目的:评估不同预备方式对前牙瓷贴面修复临床应用效果的影响.方法:对42例患者,共计131颗变色前牙进行瓷贴面修复的患者进行临床评估.患牙分别进行了超薄不备牙(A组,n=16)、超薄备牙(B组,n=53)、传统备牙(C组,n=62)3种不同方式的贴面修复,患者随访1年.采用改良的加利福尼亚牙科协会-瑞格(CDA/Ryge)标准对修复体进行评估,同时观察牙周状况及术后敏感等情况.结果:修复后1年的随访观察中,A组各项指标均优于B组和C组(P＜0.05).A、B、C组修复体的脱落分别为7、0和0例(P＜0.05).术后敏感在A、B、C组为0、3和11例(P=0.055),继发龋为0,1和2例(P=1.00).结论:微创的患牙预备方法进行前牙瓷贴面修复可获得更好的修复效果.

目的 评价在线选色训练系统在口腔医学专业本科生牙科色彩学与比色教学中的应用效果.方法 在口腔修复专业课《色彩学与比色》教学中,对我院五年制口腔医学专业2016级及2017级学生分别采用常规理论教学和常规理论教学加在线选色训练的方式进行授课.课程结束后,利用在线选色训练系统测试和比色板测试两种方式对本科生的比色技能进行评价和比较.结合调查问卷,对两组的教学效果进行评价.结果 观察组的比色正确学生数显著多于对照组,测试耗时显著短于对照组,比色成绩显著高于对照组(P<0.05).观察组的色彩学基本理论知识和Vita 3D-Master比色板使用方法知识点得分高于对照组(P<0.05).观察组对色彩学理论知识和比色板使用知识的掌握程度优于对照组(P<0.05).观察组对色彩学教学的满意度显著高于对照组(P<0.05).结论 常规理论授课加在线选色训练应用在《色彩学与比色》教学中,可有效改善学生对相关知识的掌握程度,并提高比色技能.

目的:通过T-scanⅢ对咬合力的控制和龈沟液中RANKL、OPG水平的变化及牙槽骨高度的测量评价牙周炎患者固定义齿的修复效果.方法:选择14例前牙缺失并需要固定义齿修复,但至少有一颗或多颗牙基牙牙槽骨吸收≥1/2而≤2/3的患者为受试对象,且将符合牙槽骨吸收≥1/2而≤2/3的基牙作为目标基牙,共20颗.患者经过彻底的牙周治疗并将牙槽骨吸收严重的牙进行去髓术后,行前牙固定义齿修复,并在戴牙时用T-scanⅢ辅助调牙合.并于修复前、修复后即时和修复后1个月、3个月检查咬合力心的位置、检测目标基牙龈沟液中RANKL、OPG水平的变化及目标基牙牙槽骨高度的变化.结果:患者在正中咬合时,COF距X轴的垂直距离在戴牙后即时和修复后与修复前相比显著性降低(P<0.05);目标基牙OPG的浓度在修复后比修复前升高(P<0.05),且随时间的延长而升高;目标基牙RANKL/OPG比值在修复后比修复前降低(P<0.05),且随时间延长而降低.目标基牙牙槽骨高度在任何两个时间点都没有统计学差异(P>0.05),即随时间变化牙槽骨高度变化不明显.结论:牙槽骨吸收大于1/2而小于2/3的牙经完善牙周治疗并行去髓术后作为基牙进行固定义齿修复,在短期内其临床各指标均保持稳定,长期疗效有待进一步观察.

