Celastrol inhibits angiogenesis and the biological processes of MDA-MB-231 cells via the DEGS1/S1P signaling pathway.

Celastrol (Cel) shows potent antitumor activity in various experimental models. This study examined the relationship between Cel's antivascular and antitumor effects and sphingolipids. CCK-8 assay, transwell assay, Matrigel, PCR-array/RT-PCR/western blotting/immunohistochemistry assay, ELISA and HE staining were used to detect cell proliferation, migration and invasion, adhesion and angiogenesis, mRNA and protein expression, S1P production and tumor morphology. The results showed that Cel could inhibit proliferation, migration or invasion, adhesion and angiogenesis of human umbilical vein endothelial cells (HUVECs) and MDA-MB-231 cells by downregulating the expression of degenerative spermatocyte homolog 1 (DEGS1). Transfection experiments showed that downregulation of DEGS1 inhibited the above processes and sphingosine-1-phosphate (S1P) production of HUVECs and MDA-MB-231 cells, while upregulation of DEGS1 had the opposite effects. Coculture experiments showed that HUVECs could promote proliferation, migration and invasion of MDA-MB-231 cells through S1P/sphingosine-1-phosphate receptor (S1PR) signaling pathway, while Cel inhibited these processes in MDA-MB-231 cells induced by HUVECs. Animal experiments showed that Cel could inhibit tumor growth in nude mice. Western blotting, immunohistochemistry and ELISA assay showed that Cel downregulated the expression of DEGS1, CD146, S1PR1-3 and S1P production. These data confirm that DEGS1/S1P signaling pathway may be related to the antivascular and antitumor effects of cel.

Huoxue Tongluo decoction combined with acupuncture in the treatment of lumbar disc herniation and its effect on JOA and VAS scores.

BACKGROUND: Lumbar disc herniation (LDH) is a common clinical disease of the skeletal system, and its prevalence has been on a rise. OBJECTIVE: To evaluate the efficacy of Huoxue Tongluo decoction plus acupuncture in the treatment of lumbar disc herniation and its effectiveness in improving the functional recovery of the patients' affected joints and mitigating their pain. METHODS: In this prospective study, 110 patients with lumbar disc herniation enrolled in our Hospital from June 2019 to June 2021 were collected and randomized to receive either conventional treatment (control group) or Huoxue Tongluo Decoction plus acupuncture (study group). RESULTS: Huoxue Tongluo Decoction plus acupuncture resulted in more rapid mitigation of lower extremity symptoms and lumbar symptoms versus conventional treatment (P< 0.05). Patients receiving traditional Chinese medicine (TCM) showed milder inflammatory responses than those with conventional medication, as evidenced by the lower serum concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and high-sensitivity C-reactive protein (hs-CRP) (P< 0.05). After treatment, the study group had higher Japanese Orthopedic Association (JOA) scores and lower visual analogue scale (VAS) scores than the control group (P< 0.05), suggesting that the combination of the herbal decoction and acupuncture provided better functional recovery of the affected joints and pain mitigation for the patients. Furthermore, the lower Pittsburgh sleep quality index (PSQI) scores in patients in the study group indicated better sleep quality of patients after TCM intervention than after conventional treatment (P< 0.05). Huoxue Tongluo Decoction plus acupuncture was associated with a significantly higher efficacy (94.55%) versus conventional treatment (80%) (P< 0.05). CONCLUSIONS: Huoxue Tongluo Decoction combined with acupuncture significantly offers a viable treatment alternative for lumbar disc herniation with promising treatment outcomes, mitigates patients' limb pain, and improves their lumbar function and sleep quality. Further trials are, however, required prior to general application in clinical practice.

The cross-linking and protective effect of artemisinin and its derivatives on collagen fibers of demineralized dentin surface.

