biomechanics

1、 正畸牙移動的生物機制Be the most kind and happy princess in my own realm-hh Biomechanics in orthodontics 王鐘華王鐘華 1.1.為什么能移動？為什么能移動？ 2.2.對周圍組織影響？對周圍組織影響？ 3.3.牙齒移動的規(guī)律？牙齒移動的規(guī)律？ 4.4.臨床中的生物學現(xiàn)象？臨床中的生物學現(xiàn)象？1 .Why the teeh can move ？2.What are the effects of force to the Periodontal Ligament and Bone ?3.The regular pat

2、tern of teeth movement?4.Biological phenomena connected with clinical practice?contents 正畸治療的一個首要基礎： 當有足夠的力(拉力壓力)持續(xù)的作用在一顆健康的牙齒上時，它周圍的骨組織會發(fā)生相應的改建 The orthodontic treatment is based on the simple premise that whenever pressure is applied to a healthy tooth for a sufficient long duration of time, its s

3、urrounding bone remodels. The main theories on tooth movement biomechanics 當前流行的正畸矯治的生物學機制 Sandstedt(1904) （第一個通過動物實驗研究）（第一個通過動物實驗研究）It It is observed that when the appliance with the is observed that when the appliance with the contious ligh t force of duration applied on contious ligh t force of d

4、uration applied on dog ,the bone on the pression side of the dog ,the bone on the pression side of the alveolar fossa resonpts,however,the tension alveolar fossa resonpts,however,the tension side start to deposite. When applied with side start to deposite. When applied with contiuos heavy force ,the

5、re is no resonption contiuos heavy force ,there is no resonption on the pression side .For a short time ,the on the pression side .For a short time ,the bone start an activaty called underming bone start an activaty called underming resorption,after that ,the tooth moveresorption,after that ,the too

6、th move. . 給狗戴上矯治器，發(fā)現(xiàn)牙齒在給狗戴上矯治器，發(fā)現(xiàn)牙齒在緩和持續(xù)力緩和持續(xù)力作用下，作用下，牙槽窩壓力側發(fā)生骨吸收，牽引側新骨形成。牙槽窩壓力側發(fā)生骨吸收，牽引側新骨形成。 在在持續(xù)強力持續(xù)強力作用下，壓力側牙周膜組織由于過度受作用下，壓力側牙周膜組織由于過度受壓，牙槽窩內壁反而沒有骨質吸收。短時間內會發(fā)壓，牙槽窩內壁反而沒有骨質吸收。短時間內會發(fā)生骨內吸收；繼而挖掘性吸收，最后導致牙齒移動。生骨內吸收；繼而挖掘性吸收，最后導致牙齒移動。 1 PRESSURE TENSION THEORY Schwartz proposed the pressure tension theo

7、ry in1932. This is the simplest and the most widely accepted theory.骨壓迫學說是最容易理解，也是最被廣泛接受的 1. According to this theory:Whenever a tooth is subjected to an orthodontic force, it results in areas of pressure and tension. 一但牙齒受到正畸力時，會相應在牙齒的兩側產生壓力和張力區(qū) 2.The alveolar bone is resorbed whenever the root, fo

8、r a certain length of time, causes compression of the periodon tal ligament, i.e. the pressure side. 當根側牙周膜受到足夠長時間的壓力時，會在壓迫側產生牙槽骨的吸收。 3. New alveolar bone is deposited whenever there is a stretching force acting on the periodental ligament fibers, i.e. the tension side 。而在牙周纖維膜受到牽拉一側即拉力區(qū)，會有新骨沉積。 2.B

9、LOOD FLOW THEORY I FLUID Bien (1966)has been credited for proposing the fluid dynamic or the blood flow theory.液體動力學，或者血液流動理論 According to this theory: Tooth movement occurs as a result of alterations in fluid dynamics in the periodontal ligament. 牙周膜中的液體流動,導致了牙齒的移動 牙周的內部環(huán)境： 1.Periodontal space is a

10、 confined space and the passage of fluid in and out of this space is limited. 牙周組織中的間隙是個固定大小的、有液體流動的空間.2.The contents of the periodontal ligament create a unique hydrodynamic condition resembling a hydraulic（水壓力） mechanism.牙周膜中的物質 可以創(chuàng)造了一個獨特的、類似于水壓力 的流動的條件. 3. When a force of short duration is applie

