基质金属蛋白酶-7和c-myc在口腔鳞状细胞癌中的表达和意义

目的研究基质金属蛋白酶-7(MMP-7)与c-myc在口腔鳞状细胞癌组织中的表达及其意义。方法应用免疫组化EliVisionTM法分别检测MMP-7和c-myc在49例口腔鳞状细胞癌和5例正常口腔黏膜上皮中的表达情况。结果1)MMP-7和c-myc在口腔鳞状细胞癌组织中的阳性表达率分别为83.7%和77.6%。2)在不同病理分级、不同临床分期和有无淋巴转移的口腔鳞状细胞癌组织中MMP-7阳性表达率的差异有统计学意义(P<0.05)。3)在不同病理分级和有无淋巴转移的口腔鳞状细胞癌组织中c-myc阳性表达率的差异亦有统计学意义(P<0.05)。4)口腔鳞状细胞癌组织中MMP-7和c-myc的表达呈正相关(P<0.05)。结论MMP-7和c-myc在口腔鳞状细胞癌组织中均有高表达,在口腔鳞状细胞癌的发病过程中,其高表达具有协同效应,共同促进口腔鳞状细胞癌的发生和发展。     

中国北京和日本横滨两地青少年正畸治疗认知程度的调查分析

通过调查中国北京地区和日本横滨地区青少年对错(牙合)畸形的认知情况,探讨不同地区青少年对正畸治疗的理解和认识差异.方法对中国北京地区5500名青少年和日本横滨地区4646名青少年进行关于错(牙合)畸形认知情况的问卷调查,并进行χ<'2>检验.结果北京地区回收问卷3964份(72.1%),横滨地区回收问卷3291份(70.8%).北京地区已行正畸治疗的青少年为753例(19.0%),横滨地区为467例(14.2%),差异有统计学意义(P<0.001).79.2%已行正畸治疗的横滨青少年认为做正畸治疗好,比北京(66.0%)高.不同年龄段横滨青少年对正畸治疗需较长时间的了解程度均高于同年龄段北京青少年.与北京青少年(494名,65.7%)相比,更高比例的横滨青少年(370名,78.6%)认为(牙合)畸形会对面部健康带来不利影响.结论横滨地区行正畸治疗的青少年比例比北京地区小,但更多的横滨青少年认为做正畸治疗好,高于北京青少年.横滨青少年对正畸治疗的认知程度高于北京,且横滨青少年更注重错牙(牙合)畸形对面部健康的影响.     

成人单侧后牙反患者髁突的对称性及矫治后髁突位置的变化

目的:探讨成人单侧后牙反患者髁突的对称性及矫治后髁突位置(R)的变化。方法:21例成功矫治的单侧后牙反成年患者作为实验组,男10例,女11例,年龄18～23岁,平均21.8岁。21例安氏Ⅰ类错患者作为对照组,男10例,女11例,年龄19～23岁,平均22.1岁。实验组矫治前后与对照组均拍摄全颌曲面断层片和双侧矫正薛氏位片,测量髁突的不对称指数和髁突在关节窝中的相对位置。结果:实验组两侧髁突高度(CH)不对称,与对照组相比,CH的不对称指数明显增大(P<0.05)。实验组矫治前后两侧髁突在关节窝中的位置均无显著性差异,但与矫治前相比,矫治后非反侧髁突相对位置由前位趋于正中位(R由13.52减小为9.48)。结论:成人单侧后牙反患者的髁突形态存在不对称性,而髁突位置相对对称,颞下颌关节可随咬合关系和下颌骨位置的变化发生改建;正畸治疗后髁突位置更加协调。     

应用植入控释系统进行一次法根管治疗术的动物实验研究

目的：利用自制含氯霉素、甲硝唑等药物的控释系统，对实验家兔的血药浓度、药物抗菌活性和家兔根管、尖周组织的病理观察，为今后临床应用提供理论和实验依据。方法：应用组织病理观察和液相色谱分析技术。结果：用ＨＰＬＣ法得出实验用家兔血药浓度和抗菌活性均为阴性，根管及尖周组织病理切片无特殊表现。结论：自制控释系统是一种无毒、无副作用、有效的根管治疗药物剂型，可进行临床应用。     

改良失活法在牙髓炎疼痛控制中的临床效果

目的:比较改进多聚甲醛牙髓失活法与传统失活法的临床效果,并观察其在60岁以上老年人的效果差异.方法:观察两种方法在A、B两个年龄组间牙髓失活时疼痛发生率、牙龈坏死、所封失活剂能否被完整取出、牙髓失活效果以及去除冠髓时牙髓出血情况,并作统计学分析.结果:两个年龄组改良方法疼痛发生率均低于传统方法(P＜0.01).A组改良法失活效果优于传统法(P＜0.01);B组改良法与传统法差异无显著性(P＞0.05).改良法失活剂完整取出率高于传统法(P＜0.01);两个年龄组间差异均无显著性(P＞0.05).各组均没有牙龈坏死情况.结论:改良法优于传统法.可以有效提高牙髓失活效果,降低疼痛等并发症的发生,缩短患牙的疗程.     