OBJECTIVE: To investigate the cross-linking and protective effect of artemisinin (ART), dihydroartemisinin (DHA), and artesunate (AST) on collagen fibers of demineralized dentin surface. METHODS: Molecular docking was used to predict potential interactions of ART, DHA, and AST with dentin type I collagen. Human third molars without caries were completely demineralized and treated with different solutions for 1 min. The molecular interactions and cross-linking degree of ART and its derivatives with dentin collagen were evaluated by FTIR spectroscopy, total extractable protein content, and a ninhydrin assay. Scanning electron microscopy, hydroxyproline release, and ultimate microtensile strength tests (µUTS) were employed to confirm the mechanical properties and anti-collagenase degradation properties of dentin collagen fibers. RESULTS: ART, DHA, and AST combined with dentin type I collagen mainly through hydrogen bonding and hydrophobic interactions, and the cross-linking reaction sites were mainly C=O and CN functional groups. Compared to the control group, ART and its derivatives significantly increased the degree of cross-linking. Additionally, significant increases were observed in resistance to enzymatic digestion and mechanical properties of the artemisinin and its derivatives group. CONCLUSION: ART, DHA, and AST could cross-link with demineralized dentin collagen, through improving the mechanical properties and anti-collagenase degradation properties. CLINICAL SIGNIFICANCE: The study endorses the potential use of ART and its derivatives as a prospective collagen cross-linking agent for degradation-resistant and long-period dentin bonding in composite resin restorations.

Scoring consistency of standard patients and examiners in the developed dental objective structured clinical examination system.

OBJECTIVE: To investigate the role of standard patients (SPs) and examiners as assessors for scoring in the dental objective structured clinical examination (OSCE) system and to evaluate the scoring differences between them. METHODS: We developed the doctor-patient communication and clinical examination station in the OSCE system. The examination time of this station was 10 min, and the examination institution wrote the script and recruited SPs. A total of 146 examinees who received standardized resident training at the Nanjing Stomatological Hospital, Medical School of Nanjing University between 2018 and 2021 were assessed. They were scored by SPs and examiners according to the same scoring rubrics. Subsequently, the SPSS software was used to analyze the examination results of different assessors and evaluate the consistency. RESULTS: The average score of all examinees provided by SPs and examiners was 90.45 ± 3.52 and 91.53 ± 4.13, respectively. The consistency analysis showed that the intraclass correlation coefficient was 0.718, which was indicative of medium consistency. CONCLUSION: Our findings showed that SPs could be used directly as assessors, as they could provide a simulated and realistic clinical setting and create favorable conditions for comprehensive competence training and improvement for medical students.

Antibacterial one-step self-etching dental adhesive with silver nanoparticles synthesized in situ.

OBJECTIVES: The objective of this study is to value the long-term antibacterial capability and adhesive properties of one-step self-etching dental adhesive containing silver nanoparticles (AgNPs) synthesized in situ. METHODS: One-step self-etching adhesives with various weight percentages of silver 2-ethylhezanoate (0%, 0.05%, 0.10%, and 0.20%) were obtained by in-situ synthesis; the sizes and distribution of the AgNPs in resin were observed. The antibacterial effects of dentin-resin specimens were assessed by various test methods after being aged for 1 week to 1 year. The microtensile bond strength (µTBS) and interfacial nanoleakage (NL) were evaluated using extracted human teeth after being aged for 1 day and 1 year. RESULTS: Uniform distribution of AgNPs in resin was observed in all experimental groups, and the average size was 4.71 nm-4.81 nm. All groups containing AgNPs showed significant antibacterial differences from the control group (P<0.05) over the ageing of 1 year. Although the increase of concentration tended to improve antibacterial activity, significant differences were not observed between the 0.10% and 0.20% groups (P>0.05). No significant differences were observed between all experimental groups and the control group in µTBS testing and NL testing at 1-day and 1-year time points (P>0.05). CONCLUSIONS: 0.10% AgNPs synthesized in situ might be appropriate to impart a long-term antibacterial ability to the one-step self-etching adhesive, without affecting its adhesive performance. CLINICAL SIGNIFICANCE: This study suggests that in-situ synthesis of AgNPs is an effective method to improve the antibacterial ability of dental adhesives with the potential to inhibit secondary caries.