11、d to a tooth, the fluid in the periodontal space escapes through tiny vascular channels. 當短時間的持續(xù)的力量施加在牙齒上時,其牙周間隙中的液體通過小的管道流出. 牙齒受力后組織改變： 1.When an orthodontic force is applied, it results in compression of the periodontal ligament on the pressure side. The blood vessels in this region also get compr

12、essed and this results in their stenosis(狹窄）.當 牙齒受到正畸的力量時,壓力側的牙周膜受到擠壓,其中的血管會相應的變的狹窄. The blood vessels beyond the stenosis balloon up, resulting in the formation of aneurysms.而在狹窄點以外的血管就會有 相對多的血流通過,進而形成了動脈瘤樣結構 The formation of aneurysms causes the blood gases to escape into the interstitial fluid th

13、ereby creating a favorable environmentfor resorption.當動脈瘤樣結構形成時,其內部的有氧氣物質流會被擠入其他血流中,這樣,就形成了氧濃度降低，骨吸收的有利的條件2.When the force is removed, the fluid is replenished （補充）by diffusion from capillary walls and recirculation of the interstitial(空隙的） fluid. 當牙齒受到的力消失時,狹窄的血管中會由毛細血管網和再循環(huán)而來的由空隙中血流 補充.充足 的血液流動和氧濃

14、度，使得骨可以再次生成。 3.A force of greater magnitude and duration causes the interstitial fluid in the periodontal ligament space to get squeezed out and move towards the apex and cervical margins. This results in the slowing down of the tooth movement and is called the squeeze film effect 當持續(xù)的施加于牙齒的力量很大時,就會

15、導致牙周膜中的空間受到很大的擠壓力,其中的液體就會向根兩端走，而大部分流入牙齒的根尖和牙頸部,不會流進入牙周其他管道,不能形成上述的效應，這樣就會使牙齒移動的速度降低.force compression of PDlocclusion of blood vesselsformation of aneutysmsact as spring between tooth and alveolar bone, help in replenishing the squeeze film補充受擠壓血管的血流alternation in the chemical envioment decreased ox

16、ygen concentration in compressee areas血氧濃度降低blood gasses escape into local environmentfavorable environment for bone resorption3. BONE BENDING/PIEZOELECTRIC/BIOELECTRIC THEORY Piezoelectricity is a phenomenon observed in many crystalline material （骨壓電效應是從存在于骨內膠原成份晶狀樣物質中骨壓電效應是從存在于骨內膠原成份晶狀樣物質中觀察到觀察到的的

17、）. The deformation of the crystal structure produces a flow of electric current as electrons are displaced from one part of the crystal lattice to another.（當骨產生（當骨產生扭轉形扭轉形變變時，不對稱的晶體變形可以產生時，不對稱的晶體變形可以產生電荷電荷，當這種電荷在晶體層，當這種電荷在晶體層中運動時，會在其中產生電流效應）中運動時，會在其中產生電流效應） When the force is applied on a tooth, the

18、adjacent alveolar bone bends. the osteoclast (破骨細胞) cells start to active. 當牙齒受到正畸力量是,臨近的牙槽骨受壓或者受拉力而變形 Areas of concavity are associated with negative charge and cause bone deposition. Areas of convexity are associated with positive charge and cause bone resorption 張力側形成的凹面區(qū)域中帶負電荷，成骨細胞活動，而壓力側形成的凸面區(qū)域

19、中產生了正電荷，破骨細胞活動，牙槽骨外板也有類似的特點。4.the elasty of the bone 4.the elasty of the bone 骨彈性學說骨彈性學說 Kingsley WalkhoffKingsley Walkhoff： Without experiments ,he belives that the Without experiments ,he belives that the character of elasty character of elasty compressionan and compressionan and tenderness of bon

20、e lead to tooth movement.tenderness of bone lead to tooth movement. 在沒有實驗根據條件下認為：正畸牙移動是因在沒有實驗根據條件下認為：正畸牙移動是因為骨小梁有可壓縮性、彈性和柔性。為骨小梁有可壓縮性、彈性和柔性。5.the transformation of the bone 5.the transformation of the bone 骨轉化學說骨轉化學說 Oppenhein(1930)（狒狒和狗作實驗進行正牙實驗）狒狒和狗作實驗進行正牙實驗） when the right force is applied on the

