暨南大学口腔组织病理学15章牙齿萌出ppt课件

Chapter 15 Tooth eruption and shedding of deciduous teeth 沈 丽 佳 主 讲,Oral Histology & Embryology,1,Chapter 15 Tooth eruption and shedding of deciduous teeth,I. Definition: II. Eruption of the deciduous teeth III. Shedding of the deciduous teeth IV. Clinical consideration Discussion,2,I. Definition,Eruption Shedding/exfoliation Development of the dentitions,3,1. Eruption,Eruption is essentially the process whereby a tooth moves from its developmental position in the jaw into its functional position in the mouth.,4,2. Shedding/exfoliation,For the eruption of a permanent tooth, where there is a deciduous predecessor, the root of the deciduous tooth must be resorbed to allow for shedding. The eruptive pathway of the permanent teeth is very much related to the shedding or exfoliation of the deciduous teeth. It is largely pressure from the erupting successional tooth which determines the pattern of deciduous tooth resorption.,5,4/1/2019,6,3. Development of the dentitions,Description of the development of the dentitions requires consideration of the processes of tooth eruption and of the development of occlusion post-eruptively. Three distinct lead to he establishment of the full dentition: Pre- eruptive tooth movement Eruptive tooth movement Post-eruptive tooth movement,II. Tooth eruption,Pattern of tooth movement Histology of tooth movement Mechanism of tooth movement,7,(I). Pattern of tooth movement,Pre-eruptive tooth movement Eruptive tooth movement Post-eruptive tooth movement,8,4/1/2019,9,Definition Pre-eruptive tooth movement of deciduous teeth Pre-eruptive tooth movement of permanent teeth Summary,1. Preeruptive tooth movement,乳牙胚的萌出前移动,颌骨的发育使牙胚随之在作相应的移动。 乳牙胚 拥挤 颌骨生长 缓解 特点 颌骨长度增加 磨牙胚向后移动， 前牙胚向 前移动。 颌骨宽度和高度增加，下颌牙胚向上、向外移动， 上颌牙胚向下、向外移动。,1. Pre-eruptive tooth movement,定义 乳牙胚的萌出前移动 恒牙胚的萌出前移动 结论,11,Definition 定义,Pre-eruptive phase, which starts with the initiation of tooth development. 萌出前移动是指牙齿在开始萌出前，乳牙胚和恒牙胚在颌骨组织内的移动。,4/1/2019,13,Pre-eruptive tooth movement of deciduous teeth:,When deciduous tooth germs first differentiate, there is a good deal of space between them. Because of their rapid growth, this available space is utilized and the developing teeth become crowded together, especially in the incisor and canine region. This crowding is reliveved by growth in the length of the infant jaws, which provides room for the second deciduous molars to drift backward and anterior teeth to drift forward. At the same time the tooth germs also move outward as the jaws increase in width, and upward( downward in the upper jaw) as the jaws increase in height.,4/1/2019,14,Pre-eruptive tooth movement of permanent teeth:,Permanent teeth with deciduous predecessors also undergo complex movements before they rech the position from which they will erupt. The permanent incisors and canines first develop lingual to the deciduous tooth germs at the level of their occlusal surfaces and in the same bony crypt. As their deciduous predecessorss erupt, they move to more apical position and occupy their own bony crypts. Permanent molars also move considerablely from the site of their initial differentiation. All these movements are linked to jaw growth and may be considered as movements positioning the tooth and its crypt within the jaws preparatory to tooth eruption.,Summary,All pattern of tooth movement are relatively to development of the jaws.,结论,牙齿萌出前的所有这些移动 都与颌骨的生长发育有关。,恒牙胚的萌出前移动,切牙、尖牙在乳牙胚舌侧发育 (在同一骨窝内及同一牙合面) 当乳牙萌出时，恒牙胚位于乳牙 的舌侧根方，占居自己的骨窝。 前磨牙胚（双尖牙）位于乳牙胚的舌侧， 当乳磨牙萌出时,前磨牙胚位于乳牙磨牙 的根分叉处，占居自己的骨窝。 恒磨牙是由牙板向远中增生，形成增加牙板而发育形成的。,2. Eruptive tooth movement,Tooth eruption (pre-functional phase) which begins once the roots begin to form. 定义: 萌出移动是指牙齿从颌骨内移到咬牙合功能位置上的过程。,4/1/2019,19,Eruptive tooth movement,During the phase of eruptive tooth movement the tooth moves from its position within the bone of the jaw to its functional position in occlusion and the principal direction of movement is occlusal or axial . It is important to recognize that jaw growth is normally occurring while most teeth are erupting, so that movement in planes other than axial is superimposed on eruptive movement.,4/1/2019,20,Definition: After the teeth have emerged into the oral cavity, there is a protracted phase concerned with the development and maintenance of occlusion (the functional phase). maintain the position of the erupted tooth while the jaw continues to grow compensate for occlusal wear. compensate for interproximal wear.,3. Post-eruptive tooth movement,3. Post-eruptive tooth movement,定义：萌出后移动是指已萌出的牙齿为保 持其咬牙合位置并补偿牙齿咬牙合 面和邻面磨耗的移动。 