Shear-bond strength of different Self-Etching adhesive systems to dentin with or without laser irradiation before photopolymerization (A comparative Study)

This study aimed at comparing shear-bond strength (SBS) of different self-etching adhesive systems (Clearfil S³ Bond Plus, G-Premio BOND and IBond) to dentin without or with diode-laser irradiation before photo-polymerization and to determine the effect of storage and thermo-cycling on SBS of adhesive systems. Methods: The buccal surface of 84 extracted maxillary premolars was grounded to create flat surface. The specimens were allocated into 3 groups (n = 28) depending upon the adhesive systems, then each group was divided into two sub-group (I, II) (n = 14). After the placement of respective adhesive systems on the flat surface, adhesive system in group I was photo-polymerized immediately, while in group II, the adhesive systems were exposed to diode-laser before photo-polymerization. Composite cylinder (4 mm in diameter and 2 mm height) was built on the flat surface of each specimen. Then group I and II were divided into two sub-groups (n = 7) according to the storage time and thermo-cycling (1 day without thermo-cycling or 72 days with thermo-cycling) then all the specimens were stored in distilled water. The SBS was measured at the end of storage period. ANOVA, Duncan’s Multiple Range Test and independent t-test “P ≤ 0.05” were used for data analysis. Results: G-premio BOND showed the highest mean value of SBS followed by Clearfil S³ Bond plus without significant difference between them, while IBond revealed the least mean value. Laser irradiation had positive effect on the bond-strength of all tested adhesive systems. The results also showed that the storage with thermo-cycling had negative effect on the bond-strength in groups without laser irradiation for all tested adhesive systems, while for groups with laser irradiation, the reduction in the bond-strength of all tested adhesive systems was not significant. Conclusion: Diode-laser application prior to photo-polymerization of self-etch adhesive systems significantly increased the bond-strength to dentin and can increase the durability of composite adhesion.     

超声引导下辅助诊断和治疗冻结肩的研究进展

冻结肩是常见的肩部疾病,传统非可视化治疗冻结肩效果欠佳。近年来,超声引导具有动态实时定位、无辐射、便携性、低成本等优点在辅助诊断和治疗冻结肩患者中得到成功应用,不仅能提供精确的诊断,也提高了患者中长期的疗效。本文就超声引导辅助诊断和治疗冻结肩的研究进展进行综述。     

针刀联合拔罐治疗肩周炎60例

目的:观察小针刀联合拔罐疗法治疗肩周炎的临床疗效。方法:将2017年12月-2018年12月就诊于我院治未病中心的60例肩周炎患者随机分为治疗组30例,对照组30例,治疗组采用针刀联合拔罐,对照组采用普通针刺联合拔罐,两组治疗周期均为15 d,观察两组治疗前后临床总有效率和不良反应发生率。结果:两组经过15 d天治疗后,不良反应发生率相当,但治疗组总有效率明显高于对照组。结论:基于中医循经辨证取穴与西医病因病理及解剖定位相结合提高了针刀治疗肩周炎的治愈率。     

Effect of the photoinitiator system on the polymerization of secondary methacrylamides of systematically varied structure for dental adhesive applications

ObjectiveThe aim of this study was to investigate the influence of the photoinitiator system on the polymerization kinetics of methacrylamide-based monomers as alternatives to methacrylates in adhesives dental-based materials.MethodsIn total, 16 groups were tested. Monofunctional monomers (2-hydroxyethyl methacrylate) – HEMA; (2-hydroxy-1-ethyl methacrylate) −2EMATE, (2-hydroxyethyl methacrylamide) – HEMAM; and (N-(1-hydroxybutan-2-yl) methacrylamide) −2EM; were combined with bifunctional monomers containing the same polymerizing moieties as the monofunctional counterparts (HEMA-BDI; 2EMATE-BDI; HEMAM-BDI; and 2EM-BDI) at 50/50 M ratios. BHT was used as inhibitor (0.1 wt%) and the photoinitiators used were: CQ + EDMAB (0.2/0.8), BAPO (0.2), IVOCERIN (0.2), and DMPA (0.2), in wt%. The polymerization kinetics were monitored using Near-IR spectroscopy (∼6165 cm⁻¹) in real-time while the specimens were photoactivated with a mercury arc lamp (Acticure 2; 320−500 nm, 300 mW/cm²) for 5 min, and maximum rate of polymerization (Rp_max, in %.sˉ̄¹), degree of conversion at Rp_max (DC@Rp_max, in %), and the final degree of conversion (Final DC, in %) were calculated (n = 3). Initial viscosity was measured with an oscillating rheometer (n = 3). Data were analyzed using Two-way ANOVA for the polymerization kinetics and one–way ANOVA for the viscosity. Multiple comparisons were made using the Tukey’s test (∝ = 0.05).ResultsThere was statistically significant interaction between monomer and photoinitiator (p < 0.001). For the methacrylates groups, the highest Rp_max was observed for HEMA + DMPA and 2EMATE + BAPO. For methacrylamides groups, the highest Rp_max were observed for HEMAM and 2EM, both with DMPA. Final DC was higher for the methacrylate groups, in comparison with methacrylamide groups, independent of the photoinitiators. However, for the methacrylamide groups, the association with BAPO led to the lowest values of DC. In terms of DC@Rp_max, methacrylate-based systems showed significantly higher values than methacrylamide formulations. DMPA and Ivocerin led to higher values than CQ/EDMAB and BAPO in methacrylamide-based compounds. BAPO systems showed de lowest values for both HEMA and HEMAM formulations. For the viscosity (Pa.s), only 2EM had higher values (1.60 ± 0.15) in comparison with all monomers. In conclusion, polymerization kinetics was affected by the photoinitiators for both monomers. Viscosity was significantly increased with the use of secondary methacrylamide.Significancethis work demonstrated the feasibility of using newly-synthesized methacrylamide monomers in conjunction with a series of initiator systems already used in commercial materials.     

