Tooth wear, a proposal for an evaluation system

The present-day terminology and definitions of tooth wear are not unambiguous. For diagnosing tooth wear, however, it is essential that they are unambiguous. In this article a proposal is presented for a tooth wear evaluation system with simplified definitions. This system consists ofa number of modules and can be used for various aspects of the diagnostic procedure. It can be used for the quantification of tooth wear, both for periodic screening and for the monitoring of tooth wear in individual patients. The scoring of occlusal/incisal tooth wear as well as of non-occlusal/non-incisal tooth wear is possible. The evaluative system is also suitable for determining which type of tooth wear, such as attrition, abrasion and erosion, is most likely to have caused any observed loss of hard tooth tissue.     

A model for the prediction of tooth wear in individuals

BACKGROUND: Easily applied, age-specific standards are useful in assisting clinicians to decide whether the extent of tooth wear observed in a given patient at a specific age is acceptable or whether intervention is indicated. METHOD: A simple method of scoring tooth wear and previously established mathematical relationships between tooth wear scores and age, provide the basis of a method for predicting tooth wear scores. In its most specific form, the method can be used to predict tooth wear scores for individual patients at subsequent ages. Alternatively, tables or graphs can be consulted to provide a less precise prediction of tooth wear that can assist clinicians to decide whether the amount of wear reflects high, moderate or low rates of wear at the specified age. CONCLUSION: In cases where there is no reason to believe that aetiological factors have changed significantly over time, data obtained from the methods described can assist clinicians to plan appropriate management for patients presenting with unacceptable levels of tooth wear.     

Bioengineered teeth from cultured rat tooth bud cells

The recent bioengineering of complex tooth structures from pig tooth bud tissues suggests the potential for the regeneration of mammalian dental tissues. We have improved tooth bioengineering methods by comparing the utility of cultured rat tooth bud cells obtained from three- to seven-day post-natal (dpn) rats for tooth-tissue-engineering applications. Cell-seeded biodegradable scaffolds were grown in the omenta of adult rat hosts for 12 wks, then harvested. Analyses of 12-week implant tissues demonstrated that dissociated 4-dpn rat tooth bud cells seeded for 1 hr onto PGA or PLGA scaffolds generated bioengineered tooth tissues most reliably. We conclude that tooth-tissue-engineering methods can be used to generate both pig and rat tooth tissues. Furthermore, our ability to bioengineer tooth structures from cultured tooth bud cells suggests that dental epithelial and mesenchymal stem cells can be maintained in vitro for at least 6 days.     

遗传性因素对牙齿发育的影响

牙齿发育作为全身发育的一部分,具有多基因遗传的特点,环境因素也可通过影响基因的表型而使牙齿发育表现多种多样.目前研究发现多种遗传性疾病都能影响到牙齿的发育,表现为牙齿结构、形态、数目和萌出等方面的异常.本文对遗传性因素影响牙齿正常发育的研究现状作一综述.     

栓道式混合支持型种植固定义齿

由于种植体与自然牙支持组织的差异，种植学界对自然牙和种植体混合支持式固定义齿有较多争议。作者在自然牙人造冠设计栓体，在种植体支持的冠式桥体上设计栓道。种植义齿通过栓体栓道与自然基牙上的人造冠形成混合支持式义齿。当义齿承负力时，自然基牙与种植义齿又可有相对独立运动，使应力中断。临床应用表明，这种设计可以有效地解决自然牙和种植体支持组织的不均衡及在力作用下弹性变形不均衡，导致自然基牙松动，及种植体骨界面损害的问题；又可使义齿保持可折邻结构，便于种植体的清洁和护理。作者认为这种混合支持式义齿的咬合面颊舌径应为自然牙列的３／５至２／３为宜。     

Atraumatic tooth preparation

One of the tenets of operative dentistry is to maintain the health and vitality of teeth whenever possible. Methods of tooth preparation can adversely affect the tooth structure and the pulp. This paper will review the research on methods and devices used to prepare teeth, the possible sequelae of tooth preparation, and the best methods that can be recommended from the research to maintain tooth vitality and marginal integrity.     

