前磨牙

Paleoanthropologist David Strait of the University at Albany in New York state and his colleagues found that A. africanus evolved jaws, teeth, and a face that would have been particularly good at withstanding large forces on its premolars—precisely the place where humans and other primates crack large objects, such as nuts that are too big to chew with our molars.

纽约州奥尔巴尼大学古人类学家戴维·斯特雷特和他的同事发现，南方古猿非洲种的颌骨、牙齿和脸经过演化，其前磨牙特别擅长经受极大的力气——人类和其他灵长类动物恰好就用前磨牙来咬碎像坚果一样的大块食物，大到我们的磨牙无法咀嚼。

Methods: 50 maxillary first premolar and 60 maxillary second premolar were included in the study.

挑选拔除的50颗上颌第一前磨牙及60颗上颌第二前磨牙。

Results: Relative diagnostic accordance rate of the clinical exploration and four kinds of image processing setup was the highest（P＞0.01）in the first premolars. Relative diagnostic accordance rate of the clinical exploration and the pseudocolor image setup and negative image setup was the highest（P＞0.01）, and that of the clinical exploration and the pseudo3D image setup and positive image setup was the lowest（P＜ 0.01）, showing statistical differences in the second premolars.

结果：①第一前磨牙：4种图像处理格局下邻面龋的检出结果与临床诊断结果的符合率高，差异无统计学意义（P＞0.01）；②第二前磨牙：负片和伪彩图像格局下邻面龋的检出结果与临床诊断结果的符合率高，差异无统计学意义（P＞0.01）；③正片和伪3D图像格局检出结果和临床诊断结果的符合率低（P＜0.01）。

In the soft tissue measurements, the value of soft tissue facial angle and B'-Pos-FH in the first extraction group was less than those in the second extraction group significantly. After treatment all the patients had an increase in S-Ns-Pos angle, soft tissue facial angle, B'-Pos-FH and depth of mentolabial groove. At the same time, soft tissue convexity angle was diminished obviously. But the change was not significant between the two premolar extraction groups.

2在对软组织项目的测量中，治疗前第一前磨牙拔除组的软组织面角、颏沟倾角均小于第二前磨牙拔除组，治疗后2组均出现软组织面凸角减少，颏凸角、软组织面角、颏沟倾角、颏唇沟深度增加；但2组在各项测量项目的变化上无显著组间差别。

Methods:7 cases of classⅡ,division 1 maloclusion were treated.Upper first premolar and lower second premolars were extracted in all cases.Lower first molars were mesially moved by means of segmental arch. Cephalometric analysis was used to evaluate the effects of the treatment.

应用片段弓技术对7例安氏Ⅱ类1分类患者，通过拔除上颌第一前磨牙及下颌第二前磨牙，使下颌第一磨牙较快地向近中移动，纠正磨牙Ⅱ类错牙合关系。

Anchorage loss measured at the first premolar averaged 1.3 mm,but the crowns tipped 3.5?distally.During distalization with Distal jet,the first premolar did not tend to tip mesially as found in many investigation of other intraoral distalizing appliance.

每侧第一前磨牙的支抗丧失平均为1.3mm并伴3.5 的牙冠远中倾斜，这一结果不同于其它口内磨牙远移装置所造成的前磨牙牙冠近中倾斜，与国外对同类矫治器的观察结果相似。

METHODS: Sixty-nine extracted mandibular first premolars and 93 mandibular second premolars were used.Radiographs of teeth in mesiodistal direction were taken.

离体第一前磨牙69个，第二前磨牙93个，摄近中远中向的X线片，用Photoshop5.0软件分析根管，用Weine氏法测量根管的弯曲度，测量角度大于18度时，则认为根管存在明显的弯曲，根管的构型采用Vertucci分类法。

Methods: Fifty-fix adolescents were chosen and divided into first premolar extraction and nonextraction groups, with 30 and 26 patients respectively. The pretreatment and posttreatment panoramic radiographs were taken. The indexes of third molar eruption space, distance from third molar to occlusal plane and the length of mandible were measured and analyzed.

选择56例上下颌第三磨牙均存在的患者进行方丝弓正畸治疗，按照第一前磨牙拔除与否分为拔牙组（30例）和非拔牙组（26例），利用术前术后曲面断层片对患者上下颌第三磨牙萌出间隙、第三磨牙与胎平面的距离以及下颌长度进行测量分析。

Chondrocytes isolated from the same calf suspended in 30% pluronic were then"painted"onto the articular surface of the scaffold and implanted into subcutaneous pockets on the dorsa of athymic mice.

实验三，在犬双侧下颌第三、四前磨牙和第一磨牙颊侧制备根向深5mm的颊侧骨上袋型牙槽骨缺损动物模型。

Objective: To study the changes of upper and lower third molar position in patients treated with first premolars extractions.

目的：研究第一前磨牙拔除后对第三磨牙位置变化的影响，探讨影响第三磨牙萌出的客观因素。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。