21、 tooth ,both on the pression and tension sides,the alveolar bone s compact bone is dismished then the spongy bone and the trabcular bone appears After that there is osteoblast on the tension side,osteoclasts on the pression side . 牙齒在接受正常矯治力時，無論是壓力側還是張力側，牙槽嵴牙齒在接受正常矯治力時，無論是壓力側還是張力側，牙槽嵴致密骨板均消失，致密骨板均消失

22、， 以海綿骨代替，而后又出現(xiàn)橫行排列的骨小梁，以海綿骨代替，而后又出現(xiàn)橫行排列的骨小梁， 壓力側向牙端有破骨細胞，背牙端有成骨細胞，張力側向牙端壓力側向牙端有破骨細胞，背牙端有成骨細胞，張力側向牙端有成骨細胞，背牙端有破骨細胞出現(xiàn)。這二種作用使骨發(fā)生整有成骨細胞，背牙端有破骨細胞出現(xiàn)。這二種作用使骨發(fā)生整體改建，形成現(xiàn)代骨轉化學說。體改建，形成現(xiàn)代骨轉化學說。 6. 6.m me echanics and chemistry chanics and chemistry 機械機械化學學說化學學說JustusJustusLuft(1970)Luft(1970)：the mechanics chan

23、ge the the mechanics change the hyduoxyapatite s soluvility ,then osteoclasts hyduoxyapatite s soluvility ,then osteoclasts activate.activate.機械應力變化能改變羥基磷灰石晶狀體溶解度，引機械應力變化能改變羥基磷灰石晶狀體溶解度，引起破骨細胞作用。起破骨細胞作用。 Davidovitch ShanfeldDavidovitch Shanfeld：with the mechnics the with the mechnics the alveolar bon

24、e produce special bio-chemistry alveolar bone produce special bio-chemistry change,the cyclic adenosine monophosphate induce the change,the cyclic adenosine monophosphate induce the bone absorp and deposite.bone absorp and deposite.牙槽骨在機械應力作用下特有的牙槽骨在機械應力作用下特有的生物化學變化，環(huán)磷酸腺苷活性作用，促使骨形成和吸收。生物化學變化，環(huán)磷酸腺苷活性

25、作用，促使骨形成和吸收。 機械刺激機械刺激電位改變電位改變生物活性物質生物活性物質組織改建組織改建 These theories are neither incompatible nor mutually exclusive.既不互相排斥，也不是互相有矛盾的 From a contemporary perspective,i t appears that both mechanisms may play a part in the biologic control of tooth movement各種機制可能在牙齒移動的生物機制中都起到了一種作用。The biologic The biolo

26、gic basis 牙齒移動的牙齒移動的生物學基礎生物學基礎 the regenerativeness of the the regenerativeness of the alveolar bonealveolar bone： ( (頜骨可塑性頜骨可塑性) ) the dentoaleolar bone active the dentoaleolar bone active quikly with the resorption and quikly with the resorption and absorption absorption . .頜骨和牙槽骨生長發(fā)育最頜骨和牙槽骨生長發(fā)育最活

27、躍，它們改建主要是增生和吸收的質活躍，它們改建主要是增生和吸收的質和量相互平衡和量相互平衡。the resistance of the cementumthe resistance of the cementum ( (牙骨質的抗壓性牙骨質的抗壓性) )： with the orthodontic force ,due to with the orthodontic force ,due to the resistance of the cementum ,there the resistance of the cementum ,there is no resorption in the d

28、ento is no resorption in the dento cenmentumcenmentum. . 在正畸力作用下，牙骨質沒有多少吸收變在正畸力作用下，牙骨質沒有多少吸收變化，主要是其外表的類牙骨質具有抗壓性?；饕瞧渫獗淼念愌拦琴|具有抗壓性。the stability of the periontal ligament 牙周膜內環(huán)境穩(wěn)定：牙周膜內環(huán)境穩(wěn)定： with the force applied ,the PDl cells absorpe and compose constantly. 受外力作用，牙周膜細胞能根據功能和正畸需受外力作用，牙周膜細胞能根據功能和正畸需

