Krüppel-like factor 6 promotes odontoblastic differentiation through regulating the expression of dentine sialophosphoprotein and dentine matrix protein 1 genes.

AIM: To investigate the potential role of Krüppel-like factor 6 (KLF6) in the odontoblastic differentiation of immortalized dental papilla mesenchymal cells (iMDP-3) cells. METHODOLOGY: Alizarin Red S (ARS) and Alkaline phosphatase (ALP) staining was used to examine the mineralization effect of iMDP-3 cells after odontoblastic induction. Real-time PCR and Western blotting were employed to analyse dentine sialophosphoprotein (DSPP), dentine matrix protein 1 (DMP1), RUNX family transcription factor 2 (RUNX2), ALP and KLF6 expression during this process. Co-expression of the KLF6 with DMP1, DSPP and RUNX2 was detected by double immunofluorescence staining to explore their local relationship in the cell. To further investigate KLF6 functions, Klf6 gain- and loss-of-function assays followed by ARS and ALP stainings, real-time PCR and Western blotting were performed using Klf6-overexpression plasmids and Klf6 siRNA to investigate whether changes in Klf6 expression affect the odontoblastic differentiation of iMDP-3 cells. Dual-luciferase reporter assays were used to elucidate the mechanistic regulation of Dspp and Dmp1 expression by Klf6. Means were compared using the unpaired t-test and Kruskal-Wallis one-way anova with P < 0.05 and P < 0.01 defined as statistical significance levels. RESULTS: The expression levels of Klf6 (P < 0.01), Dspp (P < 0.05), Dmp1 (P < 0.01), Runx2 (P < 0.01) and Alp (P < 0.01) were significantly elevated during odontoblastic differentiation of iMDP-3 cells. KLF6 was co-localized with DSPP, DMP1 and RUNX2 in the cytoplasm and nucleus of iMDP-3 cells. Overexpression of Klf6 promoted the odontoblastic differentiation of iMDP-3, whereas the inhibition of Klf6 prevented this procession. Dual-luciferase assays revealed that Klf6 upregulates Dspp and Dmp1 transcription in iMDP-3 cells during odontoblastic differentiation. CONCLUSION: Klf6 promoted odontoblastic differentiation by targeting the transcription promoter of Dmp1 and Dspp. This study may offer novel insights into strategies for treating injuries to dental pulp tissue.

Morphometrics and molecular analysis of the free-living nematode, Belondira bagongshanensis n. sp. (Dorylaimida, Belondiridae), from China.

A new species, Belondira bagongshanensis n. sp., extracted from soil under grass in Bagongshan Forest Park, Anhui Province, China, is described and illustrated. The new species is mainly characterized by a body length 1.6-2.1 mm; cephalic framework moderately sclerotized; odontostyle robust with a distinct lumen; anterior part of pharynx with a distinct fusiform swelling, bearing distinct sclerotized valve plates and basal expansion occupying about three-fifths of the total neck length; female genital system mono-opisthodelphic and anterior branch 0.8-1.6 times the corresponding body diameter; tail short and hemispheroid; male spicules 36-49 µm long and two widely spaced ventromedian supplements. The new species is close to B. wajahati, B. golden and B. eugeniae in possessing a short tail, a robust odontostyle with a distinct aperture and a moderately sclerotized cephalic framework. New sequences of 18S rDNA and the D2-D3 region of 28S rDNA of the new species were also identified.

Morphology of Labronemella major n. sp. (Nematoda: Dorylaimida), a soil-dwelling nematode from China, including a revised key to species of the genus.

One new species from Qinghai Province, China, Labronemella major n. sp., is described. The new species is characterized by a body length of 3.03-3.34 mm; lip region wide, offset by a distinct depression, disc-like with six separated inner liplets; amphid fovea funnel-shaped, distinctly bulged on body surface in scanning electron micrographs; odontostyle long (35-39 µm) with distinct lumen, aperture about 39-47% of its length; odontophore rod-like and long; guiding ring double; pharyngeal basal expansion about half of the total neck length; uterus relatively long and tripartite; vulva transverse and sclerotized; spicules 81-90 µm long; ventromedial supplements 19-23; tail short, rounded to conoid. It can be differentiated from all other species of the genus by its relatively longer body, odontostyle and spicules, and wider lip region. Due to the lip region being offset by a deep constriction, and the long (three or more times the body diameter at mid-body) tripartite uterus, the new species is close to Labronemella czernowitzensis (Micoletzky, 1922) Andrássy, 2002 and Labronemella labiata Andrássy, 1985. An improved key to the genus including the new species is provided.