Evaporating solvents with a warm air-stream: effects on adhesive layer properties and resin-dentin bond strengths

OBJECTIVES: This study evaluated the effect of a warm or cold air-dry stream for solvent evaporation on the microtensile resin-dentin bond strength (muTBS), nanoleakage pattern (SEM), degree of conversion (DC) and solvent evaporation rates (SE) of an ethanol/water- (Adper Single Bond, [SB] 3MESPE) and an acetone-based (Prime & Bond 2.1, [PB] Dentsply), two-step etch-and-rinse adhesive system. MATERIALS AND METHODS: Adhesives were applied on demineralized dentin surfaces. For SE, a warm or cold air-dry stream (10 s) was applied prior to light-activation (10 s). Bonded sticks (0.8mm2) were tested in tension (0.5 mm/min). Two bonded sticks from each tooth were immersed in a 50% (w/v) solution of silver nitrate (24 h), photodeveloped (8 h) and analyzed by SEM. The DC and solvent evaporation rate of the adhesives were evaluated under FTIR and analytical balance, respectively. Data were analyzed by two-way ANOVA and Tukey test (alpha=0.05). RESULTS: Higher muTBS and lower nanoleakage were observed when the SE step was performed with warm air-dry stream. However, the DC of the adhesives was not altered by the use of a warm air-dry. CONCLUSIONS: The use of a warm air-dry stream seems to be a clinical tool to improve the bond strength and the quality of the hybrid layer (less nanoleakage infiltration), since it might reduce the number of pores within the adhesive layer.     

One-year clinical evaluation of a flowable resin liner associated with a microhybrid resin in noncarious cervical lesions

The aim of this study was to compare the clinical performance over 1 year of a microhybrid composite resin for class V restorations both lined and not lined with a flowable composite resin. Nineteen patients having at least two pairs of cervical noncarious lesions under occlusion were enrolled in this study. A total of 38 restorations were placed, half for each group (Single-Bond + Filtek-Flow + Filtek Z250, and Single-Bond + Filtek Z250). Two calibrated operators placed all restorations according to the manufacturers instructions. Two other independent examiners evaluated the restorations at baseline and after a 12-month period according to the USPHS criteria and modified criteria for color match. The classic alpha score was divided into A1 for not detectable and A2 for slightly discernible filling. Statistical analysis was conducted using Fishers exact test and McNemars test (P=0.05). One restoration was lost after 12 months for each group (retention rate 95% for each group). After 12 months, 18 restorations showed a trend towards dark yellowing (color match A2). The use of Filtek Flow as a liner under Filtek Z250 restorations did not improve the clinical performance of class V restorations after 6 and 12 months of evaluation.     

氟离子缓释正畸粘接剂缓释性能的研究

目的全面了解树脂型氟离子缓释正畸粘接剂(fluoride releasing adhesive，FRA)缓释氟离子的性能，建立一套评价FRA氟离子缓释性能的测试方法及指标。方法测定并计算FRA在一定时间中累计氟离子释放量，绘制出时间—氟离子累计释放量趋势线，并计算每单位质量FRA有效氟离子释放量。结果时间—氟离子累计释放量趋势线显示，FRA在90d内能持续、稳定地释放氟离子，每单位质量FRA在90d内有效氟离子释放量为449μg/g。结论本实验FRA试样具有稳定缓释氟离子的能力。