[Analysis of non-alcoholic fatty liver disease differences from metabolic dysfunction-associated fatty liver disease based on clinical features].

Objective: To explore the clinical features of fatty liver disease (FLD) from non-alcoholic fatty liver disease (NAFLD) to metabolic dysfunction-associated fatty liver disease (MASLD), so as to elucidate its clinical application value under three renames. Methods: Patients who were hospitalized in the Department of Hepatology, Hospital of Traditional Chinese Medicine Affiliated to Xinjiang Medical University, from January 2020 to September 2023 and met the diagnosis of NAFLD, metabolic-associated fatty liver disease (MAFLD), or MASLD were selected as the research subjects. The clinical indicators differences among the three groups of patients were compared, mainly including general information (age, gender, body mass index, past history, etc.), serological indicators (liver and kidney function, blood lipids, blood sugar, coagulation function, etc.), non-invasive liver fibrosis indicators, fat attenuation parameters, etc. Measurement data were analyzed using ANOVA and the rank sum test, while count data were analyzed using the χ(2) test. Results: NAFLD, MAFLD, and MASLD prevalence rates among 536 cases were 64.0%, 93.7%, and 100%, respectively. 318 cases (59.3%) met the three fatty liver names at the same time among them. Male population proportions in NAFLD, MAFLD, and MASLD were 30.9%, 55.8%, and 53.9%, respectively. The alcohol consumption history proportion was 0, 36.7%, and 36.0%, respectively. The smoking history proportion was 7.0%, 31.9%, and 30.6%, respectively. The body mass index was (27.66 ± 3.97), (28.33 ± 3.63), and (27.90 ± 3.89) kg/m(2), respectively. The γ-glutamyltransferase levels were 26.6 (18.0, 47.0) U/L, 31.0 (20.0, 53.0) U/L, and 30.8 (19.8, 30.8) U/L, respectively. The high-density lipoprotein cholesterol levels were 1.07 (0.90, 1.23) mmol/L, 1.02 (0.86, 1.19) mmol/L, and 1.03 (0.87,1.21) mmol/L, respectively. Sequentially measured uric acid was (322.98 ± 84.51) µmol/L, (346.57 ± 89.49) µmol/L, and (344.89 ±89.67) µmol/L, respectively. Sequentially measured creatinine was 69.6 (62.9, 79.0) µmol/L, 73.0 (65.0, 83.5) µmol/L, and 73.0 (65.0, 83.0) µmol/L, respectively. The sequential analysis of obesity proportion was 74.3%, 81.7%, and 76.5%, respectively, with statistically significant differences (P<0.05). Conclusion: Compared with the NAFLD population, the MAFLD and MASLD populations were predominantly male, obese, and had a history of smoking and drinking. The levels of γ-glutamyltransferase, uric acid, and creatinine were slightly higher, while the levels of high-density lipoprotein cholesterol were lower. MASLD appeared in NAFLD and MAFLD on the basis of inheritance and progression, emphasizing once again the important role of metabolic factors in a fatty liver.

[A two-dimensional photographic and three-dimensional digital dental model comparative analysis in maxillary anterior teeth].