Morphology and morphometrics of Heterodorus qinghaiensis n. sp. (Dorylaimida, Nordiidae) from soil samples in China.

One new species of the family Nordiidae Jairajpuri & Siddiqi, 1964 from the enclosure grassland of Qinghai Province, China, Heterodorus qinghaiensis n. sp., is described and illustrated. The new species is characterized by the slender body, 1.29-1.46 mm in length; the granular lateral chord with numerous large depression plaques throughout its entirety; the lip region offset by a distinct depression; amphid goblet-shaped with aperture about half to two-thirds of corresponding body diameter; odontostyle 11-13 µm long; rod-like odontophore without basal flanges; pharyngeal basal expansion about one-third of the total neck length; didelphic genital system containing sperm; ovaries generally not reaching the sphincter level; vulva transversed and sclerotized; female tail conoid with round terminus; 3-5 spaced ventromedial supplements and spicule 32-41 µm long. It is close to H. liangi (Ahmad, Wu & Shaheen, 2002) Andrássy, 2009, H. brevidentatus (Thorne, 1939) Andrássy, 2009, H. monticola Andrássy, 2011, H. morgensis (Loof, 1988) Andrássy, 2009 and H. meghalayensis (Mushtaq, Baniyamuddin & Ahmad, 2007) Andrássy, 2009 in having inconspicuous or no lateral body pores, smaller odontostyle and ventrally curved tail.

[A biomechanical evaluation of odontoid screw plate fixation system].

OBJECTIVE: To evaluate the biomechanical stability of anterior odontoid screw plate (AOSP). METHODS: Eight fresh-frozen cadaveric cervical spine specimens were subjected to stepwise destabilization of the C1-C3 complex, simulating a type Ⅰ Hangman fracture, type Ⅱ odontoid fracture, and the C2-3 disc injury. Intact specimens, fractured specimens, and fractured specimens with posterior, anterior fixation techniques were divided into six groups: control group (intact), injury group of type Ⅱ odontoid fracture and type Ⅰ Hangman fracture combined with C2-3 disk injury, after anterior cervical plate+ odontoid screw+ cage (ACP+ OS+ cage) group, after anterior odontoid screw plate (AOSP) fixation system group, after affixing rods from pedicle screws in C2 to lateral mass screws in C3+ odontoid screw (C2PS+ C3LMS+ OS) group, after affixing rods from pedicle screws in C1 to pedicle screws in C2 and lateral mass screws in C3 (C1PS+ C2PS+ C3LMS) group. The range of motion (ROM) and neutral zone of C1-C2 and C2-C3 segment was tested. RESULTS: There was statistically significant difference between the C1PS+ C2PS+ C3LMS fixation group and the AOSP fixation group of ROMC1-C2(P<0.05). During all loading modes, AOSP+ Bone graft fixation significantly outperformed the ACP+ OS+ cage fixation in limiting ROMC2-C3. During flexion and extension, AOSP fixation significantly outperformed the C1PS+ C2PS+ C3LMS fixation and C2PS+ C3LMS+ OS fixation in limiting ROMC2-C3. CONCLUSION: The AOSP fixation system has excellent biomechanical performance when dealing with type Ⅰ Hangman fracture, type Ⅱ odontoid fracture, and the C2-3 disc injury, and appear to be a safe and effective technique for dealing with the combined injury.

Guided bone regeneration using acellular bovine pericardium in a rabbit mandibular model: in-vitro and in-vivo studies.

BACKGROUND AND OBJECTIVE: To investigate the feasibility of acellular bovine pericardium (BP) for guided bone regeneration (GBR) in vitro and in vivo. The success of GBR relies on the fact that various cellular components possess different migration rates into the defect site and that a barrier membrane plays a significant role in these processes. MATERIAL AND METHODS: BP membrane was isolated and decellularized using an enzymatic method. The microarchitecture, mechanical properties, cytotoxicity and cell chemotaxis properties of the acellular BP were evaluated in vitro, and the in-vivo efficacy of the acellular BP was also investigated in a rabbit mandibular model. RESULTS: The acellular BP membrane possessed an interconnected fibrous structure. Glutaraldehyde (GA) treatment was efficient for enhancement of the mechanical properties of the acellular BP bur and resulted in negligible cytotoxicity. After 16 wk, standardized osseous defects created in the rabbit mandible, and covered with acellular BP, were associated with an enhanced deposition of mineralized tissue when compared with defects left to spontaneous healing. CONCLUSION: GA-treated acellular BP is promising as a barrier membrane for GBR for further in-vivo and clinical studies.

