尖牙

Abstract〕Objective:To study the tooth size correlation between permanent cuspid and bicuspid group and other teeth groups in malocclusion.

摘要〕 目的：研究错、正常的尖牙、双尖牙组与其它组牙的相关性，为尖牙、双尖牙组的预测提供科学依据。

Results:In normal occlusion,the size of cuspid and bicuspid group was correlated with that of mandibular incisor group in accord with the principle of Moyers prediction.

结果：正常的尖牙、双尖牙组与下切牙组高度相关，符合Moyers预测机理，但错的尖牙、双尖牙组一般与同牙列的切牙加第一磨牙组高度正相关。

Results The incidence of wedge-shaped defects reached 97.3 %,and the frequency of involved teeth was:first premolar,second premolar,first molar,cuspid.

结果 该组老年人楔状缺损的发病率为97 。3 %，且随年龄递增；楔状缺损的好发部位和缺损程度第一双尖牙列首位，其次为第二双尖牙，第一磨牙；其中第一磨牙比以往人们认为的尖牙更好发楔状缺损。

The first three largest number of missing teeth is as follows: maxillary first molar, maxillary second molar and mandibular first molar. The first three largest number of resident teeth is as follows: mandibular cuspid, mandibular bicuspid and maxillary cuspid. The cases without occusal relationship account for 19.51%; and the cases which need occlusal reconstruction or occlusal elevation account for 19.51% of all the cases, while food impaction exists in 21.84% cases.

结果：本组老年人平均缺失牙齿9.10颗，缺失最多的前3位牙齿是上颌第一磨牙、上颌第二磨牙和下颌第一磨牙；余留最多的前3位牙齿是下颌尖牙、下颌第一双尖牙和上颌尖牙。19.51%的病例颌骨间无咬合接触关系，19.51%的病例修复时需咬合重建或咬合抬高；21.84%的病例修复前存在食物嵌塞。

When we select the abutments, we must pay addi- tional attention to the periodontium of premolar.

在选择固定桥基牙时，双尖牙要特别重视其牙周组织的健康，对于牙槽骨吸收的双尖牙必须增加基牙以减轻其负荷。

When the proportion of force to moment is 1∶4.7, the canine will translational move distally. To reinforce anchorage with second molar can prevent anchorage teeth movement mesially during canine distal movement.

要使尖牙平行远中移动，远中牵引力与力矩的最佳比例为 1∶4.7；将第二双尖牙、第一、第二磨牙连成整体，可减小尖牙远中移动时的支抗消耗。

Upper central incisors moved forward and downward together with maxillary, at the same time they upright in the sagittal plane and tip mesially. 3 The occlusion plane rotated clockwise for about 1.5°. 4 The width increasement effect of RME comes from approximately the equal amounts of skeletal and dental expansion. The mode of dental movement was a combination of body and tipping movements of posterior teeth.

结果：1后牙在宽度方向上为整体移动和倾斜移动相结合的移动方式，但第一磨牙和第一双尖牙稍有差别；牙齿和骨对宽度增加的贡献各占约1/2；2后牙在垂直方向有伸长的趋势；3第一磨牙和第一双尖牙均向前整体移动，轴倾度保持不变；4中切牙整体随上颌骨前部向前向下移动，其牙长轴发生直立，轴倾度增加；5上颌平面发生顺时针旋转。

The clinical characters of oligodontia concluded from this study are following:(1) There is significant difference that more teeth absent and more existent teeth anomalies in patients of oligodontia/S group than in patients of oligodontia/I group, and the peg-shaped upper lateral incisor is the most frequently affected teeth with shape anomaly.(2) Both of the two groups have no significant differences in number of teeth missing between maxilla and mandible as well as that between left and right side.(3) The distribution of teeth missing is bilateral symmetry in both groups, but the frequency of teeth lost are different: excluding the third molar, in oligodontia/I group, the lower second premolar is the most frequently congenitally missing tooth followed by the upper lateral incisor, while in oligodontia/S group, the most frequently missing teeth are mandibular canine and maxillary lateral incisor. Nevertheless, the first molars are the most stable teeth in both groups.(4) In oligodonita/I group, the mean mesiodistal dimensions of all type of existent teeth are significantly smaller than normal value. It is implied that oligodontia is not an isolated phenomenon, but is related to a complex of other dental changes.

对于口腔多个恒牙先天缺失的临床特点有以下初步结论：(1)综合征型先天缺牙患者较单纯型先天缺牙患者恒牙缺失数目更多，平均分别为23.9个和14.9个，且现存牙齿有更多的形态异常，分别为7／10例（70％）和6／22例（27.3％），其中最常见的是上颌侧切牙畸形；(2)两种类型的多个恒牙先天缺失患者的缺牙数目在上下颌及左右侧之间均无差别；(3)两种类型的多个恒牙先天缺失患者在缺失牙位上均呈对称分布，但在具体牙位上有所差异：不计第三磨牙，单纯型先天缺牙最常缺失的牙位是下颌第二双尖牙、其次为上颌侧切牙；而综合征型先天缺牙最常缺失的牙位是下颌尖牙和上颌侧切牙；无论何种情况，第一磨牙均为牙列中最稳定的牙齿；(4)在单纯型先天缺牙患者中，现存恒牙的牙冠宽度较国人正常值偏小，差异显著，提示牙齿形态与多个牙先天缺失有一定相关性。

A group: to measure the length of root canal by Root ZX, prepare the root canal and test the trial point for a best position of the major Gutta Percha Point in root canal obturation with lateral compaction, then take X-ray photos.

随机选择需行根管治疗术的单根管恒前牙、双尖牙 2 30颗，分为A、B两组，A组采用RootZX 根管测量仪测量根管长度，根管预备后，根管充填时加试尖步骤，调试出最适主尖后侧压充填根管，摄牙片

After bridge insertion, the pontic of fixed bridge re- stored additional force, but the change of stress in the peri- odontium of premolar and molar is very diffierent.

固定桥修复后桥体承受了增加的载荷，双尖牙和磨牙牙周膜应力的变化规律是不相同的，双尖牙牙周膜应力的增加幅度大于磨牙。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失