29、要；具有不斷發(fā)生吸收要；具有不斷發(fā)生吸收 和合成功能。和合成功能。 the most important pinciple for teeth movement is complete PDL，if not ,like ankylosis, the teeth cant move . 牙齒移動的首要條件是完整的牙周膜，如果沒有牙周膜，牙根與牙槽骨直接接觸，發(fā)生骨性粘連，則不能移動。 for the implant,the way the bone connect with it just like ankylosis,there is no exisiting PDl,so the teeth

30、 cant move.that s why we take it as anchorage,but it still need light force 種植體修復中，骨融合是唯一的愈合方式，這種方式類似于骨粘連，應力緩沖的能力有限，沒有牙周膜，沒有動度，所以不能接受正畸移動，這也是其可以選為增強支抗的原因，但因其緩沖能力有限，仍然需要用輕柔的力量The reaction of the tissue組織反應組織反應1 1the absorption and resorption of the alveoar bonethe absorption and resorption of the alv

31、eoar bone 齒槽骨改建齒槽骨改建 with the proper force: the osteoblasts on the inner tension side and the outside of the pressure side active correspondingly ,then the bone deposite, the ostelclasts on the opposite sides appear,then the orignal bone start to absorp. 適當作用力大小情況下：適當作用力大小情況下： 張力側的內側面和壓力側外側面，均有成骨細胞活

32、動，新骨張力側的內側面和壓力側外側面，均有成骨細胞活動，新骨沉淀。沉淀。 張力側的外側面，壓力側內側面，破骨細胞活躍，原有骨質張力側的外側面，壓力側內側面，破骨細胞活躍，原有骨質被吸收。被吸收。 the osseous lamella of the dentoalvelar bone the osseous lamella of the dentoalvelar bone disapear,then the trabecula appear and arrange disapear,then the trabecula appear and arrange as the force direc

33、tion. as the force direction. 齒槽骨致密骨板消失，產生齒槽骨致密骨板消失，產生橫行排列的骨小梁，方向與受力方向一致。橫行排列的骨小梁，方向與受力方向一致。 on the one side ,the osteoblsats make the bone on the one side ,the osteoblsats make the bone to deposite ,on the other side ,the osteoclsats to deposite ,on the other side ,the osteoclsats make it absorb. i

34、t is called transition bone and make it absorb. it is called transition bone and the new bone form after half to one year.the new bone form after half to one year. 改建齒槽骨內新骨小梁橫向排列，稱之為改建齒槽骨內新骨小梁橫向排列，稱之為“過渡性骨過渡性骨”。新骨小梁一端破骨細胞活躍，骨質吸收；另一端牙齒成新骨小梁一端破骨細胞活躍，骨質吸收；另一端牙齒成骨細胞活動，骨質沉淀。牙齒停止移動后，過渡性骨需骨細胞活動，骨質沉淀。牙齒停止移動

35、后，過渡性骨需要要0.5-10.5-1年左右轉變成正常牙槽骨組織。年左右轉變成正常牙槽骨組織。 direct bone resportiondirect bone resportion( (直接骨吸收直接骨吸收) )：the the absorption happen on the surfaceabsorption happen on the surface如果壓力區(qū)牙槽如果壓力區(qū)牙槽骨面吸收是在骨表面直接發(fā)生，稱之為骨面吸收是在骨表面直接發(fā)生，稱之為直接骨吸收直接骨吸收； underming bone resportion (underming bone resportion (間接骨吸收

36、間接骨吸收) )：with with much more heavy force ,the absorption happen much more heavy force ,the absorption happen further than the surface further than the surface 作用力過大時，骨吸收作用力過大時，骨吸收有時不在牙槽骨內面直接吸收，而在稍遠處發(fā)生骨吸有時不在牙槽骨內面直接吸收，而在稍遠處發(fā)生骨吸收，這種吸收為收，這種吸收為間接骨吸收間接骨吸收或或“潛行性骨吸收潛行性骨吸收”（或（或“挖掘性骨吸收挖掘性骨吸收”）。 “ “潛行性骨吸收潛行性骨吸

