根尖诱导形成术的组织学基础

根尖诱导形成术是用药物诱导牙根尚未发育完成的年轻恒牙的根尖继续发育或形成钙化屏障的技术。近年来对其诱导剂的研究较多,对其组织学基础和诱导机制的研究比较缺乏。现对其组织学基础的研究作一综述,以期为根尖诱导形成术的研究指明方向。     

丹酚酸B防治肿瘤研究进展

丹酚酸B是丹参水溶性有效成分丹酚酸中含量最高、活性最强的一种成分,研究发现丹酚酸B具有抑制肿瘤生长的活性,但是由于其高度水溶性,限制其通过生物膜,进而降低了其生物利用度,目前已有丹酚酸B纳米化的相关研究。本文对丹酚酸B防治肿瘤的研究及其纳米化的研究进展进行综述。     

颞下颌关节生物力学的理论分析方法

摘要颞下颌关节为人体最为复杂、灵活的关节之一,其生物力学研究一直是国内外学者关注的热点,也是学研究的重点。近年来随着数值分析、计算力学和信息技术等与口腔医学的日益交叉与渗透,各类研究手段和方法也层出不穷。本文综述了应用于颞下颌关节生物力学研究的理论分析方法,并分析了其存在的不足。     

CBCT在牙周病学研究中的应用

［摘要］ 锥形束CT（Cone beam computer tomography,CBCT）作为诊断工具,已被广泛应用于口腔临床及基础研究,其较低的辐射量、较高的图像质量,以及独特的三维重建功能令其在牙周病学研究中的应用日益广泛,该文就其在该领域研究中的应用作一综述。     

可降解骨折内固定物研究进展

骨折常常需要内固定物的辅助以促进愈合。传统的不可降解内固定物由于组织反应、应力遮挡等常需要二次手术取出。目前,可降解内固定物是生物材料研究领域的热点。聚乳酸作为一种较为成熟的可降解内固定物,已实际投入临床使用,由于其机械性能较差,多应用于颌骨的非承重部位。镁合金是现在可降解内固定物的研究热点,但是其降解速率过快,降解产生氢气是其主要缺点。有关锌合金内固定物的研究较少,其十分具有发展潜力,很可能成为新一代可降解内固定系统。本文将对聚乳酸、镁合金、锌合金作为内固定系统进行综述。     

对氧磷酶与牙周炎相关性研究

研究发现对氧磷酶可以保护低密度脂蛋白的氧化。目前国内外对对氧磷酶的研究主要停留在对其与心血管疾病、糖尿病相关性的研究,其活性与基因多态性被认为是动脉粥样硬化、冠心病的独立危险因素,然而对对氧磷酶与牙周病的相关性研究较少。现就对氧磷酶的生物学特征与牙周病相关性进行综述。     

环孢菌素A导致牙龈过度生长的机制研究

环孢菌素A导致牙龈过度生长的作用机制已有很多学者对其进行研究,近年来分子生物学研究成为热点。本文主要就CsA导致牙龈过度生长机制的分子生物学研究热点进行综述。     

肿瘤原发灶的治疗促进肿瘤转移的相关机制

在治疗肿瘤原发灶的各种方法日趋成熟的同时,肿瘤原发灶的治疗与其转移及转移灶的关系日益引起人们的注意.研究表明,对某些肿瘤原发灶进行根治可促进其发生转移或其转移灶的生长.本文就此问题的相关研究作一综述.     

高危型人乳头瘤病毒16E5基因对口腔肿瘤致病机制的研究进展

人乳头瘤病毒的感染是宫颈癌发病的重要危险因子之一,近些年研究表明其在口腔肿瘤及癌前病变中检出率也较高,提示其与口腔肿瘤发病有关.现有研究主要集中于其E6、E7基因的功能,其他基因涉及较少,本文对近年来兴起的对人乳头瘤病毒E5基因与口腔肿瘤关系的研究及进展作一简要综述.     

吸烟对牙种植的影响

牙种植技术在恢复牙列缺损、牙列缺失的修复治疗中取得了良好效果,并得到了广大患者的认同。但是,牙种植存在失败率的问题在一定程度上限制了其发展。自发现吸烟可影响牙种植效果以来,国内外学者对其进行了大量的研究。本文就吸烟对牙种植的影响,其作用机制及应对措施等国内外研究现状做一综述。     

Impressions for complete dentures using new silicone impression materials.

This article describes a convenient technique for making impressions of complete dentures using two newly developed silicone materials. One of these materials, a heavy-bodied silicone material, is used for simultaneous molding of all borders. The material is available in automatic mixing systems, so it can be easily and evenly applied on the tray borders. The material is designed to have a low elasticity after setting so that excess material can be carved or deficient sites corrected with a small mix. The other newly developed material, a light-bodied silicone material, possesses better flow than the usual light-bodied silicones. In addition, since viscosity is controlled and adequate flow is maintained during seating in the mouth, mucosal detail is superior.     

Trial base adapted with sealed temporary soft liner

Autopolymerizing acrylic resin is combined with temporary soft reline material to make a record base. Rigid acrylic resin is formed over a wax spacer. The wax is removed and the loose-fitting base is relined on the master cast with soft reline material. The soft material is cured in a pressure pot and sealed with a mono-poly mixture. Visible light-curing material can be used instead of autopolymerizing acrylic resin.     

A radio-opaque denture material.

The need for an acceptable radio-opaque denture material is highlighted and a new material, Opex, is described. The new material has good radio-opacity and physical and mechanical properties and may be handled as a conventional denture base material.     