Objective: To assess the accuracy of two-dimensional (2D) photographs in measuring esthetic parameters of the maxillary anterior teeth by comparing them with measurements obtained from three-dimensional (3D) dental models. Methods: A total of one hundred volunteers (49 males, 51 females, aged 18-23 years) were recruited from School and Hospital of Stomatology, Wuhan University from January to February 2024. 3D digital models of their dentitions were obtained using an intraoral scanner, and standardized frontal 2D intraoral photographs were captured with a digital camera. The lengths, widths and width/length ratio of the bilateral incisors, lateral incisors and canines were measured on both the 3D digital models and the 2D intraoral photographs. The width ratios of adjacent maxillary anterior were also calculated on the 2D intraoral photographs and the frontal view of 3D digital models. Results: The widths of lateral incisors [(5.85±0.60) mm] and canines [(4.73±0.71) mm] and the lengths of canines [(8.72±0.96) mm] in the 2D intraoral photographs were significantly lower than those in 3D digital models [(6.65±0.59), (7.76±0.60), (8.90±0.86) mm] (t=-18.24, P<0.001; t=-54.43, P<0.001; t=-4.40, P<0.001), while there were no significant differences in the lengths and widths of the other teeth (P>0.05). The width/length ratios measured from the 2D intraoral photographs for the lateral incisors and canines (0.74±0.08, 0.55±0.08) were significantly lower than those measured in the 3D digital models (0.84±0.09, 0.88±0.09) (t=-19.68, P<0.001; t=-50.21, P<0.001), and the width/length ratio of the central incisors showed no significant difference between the two groups (P>0.05). The width ratios of canines/lateral incisors and lateral incisors/central incisors measured on the 2D intraoral photographs (0.72±0.06, 0.85±0.11) were significantly smaller than those measured in the frontal view of 3D digital models (0.75±0.06, 0.89±0.11) (t=-9.31, P<0.001; t=-6.58, P<0.001). Conclusions: There is a difference between 2D and 3D measurement results of teeth in the esthetic area and the magnitude of the difference varies with their position in the dental arch. When analyzing the measurement of the anterior teeth, it is necessary to choose the appropriate method according to the target tooth position.

DPSCs regulate epithelial-T cell interactions in oral submucous fibrosis.

BACKGROUND: Oral submucous fibrosis (OSF) is a precancerous lesion characterized by fibrous tissue deposition, the incidence of which correlates positively with the frequency of betel nut chewing. Prolonged betel nut chewing can damage the integrity of the oral mucosal epithelium, leading to chronic inflammation and local immunological derangement. However, currently, the underlying cellular events driving fibrogenesis and dysfunction are incompletely understood, such that OSF has few treatment options with limited therapeutic effectiveness. Dental pulp stem cells (DPSCs) have been recognized for their anti-inflammatory and anti-fibrosis capabilities, making them promising candidates to treat a range of immune, inflammatory, and fibrotic diseases. However, the application of DPSCs in OSF is inconclusive. Therefore, this study aimed to explore the pathogenic mechanism of OSF and, based on this, to explore new treatment options. METHODS: A human cell atlas of oral mucosal tissues was compiled using single-cell RNA sequencing to delve into the underlying mechanisms. Epithelial cells were reclustered to observe the heterogeneity of OSF epithelial cells and their communication with immune cells. The results were validated in vitro, in clinicopathological sections, and in animal models. In vivo, the therapeutic effect and mechanism of DPSCs were characterized by histological staining, immunohistochemical staining, scanning electron microscopy, and atomic force microscopy. RESULTS: A unique epithelial cell population, Epi1.2, with proinflammatory and profibrotic functions, was predominantly found in OSF. Epi1.2 cells also induced the fibrotic process in fibroblasts by interacting with T cells through receptor-ligand crosstalk between macrophage migration inhibitory factor (MIF)-CD74 and C-X-C motif chemokine receptor 4 (CXCR4). Furthermore, we developed OSF animal models and simulated the clinical local injection process in the rat buccal mucosa using DPSCs to assess their therapeutic impact and mechanism. In the OSF rat model, DPSCs demonstrated superior therapeutic effects compared with the positive control (glucocorticoids), including reducing collagen deposition and promoting blood vessel regeneration. DPSCs mediated immune homeostasis primarily by regulating the numbers of KRT19 + MIF + epithelial cells and via epithelial-stromal crosstalk. CONCLUSIONS: Given the current ambiguity surrounding the cause of OSF and the limited treatment options available, our study reveals that epithelial cells and their crosstalk with T cells play an important role in the mechanism of OSF and suggests the therapeutic promise of DPSCs.

High-Performance Dental Resins Containing a Starburst Monomer.