Commercially available dental adhesives fail to chemically unite the demineralized collagen matrix with resinous materials within the resin-dentin interface. Sub-micron separations between the collagen fibrils and polymerized resin provide the backdrop for bond deterioration. Here, novel isocyanate-terminated urethane methacrylate precursors (UMP) were synthesized with the capacity to bond chemically to dentin collagen via covalent and hydrogen bonds. Collagen grafted with UMP also copolymerized with other methacrylate resin monomers, thereby producing a monoblock of chemically-linked biocomposite. The viscosity, degree of conversion and biocompatibility of UMP are comparable with commercially available resin monomers. An experimental adhesive containing 40% UMP demonstrated co-polymerization capability, good infiltration capacity and achieved higher immediate bond strength to dentin than the control commercially available adhesive. Improvement of dentin bonding by incorporation of UMP into dentin adhesives justifies future evaluation of the potential of these UMP-based adhesives in extending the longevity of resin-dentin bonds. Statement of Significance Composite-adhesive restorations have become an indispensable treatment modality in contemporary restorative dentistry. While the inability of these adhesives to bond chemically with collagen undermines the bond quality. This study describes a novel isocyanate-terminated urethane multi methacrylate precursors (UMP) which can bridge dentinal matrix collagen with adhesive resin by covalent and hydrogen bonds. Furthermore, an experimental UMP-based adhesive shows better co-polymerization capability, good infiltration capacity and higher immediate bond strength than the putatively effective adhesive Single Bond 2. The new chemical bonding mechanism based on UMP would theoretically produce more stable bonding interface that are more resistant to degradation. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd.

The problems in contemporary Prosthodontic education were analyzed by comparison of the results between programme end test and practicing dentist simulation test.According to the results,the contents that including the professional knowledge in the 2 tests are almost the same.There are significant differences in the method and style of the 2 tests.The results of the two tests are significantly different in the pass rate,excellent rate and types of errors.It is of great important to reform the contemporary Prosthodontic educationin of the teaching purpose,content and test methods.

探讨高压气体吹拂一步法自酸蚀粘接系统S3 bond对树脂牙本质粘接界面纳米渗漏的影响.5颗离体的完整无龋第三磨牙“十”字纵切,取其中的18份随机分为3组(轻吹;强吹;强吹+轻吹.轻吹气压为0.1 MPa,强吹气压为0.3 MPa),每组6份牙体组织,去除冠釉,进行粘接.各组粘接完成后,37℃水浴24 h,每份牙体组织切出2片薄片状试件,制备纳米渗漏试件,分别使用场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)观察粘接界面纳米渗漏(n=6).FESEM和TEM观察显示,轻吹组的纳米渗漏最多;强吹组次之;强吹+轻吹组的纳米渗漏最少.轻吹组与强吹+轻吹组纳米渗漏结果之间的差异具有统计学意义(P＜0.05).涂布2层S3 bond自酸蚀粘接剂,第1层强吹、第2层轻吹可显著减少粘接界面纳米渗漏,提高粘接界面封闭性.

临床消化病学教学是培养研究生科研思维和临床技能的重要平台.面对消化病学新技术和新方法的出现,以及培养创新型研究生的要求,必须创新理念,改革探索和构建适应时代发展的教学体系,并依据教学计划在教师指导下顺利完成学习内容,实现提高研究生综合运用消化病学基本理论和技能的水平,熟悉或掌握消化病学相关基本技术应用,全面提高消化病学教学质量,培养高素质和创新型消化病学人才.

Objective To compare the distribution and concentration of matrix metalloproteinases-2 (MMP-2) in different dentin depth of premolar and molar of young people.Methods Freshly extracted human premolars and molars (aged between 20-30) were sectioned to 1.5 mm thick slices along the longitudinal axis of the tooth separately.Enamel and pulp of each slice was removed,and then the premolar and molar slices were respectively divided into two subgroups according to superficial or deep dentin and pulverized to fine powder.After dentin protein was extracted,the concentrations of MMP-2 in different tooth were detected using fluorescent microsphere immunoassay.Results The content of MMP-2 in superficial layer dentin of premolar was (0.022 ± 0.006) ng/mg.The content of MMP-2 in deep layer dentin of premolar was (2.087 ± 0.090) ng/mg.The content of MMP-2 in superficial layer dentin of molar was (0.336 ± 0.037) ng/mg.The content of MMP-2 in deep layer dentin of molar was (3.312 ± 0.308) ng/mg.Conclusions MMP-2 exists in human coronal dentin.In the same type of teeth of young people,the concentration of MMP-2 in deep dentin was significant higher than those in superficial dentin.In the same dentin depth,the concentration of MMP-2 in molar was significant higher than those in premolar.

