第三节牙的萌出和替换

Designed and produced by Dr. Wang Li
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牙的萌出 萌出期：
Designed and produced by Dr. Wang Li
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牙的萌出
牙的萌出：
萌出过程：
Designed and produced by Dr. Wang Li
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牙的萌出
3. 萌出后期（功能性萌出期）
B, Permanent tooth;
C, Bony partition
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牙的萌出
萌出过程
A, Erupted deciduous tooth;
B, Permanent tooth
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乳恒牙交替
乳恒牙交替：
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乳恒牙交替
乳恒牙交替：
Designed and produced by Dr. Wang Li
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乳恒牙交替
乳恒牙交替：
Designed and produced by Dr. Wang Li
随颌骨的生长，乳牙胚向前庭方向和咬合面移动， 恒牙胚在乳牙舌侧发育。恒磨牙随颌骨的生长改 变位置
牙胚萌出前移动的方式： 整体移动 一部分固定，其他部分生长：如上皮隔
Designed and produced by Dr. Wang Li
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牙的萌出
Designed and produced by Dr. Wang Li
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牙的萌出
牙的萌出是一逐步的断续的过程，使支 持组织与牙的萌出移动相协调。
牙刚建立咬合时，不稳定易发生咬合异 常。若儿童养成不良习惯，如咬唇、吮手 指等均能使牙齿发生牙异位畸形。
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牙的萌出
4. 牙萌出移动的机制： 复杂 多种因素
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牙的发育
总结： 牙发育的全过程与机体内外环境密切
相关，如营养、代谢、疾病、内分泌等， 若上述紊乱则影响牙的发育及萌出。
牙的保健从发育期开始
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牙根的形成 液体的压力 牙周围骨组织的吸收及有选择的沉积 牙周膜的细胞或纤维或两者共同将牙向颌面
牵拉：最主要的力量来源
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二、乳恒牙交替
6-12岁
乳牙的作用：
刺激牙弓、颌骨发育 引导恒牙的萌出
乳牙脱落：牙根的
吸收
Designed and produced by Dr. Wang Li
Designed and produced by Dr. Wang Li
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牙的萌出
萌出过程
A, Erupting incisor during pre-functional eruptive stage;
B, Permanent incisor;
C, Basal bone.
Designed and produced by Dr. Wang Li
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牙的萌出
2.萌出期：
缩余釉上皮的保护 上皮袖 引导索
幼儿上腭的乳牙舌侧可见恒牙萌出的引导管
来自百度文库
Designed and produced by Dr. Wang Li
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牙的萌出
2.萌出期：
缩余釉上皮的保护 上皮袖 引导索 主动萌出-牙颌向运动 被动萌出-牙龈的根方移动 结合上皮 牙尖进入口腔后，牙根的一半或3/4都已形 成。
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乳恒牙交替
乳恒牙交替：
582 years old
Designed and produced by Dr. Wang Li
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三、牙萌出的次序和时间
1. 牙萌出有一定次序，并与牙胚发育的 先后基本一致
2. 牙萌出有较恒定的时间性 3. 左右同名牙大致同时出龈 4. 下颌牙萌出略早于上颌同名牙
改建：牙咬合建立后，牙槽骨密度增加、牙周 膜主纤维束形成
根尖孔由喇叭口状----狭窄 一生中牙颌面不断磨损-牙轻微颌向、侧向移 动补偿
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牙的萌出
萌出过程
A, Enamel organ; B, Dental lamina; C, Basal bone
第三节 牙的萌出和替换
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一、牙的萌出
概念：eruption 指牙突破口腔黏膜的现象 分期：
萌出前期 萌 出 期 萌出后期
Designed and produced by Dr. Wang Li
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牙的萌出
1.萌出前期：
牙根形成时牙胚在牙槽骨中的移动
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牙的萌出
萌出过程
A, Erupting incisor;
B, Permanent incisor;
C, Reduced enamel epithelium
Designed and produced by Dr. Wang Li
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牙的萌出
萌出过程
A, Erupted deciduous tooth;