In situ immobilization of silver nanocrystals in carbon nanoparticles for intracellular fluorescence imaging and hydroxyl radicals detection.

Silver nanoparticles (Ag NPs) have attracted extensive research interest in bioimaging and biosensing due to their unique surface plasmon resonance. However, the potential aggregation and security anxiety of Ag NPs hinder their further application in biomedical field due to their high surface energy and the possible ionization. Here, binary heterogeneous nanocomplexes constructed from silver nanoparticles and carbon nanomaterials (termed as C-Ag NPs) were reported. The C-Ag NPs with multiple yolk structure were synthesized via a one-step solvothermal route using toluene as carbon precursor and dispersant. The hydrophilic functional groups on the carbon layer endowed the C-Ag NPs excellent chemical stability and water-dispersity. Results showed that C-Ag NPs demonstrated excellent safety profile and excellent biocompatibility, which could be used as an intracellular imaging agent. Moreover, the C-Ag NPs responded specifically to hydroxyl radicals and were expected to serve as a flexible sensor to efficiently detect diseases related to the expression of hydroxyl radicals in the future.

Simultaneous Determination of Amphenicols and Metabolites in Animal-Derived Foods Using Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Amphenicols are widely used to prevent and treat animal diseases. However, amphenicol residues accumulate in livestock and poultry and harm consumers. We hypothesized that one can combine solid-phase extraction (SPE) with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to simultaneously determine amphenicols and metabolites in pork, beef, lamb, chicken, and their products and meet government regulations for maximum residue limits. We extracted crude samples with ethyl acetate and ammonia water (98:2, v/v), purified the samples with a CNW Si SPE column, defatted the samples with acetonitrile-saturated n-hexane, and then determined the resulting analytes by UHPLC-MS/MS. The limit of detection of the analytes in livestock and poultry meat was 0.03-1.50 µg/kg, and the limit of quantification was 0.05-5.00 µg/kg. Measured chloramphenicol, thiamphenicol, and florfenicol concentrations were linear over the range 0.50-50 µg/kg; and the florfenicol amine concentration was linear over the range 5.00-200 µg/kg (all with correlation coefficients >0.9990). The recovery of the spiked samples was between 72% and 120%. The intraday relative standard deviation (RSD) ranged from 1% to 9%, and the interday RSD ranged from 1% to 12%. Based on the above results, the current method is sensitive, accurate, and reproducible with the detection limits being well below the maximum residue limits as per Chinese standard GB 31650-2019, and thus, our research hypothesis could be confirmed.

Moxibustion for primary dysmenorrhea: A protocol for evidence-based clinical practice guideline.

BACKGROUND: Primary dysmenorrhea (PD) is a common gynecological disease characterized by lower abdominal pain. Moxibustion as a traditional Chinese treatment, can effectively treat PD with few adverse reactions. Nowadays, there is still no standard guideline for moxibustion treatment of PD, so related clinical practice guidelines need to be developed. METHODS: This guideline will be developed in line with the latest guideline definition from Institute of Medicine, and that applies the GRADE system as well as the World Health Organization handbook to appraise the quality of evidence and develop recommendations. We will set up a Guideline working group, put forward the corresponding problems based on the principle of Population, Intervention, Comparison, Outcomes (PICO), and complete the literature retrieval. After achieving consensus through evidence syntheses and 2 to 3 rounds of Delphi process, we will also consider patients values and preferences and implement peer review in the guideline. RESULT: We will put forward evidence-based best practice recommendations and moxibustion standard to improve the symptoms caused by primary dysmenorrhea in a more efficient way. At present, the research is still in progress, and there is no result to report. CONCLUSIONS: This guideline will be helpful to clinical acupuncturists and other professionals to further improve clinical efficacy in treating PD with moxibustion. Moreover, we will also constantly update and evaluate the evidence to both support recommendations and identify gap areas for future research. SYSTEMATIC REVIEW REGISTRATIONS: registration number: IPGRP-2020CN021.