AIM:To study the bond strength and the morphology of hybrid layers between dentin and composite resin bonded by ethanol-wet bonding method.METHODS:Standard dentin slices were prepared.The dentin slices were randomized into 4 groups according to bonding techniques(water and ethanol-wet bonding) and dental adhesives [Single Bond 2(SB) and Prime Bond NT(PB) ].After etching and rinsing,dentin surfaces were treated by water-moist and ethanol respectively.Then SB and PB were respectively applied,composite build- ups were made.The bonded sampls were prepared into beams for microtensile bond strength evaluation with or without NaOCl challenge.Morphology of hybrid layer was observed by SEM.5 samples were used for each experiment.RESULTS:Compared with water-wet bonding,ethanol- wet bonding yielded comparable(P 0.05 for PB) or higher(P 0.05 for SB) 24 h bond strength,displayed significantly higher bond strength after chemical challenge(P 0.05,for the two adhesives),and produced more integrate and uniform hybrid layers.CONCLUSION:Ethanol-wet bonding can improve the bonding efficiency of contemporary etch-and-rinse adhesives,probably due to the good structure of hybrid layer.

Esthetic restoration using resinous materials has achieved great success in the past decade.A large part of this success is attributed to the significant advances in adhesive materials. Although refinement of existing adhesive materials is still required to improve bonding reliability and reproducibility, the development of innovative adhesives with bioprotective/biopromoting functions has been recognized as an important direction for future research. Until now, significant achievements have been made in the development of adhesives that can protect the bonded interface from extrinsic bacteria- or intrinsic enzyme-induced destruction, as well as those that can promote the natural remineralization or regeneration process of the tooth tissue. In this review, the author will summarize the latest developments in these innovative bioactive adhesive materials.

The effect of air blowing pressure on the bonding interfacial micro morphology and micro-tensile bonding strength of resin/dentine in the two-step self-etch bond system was investigated.The occlusal enamel of 20 teeth was removed, then the teeth were randomly divided into 4 groups based on the different bonding procedures. After 24 hours in water bath at 37℃, one slab from each tooth was collected and then examined with scanning electron microscope (SEM) results (n=5). 8 sticks from each tooth were collected, then tested the micro-tensile bond strengths (μTBS) (n=40).SEM results shows that the first group’s adhesive layer is the thickest, while resin tags are the shortest and sparsest; the fourth group’s adhesive layer is the thinnest, while resin tags are the longest and densest; the second group and third group fall in between. The order of μTBS is: the second group>the third group>the first group>the fourth group.The air blowing pressure influences resin/dentine bond strength significantly in the two-step self-etch bond system.

