Forsus�������������õ�������ѧ�о�

目的    通过建立下颌后缩三维有限元模型,探讨并分析Forsus矫治器在不同作用力值和不同作用方向对上、下颌骨位移及应力分布的影响。方法    2008年6月于西安交通大学口腔医院正畸科选取1例13岁骨性Ⅱ类下颌后缩女性患者,采用Mimics和Ansys软件结合CT技术建立该患者颌面部骨骼的三维有限元模型,模拟Forsus矫治器的作用方式在模型上进行两种加载,分别为大小不同的3组力值和方向不同的3组力值,观察颌骨和牙齿上标志点的三向位移及应力分布情况。结果    两种加载方式的3个不同加力组之间的位移差异均有统计学意义。结论    生长发育高峰期过后的患者可适当增加Forsus矫治器力值;高角、长面型患者应尽量减小Forsus矫治器作用角度。     

Notes on the current discussion on the etiology of periodontopathies]

The aetiology and the therapy of periodontal diseases are main points of stomatological research. As to the methodological approach to aetiological studies, the use of materialistic dialectic proves profitable. For example, conclusions as to therapy result from the exact analysis of and the distinction between the causes of a disease and the pathogenic factors. In this way the exact evaluation of the importance of the known pathogenic factors becomes possible. The concept of multicausality proves to be unfavourable for the orientation to priority problems in aetiological research.     

Studies on the condition of marginal periodontium depending on the shape of the bridgework body

Within an 8-years-longitudinal study 40 patients with 30 tangential and 28 open bridges were examined. The accumulation of plaque as well as the degree of inflammation of the gingiva adjacent to the bridgework binder and the bridgework bodies were determined by means of selected indices, and the data obtained were compared to those evaluated when the bridges were fitted in. The results show that the accumulation of plaque (on) with open bridge was slightly elevated as compared to tangential bridges whereas the inflammation of the gingiva was significantly increased with tangentially shaped bridgework bodies. For this reason open bridges should be used further more in areas, where aesthetics play only a secondary role.     

Effect of cadmium on the floor of the mouth on rats during lactation

Cadmium (Cd) present in the air, drinking water and food has the potential to affect the health of people, mainly those who live in highly industrialized regions. Cd affects placental function, may cross the placental barrier and directly modify fetal development. It is also excreted into milk. The body is particularly susceptible to Cd exposure during perinatal period. The effect on rat oral epithelium (floor of the mouth) after continuous exposure to drinking water containing low levels of Cd during lactation was studied. Female rats were supplied with ad libitum drinking water containing 300 mg/l of CdCl2 throughout the whole lactation period. Control animals received a similar volume of water without Cd. Lactating rats (21 day-old) were killed by lethal dose of anesthetic. The heads were retrieved, fixed in "alfac" solution (alcohol, acetic acid and formaldehyde) for 24 h, serially sectioned in frontal plane, at the level of the first molars. The 6 micro m sections were then stained with hematoxylin and eosin. Nuclear epithelium parameters were estimated, as well as cytoplasm and cell volume, nucleus/cytoplasm ratio, numeric and surface densities, and epithelial thickness. Mean body weight was 34.86 g for the control group and 18.56 g for the Cd-treated group. Histologically, the floor of the mouth epithelium was thinner in the treated group, with smaller and more numerous cells. In this experiment, Cd induced epithelial hypotrophy, indicating a direct action in oral mucosa cells, besides retarded development of the pups.     

抗生素糊剂诱导根尖形成的临床研究

目的：利用抗生素糊剂充填牙根尚未发育完成的患牙，诱导根尖继续发育形成。方法：实验组用抗生素糊剂，对照组用氢氧化钙糊剂充填根管，并于0．5—2年后复查，观察疗效。结果：实验组临床疗效理想，有效率达97％。根据统计学检验，实验组与对照组有显著差异。结论：抗生素糊剂有效地控制了根尖周组织的炎症，促使牙根继续发育，在根尖诱导形成中疗效显著。     

冠修复材料导热性对基牙牙髓健康影响的研究

目的　研究金合金、金合金烤瓷、氧化锆全瓷等修复材料的导热性对牙髓健康的影响。方法　①实验室测量金合金、金合金烤瓷、氧化锆全瓷、自体牙、树脂粘接剂的导热系数;②随访金合金烤瓷冠、金合金铸造冠（颊侧烤瓷）和氧化锆全瓷冠修复的158颗活髓牙2年;对比158颗自体邻牙,统计出现牙髓炎、根尖周炎的牙数,并与几种材料的导热系数对照。结果　树脂粘接后,86%金合金导热系数37.89W/(m?K),21颗活髓基牙出现3例牙髓炎;86%金合金烤瓷导热系数0.85W/(m?K),58颗活髓基牙出现1例牙髓炎;氧化锆全瓷导热系数0.82W/(m?K),79颗活髓基牙无牙髓炎、根尖周炎发生;天然牙导热系数0.66W/(m?K),158颗活髓基牙无牙髓炎、根尖周炎发生;86%金合金铸造冠修复的基牙牙髓炎、根尖周炎阳性率远远高于其他几种低导热系数冠修复材料基牙（P＜0.01）。结论　冠修复材料的自身导热性能够影响基牙牙髓健康,如过高会对基牙牙髓健康不利。建议把导热系数最接近天然牙的氧化锆全瓷+树脂粘接剂组合作为冠修复材料的首选。     