37、收”使牙齒移使牙齒移動變緩，被矯治牙產生松動、疼痛。動變緩，被矯治牙產生松動、疼痛。2.the resportion and deposition of the PDL 牙周膜反應牙周膜反應 with the orthodontic force ,one with the orthodontic force ,one sides PDL under pressure ,but on the sides PDL under pressure ,but on the other side ,under tension ,then it other side ,under tension ,then

38、 it start to metabolize.start to metabolize.牙齒受到矯治力的牙齒受到矯治力的作用后，一部分牙周膜受牽引，另一部分作用后，一部分牙周膜受牽引，另一部分牙周膜受壓迫。牙周膜將產生代謝變化牙周膜受壓迫。牙周膜將產生代謝變化 tension zone 張力側：張力側：not only are existing fibers in the pdf entrpped passively by adwancing front to form Shappeys fibers,but new are also secreted simultaneously by fi

39、broblasts migrating from the bone 牙周纖維牽拉伸長，間隙增寬，牙周纖維牽拉伸長，間隙增寬，膠原纖維和基質膠原纖維和基質增增生，生，成纖維細胞成纖維細胞增殖，增殖，成骨細成骨細胞胞分化活躍。當外力降低或分化活躍。當外力降低或消失，牙周纖維再排列和附著，繼而恢復正常牙周膜寬度。消失，牙周纖維再排列和附著，繼而恢復正常牙周膜寬度。 pressure side壓力側：壓力側：the fibers become more narrow and the blood blows more slowl then collagen fiber and substrate van

40、ish,the change above induce osteoclasts牙周膜受壓迫而寬度變窄，血牙周膜受壓迫而寬度變窄，血管受壓，血流減緩，細胞分化，膠原纖維和基質降解，破管受壓，血流減緩，細胞分化，膠原纖維和基質降解，破骨細胞活躍。骨細胞活躍。3.牙骨質組織反應牙骨質組織反應 It is reasonably that when the tooth It is reasonably that when the tooth move ,the cementum inevitably absorb.but move ,the cementum inevitably absorb.but

41、depending on the resistance of the depending on the resistance of the cenmentum, the absorption ocurres only cenmentum, the absorption ocurres only in the small zone ligtly ,then the in the small zone ligtly ,then the secondary cenmentum repair it quikly. secondary cenmentum repair it quikly. 臨床上希望使

42、齒槽骨吸收，牙齒移動迅速，不造成牙骨質吸收。臨床上希望使齒槽骨吸收，牙齒移動迅速，不造成牙骨質吸收。實際上牙骨質不可避免實際上牙骨質不可避免輕度吸收輕度吸收。由于類牙骨質抗壓性質，決。由于類牙骨質抗壓性質，決定吸收程度較輕，范圍小。成牙骨質細胞形成牙骨質，吸收后定吸收程度較輕，范圍小。成牙骨質細胞形成牙骨質，吸收后的陷窩很快由的陷窩很快由新生牙骨質進行修復。新生牙骨質進行修復。the primary and secondary cementum 4.牙髓組織反應牙髓組織反應the reaction of the pulpwith the proper force ,the apex is un

43、der light pressure,the pulp with the proper force ,the apex is under light pressure,the pulp is on congestion and the activity may become lower.After the is on congestion and the activity may become lower.After the movement ,the pulp is normal movement ,the pulp is normal with more heavy force ,the

44、pulp may cecrosis with darker with more heavy force ,the pulp may cecrosis with darker colour,but after the RCT ,the tooth can move as usual.colour,but after the RCT ,the tooth can move as usual.1.1.當矯治力值在理想范圍之內，根尖部輕度受壓，牙髓組織輕度充血，牙當矯治力值在理想范圍之內，根尖部輕度受壓，牙髓組織輕度充血，牙髓活性可能稍微下降，牙齒停止移動后又恢復正常。髓活性可能稍微下降，牙齒停止移動