OBJECTIVE:To compare the distribution and concentrations of matrix metalloproteinase (MMP)-1, 2, 3, 8, 9 in human coronal dentin.METHODS:The localization of five types of MMP was performed using immunohistochemistry. Molars were demineralized and sectioned into 5 µm thick specimens. All specimens were randomly divided into five groups according to the antibodies. Each group contained two subgroups (n = 6). Immunoreactivity of each subgroup was visualized with 3, 3-diaminobenzidine solution or fluorescein isothiocyanate and observed under microscopy respectively. Molars were sectioned into slices. The slices were divided into two groups according to superficial or deep dentin and pulverized to fine powder. After dentin protein was extracted, the concentrations of MMP-1, 2, 3, 8, 9 were detected by using fluorescent microsphere immunoassay.RESULTS:Immunohistochemical staining revealed that MMP-1, 2, 3, 8, 9 were highly concentrated in the deep dentin. However, intense immunoreactivities of MMP-2, 8, 9 were identified in a 6-10 µm wide zone adjacent to the dentino-enamel junction. The content of MMP-1 in superficial layer and deep layer of dentin were (0.037±0.025) and (0.433±0.089) ng/mg. The content of MMP-2 in superficial layer and deep layer of dentin were (0.445±0.115) and (2.730±0.712) ng/mg. The content of MMP-3 in superficial layer and deep layer of dentin were (0.071±0.069) and (0.460±0.108) ng/mg. The content of MMP-8 in superficial layer and deep layer of dentin were (0.586±0.246) and (6.159±0.948) ng/mg. The content of MMP-9 in superficial layer and deep layer of dentin were (0.384±0.185) and (1.460±0.251) ng/mg. The concentrations of all tested MMP were significantly higher in deep dentin than those in superficial dentin (P < 0.05).CONCLUSIONS:There are five types of MMP contained in human coronal dentin, and the distribution of MMP shows a decreasing trend from the deep dentin to the superficial dentin.

OBJECTIVE To systematically investigate the aging effect of thermocycling, water storage and bacteria aggression on the stability of resin-dentin bonds. METHODS Forty molars were sectioned perpendicularly to the axis of the teeth to expose the middle-coronal dentin surfaces. The dentin surfaces were then treated with Single Bond 2 and made a core build-up. According to random digits table, the bonding specimens were divided into four groups (n = 10) as follows: immediate control group, aging group with thermocycling for 5 000 times, aging group with artificial saliva storage for 6 months and aging group with bacteria aggression for 14 days. The specimens in each group were then subjected to microtensile bond strengths (µTBS) testing and nanoleakage evaluation respectively. RESULTS After aging treatments, the three aging groups showed significantly lower µTBS than the immediate control group [(44.24 ± 12.75) MPa, P < 0.05]. The immediate control group also showed the lowest value of nanoleakage. The µTBS of aging group with bacteria aggression [(25.53 ± 7.39) MPa] was significantly lower than those of the other aging groups with artificial saliva storage[(29.72 ± 6.51) MPa] and thermocycling [(31.92 ± 11.87) MPa, P < 0.05]. There were no differences in the nanoleakage values among the three aging groups (P > 0.05). CONCLUSIONS All the aging treatments with artificial saliva storage, thermocycling and bacteria aggression could accelerate the degradation of bonding interfaces between an etch-and-rinse adhesive and dentin. Bacteria aggression showed the most impairing effect on the stability of resin-dentin bonds.

Objective. Quaternary amine charge density is important because when the negatively charged bacteria contact the positive quaternary amine charge, the electric balance is disturbed and the bacterium could be disrupted. There has been no report on the effects of charge density on the antibacterial efficacy of dental bonding agents. The objective of this study was to synthesize a new quaternary ammonium methacrylate, and investigate the effects of charge density of bonding agent on bacteria early-attachment, biofilm colony-forming units (CFU) and dentin bond strength.Methods. Dimethylaminododecyl methacrylate (DMAHDM) with an alkyl chain length of 16 was synthesized and mixed into Scotchbond Multi-Purpose adhesive and primer (SBMP) at mass fractions of 0%, 2.5%, 5%, 7.5%, and 10%. A microtensile dentin bond test was performed. The density of quaternary ammonium groups was measured using a fluorescein dye method. Streptococcus mutans (S. mutans) early-attachment was examined at 4 h, and biofilm colony-forming units (CFU) were measured at 2 days.Results. All groups had similar microtensile bonding strengths (mean +/- sd; n = 40) of about 60 MPa (p > 0.1). Quaternary amine charge density of bonding agents monotonically increased with increasing DMAHDM mass fraction. Bacteria early-attachment coverage greatly decreased with increasing DMAHDM content in the resin. Biofilm CFU at 10% DMAHDM was reduced by more than 4 log, compared to SBMP control. Charge density of bonding agent was inversely proportional to bacteria early-attachment coverage and biofilm CFU.Significance. Increasing the quaternary amine charge density of dentin bonding agent resin was shown to greatly reduce S. mutans attachment and decrease biofilm CFU by four orders of magnitude, without compromising the dentin bond strength. The new DMAHDM is promising for use in bonding agents and other antibacterial restorative materials to inhibit caries. Published by Elsevier Ltd on behalf of The Academy of Dental Materials. All rights reserved.