影响牙齿美白效果的因素

牙齿美白技术在口腔临床诊疗中的应用日益广泛,以漂白技术为主的非侵入性牙齿美白因其独特的不破坏牙体硬组织的优越性,成为许多牙齿着色患者的选择。不同类型着色牙能达到的美白效果不一样,其中四环素牙的漂白疗效不及氟斑牙。过氧化氢漂白剂与含同等浓度过氧化氢的过氧化脲漂白剂的漂白效果接近,而在过氧化物漂白剂中加入诸如菠萝蛋白酶等无过氧化物试剂能提高牙齿美白效果;低浓度的漂白剂延长作用时间能达到高浓度漂白剂的牙齿美白效果。目前pH值对牙齿美白效果的影响仍存有争议;激光与传统的过氧化物漂白剂结合能有效提高牙齿美白效果;联合牙釉质微研磨与过氧化物牙齿漂白剂能使氟斑牙的美白效果更佳。本综述通过分析牙齿着色原因、漂白剂的性质、激光微研磨的应用及漂白后牙齿组织的改变探讨以漂白技术为主的非侵入性牙齿美白效果的影响因素。     

非常规拔牙矫治在正畸临床中的应用

在正畸临床中,有很大比例的患者需要减数拔牙矫治,常见的减数方案为拔除上下左右的同名前磨牙,但当患者存在严重的龋坏牙、牙外伤、埋伏阻生牙或者畸形牙时,首先要考虑拔除这些牙齿。原则上,任何牙齿都可能成为减数对象,但在临床设计时, 应结合患者的错牙合类型、牙齿所能提供的间隙及牙齿的健康状况等进行综合考虑。本文对正畸临床中非常规拔牙矫治做一综述。     

泌尿及内分泌系统和代谢性疾病患者拔牙的风险及防治

泌尿及内分泌系统和代谢性疾病的临床症状和体征会干扰此类患者拔牙操作的正常进行。此外,拔牙过程也可能会加重患者系统性疾病的临床症状,且围手术期用药亦可能对系统性疾病治疗所用药物造成影响。文章针对泌尿及内分泌系统和代谢性疾病患者拔牙可能出现的风险及其预防和处理进行阐述,以期为口腔医生在临床工作中能够对此类患者安全、顺利地实施牙拔除术提供参考。     

Trauma to the primary dentition

The guiding principle in managing trauma to the primary dentition is potential sequelae to the permanent tooth. If the risk to the permanent tooth is great, the primary tooth should be removed. If esthetics are a concern to the parent, a number of appliances can be fabricated to temporarily manage this issue. It is important that parents realize that the desire to maintain optimum esthetics by maintaining a significantly injured primary tooth can, in many cases, cause more damage to the permanent tooth. Where avulsions have occurred, the old adage "when in doubt, leave it out" is still perhaps the most reliable advice.     

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邻牙、对颌牙及颞下颌关节损伤是牙拔除术中较为严重的并发症,一旦发生,易引发医患矛盾。本文针对邻牙、对颌牙以及颞下颌关节损伤的原因、临床表现、处理和预防进行阐述,为口腔外科医生的临床操作提供参考。     

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?? In clinical work?? it's common to meet patients treated by extracting teeth?? most of which are the four first premolars. But for patients with  severe tooth cavities??tooth trauma??impacted tooth and tooth deformity et al?? they can't be treated by this orthodontic extraction mode. In principle any tooth can be extracted?? but in clinical work?? the malocclusion ??space and tooth with special conditions should be considered. This review attempts to address the clinical application of unconventional tooth extraction in orthodontic treatment.     

白细胞介素1加速兔牙齿移动的实验研究

为探讨白细胞介素１（ｉｎｔｅｒｌｅｕｋｉｎ１，ＩＬ－１）对正畸牙齿移动的影响及对牙槽骨的作用，选用１２只大耳白兔分为２组，一组为对照组，另一组注射ＩＬ－１。对２组动物进行牙齿移动距离的测量、破骨细胞计数和组织学观察。结果表明：ＩＬ－１能够加速正畸牙齿移动，可以增加牙周组织中的破骨细胞，并能加速牙槽骨的改建。     

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??The procedure of tooth extraction can be affected by urinary system diseases??endocrine system diseases or metabolic diseases. On the other hand??the process of tooth extraction can also make the symptoms of these diseases worse. Furthermore??the medications used in tooth extraction may interact with those used for systemic diseases. Thus??the aim of this paper is to review the risks of tooth extraction when dealing with patients with urinary system diseases??endocrine system diseases or metabolic diseases??in order to provide reference for the safe and smooth tooth extraction.     