Properties of a new polyether urethane dimethacrylate photoinitiated elastomeric impression material

The photoinitiated impression material is supplied premixed as a light-bodied material in a light-tight plastic syringe and as a heavy-bodied material in a tube. The impression material has excellent physical, mechanical, and clinical qualities with noteworthy long working times, short setting times, dimensional stability, accuracy, high tear strength, good wettability, biocompatibility, and ease of cold disinfection without loss of quality. The impression material is also compatible with gypsum and silver or copper metallizing baths. Accurate casts can be obtained by means of either a double-impression technique or a double-mix technique.     

Principles of biocompatibility for dental practitioners

This article is an evidence-based tutorial on the principles of biocompatibility. Although the technical issues of biocompatibility may seem beyond the scope of most practicing dentists, knowledge of these issues is fundamentally important to ensure the health of patients, dental staff members (including laboratory personnel), and practitioners themselves. Furthermore, the legal liability of dentists is often linked to biocompatibility issues. The biocompatibility of a material is not absolute; it must be measured with regard to the way the material is used. Measuring biocompatibility is a complex process that involves in vitro and in vivo tests. These tests contribute to understanding biologic responses to a material but cannot define the material's biocompatibility with 100% certainty. Practitioners should understand enough about biocompatibility testing methods to critically judge advertising claims and ask relevant questions of manufacturers. Because there is no infallible way to assess biologic response to a material, decisions about the clinical use of a material ultimately must weigh the biologic risks of a material against its potential benefits.     

Adverse reactions associated with the use of eugenol in dentistry

Eugenol is a material commonly used in dentistry with few reported side effects. It is not however, a bio-friendly material when in contact with oral soft tissues. It can produce both local irritative and cytotoxic effects, as well as hypersensitivity reactions. Here we report on two cases of adverse local reaction to eugenol, contained within a temporary restorative material and a temporary cementation material respectively, which illustrate these problems.     

An evaluation of the surface characteristics of a facial prosthetic elastomer. Part III: Wettability and hardness

Silicone facial prosthetic elastomers may cause tissue damage by abrasion. Such damage is a particular concern when prostheses are mechanically retained against tissues compromised by adjunctive therapy. The hardness and wettability of Cosmesil material was compared with that of Molloplast-B material. The stone test surfaces were separated with soap, sodium alginate, silicone paste, and left untreated. A polished stainless steel surface was prepared as a control. The specimens of Cosmesil and Molloplast-B materials were processed against each of these surfaces. Ten specimens of each material were processed against the five different surfaces. Wettability was evaluated by measuring the contact angle with a profile projector. Indentation hardness was measured with a Shore-A durometer. Statistical analysis involved multiple analyses of variation and Tukey's procedures (in all cases p less than 0.05). Molloplast-B material was found to have a higher wettability than Cosmesil material (means = 3.22 degrees higher); sodium alginate separator yielded silicone specimens with the highest wettability; Molloplast-B material was found to be harder than Cosmesil material (means = 9.75 Shore-A indentation units harder). The softest silicones were processed with soap separator. Silicone grease yielded the hardest specimens. The mechanical performance of Cosmesil material would be enhanced by increasing the surface wettability. The hardness of Cosmesil material is within the ideal range for a maxillofacial prosthetic elastomer.     

Lesions of the inferior alveolar nerve arising from endodontic treatment

A lesion of the IAN following endodontic treatment of the lower molars and premolars is not a rare event and presents an uncomfortable situation both for the dental surgeon and the patient. Injury can result on the one hand by direct intrusion of the instrument through the apex into the mandibular canal, and on the other by the filling material which becomes forced into the mandibular canal. In the latter case, a nerve lesion will only result when the filling material contains neurotoxic substances such as paraformaldehyde. With a direct lesion or when forcing of resorbable filling material into the mandibular canal is suspected, one should first employ a wait-and-see approach, because usually the only nerve damage is in the form of neuropraxy or axonotmesis for which there is a high rate of spontaneous regeneration. However, if neurotoxic filling material is introduced into the direct vicinity of the nerves, the mandibular canal should be opened and the filling material should be removed as early as possible. If the filling material is forced directly within the endoneurium between the nerve bundles, the damaged nerve sections must be resected and bridged using transplants from the sural or greater auricular nerves.     

An improved mouthguard material

a modified mouthguard material which reduces transmitted forces is described. Tests showed that the inclusion of air cells in a 4 mm thick polyvinylacetate-polyethylene (EVA) copolymer reduced the effects of impacts of less than 10 KN when compared with a material of the same EVA composition and thickness. The EVA copolymer with air-inclusions is suitable for the construction of stock, mouth-formed and vacuum-formed mouthguards. The improved elastic properties of the modified mouthguard material properties of the modified mouthguard material reduced transmitted forces by 32 per cent when copared with traditional EVA mouthguard polymers of the same thickness.     

Changes of ciscoelastic behaviour during curing of polyether rubber impression material]

To obtain a precise impression, it is indispensable to understand changes of physical property of the material used, during curing. The authors measured the viscosity and the storage modulus of polyether rubber which was recently introduced as a commercial impression material and tried to make clear the curing mechanism of the material. The less the amount of catalyst added to the base material, the more approximative is the behaviour to the first-order reaction. But according as the amount of catalyst increases the behaviour becomes not to be regarded as the first-order reaction, i.e., it is surmised that the curing reaction becomes so complicated. The more the amount of catalyst and the higher the temperature after mixing, the shorter is the setting time. The curing reaction of polyether rubber impression material is supposed to be completed in about 3 hours after mixing. Polyether rubber impression material showed the highest storage modulus among the three rubber impression materials not used, namely, polyether, polysulfide and silicone rubber. The values of this highest modulus of polyether rubber were about 2.4approximately2.8 times of those of polysulfide and silicone rubber impression material in 3 hours after mixing.