Streptococcus cristatus ArcA interferes with Porphyromonas gingivalis pathogenicity in mice.

BACKGROUND AND OBJECTIVE: Porphyromonas gingivalis has been implicated as one of the major pathogens in chronic periodontitis, an infectious disease affecting the majority of the adult population. We have previously demonstrated that a surface protein, arginine deiminase (ArcA), of Streptococcus cristatus represses production of P. gingivalis long fimbriae and interrupts the formation of P. gingivalis biofilms in vitro. Our in vivo studies have also shown that the distribution of P. gingivalis and S. cristatus in human subgingival plaque is negatively correlated. The objective of this study was to determine if S. cristatus ArcA inhibits P. gingivalis colonization and attenuates its subsequent pathogenesis in alveolar bone loss in the murine oral cavity. MATERIAL AND METHODS: A wild-type strain of S. cristatus (CC5A) and its arcA knockout mutant (ArcAE) were used as initial colonizers in the oral cavity of BALB/cByJ mice. Colonization of P. gingivalis on the existing S. cristatus biofilms was assessed by quantitative PCR, and P. gingivalis-induced alveolar bone loss was measured 6 wk after P. gingivalis infection. RESULTS: The presence of S. cristatus CC5A, but not its arcA mutant, attenuated P. gingivalis colonization in the murine oral cavity. In addition, P. gingivalis-induced alveolar bone loss was significantly lower in mice initially infected with S. cristatus CC5A than in those infected with the arcA mutant. CONCLUSION: This study provides direct evidence that S. cristatus ArcA has an inhibitory effect on P. gingivalis colonization, which may in turn attenuate the pathogenicity of P. gingivalis.

[Consensus of experts on the oral health management and medical risk prevention for the patients with chronic airway diseases (2022 edition)].

Today, there is greater awareness on the association between oral diseases and respiration diseases after the outbreak of COVID-19. However, confusion regarding the oral health management and medical risk prevention for patients with chronic airway diseases has been remained among dental clinicians. Therefore, the dental experts of the Fifth General Dentistry Special Committee, Chinese Stomatological Association, combined with the experts of respiratory and critical care medicine, undertook the formation of consensus on the oral health management of patients with chronic airway diseases in order to help dental clinicians to evaluate medical risks and make better treatment decision in clinical practice. In the present consensus report, the relationship of oral diseases and chronic airway diseases, the oral health management and the treatment recommendations of patients with chronic airway diseases are provided.

[Consensus of experts on the medical risk prevention for the patients with cardiovascular diseases during dental treatment (2022 edition)].

With the aging process of population in the society, the prevalence of cardiovascular diseases (CVD) in China is increasing continuously and the number of dental patients with CVD is increasing gradually too. Due to the lack of guidelines for dental patients with CVD in our country, how to implement standardized preoperative evaluation and perioperative risk prevention remains a problem to be solved for dentists at present. The present expert consensus was reached by combining the clinical experiences of the expert group of the Fifth General Dentistry Special Committee, Chinese Stomatological Association and respiratory and cardiology experts in diagnosis and treatment for CVD patients, and by systematically summarizing the relevant international guidelines and literature regarding the relationship between CVD and oral diseases and the diagnosis and treatment of dental patients with heart failure, hypertension and antithrombotic therapy. The consensus aims to provide, for the dental clinicians, the criteria on diagnosis and treatment of CVD in dental patients in China so as to reduce the risk and complications, and finally to improve the treatment levels of dental patients with CVD in China.

Flocculation properties of a bioflocculant produced by Bacillus licheniformis.