Magnetic-induced graphene quantum dots for imaging-guided photothermal therapy in the second near-infrared window.

Graphene quantum dots (GQDs) are considered emerging nanomaterials for photothermal therapy (PTT) of cancer due to their good biocompatibility and rapid excretion. However, the optical absorbance of GQDs in shorter wavelengths (<1000 nm) limits their overall therapeutic efficacies as photothermal agent in the second near infrared window (1000-1700 nm, NIR-II). Herein, we report a type of GQDs with strong absorption (1070 nm) in NIR-II region that was synthesized via a one-step solvothermal treatment using phenol as single precursor by tuning the decomposition of hydrogen peroxide under a high magnetic field with an intensity of 9T. The obtained 9T-GQDs demonstrate uniform size distribution (3.6 nm), and tunable fluorescence (quantum yield, 16.67%) and high photothermal conversion efficacy (33.45%). In vitro and in vivo results indicate that 9T-GQDs could efficiently ablate tumor cells and inhibit the tumor growth under NIR-II irradiation. Moreover, the 9T-GQDs exhibited enhanced NIR imaging of tumor in living mice, suggesting the great probability of using 9T-GQDs for in vivo NIR imaging-guided PTT in the NIR-II window.

Synthesis and biomedical applications of graphitic carbon nitride quantum dots.

Graphitic carbon nitride quantum dots (g-CNQDs) have attracted much attention for biomedical applications by virtue of their good biocompatibility, stable fluorescence, high quantum yield, and nontoxicity. On the basis of understanding the intrinsic properties and structural features in the intriguing system, enormous efforts have been devoted to optimizing synthetic methods and structures of g-CNQDs. A vast number of studies have also been pursued to discuss the potential applications of g-CNQDs in biomedical areas for biosensing, bioimaging, drug delivery and theranostics. In this review, we summarize the recent advances and applications and address the future challenges and opportunities of these g-CNQDs in the biomedical field.

[Influence of the dentin smear layer trait on the bond strength of the self-adhesive resin cements].

OBJECTIVE: This work aimed to evaluate the influence of smear layer on the bonding effectiveness and durability of the self-adhesive resin cements to dentin. METHODS: A total of 48 fresh caries-free third molars with exposed dentin surface were divided into two groups. The dentin surfaces were treated using a standard grit diamond bur (group A) or further polished using a fine grit diamond bur (group B) and then bonded with either of the two self-adhesive resin cements, namely, Clearfil SA Cement (CSA, Kuraray) and Multilink Speed (MS, Ivoclar Vivadent). After 24 h or 2-year water storage, a microtensile bond strength test was performed. RESULTS: In group A, the dentin surface was rough, the smear layer was thick, and the dentin tubule orifice detritus showed low embolism value. In group B, the dentin surface roughness decreased, the embolism proportion increased, and the smear layer became thin. The initial bonding strengths of CSA and MS in group A were significantly lower than those in group B (P<0.05). The bonding strengths of CSA and MS significantly decreased after two years of water storage (P<0.05). For CSA, the bond strength of group B was significantly lower than that of group A (P<0.05). For MS, the differences in the bonding strength between groups A and B were insignificant (P>0.05). CONCLUSIONS: The properties of the smear layer and the types of self-adhesive resin cement used affected the bond strength and durability.

Application of OSCE for Stage Assessment in Standardized Training for Oral Residents.