Dimethacrylate-based chemistries feature extensively as resin monomers in dental resin-based materials due to their distinguished overall performance. However, challenges endure, encompassing inadequate mechanical attributes, volumetric shrinkage, and estrogenicity. Herein, we first synthesized a novel resin monomer, 9-armed starburst polyurethane acrylate (NPUA), via the grafting-onto approach. Compared to the primary commercial dental monomer 2,2-bis [p-(2'-hydroxy-3'-methacryloxypropoxy) phenyl] propane (Bis-GMA) (with a viscosity of 1,174 ± 3 Pa·s and volumetric shrinkage of 4.7% ± 0.1%), the NPUA monomer achieves the lower viscosity (158 ± 1 Pa·s), volumetric shrinkage (2.5% ± 0.1%), and cytotoxicity (P < 0.05). The NPUA-based resins exhibit the higher flexural strength, flexural modulus, hardness, and hydrophobicity and lower volumetric shrinkage, water absorption, and solubility compared to the Bis-GMA (70 wt%)/TEGDMA (30 wt%) resins. The NPUA-based composites exhibit significantly higher flexural strength, flexural modulus, and hardness and lower volumetric shrinkage (171.4 ± 3.0 MPa, 12.6 ± 0.5 GPa, 2.0 ± 0.2 GPa, and 3.4% ± 0.2%, respectively) compared to the Bis-GMA group (120.3 ± 4.7 MPa, 9.4 ± 0.7 GPa, 1.5 ± 0.1 GPa, and 4.7% ± 0.2%, respectively; P < 0.05). This work presents a viable avenue for augmenting the physicochemical attributes of dental resins.

Enhanced Bonding to Caries-Affected Dentin Using an Isocyanate-Based Primer.

Dental caries is the most common oral disease and the most common cause of resin restorations. In minimally invasive dentistry, the principle behind cavity preparation is to remove external caries-infected dentin (CID) and preserve internal caries-affected dentin (CAD) and sound dentin (SD). The cavity floor is mainly composed of CAD, but the poor bonding performance of CAD has become a widespread concern. This study evaluated the performance of a new collagen-reactive monomer (ITCM) used as a primer to improve the bonding performance of CAD. The experimental specimens were grouped as follows: SD, CAD, and ITCM-pretreated CAD (CAD-ITCM). Dentin slices were obtained for attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis. The bonded samples were subjected to microtensile bond strength analysis after 24 h of water storage or aging by thermocycling, and the bonding interface quality was evaluated by nanoleakage assessment, interfacial nanoindentation testing, and in situ zymography. Cytotoxicity experiments with ITCM were performed. ATR-FTIR showed that the isocyanate groups in ITCM can covalently bind and form hydrogen bonds with the collagen in CAD to mediate chemical bonding. ITCM pretreatment significantly improved the bond strength of CAD (P < 0.05), reduced interfacial nanoleakage, improved the sealing of the bonding interface, enhanced the homogeneity of the hybrid layer, and inhibited matrix metalloproteinase activity. In addition, ITCM presented acceptable biocompatibility for dental restorative application. Taken together, this study reported the application of ITCM to induce collagen-based chemical bonding in the CAD bonding system, which fills the gap in strategies to improve the bonding performance of CAD immediately and after aging and has important clinical application prospects.

[Analysis of intestinal microbial diversity in Leopoldamys edwardsi based on illumina sequencing technique].

To explore the composition and diversity of the intestinal microflora of Leopoldamys edwardsi in Hainan Island. In November 2019, DNA was extracted from fecal samples of 25 adult Leopoldamys edwardsi (14 males and 11 females) in Hainan Island at the Joint Laboratory of tropical infectious diseases of Hainan Medical College and Hong Kong University. Based on the IonS5TMXL sequencing platform, single-end sequencing (Single-End) was used to construct a small fragment library for single-end sequencing. Based on Reads shear filtration and OTUs clustering. The species annotation and abundance analysis of OTUs were carried out by using mothur method and SSUrRNA database, and further conducted α diversity and ß diversity analysis. A total of 1481842 high quality sequences, belonging to 14 Phyla, 85 families and 186 Genera, were obtained from 25 intestinal excrement samples of Leopoldamys edwardsi. At the level of phyla classification, the main core biota of the Leopoldamys edwardsi contained Firmicutes (46.04%),Bacteroidetes (25.34%), Proteobacteria (17.09%), Tenericutes (7.38%) and Actinobacteria (1.67%), these five phyla account for 97.52% of all phyla. The ratio of Helicobacter which occupied the largest proportion at the genus level was 12.44%, followed by Lactobacillus (11.39%), Clostridium (6.19%),Mycoplasma (4.23%) and Flavonifractor (3.52%). High throughput sequencing analysis showed that the intestinal flora of Leopoldamys edwardsi in Hainan Island was complex and diverse, which had the significance of further research.