Studies of the flocculation properties of bioflocculant combined with its structure characterization are helpful to develop more effective bioflocculant. This paper reports findings of our research on the flocculation properties of the bioflocculant ZS-7 in the kaolin suspension based on its structure characterization. With the addition of 2 mg/L ZS-7 and 9 mM CaCl(2), the optimum temperature for flocculation performance of ZS-7 in the kaolin suspension is about 30°C, giving the highest flocculating activity 99.2%. Studies of the flocculation properties revealed that it was stable at 60-100°C and pH 4-10. Moreover, it could flocculate a kaolin suspension over a wide range of pH (2-12) and temperatures (4-95°C) in the presence of CaCl(2).

The actin-driven movement and formation of acetylcholine receptor clusters.

A new method was devised to visualize actin polymerization induced by postsynaptic differentiation signals in cultured muscle cells. This entails masking myofibrillar filamentous (F)-actin with jasplakinolide, a cell-permeant F-actin-binding toxin, before synaptogenic stimulation, and then probing new actin assembly with fluorescent phalloidin. With this procedure, actin polymerization associated with newly induced acetylcholine receptor (AChR) clustering by heparin-binding growth-associated molecule-coated beads and by agrin was observed. The beads induced local F-actin assembly that colocalized with AChR clusters at bead-muscle contacts, whereas both the actin cytoskeleton and AChR clusters induced by bath agrin application were diffuse. By expressing a green fluorescent protein-coupled version of cortactin, a protein that binds to active F-actin, the dynamic nature of the actin cytoskeleton associated with new AChR clusters was revealed. In fact, the motive force generated by actin polymerization propelled the entire bead-induced AChR cluster with its attached bead to move in the plane of the membrane. In addition, actin polymerization is also necessary for the formation of both bead and agrin-induced AChR clusters as well as phosphotyrosine accumulation, as shown by their blockage by latrunculin A, a toxin that sequesters globular (G)-actin and prevents F-actin assembly. These results show that actin polymerization induced by synaptogenic signals is necessary for the movement and formation of AChR clusters and implicate a role of F-actin as a postsynaptic scaffold for the assembly of structural and signaling molecules in neuromuscular junction formation.

Dentine bond strength and microleakage of flowable composite, compomer and glass ionomer cement.

BACKGROUND: To assess in vitro the dentine bond strength and microleakage of three Class V restorations viz. flowable composite, compomer and glass ionomer cement. METHODS: Eighteen dentine specimens were prepared and randomly distributed among three groups. Three kinds of restoration materials were each bonded on prepared dentine surfaces in three groups as per the manufacturers' instructions. Group Aelite: Tyrian SPE (a no-rinse, self-priming etchant) + One Step Plus (an universal dental adhesive) + Aeliteflo (a flowable composite); Group Dyract: Prime & Bond NT (a no-rinse, self-priming dental adhesive) + Dyract AP (a compomer); Group GlasIonomer: GlasIonomer Type II (a self-cured restorative glass ionomer). Fifteen dentine/restoration microtensile bond test specimens were prepared from each group and were subjected to microtensile bond strength testing. The bond interfaces were observed morphologically using a scanning electron microscope (SEM). Twenty-four cervical cavities of 4.0 mm mesiodistal length, 2.0 mm occlusogingival height and 1.5 mm depth were prepared at the cemento-enamel junction (CEJ) on both buccal and lingual surfaces of each tooth. The cavities were each filled with flowable composite (Group Aelite), compomer (Group Dyract) and glass ionomer cement (Group GlasIonomer) using the same material and methods as for the microtensile bond tests. Microleakage of each restoration was evaluated by the ratio of the length of methylene blue penetration along the tooth-restoration interface and the total length of the dentine cavity wall on the cut surface. RESULTS: One-way ANOVA and least significant difference (LSD) tests revealed statistically significant differences among the dentine bond strength for Group Aelite (28.4 MPa), Group Dyract (15.1 MPa) and Group GlasIonomer (2.5 MPa). SEM images showed intimate adaptation in the restoration/dentine interfaces of Group Aelite and Group Dyract. All of the systems tested in this study presented microleakage. However, both Group Aelite (0.808) and Group Dyract (0.863) had significantly less microleakage than Group GlasIonomer (0.964). There were no statistically significant microleakage differences between Group Aelite and Group Dyract, and no statistically significant microleakage differences between the occlusal margin and gingival margin. CONCLUSIONS: None of the systems tested in this study completely eliminated microleakage. However, both the flowable composite and compomer provided stronger dentine bond strengths and better margin sealing than the conventional glass ionomer cement. Occlusal forces exerted the same effects on microleakage of the occlusal margin and gingival margin in cervical cavities.