The aim of this study was to establish and implement an objective structured clinical examination (OSCE) for stage assessment in standardized training for oral residents, evaluating its validity and suitability. An OSCE was established for stage assessment of 158 residents in a program in Jiangsu Province, China. Its validity and suitability were evaluated using indices such as reliability and discrimination coefficients of assessment results. The established OSCE had eight stations: interpretation of auxiliary examination results, basic knowledge, doctor-patient communication and clinical examination, clinical case analysis, medical record and prescription writing, public skills, first aid skills, and specialist's operation skills. The mean overall score and consistency coefficient (Cronbach's alpha) for the test subjects were 83.64±3.69 points and 0.732, respectively. The developed OSCE was reasonably established, with credible assessment results, and indices such as mean and discrimination coefficient of test scores from each station were appropriate. Therefore, the proposed protocol was found to be reliable and suitable.

NIR-responsive carbon-based nanocarriers for switchable on/off drug release and synergistic cancer therapy.

Herein, we present a light-switchable drug delivery system based on chitosan-gated carbon-based nanocarriers (CGC NCs) that exhibit a loading capacity for doxorubicin as high as ∼89.65 wt% and controlled on/off release with/without NIR irradiation. In vitro and in vivo results show that the CGC NCs manifest high efficacy for cancer therapy through a synergistic effect of combined chemo-photothermal treatment.

[An exploration on computerized examination system of dental objective structured clinical examination].

PURPOSE：In view of the present problems of clinical skill examination, in order to evaluate the candidate's clinical ability comprehensively and objectively, we constructed and implemented dental objective structured clinical examination system mainly based on computer. METHODS：This system was a multi-station examination which had 3 parts and 8 sites. The stations were composed of a variety of testing methods, including choice questions, auxiliary examinations, case analysis and basic operation skill. RESULTS: By using the computerized dental objective structured clinical examination system, we could smoothly test the ability of stomatological students in a relatively short time. The clinical ability, learning ability and professional quality could be evaluated more objectively in many ways. CONCLUSIONS：This system help students adapt to early examination of medical practitioners, improve students' clinical skills, and is worthy of wide application.

Comparing the Effectiveness of Electroacupuncture with Different Grades of Knee Osteoarthritis: A Prospective Study.

BACKGROUND: The electroacupuncture (EA) with different number of points significantly affected its efficacy on knee osteoarthritis (KOA), and the severity of KOA also influenced its response to treatments. Hence, we prospectively compared the clinical efficacy of EA on KOA with different severities. METHODS: A total of 132 KOA patients recruited from 181st Central Hospital of The Chinese People's Liberation Army between March 2014 and March 2015 were classified into 4 KOA stages according to Kellgren Lawrence grading scale. They were allocated into three treatment groups, including two-point group, four-point group and six-point group. Patients in the six-point group received treatment at six-points including ST34, SP10, SP9, ST36, ST35 and EX-LE4. Patients in the four-point group received treatment at ST34, SP10, ST35 and EX-LE5, while patients in the two-point group received treatment at ST35 and EX-LE4. Visual Analog Scale (VAS), McMaster Universities Osteoarthritis Index (WOMAC) and self-assessment questionnaire of patients were assessed after treatment. RESULTS: Three kinds of EA treatments all have significant clinical effects on KOA patients with down-regulated scores of VAS and WOMAC. Regarding post-treatment efficacy, the six point group exhibited lower VAS score and higher WOMAC score compared with the other two groups. For patients with different KOA grades, patients with higher KOA grades were associated with lower grade of treatment efficacy. CONCLUSIONS: Patients with KOA, especially those with lower KOA stages, could gain beneficial efficacies from EA treatments with two, four and six points, respectively.

Role of Rho-mediated ROCK-Semaphorin3A signaling pathway in the pathogenesis of Parkinson's disease in a mouse model.