预成金属冠在隐裂牙治疗中的应用

目的 在治疗隐裂牙引起的牙髓炎或根尖周炎前用预成金属冠,用以防止治疗过程中及治疗后牙体折断。方法选择在口腔门诊首次就诊的具有牙髓炎或根尖周炎症状的隐裂牙,采用预成金属冠修复后再作牙髓病治疗。结果 用预成金属冠治疗的牙髓炎、根尖周炎的患牙的保存和咀嚼功能均较好。结论 预成金属冠在隐裂所引起的牙髓炎及根尖周炎的治疗中的作用是明显的,在治疗后应及时用铸造或烤瓷冠修复。     

Numerical simulation of orthodontic bone remodeling

Orthodontic tooth movement is the result of alveolar bone remodeling due to response to mechanical stimulus at the interface with periodontal ligament. Therefore, periodontal ligament plays a critical role in the orthodontic tooth movement. The present study sought to develop a numerical model capable of simulating orthodontic bone remodeling. A three-dimensional finite elements model of mandibular incisor has been constructed based on CT data from a 15-year-old boy prior to orthodontic treatment. Simulations of orthodontic tooth movement were performed for tooth translation (bodily movement). The normal strain of periodontal ligament was assumed to be the key mechanical stimulus for alveolar bone remodeling. As bone remodeling is an iterative procedure, tooth position and the geometry of tooth supporting structures were updated at each iteration. The results indicated that the total amount of tooth movement after a 30-day therapy period was approximately 0.9 mm, which was in good agreement with clinical observations. Therefore, orthodontic bone remodeling, and consequently, orthodontic tooth movement can be simulated using finite elements method. These simulations can be used in treatment planning strategy and predicting clinical tooth movement.     

呼吸及免疫系统疾病患者拔牙的风险及防治

呼吸及免疫系统疾病的临床症状和体征会干扰此类患者拔牙操作的正常进行。此外,拔牙过程也可能会加重患者系统性疾病的临床症状,且围手术期用药亦可能对系统性疾病治疗所用药物造成影响。文章针对呼吸及免疫系统疾病患者拔牙过程中可能出现的风险及其预防和处理进行阐述,以期为口腔医生在临床工作中能够对此类患者安全、顺利地实施牙拔除术提供参考。     

牙齿漂白颜色稳定性影响因素研究进展

牙齿的漂白治疗可以改善变色牙齿的颜色,这种治疗方法越来越受到病人的欢迎,但是由于多种因素的影响,医生与病人均发现随着时间的变化,漂白后的牙齿颜色发生了反弹现象,该文就牙齿漂白颜色稳定性的影响因素做一综述。     

Integration of composite and ceramic restorations in tetracycline-bleached teeth: a case report

The success of an esthetic rehabilitation depends on the understanding of the patient's need and expectation. The management of patients with moderate to severe tetracycline-stained teeth is very challenging. Tooth whitening may be a valid alternative to more aggressive treatments; however, patients should be aware of the limitations of tooth whitening therapy. Clinicians may select differing treatment plans; tooth whitening can improve intrinsic discoloration in a way so that no further treatment is required. Once tooth whitening is completed, direct or indirect restorative procedures may be afforded to match the existing restoration with the bleached tooth structure. This article describes a conservative clinical approach to rehabilitate the smile of a patient with moderate to severe tetracycline-stained teeth using a combination of tooth whitening and direct composite and indirect porcelain restorations in the maxillary anterior segment. CLINICAL SIGNIFICANCE: The combination of tooth whitening and adhesive restorations allows clinicians a significantly more conservative approach to intrinsically stained teeth; tooth preparation for porcelain veneers and porcelain-fused-to-metal and full-ceramic crowns can be restricted to conditions in which persistent tooth discoloration or significant loss of both dentin and enamel exists.     

Centers of rotation for combined vertical and transverse tooth movements.

For purely transverse orthodontic tooth movements, the center of rotation is defined as that point on the long axis or its extension which remains stationary during the movement and around which the rotational component of the tooth displacement takes place. For tooth movements having both vertical and transverse components, no point on the long-axis line remains fixed in space. The two-dimensional theory proposed herein suggests the more general definition of the center of rotation as that point on the long-axis line which displaced the shortest distance during the tooth movement. The center of rotation can be located for the combined transverse and vertical tooth displacement. It is found to move along a path coincident with a segment of a line in a position depicting the tooth angulation midway through the movement. Formulas, which can be used in conjunction with a composite pre- and post-displacement cephalometric tracing, are presented herein to define the center-of-rotation location for such tooth movements.