Functional Odontoblastic-Like Cells Derived from Human iPSCs.

The induced pluripotent stem cells (iPSCs) have an intrinsic capability for indefinite self-renewal and large-scale expansion and can differentiate into all types of cells. Here, we tested the potential of iPSCs from dental pulp stem cells (DPSCs) to differentiate into functional odontoblasts. DPSCs were reprogrammed into iPSCs via electroporation of reprogramming factors OCT-4, SOX2, KLF4, LIN28, and L-MYC. The iPSCs presented overexpression of the reprogramming genes and high protein expressions of alkaline phosphatase, OCT4, and TRA-1-60 in vitro and generated tissues from 3 germ layers in vivo. Dentin discs with poly-L-lactic acid scaffolds containing iPSCs were implanted subcutaneously into immunodeficient mice. After 28 d from implantation, the iPSCs generated a pulp-like tissue with the presence of tubular dentin in vivo. The differentiation potential after long-term expansion was assessed in vitro. iPSCs and DPSCs of passages 4 and 14 were treated with either odontogenic medium or extract of bioactive cement for 28 d. Regardless of the passage tested, iPSCs expressed putative markers of odontoblastic differentiation and kept the same mineralization potential, while DPSC P14 failed to do the same. Analysis of these data collectively demonstrates that human iPSCs can be a source to derive human odontoblasts for dental pulp research and test bioactivity of materials.

The effects of water on degradation of the zirconia-resin bond.

OBJECTIVES: 10-methacryloyloxydecyldihydrogenphosphate (MDP) containing primers improve bonding of yttria-stabilised tetragonal zirconia (Y-TZP) to methacrylate resins. The present study investigated the role played by water in the deterioration of MDP-mediated zirconia-resin bonds. METHODS: Grit-blasted Y-TZP plates were conditioned with two MDP primers and bonded with resin for shear bond strength (SBS) testing. Additional bonded plates were aged hydrothermally and compared with unaged Y-TZP after 24h of water-storage or 6 months of water/acid/alkali-storage. The monoclinic phase (m-ZrO2) in different groups was determined by X-ray diffraction. Hydrolytic stability of the coordinate bond between MDP and zirconia in neutral/acid/alkaline environment was analysed using thermodynamic calculations. Microleakage and release of the element phosphorus from MDP-mediated Y-TZP/resin-bonded interfaces were evaluated via methylene blue dye infiltration and inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS: Hydrothermal ageing did not significantly alter SBS. Ageing in acidic or neutral medium led to significant decline in SBS. The m-ZrO2 phase increased after hydrothermal ageing but no m-ZrO2 was detected in the water/acid/alkali-aged specimens. A higher equilibrium constant was identified in the MDP-t-ZrO2 complex when compared with the MDP-m-ZrO2 complex. MDP-conditioning failed to prevent infiltration of the methylene blue dye. Phosphorus was detected by ICP-MS from the solutions used for soaking the resin-bonded specimens. CONCLUSIONS: Hydrolysis of the coordinate bond between MDP and ZrO2, rather than t→m phase transformation, weakens the bond integrity between MDP-conditioned Y-TZP and methacrylate resin. CLINICAL SIGNIFICANCE: Hydrolysis of the coordinate bond between MDP and zirconia is responsible for deterioration of the integrity of the bond between MDP-conditioned Y-TZP and methacrylate resin.

Controlled-release mitomycin C-polylactic acid film prevents epidural scar hyperplasia after laminectomy by inducing fibroblast autophagy and regulating the expression of miRNAs.

