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??Composite resins are widely used as clinical restoration materials because of good aesthetic properties??easy handling??thermal insulation and better conservation of tooth structures. However??its polymerization shrinkage can lead to the gap between the tooth structure and composite resin called microleakage??which can result in the failure of restorations. Cervical lesions usually have little enamel in Class?? cavities??so it’s more difficult to avoid the microleakage. Microleakage is a complicated process caused by various factors and there are many studies about it reported. Based on literature reviews??this paper summarized the influence factors of microleakage in Class?? composite restorations??hoping to offer some reference and help in clinical treatment.     

Fracture resistance and stress distribution in endodontically treated maxillary premolars restored with composite resin.

PURPOSE: The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. MATERIALS AND METHODS: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). RESULTS: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 +/- 25.4); G2 (52.7 +/- 20.2); G3 (82.1 +/- 24.9); G4 (40.2 +/- 14.2); G5 (64.5 +/- 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. CONCLUSIONS: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.     

后牙病理性磨损树脂修复的临床效果探讨

目的:观察用直接树脂充填法和间接树脂充填法修复后牙病理性磨损的临床效果。方法:选择后牙牙合面有病理性磨损且具有充填空间的患者48例,患牙144颗,其中有牙本质过敏症状者38例98颗牙。患者按门诊顺序随机分为直接法修复组和间接法修复组2组各24例,在不备洞的情况下分别采用可乐丽菲露复合树脂直接或间接修复,比较治疗3个月及1年后树脂充填的临床效果、牙本质敏感情况和咀嚼效率改变情况。结果:治疗后3个月时复查,直接法和间接法两组患牙树脂充填体A级率无显著性差异(卡方检验,P>0.05);治疗1年后复查,间接法组患牙树脂充填体A级率优于直接法组,两组差异有统计学意义(卡方检验,P<0.05)。间接法组牙本质敏感治疗总有效率优于直接法组,两组差异有统计学意义(卡方检验,P<0.05)。治疗3个月及治疗1年后,间接法组的咀嚼效率高于直接法,两组差异有统计学意义(t检验,P<0.01)。结论:间接树脂法比直接树脂充填法修复后牙病理性磨损有较好的临床效果。     

流动树脂的研究进展

流动复合树脂又称流动树脂,从1995年问世至今,其在临床上的应用日益广泛,在垫底、衬垫、窝沟封闭等方面有着较广泛的应用。流动树脂与传统复合树脂相比,填料含量较低,各种性能也随之改变。本文就流动树脂的临床应用及性能作一综述。     

低聚合收缩复合树脂的性能及其应用

聚合收缩是复合树脂的主要缺陷之一,易引起复合树脂与牙体之间形成间隙,产生釉质裂纹和牙尖移动,导致充填失败。近年来,一种以矽油基底基环氧化物为基质成分的新型复合树脂,以低聚合收缩率为特点,成为研究的热点。本文就这种新型复合树脂的性能和粘接等方面作一综述。     

复合树脂充填窝洞聚合收缩应力的控制

目前,用于窝洞充填的光固化复合树脂均存在一定的聚合收缩,其收缩应力在临床中会导致牙体变形、术后敏感、微渗漏和继发龋等问题,从而影响充填修复的效果。下面就复合树脂充填窝洞聚合收缩应力的主要影响因素和临床操作中的控制方法等研究进展作一综述。     

复合树脂聚合收缩应力的研究进展

复合树脂作为常用的牙色充填材料,具有美观、操作方便等优点,但也存在聚合收缩、不耐磨、变色等问题.其中,聚合收缩可引起充填复合树脂与牙体之间形成间隙、釉质裂纹和牙尖移动,导致充填失败.影响收缩应力大小的因素包括复合树脂的组成、窝洞形态和临床操作.通过减小聚合收缩应力可提高复合树脂充填的成功率.     

Comparative bond strengths of autopolymerising denture resin and light cured composite resin to denture teeth

AIM: To investigate the shear bond strengths between light cured composite and autopolymerised acrylic resin bonded to acrylic resin denture teeth. METHODS: Surface treatments were used for the denture teeth included wetting with methylmethacrylate (MMA) monomer, composite bonding agent and acid etching. The samples were divided into seven groups. Two groups of specimens were immersed in distilled water for 30 days to hydrate the teeth. Five other groups of embedded denture teeth were stored in air at room temperature for 30 days. RESULTS: Analysis of variance indicated statistically significant differences between groups (P < 0.001). CONCLUSION: The greatest bond strengths to denture teeth were in acrylic resins polymerised with pressure and wetted with monomer. The bond strengths of hydrated and unhydrated samples gave similar results both with acrylic resins and composites.     

新型基质材料在降低光固化复合树脂体积收缩方面的研究进展

光固化复合树脂在口腔临床中应用广泛,但光固化过程中产生的体积收缩和收缩应力影响了临床修复效果。树脂基质作为复合树脂的主体成分,对树脂的性能有着重要影响,而树脂基质一般由主要单体和低粘度的稀释性单体聚合而成。研究人员试图通过改进树脂基质中的单体,降低复合树脂的体积收缩及收缩应力,增强机械性能,提高临床修复效果。该文就最近几年树脂基质单体的研究进展作简要综述。     

Direct posterior composite resin restorations: A review. 2. Clinical technique

Despite the increased use of composite resin to restore posterior teeth, there is evidence that clinicians should be selective in their use of these restorations. This paper describes the clinical technique--preparatory procedures, preparation of the cavity, preparation for placement of composite resin, placement of composite resin and finishing of the restoration--for the relatively conservative use of composite resin in posterior teeth and reviews the literature to discuss briefly many of the controversial aspects of the technique.     

老年患者后牙残冠钛合金成品桩和树脂核修复的临床效果观察

目的：评价钛合金成品桩和树脂核用于后牙残冠修复的效果。方法：选择120例患者180颗需要进行桩核冠修复的患牙,使用成品钛合金桩、流动树脂进行桩核修复,再进行冠修复。分别观察1个月、3个月、6个月、12个月和24个月,进行效果评价。结果：修复1个月、3个月、6个月后,修复成功率为100%,12个月时有3例患者失访,修复体成功率为100%。24个月时5例患者失访,修复体成功率为97.1%。结论：成品钛合金与树脂核的应用可有效的保留患牙。适宜在县级基层医院推广使用。