OBJECTIVE: The present study aims to elucidate the role of Rho-mediated ROCK-Semaphorin3A signaling pathway in the pathogenesis of Parkinson's disease (PD) in a mouse model. METHODS: One-hundred twelve eight-week male C57BL/6 mice were selected. The mouse model of PD was constructed by intraperitoneal injection of MPTP. All mice were divided into four groups (28 mice in each group): Blank group, Model group, Rho knockout (Rho+/-) group and ROCK knockout (ROCK+/-) group. Changes of behavior of the mice were studied through automatic moving test and rotarod test. Immunohistochemistry (IHC) was used to detect the expressions of TH, CD11b and GFAP. High performance liquid chromatograph (HPLC) was performed for detection of dopamine and its metabolic product. The mRNA and protein expressions of Rho, ROCK, Sema3A, PlexinA and NRP-1 were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. RESULTS: Rho and ROCK knockout improved the damage caused by MPTP on the behavior of mice and protected dopaminergic neurons from injury, along with the increases of dopamine and its metabolic product. The mRNA and protein expressions of Rho, ROCK, Sema3A, PlexinA and NRP-1 were increased in PD mice in the Model group compared with those in the Blank group. Compared to the Model group, the mRNA and protein expressions of Rho, ROCK, Sema3A, PlexinA and NRP-1 were reduced in the Rho+/- and ROCK+/- groups. CONCLUSION: These findings indicate that Rho and ROCK knockout may improve the behavior of mice and prevent MPTP-induced dopaminergic neurons damage by regulating Sema3A, PlexinA and NRP-1 in a mouse model of PD.

Cytotoxic Effects of One-step Self-etching Dental Adhesives on Human Periodontal Ligament Fibroblasts In Vitro.

PURPOSE: To evaluate the potential cytotoxic effects of four one-step self-etching dental adhesives [Adper Easy One (AEO), iBond (IB), Clearfil S³ Bond (CSB), and G-Bond (GB)] on cultured human periodontal ligament fibroblasts. MATERIALS AND METHODS: Cured adhesives were immersed in complete DMEM or deionized water and maintained at 37°C for 24 h, followed by sterilization. The deionized water-based extract was used for Fourier transform infrared spectroscopy analysis. The DMEM-based extract was diluted into various concentrations for cytotoxicity tests. The viability, integrity, and apoptosis of cultured human periodontal ligament fibroblasts upon treatment with the extracts were determined using the CCK-8 assay, microscopy, and flow cytometry. RESULTS: All of the four adhesives induced cell viability loss, cell morphology alteration, and cell death. GB showed the greatest cytotoxicity by inducing cell apoptosis and necrosis, while IB had the weakest cytotoxic effect on the cultured cells. CONCLUSION: All tested dental adhesives have significant adverse effects on cell viability. Therefore, precautions should be taken to protect the periodontal tissues when dental adhesives are applied in the clinic.

Influence of biphasic calcium phosphate surfaces coated with Enamel Matrix Derivative on vertical bone growth in an extra-oral rabbit model.

OBJECTIVE: The aim of this study was to investigate the ability of Enamel Matrix Derivative (EMD) on vertical bone regeneration around dental implants placed in an extra-oral rabbit model. MATERIAL AND METHODS: A total of 30 Straumann BL implants were partially embedded in transverse orientation into the posterior mandibles of 15 rabbits. Macro-structuring BiPhasicCaPST (BCPT1), micro-structuring BiPhasicCaPST (BCPT2), and deproteinized bovine bone mineral (DBBM) were placed around the implant and covered with a scaffold stabilizing "umbrella." EMD was incorporated within the scaffold for test sites, but not control sites. Histological analysis was performed on retrieved specimens after 10 weeks of healing to assess new bone formation. RESULTS: All treatment groups displayed new supracrestal bone formation as determined by histomorphometric measurements, with mean values of new bone height ranging between 0.62 and 1.13 mm. Histological analysis revealed a higher mean bone formation (%) around the test sites where EMD (34.7, 95%CI: 27.1-39.4) was released from the scaffold, whereas the control group without EMD release (26.4, 95%CI: 16.3-31.9) (P = 0.069). The mean fBIC (%) in the BCPT2 group increased by the addition of EMD relative to no EMD (67.2, 95%CI: 48.6-84.1) and (54.7, 95%CI: 32.3-68.9), respectively). The BCPT2/EMD and DBBM/EMD interventions showed the greatest mean bone density (BA/TA), respectively, (12.8, 95%CI: 8.9-36.5) and (11.2, 6.3-16.4) in ROI 1. Values in ROI 2 were, similarly, (24.9, 95%CI: 17.2-31.7) and (27.7, 19.2-35.3). BA/TA in ROI 2 differences between the BCPT2 groups with and without EMD was statistically significant (P = 0.026), as well as the DBBM groups with and without EMD (P = 0.038). CONCLUSIONS: A layer of new bone was formed in both test and controls. The release of EMD from BCPT2 and DBBM adjacent to a bone-level implant with an SLActive surface and scaffold retention umbrella consistently regenerated the greater fBIC and bone density along the length of the implant.