Applications of Cryogenic Electron Microscopy in Biomineralization Research.

Biological mineralization is a natural process manifested by living organisms in which inorganic minerals crystallize under the scrupulous control of biomolecules, producing hierarchical organic-inorganic composite structures with physical properties and design that galvanize even the most ardent structural engineer and architect. Understanding the mechanisms that control the formation of biominerals is challenging in the biomimetic engineering of hard tissues. In this regard, the contribution of cryogenic electron microscopy (cryo-EM) has been nothing short of phenomenal. By preserving materials in their native hydrated status and reducing damage caused by ion beam radiation, cryo-EM outperforms conventional transmission electron microscopy in its ability to directly observe the morphologic evolution of mineral precursor phases at different stages of biomineralization with nanoscale spatial resolution and subsecond temporal resolution in 2 or 3 dimensions. In the present review, the development and applications of cryo-EM are discussed to support the use of this powerful technique in dental research. Because of the rapid development of cryogenic sample preparation techniques, direct electron detection, and image-processing algorithms, the last decade has witnessed an exponential increase in the use of cryo-EM in structural biology and materials research. By amalgamating with other analytic techniques, cryo-EM may be used for qualitative and quantitative analyses of the kinetics and thermodynamic mechanisms in which organic macromolecules participate in the transformation of mineral precursors from their original liquid state to amorphous and ultimately crystalline phases. The present review concentrates on the biomineralization of calcium phosphate mineral phases, while that of calcium carbonate, silica, and magnetite is only briefly mentioned. Bioinspired organic matrix-mediated inorganic crystallization strategies are discussed from the perspective of tissue regeneration engineering.

[Prospective clinical study on the influence of implant crown and bridge prostheses characteristics on peri-implant disease].

Objective: To investigate the influence of different characteristics of implant-supported fixed dental prostheses on the incidence of peri-implant disease. Methods: Prospective cohort was established for patients who received implant-supported fixed dental prostheses at the Department of Prosthodontics, School of Stomatology, The Fourth Military Medical University between June 2014 and September 2015. Several patient-related factors, implant prostheses factors, and oral hygiene maintenance factors were collected. The Log-rank test was used to compare the peri-implant disease rates of various factors, and the Cox proportional hazards model was used to conduct multivariate study on single factor significant factors to analyze the impact on the incidence of peri-implant disease. Results: A total of 214 subjects and 351 implants were included in the cohort, the follow-up period was (11.0±3.5) months. Finally, 43.0% (92/214) of patients and 37.3% (131/351) of implants developed peri-implant diseases. The incidence of peri-implant mucositis and peri-implantitis was 41.1% (88/214) and 4.2% (9/214) at the subject level,and 34.2% (120/351) and 3.1% (11/351) at the implant level. Among the factors associated with the implant prosthesis, single factor Log-rank analysis showed that prostheses retention methods, proximal contact of the prostheses, occlusion situation were statistical significance (P<0.05). Multivariate analysis using Cox proportional hazards model showed that screw retention (hazard ratio=2.38, 95%CI: 1.42-3.99), proximal contact loss of the prostheses (hazard ratio=2.36, 95%CI: 1.31-4.27) were independent risk factors for peri-implant disease (P<0.05). Conclusions: Factors such as prostheses retention mode and proximal contact characteristics have important influence on the health status of the implant.

A novel dentin bonding scheme based on extrafibrillar demineralization combined with covalent adhesion using a dry-bonding technique.

