at 15 weeks. The specimens treated with DMBA for 15 weeks exhibited histological features of squamous-cell carcinoma, presented microcrystalline deposits and showed OPN expression associated with malignant epithelium and tumor-associated macrophages. To summarize, our results suggest that buccal-pouch carcinogenesis of Syrian golden hamster may constitute an excellent experimental model to study the mechanisms by which OPN is associated with oral cancer pathogenesis, and to validate OPN-based therapeutic approaches to ameliorate oral cancer progression and metastasis.