OBJECTIVE: To design a new controlled-release MMC-PLA film and explore whether and how this film could prevent epidural scar hyperplasia and adhesion in a post-laminectomy rat model. MATERIALS AND METHODS: All procedures were performed under the approval and supervision of the Institutional Animal Care and Use Committee (IACUC) of Nanjing Medical University. A total of 120 Sprague-Dawley (SD) rats were randomly placed into four groups after laminectomy (each group=30 rats). In Group I, the laminectomy area was flushed with saline as a control; in Group II, 25 mg of PLA film was applied to the dura mater in the laminectomy area; in Group III, a cotton pad soaked with 0.01% MMC solution was kept on the laminectomy area; and in Group IV, 25 mg of PLA film containing 0.01% MMC was implanted on the laminectomy area. Magnetic resonance imaging (MRI), hematoxylin-eosin (HE) staining and Masson staining were used to evaluate scar adhesion and collagen deposition one month after the operation. Autophagy-related proteins, including autophagy-related gene 5 (ATG5), beclin 1, light chain-3B-2/1 (LC3B-2/1) and protein 53 (p53), were detected by Western blotting. A microRNA microarray analysis was performed to screen for scar tissue miRNAs, especially those associated with autophagy, and changes in expression were confirmed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: A total of 112 rats recovered uneventfully from the surgery. MRI showed that the scar adhesion and scar area of the MMC-PLA group were significantly reduced compared with those of the PLA, MMC, and saline groups. Accordingly, scar adhesion and the deposition of collagen in the rats treated with MMC-PLA were also significantly reduced, as indicated by HE and Masson staining. In the scar tissue, the levels of autophagy-related proteins (ATG5, beclin 1, LC3B-2/1 and p53) were significantly elevated in the MMC-PLA group. Additionally, in the MMC-PLA group, the expression levels of miR-34a, miR-146a and miR-200 were significantly increased, while the levels of miR-16, miR-221 and miR-378a were significantly decreased. CONCLUSIONS: The controlled-release MMC-PLA film could alleviate epidural scar hyperplasia after laminectomy; this outcome might be associated with increased autophagy and altered expression of miRNAs in the scar tissue.

Chlorhexidine Nanocapsule Drug Delivery Approach to the Resin-Dentin Interface.

In this study, we are introducing a new drug-delivery approach to demineralized dentin substrates through microsized dentinal tubules in the form of drug-loaded nanocapsules. Chlorhexidine (CHX) is widely used in adhesive dentistry due to its nonspecific matrix metalloproteinase inhibitory effect and antibacterial activities. Poly(ε-caprolactone) nanocapsules (nano-PCL) loaded with CHX were fabricated by interfacial polymer deposition at PCL/CHX ratios of 125:10, 125:25, and 125:50. Unloaded nanocapsules (blank) were fabricated as control. The fabricated nanocapsules were characterized in vitro in terms of particle size, surface charges, particle recovery, encapsulation efficiency, and drug loading. Nanocapsule morphology, drug inclusion, structural properties, and crystallinity were investigated by scanning and transmission electron microscopes (SEM/TEM), energy-dispersive x-ray analysis, Fourier transform infrared spectroscopy, and x-ray diffraction. Initial screening of the antibacterial activities and the cytotoxicity of the nanocapsules were also conducted. Nanocapsules, as carried on ethanol/water solution, were delivered to demineralized dentin specimens connected to an ex vivo model setup simulating the pulpal pressure to study their infiltration, penetration depth, and retention inside the dentinal tubules by SEM/TEM. Nanocapsules were Ag labeled and delivered to demineralized dentin, followed by the application of a 2-step etch-and-rinse dentin adhesive. CHX-release profiles were characterized in vitro and ex vivo up to 25 d. Spherical nanocapsules were fabricated with a CHX core coated with a thin PCL shell. The blank nanocapsules exhibited the largest z-average diameter with negatively charged ζ-potential. With CHX incorporation, the nanocapsule size was decreased with a positive shift in ζ-potential. Nano-PCL/CHX at 125:50 showed the highest drug loading, antibacterial effect, and CHX release both in vitro and ex vivo. SEM and TEM revealed the deep penetration and retention of the CHX-loaded nanocapsules inside dentinal tubules and their ability to be gradually degraded to release CHX in vitro and ex vivo. Ag-labeled nanocapsules revealed the close association and even distribution of nanocapsules throughout the resin tag structure. This study demonstrated the potential of introducing this novel drug-delivery approach to demineralized dentin substrates and the resin-dentin interface with nanosized CHX-loaded nanocapsules through the microsized dentinal tubules.

Biogenesis and function of Porphyromonas gingivalis outer membrane vesicles.