Dentin bonding is a dynamic process that involves the penetration of adhesive resin monomers into the extrafibrillar and intrafibrillar demineralized collagen matrix using a wet-bonding technique. However, adhesive resin monomers lack the capacity to infiltrate the intrafibrillar space, and the excess water that is introduced by the wet-bonding technique remains at the bonding interface. This imperfectly bonded interface is inclined to hydrolytic degradation, severely jeopardizing the longevity of bonded clinical restorations. The present study introduces a dentin bonding scheme based on a dry-bonding technique, combined with the use of extrafibrillar demineralization and a collagen-reactive monomer (CRM)-based adhesive (CBA). Selective extrafibrillar demineralization was achieved using 1-wt% high-molecular weight (MW) carboxymethyl chitosan (CMCS) within a clinically acceptable timeframe to create a less aggressive bonding substance for dentin bonding due to its selectively extrafibrillar demineralization capacity. CMCS demineralization decreased the activation of in situ collagenase, improved the shrinking resistance of demineralized collagen, and thus provided stronger and more durable bonding than traditional phosphoric acid etching. The new dentin bonding scheme that contained CMCS and CBA and used a dry-bonding technique achieved an encouraging dentin bonding strength and durability with low technical sensitivity. This bonding scheme can be used to improve the stability of the resin-dentin interface and foster the longevity of bonded clinical restorations.

[Advances in color stability of resin cements and its influence on all-ceramics restorations].

Resin cements have been widely employed for bonding all-ceramic restorations in clinical practice, its color stability is directly related to long-term prosthetic effect of restorations. Discoloration of resin cements can be attributed to two causes: endogenous factors are generally related to material compositions and initiation mechanism of polymerization; exogenous factors are mainly related to stimulation of local oral environment. Color stability of resin cements has close relationship with esthetic effect of all-ceramic restorations. The aim of this literature review was to make a presentation and discussion systematically about color stability of resin cements commonly used clinically, its influence factors and influence on all-ceramic restorations, so as to provide a reference for the application of all-ceramic restorations.

Isocyanate-terminated urethane-based methacrylate for in situ collagen scaffold modification.

When damaged or fractured collagen-rich hard tissues are repaired by resin material, the collagen matrix may be used as a scaffold, after removal of the natural minerals, for resin monomers to penetrate and polymerize in-situ. Formation of a collagen-polymer hybrid biocomposite via mechanical hybridization provides a stable and strong link between endogenous tissue and the prosthesis for successful clinical integration. However, the heterogeneity between hydrophobic resin polymers and hydrophilic collagen presents a challenge to the quality of hybrid biocomposite. The objective of the present study was to evaluate the potential benefits of a collagen-reactive monomer (CRM, an isocyanate-terminated urethane-based methacrylate) with covalent affinity to collagen as "chemical link" to enhance in-situ resin hybridization within a collagen scaffold. Here, the CRM ligand with active isocyanate group may be chemically grafted onto the collagen receptor via covalent and hydrogen bonds. Dentin-derived collagen chemical modified by CRM shows improved mechanical property, thermostability and enzymatic stability. Moreover, CRM inhibited both exogenous and endogenous collagenase activities. The modification of collagen by chemical grafting of resin monomers improved its mechanical and physicochemical properties and demonstrated the potential of CRM for use in promoting chemical adhesion and creating a much stronger and durable bonding interface. Formation of a chemical bond between polymer and collagen scaffold in-situ improves the mechanical performance of collagen and may create a much stronger and durable collagen-polymer hybrid material. Addition of CRM into adhesives might effectively prolong the longevity of clinical resin-bonded restorations.

Evaluation of a Collagen-Reactive Monomer with Advanced Bonding Durability.