Study on the growth of the nose

The purpose of this study was to determine the amount and direction of nasal growth, before or during orthodontic treatment. However, the growth of the nose as a separate entity in relation to classification of cranio-facial type has not been investigated by the lateral roentgenographic cephalogram until recently. In this study, I used 2782 traces of lateral roentgenographic cephalograms to study the growth of the Japanese nose. The traces were derived from a cross-sectional study of 1,233 growth of the Japanese nose. The traces were derived from a cross-sectional study of 1,233 males and 1,549 females over 5 years and 6 months old who had not undergone the orthodontic treatment yet. Various nasal parameters were measured to study the growth of 6 linear, 2 angular nasal parameters and 1 sectional area of the external nose. The early growth in females and late growth in males were the presence of an adolescent growth spurt and the height of the maxillary prognathic type on the nasal bone and the nasal tip were longer than that of the maxillary retrognathic type. Therefore, in orthodontic treatment, the growth of the cranio-facial type should be taken into consideration before the use of orthognathic force or orthognathic surgery.     

深冷冻保存对牛牙本质力学性能影响的生物力学研究

目的:探讨不同温度不同时间深冷冻保存对牙本质力学性能的影响.方法:收集新鲜牛下颌中切牙70个,制成70个实性块状牙本质标本分7组,每组10个,A、B、C三组放在-196℃液氮中分别深冷冻保存1周、1月和6个月,D、E、F三组放在-80℃低温冰箱中分别深冷冻保存1周、1月和6个月,再与对照组G组一起测试标本的压缩强度、弹性模量、比例极限等力学性能.结果:不同温度不同时间深冷冻保存后牙本质压缩强度、弹性模量、比例极限没有明显差异.结论:深冷冻保存对牙本质的力学性能不产生影响.     

Autoradiographic investigations on the effect of cyclophosphamide on dentinogenesis of the rat incisor

abstract — Five μCi 3H-glycine/g bodyweight were administered to 10 rats 30 min prior to, and to 10 rats 24 h after 25 or 40 mg/kg of cyclophosphamide. Fourteen rats served as control material. Autoradiographic investigations of the incisors demonstrated the preodontoblasts to be the odontoblast developmental stage most sensitive to cyclophosphamide, succeeded by precursors of preodontoblasts. The injury was reflected as a reduced production of circumpulpal dentin. The sensitive period was approximately equivalent to maximally 48 h, minimally 24 h. The results were discussed in relation to those obtained with roentgen rays.     

Histomorphologic investigations on the effect of cyclophosphamide on dentinogenesis of the rat incisor

abstract — Cyclophosphamide in doses of 25, 50, 75. 100, 125, and 150 mg/kg was administered to 60 rats in 6 groups. Histomorphologic investigations of maxillary and mandibular incisors two weeks later revealed the following dose-dependent reactions: (1) interruped odontogenesis, (2) circular and mesio-distal dental constrictions, (3) niche-like dentinal defects, (4) differentiation of a postexperimental tooth, and (5) cyst formation and circulatory disturbances. Differences were observed in the frequencies of lesions in maxillary and mandibular incisors, and between labial and lingual aspects of the teeth. The results were related to roentgen irradiation effects, with which they largely concur     

深冷冻保存对离体牙牙周膜细胞活性影响的研究

目的：探讨应用不同降温方法和不同冷冻保护液的深冷冻保存技术,对人离体牙牙周膜细胞活性的影响。方法：收集新鲜拔除的人第一或第二前磨牙25颗随机分为5组;其中4组使用含海藻糖或不含海藻糖的冷冻保护液,分别应用程序降温或快速降温至－196℃,冷冻保存一周;一组新鲜拔除牙齿为对照组。分别刮取牙根面中1／3的牙周膜组织,消化法收集细胞,台盼蓝染色,高倍镜下计数活细胞数,并计算细胞存活率。结果：不同降温方法不同冷冻保护液深冷冻保存与对照组相比,牙周膜细胞存活率无明显差异。其中,使用含海藻糖的冷冻保护液程序降温的方法牙周膜细胞存活率最高。结论：应用深冷冻技术保存牙齿,牙周膜细胞的活性无明显变化,其中使用含海藻糖的冷冻保护液程序降温的方法对牙周膜细胞的活性影响最小。