山羊颞下颌关节盘细胞透射电镜观察

目的 用透射电镜的方法对两只1月龄健康山羊四只颞下颌关节盘的细胞及胶原结构进行了观察.方法 切取山羊双侧颞下颌关节盘,经组织学处理后行透射电镜观察细胞和胶原超微结构特征.结果 颞下颌关节盘由不均分布的细胞和胶原纤维组成,细胞有成纤维细胞样细胞和软骨细胞样细胞两种,其中成纤维细胞样细胞较软骨细胞样细胞占优势.成纤维细胞样细胞表现有细长的突起,核大,梭形或不规则形,细胞器较少.软骨细胞样细胞胞核呈圆形或椭圆形,周围少有电子透射区,细胞膜不明显,胞突少见.胶原纤维由平行排列的有周期性横纹特征的胶原原纤维组成.结论 颞下颌关节盘细胞有成纤维细胞样和软骨细胞样细胞两种,前者占优势,胶原原纤维表现有周期性横纹特征.这为颞下颌关节盘组织工程研究中细胞来源及表型分析奠定了一定基础.     

Placement and replacement of restorations in general dental practice in Iceland

Ninety-one Icelandic practicing dentists (51% response rate) provided information related to the reasons for placement and replacement of 8,395 restorations and 741 sealants in 5,997 patients. Information included the patient's gender and age, the clinician's gender and experience in years since graduation, the defined criteria for replacement of restorations, the estimated past use of material in five-year increments and the records of 100 consecutively placed restorations. The materials used include composite (52.7%), amalgam (29.2%), glass ionomer (9.5%), resin-modified glass ionomer (7.1%) and other materials (1.4%). Although material selection was independent of the clinician's gender, female patients received more composite and fewer amalgam restorations than their male counterparts. Reasons for placing restorations comprised replacement of failed restorations (47.2%), primary caries (45.3%) and non-carious defects (7.5%). Secondary caries was the main reason for replacement for all types of restorations. Chi square analysis related to the dependence between the reasons for replacement and clinician's experience showed that more experienced clinicians recorded a lower frequency of secondary caries than less experienced ones (p<0.0001), while the diagnoses of discoloration and fracture of restorations increased with the clinicians' experience (p<0.0001).     

1354 freshmen's dental investigation]

1354 freshmen have been investigated to discover the relationship between dental diseases and environments,living habits and personal sanitary conditions,because urban young men like sweet foods and snacks,the incidence of caries is greater in the cities than in the country,more people with tetracycline discolored tooth live in urban areas than in the rustic ones,which is due to dense living conditions, vulnerable to respiratory organs disease,medical conditions and convenience of taking tetracycline when ill;on the other hand,gingivitis is more common within the country students than within the city students,for those students from the country are used to brush their tooth after adolescence and usually have more dental calculus which is harmful to the gingiva.More than half of the investigated freshmen are ignorant of correct method of brushing and oral health and that is important factors of high rate of dental disease,according to the above reasons,the effective measures should educated to prevent dental disease.     

Mechanical behavior of ProTaper universal F2 finishing file under various curvature conditions: a finite element analysis study

Introduction

The purpose of this study was to visualize the stresses and strain distribution patterns in ProTaper Universal F2 files (Dentsply Maillefer, Ballaigues, Switzerland) and to establish the stress- and strain-curvature relationship for this instrument under various conditions by using a dynamic, three-dimensional finite-element model.

Methods

An accurate geometric model of a ProTaper Universal F2 instrument was created. Two short, straight tubes were also modeled to represent the parts of root canal apical and coronal to the curvature. Then, the file was constrained to a curve of varying degree, curve length, and position. The maximum von Mises stress and strain on the tension side of the instrument was measured at 5-degree intervals in a numerical simulation package (LS-DYNA; Livermore Software Technology, Livermore, CA).

Results

The mechanical performance of the ProTaper F2 file under various conditions was simulated. A long curvature length produced lower values of stress and strain under the same angle of curvature. An increase in the curvature angle generally induces higher stress and strain. For the same degree and curve length, the stress and strain increased if the curved portion was situated further up the shaft of the instrument (ie, with a larger diameter).

Conclusions

The dynamic, numerical model may be used to evaluate and compare the effect of various root canal curvatures on the behavior of different designs of root canal instrument. The magnitude of stress and strain imposed on the instrument is influenced by the abruptness and degree of curvature as well as the location of the curved portion.