This study evaluated the use of a new collagen-reactive monomer (CRM), isocyanate-terminated urethane methacrylate precursor, which has covalent affinity to dental collagen, in the formation of dentin-resin bonds and compared it with 2 other dental adhesives. Dentin specimens were bonded with either the CRM-based adhesive (CBA), One-Step (OS; Bisco, Inc.), or a negative adhesive (NA) control and subjected to 24-h storage in water, thermocycling to simulate 1-y clinical function, or a matrix metalloproteinase-mediated aging process. We tested the microtensile bond strength (µTBS), characterized the bonding interface with an atomic force microscope, conducted micro-Raman analysis, and performed leakage tests and in situ zymography. CBA and OS exhibited comparable bonding strength after 24 h (P > 0.05); however, there was a sharp decrease in µTBS after aging for all except CBA (P < 0.001). Raman spectra results indicated increased collagen crosslinking and chemical reaction between the adhesive and collagen in the CBA group. CBA achieved high-quality hybridization with collagen, improving mechanical properties and integrity, and decreased the enzyme-mediated degradation of the bonding interface by inhibiting collagenolytic activity. With the promising bonding durability of coapplied CBA, CRM may be the first dental adhesive to provide strong and long-lasting resin-dental collagen bonding without the additional conditioning step. The use of CBA results in high-quality hybrid layers that protect the resin-dentin interface from harmful biological and chemical activities commonly occurring in the oral environment.

Improving the wear performance of feldspathic veneering porcelain by ion-exchange strengthening.

OBJECTIVES: The present study examined the effects of Na+→K+ ion-exchange on the wear performance of feldspathic veneering porcelain. METHODS: Bar and disk specimens were prepared using IPS classic as the feldspathic veneering porcelain. After ion-exchange by immersion of the specimens in melted KNO3 at two temperatures for different time-periods, the bars were tested for flexural strength and Vickers surface hardness. The disks were paired with zirconia antagonists and tested with a pin-on-disk tribometer with 10 N for 70☓104 wear cycles in artificial saliva. Wear analysis of the porcelain and zirconia was performed using 3D profilometer and analysed with one-way analysis of variance and Tukey's post-hoc pairwise comparison procedures. Worn surfaces were examined with scanning electron microscopy. RESULTS: The feldspathic veneering porcelain exhibited strong time-dependent wear behaviour, with typical running-in and steady wear stages. Ion-exchange treatments at 380 °C and 440 °C both enhanced the mechanical properties, decreased the wear rates of running-in wear and steady wear. The wear performance of porcelain treated by ion-exchange at lower temperature (380 °C) was improved significantly, especially reducing the wear rate of the running-in stage. CONCLUSION: A thicker ion-exchange layer with less stress relaxation may be obtained by ion-exchange at lower exchange temperature for a long processing time. Such a protocol improves the wear performance of the porcelain effectively. CLINICAL SIGNIFICANCE: Restorations with veneering porcelain may fail prematurely due to excessive wear. It important to improve the wear performance of the porcelain. Ion-exchange has the potential to strengthen dental veneering porcelain. Understanding the effect of ion-exchange on the wear performance of porcelain provides insight improving the wear performance of these restorations.

Contribution of biomimetic collagen-ligand interaction to intrafibrillar mineralization.

Contemporary models of intrafibrillar mineralization mechanisms are established using collagen fibrils as templates without considering the contribution from collagen-bound apatite nucleation inhibitors. However, collagen matrices destined for mineralization in vertebrates contain bound matrix proteins for intrafibrillar mineralization. Negatively charged, high-molecular weight polycarboxylic acid is cross-linked to reconstituted collagen to create a model for examining the contribution of collagen-ligand interaction to intrafibrillar mineralization. Cryogenic electron microscopy and molecular dynamics simulation show that, after cross-linking to collagen, the bound polyelectrolyte caches prenucleation cluster singlets into chain-like aggregates along the fibrillar surface to increase the pool of mineralization precursors available for intrafibrillar mineralization. Higher-quality mineralized scaffolds with better biomechanical properties are achieved compared with mineralization of unmodified scaffolds in polyelectrolyte-stabilized mineralization solution. Collagen-ligand interaction provides insights on the genesis of heterogeneously mineralized tissues and the potential causes of ectopic calcification in nonmineralized body tissues.