Objective: To incorporate an antibacterial monomer,methacryloxylethyl cetyl dimethyl ammonium chloride(DMAE-CB),into a pit and fissure sealant which contained a fluoride-releasing resin,and to evaluate its fluoride release properties of this DMAE-CB-incorporated sealant.Methods: DMAE-CB was incorporated into a clinically used sealant,Helioseal F.Helioseal F without DMAE-CB served as a negative control.Fluoride release from Helioseal F and Helioseal F(1% DMAE-CB) was evaluated at time intervals of 4,8,12,and 24 hours and 2,3,7,14,28,56,and 112 days with a fluoride combination electrode.Results: Fluoride was released from the evaluated sealants with a similar pattern.Both materials released measurable amounts of fluoride throughout the test period,with considerable amounts of fluoride released in the first 24 h and especially during the first 4 h.Conclusion: The incorporation of DMAE-CB had no adverse influence on the fluoride release from Helioseal F which contained a fluoride-releasing resin.The long-term and effective antibacterial activity by mean of the incorporation of antibacterial monomer is feasible.

Objective To understand occupational values of military grass-root health workers,to provide theoretical basis for the management of military grass-root health workers.Methods Super's work values inventory (WVI) revised by NING Wei-wei,which included three indexes:extrinsic value,intrinsic value and extrinsic rewards,as well as 15 factors,was used to investigate 71 health workers coming from 16 military grassroots units.Results Among the 15 factors,the top five was interpersonal relationship (first) in extrinsic value,life style (second) in extrinsic rewards,accomplishment (third),altruism (fourth) and independence (fifth)in intrinsic value,and the last five was aesthetic feeling (eleventh),intelligence inspiration (twelfth),creativity (fourteenth) and management (fifteenth) in intrinsic value,and variability (thirteenth) in extrinsic value.The scores of extrinsic value,intrinsic value and extrinsic rewards of 71 military health workers were respectively (115.00 ± 15.94),(66.83 ± 8.62) and (68.25 ± 8.09).Age,working years,marital status,only children or not and registered residence before enlisting made no difference to the occupational values of military grass-root health workers (P ＞ 0.05).Conclusions Military grass-root managers should give more support and assistance on colleague relationship,life style,achievement,altruism,independence and other fields.As for the fact that health workers pay little attention to intrinsic values like aesthetic feeling,intelligence inspiration,creativity and management,education on humanistic quality,innovation and management ability should be strengthen.