45、后又恢復正常。 2 2當矯治力力值過大，則會導致牙髓炎性反應。如果根尖血管阻塞，則可當矯治力力值過大，則會導致牙髓炎性反應。如果根尖血管阻塞，則可能發(fā)生牙髓炎，牙髓變性，甚至壞死，牙冠顏色發(fā)生（暗紅色）改變。能發(fā)生牙髓炎，牙髓變性，甚至壞死，牙冠顏色發(fā)生（暗紅色）改變。3 3死髓牙如果進行治療后，根尖周組織正常，也可以進行正畸移動（根管死髓牙如果進行治療后，根尖周組織正常，也可以進行正畸移動（根管治療后）治療后） for the teeth after RCT,the demand list as follows: no clinic symptoms ,normal X-rays,at le

46、ast 6 ms obseration for teeth after trauma,light force ,x-rays every 6 m 對于根管治療后的牙齒移動有以下要求：無臨床癥狀、X線檢查滿意、外傷 或根尖治療后至少觀察6個月，無異常時可正畸移動，但是應使用輕柔的力量，每6個月X線檢查5.the effect on the root and apex 正畸對牙根及根尖組織影響正畸對牙根及根尖組織影響 For the root and apex ,the reaction happen on the For the root and apex ,the reaction happe

47、n on the surface,just as the absorption of cementum.surface,just as the absorption of cementum. 牙根對正畸力的組織反應主要是牙根表面吸收和根尖吸收。牙根對正畸力的組織反應主要是牙根表面吸收和根尖吸收。牙根表面吸收的組織反應同上述牙骨質吸收相同。牙根表面吸收的組織反應同上述牙骨質吸收相同。 The aborption happen on the root is connected with the force applied. Most of the teeth s root would absorb

48、 ,but it is difficult to see on the X-rays 牙根輕微吸收時，吸收發(fā)生在根尖，與矯治力大牙根輕微吸收時，吸收發(fā)生在根尖，與矯治力大小相關。小相關。 大部分牙移動時均會發(fā)生，一般在牙骨質表面，大部分牙移動時均會發(fā)生，一般在牙骨質表面，呈淺在性，牙科呈淺在性，牙科X X片上較難發(fā)現(xiàn)。片上較難發(fā)現(xiàn)。 0 0級：級：complete root complete root 牙根不存牙根不存在可以識別的吸收，根尖完整。在可以識別的吸收，根尖完整。 1 1級：級：only the apex surfaceonly the apex surface牙根尖表面不均勻規(guī)則，

49、開始顯示牙根尖表面不均勻規(guī)則，開始顯示處吸收征候，僅僅限于根尖表面。處吸收征候，僅僅限于根尖表面。 2 2級：級：blunt on the rootblunt on the root牙根牙根呈鈍狀輕度吸收。呈鈍狀輕度吸收。級：級：obvios blunt obvios blunt 牙根鈍狀牙根鈍狀吸收明顯，約占牙根長度吸收明顯，約占牙根長度1/3-1/51/3-1/5。級：級：serious absportionserious absportion牙根牙根嚴重吸收，吸收約占牙根長度嚴重吸收，吸收約占牙根長度1/31/3以上。以上。the absorption of the apex 根尖吸收的

50、兩種情況根尖吸收的兩種情況 1 1the going-on absorption the going-on absorption 進行性吸收進行性吸收, ,most most happen in the apex,it can be seen from x-happen in the apex,it can be seen from x-raysrays大部分發(fā)生在根尖，呈進行性。可在大部分發(fā)生在根尖，呈進行性?？稍赬 X片上觀片上觀察到。察到。 2 2specific absorptionspecific absorption 特發(fā)性吸收特發(fā)性吸收：depending on the pers

51、onality,but the force depending on the personality,but the force can accelerate it ,the ratio between femal can accelerate it ,the ratio between femal and mal is 3.7:1 and mal is 3.7:1 與個體敏感性相關，與矯治力與個體敏感性相關，與矯治力無關無關. . 在所有牙齒上可以不同程度的發(fā)生，但矯治力會在所有牙齒上可以不同程度的發(fā)生，但矯治力會加重其吸收速度與程度。女性與男性牙根吸收比加重其吸收速度與程度。女性與男性牙根

52、吸收比率約為率約為3.7:13.7:1，但與男女激素水平無關。，但與男女激素水平無關。 the absorption of the apex is inevitable the absorption of the apex is inevitable all kinds of movement can lead to all kinds of movement can lead to resorption,especially for incisorss intrusionresorption,especially for incisorss intrusion so the proper f