Chitosan-Based Extrafibrillar Demineralization for Dentin Bonding.

Instability of resin-dentin bonds is the Achilles' heel of adhesive dentistry. To address this problem, a chelate-and-rinse extrafibrillar dentin demineralization strategy has been developed that keeps intrafibrillar minerals within collagen fibrils intact to prevent activation of endogenous proteases that are responsible for collagen degradation within hybrid layers. The objective of the present study was to evaluate the potential of using chitosan >40 kDa as an antimicrobial extrafibrillar dentin-chelating agent to enhance bond durability. Transmission electron microscopy provided evidence for retention of intrafibrillar minerals and smear plugs in dentin conditioned with 1 wt% chitosan. Analyzed by Kruskal-Wallis analysis of variance, Dunn's statistic, and separate Mann-Whitney tests, tensile bond strengths to wet- and dry-bonded dentin indicated that chelating dentin with chitosan for 60 s prior to bonding did not result in a significant decline in resin-dentin bond strength when compared with that of phosphoric acid etching ( P > 0.05). Gelatinolytic activity within the hybrid layers was examined via in situ zymography after 24-h storage or after thermomechanical cycling and analyzed with 3-factor analysis of variance. After 24 h, enzymatic activity was detected only within completely demineralized phosphoric acid-etched dentin, with values derived from dry bonding significantly higher than those derived from wet bonding ( P < 0.05). Negligible fluorescence was detected within hybrid layers when dentin was conditioned with chitosan, even after thermomechanical cycling, as compared with the controls. Reduction in water permeability in chitosan-conditioned dentin, attributed to smear plug retention, also fostered long-term bond stability. Antibacterial testing performed with live/dead staining indicated that the acetic acid-solubilized chitosan possessed antibacterial activities against 3 single-species biofilms: Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis. Taken together, the new chitosan-based extrafibrillar demineralization strategy retains intrafibrillar minerals, reduces endogenous protease-initiated collagen degradation, prevents water permeation within hybrid layers, and kills bacteria on dentin surfaces, which are crucial factors for enhancing resin-dentin bond durability.

Effect of a novel quaternary ammonium silane cavity disinfectant on durability of resin-dentine bond.

OBJECTIVE: The present study examined the effect of a quaternary ammonium silane (QAS) cavity disinfectant on the viability of human dental pulp cells, dentine bond durability and nanoleakage of simplified etch-and-rinse adhesives. METHODS: Etched dentine surface of third molars were randomly divided into two adhesive groups, Adper™ Single Bond 2 and Prime & Bond® NT™. For each adhesive, the teeth were randomly assigned to five cavity disinfectant groups (N=6): Group 1: deionised water (control); Group 2: 2% chlorhexidine (CHX); Group 3: 2% QAS; Group 4: 5% QAS and Group 5: 10% QAS. The cavity disinfectants were applied on etched dentine surfaces for 20s, followed by adhesive application. The bonded teeth were sectioned for bond strength testing at 24h, 6 months and 12 months. Viability of human dental pulpal cells was examined using MTT assay. Bond strength data were analysed using 3-way ANOVA and Tukey test. Interfacial nanoleakage was evaluated after 24h and 12 months and analysed using Kruskal-Wallis test. RESULTS: Significant differences in bond strength were observed for the factors disinfectants (p<0.001) and time (p<0.001); while the factor, adhesive, was not significantly different (p=0.203). The 2% QAS cavity disinfectant preserved bond strength of both adhesives and reduced interfacial nanoleakage after 12 months. Cell viability was the lowest for 2% CHX, followed by 2% QAS and the control. CONCLUSIONS: The 2% QAS cavity disinfectant demonstrated greater cell viability compared to 2% CHX, with no adverse effect on immediate bond strength and preserved bond stability over time. CLINICAL SIGNIFICANCE: Incorporation of 2% quaternary ammonium silane cavity disinfectant in the resin-dentine bonding protocol enhances the success rate of bonded restorations.

Effect of a novel quaternary ammonium silane on dentin protease activities.

