Silane effects on luting resin bond to a Ni---Cr alloy

This study investigates the effect of a silane coupling agent on the shear bond strength of four commercially available resin luting systems (two of which rely on mechanical retention and two which have a chemical bond to metal) when bonding a prepared Ni---Cr alloy to etched bovine enamel. Silane application reduced the bond strengths of the two chemically adhesive resins and increased the bond strength of one of the mechanically retained resins. For the other mechanically retained resin, silane application did not significantly increase the bond strength but the plane of fracture changed from resin/metal to resin/enamel: from this an increase in metal resin bond strength can be inferred.     

标准冠内固位体在口腔固定修复领域中的初步应用

目的：探讨成品专用固位体在口腔修复领域中应用的可行性。方法：用荷兰产微型气动弯手机和特制钻头在缺牙两侧基牙近远中面钻孔。将成品专用钛合金冠内固位体粘接在基牙邻面上，制取精确印模，灌制带专用固位体代型的工作模型，铸造抗力桥架并烤瓷人造牙制作固定桥，并将此固位体用于固位条件不良的全冠、桩冠、种植义齿的辅助固位。结果：共制作188例各类固定修复体，其中无冠式固定桥98例，配合全冠制作的固定桥62例，桩冠20例，人工种植牙1例，全冠7例。因适应症选择不当或不规范操作造成在20个月内共6例无冠式固定桥发生松动脱落。结论：此法具有磨牙少、痛苦小、省时简便等优点。也可用于辅助固位。     

老年人楔状缺损临床治疗评价

目的:总结老年人楔状缺损治疗特点及最有效的方法。方法:选择60岁以上的老年人178例共452颗楔状缺损牙齿,用不同的材料进行临床治疗研究。结果:Dyract复合体与Seal&ProtectTM脱敏剂共同修复楔状缺损在临床上取得很好效果。结论:老年人楔状缺损是常见病、多发病,Dyract复合体与Seal&ProtectTM脱敏剂是一种较好的修复方法。     

Fracture strength of all-ceramic posterior inlay-retained fixed partial dentures

OBJECTIVES: The purpose of this in vitro study was to compare the quasi-static (QSFS) and fatigue fracture strength of all-ceramic resin-bonded three unit inlay-retained fixed partial dentures (IRFPDs) made from a heat-pressed lithium-disilicate based glass-ceramic (LDGC) and a CAD/CAM-manufactured yttrium-oxide partially stabilized zirconia framework (YPSZ). METHODS: Identical IRFPD-models of the maxilla were used. They consisted of a second premolar, a missing first molar and a second molar (Co-Cr-Mo alloy) integrated in a low melting alloy base. Roots were covered with a soft silicone-layer to simulate an artificial parodontium. Premolars had an occlusal-distal inlay-preparation and molars a mesial-occlusal inlay-preparation. Thirty-two IRFPDs were made from each ceramic using two different connector dimensions: 3mmx3mm (LDGC_9, YPSZ_9); 4mmx4mm (LDGC_16, YPSZ_16). All IRFPDs were cemented adhesively to the IRFPD-models, using composite resin cement. QSFS was tested in a universal-testing-machine (UTM) for six specimens. The other specimens were fatigued either with cyclic loading at 250N (n=4) in a chewing simulator or at 600N (n=6) using the UTM, and group YPSZ additionally at 1500N. RESULTS: The medians of QSFS (N) were 960 (LDGC_9), 1316 (LDGC_16), 3180 (YPSZ_9) and 3120 (YPSZ_16). For both QSFS and cyclic loading significant differences were found between LDGC_9 and LDGC_16 (p0.05). Differences between LDGC and YPSZ were significant for both connector sizes (p相似文献   

后牙成品螺纹桩核与铸造桩核临床应用比较

目的：比较后牙成品螺纹桩核与铸造桩核的临床应用比较。方法：通过5年的使用观察，比较成品螺纹桩核与铸造桩核固位力和核的强度。结果：成品螺纹桩核与铸造桩核固位和核的强度无明显差别（P＞0．05）。结论：成品螺纹桩＋树脂核是一种简便易行，效果良好的临床修复方法。     