OBJECTIVES:This study examined the use of methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB) as a potential matrix metalloproteinases (MMPs) inhibitor on both soluble recombinant and dentine matrix-bound endogenous MMPs, meanwhile attempted to determine the effective anti-MMP group of quaternary ammonium methacrylates (QAMs). METHODS:The possible inhibitory effects of five DMAE-CB mass concentrations (0.1%, 0.5%, 1%, 3%, 5%) on soluble rhMMP-9 were measured using a colorimetic assay kit. Methyl methacrylate (MMA) and [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METMAC) were also screened against rhMMP-9 to compare the inhibitory effect with DMAE-CB. Matrix-bound endogenous MMP-activity was evaluated in completely demineralized dentine beams. Thirty beams were randomly divided into three groups (N=10) and respectively placed into 500μL of calcium- and zinc-containing media (CM; control), 0.2% chlorhexidine or 3% DMAE-CB in CM aged for 30 days. The changes in modulus of elasticity, loss of dry mass and solubilization of collagen peptides were measured via three-point bending, precision weighing and hydroxyproline assay, respectively. RESULTS:0.5-5% mass concentrations of DMAE-CB were highly effective (P<0.05) in inhibiting rhMMP-9 varied between 76.56±6.44% and 97.06±3.24%, the inhibitory effect of MMA was much lower than that of METMAC and DMAE-CB at the same concentration (P<0.05). Dentine beams incubated in 3% DMAE-CB showed only a 26.34% decrease in the modulus of elasticity (75.74% decrease in control), a 1.72±1.56% loss of dry mass (29.70±9.12% loss in control), and significantly less solubilized hydroxyproline when compared with the control (P<0.05). CONCLUSIONS:DMAE-CB is effective in inhibiting both soluble recombinant MMPs and matrix-bound dentine MMPs. Quaternary ammonium group is the effective anti-MMP group of QAMs. CLINICAL SIGNIFICANCE:The incorporation of DMAE-CB into dental adhesives has the potential to enhance the durability of dentine bonding and thus increases the longevity of restorations.

近20年来,牙科粘接技术和粘接材料发展迅猛.现有的牙本质粘接剂已具备理想的即刻粘接性能,但牙本质粘接界面的长期稳定性仍是制约粘接修复体使用寿命的一个重要因素.如何提高牙本质粘接界面的稳定性,是目前口腔粘接领域亟待解决的问题. 粘接剂树脂单体渗入部分脱矿的牙本质基质中,并与胶原纤维网形成紧密结合的交联,单体固化后形成混合层,是牙本质粘接的基础.混合层的质量直接影响牙本质粘接界面的稳定性[1],影响混合层质量的因素,包括粘接剂性能、粘接剂在牙本质界面的渗透性及其与胶原纤维的结合性、胶原纤维的长期稳定性等,成为决定牙本质粘接界面稳定性的关键因素.现根据以上影响因素对提高牙本质粘接稳定性的方法进行综述.

OBJECTIVE To evaluate the anti-matrix metalloproteinase (MMP) activity of a novel crosslinking quaternary ammonium methacrylates, 2-methacryloxylethyl dodecylmethyl ammonium bromide (MAE-DB). METHODS The effects of MAE-DB at different concentrations (1%, 3%, 5%, 7%) on soluble matrix metalloproteinase-8 (MMP-8) were investigated using fluorescent assay kit. Readings were taken every 20 min for 3 h. The 1, 10-phenanthroline provided by the assay kit served as control group. Demineralized dentin beams were randomly divided into three groups (n = 50) and immersed in different solutions: artificial saliva, MAE-DB incorporated artificial saliva and chlorhexidine incorporated artificial saliva. After temperature cycling, the changes of ultimate tensile strength were measured to determine the effect of MAE-DB on the activity of matrix-bound endogenous matrix metalloproteinases. The morphology of dentin collagen fibrils in the three groups was observed via transmission electron microscopy (TEM). RESULTS MAE-DB could effectively inhibit the activity of soluble MMP-8. The inhibition percentage of 3% MAE-DB was 99.53% after 1 h, and it was significantly higher than that of 1, 10-phenanthroline (95.71%, P < 0.05). After temperature cycling, the ultimate tensile strengths of MAE-DB groups were significantly higher than those of the artificial saliva groups and the chlorhexidine groups (P < 0.05). TEM micrographs of MAE-DB group revealed that the microstructure of the collagen fibrillar was intact, while the fibrillar in the artificial saliva group was disrupted, indicating a protective function of MAE-DB on dentin collagen. CONCLUSIONS MAE-DB can inhibit the activity of MMP and protect dentin collagen from enzyme degradation.