OBJECTIVES: Demineralized dentin collagen release C-terminal cross-linked telopeptide (ICTP) and C-terminal peptide (CTX) during degradation. The present study evaluated the effects of dentin pre-treatment with K21, a quaternary ammonium silane (QAS), on matrix metalloproteinase (MMP) and cathepsin K-mediated collagen degradation. METHODS: Dentin beams were demineralized with 10% H3PO4 for 24h. After baseline dry mass measurements, the beams were divided into 5 groups (N=10) according to protease inhibitors. The beams were pre-treated for 2min with 2% chlorhexidine (CHX), 2%, 5% or 10% QAS; no pre-treatment was performed for the control group. The beams were subsequently incubated in calcium- and zinc-containing medium for 3, 7 or 14days, after which changes in dry mass were measured and incubation media were examined for ICTP and CTX release. The MMP-2 and cathepsin K activities in QAS-treated dentin powder were also quantified using ELISA. RESULTS: The two factors (disinfectants and time) had a significant effect on dry mass loss, ICTP and CTX release (p<0.001). The percentage of dry mass loss increased with time and was significantly lower in all experimental groups when compared to the control at 14days (p<0.001). Conversely, the rate of ICTP and CTX release was significantly lower in the experimental groups, compared to the uninhibited control at 7 and 14days (p<0.001). Dentinal MMP-2 and cathepsin K activities were significantly reduced after demineralized dentin was pre-treated with QAS. CONCLUSION: The experimental QAS is a good inhibitor of MMP and cathepsin K activities in demineralized dentin. CLINICAL SIGNIFICANCE: The newly developed antibacterial quaternary ammonium silane increases the resistance of dentin collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The quaternary ammonium silane cavity disinfectant is promising for use as a protease inhibitor to improve durability of resin-dentin bonds.

[Investigation of sagittal root position in relation to the anterior maxillary alveolar bone: a cone-beam CT study in 300 cases with normal occlusion].

Objective: To investigate the sagittal root position and apical bone height of the maxillary anterior teeth in order to provide anatomical information for immediate implant placement in the esthetic region. Methods: Cone-beam CT (CBCT) data from 300 randomly selected patients who met the inclusion criteria were included in this study. After three-dimensional reconstruction, the sagittal plane (the sagittal plane through the long axis of the tooth) was determined. The positions and angulations of the tooth roots were classified with reference to the alveolar process. By comparing the buccal and palatal bone thickness at the mid-root level, the toot positions with reference to the mid-alveolar line were defined and classified as follows, type B (closer to the buccal alveolar surface), type M (midway between the buccal and palatal alveolar surface) and type P (closer to the palatal alveolar surface). By comparing the angulations of the alveolar process with the long axis of the roots, the angulations were classified as follows, type 1 (root apex angulated toward the palatal side or parallel to the alveolus), type 2 (root apex angulated toward the buccal side with the long axis passing posterior to point A) and type 3 (root apex angulated toward the buccal side with the long axis passing anterior to point A). The frequency of each category was counted and the apical bone height was measured. The subjects were divided into three age groups, 19-30 years, 31-50 years and 51-75 years. Results: The overall mean apical bone height of the healthy maxillary central incisors was (9.2±3.0) mm, the lateral incisors was (10.0±2.9) mm and the canine was (8.1±3.1) mm. There was no significant difference in the height of apical bone between central incisors and lateral incisors (P>0.05). There was no significant difference in the height of apical bone between male and female (P>0.05). The height of apical bone in group 31-50 years and 51-75 years were greater than that in group 19-30 years (P<0.05), respectively. The proportion of the maxillary anterior teeth type B, M, P was 98.5% (1 774/1 800), 0.3% (5/1 800) and 1.2% (21/1 800) respectively. The proportion of type 1, 2, 3 was 2.6% (46/1 800), 58.6% (1 055/1 800) and 38.8% (699/1 800) respectively. Conclusions: There was enough apical bone height in the area of maxillary anterior teeth, but the majority of roots positioned more buccally.

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.