53、orce should be continous and so the proper force should be continous and light ,trying to decrease the absorptionlight ,trying to decrease the absorption 牙根吸收（變短、鈍）是正畸治療的牙根吸收（變短、鈍）是正畸治療的必然后果必然后果，它它的發(fā)生不可預測；的發(fā)生不可預測； 任何類型的牙齒移動都可以引起牙根吸收，而任何類型的牙齒移動都可以引起牙根吸收，而切牙壓切牙壓低低時牙根吸收最嚴重。時牙根吸收最嚴重。 正畸治療應該使用正畸治療應該使用間歇力

54、、輕力間歇力、輕力，盡可能減少牙根吸盡可能減少牙根吸收的程度。收的程度。 切牙過度傾斜移動，冠根反向移動，根尖突破骨皮質6. effect in the TMD正畸對顳下頜關節(jié)及下頜骨影響正畸對顳下頜關節(jié)及下頜骨影響 when the condyle process move forwards ,the posterior of the glenoid fossa hyperplasia,the anterior absorb,the posterior ascending ramus hyperplasia while the anterior absorb when the condyle

55、 process move backwards ,do as the opposite 適度矯治力作用下適度矯治力作用下 如果使下頜髁突前移，關節(jié)凹后壁增生，前壁吸收，如果使下頜髁突前移，關節(jié)凹后壁增生，前壁吸收，下頜升支后緣增生，升支前緣及內角吸收。下頜升支后緣增生，升支前緣及內角吸收。 如果使下頜髁突后移，反應與上述相反如果使下頜髁突后移，反應與上述相反7.腭中縫的變化 the centre joint of palate 青春期前腭中縫無完全的骨縫聯(lián)合，其間由結締組織相連。組織切片中，腭中縫是一條不規(guī)則的分界線，由左右骨縫交錯向對方而形成。其間是一條潛在的裂隙，被結締組織充填。 Befo

56、re adolescence ,the centre joint ist filled up with complete bone ,but syndesm in the latent space between the two interlck palate. 快速腭開展中，隨著擴弓進行，期間的 潛在裂縫逐漸擴大，骨質增生發(fā)生在每側骨質頂端，成骨細胞在此聚集，形成類骨質，同時，血管數目增多，纖維細胞數目增多，活躍的組織增生狀態(tài)。隨著類骨質的鈣化，腭中縫逐漸形成骨性連接。 With the RPE, the latent space expand ,the bone deposite in b

57、oth sides ,the number of the osteoblasts 、fiber cells and blood vessels increase while,after the bone calcification ,the bone joint get formed.8.面部肌肉的變化 The facial muscles 正畸矯治過程中，由于硬組織形狀和位置的改變，口頜及面頰部肌肉等軟組織也相應發(fā)生改變，以取得新的平衡。如改變下頜的位置，肌電檢查到下頜向前時翼外肌電活動增強。這是功能性矯治器治療的基礎。 When the bone position change ,the

58、muscles follow with it to make new balance.This is the basis for functional treatment. 用神經肌肉機制矯治早期畸形，在兒童時期易建立反射通路，機體很快適應。另外，牙齒頜骨到達新的 位置后，肌肉的動力平衡后，才會得到穩(wěn)定的治療效果。如上頜前突、開合等矯治結束后還要肌肉訓練。 The adolescence can adapt to the functional bone and musle position change quikly,only with the new musle balance ,can t

59、he position be firm enough .For the case,after the treatment of the openbite and m.x protursion ,muscle training is necessary.9.the effect of milk teeth movement on the 9.the effect of milk teeth movement on the permanent teethpermanent teeth 乳牙移動對恒牙胚的影響乳牙移動對恒牙胚的影響the permanent teeth reside in the l

60、ingual side of the milk,the premolar on the root branching when the milk teeth root,the permanent move together with the milk ,but too much heavy force make it move tipply,the permanent move to the opposite way 恒切牙位于乳牙舌側，前磨牙位于根分叉處恒切牙位于乳牙舌側，前磨牙位于根分叉處乳牙根未吸收情況下，恒牙隨乳牙一起移動。乳牙根未吸收情況下，恒牙隨乳牙一起移動。 正畸力過大、乳牙呈傾