Porphyromonas gingivalis is one of the keystone pathogens associated with chronic periodontitis. All P. gingivalis strains examined thus far produce outer membrane vesicles. Recent studies have found that vesicles possess some well-known virulence factors of P. gingivalis such as adhesins, toxins and proteolytic enzymes. Carrying most of the characteristic features of their parent P. gingivalis cells, vesicles communicate with host cells and other members of microbial biofilms, resulting in the transmission of virulence factors into these host cells and the formation of pathogenic bacteria-dominated microbial communities. An in-depth understanding of both the nature and role of vesicles in the pathogenicity of P. gingivalis is both important and timely, particularly when speaking of periodontitis and its related systemic effects.

Bonding of universal adhesives to dentine--Old wine in new bottles?

OBJECTIVE: Multi-mode universal adhesives offer clinicians the choice of using the etch-and-rinse technique, selective enamel etch technique or self-etch technique to bond to tooth substrates. The present study examined the short-term in vitro performance of five universal adhesives bonded to human coronal dentine. METHODS: Two hundred non-carious human third molars were assigned to five groups based on the type of the universal adhesives (Prime&Bond Elect, Scotchbond Universal, All-Bond Universal, Clearfil Universal Bond and Futurabond U). Two bonding modes (etch-and-rinse and self-etch) were employed for each adhesive group. Bonded specimens were stored in deionized water for 24h or underwent a 10,000-cycle thermocycling ageing process prior to testing (N=10). Microtensile bond testing (µTBS), transmission electron microscopy (TEM) of resin-dentine interfaces in non-thermocycled specimens and scanning electron microscopy (SEM) of tracer-infused water-rich zones within hybrid layers of thermocycled specimens were performed. RESULTS: Both adhesive type and testing condition (with/without thermocycling) have significant influences on µTBS. The use of each adhesive in either the etch-and-rinse or self-etch application mode did not result in significantly different µTBS to dentine. Hybrid layers created by these adhesives in the etch-and-rinse bonding mode and self-etch bonding mode were ∼5µm and ≤0.5µm thick respectively. Tracer-infused regions could be identified within the resin-dentine interface from all the specimens prepared. CONCLUSION: The increase in versatility of universal adhesives is not accompanied by technological advances for overcoming the challenges associated with previous generations of adhesives. Therapeutic adhesives with bio-protective and bio-promoting effects are still lacking in commercialized adhesives. CLINICAL SIGNIFICANCE: Universal adhesives represent manufacturers' attempt to introduce versatility in product design via adaptation of a single-bottle self-etch adhesive for other application modes without compromising its bonding effectiveness.

The effects of streptozotocin diabetes on salivary-mediated bacterial aggregation and adherence.

Diabetic rats are known to have an increased susceptibility to dental caries and major alterations in parotid salivary composition. Salivary proteins play an important part in oral health maintenance; thus specific changes in salivary protein composition in diabetic animals might alter the ecological balance in favour of cariogenic bacteria, and toward the initiation and progression of the disease process. The ability of whole, parotid and submandibular salivas from control and streptozotocin-diabetic rats to mediate the aggregation and adherence to hydroxyapatite of mutans streptococci was examined. Salivary-mediated bacterial aggregating activity was significantly reduced in whole and parotid salivas from diabetic rats, but bacterial adherence to hydroxyapatite was unaffected. The aggregating and adherence activities of rat whole saliva were derived mainly from parotid saliva, which contains predominantly low molecular-weight proteins and glycoproteins (< 200 kDa), but rat parotid saliva was capable of interacting with the bacterial receptor for the high molecular-weight aggregating factor in human saliva. SDS-PAGE of parotid saliva revealed that a number of proteins, including the basic and acid proline-rich proteins, were altered in the salivas of diabetic animals. After incubation with either Streptococcus mutans or hydroxyapatite several protein bands were depleted, and thus a variety of proteins and glycoproteins may be responsible for the adherence and aggregating activity of rat parotid saliva.

An in vitro study on roughening of the metal surface with lost crystal salts to increase the metal-resin bond strength.

Good mechanical retention between metal and resin or luting agent can be obtained by roughening the metal surface with lost crystal salts. The relationship of metal-resin bond strength to the shape and size of the crystals was studied. The results indicated that cuboid crystal salts provided the best roughening among the tested crystal shapes (cube, irregular, spherical, and cuboid). There was no relationship between the tensile bond strength and the size of the crystals. Furthermore, the bending strength of metal coated with resin was improved by the roughening of the metal surface.