[Effect of a chemical primer on the bond strength of a zirconia ceramic with self-adhesive resin cement].

OBJECTIVE: To evaluate the bond strength and durability of a self-adhesive resin cement with a zirconia ceramic pretreated by a zirconia primer. METHODS: Zirconia ceramic (Vita Inceram YZ) plates with a thickness of 2.5 mm were fired, polished, and then cleaned. Half of the polished ceramic plates were sandblasted with 50 µm alumina particles at 0.3 MPa for 20 s. The surface compound weight ratios were measured via X-ray fluorescence microscopy. The polished and sandblasted ceramic plates were directly bonded with self-adhesive resin cement (Biscem) or were pretreated by a zirconia primer (Z Primer Plus) before bonding with Biscem. The specimens of each test group were divided into two subgroups (n=10) and subjected to the shear test after 0 and 10,000 thermal cycles. The data were analyzed via three-way ANOVA. RESULTS: After air abrasion, 8.27% weight ratio of alumina attached to the zirconia surface. Compared with air abrasion, primer treatment more significantly improved the primary resin bond strength of the zirconia ceramic. The primary resin bond strength of the zirconia ceramic with no primer treatment was not affected by thermocycling (P>0.05). However, the primary resin bond strength of the zirconia ceramic with primer treatment was significantly decreased by thermocycling (P<0.05). CONCLUSION: Primer treatment can improve the primary resin bond strengths of zirconia ceramics. However, the bond interface of the primer is not stable and rapidly degraded during thermocycling.

[Influence of light irradiation mode on microhardness of dual cured resin cements].

PURPOSE: To investigate the influence of different light irradiation modes on microhardness of dual-curing resin cements. METHODS: The cylindrical specimens (1 mm in thickness and 7.5 mm in diameter) of 5 self-adhesive resin cements (Biscem, Clearfil SA Cement, G-CEM LinkAce, Maxcem Elite and RelyX U100) and 2 universal resin cements(DUOLINK and Nexus 3) were irradiated respectively by a continuous mode (light-curing for 20 s) and a delayed mode (light-curing 5 s + auto-curing 60 s + light-curing 20 s), and then they were placed dry in a light-proof thermostat at 37 degrees centigrade. Surface microhardness of specimen was detected at 0.5, 24 h and 4 weeks post-irradiation. After that period of time, all specimens were soaked in ethanol for 24 h, their hardness were detected again, and the percentage of hardness reduction after soaking were calculated. Data were analyzed by SPSS 16.0 software package. RESULTS: The hardness of all resin cements under both irradiation modes increased mainly within 24 h post-irradiation. The irradiation mode did not affect the hardness of all resin cements 4 weeks after irradiation significantly (P>0.05), except for Biscem. However, after ethanol softening, 5 self-adhesive resin cements cured by the continuous mode had higher hardness reduction percentage than that cured by delayed mode (P<0.05); while hardness reduction percentage of 2 universal resin cements had no significant difference between continuous and delayed cure modes (P>0.05). CONCLUSIONS: The self-adhesive resin cements cured by delayed mode had better anti-softening ability. Supported by Nanjing Medical Science and Technology Development Fund (ZKX09035), Nanjing Science and Technology Development Fund (201001083) and Nanjing Medical Science and Technology Development Fund (YKK10125).