Analysis of 154 cases of teeth with cracks

Abstract –  It is well known that cracked teeth occur most frequently in the mandibular molars with large or poor restorations, in those over 50 years of age. However, with increasing knowledge and experience with cracks of teeth, cracks appear to be found frequently in intact teeth without restorations. The aim of this study is to analyze the cases of tooth cracks in a dental hospital in a year, and to find out the characteristic features of cracks of teeth. For 1 year, each tooth that were identified as a cracked tooth was recorded and analyzed in terms of the classification of cavity and restorative material, the nature of opposing tooth, the location in the arch, the age and gender, and the clinical signs and symptoms, and treatment result. Cracked teeth were observed most frequently in the teeth with no restorations (60.4%) and with class I restorations (29.2%). The most prevalent age was in those over 40 years of age (31.2% in their 40s, 26.6% in their 50s) and the prevalence was similar in men (53.9%) and women (46.1%). Cracked teeth were found most frequently in the maxillary molars (33.8% in first molar, 23.4% in second molar) than in the mandibular molars (20.1% in first molar, 16.2% in second molar). 96.1% of the cracked teeth responded to the bite test, and 81.1% of the cracked teeth were observed in the mesiodistal direction. The prevalence of cracked tooth was highest in the intact teeth with no restoration, in maxillary molars, and in those over 40 years of age. When examining a intact maxillary posterior tooth that is sensitive to a bite and thermal change, crack in the mesiodistal direction need to be considered one of the causes.     

Reduced dental plaque accumulation on composite gold alloy margins

Restoration of tooth surfaces with materials that inhibit formation of heavy bacterial plaque accumulations could be important in the treatment of patients with existing oral disease or in reducing the likelihood for periodontal disease. Captek is a dental gold composite material used to produce copings for ceramometal restorations that has been reported to inhibit plaque accumulation. In this study, the oral bacteria of nine periodontally healthy subjects with a total of 42 gold composite copings were sampled. Contralateral teeth with normal tooth surfaces were also sampled as controls. The quantitative presence of forty bacteria was determined in each sample by DNA:DNA hybridization. The results indicated that the porcelain/gold composite alloy coping surfaces had significantly fewer bacteria than the control normal tooth surfaces (71% reduction). The percentage composition, however, did not differ significantly between surfaces.     

Clinical evaluation of two "packable" posterior composite resins: two-year results

The purpose of this study was to evaluate the clinical performance of two "packable" posterior composites: Prodigy Condensable/Optibond Solo—Kerr (PC-OS) and Definite/Etch & Prime—Degussa (D-EP). Thirty-six patients participated in this study. A total of 78 restorations (40 with D-EP and 38 with PC-OS) were made. Each patient received at least two restorations (one of each studied material). The materials were handled according to the manufacturer's instructions. The occlusal adjustments were made at the placement visit. The restorations were finished and polished after 1 week. They were evaluated at baseline, and after 1 year and 2 years by two independent evaluators using the USPHS criteria. Colored slides were made of all the restorations. After 2 years, 34 patients and 74 restorations (38 with D-EP and 36 with PC-OS) were available for evaluation. A total of 50% of PC-OS restorations received A criterion and 50% received B criterion (2.8% color, 11.1% marginal staining, 27.8% superficial staining, 2.8% anatomic form and 5.6% marginal adaptation). For D-EP, 60.5% of restorations received A criterion and 39.5% received B criterion (2.6% color, 5.3% marginal staining, 10.5% superficial staining, 7.9% anatomic form and 13.2% marginal adaptation). The C criterion was observed only for marginal adaptation with D-EP (2 restorations—5.3%). The obtained data were tabulated and statistically analyzed using the Fisher, Chi-square and McNemar tests. After 2 years, PC-OS showed a significant increase in superficial and marginal staining. For D-EP the marginal adaptation and superficial staining became significantly worse than baseline.     

数字化比色仪在口腔修复中的应用

色彩精确并且符合人们审美要求的修复体是每个牙医师追求的目标,牙比色也是修复治疗中最具挑战的环节。由于视觉比色在实际进行过程中受到环境以及主观因素的明显影响,仅使用传统比色板已不能满足需求。为了解决这一问题,数字化选色系统应运而生,但也存在一定的缺点和局限性。本文对数字化牙选色技术及相关问题作一综述,旨在对临床修复工作和科研提供帮助。     

Laboratory-fabricated, acrylic resin cylinders for fixed, provisional implant restorations

Commercially produced provisional cylinders are commonly used during fabrication of fixed, provisional implant restorations. A procedure is presented for the fabrication of fixed, provisional implant restorations using laboratory-fabricated, autopolymerizing acrylic resin cylinders. These cylinders offer a number of advantages over commercially produced cylinders and may reduce the treatment cost of implant prosthodontics.