包括： 在颌骨继续生长期间保持已萌出牙齿的位置。 补偿牙合面的磨耗。 补偿邻面的磨耗。,(II) Histology of tooth movement,Pre-eruptive phase Eruptive phase Post-eruptive phase,1. Pre-eruptive phase,Total bodily movement of the germ There is its excentric growth: one part of the developing tooth germ remains stationary while the remainder continues to grow, leading to a shift in its center.,2. Eruptive phase,During the eruptive phase of physiologic tooth movement, significant developmental changes occur: Formation of root Formation of periodontal ligament Formation of dentogingival junction Formation of gubernacular canal or Gubernacular cord.,3. Post-eruptive phase,In the Post-eruptive phase the tooth makes movements after eruption whose primary function is to accommodate the growth of the jaws. The principal movement is in an axial direction. It occurs most actively between the ages of 14-18 and is associated with condylar growth, which separates the jaws and teeth.,（III） Mechanism of tooth movement,Bone growth Ligament traction Root growth Vascular pressure,4/1/2019,27,（III） Mechanism of tooth movement,牙齿周围骨组织的改造 牙周膜细胞或纤维或两者共同作用 牙根的形成 流体力学作用,III. Shedding of deciduous teeth,Patten of Shedding Histology of Shedding Mechanism of resorption and shedding,4/1/2019,29,Pattern of Shedding,For a deciduous incisor or canine, root resorption initially occurs on the lingual surface adjacent to the developing permanent tooth. With subsequent movement and relocation of the teeth in the growing jaws, the developing permanent tooth comes to lie directly beneath the deciduous tooth and further resorption occurs from the apex.,4/1/2019,30,Pattern of Shedding,For a deciduous molar, root resorption often commences on the inner surfaces where the permanent premolars initially develop. The premolars later come to lie beneath the roots of the deciduous molar and further resorption occurs from the root apices. The shift in position of the deciduous tooth relative to the permanent successor may account for the intermittent nature of root resorption.,4/1/2019,31,Histology of Shedding,The initiation of root resorption may be an inherent developmental process or it may be related to pressure from the permanent successor against the overlying bone or tooth. To assess which of these explanations is correct, permanent tooth germs have been surgically removed, when it was seen that resorption of the deciduous predecessors still occurred, though this was delayed. These findings are also consistent with the clinical observation that shedding of a deciduous tooth still occurs but is retarded where the successor is congenitally absent or occupies an abnormal position within the jaw.,IV. Clinical consideration,发育中的颌骨、牙槽骨、牙周韧带具有 高度的弹性组织在不断改建，并且这种组织改建可受多方面因素影响. 人类牙齿萌出时间有一定的变化范围，萌出时间显著超出此范围时，被视为萌出异常。 人类的颌骨发育有逐渐变小的趋势，因此造成牙列拥挤、阻生或埋伏。 最常见的阻生牙依次为 、3 3、 、8 8。 8 8 5 5,IV. Clinical consideration,牙齿萌出时，邻近结缔组织有急性炎症。 乳牙残余 乳牙滞留 乳牙埋伏 在恒牙萌出和乳牙脱落 的替换期应注意的问题,萌 出 异 常,乳牙早脱 局部 邻牙移位阻挡了恒牙萌出（阻生） 因素 严重创伤、牙胚损伤 萌出 牙胚与骨粘连强直 延迟 营养不良：vitD 缺乏 全身 先天性疾病、遗传因素: 因素 内分泌紊乱： 脑下垂体和甲状腺功能不足 患某些传染病：麻疹、高热,乳牙滞留原因,相应的恒牙缺失。 恒牙阻生、强直或恒牙位置不正而造成 最容易发生乳牙滞留的是上颌侧切牙、上、下颌第二乳磨牙。,在恒牙萌出和乳牙脱落的替换期应注意的问题,乳牙龋病的治疗不能忽视。 龋病过早脱落恒牙萌出延迟咬牙合 关系紊乱 牙髓 、 根尖病 影响恒牙的发育,next,在恒牙萌出和乳牙脱落的替换期应注意的问题,6岁以上儿童正处在混合牙列期。 恒牙萌出延迟、乳牙滞留，应及时拔除乳牙，使恒牙在正常位置萌出。 第一恒磨牙龋坏严重时，如果第二恒磨牙的牙根未形成或形成1/3时，可将6牙拔除，第二恒磨牙代替6牙。但如果第二恒磨牙根已形成1/2或将要萌出，则要保留6牙一直到第二恒磨牙萌出后才能拔6牙，否则要做间隙保持器。,思考题,1. 牙齿生长发育过程中的生理性移动包括几个阶段？ 2. 乳牙胚和恒牙胚在萌出前移动的方式和特点。 3. 牙齿在萌出前期和萌出期的组织学变化。 4. 乳牙吸收和脱落的方式和机制。 5. 牙萌出延迟的原因有哪些？ 6. 乳牙滞留的原因有哪些？ 7. 哪些牙位易发生阻生牙？ 8. 在临床上混合牙列期应注意哪些问题？,4/1/2019,39,参 考 文 献,牙体牙髓牙周病学杂志 2000；10（1）：39 牙体牙髓牙周病学杂志 2000；10（2）：100 牙体牙髓牙周病学杂志 2001；11（1）：57 牙体牙髓牙周病学杂志 2001；11（5）：341 牙体牙髓牙周病学杂志 2002；12（8）：452 中华口腔医学杂志 2001；36（3）：236 中华口腔医学杂志 2001；36（3）：236 现代口腔医学杂志 2001；15（5）：396 国外医学口腔医学分册 2002；29（2）：112,4/1/2019,40,NB 3mo 9mo 2yr,4/1/2019,41,41/2 yr 6yr 9yr,4/1/2019,42,NB 9mo 11/2yr 2yr,3yr 41/2yr 11yr 14yr,4/1/2019,43,Skull of 4-year-old child,4/1/2019,44,massons trichrome, x300,Late bell stage(appositinal stage),4/1/2019,46,4/1/2019,47,The developing root,The pulp-limiting membrane,4/1/2019,49,4/1/2019,50,4/1/2019,52,Principal collagen fibers associated with an erupting permanent tooth,The soft tissues overlying